Neuroendocrine, fluid balance, and thirst responses to alcohol in alcoholics

Understanding How Acute Alcohol Impacts Neural Encoding in the Rodent Brain

Alcohol impacts neural circuitry throughout the brain and has wide-ranging effects on the biophysical properties of neurons in these circuits. Articulating how these wide-ranging effects might eventually result in altered computational properties has the potential to provide a tractable working model of how alcohol alters neural encoding. This chapter reviews what is currently known about how acute alcohol influences neural activity in cortical, hippocampal, and dopaminergic circuits as these have been the primary focus of understanding how alcohol alters neural computation. While other neural systems have been the focus of exhaustive work on this topic, these brain regions are the ones where in vivo neural recordings are available, thus optimally suited to make the link between changes in neural activity and behavior. Rodent models have been key in developing an understanding of how alcohol impacts the function of these circuits, and this chapter therefore focuses on work from mice and rats. While progress has been made, it is critical to understand the challenges and caveats associated with experimental procedures, especially when performed in vivo, which are designed to answer this question and if/how to translate these data to humans. The hypothesis is discussed that alcohol impairs the ability of neural circuits to acquire states of neural activity that are transiently elevated and characterized by increased complexity. It is hypothesized that these changes are distinct from the traditional view of alcohol being a depressant of neural activity in the forebrain.

Role of aldosterone and mineralocorticoid receptor (MR) in addiction: A scoping review

Preclinical and human studies suggest a role of aldosterone and mineralocorticoid receptor (MR) in addiction. This scoping review aimed to summarize (1) the relationship between alcohol and other substance use disorders (ASUDs) and dysfunctions of the aldosterone and MR, and (2) how pharmacological manipulations of MR may affect ASUD-related outcomes. Our search in four databases (MEDLINE, Embase, Web of Science, and Cochrane Library) indicated that most studies focused on the relationship between aldosterone, MR, and alcohol (n = 30), with the rest focused on opioids (n = 5), nicotine (n = 9), and other addictive substances (n = 9). Despite some inconsistencies, the overall results suggest peripheral and central dysregulations of aldosterone and MR in several species and that these dysregulations depended on the pattern of drug exposure and genetic factors. We conclude that MR antagonism may be a promising target in ASUD, yet future studies are warranted.

Substances of abuse and the blood brain barrier: Interactions with physical exercise

Substance use disorders pose a common medical, social and financial problem. Among the pathomechanisms of substance use disorders, the disruption and increased permeability of the blood-brain barrier has been recently revealed. Physical exercise appears to be a relatively inexpensive and feasible way to implement behavioral therapy counteracting the blood-brain barrier impairment. Concomitantly, there are also studies supporting a potential protective role of selected substances of abuse in maintaining the blood-brain barrier integrity. In this review, we aim to provide a summary on the modulatory influence of physical exercise, a non-pharmacological intervention, on the blood-brain barrier alterations caused by substances of abuse. Further studies are needed to understand the precise mechanisms that underlie various effects of physical exercise in substance use disorders.

Vasopressin and alcohol: a multifaceted relationship

BACKGROUND

Arginine vasopressin (VP) has been implicated in a number of neuropsychiatric disorders with an emphasis on situations where stress increased the severity of the disorder. Based on this hypothesized role for VP in neuropsychiatric disorders, much research is currently being undertaken in humans and animals to test VP as a target for treatment of a number of these disorders including alcohol abuse.

OBJECTIVES

To provide a summary of the literature regarding the role of VP in alcohol- and stress-related behaviors including the use of drugs that target VP in clinical trials.

RESULTS

Changes in various components of the VP system occur with alcohol and stress. Manipulating VP or its receptors can alter alcohol- and stress-related behaviors including tolerance to alcohol, alcohol drinking, and anxiety-like behavior. Finally, the hypothalamic-pituitary-adrenal axis response to alcohol is also altered by manipulating the VP system. However, clinical trials of VP antagonists have had mixed results.

CONCLUSIONS

A review of VP's involvement in alcohol's actions demonstrates that there is much to be learned about brain regions involved in VP-mediated effects on behavior. Thus, future work should focus on elucidating relevant brain regions. By using previous knowledge of the actions of VP and determining the brain regions and/or systems involved in its different behavioral effects, it may be possible to identify a specific receptor subtype target, drug treatment combination, or specific clinical contexts that may point toward a more successful treatment.

Thirst sensation and oral dryness following alcohol intake

Substantial acute and chronic intakes of alcohol or ethanol (EtOH) severely influence oral sensations, such as thirst and oral dryness (dry mouth, xerostomia). Thirst sensation and oral dryness are primarily caused by the activation of neurons in brain regions, including the circumventricular organs and hypothalamus, which are referred to as the dipsogenic center, and by a decrease in salivary secretion, respectively. The sensation of thirst experienced after heavy-alcohol drinking is widely regarded as a consequence of EtOH-induced diuresis; however, EtOH in high doses induces anti-diuresis. Recently, it has been proposed that the ethanol metabolite acetaldehyde induces thirst via two distinct processes in the central nervous system from EtOH-induced diuresis, based on the results of animal experiments. The present review describes new insights regarding the induction mechanism of thirst sensation and oral dryness after drinking alcohol.

Relevance of hemolysis-induced tissue factor expression on monocytes in soft clot formation in alcohol-containing blood

The fluidity of cadaveric blood is an important characteristic in the post-mortem examination of cases of asphyxial death. Although it is empirically known that soft blood clots are present in cadaveric blood containing alcohol, the relationship between such clots and blood alcohol is unclear. We addressed this issue through in vitro studies using blood collected from healthy volunteers. Assessment of global hemostasis by rotational thromboelastometry revealed that ethanol treatment enhanced the procoagulant activity of whole blood. However, ethanol inhibited epinephrine-induced platelet aggregation, whereas plasma levels of von Willebrand factor and the activity of coagulation factors VIII and IX were unaffected. In contrast, tissue factor (TF) activity was higher in plasma obtained from ethanol-treated whole blood than that in plasma from untreated blood. Ethanol induced hemolysis of red blood cells, and the consequent hemoglobin (Hb) release promoted de novo synthesis of TF in isolated monocytes, as determined by real-time reverse transcription PCR, western blotting, and flow cytometry. However, ethanol itself did not induce TF expression in monocytes. Given that TF activates the extrinsic coagulation pathway and amplifies hemostatic reactions, Hb-induced TF expression in monocytes might contribute to soft blood clot formation.

