Effect of Continuous Inhalation of Ethanol Vapors in the Rat

Rats were exposed to continuous inhalation of ethanol vapors in an inhalation chamber plus daily injections of an alcohol dehydrogenase inhibitor pyrazole (68 mg/kg, i.p.). Ethanol vapors entered the inhalation chamber at flow rates of from o.45 liters/min. to 0.95 liters/min. which when mixed with a constant stream of air (5.0 liters/min) produced chamber concentrations of from approximately 8.8 mg/ liter to 26.5 mg/liter. Rats exposed to these conditions for 5 to 7 days developed blood ethanol levels of 0.8J± 0.09 mg/ml/blood to 2.19 ± 0.14 mg/ml/blood. Administration of pyrazole with or without ethanol caused weight loss in these rats. Rats developed tolerance to ethanol after continuous inhalation of ethanol vapors for 5 days demonstrated by increased onset and decreased duration of ethanol-induced narcosis. After 5 days of continuous ethanol inhalation rats became physically dependent on ethanol and developed withdra wal signs of piloerection, abnormal posture, tremors, convulsions, headshakes, tail-lifts and mortality upon cessation of ethanol administration. The four withdrawa l signs of piloerection, abnormal posture, tremors and convulsions were combined into an ethanol withdrawal syndrome measurement. Pretreatment of ethanol dependent rats JO minutes prior to J6 hours of ethanol withdrawal, the period of maximum int e nsity of the withdrawal syndrome,

0.09 mg/ml/blood to 2.19 ± 0.14 mg/ml/blood. Administration of pyrazole with or without ethanol caused weight loss in these rats.
Rats developed tolerance to ethanol after significantly reduced apomorphine-induced aggression in ethanol withdrawn rats. During withdrawal from ethanol, mortality was 20% among rats exposed for 5 days to ethanol inhalation and not treated with any drugs during' withdrawal .
None of the drugs used in this study significantly reduced the mortality rate in ethanol withdrawn rats . However, administration of chlordiazepoxide (160 mg/kg, i.p.) prior to the thirty-sixth hour of ethanol withdrawal resulted in a signifi cant increase in the mortality to 75%. This same dose of chlordiazepoxide administered intraperitoneally to untreated rats resulted in a mortality of 66.7% of the rats treated within 36 hours after injection.  The methods used were schedule-induced polydipsia (Falk, 1972), liquid diets containing ethanol (Freund, 1969;Branchey et al., 1971;Pieper et al., 1972;Pieper and Skeen, 1972), gastric or nasogastric intubations (Majchrowicz, 1973;Ellis and Pick, 1970b.; Essig and Lam, 1968), intravenous administration (Deneau et al., 1969;Winger et al., 1970) and inhalation with or without pyrazole (Gold--.- stein and Pal, 1971;Littleton et al., 1974;Roach!:.! al., 1973). The inhalation technique has proved to be most applicable for experimental studies and has been used for testing the effects of drugs on the ethanol withdrawal reaction (Goldstein, 1972b.;. The evidence indicates that maintainance of consistently high blood ethanol levels for several consecutive days is necessary for production of ethanol physical dependence (Mello and Mendelson,197la;197lb.). Majchrowicz (1973) and Roach et al. (1973), out-· lined the withdrawal signs in rats. Although, comprehen-1 ,, ' _______ ,_._..,. ------· sive behavioral rating scales have been developed for mice 2 (Irwin, 1968;Goldstein, 1972a.;Freund, 1969) few have been developed for other species and none for the rat (Mello, 1973).
Behavioral tolerance to alcohol in alcoholics has been demonstrated (Isbell et al., 1955;Newman, 1941). However, the biochemical mechanisms underlying tolerance to ethanol are unknown. Metabolic tolerance to alcohol in animals (Hawkins et al., 1966) and man (Mendelson et al., 1966) has been shown, however metabolic changes cannot adequately explain the tolerance seen in animals or man (Mendelson, 1971;Mello 1972;LaBlanc et al., 1969) and a role for cellular adaption in the central nervous system is necessary.
The mechanisms underlying the expression of withdrawal signs upon cessation of ethanol administration are unknown.
Roles for hypomagnesemia and respiratory alkalosis (Victor, 1973), sleep disturbances (Gross et al., 1974), and denervat i on supersensitivity (Jaffe and Sharpless, 1968) have been proposed as relating to the expression of withdrawal signs.
Theories about the underlying mechanism involved have ineluded enzyme repression and derepression (Goldstein and Goldstein, 1967), increased receptor sites (Collier, 1965), fo r mation of morphine-like alkaloids within the central nervous system , formation of false adrenergic transmitters (Cohen, 1973a.;1973b.) and inhibition of nerve impulses (Wallgren, 1973;Tabakoff et al. , 1973). J Treatment of the acute alcohol withdrawal syndrome has been reviewed by Gross et al. (1974). Goldstein (1972b.), compared several drugs in the treatment of ethanol withdrawal signs including ethanol, chlordiazepoxide, promazine and barbiturates.
It has been shown that ethanol does act as expected in reducing the withdrawal severity of alcohol dependent and withdrawn animals (Goldstein, 1972b.; Ellis and Pick, 1972b.), although such treatment in man is not advised (Isbell et al., 1955;Golbert ~al., 1967). Chlordiazepoxide is considered one of the most effective treatments for delirium t~emens (Gross et~., 1974;Favazza and Martiri, 1974) and is effective in animals as well (Goldstein, 1972b.).
The use of haloperidol in the treatment of acute alcohol withdrawal has been studied, although not extensively (Gross~ al., 1974), however morphine has not been reported in the treatment of acute alcohol withdrawal. Gross et al. (1974), presented evidence that haloperidol is at least as effective as paraldehyde or chlordiazepoxide in reducing withdrawal severity during the first 48 hours of alcohol withdrawal in man. It has been proposed that ethanol, via its metabolite acetaldehyde, may cause formation of morphine-like alkaloids in the central nervous system  and that acute morphine administration blocks dopamine receptors similar to haloperidol, but, is less potent (Puri~ al.,197J). Therefore, the use of ethanol, Rats made physically dependent on morphine show spontaneous aggression during withdrawal without any other stimulation . This spontaneous aggression is enhanced by administration of apomorphine or amphetamine and is blocked by the narcotic methadone and the dopamine receptor blocking neuroleptic haloperidol . It has also been shown that chronic haloperidol administration increases the sensitivity of rats to induction of aggressiori by small doses of apomorphine (Gianutsos et al., 1974a.). Apomorphine is a known stimulator of dopamine receptors (Anden t l al., 1967;Ernst, 1.967) . It has also been shown that morphine dependent rats withdrawn for protracted periods of up to JO days show evidence of latent dopaminergic supersensitivity as represented by aggressive behavior upon aggregation (Gianutsos et al., 1974b.).
This investigation was undertaken to develop an animal model of ethanol physical dependence in the rat using a modification of the inhalation procedure described by Goldstein and Pal (1971). Also, undertaken were investi- 4. · That drugs known to have cross-tolerance with ethanol will be effective in reducing the severity of the ethanol withdrawal reaction (ex. chlordiazepoxide).
5. That administration of m'orphine will reduce the intensity of t he ethanol withdrawal syndrome.
6. That some sign of morphine withdrawal will be seen in ethanol dependent and withdrawn rats.  Alcoholism has been shown to be a form of addiction, as defined in terms of the traditional pharmacological criteria of tolerance and physical dependence (Isbell~ al., 1955;Mendelson, 1964;Victor and Adams, 1953). Recognition that alcoholism is an addictive disorder has proceeded slowly and at one time it was thought that the alcohol withdrawal syndrome reflected intercurrent illness, vitamin or nutritional deficiencies (Victor and Adams, 1953). Now it has been shown that alcohol withdrawal signs and symptoms occur in healthy, well nourished alcoholics (Mendelson, 1964) and in experimental animals (Goldstein and Pal, 1971), solely as a fun~tion of withdrawal of alcohol. less severe in alcoholics than in abstainers (Jetter, 1938).
The development of tolerance in alcoholics has been demonstrated by a number of investigators (Isbell et al., 1955;Newman, 1941). However, the biochemical mechanisms subserving increased tolerance are unknown, but two general mechanism have been postulated: an enhanced rate of metabolism and/or an increased degree of cellular adaption to ethanol in the central nervous system.

