Pineal function during ethanol intoxication, dependence, and withdrawal

Morphologic variations in the pineal gland of the albino rat after a chronic alcoholisation process

We studied the effect of alcohol on the pineal gland of 48 male Wistar rats. Animals were divided into control and experimental groups. The experimental group underwent a previous progressive alcoholisation period with ethanol diluted in water at a concentration of 40%. Animals were sacrificed at 3, 6, 9 and 12 months, and the ultrastructure, karyometric indices, and number of synaptic bodies in the pineal gland were analysed. The results showed progressive morphologic alterations in the ethanol-treated animals, which culminated in fatty degeneration of the pineal parenchyma after 6 months. The karyometric indices decreased in both the central and peripheral areas compared with the control group. Moreover, the seasonal rhythmicity observed in the controls disappeared in the experimental groups, whose number of different populations of synaptic bodies (synaptic ribbons and synaptic spherules) considerably lowered with inversion of their normal seasonal rhythm. These results support that chronic alcoholisation leads to fatty degeneration of the pineal parenchyma, and a considerable alteration in nuclear functional rhythms and synaptic bodies.

Moderate alcohol consumption and 24-hour urinary levels of melatonin in postmenopausal women

CONTEXT

Low overnight urinary melatonin metabolite concentrations have been associated with increased risk for breast cancer among postmenopausal women. The Postmenopausal Women's Alcohol Study was a controlled feeding study to test the effects of low to moderate alcohol intake on potential risk factors for breast cancer including serum and urinary levels of hormones and other biomarkers. Previously, we observed significant increases in concentrations of serum estrone sulfate and dehydroepiandrosterone sulfate in participants after consumption of 15 or 30 g (one or two drinks) of alcohol per day.

OBJECTIVE

In the present analysis, we evaluated the relationship of alcohol consumption with 24-h urinary 6-sulfatoxymelatonin (6-SMT) concentration (micrograms per 24 h).

DESIGN AND PARTICIPANTS

Healthy postmenopausal women (n = 51) consumed a controlled diet plus each of three treatments (a nonalcoholic placebo beverage or 15 or 30 g alcohol/d) during three 8-wk periods in random order under conditions of weight maintenance.

MEASURES

6-SMT was measured in 24-h urine samples that were collected at entry into the study (baseline) and at the midpoint (4 wk) and end (8 wk) of each of the three diet periods.

RESULTS

Concentration of 6-SMT was not significantly modified by the alcohol treatment after adjustment for body mass index, hours of sleep, daylight hours, and baseline level of 6-SMT.

CONCLUSIONS

These results suggest that low to moderate daily alcohol consumption does not significantly affect 24-h urinary levels of melatonin among healthy postmenopausal women.

Influence of melatonin or its antagonism on alcohol consumption in ethanol drinking rats: a behavioral and in vivo voltammetric study

Melatonin, an indoleamine hormone synthesized in the pinealocytes, has been implicated as influencing the intake of alcohol in rats. It has been shown that this hormone is voltammetrically electroactive at the surface of pretreated carbon fiber microelectrodes in vitro and in vivo, in rat cerebral melatonergic regions such the pineal gland. The aim of this work consisted in the study of the influence of melatonin on spontaneously ethanol drinking or ethanol avoiding rats selected throughout a free choice two bottle test. It appeared that only the water preferring rats were affected by treatment with the hormone and that in vivo voltammetric related levels of melatonin were higher in the pineal gland of ethanol drinking rats versus water preferring rats. In addition, when treated with the melatonin antagonist GR128107 ethanol drinking rats significantly reduced the spontaneous consumption of alcohol.

Ethanol consumption and pineal melatonin daily profile in rats

It is well known that melatonin participates in the regulation of many important physiological functions such as sleep-wakefulness cycle, motor coordination and neural plasticity, and cognition. However, as there are contradictory results regarding the melatonin production diurnal profile under alcohol consumption, the aim of this paper was to study the phenomenology and mechanisms of the putative modifications on the daily profile of melatonin production in rats submitted to chronic alcohol intake. The present results show that rats receiving 10% ethanol in drinking water for 35 days display an altered daily profile of melatonin production, with a phase delay and a reduction in the nocturnal peak. This can be partially explained by a loss of the daily rhythm and the 25% reduction in tryptophan hydroxylase activity and, mainly, by a phase delay in arylalkylamine N-acetyltransferase gene expression and a 70% reduction in its peak activity. Upstream in the melatonin synthesis pathway, the results showed that noradrenergic signaling is impaired as well, with a decrease in β1 and α1 adrenergic receptors' mRNA contents and in vitro sustained loss of noradrenergic-stimulated melatonin production by glands from alcohol-treated rats. Together, these results confirm the alterations in the daily melatonin profile of alcoholic rats and suggest the possible mechanisms for the observed melatonin synthesis modification.

