Changes in monoamine concentrations in mouse brain associated with ethanol dependence and withdrawal

Effects of withdrawal from chronic intermittent ethanol vapor on the level and circadian periodicity of running-wheel activity in C57BL/6J and C3H/HeJ mice

BACKGROUND

Alcohol withdrawal is associated with behavioral and chronobiological disturbances that may persist during protracted abstinence. We previously reported that C57BL/6J (B6) mice show marked but temporary reductions in running-wheel activity, and normal free-running circadian rhythms, following a 4-day chronic intermittent ethanol (CIE) vapor exposure (16 hours of ethanol vapor exposure alternating with 8 hours of withdrawal). In the present experiments, we extend these observations in 2 ways: (i) by examining post-CIE locomotor activity in C3H/HeJ (C3H) mice, an inbred strain characterized by high sensitivity to ethanol withdrawal, and (ii) by directly comparing the responses of B6 and C3H mice to a longer-duration CIE protocol.

METHODS

In Experiment 1, C3H mice were exposed to the same 4-day CIE protocol used in our previous study with B6 mice (referred to here as the 1-cycle CIE protocol). In Experiment 2, C3H and B6 mice were exposed to 3 successive 4-day CIE cycles, each separated by 2 days of withdrawal (the 3-cycle CIE protocol). Running-wheel activity was monitored prior to and following CIE, and post-CIE activity was recorded in constant darkness to allow assessment of free-running circadian period and phase.

RESULTS

C3H mice displayed pronounced reductions in running-wheel activity that persisted for the duration of the recording period (up to 30 days) following both 1-cycle (Experiment 1) and 3-cycle (Experiment 2) CIE protocols. In contrast, B6 mice showed reductions in locomotor activity that persisted for about 1 week following the 3-cycle CIE protocol, similar to the results of our previous study using a 1-cycle protocol in this strain. Additionally, C3H mice showed significant shortening of free-running period following the 3-cycle, but not the 1-cycle, CIE protocol, while B6 mice showed normal free-running rhythms.

CONCLUSIONS

These results reveal genetic differences in the persistence of ethanol withdrawal-induced hypo-locomotion. In addition, chronobiological alterations during extended abstinence may depend on both genetic susceptibility and an extended prior withdrawal history. The present data establish a novel experimental model for long-term behavioral and circadian disruptions associated with ethanol withdrawal.

Serotonin, testosterone and alcohol in the etiology of domestic violence

In a previous study we administered the panicogenic agent sodium lactate to a select group of perpetrators of domestic violence and comparison groups. Results of that study showed that perpetrators exhibited exaggerated lactate-induced fear, panic and rage. In this current study, we compared the cerebral spinal fluid (CSF) concentrations of 5-hydroxyindoleacetic acid (5-HIAA) and testosterone obtained from perpetrators of domestic violence and a group of healthy comparison subjects. All subjects were assessed for DSM-III-R diagnoses. Perpetrators with alcohol dependence (DV-ALC) (n=13), perpetrators without alcohol dependence (DV-NALC) (n=10) and healthy comparison subjects (HCS) (n=20) were clinically assessed using the Spielberger Trait Anxiety, Brown-Goodwin Aggression Scale, Buss Durkee Hostility Inventory and Straus Conflict Tactics. Following an overnight fast and bed rest, subjects received a lumbar puncture to obtain CSF concentrations of 5-HIAA and testosterone. Perpetrators scored significantly higher on measures of aggression than HCS. DV-NALC had significantly lower concentrations of CSF 5-HIAA and higher Straus Conflict Tactics (CT) physical violence scores than DV-ALC and HCS. DV-ALC had significantly higher concentrations of CSF testosterone than DV-NALC. DV-ALC also had significantly higher Straus CT physical violence scores than HCS. DV-NALC and DV-ALC differed on 5-HIAA concentrations, testosterone concentrations, Straus CT physical violence scores and alcohol dependence. These results suggest that DV-NALC and DV-ALC groups could have different biological mechanisms mediating domestic violence.

Damaging effects of the calcium paradox are reduced in isolated hearts from ethanol-dependent rats: paradoxic effects of dihydropyridine drugs

Previous experiments showed that isolated hearts from ethanol-exposed rats show a marked increase in sensitivity to anoxic myocardial damage, and we suggested that this may be due to excess calcium entry through L-type voltage-operated calcium channels (L-VOCCs). To challenge this hypothesis, we investigated the effect of ethanol treatment ex vivo on a damaging stimulus, the "calcium paradox," which is associated with removal of calcium from the perfusate. Adult male Sprague-Dawley rats were exposed to intoxicating concentrations of ethanol for 6-10 days by inhalation. Isolated hearts from these animals were perfused with Krebs-Henseleit buffer by using a modified Langendorff technique, and the calcium paradox induced by a 10-min period of perfusion with calcium-free buffer, followed by reperfusion with calcium-containing buffer. Compared with controls, hearts from ethanol-exposed rats were significantly protected against myocardial damage, as shown by a marked reduction in release of intracellular proteins (lactate dehydrogenase, creatine phosphokinase, and myoglobin) during the reperfusion phase. These indices of myocardial damage were modified by the presence of the dihydropyridine (DHP) calcium channel antagonist nitrendipine (10(-6) M) and the DHP L-VOCC activator Bay K 8644 (10(-7) M) in the perfusate during the calcium paradox. Paradoxically, both drugs appeared to increase the damaging effects of calcium-free perfusion, with this effect being generally greater in the preparations from ethanol-exposed rats. As a result, the difference between these hearts and those from control rats was reduced, although a significant degree of protection against the calcium paradox remained. The results support the hypothesis that long-term exposure to ethanol in vivo produces marked alterations in the toxic effects of changes in myocardial calcium concentration. The increased sensitivity to DHP drugs of isolated hearts from ethanol-treated rats is consistent with previous experiments showing increased DHP radioligand-binding sites in these tissues.