Metabolic Tolerance
Both experimental animals (Hawkins t l al., 1966) and man (Mendelson t l tl•' 1966) may develop increased rates of ethanol metabolism following chronic ethanol administration.
The increased ethanol metabolism in experimental animals has been correlated with an increase in hepatic alcohol de-·hydrogenase activity (Hawkins et al., 1966;Mendelson et al., 1965). However, differences in metabolic rate alone do not adequately explain the high quality of tolerance seen in animals and man (Mendelson, 1971;Mello, 1972).

Cellular Tolerance
Since there is no good evidence that metabolic processes can adequately account for the degree of tolerance observed in alcoholics, cellular adaption to ~thanol appears to be a more likely explanation for the phenomena of  Mendelson (1971), has reviewed the evidence relating to the possible role of ethanol as related to each possible mechanism, coneluding that little evidence exists supporting any of the proposed mechanisms of cellular tolerance discussed by Axelrod (1968). Furthermore,. there is little conclusive evidence supporting the many hypotheses (see Mechanisms of Tolerance and Physical Dependence) advanced to explain tolerance (Mendelson, 1971). A general consensus of many neurophysiologists and neurochemists is that ethanol acts on membrane structure and function, which reflects the lack of decisive evidence available (Mendelson, 1971 (Isbell et al.,19 55; Mello and Mendelson, _ 1970) and animals (Goldstein, 1972a.) while blood ethanol levels are still high. Goldstein (1972a.), found that withdrawal signs after a single large dose of alcohol began when blood ethanol levels were as high as 3 mg/ml and convulsions were seen in some mice with blood ethanol levels greater than 1 mg/ml.

Hypomagnesemia and Respiratory Alkalosis
There has been a growing body of data on the relationship between signs associated with alcohol withdrawal on the one hand and hypomagnesemia and respiratory alkalosis on the other. This area has recantly been reviewed by Victor (1973), who has been intricately involved in research in this area. Vi ctor (1973), noted that three separate studies, of which two were clinical and one experimental, involving a total of 58 patients, the only two consistent chemical abnormalities during withdrawal were hypomagnesemia and respiratory alkalosis. Furthermore, he observed that the severity of these chemical abnormalities were related and followed a similar time course as the seizures associated with the wi t hdrawal.
As to the mechanism involved Victor (1973), suggested that it may involve rebound suppression of the resp i ratory centers during alcohol intoxication with respiratory alkalosis and magnesium shift in response ---~ --·----11 to the alkalosis. He also suggested that a concomitant mechanism might be cerebral hypoxia secondary to the respira:'t'ory alkalosis.  (Gross et al., 1966;Gross and Goodenough, 1968;Green~ berg and Pearlman, 1967;Johnson~ al., 1970). Levels as high as 100% Stage I REM (normally 20%) were observed in hallucinating patients in full-blown delirium tremens (Gross et al ., 1966;Johnson~ al., 1970). Thus, in alcoholics there appears to be a relationship between REM and the hallucinations of withdrawal . Alcohol also reduces REM in normals (Yules~ al., 1966) and in chronic alcoholics (G~oss and Goodenough, 1968). This suggests that an important mechanism involved in the hallucinogenesis during acute alcohol withdrawal may be rebound of REM and its associated dream activity. If REM rebound were great enough it might break through into the waking state as hallucinations (Fisher and Dement, 1963) as was once observed (Gross et al., 1966). There is also a marked reduction in delta 12 sleep which may be an important condition permitting very high levels of REM (Johnson et al., 1970). Johnson et al. (1970), suggested that the sleep changes may result from the effect of ethanol on brain biogenic amines. This position is shared by Williams and Salamy (1972), Lester et al., (1973) and Kissin ~al. (1973).
Denervation Supersensitivity Jaffe and Sharpless (1968), pointed out that many withdrawal phenomena involve an exaggeration of behavior that is ordinarily suppressed by the agent which induces dependence.
For example, morphine ingestion in man is associated with myosis while mydriasis is observed during morphine withdrawal .
In addition to the concept of rebound hyperexcitability exists during the time the agent is ingested (Jaffe and Sharpless, 1968 ate withdrawal in the addicted cat is associated with a decreased threshold for PTZ-induced seizures (Jaffe and Sharpless, 1965). Jaffe and Sharpless (1965), concluded that the lowered threshold for seizures was consistent with a "disuse supersensitivity" model of physical dependence and that the time course for the development of physical dependence is similar to that of denervation supersensitivity in the PNS as observed by Fleming and Trendelenburg (1961).