Tryptophan metabolism in alcoholism

Acute and chronic alcohol (ethanol) intake and subsequent withdrawal exert major effects on tryptophan (Trp) metabolism and disposition in human subjects and experimental animals. In rats, activity of the rate-limiting enzyme of Trp degradation, liver Trp pyrrolase (TP), is enhanced by acute, but inhibited after chronic, ethanol administration, then enhanced during withdrawal. These changes lead to alterations in brain serotonin synthesis and turnover mediated by corresponding changes in circulating Trp availability to the brain. A low brain-serotonin concentration characterizes the alcohol-preferring C57BL/6J mouse strain and many alcohol-preferring rat lines. In this mouse strain, liver TP enhancement causes the serotonin decrease. In man, acute ethanol intake inhibits brain serotonin synthesis by activating liver TP. This may explain alcohol-induced depression, aggression and loss of control in susceptible individuals. Chronic alcohol intake in dependent subjects may be associated with liver TP inhibition and a consequent enhancement of brain serotonin synthesis, whereas subsequent withdrawal may induce the opposite effects. The excitotoxic Trp metabolite quinolinate may play a role in the behavioural disturbances of the alcohol-withdrawal syndrome. Some abstinent alcoholics may have a central serotonin deficiency, which they correct by liver TP inhibition through drinking. Further studies of the Trp and serotonin metabolic status in long-term abstinence in general and in relation to personality characteristics, alcoholism typology and genetic factors in particular may yield important information which should facilitate the development of more effective screening, and preventative and therapeutic strategies in this area of mental health.

A functional polymorphism in the promoter region of the tryptophan hydroxylase gene is associated with alcohol dependence in one aboriginal group in Taiwan

BACKGROUND

Polymorphisms within intron 7 of the tryptophan hydroxylase (TPH1) gene were found to be associated with alcohol dependence in different ethnic groups, including the aboriginal Bunun group in Taiwan. This study aimed to identify genetic variants at the TPH1 locus and to examine their associations with alcoholism. We hypothesized that the polymorphism of TPH1 gene is functional and influences the human circadian rhythm to contribute to the pathophysiology of alcohol dependence.

METHODS

DNA from the Taiwanese Han and Bunun was subjected to sequence for screening genetic variation in the coding and promoter regions of the TPH1 locus. Polymorphisms among individuals with alcohol dependence and control subjects in two ethnic groups in Taiwan were investigated.

RESULTS

Three variants in the TPH1 promoter region were identified, and the markers are in complete linkage disequilibrium in both populations. Positive associations at both allelic and genotypic levels were obtained between case and control groups in the Bunun. Expression studies demonstrated that the variants indeed affected reporter gene activity in human choriocarcinoma and colon adenocarcinoma cell lines.

CONCLUSIONS

Polymorphisms in the promoter region may influence the function of the TPH1 gene and further influence the proclivity of alcohol dependence in one ethnic group in Taiwan. The associations between TPH1 genotypes and alcoholism may deserve further investigation.

Reversal of Reserpine-Induced Orofacial Dyskinesia and Cognitive Dysfunction by Quercetin

Tardive dyskinesia (TD) is a serious neurological syndrome associated with long-term administration of neuroleptics to humans and experimental animals. The pathophysiology of this disabling and commonly irreversible movement disorder is still obscure. It may be caused by a loss of dopaminergic cells or may be due to free radicals as a product of high synaptic dopamine levels. Quercetin is a bioflavonoid with strong antioxidant properties. Repeated treatment with reserpine (1.0 mg/kg) on each other day for a period of 5 days (days 1, 3 and 5) significantly induced vacuous chewing movements (VCMs) and tongue protrusions (TPs) in rats. Chronic treatment with quercetin for a period of 4 weeks to reserpine-treated animals significantly and dose dependently (50 and 100 mg/kg) reduced the reserpine-induced VCMs and TPs. Reserpine-treated animals also showed poor retention of memory in elevated plus-maze task paradigm. Chronic quercetin administration significantly reversed reserpine-induced retention deficits. Biochemical analysis revealed that chronic reserpine treatment significantly induced lipid peroxidation and decreased the glutathione (GSH) levels in the brains of rats. Chronic reserpine-treated rats showed decreased levels of antioxidant defense enzymes, superoxide dismutase (SOD) and catalase. Chronic administration of quercetin dose dependently (50-100 mg/kg) and significantly reduced the lipid peroxidation and restored the decreased GSH levels by chronic reserpine treatment. It also significantly reversed the reserpine-induced decrease in brain SOD and catalase levels in rats. The results of the present study clearly indicated that quercetin has a protective role against reserpine-induced orofacial dyskinesia and memory impairment. Consequently, the use of quercetin as a therapeutic agent for the treatment of TD should be considered.