Increased sensitivity to damaging effects of hypoxia and anoxia of isolated hearts from rats after prolonged exposure to ethanol: apparent protection by nitrendipine

The studies described here investigate whether pathologic states that are thought to cause myocardial damage through excess calcium entry (i.e., hypoxia and anoxia) indeed cause greater damage in hearts from ethanol-exposed animals, and whether L-type voltage-operated calcium channels (L-VOCCs) are implicated. Adult male Sprague-Dawley rats were exposed to intoxicating concentrations of ethanol vapor for 6-10 days, and their isolated hearts compared with those of control animals in a Langendorff perfusion system. Hypoxia was induced by perfusion with Krebs-Henseleit buffer, which had not previously been bubbled with oxygen; anoxia was produced by perfusion with buffer bubbled with nitrogen. On reperfusion with oxygenated buffer, evidence of myocardial damage during the hypoxic/anoxic period was obtained by the release of intracellular proteins into the perfusate. After hypoxia, release of myoglobin (MYO) was significantly greater from hearts from ethanol-exposed rats than from controls; other indices of myocardial damage also were increased by hypoxia but did not differ significantly between treatment groups. After anoxic perfusion, release of lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) as well as MYO were all markedly and significantly increased from ethanol-exposed hearts compared with those from control rats. The role of L-VOCCs in this damage was assessed with the calcium channel antagonist nitrendipine (10(-6) M) present in the perfusing buffer immediately before and during the anoxic stimulus. This completely reversed the situation so that preparations from ethanol-exposed rats now showed a reduced release of intracellular proteins compared with hearts from controls. Comparisons with absolute values from the previous experiments suggest that nitrendipine increased release of LDH and CPK from control hearts with little effect on these indices from ethanol-exposed hearts. However, in the case of anoxia-induced MYO release, nitrendipine markedly and significantly reduced this in hearts from ethanol-treated rats but had only a very small effect on the same parameter in controls. The results strongly suggest increased pathologic effects of hypoxia/anoxia in hearts from ethanol-exposed rats. This increased sensitivity may be at least partly a consequence of increased numbers of L-VOCCs in this tissue.

Effect of calcium, Bay K 8644, and reduced perfusion on basic indices of myocardial function in isolated hearts from rats after prolonged exposure to ethanol

We previously reported findings consistent with a marked upregulation in functional L-type voltage-operated calcium channels (L-VOCCs) in hearts obtained from rats exposed over the long term to ethanol. These experiments were undertaken to establish whether detrimental effects on cardiac function were associated with excess calcium entry into the myocardium in these hearts. Isolated hearts from adult male Sprague-Dawley rats received intoxicating concentrations of ethanol for 6-10 days by inhalation, were perfused with Krebs-Henseleit buffer by a modified Langendorff technique, and several functional parameters were assessed continuously. In some experiments, the calcium concentration in the perfusate was first reduced from the physiologic range (1.2 mM) to 0.15 mM and then increased in a step-wise fashion to 4 mM. In other experiments, hearts were exposed to buffer containing concentrations of the L-VOCC activator, (+/-)Bay K 8644, increasing from 10(-9) to 10(-6) M. These perfusion protocols were repeated in hearts from treated animals subject to reduced coronary flow because of induction of partial left ventricular ischemia. There were some close similarities in the effects of these different stimuli. When the calcium concentration in the perfusate exceeded a physiologic level, there were signs of decreased function relative to controls in the hearts from ethanol-exposed rats. Thus R-wave amplitude and systolic pressure were lower, diastolic pressure also was reduced, but heart rate was elevated above that of controls. Similarly the presence of (+/-)Bay K 8644 in the perfusate caused a decrease in systolic and diastolic pressure and an increase in heart rate in hearts from ethanol-exposed rats. When cardiac perfusion was reduced in vitro by inflation of a balloon in the left ventricle, some of the effects of excess calcium and (+/-)Bay K 8644 were reproduced in control hearts. However, imposition of this "ischemic" stress did not appear to exacerbate the effects of prior exposure to ethanol. In general, in control hearts, indices of contractility were increased across the range of calcium concentration or by perfusing with (+/-)Bay K 8644. Hearts from ethanol-exposed rats, however, showed no further increase in these parameters once physiologic levels of calcium were exceeded, or showed inhibition of contractility in the presence of (+/-)Bay K 8644. The results are consistent with calcium entry through L-VOCCs in hearts from ethanol-exposed animals having detrimental effects on cardiac function once physiologic levels are exceeded. However, it is possible that these channels also may be involved in maintenance of cardiac function at hypocalcemic levels.

Effects of prolonged exposure to ethanol in vivo on functional parameters and sensitivity to nitrendipine in the isolated rat heart