Magnocellular hypothalamic system and its interaction with the hypothalamo-pituitary-adrenal axis

The hypothalamo-neurohypophyseal system plays a key role in maintaining homeostasis and in regulation of numerous adaptive reactions, e.g., endocrine stress response. Nonapeptides vasopressin and oxytocin are the major hormones of this system. They are synthesized by magnocellular neurons of the paraventricular and supraoptic hypothalamic nuclei. Magnocellular vasopressin is known to be one of the main physiological regulators of water-electrolyte balance. Its importance for control of the hypothalamo-pituitary-adrenal axis has been widely described. Magnocellular oxytocin is secreted predominantly during lactation and parturition. The complex actions of oxytocin within the brain include control of reproductive behavior and its involvement in central stress response to different stimuli. It's neuroendocrine basis is activation of the hypothalamo-pituitary-adrenal axis: corticotropin-releasing hormone is synthesized in parvocellular neurons of the paraventricular hypothalamic nuclei. The transitory coexpression of vasopressin in these cells upon stress has been described. Glucocorticoids, the end products of the hypothalamo-pituitary-adrenal axis have both central and peripheral actions. Their availability to target tissues is mainly dependent on systemic levels of corticosteroid-binding globulin. Intrinsic expression of this protein in different brain regions in neurons and glial cells has been recently demonstrated. Regulation of the hypothalamo-pituitary-adrenal axis and hypothalamo-neurohypophyseal system is highly complex. The role of both systems in the pathogenesis of various chronic ailments in humans has extensively been studied. Their disturbed functioning seems to be linked to various psychiatric, autoimmune and cardiovascular pathologies.

Alcohol abuse: critical pathophysiological processes and contribution to disease burden

Alcohol abuse; the most common and costly form of drug abuse, is a major contributing factor to many disease categories. The alcohol-attributable disease burden is closely related to the average volume of alcohol consumption, with dose-dependent relationships between amount and duration of alcohol consumption and the incidence of diabetes mellitus, hypertension, cardiovascular disease, stroke, and pneumonia. The frequent occurrence of alcohol use disorders in the adult population and the significant and widespread detrimental organ system effects highlight the importance of recognizing and further investigating the pathophysiological mechanisms underlying alcohol-induced tissue and organ injury.

Time-course of neuroendocrine changes and its correlation with hypertension induced by ethanol consumption

Ethanol (ETOH) consumption has been associated with endocrine and autonomic changes, including the development of hypertension. However, the sequence of pathophysiological events underlying the emergence of this effect is poorly understood.

AIMS

This study aimed to establish a time-course correlation between neuroendocrine and cardiovascular changes contributing to the development of hypertension following ETOH consumption.

METHODS

Male adult Wistar rats were subjected to the intake of increasing ETOH concentrations in their drinking water (first week: 5%, second week: 10%, third and fourth weeks: 20% v/v).

RESULTS

ETOH consumption decreased plasma and urinary volumes, as well as body weight and fluid intake. Furthermore, plasma osmolality, plasma sodium and urinary osmolality were elevated in the ETOH-treated rats. ETOH intake also induced a progressive increase in the mean arterial pressure (MAP), without affecting heart rate. Initially, this increase in MAP was correlated with increased plasma concentrations of adrenaline and noradrenaline. After the second week of ETOH treatment, plasma catecholamines returned to basal levels, and incremental increases were observed in plasma concentrations of vasopressin (AVP) and angiotensin II (ANG II). Conversely, plasma oxytocin, atrial natriuretic peptide, prolactin and the hypothalamus-pituitary-adrenal axis components were not significantly altered by ETOH.

CONCLUSIONS

Taken together, these results suggest that increased sympathetic activity may contribute to the early increase in MAP observed in ETOH-treated rats. However, the maintenance of this effect may be predominantly regulated by the long-term increase in the secretion of other circulating factors, such as AVP and ANG II, the secretion of both hormones being stimulated by the ETOH-induced dehydration.

Deletion of angiotensin II type 1 receptor gene attenuates chronic alcohol-induced retinal ganglion cell death with preservation of VEGF expression

PURPOSE

To investigate how chronic alcohol consumption affects adult visual nervous system and whether renin-angiotensin system (RAS) is involved in this pathogenic process.

METHODS

Male transgenic mice with angiotensin II (Ang II) type 1 (AT1) receptor gene knockout (AT1-KO) and age-matched wild-type (WT) mice were pair-fed a modified Lieber-DeCarli alcohol or isocaloric maltose dextrin control liquid diet for 2 months. At the end of the study, retinas were harvested and subjected to histopathological and immunohistochemical examination.

RESULTS

We found that chronic alcohol consumption significantly increased retinal ganglion cell (RGC) apoptosis in the retina of WT mice, but not AT1-KO mice, detected by terminal deoxynucleotidyl-transferase-mediated dUTP-nick-end labeling staining and caspase 3 activation, along with an up-regulation of AT1 expression in RGC. At the same time, the phosphorylation of P53 in RGCs was significantly increased for both WT and AT1-KO mice exposed to alcohol, which could be significantly, although partially, prevented by AT1 gene deletion. We further examined the expression of vascular endothelial growth factor (VEGF) and CD31, and found that alcohol treatment significantly decreased the expression of VEGF and CD31 in RGCs of WT mice, but not AT1-KO mice.

CONCLUSION

Taken together, our study demonstrates that the induction of RGC apoptosis by chronic alcohol exposure may be related to p53-activation and VEGF depression, all which are partially dependent of AT1 receptor activation.

The role of renin angiotensin system intervention in stage B heart failure

This article outlines the link between the renin angiotensin aldosterone system (RAAS) and various forms of cardiomyopathy, and also reviews the understanding of the effectiveness of RAAS intervention in this phase of ventricular dysfunction. The authors focus their discussion predominantly on patients who have had previous myocardial infarction or those who have left ventricular hypertrophy and also briefly discuss the role of RAAS activation and intervention in patients with alcoholic cardiomyopathy.

