Changes in dopamine receptor sensitivity in humans after heavy alcohol intake

Alpha-Synuclein in Alcohol Use Disorder, Connections with Parkinson's Disease and Potential Therapeutic Role of 5' Untranslated Region-Directed Small Molecules

Alpha-synuclein (α-Syn) is a 140-amino acid (aa) protein encoded by the Synuclein alpha SNCA gene. It is the synaptic protein associated with Parkinson's disease (PD) and is the most highly expressed protein in the Lewy bodies associated with PD and other alpha synucleopathies, including Lewy body dementia (LBD) and multiple system atrophy (MSA). Iron deposits are present in the core of Lewy bodies, and there are reports suggesting that divalent metal ions including Cu2+ and Fe2+ enhance the aggregation of α-Syn. Differential expression of α-Syn is associated with alcohol use disorder (AUD), and specific genetic variants contribute to the risk for alcoholism, including alcohol craving. Spliced variants of α-Syn, leading to the expression of several shorter forms which are more prone to aggregation, are associated with both PD and AUD, and common transcript variants may be able to predict at-risk populations for some movement disorders or subtypes of PD, including secondary Parkinsonism. Both PD and AUD are associated with liver and brain iron dyshomeostasis. Research over the past decade has shown that α-Syn has iron import functions with an ability to oxidize the Fe3+ form of iron to Fe2+ to facilitate its entry into cells. Our prior research has identified an iron-responsive element (IRE) in the 5' untranslated region (5'UTR) of α-Syn mRNA, and we have used the α-Syn 5'UTR to screen for small molecules that modulate its expression in the H4 neuronal cell line. These screens have led us to identify several interesting small molecules capable of both decreasing and increasing α-Syn expression and that may have the potential, together with the recently described mesenchymal stem cell therapies, to normalize α-Syn expression in different regions of the alcoholic and PD brain.

Sensation seeking, alcoholism and dopamine activity

Sensation seeking scale (SSS) scores were determined in 15 alcohol dependent men with a positive family history for alcoholism (FHP), in 15 alcohol dependent men with a negative family history for alcoholism (FHN) and in 15 well-matched healthy male controls (CONTR). Both FHPs and FHNs suffered from longlasting alcohol dependence meeting ICD-10 and DSM-III-R diagnostic criteria. Dopamine activity was neuroendocrinologically assessed by measuring the amount of growth hormone released after stimulation with the dopamine receptor agonist apomorphine. Planned comparisons within a one-way ANOVA yielded significantly elevated levels of boredom susceptibility (BOS) in both FHPs and FHNs against CONTRs. SSS total scores, while approaching statistical significance, were elevated in FHPs only. Partial correlations (controlling for age, body weight, alcohol intake and duration of dependence) were calculated to examine the relationship between SSS and dopamine activity. Among the SSS subtraits, BOS revealed the highest correlation in each group. However, only in CONTRs did the relationship between BOS and dopamine activity reach statistical significance.

Oxyhalogen-sulfur chemistry: kinetics and mechanism of oxidation of chemoprotectant, sodium 2-mercaptoethanesulfonate, MESNA, by acidic bromate and aqueous bromine

The oxidation of a well-known chemoprotectant in anticancer therapies, sodium 2-mercaptoethanesulfonate, MESNA, by acidic bromate and aqueous bromine was studied in acidic medium. Stoichiometry of the reaction is: BrO3(-) + HSCH2CH2SO3H → Br(-) + HO3SCH2CH2SO3H. In excess bromate conditions the stoichiometry was deduced to be: 6BrO3(-) + 5HSCH2CH2SO3H + 6H(+) → 3Br2 + 5HO3SCH2CH2SO3H + 3H2O. The direct reaction of bromine and MESNA gave a stoichiometric ratio of 3:1: 3Br2 + HSCH2CH2SO3H + 3H2O → HO3SCH2CH2SO3H + 6Br(-) + 6H(+). This direct reaction is very fast; within limits of the mixing time of the stopped-flow spectrophotometer and with a bimolecular rate constant of 1.95 ± 0.05 × 10(4) M(-1) s(-1). Despite the strong oxidizing agents utilized, there is no cleavage of the C-S bond and no sulfate production was detected. The ESI-MS data show that the reaction proceeds via a predominantly nonradical pathway of three consecutive 2-electron transfers on the sulfur center to obtain the product 1,2-ethanedisulfonic acid, a well-known medium for the delivery of psychotic drugs. Thiyl radicals were detected but the absence of autocatalytic kinetics indicated that the radical pathway was a minor oxidation route. ESI-MS data showed that the S-oxide, contrary to known behavior of organosulfur compounds, is much more stable than the sulfinic acid. In conditions where the oxidizing equivalents are limited to a 4-electron transfer to only the sulfinic acid, the products obtained are a mixture of the S-oxide and the sulfonic acid with negligible amounts of the sulfinic acid. It appears the S-oxide is the preferred conformation over the sulfenic acid since no sulfenic acids have ever been stabilized without bulky substituent groups. The overall reaction scheme could be described and modeled by a minimal network of 18 reactions in which the major oxidants are HOBr and Br2(aq).