This study investigated the possibility that previously reported marked upregulation of binding sites for the dihydropyridine calcium channel antagonist nitrendipine in heart tissue during the development of ethanol dependence in the rat may represent functional L-type voltage-operated calcium channels (L-VOCCs). Isolated hearts obtained from adult Sprague-Dawley rats, which received intoxicating concentrations of ethanol for 6-10 days, by inhalation, were perfused with Krebs-Henseleit solution in the Langendorff mode. Basic measurements of cardiac function were compared with hearts from control rats not exposed to ethanol vapor. In another study, concentration-response curves were constructed for nitrendipine at concentrations in the range of 10(-10)-10(-6) M for hearts obtained from control and ethanol-exposed animals. Changes in measured cardiac parameters such as R-wave amplitude, heart rate, diastolic and systolic pressure, and (+)dP/dt(max) and coronary flow were recorded. All comparisons were made between preparations set to a similar left ventricular end-diastolic pressure. Under these conditions, there were no significant differences in R-wave amplitude, but isolated hearts from ethanol-dependent rats showed significantly greater indices of myocardial contraction than did controls. These included increased systolic and developed ventricular pressure and increased (+)dP/dt(max). Coronary flow also was significantly greater in hearts from ethanol-dependent rats compared with controls. Heart rate was higher in the alcohol-exposed group, but this difference did not achieve significance. When nitrendipine was added to the perfusate at concentrations between 10(-10) and 10(-6) M, hearts from ethanol-dependent animals showed a greater sensitivity to the effects of the drug on heart rate and systolic pressure. Effects on R-wave amplitude and (+)dP/dt(max) were less clear but also suggested a greater sensitivity to nitrendipine in hearts from ethanol-exposed rats. Effects on coronary flow were small and did not differ significantly between preparations from control and ethanol-dependent rats. The results suggest that the increase in Bmax of DHP binding previously observed in hearts from ethanol-dependent animals might represent an increase in L-VOCCs, which alters physiologic function, and pharmacologic responses in the isolated heart. These changes may represent the exposure of an adaptive mechanism designed to overcome the generally depressant effects of ethanol on cardiac function in vivo.

Alcohol withdrawal and dopamine receptor sensitivity after prolonged abstinence

1. Forty-four male inpatients suffering from moderate to severe alcohol dependence (DSM-III-R and ICD-10) as well as 14 healthy controls entered this study. Individuals were classified according to the severity of their withdrawal symptoms during detoxification i.e. group 1) no withdrawal, group 2) autonomic hyperactivity, group 3) withdrawal delirium and group 4) controls. 2. During the 6th week of treatment, that is, when all patients were recovered, controlled abstinent, and several weeks away from the end of their withdrawal syndrome, dopamine receptor sensitivity was neuroendocrinologically assessed by stimulating human growth hormone (HGH) with apomorphine (APO). 3. In a repeated measures model ANOVA, the four groups differed significantly in their HGH release. However, when excluding the controls from the analysis and focusing on alcoholics only (group 1 - 3), the significant difference disappeared. Covariates such as age, weight, quantity of drinking and duration of dependence were not related to the dependent variable. 4. In conclusion, the first significant result (with controls) reflects a blunted HGH response in alcoholics. It confirms earlier reports. The second, non significant result with the alcohol dependents only, suggests that the severity of withdrawal is not reflected by the amount of HGH released. Therefore, in alcoholics, a reduced dopamine receptor function after six weeks of abstinence, as neuro-endocrinologically assessed with apomorphine, seems to be related to alcohol dependence rather than to the severity of alcohol withdrawal.

Macrophages are a major source of acetaldehyde in circulating acetaldehyde-albumin complexes formed after exposure of mice to ethanol

C57BL mice were depleted of macrophages by an intravenous injection of liposome-encapsulated dichloromethylene diphosphonate (DCMDP), and control mice were uninjected or injected with empty liposomes. One day after injection, a proportion of the DCMDP-treated and control mice was continuously exposed to ethanol vapor for 4 days. Albumin fractions were separated from the sera of both ethanol-unexposed and ethanol-exposed animals and tested for cytotoxicity against a monolayer of A9 cells using two indicators of cytotoxicity: detachment of adherent cells and a decrease in the ability of cells to reduce tetrazolium. The results show that, in mice exposed to ethanol, macrophages are a major source of the acetaldehyde in circulating cytotoxic acetaldehyde-albumin complexes and presumably also of free acetaldehyde.

Serotonin and alcohol intake, abuse, and dependence: findings of animal studies

Despite a relatively large body of literature on the role of the neurotransmitter serotonin (5-hydroxytryptamine, or 5-HT) in the regulation of alcohol intake, the functional significance of serotonergic neurotransmission and its relationship to alcohol intake, abuse, and dependence remains to be fully elucidated. In part two of this review, the experimental (animal) data is summarized along two lines: the effects of serotonergic manipulations on the intake of alcohol, and the effects of acute and chronic alcohol intake, as well as the withdrawal of chronic alcohol, on the serotonergic system. It is concluded that serotonin mediates ethanol intake as a part of its larger role in behavior modulation, such that increases in serotonergic functioning decrease ethanol intake, and decreased serotonergic functioning increases ethanol intake. Ethanol produces transient increases in serotonergic functioning that activate the mesolimbic dopaminergic reward system. The results are discussed in light of recent theories describing the regulatory role of serotonin in general behavior.

Circadian variations in plasma monoamine metabolites level in alcoholic patients: a possible predictor of alcohol withdrawal delirium

1. Alcohol withdrawal symptoms in 17 alcoholics were classified into two groups according to the severity of their symptoms, and circadian variations in their plasma 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid (HVA) levels during the alcohol withdrawal and the abstention periods were compared with those in normal controls by two-way ANOVA. 2. Circadian variations in plasma 5HIAA level in alcoholic patients manifested severe alcohol withdrawal symptoms and exhibited phase advances in both the withdrawal and the abstention periods and significantly higher levels in the abstention period. 3. Circadian variation in plasma HVA in the abstention period in alcoholics showed severe withdrawal symptoms demonstrating significantly higher levels compared with normal controls. 4. These findings suggest that the serotonergic and dopaminergic activity may vary depending on the severity of alcohol withdrawal symptoms and the measurement of circadian variations in plasma 5HIAA and HVA levels could possibly be used as a predictor of hardly predictable alcohol withdrawal delirium.