Acute ethanol intoxication and the trauma patient: hemodynamic pitfalls

Many trauma patients are acutely intoxicated with alcohol. Animal studies have demonstrated that acute alcohol intoxication inhibits the normal release of epinephrine, norepinephrine, and vasopressin in response to acute hemorrhage. Ethanol also increases nitric oxide release and inhibits antidiuretic hormone secretion. This article studies the effects of alcohol intoxication (measured by blood alcohol level, BAL) on the presentation and resuscitation of trauma patients with blunt hepatic injuries. A retrospective registry and chart review was conducted of all patients who presented with blunt liver injuries at an ACS-verified, level I trauma center. Data collected included admission BAL, systolic blood pressure, hematocrit, International Normalized Ratio (INR), liver injury grade, Injury Severity Score (ISS), intravenous fluid and blood product requirements, base deficit, and mortality. From September 2002 to May 2008, 723 patients were admitted with blunt hepatic injuries. Admission BAL was obtained in 569 patients, with 149 having levels >0.08%. Intoxicated patients were more likely to be hypotensive on admission (p = 0.01) despite a lower liver injury grade and no significant difference in ISS. There was no significant difference in the percent of intoxicated patients requiring blood transfusion. However, when blood was given, intoxicated patients required significantly more units of packed red blood cells (PRBC) than their nonintoxicated counterparts (p = 0.01). Intoxicated patients also required more intravenous fluid during their resuscitation (p = 0.002). Alcohol intoxication may impair the ability of blunt trauma patients to compensate for acute blood loss, making them more likely to be hypotensive on admission and increasing their PRBC and intravenous fluid requirements. All trauma patients should have BAL drawn upon admission and their resuscitation should be performed with an understanding of the physiologic alterations associated with acute alcohol intoxication.

Binge ethanol intake in chronically exposed rat liver decreases LDL-receptor and increases angiotensinogen gene expression

AIM

To investigated the status of low-density lipoprotein (LDL)-receptor and angiotensionogen gene expression in rats treated chronically with ethanol followed by binge administration, a model that mimics the human scenario.

METHODS

Rats were chronically treated with ethanol in liquid diet for 4 wk followed by a single binge mode of ethanol administration (5 mg/kg body weight). Samples were processed 4 h after binge ethanol administration (chronic ethanol binge). Control rats were fed isocaloric diet. In the control for binge, ethanol was replaced by water. Expression of mRNA for angiotensinogen, c-fos and LDL-receptor, and nuclear accumulation of phospho-extracellular regulated kinases (ERK)1/2 and ERK1/2 protein were examined.

RESULTS

Binge ethanol administration in chronically treated rats caused increase in steatosis and necrosis. Chronic ethanol alone had negligible effect on mRNA levels of LDL-receptor, or on the levels of nuclear ERK1/2 and phospho-ERK1/2. But, chronic ethanol followed by binge caused a decrease in LDL-receptor mRNA, and also decreased the levels of ERK1/2 and phospho-ERK1/2 in the nuclear compartment. On the other hand, chronic ethanol-binge increased mRNA expression of angiotensinogen and c-fos.

CONCLUSION

Binge ethanol after chronic exposure, causes transcriptional dysregulation of LDL-receptor and angiotensinogen genes, both cardiovascular risk factors.

Cardiac insulin resistance and microRNA modulators

Cardiac insulin resistance is a metabolic and functional disorder that is often associated with obesity and/or the cardiorenal metabolic syndrome (CRS), and this disorder may be accentuated by chronic alcohol consumption. In conditions of over-nutrition, increased insulin (INS) and angiotensin II (Ang II) activate mammalian target for rapamycin (mTOR)/p70 S6 kinase (S6K1) signaling, whereas chronic alcohol consumption inhibits mTOR/S6K1 activation in cardiac tissue. Although excessive activation of mTOR/S6K1 induces cardiac INS resistance via serine phosphorylation of INS receptor substrates (IRS-1/2), it also renders cardioprotection via increased Ang II receptor 2 (AT2R) upregulation and adaptive hypertrophy. In the INS-resistant and hyperinsulinemic Zucker obese (ZO) rat, a rodent model for CRS, activation of mTOR/S6K1signaling in cardiac tissue is regulated by protective feed-back mechanisms involving mTOR↔AT2R signaling loop and profile changes of microRNA that target S6K1. Such regulation may play a role in attenuating progressive heart failure. Conversely, alcohol-mediated inhibition of mTOR/S6K1, down-regulation of INS receptor and growth-inhibitory mir-200 family, and upregulation of mir-212 that promotes fetal gene program may exacerbate CRS-related cardiomyopathy.

Activation of MEK 1/2 and p42/44 MAPK by angiotensin II in hepatocyte nucleus and their potentiation by ethanol

Hepato-subcellular effect of angiotensin II (Ang II) and ethanol on the p42/44 mitogen-activated protein kinase (MAPK) and MAPK kinase (MEK 1/2) was investigated in the nucleus of rat hepatocytes. Hepatocytes were treated with ethanol (100 mM) for 24h and stimulated with Ang II (100 nM, 5 min). The levels of p42/44 MAPK and MEK 1/2 were monitored in the nuclear fraction using antibodies. Ang II itself caused significant accumulation of phosphorylated p42/44 MAPK (phospho-p42/44 MAPK) in the nucleus without any significant translocation of p42/44 MAPK protein thereby suggesting activation of p42/44 MAPK in the nucleus. Ang II caused marked accumulation of phosphorylated MEK 1/2 (phospho-MEK 1/2) in the nucleus without any significant accumulation of MEK 1/2 protein. Ratio of phospho-MEK 1/2 to MEK 1/2 protein in the nucleus after Ang II treatment was 2.4 times greater than control suggesting phosphorylation of MEK 1/2 inside the nucleus. Ethanol had no effect on the protein level or the activation of p42/44 MAPK in the nucleus. Ethanol treatment potentiated nuclear activation of p42/44 MAPK by Ang II but not translocation of p42/44 MAPK protein. This was accompanied by potentiation of Ang II-stimulated accumulation of phospho-MEK 1/2 in the nucleus by ethanol. MEK 1/2 inhibitor, U-0126 inhibited Ang II response and its potentiation by ethanol. These results suggest that Ang II-mediated accumulation of phospho-p42/44 MAPK in the hepatocyte nucleus involves MEK 1/2-dependent activation and this effect is potentiated by ethanol.