Disordered sleep, nocturnal cytokines, and immunity: interactions between alcohol dependence and African-American ethnicity

Sleep disturbance is one of the most prominent complaints of alcohol-dependent patients. In view of recent evidence that the immune system is integrated with other homeostatic processes ultimately regulated by the brain, the influence of sleep on host defense mechanisms and the expression of proinflammatory and T helper cell cytokines deserves attention in alcohol dependence. Although not all immune alterations found in alcohol-dependent persons are related to disordered sleep, it is exceedingly important to know whether sleep influences immunity in alcoholism because of the recognized impact of disordered sleep on infectious disease risk. Conversely, feedback systems are also operating between the brain and the immune system, and abnormalities in the expression of cytokines might contribute to sleep disturbances in alcohol-dependent persons. In this review, we identify the immune alterations found in association with alcohol dependence and discuss the implications of these findings for infectious disease risk, with particular attention to the interaction between African-American ethnicity and alcoholism in contributing to this risk. We provide evidence that sleep disruption occurs in association with alcohol dependence and that African-American alcohol-dependent persons show greater abnormalities in sleep and sleep regulatory processes than shown by Euro-American alcohol-dependent persons. The relations among alcoholism, sleep, and immunity are discussed, with an emphasis on understanding how the cytokine network is altered during sleep in the African-American alcohol-dependent populations. The potential is to use cytokine agonists or antagonists to determine whether physiologic changes in cytokines have a role in the homeostatic regulation of sleep in human beings, which has tremendous implications for the development of novel treatments of alcohol-related sleep disorders.

Abnormal nocturnal melatonin secretion and disordered sleep in abstinent alcoholics

BACKGROUND

Alcoholic patients show prominent disturbance of sleep as measured by electroencephalogram, with difficulties in the onset and maintenance of sleep. Given the role of melatonin in the regulation of the sleep-wake cycle, this study examined the relationship between nocturnal expression of melatonin and sleep in alcoholics as compared with control subjects.

METHODS

Alcoholic patients (n = 11) and comparison control subjects (n = 10) underwent all-night polysomnography and serial blood sampling every 30 min from 10:00 PM to 6:30 AM for measurement of circulating levels of melatonin and cortisol.

RESULTS

Coupled with prolonged sleep latency, alcoholics showed lower levels of melatonin during the early part of the night and a delay in the onset of the nocturnal plateau or peak value of melatonin as compared with control subjects. The nocturnal delay of melatonin correlated with prolonged sleep latency. Circulating levels of cortisol were lower during the early part of the night and higher in the late part of night in the alcoholics as compared with the control subjects.

CONCLUSIONS

A delay in the nocturnal rise of melatonin may contribute to disordered sleep in chronic alcoholics, with implications for the use of melatonin in the treatment of insomnia in recovering alcoholics.

Effect of exogenous melatonin on ethanol-induced changes in Na(+),K(+)- and Ca(2+)-ATPase activities in rat synaptosomes

In the present study, the effects of acute ethanol (EtOH) toxicity and of exogenous melatonin (MLT) on this toxicity were examined by measuring membrane-bound ATPases and acetylcholinesterase activities in rat synaptosomal membranes. The concentrations of plasma alpha-tocopherol and adrenal ascorbic acid (AA) were also measured. Synaptosomal Na(+),K(+)-ATPase and Ca(2+)-ATPase activities were significantly depressed in acute EtOH-intoxicated rats compared with controls, while acetylcholinesterase activity remained unaltered. Pretreatment with MLT (10 mg/kg) prior to acute EtOH administration prevented EtOH-induced inhibition of ATPases. Adrenal AA and plasma alpha-tocopherol levels were also depressed regardless of MLT pretreatment. MLT treatment alone affected neither membrane-bound enzyme activities nor tissue and blood levels of vitamins C and E. It is concluded that acute EtOH intoxication disturbs neural transport functions through the membrane-bound ATPase activity depression. Reduced AA and alpha-tocopherol levels may contribute to the neurodegenerative effects of EtOH. However, pretreatment with a high dose of MLT before EtOH administration may be beneficial to prevent EtOH-induced toxicity on ATPase-mediated neural transport functions.