Circadian variation in plasma homovanillic acid level during and after alcohol withdrawal in alcoholic patients

Alcohol withdrawal symptoms in alcoholics were objectively evaluated and classified into three groups according to the severity of their symptoms, and circadian variation in their plasma homovanillic acid (HVA) concentrations was determined at three different intervals after cessation of drinking. The subjects studied were 19 male alcoholic patients and five age-matched healthy male volunteers. Circadian variation in plasma HVA was compared between each patient group and the control group by two-way ANOVA. In the sympathetic overactivity (SO) group comprising nine patients and in the clouding of sensorium (CS) group comprising five patients, plasma HVA concentrations on the 2nd and 3rd day and on the 6th and 7th day after cessation of drinking were low but recovered almost normal levels on the 21st and 22nd postcessation day. The delirium tremens group (DT) comprising five patients, however, showed significantly higher plasma HVA than the control group except on the 6th and 7th postcessation day. The higher plasma HVA in the DT group indicates that there is some sort of preparatory state whereby dopamine metabolism is involved in the appearance of hallucinations at alcohol withdrawal and can possibly be used as a predictor of otherwise hardly predictable delirium tremens.

Serum prolactin increase induced by ethanol--a dose-dependent effect not related to stress

The effect of moderate ethanol doses (0.5 and 1 g/kg body weight) on serum prolactin (PRL), cortisol, epinephrine and norepinephrine concentrations was measured in a double-blind, placebo-controlled study. Eight healthy male volunteers participated. Blood was with drawn twice before, and 30 min, 60 min, 90 min and 120 min after oral ethanol intake. The higher ethanol dose, but not the lower dose, significantly increased PRL concentrations. Concentrations of cortisol, epinephrine and norepinephrine were not changed by either dose. Thus, the effect of ethanol on PRL appears to be dose-dependent and not stress-related.

Prenatal ethanol exposure alters immune capacity and noradrenergic synaptic transmission in lymphoid organs of the adult mouse

Clinical and experimental evidence indicates that exposure to alcohol in utero is associated with altered immune capacity. The mechanisms underlying such abnormalities are not clear. However, the suggestion that reciprocal interactions between the immune and the nervous systems are necessary for a competent immune response may be relevant. This work examined the consequences of prenatal ethanol exposure on cellular immune responses and noradrenergic synaptic transmission in lymphoid organs of the adult C57B1/6 mouse. Pregnant mice were fed a liquid diet containing 25% of the calories as ethanol (4.8% w/v) or pair-fed an isocaloric equivalent of this diet throughout gestation, followed by foster-nursing the neonates on normal dams. As young adults, mice exposed to ethanol prenatally displayed immunologic and selective neurochemical changes: (1) depressed ability to produce cellular immune responses, including contact hypersensitivity and a local graft-vs-host response, and (2) altered noradrenergic synaptic transmission, including enhanced norepinephrine turnover, and a reduction in norepinephrine levels and beta-adrenoceptor density in the thymus and spleen, but not the heart. However, both the integrity and compartmentation of noradrenergic nerve fibres in the spleen were intact. It is suggested that altered noradrenergic synaptic transmission selectively in lymphoid organs may contribute to the impaired immune capacity associated with fetal alcohol exposure.

Platelet serotonin decrease in alcoholic patients

This study investigated the platelet 5-HT levels and their changes according to different physiological and pathological factors in 30 young alcoholic patients (16 alcohol abusers and 14 alcohol-dependent subjects) and 26 healthy controls. Platelet 5-HT levels were determined by a fluorescent-ortho-phthalaldehyde assay. The mean platelet 5-HT levels obtained in patients during withdrawal and after 2 weeks of abstinence were significantly lower than in controls. Presence of positive history of impulse control disorders (ICD) influenced the mean platelet 5-HT levels in patients. These preliminary results suggest that the platelet 5-HT level decrease observed in alcohol-dependent patients mostly free from ICD and in alcohol abusers mostly affected by ICD might result from comparable neurobiological mechanisms. However, the age of onset of alcohol dependence might depend on psychological functioning features.

Effect of ethanol on androgen receptors in the anterior pituitary, hypothalamus and brain cortex in rats

The purpose of this study was to investigate ethanol-induced changes in androgen receptor sites in the anterior pituitary, hypothalamus, and brain cortex. Young adult male King-Holtzman rats were fed for 5 months a nutritionally complete liquid diet, with ethanol or isocaloric sucrose constituting 36% of the total calories. Androgen receptor sites were measured by sucrose density gradient and charcoal assay using tritiated dihydrotestosterone (DHT). Scatchard plot analysis of the data revealed that apparent dissociation constants of DHT-receptor complex for the anterior pituitary, hypothalamus, and brain cortex from alcohol-fed animals were estimated to be 0.7 +/- 0.13, 0.6 +/- 0.16 and 0.9 +/- 0.15 nM, respectively. These values are identical to those of their isocaloric controls. The concentrations of cytosol androgen receptors of the pituitary, hypothalamus, and brain cortex from alcohol-fed rats were 8.0 +/- 1.2, 6.2 +/- 1.0 and 4.9 +/- 0.7 fmol/mg protein, respectively. This represents about a 34, 24, and 22% reduction when compared to the values of the isocaloric control animals. In contrast to control rats, neither castration nor androgen or LHRH replacement to castrated alcohol-fed rats altered an alcohol-induced reduction of androgen receptor contents. Serum LH and testosterone levels were significantly decreased in alcohol-fed rats but these hormone levels were increased by administration of LHRH or norepinephrine. Such reduction of androgen receptors, serum LH and testosterone, but enhancement of these hormone levels by treatment with neurohormone and neurotransmitter in these animals suggests that ethanol exerts an adverse effect on the hypothalamic-pituitary unit and the neurotransmitter-hypothalamic hormone relationship, resulting in impairment of the androgen-induced sexual events and a suppression of the pituitary gonadotropin secretion.