MECHANISMS OF TOLERANCE AND PHYSICAL DEPENDENCE
Tolerance and physical dependence have been discussed as ~eparate entities although both are essential criteria for addiction. Tolerance and physical dependence may represent phenomena subserved by a common mechanism or may represent different biochemical and physiological processes. It is well known that certain centra~ly acting drugs produce tolerance but no physical dependence. For example, amphetamine produces no clear-cut dependence, while t olerance to increasing doses is common (Jaffe, 1970). Way et al. (1969), has presented strong evidence that a .:..---·---14 Enzyme Expansion Theory Goldstein and Goldstein (1967), have developed an enzyme expansion theory of' drug tolerance and physical dependence. This theory consists of' tolerance and physical dependence as a unitary mechanism based upon represssion and derepression of' enzyme synthesis. Substance C in Figure 1 is considered excitatory at some regional or cellular level · in the central nervous system. Substance C is synthesized   .
Al though some authors believe that ethanol's effect on 16 nerve membranes is primarily involved in the production of physical dependence upon ethanol either directly (Wallgren, 1973) or indirectly via binding of biogenic amine aldehydes (Tabakoff £.i al., 1973), synaptic events involving catecholamines are not dismissed.
Chronic ethanol administration is known to cause sustained release of norepinephrine in the brain (Hunt and Majchrowicz, 1974), which has lead to investigation and speculation that this release of norepinephrine is directly responsible for at least some of the characteristics of ethanol tolerance and physical dependence (Reis, 1973;French et al., 1974). Davis et al. (1967b.), found that ethanol and acetaldehyde cause release of norepinephrine and alter its metabolism from the normal oxidative pathway towards a reductive one of a glycol excretion product (methoxyhydroxyphenylglycol, MHPG) a similar shift involving serotonin was also seen (Davis et al., 1967a.). However, although the metabolism of dopamine via the oxidative route was reduced no increase in the reductive pathway was seen (Davis, 1971). The shift in catecholamine metabolism is believed to be due to the inhibition of aldehyde reductase in the brain by acetaldehyde formed from the metab-

17
from Kersten et al. (1975), who found that the blood levels of acetaldehyde were elevated in alcoholics compared to normals after equal doses of ethanol and at similar blood ethanol levels. Hasumura et al. (1975), presented evidence that the elevation in acetaldehyde levels in alcoholics may result from the chronic intake of ethanol, since it was found that in rats chronic administration of ethanol1.nhibited acetaldehyde oxidation by liver mitochondria.  (Battersby, 1961;Spenser, 1966). , proposed that the formation of such alkaloids may represent the mechanism for the addiction liability of ethanol (see Figure 2 for proposed mechanism  (Walsh, 1973). This hypothesis has been criticized by Seevers (1970) and by Goldstein and Judson (1971), based up-.
on the failure of naloxone to induce a typical narcotic withdrawal sign (jumping) in ethanol dependent mice.
There has also been presented in the literature, almost simultaneously to the above studies, studies which have shown that acetaldehyde or formaldehyde will condense, via the simple Pictet-Spengler reaction, with dopamine or norepinephrine to form tetrahydroisoquinoline alkaloids (THis) (Cohen, 1971;Yamanaka et al., 1970). Figure   Cohen and his co-workers after much experimentation proposed that these condensation products act as false adrenergic transmitters and meet the essential requirements of synthesis, uptake, storage and release by the adrenal and peripheral adrenergic nerves (Cohen,197Ja.;197Jb.).
These hypotheses concerning acetaldehyde are very provocative and have created much furor in the past few years.
Similarities between the actions of morphine and ethanol are not unknown in the literature. Ross et al. (1974), has shown that both morphine and ethanol as well as salsolinol (a THI) and reserpine deplete regional brain Ca++, however, only the effects of morphine, ethanol and salsolinol were antagonized by naloxone a narcotic antagonist. Swartz et al. (1974), showed that acute doses of ethanol inhibit the uptake and binding of Ca++ by cardiac microsomes. Therefore, if one examines the available data: 1. ethanol and salsolinol deplete regional brain calcium, possibly via inhibition of uptake and binding 2. the depletion of calcium would favor release of catecholamines (NE) over THis J. the release of NE after ethanol administration is already well known as is the diversion of its metabolism in the presence of ethanol or acetaldehyde. Furthermore, it has been shown that barbiturates also induce a similar shift in norepinephrine metabolism as does ethanol or acetaldehyde (Davis ~al., 1974) presumed to be due to inhibition of aldehyde reductase as shown by Tabakoff and Erwin (1970).  (Allan and Swinyard, 1949) and motor performance (Gibbins~ al., 1968;Moskowitz and Wapner, 1964;LaBlanc et al., 1969). In most instances changes in metabolic distribution cannot explain ;the degree of tolerance observed (LaBlanc et al., 1969;Mendelson, 1971).
Increases in the rate of ethanol elimination have been shown in man (Mendelson et al., 1966) and animals (Gibbin~ et al., 1966). Animals made physically dependent on ethanol have also been shown to have increased rates of ethanol elimination (Mello, 1973). However, the behavioral methods cited above have been carried out in non-dependent animals, possibly due to the interference of the withdrawal reaction with the performance of such tasks as rotor rod per-  (Lester, 1966;Mello, 1968;Myers and Veale, 1972;).
Recently, several groups have produced physical dependence upon alcohol in animals using oral, intragastric, intravenous and inhalation routes of' administration. Although, there is some interspecies variability in the types of' withdrawal signs, there has been reasonable agreement f'rom diff'erent laboratories (Mello, 1973). Majchrowicz (1973) and Roach 2.E_ al . (1973), have outlined most of' the ethanol withdrawal signs in rats. Withdrawal after several days of' 3-5 f'ractional daily doses of' ethanol 12-15 g/kg/day in rats resulted in withdrawal signs of' "squealing, hyper-activity, ventromedialdistal forepaw flexion , spascity, tremors, teeth chattering, wet shakes, induced and spontaneous convulsions" (Majchrowicz, 1973). Withdrawal after 7 days of inhalation of ethanol without pyrazole resulted in tremors , forward tail-arching, hypersensitivity to sound and touch, abnormal postures and convulsions (Roach et al., 1973). However, neither investigators attempted to do more than group the withdrawn rats based upon an overall subjective interpretation of withdrawal severity, rather than by systematically assessing each sign.
Although, comprehensive behavioral rating scales have been developed for withdrawal signs in mice (Irwin, 1968;Goldstein, 1972a.;Freund, 1969) few have been developed for other species and none for the rat (Mello, 1973). Since , the grossly observable withdrawal signs presumably represent central nervous system hyperexcitability directly by examining the seizure threshold to electro-convulsive shock (McQuarrie and Fingl, 1958)' audiogenic stimuli and convulsive drugs (Ratcliffe, 1972) and the startle response . Falk (1972), reported successful application of a behaviora l technique, schedule-induced polydipsia, in producing ethanol physical dependence in the rat. The polydipsia phenomena was first reported by Falk (1961). Substitution of a 5 or 6% ethanol solution for water resulted in daily intak. es of between 11 and 15 g/kg with blood levels v Freund (1969), feed liquid diets containing 35% of the caloric intake as ethanol to mice on a food-restricted diet.