Neurological complications of alcohol usage

The relationships between alcohol usage and a number of neurological syndromes are reviewed. These are often complex and incompletely understood. Multiple rather than single factors are the rule rather than the exception. The correct diagnosis may be missed particularly where the aetiological role of alcohol is overlooked. Multiple diagnoses are not uncommon. Issues of differential diagnosis and diagnostic procedures are discussed. Management, including a number of its pitfalls, is outlined.

Toxin-Induced Movement Disorders

Toxins can be cited as a cause of several movement disorders, but this association is rare and the resultant syndromes usually include additional signs that are not typical for the idiopathic movement disorders. Most instances of confirmed toxin-induced movement disorders show lesions on CT and MRI scans of cortical or subcortical structures. A common underlying element in these toxin-induced syndromes is the development of lesions primarily in the pallidum and striatum. Because many toxins result in lesions affecting these structures, a selective vulnerability to hypoxic or metabolic insults has long been postulated. The susceptibility of these structures may relate to a number of factors, including the pattern of oxidative metabolism, heavy metal concentration, vascular perfusion, and neuronal innervation. Finally, in addition to causing disability, certain neurotoxins have led to a better understanding of human disease through the development of research models. As an example, the MPTP model has not only provided an animal model to study therapeutic strategies in PD but has also contributed important insights into the mechanism of neuronal degeneration.

Alcohol-withdrawn animals have a prolonged increase in dopamine D2high receptors, reversed by general anesthesia: relation to relapse?

The biochemical basis for alcohol addiction and relapse is not known. Although ethanol promotes the release of dopamine like other drugs of abuse, many unknown factors remain to be investigated concerning the biochemical abnormalities which persist after ethanol drinking and which contribute to alcohol relapse. Although ethanol withdrawal is associated with enhanced sensitivity to dopamine in animals and humans, only minor changes in the striatal density of dopamine D2 receptors have been found in humans, and animals show a small reduction in striatal D2 receptors. But how can dopamine-related functions be increased in ethanol withdrawal in the face of an unchanged or reduced density of dopamine D2 receptors? Considering that ethanol sensitizes rats to amphetamine, and that the high-affinity state of D2, or D2High, is markedly increased in striata from amphetamine-sensitized rats, we measured the density of D2High in striata from rats withdrawn from ethanol. These sites were elevated by 360% (7.2 pmol/g) for at least 8 days after stopping ethanol and returned to normal levels of 2 pmol/g after 2 weeks of ethanol withdrawal. In addition, 1 h of deep general anesthesia given 5 days into withdrawal resulted in a normal level of D2High within 24 h. Because the D2High states are the functional form of D2, their elevated density in ethanol withdrawal may be related to ethanol relapse in humans. General anesthesia may alleviate aspects of alcohol or amphetamine abuse or psychosis associated with elevated D2High.

Pharmacokinetic-pharmacodynamic study of apomorphine's effect on growth hormone secretion in healthy subjects

Apomorphine (APO) stimulates growth hormone (GH) release via dopamine D2 receptors (DRD2). There is no specific study assessing the relationship between APO pharmacokinetic (PK) and the pharmacodynamic (PD) response e.g. GH release. The objective of the study is the PK-PD modelling of APO in healthy subjects. This is a randomized crossover study with s.c. administration of 5, 10, and 20 micro g/kg of APO in 18 healthy subjects. APO concentrations were modelled according to both a bi-compartmental model with zero-order absorption and a bi-compartmental model with first-order absorption. PK-PD relationship was modelled in accordance with the Emax Hill equation using plasma concentrations of APO calculated according to the bi-compartmental model with zero-order absorption. Modelled parameters were very similar to the experimental parameters. PK of APO was linear and there was no significant difference between the tested doses for AUC0--> infinity and Cmax (normalised to the dose 1 micro g/kg), t1/2alpha and t1/2beta. These parameters expressed as mean (CV%: SD/mean) were: 17.2 (26.9) ng/mL.min, 0.26 (33.3) ng/mL, 17.1 (54.2) and 45.2 (20.6) min, respectively (n = 53). An anticlockwise hysteresis loop (effect function of APO plasma concentration) appeared for each dose and each subject. The predicted and measured GH concentrations for all subjects and times were similar whatever the dose (P > 0.27). Emax values were 246 (121), 180 (107), 205 (139) ng/mL, respectively, and EC50 were 0.98 (48.1), 1.70 (62.3), 3.67 (65.2) ng/mL, respectively at dose 5, 10, and 20 micro g/kg (P < 10-4). APO and GH concentrations were predicted with good accuracy using bi-compartmental with zero-order absorption PK model and sigmoid Emax PD model, respectively.