Alpha-2-adrenoceptor function in alcohol withdrawal: a pilot study of the effects of iv. clonidine in alcoholics and normals

Central alpha-2-adrenoceptor function was studied in seven withdrawing alcoholics and compared with seven normal controls using the clonidine challenge test. The alcoholic group had significantly elevated basal levels of blood pressure and plasma 3-methoxy-4-hydroxy-phenyl glycol. The percentage of fall in blood pressure produced by clonidine was blunted in the alcoholics. There was disruption of the neuroendocrine effects of clonidine on growth hormone release. Physiological indices of withdrawal, in particular plasma 3-methoxy-4-hydroxyphenyl glycol and blood pressure correlated with measures of previous withdrawal experiences, supporting the idea that kindling might occur with repeated episodes of withdrawal.

Hepatotoxicity of ethanol in mice

Mice continuously exposed to ethanol vapour (for up to 19 days) developed fatty change in the liver (from 2 days onwards) and lesions resembling those of alcoholic hepatitis in man (from 5 days onwards). They also showed biochemical evidence of liver cell damage. Sera from ethanol-treated animals contained immunoglobulins that bound to the hepatocytes of ethanol-treated but not of control animals suggesting that exposure to ethanol was followed by an immunological response to a hepatocyte neo-antigen. In addition, such sera were cytotoxic in an in-vitro assay, and on Sephacryl S-300 gel filtration the cytotoxic activity eluted together with albumin molecules.

Haematological abnormalities in mice continuously exposed to ethanol vapour

Mice exposed to high concentrations of ethanol vapour (25-38 mg/l of inhaled air) for 24 h develop leucopenia, neutropenia, lymphopenia, monocytopenia and thrombocytopenia but not anaemia or macrocytosis. Their bone marrows usually give normal deoxyuridine-suppressed values and contain normal numbers of granulocyte-macrophage progenitor cells and slightly reduced numbers of megakaryocytes. Mice exposed to lower concentrations of ethanol vapour (10-25 mg/l of inhaled air) for 20-43 days develop thrombocytopenia only and, like the mice exposed for 24 h, do not develop anaemia or macrocytosis. The bone marrows of mice exposed to ethanol for 24 h or for 20-43 days, did not show either megaloblastic or sideroblastic erythropoiesis. The data suggest that the ethanol-treated mouse may provide a useful model for the investigation of the mechanisms underlying some but not all of the ethanol-induced haematological changes seen in humans.

Inhibition of fast phase calcium uptake and endogenous norepinephrine release in rat brain region synaptosomes by ethanol

The effects of ethanol on fast phase calcium (Ca2+) uptake and endogenous norepinephrine release were assessed simultaneously in KCl-depolarized synaptosomes isolated from rat hypothalamus, brainstem and cerebellum. Incubation of brain regional synaptosomes with ethanol resulted in a concentration-dependent inhibition of Ca2+ uptake after 1 s of depolarization. Hypothalamic synaptosomes were most sensitive to the inhibitory effect of ethanol on voltage-dependent Ca2+ uptake and brainstem synaptosomes were least sensitive. Endogenous norepinephrine release from synaptosomes was not altered by addition of ethanol in vitro at any of the concentrations examined (25-200 mM). Chronic ethanol administration resulted in an adaptation to the inhibitory effect of ethanol on Ca2+ uptake into hypothalamic synaptosomes but did not alter the inhibitory effect of ethanol on Ca2+ uptake into brainstem or cerebellar synaptosomes. Fast phase, voltage-dependent norepinephrine release was inhibited by ethanol added in vitro but only in synaptosomes isolated from hypothalami and cerebella of chronically treated animals. Brain regional norepinephrine concentrations were unaltered by chronic ethanol administration. These results suggest that chronic ethanol treatment may alter the coupling of Ca2+ entry with norepinephrine release in some noradrenergic neurons. Effects of ethanol on synaptosomal Ca2+ entry and norepinephrine release differ depending on the brain region.

Cyclic AMP-dependent protein phosphorylation is reduced in rat striatum after chronic ethanol treatment

Endogenous protein phosphorylation by cyclic AMP-dependent protein kinase was found reduced in striatal membranes obtained from chronic ethanol-treated rats. Experiments using an exogenous substrate show that the decreased response is due to a deficiency in the phosphorylating activity of the cyclic AMP-dependent protein kinase and not to a lack of endogenous substrate for phosphorylation.

Clinical neuroendocrinology and neuropharmacology of alcohol withdrawal

A number of alcohol research groups have measured anterior and posterior pituitary hormones, the endogenous opiates, CNS peptides, and putative neurotransmitters during alcohol withdrawal. The data are often complex and contradictory, though a number of themes have emerged. Activity of the hypothalamic-pituitary-adrenal axis (HPA) is increased during chronic alcohol exposure and appears to remain altered for at least 2 to 4 weeks after cessation of drinking. There is increased turnover of norepinephrine and enhanced binding of CNS adrenergic receptors. By contrast, there are decreases in CNS activity of select endogenous opiates and GABA. Other CNS compounds that may play a role in alcohol withdrawal are prolactin, thyrotropin-releasing hormone (TRH), vasopressin, cyclic 3'5'-adenosine monophophate (cAMP), Delta-sleep-inducing peptide (DSIP), and iron. Despite many studies in humans and animals, the roles of CNS dopamine and serotonin in withdrawal remain unclear. A number of peptides, including cholecystokinin (CCK), neurotensin, and bombesin, have been shown to interact with the CNS actions of alcohol and may play a role in alcohol withdrawal. Inadequate work has been performed on acetylcholine (ACh), human growth hormone (HGH) and luteinizing hormone (LH). Studies of the recently identified GABA-benzodiazepine-barbituate receptor complex indicate that this system is likely to be involved in the pathophysiology of alcohol withdrawal. Perturbation studies with corticotropin-releasing factor (CRF) and TRH (with measures of ACTH and cortisol and TSH and prolactin, respectively), may identify patients with withdrawal-related autonomic dysfunction.