Oral and Intragastric Administration
Although, this procedure induced gross intoxication and physical ' dependence in four 'days, the severe weight reduction, to 65% of their free-feeding weight, prior to ethanol administration introduces some serious inadequacies into this model (Ogata et al., 1972). It has been shown both in animals and man that the rate of ethanol metabolism is reduced by as much as 50% in fasted organisms (Forsander et al., 1965;Mendelson, 1970;Owens and Marshall, 1950;Smith and Newman, 1959). The Freund method has also been applied to rats (Branchey et al., 1971).
Several unsucces sful studies using the polydipsia technique with rhesus monkeys to induce physical dependence did yield the important result that maintenance of consistently hi g h blood ethanol levels on successive days is important for induction of physical dependence on ethanol (Mello and Mendelson,197la.;197lb.).
Us e of on e to seven-month-old chimpanzees (Pan troglodytes) given liquid diets with 45% of the calories as eth- dependence (Pieper et~., 1972). The chimpanzees maintained normal weight gain, consumed ethanol at 2-8 g/kg/day with blood levels ranging between 0.5-J.O mg/ml for 6-10 weeks ana displayed hyperreflexia, irritability, spastic rigidity and tonic-clonic convulsion upon abrupt withdrawal of ethanol (Pieper~ al., 1972). This liquid diet .procedure was extended to adult rhesus monkeys with comparable results including significant increases in the rate of ethanol metabolism (Pieper and Skeen, 1972).
Forced alcohol administration procedures have proved to be consistently effective in producing alcohol dependence in monkeys (Ellis and Pick, 1969;1970b.;1971) and in dogs (Ellis and Pick, 1970a.;E~sig and Lam, 1968;1971). Ellis and Pick (1969), were the first to report that naso-

26
which a monkey could lever press to self'-administer ethanol.
There are striking similarities between the patterns of intravenous self'-administration of' ethanol by the rhesus monkey and spontaneous drinking patterns in human alcoholics (Deneau et al., 1969;Mello and Mendelson, 1972;Nathan~ al., 1970;Nathan et al., 1971;. Human alcoholics, given an operant task, f'requently alternate drinking episode of' J-6 days with relatively abstinent work periods associated with partial withdrawal signs lasting 2-J days (Mello a n d Nathan et al. , 1970;Nathan~ al., 1971). Alcohol self'-administration in monkeys is also punctuated by periods or spontaneous abstine n ce and partial withdrawal signs (Deneau et · al., 1969;). This raises some basic questions concerning the ambiguous relationship between physical dependence and subsequent drug self-administration. It is usually assumed that once an addictive drug-taking pattern is estab- tail-lifts, startle reactions and spontaneous seizures were seen with peak intensity occurring 10-12 hours after withdrawal (Goldstein and Pal, 1971;Goldstein, 1972b.). This model has the advantage of producing large numbers or physically dependent animals in a relatively short time.
Goldstein has used this model to study the mlationship between alcohol dose and the intensity of withdrawal signs, effects of drugs which modify neurotransmission and the effect of other drug on the withdrawal reaction (ex. chlordiazepoxide) (Goldstein, 1972a.;1972b.;. Roach et al. (1973), has reported production of physical dependence in rats by inhalation of ethanol without the use of pyra- Alcohol and Pyrazole Goldstein (1972a.), found that the use of pyrazole was necessary, since without it blood ethanol levels fluctuated drastically resulting in a high mortality rate during ethanol inhalation.
Pyrazole inhibits the metabolism of ethanol both in vitro and in vivo. Theorell et al. (1969) , reported that pyrazole inhibited alcohol dehydrogenase by formation of a ternary complex with ADH and nicotinamide adenine dinucleotide (NAD). Lester£! al. (1968) and Goldberg and Rydberg (1969), showed that pyrazole inhibited ethanol metabolism in rats and that the minimal lethal dose was approximately 18 mmole/kg (1200 mg/kg). Lester and Benson (1970), found that the metabolism of other alcohols including ethanol are inhibited by pyrazole as well as some oximes and amides. Rydberg et al. (1972), has studied the kinetics of pyrazole and reported that not only does pyrazole inhibit ethanol metabolism, but that administration of ethanol increased the half-life of pyrazole from 13 to 21 hours. , suggested that ethanol might inhibit a microsomal m~chanism for pyrazoles elimination (Rubin et al., 1971). Bustos£! al. (1970) and Morgan and DiLuzio (1970) have dealt with the induction of fatty-livers in animals treated with pyrazole and ethanol.
Pyrazole is known to have hepatotoxic effects (Lelbach, 1969;Lieber et al., 1970) and some synergistic action with

29
ethanol upon the central nervous system (Goldberg et al., 1972). However, overall pyrazole is well tolerated in rats at doses which are highly effective at reducing ethanol metabolism (Lester and Benson, 1970) and in most cases toxic effects are not seen unti~ the dose of pyrazole is quite high, usually greater than several hundred milligrams per kilogram of body weight.

TREATMENT OF ETHANOL WITHDRAWAL
There is a vast literature on the use of a wide variety of drugs in the specific rather than the supportive treatment of the alcohol withdrawal syndrome, The rationale for the usefulness of these agents has followed two basic directions. One direction has been to find effective central nervous system depressants which, by their cross-tolerance to alcohol, would theoretically be effective in the treatment of acute withdrawal. This has been emphasized by Isbell et al. (1955). The other direction has been the use of major and minor tranquilizers to calm and sedate patients. The former presumably attacks the underlying mechan i sm, the latter symptoms of anxiety, agitation and hallucinations.