Renin and aldosterone but not the natriuretic peptide correlate with obsessive craving in medium-term abstinent alcohol-dependent patients: a longitudinal study

Both animal and human studies suggest that volume-regulating hormones could play a role in alcohol dependence as well as in alcohol craving. The role of the volume-regulating hormones, renin, aldosterone, and the N-terminal pro B-type natriuretic peptide (NT-proBNP) in alcohol craving was therefore evaluated in the present study. Twenty-five actively drinking alcohol-dependent patients satisfied the inclusion criteria and were enrolled into the study. The volume-regulating hormones, renin, aldosterone, and the NT-proBNP, and craving measurements--Obsessive-Compulsive Drinking Scale (OCDS) and Penn Alcohol Craving Scale (PACS)--were performed at baseline and after 12 weeks. Sixteen patients remained totally abstinent for the entire 12 weeks and were available for the second assessments. At baseline, no correlations between hormones and craving scores were found with either the 25 patients initially enrolled or the 16 abstinent patients. At 12 weeks, a significant increase of renin and a significant decrease of aldosterone were observed. Aldosterone showed a significant direct correlation with the obsessive OCDS subscore (r=0.59, P=.016) and a trend toward a significant direct correlation with the PACS score (r=0.48, P=.057). Renin demonstrated a significant direct correlation with the obsessive OCDS subscore (r=0.51, P=.041) and with the PACS score (r=0.56, P=.025). The NT-proBNP never correlated with craving measurements. In conclusion, the renin-aldosterone axis could play a role in craving in medium-term abstinent patients and thereby leading to the hypothesis that alcohol craving could be influenced by the fluid volume intake.

Increased circulating vasopressin may account for ethanol-induced hypertension in rats

BACKGROUND

Long-term ethanol intake has been reported to evoke both hypertension and increase of systemic vasopressin levels in rats.

METHODS

In this work, we investigated the involvement of systemic vasopressin in the hypertension evoked in rats by long-term ethanol (20% vol/vol) intake for 2 weeks, by systemic treatment with the V1-vasopressin receptor antagonist dTyr(CH2)5(Me)AVP (50 microg/kg). Moreover, plasma arginine-vasopressin (AVP) content was quantified using an AVP radioimmunoassay and the expression of vasopressin mRNA in the supraoptic (SON) and paraventricular (PVN) nuclei was measured using real-time PCR.

RESULTS

Mild hypertension was observed after 2 weeks of ethanol treatment when compared with control animals. Moreover, an increase in both the expression of vasopressin mRNA and the vasopressin blood content was observed in ethanol-treated rats in comparison to the control group. Basal blood pressure levels of ethanol-treated animals were significantly reduced by IV treatment with the V1-vasopressin receptor antagonist dTyr(CH2)5(Me)AVP. However, dTyr(CH2)5(Me)AVP had no effect on the blood pressure of control animals.

CONCLUSIONS

The results indicate that mild hypertension is already observed at an early phase of ethanol consumption in rats. Because the content of circulating vasopressin was increased in ethanol-treated rats and their basal blood pressure returned to control levels after IV treatment with a V1-vasopressin receptor antagonist, it is proposed that increased circulating vasopressin content may mediate the hypertension observed in ethanol-treated rats.

Ethanol inhibition of angiotensin II-stimulated Tyr705 and Ser727 STAT3 phosphorylation in cultured rat hepatocytes: relevance to activation of p42/44 mitogen-activated protein kinase

Angiotensin (Ang) II-stimulated phosphorylation of signal transducer and activator transcription (STAT) 3 in rat hepatocytes and the effects of ethanol on this activation were investigated. Angiotensin II (100 nM) stimulated Tyr705 and Ser727 phosphorylation of STAT3 and formation of sis-inducing factor complexes. In the presence of U-0126 (10microM), a p42/44 mitogen-activated protein kinase (MAPK) kinase inhibitor, Ang II further increased Tyr705 phosphorylation of STAT3 but completely abrogated Ser727 phosphorylation of STAT3. Inhibition of p42/44MAPK also increased STAT3 DNA-binding activity. Pretreatment with ethanol (100mM) for 24h resulted in decrease in Tyr705 phosphorylation of STAT3 by ethanol alone and inhibition of Tyr705 phosphorylation of STAT3 stimulated by Ang II. Although ethanol potentiates Ang II stimulated p42/44 MAPK activation in hepatocytes, ethanol inhibited Ser727 phosphorylation of STAT3 stimulated by Ang II. Angiotensin II-stimulated STAT3-binding activity was not significantly affected by ethanol treatment. These results suggest a negative regulation of Ang II-stimulated STAT3 tyrosine phosphorylation and STAT3-binding activity through p42/44 MAPK activation in hepatocytes. However, ethanol modulation of Ang II-stimulated STAT3 phosphorylation occurs by MAPK independent mechanisms. Ethanol potentiation of MAPK signaling without suppression of STAT3 function may modulate the course of alcoholic liver injury.

Factors associated with renal cortical echogenicity

We studied the causes of renal cortical echogenicity (RCE). Its bilateral average value (AvRCE) and the left renal cortex/spleen echo ratios (RCSplE) were determined among 22 workers exposed to industrial solvents and 19 controls. Men had a higher AvRCE than women (p = 0.006). Current exposure to solvents increased AvRCE (p = 0.024), as did any exposure to aliphatic solvents (p < 0.001). AvRCE had a significant negative correlation with liver transaminases AST, ALT and GGT and with serum triglycerides. RCSplE correlated positively with AST, ALT and GGT, with total serum cholesterol and with diastolic blood pressure. Besides renal structural changes, RCE may be influenced by renal flow effects and the presence of macromolecules in renal vessels and tubular systems. Incidentally-found altered RCE may warrant the workout of occupational exposure history and general medical investigation if no kidney disease is known to exist.

Angiotensin II type 1 receptor blockade prevents alcoholic cardiomyopathy

BACKGROUND

Activation of the renin-angiotensin system (RAS) may contribute to the development of alcoholic cardiomyopathy. We evaluated the effect of angiotensin II (Ang II) type 1 receptor (AT1) blockade on the development of alcoholic cardiomyopathy.

METHODS AND RESULTS

We serially evaluated left ventricular (LV) and cardiomyocyte function and the RAS over 6 months in 3 groups of instrumented dogs. Eight animals received alcohol (once per day orally, providing 33% of total daily caloric intake); 6 received alcohol and irbesartan (5 mg.kg(-1).d(-1) PO); and 8 were controls. Compared with controls, alcohol ingestion caused sustained RAS activation with progressive increases in plasma levels of Ang II, renin activity, LV angiotensin-converting enzyme activity, and LV myocyte Ang II AT(1) receptor expression. The RAS activation was followed by a progressive fall in LV contractility (E(ES), alcohol-fed dogs 3.9+/-0.8 versus control dogs 8.1+/-1.0 mm Hg/mL); reductions in the peak velocity of myocyte shortening (78.9+/-5.1 versus 153.9+/-6.2 microm/s) and relengthening; and decreased peak systolic Ca2+ transient ([Ca2+]iT) and L-type Ca2+ current (I(Ca,L); P<0.05). Irbesartan prevented the alcohol-induced decreases in LV and myocyte contraction, relaxation, peak [Ca2+]iT, and I(Ca,L). With alcohol plus irbesartan, plasma Ang II, cardiac angiotensin-converting enzyme activity, and AT1 remained close to control values.