Growth hormone response to placebo, apomorphine and growth hormone releasing hormone in abstinent alcoholics and control subjects

Abstinent alcoholics and control subjects were challenged with placebo (saline), growth hormone releasing hormone (GHRH) and apomorphine (APO). While both groups did not differ in their growth hormone response (HGH) to placebo and GHRH, the alcoholics revealed a significant lower HGH response to dopamine receptor stimulation with APO. These findings provide no evidence that in abstinent alcoholics HGH blunting after dopamine receptor stimulation could be related to an alteration at the pituitary level but they give neuroendocrinological support to the hypothesis of a lower dopamine receptor sensitivity in abstinent alcoholics.

Platelet monoamine oxidase (MAO) activity and alcoholism: is there a genuine association?

Monoamine oxidase (MAO) is a particle-bound flavoenzyme principally located in the outer mitochondrial membrane, which catalyzes the oxidative deamination of a variety of the amine transmitters in the central nervous system. There have been many reports from different groups around the world over the last 20 years that indicated a lower platelet MAO activity was associated with alcoholism. As there are multiple influences upon measured MAO activity, this article attempts to address each of the issues in turn for potential confounding of the reported association. These issues include: the duration of abstinence from alcohol, the substrate used for analysis, gender issues, association with different subtypes of alcoholics, the influence of other psychopathology, personality traits of alcoholics, the question of smoking, and proposed modes of transmission of MAO activity. The initial promise about MAO activity being a possible marker for alcoholism or a least a genetically predisposed subgroup has receded as the number of negative typology-based studies increases. The failure to account for a major confounding variable, e.g. smoking and other minor but possibly vital confounds in almost all these studies leaves the whole hypothesis open to criticism. However, the possible association between personality traits that might predispose to some if not all substances of addiction to low MAO activity may make it possible to reframe the hypothesized association in the setting of a generalized predisposition to addictions in particular, and to psychopathology in general. Nonetheless the association remains of great interest and may yet yield vital genetic and clinical information.

Decreases in dopamine receptors but not in dopamine transporters in alcoholics

It has been hypothesized that ethanol's actions on the dopamine (DA) system may participate in addiction. The purpose of this study was to evaluate the DA system in the brain of alcoholics. We evaluated 10 alcoholics and 17 nonalcoholics using positron emission tomography and [11C]raclopride to measure DA D2 receptors. In addition, in 5 of the alcoholics and 16 of the nonalcoholics, we also measured DA transporters with [11C]d-threo methylphenidate. The ratio of the distribution volumes in striatum to that in cerebellum, which corresponds to Bmax/Kd + 1, was used as model parameter of DA D2 receptor and transporter availability. Dopamine D2 receptor availability (Bmax/Kd) was significantly lower in alcoholics (2.1 +/- 0.5) than in nonalcoholics (2.7 +/- 0.6) (p < 0.05) and was not correlated with days since last alcohol use. Alcoholics showed DA transporter values similar to those in nonalcoholics. The ratio of DA D2 receptor to transporter availability was significantly higher in nonalcoholics (1.4 +/- 0.1) than in alcoholics (1.1 +/- 0.1) (p < 0.005). Alcoholics showed significant reductions in D2 receptors (postsynaptic marker) but not in DA transporter availability (presynaptic marker) when compared with nonalcoholics. Because D2 receptors in striatum are mainly localized in gamma-aminobutyric acid (GABA) cells these results provide evidence of GABAergic involvement in the dopaminergic abnormalities seen in alcoholics.

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.

Reduced dopaminergic function in alcoholics is related to severe dependence

With a view to the role of dopamine (DA) systems in reward processes and considering recent studies linking specific alleles at the DA-D2 receptor gene locus with alcoholism (especially with severe types) dopaminergic functions were evaluated in 49 alcoholics using growth hormone (GH) response to DA receptor agonist apomorphine (0.01 mg/kg subcutaneously). neuroendocrine testing was performed (during intoxication) at the time of admission to an inpatient alcohol treatment program and was repeated 7 days later (in a postintoxicated state). Patients underwent clinical examination, detoxification treatment and a subsequent rehabilitation program for abstinence including follow-up evaluation of outcome for 6 months. A two-factor analysis of variance (ANOVA) revealed a significant change of GH response (peak values corrected for baseline) over time (between intoxication and postintoxication; p < 0.001) and between abstainers and relapsers (p = 0.032). Relapse was also associated with paternal alcoholism, early onset of disease, and a more complete dependence syndrome and cerebellar atrophy. Standardized canonical discriminant coefficient was highest for reduced GH response compared to other relapse predictors in the model used. It is concluded that reduced GH response to dopaminergic stimulation corresponds to a progressed stage or syndrome of severe alcohol dependence; however, if reduced, dopaminergic function is one cause or consequence of addiction in this particular subgroup of patients that remains to be elucidated.