Specifi c Treatment of Acute Alcohol Withdrawal
The data suggest that specific treatment applies to the impendi n g delirium t r emens than to delirium tremens reducing seizures than non-cross-tolerant drugs (Golbert et al., 1967;Kaim et al., 1969). · In the case of delirium tremens, the characteristic of cross-tolerance may not be as important and it is the opinion of many cl~nicians that the difference between the clinical efficacy of cross-tolerant and non-cross-tolerant drugs may be less critical than the experience of the clinician in detecting complications and correcting such problems as electrolyte imbalance (Gross et al., 1974;Victor, 1966). However, use of paraldehyde is still extensive and is vigorously supported for treatment of delirium tremens (Victor, 1966) . Although a recent su~ vey of physicians by Favazza and Martin (1974), found that chlordiazepoxide was favored by almost 2 to 1 as the drug of choice in the treatment of delirium tremens, other experimental work ers have found no difference between chlordiazepoxide and paraldehyde. This is of interest, since the major metabolite of paraldehyde is acetaldehyde.

Ethanol in the Treatment of Alcohol Withdrawal
Withdrawal reactions follow when chronic administration of a dependence produ cing drug stops, and the signs should therefore be relieved by reinstating the same drug or its pharmacological equivalent.  (1967), alcohol treatment does not always prevent the appearance of delirium tremens in man. Goldstein (1972b.) in mice and Ellis and Pick (1970b.) in monkeys, showed that ethanol does act as expected in reducing withdrawal severity. Goldstein (1972b.), has also shown that paraldehyde, meprobamate and barbiturates, which have similar pharmacological properties to ethanol, are also effective · in treating wi thdra~l in mice.

Comparison of Major and Minor Tranguilizers in Acute Alcohol Withdrawal
A comparative study of chlordiazepoxide, paraldehyde and haloperidol found that in the treatment OI uncomplicated acuLe alcohol withdrawal in man the rate of improvement was signiricantly greater with chlordiazepoxide over the long run (fourth day of observation), however, during the first 48 hours all drugs worked effectively with no significant difference between them (Gross et al., 1974).
Other major tranquilizers have been tested in the treatment of alcohol withdrawal. The use of cnlorpromazine · or promazine were compared wiLh paraldehyde and/or chlordiazepoxide in the treatment of delirium tremens (Kaim et al., 1969;Thomas and Freedman, 1964). In all cases chlorpromazine and promazine were markedly inferior. While promazine was no different than chlordiazepoxide in several symptoms other than delirium tremens, promazine failed to suppress convulsions (Chambers and Schultz, 1965). Thomas and J2 Freedman (1964) and Golbert et al. (1967) reported an alarming increase in mortality after promazine compared to paraldehyde or chlordiazepoxide. These results are in agreement with Goldstein (1972b.), who found that administration of promazine or chlorpromazine increased the severity of the withdrawal in ethanol dependent and withdrawn mice. Although Goldstein (1972b.), found chlordiazepoxide, diazepam and long-acting barbiturates highly effective in reducing withdrawal signs in mice, it was also reported that a significiant increase in mortality in mice treated with these long-acting drugs. The cause for the increased mortality was unknown and it was suggested that the disorder may have been one which is routinely corrected in a clinical situation, such as electrolyte or fluid imbalance. However, more seriously they may add to the brain damage caused by several days of intoxication and due to their cross-tolerant nature be equivalent to further days of intoxication and subsequently increase the withdrawal severity (Goldstein, 1972b.).
It appears that the clinical use of drugs is a very complex problem. Although, ,paraldehyde and chlordiazepoxide appe a r to emerge as consistently effective treatments, clinic a l management appears to have at least as much importance (Gross et al., 1974).

WITHDRAWAL AGGRESSION
Rats made physically dependent upon morphine display intense aggression during withdrawal without any other stimulation . This spontaneous aggression is enhanced by direct and indirect acting dopamine receptor stimulants, such as apomorphine and amphetamine and is blocked by the narcotic methadone or the dopamine receptor blocking neuroleptic haloperidol (Puri and Lal,197J).

It has been
proposed that morphine withdrawal aggression indicates the presence of dopamine receptor supersensitivity (Puri and Lal,197J). Apomorphine is known to be a direct dopamine receptor stimulator (Anden ~al., 1967;Ernst, 1967) and capable of inducing aggression itself, but at doses several fold higher than doses which intensify morphine withdrawal a ggression (Gianutsos, 1974). Dopamine receptor supersensitivity appears to be latent for protracted periods of up to at least JO days after withdrawal of morphine, demonstrated by intense agg ression in morphine dependent and withdrawn rats after JO days (Gianutsos etal., 1974b). The involvement of dopamine receptor supersensitivity in the production of aggression has been further supported by evidence that chronic blockade of dopamine receptors by the neuroleptic haloperidol results in increased sensitivity to apomorphine-induced aggression (Gianutsos et al., 1974a.).

J8
Determination of Blood Ethanol Levels: The assay procedure was that of Jones et al. (1970).
Rats were removed from the inhalation chamber and anesthestized with ether and a small blood sample collected from the tail vein in a heparinized vial.
A sample of 100 ul was . deproteinized with perchloric acid (4.9 ml, J.4% The reaction mixture was then incubated at J0°C in a constant temperature bath wi~h shaking for 10 minutes. The reaction mixture was then allowed to sit at room temperature for 15 minutes at which time the absorption was measured at J40 mu. The optical density, after subtraction of a non-ethanol blank value, was proportional to the concentration of ethyl alcohol in the blood.
where, X is ethanol/mg/ml: Y is . optical density; b is the Y intercept and M is the slope.
Ethanol Intoxication: The animals were exposed continuously for 5 or 7 days in the ethanol vapor chamber to an air-ethanol mixture obtained by mixing two streams of air; one directly to the chamber at a rate of 5.0 liters/min. and another bubbled through 9J% ethanol in a gas-washing bott~e at a rate of from 0.45 liters/min to 0.95 liters/min. · Rats were exposed to ethanol at a specific rate for the first 24 hours followed by gradual increases in ~he  Jones et al., (1970) was used. All animals were exposed to ethanol vapors in groups of six rats. Prior to exposure and every 24hours thereafter all animals were weighed and injected with pyrazole (68 mg/ kg, i.p.), except on the final day when weight was recorded but no pyrazole was administered . Goldstein and Pal (1971), found that pyrazole stabilizes the blood ethanol levals in mice inhaling ethanol vapors as well as inhibiting ethanol metabolism as shown by Theorell .£,:£al., (1969) andLester et al., (1968).
The air-ethanol flow-rates and daily doses of pyrazole maintained blood ethanol levels in 5 DAY LOW exposed rats at 0.8J ± 0.09 mg/ml/blood after 24 hours to 1.80 + 0.05 mg/ml/blooa after 120 hours of ethanol inhalation.
In 5 DAY HIGH exposed rats levels were 0 . 78 ± 0.14 mg/ml/blood after 24 hours to 1.98 + 0.16 mg/ml/blood after 120 hours i!.:..._.. __ __ 42 of ethanol inhalation. In 7 DAY HIGH exposed rats levels were 0.93 ~ 0.20 mg/ml/blood after 24 hours to 2.19 + 0.14 mg/ml/blood after 168 hours of ethanol inhalation. Table 1 shows the mean blood ethanol levels on each day of ethanol inhalcttio·n in groups inhaling ethanol under each of the three protocols. Since, both ethanol vapor concentration and pyrazole are inc r easing during ethanol inhalation it is not possible, from these retrospective comparisons, to conclude that pyrazole itself is not responsible for the increasing blood ethanol levels. However, Goldstein (1972a.); has shown that pyra zole does not cause increases in the blood       were counted and recorded at regular in"tervals.  (Table J), after withdrawal from the 5 DAY LOW protocol was relatively mild. The peak in-