CONCLUSIONS

Chronic alcohol consumption produces RAS activation followed by progressive cardiac dysfunction. The cardiac dysfunction is prevented by AT1 receptor blockade.

N-methyl-D-aspartate glutamate receptor mediates spontaneous and angiotensin II-stimulated ovine fetal swallowing

BACKGROUND

In adult rats, N-methyl-D-aspartate (NMDA) receptors have been implicated in the central control of body fluid homeostasis, as intracerebroventricular (ICV) injection of NMDA receptor antagonists suppresses stimulated drinking behavior. Fetal swallowing occurs at a significantly higher rate as compared to adult drinking, contributing to amniotic fluid volume regulation and fetal gastrointestinal development. The aim of present study was to determine the role of central NMDA receptors in the modulation of fetal swallowing activity.

METHODS

Eight time-dated pregnant ewes and fetuses were chronically prepared with fetal vascular and ICV catheters, electrocorticogram (ECoG), and esophageal electromyogram electrodes and studied at 130 +/- 1 days' gestation. Following an initial 2-hour baseline period (time 2 h), the NMDA receptor antagonist, dizocipline (1 mg), was injected ICV. At time 4 h, the dose of dizocipline was repeated, together with angiotensin II (AngII, 6.4 microg). Fetal swallowing was monitored for 2 hours after each injection. Four of these fetuses also received an identical control study (on an alternate day) in which dizocipline was replaced with artificial cerebrospinal fluid (aCSF).

RESULTS

ICV dizocipline injection nearly abolished spontaneous fetal swallowing activities (0.6 +/- 0.1 to 0.2 +/- 0.1 swallows/min; P < .001). ICV AngII in the presence of dizocipline did not demonstrate a dipsogenic effect on fetal swallowing (0.1 +/- 0.1; P < .001). In the control study, ICV injection of aCSF did not change fetal swallowing activity (1.0 +/- 0.1 swallows/min), while ICV AngII resulted in a significant increase in fetal swallowing (2.0 +/- 0.1 swallows/min; P < .001).

CONCLUSIONS

This study demonstrates that central NMDA-glutamate receptor-mediated activity contributes to the high rate of spontaneous and AngII-stimulated fetal swallowing. We speculate that reduced NMDA receptor expression within the forebrain dipsogenic neurons may account for observed differences in drinking activities between the fetus/neonate and the adult.

A correlation of catecholamine and vasoactive Peptide release with hemodynamics in patients undergoing resection of arteriovenous malformations

INTRODUCTION

Control of blood pressure can be a problem for intracranial procedures. To investigate the relationship between hemodynamic variables and endogenous vasoactive substances, we studied patients undergoing resection of arteriovenous malformations (AVMs).

METHODS

This was a nonrandomized, prospective study of six patients who had resection of an intracranial AVM and six patients who had clipping of an intracranial aneurysm (ICA) that had not bled. Operative and postoperative blood pressure was controlled with sodium nitroprusside. Heart rate (HR), mean arterial pressure, pulmonary capillary wedge pressure, and cardiac index (CI) were measured after induction of anesthesia; before, during, and after hypotensive anesthesia; immediately postoperatively; and at 12, 24, and 36 hours postoperatively. Blood samples were drawn simultaneously in the AVM group to measure levels of norepinephrine, epinephrine, renin, aldosterone, vasopressin, angiotensin I, and angiotensin II and correlated with significant hemodynamic changes.

RESULTS

HR and CI increased significantly among patients with AVMs compared with patients with ICAs (p<0.001 and p=0.05, respectively). HR was significantly correlated with renin (r=0.60), norepinephrine (r=1.00), and vasopressin (r=0.66). CI was significantly correlated with epinephrine (r=1.00), renin (r=0.77), angiotensin II (r=0.71), and vasopressin (r=0.82). Patients with AVMs had a hyperdynamic state characterized by increases in HR and CI. These increases were accompanied by increased renin, norepinephrine, vasopressin, epinephrine, and angiotensin II serum concentrates.

CONCLUSIONS

There were no significant differences in blood pressure changes between patients who had resection for AVM and those who had clipping of ICA, probably due to the use of sodium nitroprusside in the AVM group. Patients with AVMs had a hyperdynamic state with increases in epinephrine, norepinephrine, angiotensin II, plasma renin activity, and vasopressin. Whether this hyperdynamic state is caused by the resection of the AVM or the use of sodium nitroprusside (SNP) cannot be concluded. Blockage of these mediators preoperatively may help control blood pressure without sodium nitroprusside.

Preserved Vasopressin Response to Osmostimulation Despite Decreased Basal Vasopressin Levels in Long-Term Abstinent Alcoholics

BACKGROUND

Basal arginine vasopressin (AVP) plasma levels in alcoholic patients are persistently decreased over months of controlled alcohol abstinence. As a potential explanation of this phenomenon, a reduction of AVP immunoreactive neurons was described in the hypothalamus of alcohol-dependent humans and rodents. This study was therefore designed to examine whether long-term abstinent alcoholics have a compromised response of AVP to osmostimulation.

METHODS

Fifteen male alcoholics, aged 42 +/- 2 years, were examined (1) over 12 months of strictly controlled abstinence (longitudinal study) and (2) during an osmostimulation test (5% NaCl infusion at 0.06 ml/kg/min over 2 hr) and were compared with 15 healthy male subjects, aged 41 +/- 2 years. AVP and routine laboratory parameters, including electrolytes and osmolality, were measured.

RESULTS

Starting from lower basal concentrations, alcoholics showed increases similar to those of controls in AVP and plasma osmolality after osmostimulation. The first sensation of thirst was announced significantly later by alcoholics than by controls. Twenty-hour-posttest urine volume and sodium excretion were reduced in alcoholics compared with controls.

CONCLUSIONS

Despite their persistently decreased basal AVP plasma levels, long-term abstinent alcoholics have a well preserved AVP response to osmostimulation. This finding indicates a peripheral suppression of AVP levels that is most likely due to a regulatory set-point shift toward hypotonic hyperhydration, rather than to a reduced central capacity of AVP secretion.