Evidence for reduced dopamine D2 receptor sensitivity in postwithdrawal alcoholics

Dopamine D2 receptor sensitivity was assessed in the postwithdrawal period in alcoholics. Growth hormone (GH) responses to dopamine D2 agonist bromocriptine were measured in eight DSM-III-R alcohol-dependent subjects who were 2 weeks or more postalcohol withdrawal. Their responses were compared with eight nonalcoholic controls. After an overnight fast, each subject received 1.25 mg of bromocriptine orally, and serial samples of GH were taken over a 3-hr period. There was a significantly blunted delta GH response (mean +/- SE) in the alcoholic group, 2.3 mU/liter (+/- 1.4) relative to controls, 7.7 mU/liter (+/- 1.2) (t = 2.96, df = 14, p = 0.01). There was a significantly blunted peak GH response (mean +/- SE) in the alcoholic group, 5.36 mU/liter (+/- 2.1) relative to controls, 9.04 mU/liter (+/- 5.0). This difference also reached statistical significance (t = 2.32, df = 14, p = 0.035). A repeated-measures ANOVA yielded a significant within-subjects effect of time [F(4,54) = 4.08, p = 0.0057], a significant within-subjects effect of group [F(1,14) = 5.6, p = 0.0329], and an almost significant group x time interaction [F(4,54) = 2.45, p = 0.056]. This result implies a relative dopamine D2 receptor subsensitivity in alcoholics in the postwithdrawal period.

Alcohol dependence, family history, and D2 dopamine receptor function as neuroendocrinologically assessed with apomorphine

Fifteen alcohol dependent men with an alcohol dependent first degree relative (i.e. family history positive or FHP), 15 well matched alcohol dependent men without a family history for alcohol dependence (i.e. family history negative or FHN), and 15 healthy controls (CONTR) participated in this study. The three groups were compared according to their postsynaptic D2 dopamine receptor function as assessed by growth hormone release after stimulation with the dopamine receptor agonist apomorphine. Statistical evaluation was done by planned comparisons within a one-way ANOVA. Alcohol dependent subjects significantly differed from CONTRs as long as family history was not taken into account (t(42) = 2.38; P = 0.022*). When differentiating according to family history, both FHPs and FHNs maintained a blunted growth hormone response. However, the difference between FHNs and CONTRs, though present, dropped out of statistical significance (t(42) = 1.65; P = 0.105); at the same time, the difference between FHPs and CONTRs became slightly stronger (t(42) = 2.47; p = 0.017*). In conclusion, our data give neuroendocrinological support to the assumption that a reduced D2 dopamine receptor function in alcohol dependent men is not only a state marker of residual heavy drinking but also a genetically determined trait marker.

Evidence for prolonged recovery of dopaminergic transmission after detoxification in alcoholics with poor treatment outcome

It has been hypothesized that dysfunction of dopaminergic neurotransmission is involved in the pathogenesis of alcohol addiction. Therefore, peripheral dopamine levels, sensitivity of central dopamine receptors (apomorphine-induced Growth Hormone (GH) secretion), and the inhibitory efficacy of G-proteins on adenylyl cyclase activity (as an indicator for dopamine D2-receptor coupled second messenger mechanisms) were measured in 45 alcohol-dependent patients before and after detoxification and in 10 healthy controls. The time needed to adjust to abstinence conditions differed between patients with good and poor treatment outcome. In subsequent abstainers, effects of alcohol withdrawal were already found during the first 24 hours of abstinence (normalisation of GH response, increases in dopamine levels and the inhibitory efficacy of G-proteins). During the next 7 days of abstinence, no more significant changes were observed in the assessed variables. In subsequent relapsers, no significant effect of acute ethanol withdrawal on the same measures was found. However, at day 8 of abstinence, increases in apomorphine-induced GH secretion (towards normalisation), in dopamine plasma levels, and in the inhibitory efficacy of G-proteins (towards above-normal levels) were observed. This retarded adjustment of dopaminergic signal transduction seems to reflect the relapse risk of treatment nonresponders.