Brain catecholamines during ethanol administration, effect of naloxone on brain dopamine and norepinephrine responses to withdrawal from ethanol

The variations in brain dopamine (DA) and norepinephrine (NE) levels after ethanol administration have been studied in rats. Acute ethanol administration significantly decreased brain DA and NE levels. After chronic ethanol intake no changes were observed in brain catecholamines. Ethanol withdrawal induced significant decreases in DA and NE concentrations in the brain. The administration of naloxone, antagonist of opiate receptors, blocked the effects of ethanol deprivation on brain catecholamines. These data suggest that endogenous opioids may be involved in the ethanol-withdrawal syndrome.

Biochemical basis of alcoholism: statements and hypotheses of present research

Experimental results and theoretical considerations on the biology of alcoholism are devoted to the following topics: genetically determined differences in metabolic tolerance; participation of the alternative alcohol metabolizing systems in chronic alcohol intake; genetically determined differences in functional tolerance of the CNS to the hypnotic effect of alcohol; cross tolerance between alcohol and centrally active drugs; dissociation of tolerance and cross tolerance from physical dependence; permanent effect of uncontrolled drinking behavior induced by alkaloid metabolites in the CNS; genetically determined alterations in the function of opiate receptors; and genetic predisposition to addiction due to innate endorphin deficiency. For the purpose of introducing the most important research teams and their main work, statements from selected publications of individual groups have been classified as to subject matter and summarized. Although the number for summary-quotations had to be restricted, the criterion for selection was the relevance to the etiology of alcoholism rather than consequences of alcohol drinking.

Increased activity of Ca2+-dependent enzymes of membrane lipid metabolism in synaptosomal preparations from ethanol-dependent rats

In synaptosomal fractions of rat brain the activities of phospholipase A2 and the phospholipid base-exchange enzymes are highly dependent on external Ca2+ concentrations. Their activity is inhibited by the presence of 50 mM ethanol in vitro. Administration of ethanol to rats by inhalation causes a progressive increase in the activity of these enzymes in synaptosomal preparations at all Ca2+ concentrations studied. The increased activity of these enzymes persists in preparations from rats undergoing a physical syndrome of withdrawal from ethanol. The addition of ethanol in vitro to preparations from animals that had received ethanol in vivo had no significant effect on enzyme activity. The results are discussed in relation to the possible roles of membrane lipid metabolism and synaptic Ca2+ sensitivity in ethanol tolerance and physical dependence.

Effect of ethanol in vitro and in vivo on Ca2+-activated metabolism of membrane phospholipids in rat synaptosomal and brain slice preparations

Phospholipase C (PLC) activity was measured by the incorporation of [3H]-inositol into lipids and by the breakdown of [3H]-inositol-labelled phosphatidylinositols (PI) and polyphosphatidylinositols (PPI) to [3H]-inositol phosphates; phospholipase A2 (PLA2) activity by the breakdown of [3H]oleic acid-labelled phosphatidylcholine [( 3H]PC) to [3H]oleic acid and the enzymes of phospholipid base exchange (PLBE) by the incorporation of [14C]serine into membrane lipids. The activities of these enzymes in rat brain preparations were all increased by procedures which increase intracellular Ca2+, and were all inhibited to a varying extent by the presence of ethanol, 50 mM, in vitro. In contrast, the activities of PLA2 and PLBE enzymes were markedly increased in preparations from animals which had received ethanol chronically in vivo. Similarly, although the basal activity of PLC was only slightly increased in such preparations, depolarization induced the breakdown of a significantly greater fraction of radiolabelled PI than that which was obtained in control preparations. The results suggest compensatory alterations in the activity of Ca2+-activated enzymes of phospholipid metabolism in brain tissue during the continued presence of ethanol in vivo.

Alterations in Ca2+-dependent and Ca2+-independent release of catecholamines in preparations of rat brain produced by ethanol treatment in vivo

Compared to preparations from control animals, superfused striatal slice preparations from brains of rats treated chronically with ethanol released a significantly greater fraction of stored [3H] dopamine on depolarisation in 40 mM K+. Similarly, the electrically-evoked release of [3H]-norepinephrine from cortical slices and of [3H]-dopamine from striatal slices is also increased, although with this mechanism of depolarisation the change is significant only in the case of [3H] norepinephrine release. In contrast to this tendency to enhancement of Ca2+-dependent depolarisation-induced release, a reduced fraction of stored [3H]-catecholamines was released from these preparations by the indirect sympathomimetics tyramine and (+)-amphetamine. The catecholamine release induced by these indirect sympathomimetics is largely independent of external Ca2+ and the results are interpreted as suggesting that chronic alcohol treatment changes the distribution of catecholamine neurotransmitters between storage pools in the nerve terminal which do or do not require Ca2+ entry for release.

Role of tyrosine in the acute effects of ethanol on rat brain catecholamine synthesis

Acute ethanol administration exerts multiple effects on rat brain catecholamine synthesis, associated with corresponding changes in cerebral tyrosine concentration. Catecholamine synthesis is enhanced at 1 hr by an increased availability of circulating tyrosine to the brain after inhibition of liver tyrosine aminotransferase activity. Tyrosine hydroxylation in vivo and tyrosine hydroxylase activity measured in vitro are also enhanced at 1 hr. Catecholamine synthesis is inhibited at 2-4 hr when tyrosine availability to the brain is decreased because of an enhancement of liver tyrosine aminotransferase activity. Serum neutral amino acid concentrations are decreased at 5 hr. This is followed 1 hr later by normalization of cerebral catecholamine synthesis. By 8 hr after ethanol administration, the latter becomes enhanced because of increased cerebral uptake of tyrosine. Catecholamine synthesis is inhibited at 12 hr because of enhanced transamination of brain tyrosine. Tyrosine metabolism finally returns to normal at 16 hr after ethanol administration. These results are discussed in relation to previous work with ethanol, and to central and peripheral mechanisms of regulation of brain catecholamine synthesis.