[Alcohol, chronobiology and sleep]

Chronobiology is the scientific discipline of biologic rhythm study. Applications of the emerging concepts of chronobiology are now use in several fields of clinical medicine. Alcohol related disorders seems to be clarified with the main concepts of chronobiology. Thus chronopharmacology (specially chronokinetics and time-related differences in drug effects) clears up variations of blood alcohol levels and toxicity of ethanol during the 24 h, chronesthesy explains the action of ethanol on biological rhythms of hormone secretions and sleep, and the concept of chronopathology seems to be apply to alcohol dependence. We review in this article some applications in alcohol related disorders of the main concepts of chronobiology.

The effects of acute melatonin and ethanol treatment on antioxidant enzyme activities in rat testes

The pineal hormone melatonin (N -acetyl, 5-methoxytryptamine) was recently accepted to act as an antioxidant under both in vivo and in vitro conditions. In this study, we examined the possible preventive effect of melatonin on ethanol-induced lipid peroxidation in rat testes. Thirty-seven male Wistar albino rats, 5.5--6 months old, were randomly divided into four groups (9--10 animals in each). The first group (control animals) received 4% ethanol at similar intervals to the experimental groups to equalize the stress effect. The second group received only melatonin i.p. 7 mg kg(-1)bw three times over 1.5 h intervals. The third group received only 30% alcohol 3 g kg(-1)bw twice daily. The fourth group were treated with melatonin and ethanol according to the above protocol, melatonin injections preceding ethanol treatments. The product of lipid peroxidation, malondialdehyde (MDA) and antioxidant enzymes, superoxide dismutase (Cu--Zn SOD), glutathione peroxidase (GPx) and catalase (CAT) were measured in the post-mitochondrial fraction of the testes. MDA levels were significantly increased due to acute ethanol intoxication. GPx activity was higher in the three experimental groups than the control levels. The activity of CAT was increased significantly in the melatonin plus ethanol-treated group but the other groups appeared not to be influenced by acute ethanol treatment. Cu--Zn SOD activity remained unaltered. These results suggest that antioxidants may be a protective agent for the testicular injury caused by ethanol consumption.

Possible antioxidant mechanism in melatonin reversal of aging and chronic ethanol-induced amnesia in plus-maze and passive avoidance memory tasks

Cognitive dysfunction is one of the most striking age-related impairments seen in human beings and animals. This impairment probably is due to the vulnerability of the brain cells to increased oxidative stress during aging process. Pineal hormone melatonin is reported to be an endogenous antioxidant, whose peak plasma level declines during aging and in Alzheimer's disease (AD). Present experiments were performed to study the possible effect of exogenously administered melatonin on cognitive performance of young, aged, or ethanol-intoxicated mice (an animal model for AD) using one trial step-down type of passive avoidance and elevated plus-maze task. Aged or chronic ethanol-treated mice showed poor retention of memory in step-down passive avoidance and in elevated plus-maze task. Chronic administration of melatonin (0.1-10 mg/kg, sc) for 30 d or its coadministration with ethanol (15% W/V, 2 g/kg perorally) for 24 d significantly reversed the age-induced or chronic ethanol-induced retention deficits in both the test paradigms. However, in both the memory paradigms chronic administration of melatonin failed to modulate the retention performance of young mice. Chronic administration of melatonin (0.1-10 mg/kg) for 30 d also reversed age-associated decline in forebrain total glutathione (tGSH) level. Chronic ethanol administration to young mice produced decline in forebrain tGSH level and enhanced brain lipid peroxidation, which was significantly reversed by coadministration of melatonin (10 mg/kg). The results of this study showed chronic melatonin treatment reverses cognitive deficits in aged and ethanol-intoxicated mice, which is associated with its antioxidant property.