Effect of haloperidol on measures of craving and impaired control in alcoholic subjects

We recently proposed that alcoholics suffer from a functional defect within the basal ganglia/limbic striatum or its modulation by dopaminergic projections from the ventral tegmentum, and that inhibition of striatal output caused by the prodopaminergic effects of alcohol ingestion induces or exacerbates craving and impaired control over alcohol consumption in alcoholic individuals. To test this hypothesis, 16 subjects with a diagnosis of alcohol dependence or abuse were studied in a double-blind, placebo-controlled experiment in which the effects of the D-2 antagonist haloperidol on measures of craving and impaired control were assessed before and after administration of a priming dose of alcohol. Subjects were pretreated with 0.015-0.025 mg/kg haloperidol (experimental condition) or 2 ml normal saline (control condition), and subsequently consumed 0.4-0.6 g/kg ethanol as their preferred alcohol-containing beverage. Significant increases in subjectively rated craving for alcohol and perceived difficulty resisting additional alcohol consumption occurred following the priming dose of alcohol when subjects were pretreated with saline. In contrast, no significant changes in reported ability to resist additional alcohol occurred when subjects were pretreated with haloperidol, and reported levels of craving decreased relative to baseline following haloperidol pretreatment. Subjects also consumed about 25% less optionally available alcohol when pretreated with haloperidol than when pretreated with saline. These findings support the hypothesis that craving and impaired control are induced or exacerbated by the prodopaminergic effects of alcohol consumption.

Further neuroendocrine evidence for reduced D2 dopamine receptor function in alcoholism

D2 dopamine receptor function, as assessed by growth hormone (GH) responses to apomorphine (APO; 0.18-0.24 mg i.v.), was investigated in 15 male alcoholics with reported long-term abstinence. Results from only nine subjects could be evaluated. These subjects had been heavy alcohol consumers for a mean of 15 +/- 10 years and had thereafter been abstinent for a mean of 7 +/- 6 years prior to the investigation. Eight male healthy subjects, all of whom were light social drinkers, were selected as controls. The maximum GH responses to APO were significantly lower in the alcoholics (5.8 +/- 5.8 mU/l) than in the controls (22.1 +/- 19.2 mU/l). This finding gives neuroendocrine evidence for reduced D2 dopamine receptor function in alcoholics with long-term abstinence.

Adaptive changes of dopamine-D2 receptors in rat brain following ethanol withdrawal: a quantitative autoradiographic investigation

The effect of subchronic treatment with two doses of ethanol (5 and 10 vol% drinking fluid) on the density of dopamine-D2 receptors was investigated at two different phases of withdrawal, namely 24 h and 5 days after the cessation of the ethanol application. The number of dopamine-D2 receptors was affected in regions receiving projections from both the substantia nigra as well as the ventral tegmentum. Twenty-four hours after the replacement of the ethanol solution by water, a dose-dependent decrease of D2 receptors was found in all regions (N. caudatus dorsalis, medialis and ventralis, N. accumbens lateralis and medialis, tuberculum olfactorium) and most of the analyzed planes [interaural 7.7-10.2 according to the atlas of Paxinos and Watson (35)]. At day 5 of withdrawal, the number of dopamine-D2 receptors of the animals treated with 5 vol% ethanol reached the level of water controls in most planes. In contrast, two- to three-fold higher numbers were detected in animals treated with the higher dose. Only in the most caudal parts of the investigated regions, was the number of receptors decreased with the higher dose. The mesocorticolimbic system seems to be less sensitive to the effects of ethanol than the nigrostriatal neurones. The findings of the present study suggest an increased activity of dopaminergic neurons with an adaptive reduction of dopamine-D2 receptors during the subchronic treatment with ethanol during the first day(s) of withdrawal. This phase is followed by a reduced turnover rate for up to 7 days (21). The reduced activity of dopaminergic neurones induces a compensatory increase of the number of receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

A rating scale for assessment of alcohol withdrawal psychopathology (AWIP)

For patients in alcohol withdrawal, there are several scales designed to assess physiological disturbances, but there seems to be a lack of scales for assessment of psychopathology. To develop and evaluate a rating scale for psychopathology, items from the Comprehensive Psychopathological Rating Scale (CPRS) were selected, and patients meeting the DSMR-III-R criteria for alcohol dependence (303.90) were rated on these items. The patients were divided into two groups according to the length of time passed since their last period of alcohol consumption. The groups are referred to as the group (n = 53) in early withdrawal, rated daily during 1 week and the group (n = 13) in late withdrawal, rated once a week for 7 weeks. To justify inclusion in the new scale, items had to either indicate psychopathology in at least half of the patients in one of the groups in withdrawal, or be sensitive to changes over time at a 0.1% level of significance. Seventeen items fulfilled one of these criteria. The scale was tested for inter-rater reliability in a new sample of patients (n = 30) in early withdrawal. Inter-rater reliability, as well as internal consistency, was found satisfactory. This new scale, capable of identifying psychopathology and changes over time, may be used alone or together with physiological scales to identify subgroups of patients undergoing withdrawal.