Prenatal exposure to ethanol causes partial diabetes insipidus in adult rats

Chronic consumption of ethanol in adult rats and humans leads to reduced AVP-producing neurons, and prenatal ethanol (PE) exposure has been reported to cause changes in the morphology of AVP-producing cells in the suprachiasmatic nucleus of young rats. The present studies further characterize the effects of PE exposure on AVP in the young adult rat, its hypothalamic synthesis, pituitary storage, and osmotically stimulated release. Pregnant rats were fed a liquid diet with 35% of the calories from ethanol or a control liquid diet for days 7-22 of pregnancy. Water consumption and urine excretion rate were measured in the offspring at 60-68 days of age. Subsequently, the offspring were infused with 5% NaCl at 0.05 ml.kg(-1).min(-1) with plasma samples taken before and at three 40-min intervals during infusion for measurement of AVP and osmolality. Urine output and water intake were approximately 20% greater in PE-exposed rats than in rats with no PE exposure, and female rats had a greater water intake than males. The relationship between plasma osmolality and AVP in PE-exposed rats was parallel to, but shifted to the right of, the control rats, indicating an increase in osmotic threshold for AVP release. Pituitary AVP was reduced by 13% and hypothalamic AVP mRNA content was reduced by 35% in PE-exposed rats. Our data suggest that PE exposure can cause a permanent condition of a mild partial central diabetes insipidus.

Effects of ethanol on the changes in renal fluid and electrolyte handling and kidney morphology induced by long-term chloroquine administration to rats

This study investigated the effects of long-term chloroquine and ethanol administration on renal fluid and electrolyte handling and kidney structure. Male Sprague-Dawley rats were orally administered with chloroquine diphosphate (20 microg kg(-1) bw) and/or ethanol (1.6 g kg(-1) bw) every third consecutive day for 4 weeks. Urine volume and total urinary outputs of Na+ and K+ were determined from 24-h samples. For detailed renal studies, rats were subsequently anaesthetised and challenged with a continuous jugular infusion of 0.077 M NaCl at 150 microl min(-1) 24 h after the last treatment. After a 3-h equilibration period, urine flow, Na+ and K+ excretion rates were determined over a 4-h period. Plasma concentrations of AVP and aldosterone were measured in unanaesthetised rats and in anaesthetised rats after hypotonic saline infusion. In separate groups, the rats were anaesthetised with an overdose of ether after 4 weeks of treatment and part of the right kidney was quickly collected and routinely processed for light microscopy. Chloroquine decreased Na+ excretion and increased plasma aldosterone concentrations in anaesthetised rats. Ethanol alone did not alter urinary Na+ outputs or aldosterone levels. Combined chloroquine and ethanol increased renal Na+ excretion, but did not affect plasma aldosterone levels. In unanaesthetised animals all treatments increased aldosterone levels by comparison with control rats. Urinary Na+ excretion was decreased by separate administration of either chloroquine or ethanol, but increased by combined treatment. Microscopic studies showed that concurrent chloroquine and ethanol administration induced extensive damage of the proximal tubule and collecting ducts cells. The results of this study suggest that alcohol consumption and chloroquine administration could result in diminished renal function possibly due to alteration of renally active hormones or kidney morphology.

Intracerebroventricular infusion of angiotensin II increases water and ethanol intake in rats

The influence of prolonged ingestion of ethanol on stimulation of water or ethanol intake by intracerebroventricular infusion of ANG II was evaluated in rats. Animals were maintained for 5-6 mo with either 10% ethanol solution or water as their only source of fluid. In both groups of rats, infusion of ANG II caused a large increase in water intake (7-fold) and a lesser increase in 10% ethanol intake (2-fold). The effect of ANG II on the volume of ethanol solution ingested, however, was inversely related to the concentration of the ethanol solution. As the concentration of ethanol solution was decreased, frequency and duration of drinking bouts increased. The intake of sweetened 10% ethanol solution or commercially produced wine during infusion of ANG II was similar to the intake of 10% ethanol and not related to taste preference. In conclusion, chronic consumption of ethanol solution did not appear to adversely effect ANG II stimulation of water intake. The intake of ethanol solution during infusion of ANG II was inhibited by a direct effect of ingested ethanol and/or by indirect effect from metabolized ethanol.

Another look at: fuel + O2 --> CO2 + H2O. Developing a water-oriented perspective

Water plays many vital roles which must be maintained despite constant threat of water stress from the environment. Mechanisms to maintain these roles over the long-term involve intermediates of many metabolic pathways, such as glycerol, sucrose, free amino acids and their derivatives. In addition to viewing metabolic products as intermediates along energy-related pathways, nutrition researchers and epidemiologists should consider them as determinants of intracellular fluid maintenance. Satiety processes, oxidative-fuel selection, hormonal control, and intracellular-signaling processes can all be interpreted in terms of water-oriented metabolism. Water intake and hydration status can vary considerably, and may be inadequate for a sizeable proportion of Western adults. Due to the metabolic adaptations required to compensate for perpetually inadequate water, chronic sub-optimal water intakes may be highly relevant to chronic disease etiology. Preliminary evidence links water-oriented metabolism to obesity, diabetes, cardiovascular disease, hypertension and cancer. Development of a water-oriented perspective may reveal an important new area of research in human nutrition and epidemiology.

Effects of alcohol on the synthesis and expression of hypothalamic peptides

Studies aimed at analyzing the deleterious effects of excess alcohol in the brain have revealed structural alterations that are often associated with functional and behavioral disturbances. Among the neuronal damage related to prolonged alcohol exposure, alterations in the synthesizing capabilities and levels of expression of neuroactive peptides have been increasingly reported. Actually, such changes frequently represent the sole repercussion of acute and short-term exposure to ethanol. This review gathers the existing data on the effects of ethanol exposure on the synthesis and expression of hypothalamic peptides. Amid those that can act both as neurotransmitters and neurohormones, we allude to vasopressin, corticotropin-releasing hormone, thyrotropin-releasing hormone and pro-opiomelanocortin and related peptides produced by paraventricular, supraoptic and arcuate neurons. With respect to peptides that act exclusively as neurotransmitters, we address the effects of alcohol on vasoactive intestinal polypeptide, gastrin-releasing peptide, somatostatin and vasopressin synthesized by suprachiasmatic neurons. Hypothalamic neurons that produce peptides that act as neurotransmitters are supposed to be modulated primarily by influences exerted by neuronal afferents, whereas those producing peptides that additionally act as neurohormones are also regulated by peripheral stimuli (e.g., plasma levels of circulating hormones, osmotic challenges). These peculiar features endue the hypothalamus with characteristics that are particularly propitious to enlighten the still cryptic mechanisms underlying the ethanol effects on protein synthesis.