Alcohol consumption and urinary concentration of 6-sulfatoxymelatonin in healthy women

Consumption of alcoholic beverages may suppress circulating melatonin levels at night, possibly resulting in an increase in circulating estrogen. An increased estrogen burden could increase the risk of breast cancer. This study was designed to investigate whether alcohol consumption is associated with a decrease in nighttime melatonin levels in a group of healthy women. A total of 203 randomly selected healthy women between the ages of 20 and 74 years were recruited for a broader study of the effects of exposure to power-frequency magnetic fields on nocturnal levels of urinary 6-sulfatoxymelatonin. For the purposes of this analysis, data collection consisted of the following during two seasons of the year: (1) an in-person interview, (2) a daily activity diary, and (3) nocturnal urine collection for each of 3 consecutive nights. We found that the nocturnal urinary concentration of the primary metabolite of melatonin (6-sulfatoxymelatonin) decreased in a dose-dependent manner with increasing consumption of alcoholic beverages in the preceding 24-hour period, after taking into account the independent effects on melatonin of age, hours of darkness, use of medications that affect melatonin levels, and body mass index. A categorical analysis revealed no effect of one drink, but a 9% reduction with two drinks, a 15% reduction with three drinks, and a 17% reduction with four or more drinks. It remains unknown whether such a change could affect estrogen levels or breast cancer risk.

Disrupted melatonin-secretion during alcohol withdrawal

1. The synthesis of the pineal hormone, melatonin, is under adrenergic control. The brain's rhythm generating system (suprachiasmatic nucleus and associated systems) which is synchronised by the light-dark cycle controls norepinephrine release from the sympathetic nerve terminal resulting in cAMP accumulation. Increased cAMP leads to induction of the rate-limiting enzyme, N-acetyltransferase and synthesis of melatonin. The pineal exhibits a circadian rhythm with highest blood levels of the hormone being present during the night. The circadian rhythm of melatonin production provides important time-of-day and time-of-year information and, as a result, this hormonal cycle drives other 24-hour rhythms as well as seasonal cycles of reproduction, at least in photoperiodic mammals. 2. Chronic alcoholics were withdrawn from alcohol during a continued period of 4 days and nights. Blood samples were drawn from an indwelling venous catheter and sleep was monitored with polysomnography. No medication was used. No alcohol intake was allowed after admission. Bright light treatment was applied during day 3 of the study. 3. During the 4 days of alcohol-withdrawal the night time melatonin-secretion was disrupted. More than 50% of the patients had a very low secretion (< 30 pg/ml) which did not normalize during the study period. Psychopathology, sleep quality and sleep architecture improved significantly. The melatonin secretion pattern showed low values throughout the study. This low melatonin secretion might reflect the long lasting toxic influence of alcohol on the biological clock and/or a direct inhibitory effect on pineal function. These are different effects, although interrelated. 4. Ethanol has a direct inhibitory effect on pineal melatonin synthesis. A well-recognized action of ethanol is its ability to permeate and perturb the structure of cell membranes and may be related to its lipophilic properties. The changes in membrane fluidity seem to last longer than the study period of 4 days.

Impaired melatonin secretion in patients with Wernicke-Korsakoff syndrome

OBJECTIVES

Melatonin (MT) undergoes circadian changes in response to external light conditions and has been implicated in the control of other circadian hormone variations. Alcohol inhibits MT secretion in healthy subjects. The purpose of the present investigation was to elucidate whether patients with Wernicke-Korsakoff syndrome (WKS) also have impaired MT secretion after a period of prolonged alcohol abstention. If so, it would be of interest to find out whether this affects cortisol rhythmicity.

DESIGN

Seven patients with WKS and 8 healthy controls were included in the study. Venous blood was sampled every 2nd h between 18.00 and 08.00 hours, and urine collected between 22.00 and 07.00 hours.

SETTING

Department of Internal Medicine, Endocrinology Section, Södersjukhuset, Stockholm.

MAIN OUTCOME MEASURES

Peak serum MT values during the night, total nocturnal MT secretion (estimated by MT incremental areas), and urinary excretion of MT were determined in each participant. Serum cortisol levels were determined in the patients at 18.00, 02.00 and 08.00 hours.

RESULTS

Patients with WKS had a markedly reduced nocturnal secretion of MT compared to healthy volunteers (MT incremental areas 0.33 +/- 0.21 vs. 1.60 +/- 0.29 nmol L-1 h-1, mean +/- SEM; P < 0.005). Amongst the patients, the serum cortisol level was higher in the morning than in the afternoon (331 +/- 46 vs. 240 +/- 52 nmol L-1; P < 0.01), and showed a nadir during the night (138 +/- 45 nmol L-1) as in normal individuals.