55
tensity occurred after 24 hours of withdrawal with a median score of 4.5. The peak intensity of the ethanol withdrawal syndrome in rats after withdrawal from either the 5 DAY HIGH or 7 DAY HIGH protocols occurred at J6 hours of withdrawal with median scores of 6.0 and 7.5, respectively. The peak intensity of the ethanol withdrawal syndrome in rats exposed to the 5 DAY LOW protocol was significantly less than rats exposed to the 5 DAY HIGH or 7 DAY HIGH protocols (P< 0.001 Mann-Whitney U Test).
The peak intensity of the 5 and 7 DAY HIGH protocols were not · signiI icantly different.
Therefore, the 5 DAY HIGH protocol was selected for most studies, since the longer inhalation protocol did not significantly increase the withdraw~l intensity. Goldstein and Pal (1971), have shown that some ethanol withdrawal signs can occur at low levels of intensity in un~reated and pyrazole treated mice. Therefore, control rats were administered pyrazole . for 5 days and · control rats which were not pretreated were observed ana. rat· ed as were ethanol withdrawn rats.
These resul . ts are also seen in Figure     2student's "t" Test.
."• ·.,,I. less than untreated controls their we.ight loss was signif'icantly less than r~ts treated with only pyrazole. Data expresse.d as weight change (Table 4)    treated rats (0---0) and untreated rats (~) were observed for one hour for headshakes. Untreated rats were observed at one time period. 5 DAY HIGH and pyrazole treated rats were observed at six time periods over a 72 hour period.

J. D-Amphetamine-Induced Aggression in Ethanol Withdrawn
Rats D-Amphetamine was administered (i.p.) to rats withdrawn 72 hours after inhalation of ethanol vapors (5 DAY HIGH) or to 'rats treated for 5 days with pyrazole (68 mg/kg/ day) or to rats administered only air in the inhalation chamber for 5 days. It was found that after administration of ct-amphetamine to ethanol withdrawn rats the most consistent and intense aggression was · seen 60-120 minutes after injection . Therefore, this time period was selected for measurement of amphetamine-induced aggression. Table   lJ  2 N = number of groups, each group contains 3 rats. 31.ethal to 5/6 rats tested.

Rats
Rats which had previously fought at 72 hours of ethanol withdrawal after either apomorphine or ct-amphetamine were housed individually until "the seventh day of withdrawal.
These rats were then administered either apomorphine 3significantly greater than saline treated rats Student's "t" Test.        In most cases the number of animals was not sufficient to achieve statistical significance and it was not feasible to increase the numbers solely for study of mortality during ethanol withdrawal. However, in one extreme case a dose of 160 mg/kg chlordiazepoxide was administered which resulted in 75% mortality, which was significantly greater than rats withdrawn after exposure to the 5 DAY HIGH protocol and left untreated during ethanol withdrawal.
Since, a dose of chlordiazepoxide 160 mg/kg proved to be si gnificantly toxic to rats undergoing ethanol withdrawal, this s a me dose was administered (i.p . ) to untreated control rats.
As can be seen in the second part of  (Isbell et al., 1955;Newman, 1941).
However, the biochemical mechanisms subserving increased tolerance are unknown, but two general mechanisms have been postulated: an enhanced rate of metabolism and/or an increased degree of cellular tolerance or adption to ethanol in the central nervous system. Both, experimental animals (Hawkins et al., 1966) and man (Mendelson~ al., 1966) develop increased rates of ethanol metabolism following chronic administration. The increased ethanol metabolism in experimental animals has been correlated with increased hepatic alcohol dehydrogenase activity (Hawkins et~., 1966;Mendelson~ al., 1965). However, changes in the rate of ethanol metabolism can not adequately explain the degree of tolerance observed (Mendelson, 1971). Furthermore, LeBlanc et al. (1969), showed that tolerance after several doses of ethanol was not associated with an increased metabolic rate and suggested some form of cellular adaption as the basis of the tolerance seen. Sleeping time (narcosis) can be altered by increased elimination (Lal and Shah, 1968) and/or decreased sensitivity of the central nervous system (ex. hyperexcitability) (Patel and Lal, 1973).
In our experiments tolerance to ethanol was measured as a reduction in the duration or an increase in the onset  . Preliminary experiments demonstrated that a dose of 5.5 g/kg, i.p. proved fatal to 6/8 rats treated, while a dose of 4.5 g/kg, i.p.
induced narcosis in only 4/8 rats treated. Therefore, a dose of 5.0 g/kg, i.p. was selected for induction of· ethanol narcosis.
Although, it is usually common practice to assign a maximum score to animals w~ich fail to recover, some animals died shortly after injection, while others never recovered and subsequently died. Since, the number of deaths in each experimental group (5/18 air + saline, 5/18 air + pyrazole and 6/23 ethanol + pyrazole) were similar these animals were omitted f rom the study. From a reduction in the duration of ethanol induced narcosis or an increase in onset time, as seen in our experiments, it is not possible to separate metabolic from c e ll u J.ar tolerance.
The occurrence of withdrawal signs upon cessation of ethanol administration is evidence of physical dependence.