Loss of vasopressin-immunoreactive neurons in alcoholics is dose-related and time-dependent

The chronic consumption of alcohol significantly reduces the number of vasopressin-producing neurons in the rat supraoptic nucleus [Maderia et al. (1993) Neourscience 56, 657-672] suggesting this region is particularly vulnerable to alcohol neurotoxicity. As hypothalamic vasopressin producing neurons are necessary for fluid homeostasis, it is important to assess if similar changes occur in humans. We analysed arginine vasopressin-immunoreactive neurons in the magnocellular hypothalamic nuclei of ten chronic alcoholic men (consuming > 80 g of ethanol per day) and four age- and sex-matched controls (consuming < 10g of ethanol per day). Brains were collected at autopsy and fixed in formalin. Serial 50 mu m-thick-sections of the hypothalamus were stained and assessed. The volume of the paraventricular and supraoptic nuclei and number of neurons were estimated using Cavalieri's principle and the optical dissector technique. The volume of these nuclei significantly correlated with the number of neurons and the number of vasopressin-immunoreactive neurons, and these measures significantly correlated with the maximum daily intake of alcohol. There was a loss of neurons at consumption levels greater than 100 g of ethanol per day, principally affecting the supraoptic nucleus although neuron loss also occurred in the paraventricular nucleus in cases with long histories of alcohol consumption. These results indicate that chronic alcohol consumption is toxic to hypothalamic vasopressin-producing neurons in a concentration- and time-dependent manner. As these magnocellular neurons are osmo-receptive, neuronal loss may result in fluid imbalances.

Acetaldehyde inhibits serum aminopeptidases

Aminopeptidase A (APA)- and aminopeptidase M (APM)-like activity were assayed in Moni-Trol ES with L-alpha-aspartyl-beta-naphthylamide and L-alanyl-beta-naphthylamide, respectively. Upon preincubation of the serum with 89.4, 223.5, and 447 mM acetaldehyde at room temperature for 30 min, a reduction in 26.8%, 55.3%, and 75.8% aminopeptidase A activity was observed. Similarly, aminopeptidase M activity was reduced by 26.5% and 53.1% upon preincubation with 223.5 and 447 mM acetaldehyde. Ethanol at 84.9, 212.3, and 427.9 mM did not significantly affect the enzymic activity. Because aminopeptidase A and aminopeptidase M also degrade the pressor substance, angiotensin II, it is suggested that inhibition of aminopeptidase A- and aminopeptidase M-like activity by acetaldehyde, the product of ethanol metabolism, may lead to higher levels of circulating angiotensin II and, consequently, hypertension, in alcoholics. The hydrolysis of lysine-p-nitroanilide, an aminopeptidase B substrate, was also inhibited upon addition of acetaldehyde to Moni-Trol ES serum.

Structural reorganization in the supraoptic nucleus of withdrawn rats following long-term alcohol consumption

We have recently shown in the supraoptic nucleus (SON) of the rat that prolonged ethanol consumption induces cell degeneration and enlargement of the surviving neurons and of their subcellular organelles. We analyzed the SON of withdrawn rats to evaluate whether it displays any evidence of morphological reorganization following abstinence from ethanol, inasmuch as in this condition the ethanol-induced changes in the plasma levels of neurohormones and plasma osmolality are no longer detectable. A group of 18-month-old withdrawn rats was compared with age-matched, pair-fed control and ethanol-treated rats. To differentiate between the effects of withdrawal and the effects of rehydration, a group of 18-month-old rehydrated rats was also included in this study and compared with age-matched, pair-fed control and dehydrated rats. We estimated the volume of SON, and the total number and mean volume of its neurons. The cross-sectional areas of the vasopressinergic and oxytocinergic populations were also evaluated. At the ultrastructural level, we determined the volumes and surface areas of the rough endoplasmic reticulum and Golgi apparatus, and the volumes of neurosecretory granules and nucleoli. In withdrawn animals, the total number of SON neurons was smaller than in controls, although the neuronal volume was greater. The number of SON neurons did not differ between withdrawn and ethanol-treated rats, despite the reduced volume of SON in the former animals. The decrease of SON volume correlated with and was caused by a reduction in the volume of SON neurons and in the size of the organelles involved in neuro-hormone synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of plasma vasopressin in changes of water balance accompanying acute alcohol intoxication

Acute alcohol intoxication causes diuresis presumably resulting from inhibition of vasopressin (also called antidiuretic hormone) release from the posterior pituitary gland. In contrast, in alcoholics during withdrawal from alcohol, vasopressin release is stimulated, resulting in water retention (antidiuresis) and dilutional hyponatremia. The purpose of this study was to evaluate the role of this biphasic response of vasopressin secretion to alcohol in normal persons. We studied eight healthy men who took part in two study sessions: one involving the ingestion of ethanol (1.2 g/kg of body weight) and the other the ingestion of the same volume of fruit juice during 3 hr from 6 to 9 PM. Starting at 6 AM the following morning, subjects were loaded with water (20 ml/kg of body weight within 15 min). During the first 3 hr of the study, ethanol intake increased diuresis, whereas from midnight to 6 AM, a phase of antidiuresis was obtained. Antidiuresis continued during water loading when the retention of water was 44 +/- 6% during the alcohol experiment and 12 +/- 4% during the control session (p < 0.05). During the alcohol-induced diuresis, the plasma arginine vasopressin levels did not differ from the control experiment, but were higher during the phase of antidiuresis from 10 PM to 6 AM (p < 0.05- < 0.01). Also, after water loading at 8 and 9 AM, they were higher in the alcohol study than in the control experiment (p < 0.05). After alcohol ingestion, serum osmolality was higher than the corresponding control values from 8 PM to 2 AM (p < 0.01- < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical predictors of alcohol withdrawal delirium

Up to now, clinical predictors for the course of the alcohol withdrawal syndrome, especially for the occurrence of a delirium, are lacking. Thus, this study was undertaken to examine whether clinical routine investigations at admission before the withdrawal syndrome can reveal factors indicating a higher risk for the development of a delirium. Our results showed that decreased serum electrolyte concentrations (i.e., chloride and potassium), elevated ALT, and gamma-glutamyltransferase serum levels, as well as ataxia and polyneuropathy at the neurological examination, indicate a higher risk for the development of an alcohol withdrawal delirium.