CONCLUSION

Patients with WKS have markedly reduced nocturnal secretion of MT. The exact mechanism behind this finding has to be further elucidated. However, it is of interest to note that despite the lack of clearcut circadian MT changes. WKS patients retain normal cortisol secretion, thus suggesting that MT rhythm may not be obligatory for the proper control of circadian cortisol rhythmicity.

Inhibition of melatonin secretion by ethanol in man

To determine whether ethanol inhibits nocturnal melatonin (MT) secretion, three experiments (A, B, and C) were performed in seven normal subjects. In A, ethanol at a dose of 0.34 g/kg was administered orally at 6:00, 8:00, and 10:00 PM. Each dose was increased to 0.52 g/kg in B. In C, water was substituted for ethanol. Blood samples for determination of serum MT levels were drawn every second hour between 6:00 PM and 8:00 AM. Urinary excretion of MT during the night was also determined. In A, serum ethanol reached a maximal level of 13 +/- 1 mmol/L at 12 midnight. In B, the corresponding maximum was 25 +/- 1 mmol/L. The higher alcohol dose inhibited nocturnal MT secretion by 20% +/- 5% (P < .01), whereas the lower dose lacked such effect. Urinary excretion of MT was left unaffected by alcohol at both doses. Five additional normal subjects were given alcohol as described above at a dose of 0.52 g/kg (experiment D). This induced mild nocturnal hypoglycemia as evidenced by a glucose decremental area (5.9 +/- 1.8 mmol/L.h) that differed significantly from zero (P < .05). To determine whether a reduced glucose delivery to pinealocytes might contribute to the decreased MT secretion in alcohol-intoxicated subjects, two experiments (E and F) were performed in eight healthy individuals. In E, ethanol was given orally as in B; three small oral doses of glucose were also given at 8:00 PM, 10:00 PM, and 12 midnight. In F, water was substituted for ethanol and glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chronic ethanol administration on the rat pineal N-acetyltransferase and thyroxine type II 5'-deiodinase activities

Chronic ethanol intake resulted in a significant decrease in the rate of ponderal growth and an impaired nyctohemeral profile of pineal N-acetyltransferase (NAT) activity. In ethanol-treated animals, the onset of the nocturnal NAT increase is delayed by 2 hours when compared to control animals. Moreover, pineal NAT nocturnal peak was reached at 4 h (2 hours later than controls), while pineal type II thyroxine 5'-deiodinase (5'-D) nyctohemeral profile was not modified by ethanol administration. The effect of ethanol administration (12 weeks) on 5'-D activity in different tissues was also studied. Ethanol induced a 5'-D activity increase in hypothesis and brain frontal cortex, when compared to control animals. No change in 5'-D activity is observed in either pineal gland, Harderian gland, or brown adipose tissue. Since basal values of 5'-D activity in hypophysis or brain frontal cortex are particularly dependent on serum thyroxine (T4) concentration, the effect of chronic ethanol administration on thyroid hormone levels was studied. Serum T4 levels in ethanol-treated animals were significantly decreased when compared to controls at any time point studied. However, no change in serum 3',3,5-triiodothyronine (T3) levels were found.

Ethanol reduces norepinephrine-stimulated melatonin synthesis in rat pinealocytes

In this study, the in vitro effects of ethanol on norepinephrine-stimulated cyclic AMP (cAMP), N-acetyltransferase (NAT), and melatonin (MT) production were examined in dispersed rat pinealocytes. Cellular cAMP content was determined 15 min after treatment; whereas NAT activity and MT release in the medium were determined 4.5 h after treatment. It was found that ethanol less than or equal to 200 mM had no effect on norepinephrine-stimulated cAMP response, whereas 25 mM ethanol resulted in a significant inhibition of norepinephrine-stimulated NAT and MT levels. Furthermore, ethanol was equally effective in inhibiting the dibutyryl cAMP-stimulated NAT and MT levels. The inhibitory action of ethanol was not due to a direct effect or a delay in the onset of NAT activity. When alcohols with different chain lengths were used, it was found that their inhibitory potencies were related to their chain lengths with butanol greater than propanol greater than ethanol greater than methanol. Taken together, these findings indicate that (1) ethanol has an inhibitory action on norepinephrine-stimulated MT synthesis, (2) one site of ethanol action is distal to cAMP elevation, and (3) the inhibitory effect of ethanol on pineal MT synthesis appears to be secondary to its hydrophobic action.