Neuroendocrine Evidence for Reduced Dopamine Receptor Sensitivity in Alcoholism

Postsynaptic dopamine (DA) receptor sensitivity was assessed during abstinence in 15 male patients with alcohol dependence. The DA receptor sensitivity was evaluated using growth hormone (GH) responses to the DA receptor agonist apomorphine (0.18-0.24 mg intravenously). The patients were cared for in an alcoholism treatment unit for the 2 months prior to the investigation. They were carefully controlled for sobriety during this period. Thirteen healthy men were used as controls. The maximum GH responses to apomorphine were significantly reduced in patients compared with those in the control group. The patients had a significantly higher proportion of blunted GH responses. The findings suggest reduced postsynaptic DA, possibly D2, receptor sensitivity in abstinent alcoholics. The question whether this abnormal DA receptor status is genetically determined or acquired after long-term alcohol consumption remains to be addressed.

Individual mood profiles in alcohol withdrawal

Daily self-reports of moods, using a Swedish Mood Adjective Check List with six bipolar dimensions, were performed in patients with alcohol dependence. One group (n = 13), consisting of inpatients in late withdrawal at a home for addicts, was studied for 6 weeks; another group (n = 12), consisting of outpatients in full remission, was studied for 1 week. The results of the ratings on the check-list were used to test a statistical model for its capacity to describe the individual courses of mood states during the recovery process. Time Series Analysis revealed that the individual courses of moods fitted an autoregressive statistical model and could thereby be summarized in numerical measures for individual baselines, amplitudes, and lengths of recovery. Such individual profiles of the alcohol recovery process, may be useful for both clinical and research purposes, making it possible, for instance, to predict points in time for an individual's recovery with respect to his total well-being, as well as the various dimensions of his mood states.

Neuroendocrine measures of dopaminergic function in chronic cocaine users

Plasma prolactin (PRL) and growth hormone (GH) levels are determined, in part, by the effects of dopamine (DA) at pituitary and hypothalamic DA receptors, respectively. To determine if chronic cocaine abuse alters dopaminergic activity, basal PRL and GH concentrations were measured in 16 male patients meeting DSM-III-R criteria for cocaine dependence (8 cocaine users and 8 cocaine + alcohol users) and 8 normal controls. In addition, the functional responsivity of DA receptors was assessed in the same group of patients by measuring the change in plasma PRL and GH concentrations following the administration of the direct-acting DA agonist, apomorphine (0.01 mg/kg, s.c.) or saline. No difference in basal plasma PRL and GH levels or plasma PRL and GH responses to apomorphine administration was found between the entire group of cocaine patients and normal controls. However, three of the cocaine patients had basal plasma PRL levels that were more than 2.5 SD greater than that of the normal controls, suggesting that some interference of dopaminergic inhibition of PRL secretion might be present in at least some cocaine users. Although baseline plasma PRL levels were elevated in a subgroup of cocaine users, these data do not support the hypothesis that chronic cocaine abuse produces consistent abnormalities in dopaminergic function at the pituitary or hypothalamus.

On the relative importance of D-1 vs. D-2 dopaminergic receptors in the control of audiogenic seizures in ethanol withdrawn rats

Bromocriptine, a mixed D-1/D-2 dopaminergic receptor agonist and SKF 38393, a D-1 specific agonist were found to alleviate the incidence and intensity of audiogenic convulsions in ethanol withdrawn rats. (+) and (-)3-PPP, putative D-2 autoreceptor agonists, were without effect in the test. SCH 23390, a D-1 specific antagonist did not influence seizure intensity in ethanol withdrawn or ethanol naive animals. It is suggested that D-1 receptors may play a role in convulsive response during ethanol withdrawal.

Alcohol withdrawal and mood

The usefulness of a self-report technique for description of mood was tested at various stages of alcohol withdrawal. The Mood Adjective Check List (MACL), consisting of 71 mood-associated adjectives and measuring 6 bipolar aspects of mood, was used. Three groups of alcohol-dependent patients (DSM-III-R) reported on their momentary mood states twice a day, respectively, during early withdrawal (n = 78), during late withdrawal (n = 13), and after full remission (n = 12). Significant improvement was found in all 6 mood dimensions during early withdrawal. Improvement in 3 basic mood dimensions was also found during late withdrawal, thus indicating a prolonged time of recovery. The reports given by patients in full remission showed no changes in mood over time. Relative to norm group values, significant differences were found in 4 of the 6 mood dimensions for patients in very early withdrawal. The present study shows that mood changes attributable to after-effects of alcohol intake can be assessed and described during various stages of withdrawal.