Acute effects of ethanol on ingestive behavior in rats

The effects of acute ethanol administration on the ingestion of NaCl and food were assessed in adult rats subjected to 1-hr drinking and feeding tests 30 min after intraperitoneal administration of ethanol. Ethanol pretreatment did not induce spontaneous NaCl ingestion, but significantly potentiated angiotensin II-stimulated salt appetite, but not water intake, in a dose-dependent manner. Similarly, ethanol pretreatment significantly potentiated neuropeptide Y-stimulated food intake in nonfasted rats, but did not, by itself, cause spontaneous food ingestion. Ethanol pretreatment also significantly blunted pituitary secretion of oxytocin in response to multiple excitatory stimuli. Finally, administration of oxytocin intracerebroventricularly prevented the ethanol-induced potentiation of salt appetite elicited by angiotensin II. In view of our previous findings that central oxytocin secretion inhibits both NaCl and food intake, we propose that ethanol potentiates the ingestion of various solutes in rats, in part, by inhibiting brain-projecting oxytocinergic pathways concurrently with its well-known effects to inhibit pituitary oxytocin secretion.

Stereological study of the ultrastructural changes induced by chronic alcohol consumption and dehydration in the supraoptic nucleus of the rat hypothalamus

We have previously shown that prolonged alcohol ingestion leads to neuronal loss in the supraoptic nucleus of the rat and that the surviving neurons, mainly the vasopressinergic ones, display marked increase in volume. In an attempt to establish correlates for the volumetric alterations we have studied the organelles of supraoptic nucleus neurons in three groups of rats--ethanol-fed, pair-fed, and dehydrated, in all cases treated from 2 to 12 months of age. The volume and surface area of the rough endoplasmic reticulum and Golgi apparatus, and the volume of nucleoli and neurosecretory granules were estimated on the basis of the respective volume and surface densities. The volumes and surface areas of all quantified organelles were increased in both alcohol-fed and dehydrated animals, although the increases were greater in the former group. Changes in the organelles studied are commonly regarded as reliable indicators of the neurosecretory activity of magnocellular neurons. Thus, our results suggest that under conditions of chronic alcohol exposure, the synthesizing activity of the surviving supra-optic neurons is augmented to compensate for the alcohol-induced neuronal loss and/or as a consequence of the alcohol-induced hyperosmolality. Changes in the transport and release of the neurosecretory material cannot, however, be ruled out as an additional cause of neuronal enlargement.

Hormonal derangements in patients with severe alcohol intoxication

Controversial results of fluid and electrolyte derangements in patients with moderate alcohol intoxication have been described. However, no information is available about severe alcohol intoxication. We investigated differences of hormonal disorders between alcohol-habituated and alcohol-naive subjects with severe ethanol intoxication. The hormonal derangements and recommendations on therapy of these patients are discussed. Thirty-three patients [10 alcohol-naive (group A) and 23 alcohol-habituated (group B) subjects] with severe alcohol intoxication (blood ethanol > 200 mg/dl) were selected for the study. Electrolytes and osmolarity of serum and urine, blood ethanol, vasopressin, renin, and aldosterone were determined on admission 2, 4, and 6 hr later. Fluid balance was calculated for each hour. All patients received isotonic saline solution according to urine production. Group A: On admission, serum osmolarity was increased (308 mOsmol/kg). Concomitantly, vasopressin level was elevated on admission (9.12 pg/ml). Increased serum osmolarity was correlated with elevated vasopressin levels (r = 0.8211; p < 0.005). Serum electrolytes, renin, and aldosterone values were within normal ranges. Group B: On admission, vasopressin level was significantly decreased (0.9 pg/ml), despite an elevated serum osmolarity (309 mOsmol/kg). Serum osmolarity remained high despite a sufficient fluid substitution. In addition, vasopressin level remained suppressed over the observation period. Aldosterone level was significantly increased on admission (319 ng/ml). Accordingly, serum sodium was increased from 142 to 148 mM/liter, and serum potassium was decreased from 3.9 to 3.4 mM/liter. Response to hyperosmolarity due to severe alcohol intoxication is different in alcohol-naive and alcohol-habituated subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of chronic alcohol consumption and of dehydration on the supraoptic nucleus of adult male and female rats

Ethanol ingestion affects the hypothalamo-neurohypophysial system resulting in increased diuresis, dehydration and hyperosmolality. We studied the supraoptic nucleus, of the hypothalamus, in ethanol-treated rats, to determine if ethanol alone and/or the associated disturbances of water metabolism lead to structural alterations in a nucleus known to play a central role in fluid homeostasis. Groups of male and female rats were ethanol-treated until 12 and 18 months of age and compared with age-matched pair-fed controls. Twelve and 18-month-old control groups and 12-month-old water control groups (rats submitted to chronic dehydration) were also included in this study in an attempt to differentiate between the effects of undernutrition and dehydration/hyperosmolality, and the specific neurotoxic effects of ethanol. We estimated the volume of the supraoptic nucleus and the numerical density of its neurons and calculated the total number of supraoptic neurons. The volume of both supraoptic neurons and neuropil were also estimated. In immunostained material the ratio of vasopressin to oxytocin neurons and the cross-sectional areas of the two neuronal types were evaluated. There was marked neuronal loss in alcohol-treated rats, but the volume of the supraoptic nucleus was increased. The increase in the volume of the supraoptic nucleus correlated with and was due to increases in the volume was particularly marked for vasopressin neurons. No significant differences were found between controls and pair-fed controls in any of the parameters investigated. In water control rats, the volume of the supraoptic nucleus and of the supraoptic neurons and neuropil was also greater than in pair-fed controls. However, the variations found were not as marked as in ethanol-treated rats and there was no cell loss. These findings reveal, for the first time, that chronic ethanol consumption affects the morphology of supraoptic neurons and neuropil and, consequently, the structure of the entire supraoptic nucleus. Moreover, this study supports the view that ethanol has direct neurotoxic effects on supraoptic neurons because the alterations that occur are not mimicked in animals in which water metabolism alone is disturbed.

Chronic ethanol intake decreases vasopressin mRNA content in the rat hypothalamus: a PCR study

Vasopressin mRNA content was studied by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in the hypothalami of rats chronically treated with ethanol (EtOH). Quantitative RT-PCR allows for the accurate measurement of peptide mRNA levels in discrete regions of the brain of individual animals. EtOH markedly reduced the level of vasopressin mRNA. Furthermore, salt loading was ineffective in inducing a significant increase in vasopressin mRNA level in EtOH-treated rats, unlike in controls. The present results suggest that EtOH not only decreases vasopressin mRNA content in the rat hypothalamus, but also impairs its capacity to respond to salt loading.