Urine melatonin in alcoholic patients: a marker of alcohol abuse?

Ethanol is known to alter central neurotransmission and endocrine functions. Urine melatonin was studied in 10 male chronic alcoholic patients, before and after two weeks of controlled alcohol abstinence, and in sex and age matched healthy controls. In both groups, 24-hour urines were collected in two fractions corresponding to day- (D) (08:00-20:00) and night- (N) (20:00-08:00) time. Urine melatonin was assayed by RIA after methylene chloride extraction. Twenty-four hour urine melatonin levels were calculated adding up D and N values. In patients during alcohol intake, the 24-hour urine melatonin levels were significantly higher than in controls (p = 0.004, Student's t test). A disruption of the physiological ratio between N and D values was also observed, since the higher melatonin levels occurred in the D fraction. In drinking alcoholics, melatonin D values were significantly higher than the D values found in controls (p less than 0.01, Student's t test) and in the same patients after alcohol withdrawal (p less than 0.05). The N/D ratio approximated 1 during alcohol intake and became larger than 1 after alcohol withdrawal, as in the controls. The melatonin data were correlated with the suppressive effects of dexamethasone (DXT) on cortisol secretion evaluated both during alcohol intake and during abstinence. After alcohol withdrawal, the two (out of 10) patients, who remained unresponsive to the DXT suppression test, showed high D melatonin values and a low N/D ratio. These preliminary data indicate that in chronic alcoholism the pattern of urinary "melatonin- like immunoreactivity" is altered.

Alcohol consumption and breast cancer

Epidemiologic studies of the relationship of alcohol consumption and breast cancer are generally in support of a direct association, although they are not entirely consistent. Studies supporting this finding have come from many countries around the world and from many investigators working with different study designs and types of populations. Ten of 16 case-control studies, and five of six cohort studies have produced results supporting a positive association. When evaluated together through techniques such as meta-analysis, these studies suggest that there is a 50% increase in breast cancer risk for women who average between one and two drinks per day. All types of alcoholic beverages seem to increase the risk, but there is little agreement between studies on dose-response relationships. No biologic explanation for alcohol's possible role in breast carcinogenesis is yet known, but several hypotheses have been advanced. In the absence of any effective method of primary breast cancer prevention, and because current risk factors explain so little of the incidence of this common cancer, alcohol consumption is of potential importance from both public health and etiologic perspectives. The possible protective effect of moderate alcohol consumption on heart disease should be considered when assessing the risks of this level of consumption on breast cancer.

Neuroendocrine mediated effects of electromagnetic-field exposure: possible role of the pineal gland

Reports from recent epidemiological studies have suggested a possible association between extremely low frequency (ELF; including 50- or 60-Hz) electric- and magnetic-field exposure, and increased risk of certain cancers, depression, and miscarriage. ELF field-induced pineal gland dysfunction is a possible etiological factor in these effects. Work in our laboratory and elsewhere has shown that ELF electromagnetic-field exposure can alter the normal circadian rhythm of melatonin synthesis and release in the pineal gland. Consequences of reduced or inappropriately timed melatonin release on the endocrine, neuronal, and immune systems are discussed. Laboratory data linking ELF field exposure to changes in pineal circadian rhythms in both animals and humans are reviewed. The authors suggest that the pineal gland, in addition to being a convenient locus for measuring dyschronogenic effects of ELF field exposure, may play a central role in biological response to these fields via alterations in the melatonin signal.

Effects of acute ethanol administration on nocturnal pineal serotonin N-acetyltransferase activity

The effect of acute ethanol administration on pineal serotonin N-acetyltransferase (NAT) activity, norepinephrine and indoleamine content was examined in male rats. When ethanol was administered in two equal doses (2 g/kg body weight) over a 4 hour period during the light phase, the nocturnal rise in NAT activity was delayed by seven hours. The nocturnal pineal norepinephrine content was not altered by ethanol except for a delay in the reduction of NE with the onset of the following light phase. Although ethanol treatment led to a significant reduction in nocturnal levels of pineal serotonin content, there was no significant effect upon pineal content of 5-hydroxyindoleacetic acid (5-HIAA). The data indicate that ethanol delays the onset of the rise of nocturnal pineal NAT activity.