Inhibition of brain dopa-decarboxylase by RO 4-4602 infused ICV blocks alcohol drinking induced in rats by cyanamide

Following the stereotaxic implantation of chronic cannulae for intracerebroventricular (ICV) infusion, rats were given an alcohol preference test to establish their preferred concentration in comparison with water. After alcohol was removed, 15 mg/kg cyanamide was then injected subcutaneously for 4 days in order to maximize volitional intake of single solutions of alcohol, which in these animals ranged from 7 to 15%. The L-dopa-decarboxylase inhibitor benserazide (Ro 4-4602) injected subcutaneously twice daily in doses of 50-100 mg/kg failed to alter the rats' alcohol consumption either in terms of g/kg or proportional values. However, when given ICV twice daily in concentrations of 10 ng-2.0 micrograms per 5.0 microliters volume, benserazide attenuated the rats' alcohol drinking significantly. This reduction occurred in a dose-dependent manner in terms of both absolute and proportional intakes of alcohol. Pre-treatment of the animals with 1.0 microgram benserazide given ICV, when alcohol was removed from the test situation, did not abolish the subsequent ingestion of alcohol but its peripheral administration (50 mg/kg) enhanced drinking. These results suggest that the interference with the metabolic pathway of dopamine or serotonin synthesis, possibly through the mechanism of reduced formation of aldehyde adducts in the brain, markedly alters the pattern of voluntary drinking in the rat. Alternatively, benserazide could act by its central inhibition of aldehyde dehydrogenase, which in turn would concomitantly elevate levels of acetaldehyde and thereby reduce alcohol drinking.

Ethanol withdrawal alters apomorphine-induced motility

Acute administration of ethanol is accompanied by alterations in dopamine turnover and release, and chronic ethanol exposure is associated with changes in biochemical measures of dopamine receptor function. This paper presents data examining the effects of chronic ethanol exposure on behavioral responses to the dopamine receptor agonist apomorphine. Measurements of behavior were obtained through the use of an electronic motility monitor which permitted the quantification of movements in terms of their characteristic frequency components. Results are presented which indicate that apomorphine-induced movements with modal frequencies of 2 Hz and of 8-9 Hz are significantly increased during the 12 to 24 hr following ethanol withdrawal, suggesting an increase in the functional responsiveness of central dopaminergic systems.

The anxiolytic and anxiogenic actions of ethanol in a mouse model

The administration to mice of ethanol in the drinking water for 7 days modified exploratory activity (rearings/line crossings) in an anxiety testing box separated into white and black sections with an interconnecting door. During ethanol intake mice exhibited reduced anxiety responding, shown as increased rearings and line crossings in the white section, to which the mice are normally averse, with corresponding decreased behaviour in the black section. When naive mice were presented with a choice between normal drinking water and drinking water containing ethanol, they consumed sufficient of the latter to secure a full anxiolytic response, making up the total volume of fluid required by also drinking the former. A 48 h withdrawal from a 14 day treatment with ethanol caused a reversed profile of exploratory behaviour, directed preferentially at the black section of the test box, and indicative of an anxiogenic response. Diazepam, tiapride or clonidine given twice daily during withdrawal from ethanol could each secure a reduction in the withdrawal anxiogenesis. It is concluded that the simple model of anxiety described in the mouse may be useful for eludicating the mechanisms involved in the anxiolytic and anxiogenic potential of ethanol and may aid the search for novel agents having potential to suppress withdrawal anxiogenesis.

Apomorphine-induced hypothermia increases during ethanol withdrawal

Changes in several measures of dopamine function have been observed following acute or chronic ethanol exposure. The present study examined the effects of chronic ethanol exposure on the hypothermia following acute administration of the dopamine agonist apomorphine. Animals withdrawn from chronic ethanol exposure showed a significantly greater decrease in body temperature following apomorphine than did ethanol-naive controls, suggesting an increase in sensitivity to dopaminergic stimulation during ethanol withdrawal.