Effects of ethanol on thermoregulation

Clinical reports of accidental hypothermia in alcohol intoxicated individuals exposed to low ambient temperature ( Paton , 1983) have generally been borne out by experimental studies in healthy volunteers. Small doses of ethanol, given to human subjects at normal ambient temperature (Ta), have very little effect on body temperature but a combination of large dose, low Ta and vasodilatation provoked by strenuous exercise, causes a sharp fall in rectal temperature. In experimental animals, the use of relatively larger doses of alcohol and more extreme temperatures, both above and below the thermoneutral zone, has shown that the effect of ethanol is essentially poikilothermic, i.e. an impairment of adaptation to both heat and cold. This effect has been studied in greater detail, in relation to each of the basic thermoregulatory processes. Though small doses of alcohol may increase the metabolic rate under some circumstances, the most common effect at low Ta is inhibition of shivering and therefore reduction of thermogenesis. At the same time it tends to cause increased heat loss by cutaneous vasodilatation. This makes for a greater feeling of comfort in the cold exposed subjects but increases in rate of fall of core temperature. The combination of decreased thermogenesis and increased heat loss, despite falling body temperature, is suggestive of a lowering of the set-point of the thermoregulatory control mechanisms. Consistent with this is a slight increase in ventilatory heat loss after low doses of ethanol but larger doses cause respiratory depression, so that heat loss through the lungs is minor. However, at high Ta ethanol caused hyperthermia in experimental animals and shows enhanced lethality, so that impairment of thermoregulatory effector mechanisms seems to be at least as important as change in set-point. Studies of the effects of ethanol on electrophysiological activity of single neurons in the pre-optic area and anterior hypothalamus (POAH), biochemical activities of neuronal membranes, hypothalamic blood flow, conventional neurotransmitters, amino acid putative neurotransmitters, neuropeptides, prostaglandins and inorganic ions have all failed so far to yield a clear comprehensive picture of the mechanisms by which ethanol affects thermoregulation. In each case, contradictory evidence has been obtained concerning the consequences of ethanol administration, whether by oral, intraperitoneal, intravenous, intracerebroventricular, or direct local (POAH) route.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of chronic ethanol administration on the composition of membrane lipids in the mouse

The relative proportions of the phospholipid fatty acids of erythrocyte membranes in mice were changed by chronic ethanol treatment and were not related to effects of the drug on nutrition, body temperature or experimental stress. Similar changes were observed using two different routes of ethanol administration and they did not reflect the metabolic effects of ethanol seen in the phospholipid fatty acids of whole liver. The observed increased content of saturated fatty acids and decreased content of polyunsaturated acids support the concept of adaptive changes taking place in the membrane during tolerance development to compensate for an increased membrane fluidity caused by ethanol. However, an increased content of the mono-unsaturated acid, octadecenoic (oleic), was found and there was no change in the cholesterol/phospholipid ratio. Other contrasting types of plasma membrane in mice showed different patterns of change in their phospholipid fatty acids during chronic ethanol administration. It is suggested that changes in membrane lipid composition could only partly account for an adaptation to ethanol-induced membrane disordering.

Inhibition of rat brain tryptophan metabolism by ethanol withdrawal and possible involvement of the enhanced liver tryptophan pyrrolase activity

1. Chronic ethanol administration to rats was previously shown to enhance brain 5-hydroxytryptamine synthesis by increasing the availability of circulating tryptophan to the brain secondarily to the NAD(P)H-mediated inhibition of liver tryptophan pyrrolase activity. 2. At 24h after ethanol withdrawal, all the above effects were observed because liver [NAD(P)H] was still increased. By contrast, all aspects of liver and brain tryptophan metabolism were normal at 12 days after withdrawal. 3. At 7--9 days after withdrawal, brain 5-hydroxytryptamine synthesis was decreased, as was tryptophan availability to the brain. Liver tryptophan pyrrolase activity at these time-intervals was maximally enhanced. 4. Administration of nicotinamide during the withdrawal phase not only abolished the withdrawal-induced enhancement of tryptophan pyrrolase activity on day 8, but also maintained the inhibition previously caused by ethanol. Under these conditions, the withdrawal-induced decreases in brain 5-hydroxytryptamine synthesis and tryptophan availability to the brain were abolished, and both functions were enhanced. Nicotinamide alone exerted similar effects in control rats. 5. It is suggested that ethanol withdrawal inhibits brain 5-hydroxytryptamine synthesis by decreasing tryptophan availability to the brain secondarily to the enhanced liver tryptophan pyrrolase activity. 6. The results are discussed in relation to the possible involvement of 5-hydroxytryptamine in dependence on ethanol and other drugs.

Monoamine metabolism in rat brain regions following long term alcohol treatment

Female Wistar rats (150--200 g) were treated with ethanol (15% w/v) for 21 days and compared with control rats given water. Ethanol administration produced a reduction of fluid and food consumption and changes in the metabolism of cerebral monoamines. There was an increase in serotonin (5-HT) turnover statistically significant in the striatum, and a decrease in noradrenaline (NA) turnover in ethanol rats as compared to controls. Endogenous NA levels were significantly increased in the diencephalon and dopamine (DA) levels were increased in the striatum. After inhibition of catecholamine synthesis with alpha-methyltyrosine (alpha-MT), NA depletion was significantly retarded but no changes in DA depletion were noted. DOPA accumulation after decarboxylation inhibition showed no significant change in any brain region studied.

Fatty liver and sudden death. A review

Alcoholism is associated with increased mortality from violent and nonviolent causes. The increase in nonviolent deaths is usually ascribed, at least in part, to "cirrhosis." In the majority of these deaths this implies fatty liver rather than true Laennec's cirrhosis. Studies of sudden nonviolent deaths illustrate the largely unrecognized and frequent occurrence of sudden death with autopsy findings limited solely to fatty liver. The mechanism(s) of these sudden fatty liver deaths is unknown. Several attractive theories attribute such deaths to ethanol withdrawal induced hypoglycemia or hypomagnesemia, pulmonary fat embolization from fatty liver, or other facets of the alcohol withdrawal syndrome, including ethanol dependent maladaptive derangements of neurotransmitters. All the theories of fatty liver death remain essentially untested, however, owing to uncontrolled postmortem conditions and the lack of awareness of fatty liver deaths within the scientific community.