Inhalation of ethanol vapors along with daily injections
of an alcohol dehydrogenase inhibitor pyrazole (68 mg/kg, i.p.) has been shown to produce ethanol physical dependence in mice (Goldstein and Pal, 1971; Littleton~ al., 1 9 74). Goldstein and Pal (1971), developed a method for rating the intensity of the ethanol withdrawal syndrome .,·.  (Goldstein, 1972b.;. Majchrowicz (1973), outlined the withdrawal signs in rats made physically depenqent upon ethanol by daily intubations, but no .effort was made to measure their intensity. Although, Roach et al., (1973) Unlike the development of alcoholism in man, the production of physical dependence on ethanol in animals is very rapid, ranging from a few days (Goldstein and Pal, 1971) to several months (Falk, 1972). For the purpose of this study, a modification of the technique developed by Goldstein and Pal (1971), was adopted.
It shares the disadvantages common to all f6rced-administration models, but provides advantages which are lacking in most . Q~her models. The Goldstein-Pal model allows the production of relatively large numbers of dependent animals in short time, which are necessary for meaningful and practical experimental studies. Furthermore, the inhalation method provides t he production of an environment which is identical for all experimental subjects within a group, such that although chamber ethanol concentrations may vary somewhat from group to group all animals within an experimental group are exposed to identical ethanol levels and only indiv i dual biological variation can effect the within g roup variation.
Justification for the use of pyrazole is necessary.
Pyrazole also has some synergistic action with ethanol on the central nervous system when the doses used are higher than those used in this research (Goldberg et al., 1972).
Pyrazole, at the doses used in this research are severalfold lower than the doses shown by Lester and Benson (1970), to be toxic in rats, therefore it is unlikely that pyrazole would produce toxic effects in our experiments. Furthermore, careful controlling of experiments should prevent against erroneous conclusions from synergistic actions of pyrazole and ethanol. Goldstein (1972a), used pyrazole to stabilize blood ethanol levels which markedly fluctuated when pyrazole was not used. These fluctuations resulted in high mortality during inhalation of ethanol vapors (Goldstein, 1972a). Roach~ al . (1973), produced physical dependence in rats using inhalation of ethanol vapors without pyrazole, however, the blood ethanol levels were highly variable as was the intensity of the withdrawal reaction.

102
Reliable detection of withdrawal signs as being present or absent can be done accurately (Mello, 1973) and carefully developed rating scales, such as the one developed by Goldstein (1972a.) for mice, can provide valuable infermation about the relative severity of the ethanol withdrawal reaction. Table 3 shows the ordinal rating scale used to measure the intensity of the ethanol withdrawal signs which are not readily measurable by quantitative measures.
Statistically meaningful inferences can be made from rating or "ranking" scales using non-parametric analysis (Siegel, 19 56) • Figure 8 represents the withdrawal intensity seen after three different exposure procedures carried out as preliminary experiments to determine the condi·tions sufficient for production of physical dependence. Goldstein (1972a), showed that the intensity of the alcohol withdrawal reaction was related to the total dose of alcohol administered. The results obtained in this study are in agreement with Goldstein's work, although no attempt was made to calculate the total dose of alcohol, since the overall purpose of this work was not comparison among treatments. This is supported by the following (see Table 1 10.3 rats exposed to the 5 and 7 DAY HIGH protocols. The 5 DAY HIGH protocol was selected for subsequent studies because the degree of physical dependence was satisfactory and the mortality during ethanol withdrawal was not excessive (see Table 18). Goldstein (1972a.), reported weight loss in mice after either ethanol or pyrazole treatment, but did not report any results of both ethanol and pyrazole treatment on weight loss. Littleton et al. (1974), reported weight loss in mice after pyrazole treatment whether or not ethanol was administered, however he did report that there was no weight loss after ethanol alone. Table 4 demonstrates the effect of pyrazole or pyrazole plus ethanol on the body weight of rats after five days of treatment. Preliminary experiments carried out earlier agreed with Littleton's work. Rats exposed to only inhalation of ethanol vapors for five days did not lose body weight, but did prevent any gain in body weight over this period of time.
As seen in Table 4 treatment of rats with pyrazole or ethanol plus pyrazole reduced body weight, however, ethanol administration had a sparing effect on the pyrazole-induced body weight loss, possibly due to the caloric value of the inhaled ethanol.
The withdrawal syndrome seen upon removal of a chronically administered physical dependence-producing drug is a dy namic process. Abstinence signs have been observed in man (Isbe l l et al., 1955;Mello and Mendelson, 1970) and in experimental animals (Goldstein, 1972a.), while bLood ethanol levels are still high. Majchrowicz (1973), has shown that the peak intensity of the withdrawal reaction  Figure 10). However, it can also be seen in Figure   10 that headshakes are the only ethanol withdrawal sign observed to b9 associated with the administration of pyrazole alone at levels significantly greater than untreated control rats. Majchrowicz (1973), using an ethanol intubation procedure without pyrazole for production of physical dependence in rats also reported shakes during ethanol withdrawal. Therefore, it is highly unlikely that pyrazole administration during ethanol inhalation is solely responsible for the increased occurrence of headshakes during ethanol withdrawal, although some synergistic action may be involved. As seen in Figure 11 tail-lifts reach their peak intensity at 24 hours after ethanol with- Withdrawal reactions follow when chronic administration of a dependence producing drug stops, and the signs of withdrawal shou~d therefore be relieved by reinstating the same drug or its pharmacological equivalent. Goldstein (1972b.) and Ellis and Pick (1970b.), showed that ethanol does reduce the severity of the ethanol withdrawal reaction. Since , the mechanism of ethanol physical dependence and the subsequent withdrawal reaction are not known it is not clear which signs are specifically due to ethanol withdrawal.
However, one may rule out signs which are not reduced by ethanol administration as being non-specific. As seen in As seen in Table 5 headshakes occurring during ethanol withdrawal are also significantly reduced by readministration of ethanol. Tail-lifts as seen in Table 6 were also sign i ficantly reduced by readministration of ethanol. years is well tolerated in rats (Zbinden, 1961) as well as 100 mg/kg/day (i.p.) for five days (Hoogland, 1966 should not produce the high mortality seen in ethanol withdrawn rats. Since, animals undergoing ethanol withdrawal probably suffer from other disorders (ex. electrolyte imbalance or fluid imbalance), which would normally be routinely handled in a clinical situation, these disorders may be at fault . However, in our experiments untreated controls were also subjected to administration of chlordiazepoxide (160 mg/kg, i.p.) , which resulted in 66.7% mortality and was not significantly less than ethanol withdrawn rats administered the same dose of chlordiazepoxide. Male Long-Evans strain rats may be more sensitive to the toxic effects of chlordiazepoxide. Walsh et al. (1970), proposed that the formation of morphine-like alkaloids from tetrahydropapaveroline formed from dopamine and its aldehyde metabolite may be responsible for the dependence liability of ethanol . This hy- However, it is interesting that some of the withdrawal signs seen during ethanal withdrawal are similar to those seen during morphine withdrawal in rats. Gianutsos et al. (1975), observed the -,..._ following withdrawal signs in morphine withdrawn rats: piloerection, wet shakes (with occasional headshakes, Gianuts·os, personal communication), weight loss, hypothermia , ptosis, writhing and aggression, which is enhanced by apomorphine and amphetamine . In our experiments with ethanol withdrawn rats piloerection, headshakes and aggression induced by apomorphine and d-amphetamine were observed. As proposed by Walsh et al. (1970) and Davis et al. (1970), the role, if any, that morphinelike alkaloids have may be very limited and localized (ex. ;.