Apomorphine in the evaluation of dopaminergic function in man

1. Apomorphine (Apo), a short acting dopamine (DA) receptor agonist, stimulates growth hormone (GH) secretion, decreases prolactin secretion, induces yawning, penile erections and other physiological effects in man. An effect on behavior, movement disorders and alcoholism has also been described. 2. Apo-mediated responses are used to evaluate DA function in psychiatric and neurological disorders. Many of the studies in schizophrenia using the GH response to Apo as an index of central DA function are difficult to interpret because of failure to control for key variables. 3. The GH response to Apo is a useful system to evaluate the effects of various drugs including peptides which may not cross the blood brain barrier on DA function in man. 4. Apo is a potent sedative. Specific antimanic, antischizophrenic, and anticraving effects in alcoholics have not been convincingly demonstrated. Side effects of Apo and failure to use active placebo make double-blind studies difficult. 5. Apo improves parkinsonian symptoms and certain forms of reflex epilepsy but beneficial effects in other involuntary movement disorders requires further documentation. 6. Apo may be a useful agent to evaluate DA function in impotent patients and predict a therapeutic response to long-acting dopaminergic agents. 7. Impairment of DA function may play a role in diabetic impotence. 8. The development of a simple polygraphic method to monitor the yawning response to Apo may facilitate clinical studies on the basic physiology of yawning in man and the use of the yawning response as a measure of central DA function in schizophrenia and other clinical disorders. 9. The use of Apo with 18F-fluorodeoxyglucose positron emission tomography to examine regional DA function in man opens up a promising area of research. 10. Though long-acting orally active aporphine DA agonists and antagonists have been developed the problem of tolerance may limit their therapeutic potential.

Differential effects of chronic ethanol on apomorphine-induced locomotion, climbing and aggression in rats

Male Wistar rats were tested for apomorphine-induced locomotion, climbing and aggression after 3 week's intragastric ethanol (EtOH) treatment, 5 g/kg as 20% solution daily. The ability of apomorphine (APO) to elicit rearing (1 mg/kg i.p.) and climbing (0.5 mg/kg i.p.) was significantly suppressed in EtOH withdrawn animals. General locomotor activity in response to 1 mg/kg of APO i.p. did not differ between control and EtOH-treated groups. Affective aggression was checked in pairs of low-aggressive rats, i.e. resistant to the aggression inducing action of 10 mg/kg APO. No symptoms of aggression appeared in control animals whereas EtOH administered rats responded with marked aggression to APO. The different effect of chronic EtOH on responsiveness to APO in three behavioral models is discussed in terms of varying involvement of dopaminergic systems and receptors in behavioral phenomena as well as their susceptibility to prolonged EtOH.

Stereotypic wall climbing in mice during ethanol withdrawal: a new measure of physical dependence

A new potentially useful measure for assessing physical dependence in mice chronically exposed to ethanol is described. C3H/He mice continuously exposed to ethanol vapor for four (Experiment 1) or three (Experiment 2) days spent more time engaged in stereotypic climbing behavior than controls. This stereotypic climbing behavior correlated well, both temporally as well as in intensity, with other previously described signs of ethanol withdrawal. All measures of withdrawal behavior (including climbing) peaked at eight hours after withdrawal and returned to control levels by 30-33 hours. The utility of this behavioral assay for assessing physical dependence on ethanol is further discussed with reference to possible underlying neurochemical events.

The effect of neurotensin, TRH and the delta-opioid receptor antagonist ICI 174864 on alcohol-induced narcosis in rats

The effects of microinjections of thyrotropin-releasing hormone (TRH), neurotensin and ICI 174864 into the nucleus accumbens, nucleus caudatus, septum and mesencephalic periaqueductal grey were studied on ethanol-induced narcosis in the rat. Levels of narcosis were assessed by alterations in ethanol-induced hypothermia and sleep time. Ethanol produces a 2 degree C fall in body temperature over the first hour which then recovered over the next 2 h. Sedation was produced to the extent that the righting reflex was lost for between 80 and 90 min. In the nucleus caudatus all 3 peptides were ineffective at altering narcosis. In the periaqueductal grey, septum and accumbens, TRH (5 micrograms) and ICI 174864 (1 microgram) microinjections significantly reduced the sleep time by between 50 and 70%. ICI 174864 was approximately 10 times more potent that TRH at reducing the sleep time. In addition, both these peptides significantly accelerated the recovery from the ethanol-induced hypothermia in the periaqueductal grey, septum and accumbens. ICI 174864 prevented the ethanol-induced fall in body temperature. Neurotensin (5 micrograms) significantly increased the sleep time by up to 50% and potentiated the ethanol-induced hypothermia. These results suggest that the administration of TRH or the blockade of delta-opioid receptors, resulting in an inhibition of endogenous enkephalin transmission, may significantly inhibit ethanol narcosis in the rat. Opposing this, the application of neurotensin appears to potentiate ethanol narcosis. These results also indicate that endogenous enkephalin release plays an important role in ethanol narcosis.