Unsuitability of control sucrose or glucose in studies of the effects of chronic ethanol administration on brain 5-hydroxytryptamine metabolism

Chronic sucrose or glucose administration enhances 5-hydroxytryptamine synthesis in rat brain, as does ethanol. This suggests that the above sugars are not suitable for use as control treatments in studies of the chronic effects of ethanol on brain 5-hydroxytryptamine metabolism.

Cerebral blood flow and oxygen consumption during ethanol withdrawal in the rat

The ethanol withdrawal syndrome in man and animals is characterized by signs of CNS hyperactivity although a direct measurement of a physiological variable reflecting this CNS hyperactivity has never been performed in untreated man or in animals. We induced ethanol dependence in the rat by means of intragastric intubation with a 20% w/v ethanol solution, thus keeping the animals in a state of continuous severe intoxication for 3--4 days; during the subsequent state of withdrawal characterized by tremor, rigidity, stereotyped movements and general seizures a 25% increase in cerebral oxygen consumption (CMRO2) could be measured; this increase was not due to catecholamines originating from adrenal medulla as adrenomedullectomized animals showed a similar increase in CMRO2 (28%); the withdrawing animals showed a corresponding cerebral blood flow (CBF) increase. The elevated CMRO2 and CBF could be reduced to normal by administration of a beta-adrenergic receptor blocker (propranolol 2 mg/kg i.v.), and hence the increased CMRO2 during ethanol withdrawal could be related to catecholaminergic systems in the brain, e.g. the noradrenergic locus coeruleus system which is anatomically well suited as a general activating system. This interpretation is supported by the earlier neurochemical finding of an increased cerebral noradrenaline turnover during ethanol withdrawal. The exact mechanism underlying the increased cerebral oxygen consumption during ethanol withdrawal and the effect of propranolol on cerebral function during this condition remains to be clarified.

The rapid development of functional tolerance to ethanol by mice

A method is described in which the development of tolerance to ethanol in individual mice can be measured during the inhalation of ethanol vapour. This method has been used with two behavioural end-points, loss of righting reflex and loss of rotarod performance. It demonstrates that, in the adult male, TO Swiss mouse, peak tolerance, in which approximately 2 X the original effective blood ethanol concentration is required to produce the behavioural end-point, can develop in 3--5 h. After this time the ability of the animals to perform normally in the presence of continued high concentrations of ethanol in blood begins to fall. The results are discussed in relation to current concepts of tolerance to central nervous system depressant drugs.

Adaptive changes in cerebral blood flow and oxygen consumption during ethanol intoxication in the rat

Cerebral blood flow (CBF) and oxygen consumption (CMRO2) were measured during acute and long-term ethanol intoxication in the rat. The purpose was to investigate whether the adaptive changes (development of tolerance) occurring in the CNS during ethanol intoxication were associated with changes in CBF and/or CMRO2. Consistent with other studies we found that acute severe ethanol intoxication (median blood alcohol concentration (BAC = 5.4 mg/ml)) caused a significant decrease in CBF and CMRO2. After 3-4 days of severe intoxication (BAC of 6.6 mg/ml) these physiological variables were less affected indicating that functional tolerance had developed: CMRO2 and CBF during acute ethanol intoxication were 9.3 ml/100 g/min and 60 ml/100 g/min respectively; after the long term intoxication period these variables reached 11.2 ml/100 g/min and 78 ml/100 g/min respectively, i.e. values not significantly lower than those of the control group. After induction of hypercapnia (PaCO2 about 80 mmHg) CBF increased by 360% in the control group; in the acutely intoxicated group CBF increased by only 127% and in the long term intoxicated group by 203% indicating that the cerebrovascular CO2-reactivity had also adapted to the ethanol intoxication. It is concluded that adaptive changes of the CNS to chronic ethanol intoxication comprise alterations in CMRO2, CBF and cerebrovascular reactivity.

Influence of chronic ethanol vapor inhalation on hepatic parenchymal and Kupffer cell function

This report evaluates the influence of chronic ethanol vapor inhalation on various facets of liver function as well as induction of hepatic and pulmonary pathology in rats. Chronic ethanol inhalation is associated with minimal hepatic dysfunction, but pronounced induction of metabolic tolerance.

Enhancement of rat brain tryptophan metabolism by chronic ethanol administration and possible involvement of decreased liver tryptophan pyrrolase activity

1. Chronic ethanol administration enhances rat brain 5-hydroxytryptamine synthesis by increasing the availability of circulating tryptophan to the brain. This increased availability is not insulin-mediated or lipolysis-dependent. 2. Under these conditions, tryptophan accumulates in the liver and apo-(tryptophan pyrrolase) activity is completely abolished, but could be restored by administration of regenerators of liver NAD+ and/or NADP+. 3. All four regenerators used (fructose, Methylene Blue, phenazine methosulphate and sodium pyruvate) prevented the ethanol-induced increase in liver tryptophan concentration and the increased availability of tryptophan to the brain. 4. It is suggested that the enhancement of brain tryptophan metabolism by chronic ethanol administration is caused by the decreased hepatic tryptophan pyrrolase activity. The results are briefly discussed in relation to previous work with ethanol. 5. Fructose enhances the conversion of tryptophan into 5-hydroxyindol-3-ylacetic acid in brains of ethanol-treated rats, whereas Methylene Blue inhibits this conversion in both control and ethanol-treated animals.