109
of morphine, such as analgesia or resporatory depression may be involved in the effectiveness of morphine in reducirtg the ethanol withdrawal syndrome in rats. Respiratory depression may be especially important in the light that convincing evidence for a role of respiratory alkalosis in the etiology of delirium tremens in humans (Victor, 1973).
In order to more clearly establish a role for morphine-  . This spontaneous aggression is enhanced by directly (apomorphine) and indirectly (amphetamine) acting dopamine receptor stimuJating agents and is blocked by the narcotic, methadone and the dopamine receptor blocking neuroleptic haloperidol  • .
Prior administration of alpha-methyl-para-tyrosine blocks the effect of amphetamine, but not apomorphine (Puri and Lai, 1973). These data were interpreted to indicate the presence of dopamine-receptor supersensitivity in morphine dependent and withdrawn rats. Apomorphine is a known stimulator of dopamine receptors (Anden et al., 1967;Ernst, 1967) and capable of producing aggression itself, but at doses several fold higher than needed to intensify morphine withdrawal aggression (Gianutsos, 1974). It has also been shown that chronic blockade of dopamine receptors by the neuroleptic, haloperidol, renders rats supersensitive to small doses of apomorphine (Gianutsos et al., 1974a), which do not elicit aggression in normal animals (Gianutsos, 1974). As seen in Table 11 the intensity of aggression induced .by ·apomorphine in ethanol withdrawn rats increases with the duration of ethanol withdrawal. Apomorphine-induced aggression in ethanol withdrawn rats was most intense at 72 hours of withdrawal.  It is believed that the deaths and the intensity of the aggression, not the lack of it, was responsible for the decreased rearing and vocalizations seen after a dose of 5.0 mg/kg apomorphine. This is borne out in Table 12 where the data for aggression af-  . As seen in Table 13 administration of ct-amphetamine to rats withdrawn from ethanol for 72 hours induces aggression. Interestingly, doses of ct-amphetamine in non-ethanol exposed rats does not induce aggression, even when doses which were lethal were administered.
These results indicate sensitivity to ct-amphetamine in ethanol withdrawn rats that can not be simulated in non-ethanol dependent rats, unlike apomorphinei n d uced aggression. Gianutsos et al. (1974b.), showed that morphine withdrawal a ggression was still present after protracted periods of withdra wal. As seen in Table 14 ethanol withdrawn rats remain sensitive to apomorphine and ct-amphetamine for at least seven days after withdrawal. These data again indicate s'imilarities between ethanol and morphine withdrawal in rats. · As seen in Tables 15, 16 and  Unfortunately, the effects of ethanol on neuroamine uptake, storage and release of catecholamines in the central nervous system is not clear (Friedhoff and Miller, 1973) and many conflicting reports are present in the literature.
Many of the conflicting results may stem from the differences occurring after acute compared to chronic administration of ethanol as well as the dosage administered (Friedhoff and Miller, 1973). One of the effects of acute ethanol administration to rats is the production of narcosis to which tolerance develops · (Friedhoff and Miller, 1973; this research). Administ ra tion of several biogenic amines, , I ~-...'...Jt;I~ 115 including dopamine, has been shown to prolong ethanol narcosis (Rosenfeld, 1960). Therefore, if increased mobilization of dopamine or other catecholamines occurs in the mediation of ethanol-induced narcosis, then continuous administration of ethanol might result in decreased production of dopamine by either repression of biosynthetic enzymes or negative feedback (Friedhoff and Miller, 1973). This could serve to reduce levels of available dopamine and restore normal levels of arousal in the face of continued ethanol administration (Friedhoff and Miller, 1973). This could also result in dopamine receptor sensitivity that would be unmasked upon cessation of ethanol administration.
Recently, the conflicting reports on catecholamine turnover in the literature have been explained by Hunt and Ma·j chr owicz ( 1974). Hunt and Majchrowicz ( 1974), have shown that after a single oral dose of ethanol (5.0 g/kg) to rats the turnover of brain norepinephrine is increased, while the turnover of dopamine is unaffected during the first few hours after treatment.
After the first few hours after ethanol administration the turnover of both norepinephrine and dopamine are decreased (Hunt and Majchrowicz, 1974). In alcohol dependent rats, whe~her intoxicated or undergoing withdrawal, the turnover of norepinephrine is increased, while that of dopamine is decreased (Hunt and Ma jchrowicz, 1974). At this time the mechanism by which ethan ol may bring about these changes in catecholam i n e turnover is not known. However, an hypothesis of " .  (1974), and the reduced cyclic adenosine monophosphate re-sponse to norepinephrine in brain slices of rats chronically fed ethanol (French~ al., 1974). This hypothesis proposes that, since norepinephrine exerts an inhibitory effect in the brain which tends to limit the spread of audiogenic seizure discharge in the rats, then convulsions and tremors seen during ethanol withdrawal in rats may be due to the subsensitivity of adrenergic receptors in the brain. This statement has been supported by the evidence of Goldstein (1973), that drugs which deplete brain catecholamines or block alpha or beta receptors aggravates ethanol withdrawal seizures in mice. Furthermore, the aggression seen in ethanol withdrawn rats, as reported in this research, may be due to decreased turnover and release of dopamine, resulting in supersensitivity of dop a mine receptors, which is • ----·~_....:...,1..1!·.....__ ·----· · --· --.. _., ----·--~.L ___ __.   1  10  13  3  25  5  37  1  2  5  14  D  26  3  38  2  3  D  15  5  27  3  39  0  4  8