Alcohol-induced inhibition of LH secretion in intact and gonadectomized male and female rats: possible mechanisms

Erectile Dysfunction in Alcohol Use Disorder and the change in erectile function after one month of abstinence

OBJECTIVE

The association between alcohol use and erectile dysfunction (ED) has not been explored adequately. The aim of this study is (i) to determine the prevalence of ED in patients with Alcohol use disorder (AUD), (ii) the association of ED with sociodemographic and clinical variables, (iii) the association between severity of drinking and sociodemographic and clinical variables, and (iv) the assess the change in ED after one month of abstinence from alcohol.

METHODS

203 consecutive patients were recruited into the study after taking written informed consent. Sociodemographic data was collected using a proforma and ED was assessed using International Index of Erectile Function-5 (IIEF-5). The patients were also followed up after 1 month of abstinence to assess the change in erectile function.

RESULTS

The prevalence of ED was 68.5%. Out of the 203 subjects, 28.1% had mild ED, 24.1% had mild to moderate ED, 9.9% had moderate ED and 6.4% had severe ED. Significant association were seen between ED and age, marital status, diabetes mellitus, hypertension, total duration, and severity of drinking. A significant association was seen between severity of drinking and age, diabetes mellitus, hypertension, alcoholic liver disease, tobacco use and duration of drinking. The improvement in ED after 1 month abstinence was found to be significant.

CONCLUSIONS

ED is a common problem in patients with AUD. Routine assessment of sexual functioning is warranted in patients with AUD and the information that ED improves with abstinence can provide an impetus to change.

The Impact of Abstinence From Alcohol on Erectile Dysfunction: A Prospective Follow up in Patients With Alcohol Use Disorder

BACKGROUND

There is a compelling evidence for the relation between alcohol use and erectile dysfunction (ED), however the impact of alcohol abstinence on improvement of ED is explored sparsely.

AIM

This study aimed to determine the impact of alcohol abstinence on ED. The association between total duration of drinking, the quantity of alcohol consumed, sociodemographic, clinical variables and ED were also studied.

METHODS

One hundred and four subjects with alcohol use disorder and complaints of ED meeting the inclusion and exclusion criteria were recruited into the study after taking written informed consent. The subjects were assessed at baseline and after 3 months of abstinence from alcohol with IIEF-5 and a specially designed pro forma. Wilcoxon signed rank test was used to assess the change in ED after 3 months of abstinence. Chi square test was done to assess the associations and binary logistic regression was done to determine the significance of variables after 3 months of abstinence.

OUTCOMES

Improvement in ED after 3 months of abstinence from alcohol and its association between socio demographic and clinical variables were assessed.

RESULTS

Of the 104 subjects studied, 88.5% (92) showed improvement in ED after 3 months of abstinence from alcohol. Wilcoxon signed rank test showed that the improvement in ED after 3 months of abstinence was significant. (Z = 8.708, P < .001). Significant association was found between age, alcoholic liver disease, total duration of drinking, and number of standard drinks per day with ED after 3 months of abstinence.

CLINICAL IMPLICATIONS

Information that ED will improve with abstinence from alcohol can be used in deaddiction treatment to provide a motivation for change.

STRENGTH AND LIMITATIONS

This study aims to fill the gap in literature as only a few studies have examined the impact of abstinence from alcohol on ED. The main limitations of this study are short follow up period and since this study was conducted in a tertiary care hospital it could have given rise to Berksonian bias.

CONCLUSION

Results indicate that ED shows improvement with abstinence from alcohol. Absence of alcoholic liver disease, younger age, shorter duration of drinking, lesser number of standard drinks per day had a significant influence in the improvement of ED with alcohol abstinence and this information can be beneficial in treatment to provide an impetus for change. Karunakaran A., Michael J. P. The Impact of Abstinence From Alcohol on Erectile Dysfunction: A Prospective Follow up in Patients With Alcohol Use Disorder. J Sex Med 2022;19:581-589.

Acute Ethanol Exposure Enhances Synaptic Plasticity in the Dorsal Striatum in Adult Male and Female Rats

Background:

Acute (ex vivo) and chronic (in vivo) alcohol exposure induces neuroplastic changes in the dorsal striatum, a critical region implicated in instrumental learning.

Objective:

Sex differences are evident in alcohol reward and reinforcement, with female rats consuming higher amount of alcohol in operant paradigms compared to male rats. However, sex differences in the neuroplastic changes produced by acute alcohol in the dorsal striatum have been unexplored.

Methods:

Using electrophysiological recordings from dorsal striatal slices obtained from adult male and female rats, we investigated the effects of ex vivo ethanol exposure on synaptic transmission and synaptic plasticity. Ethanol (44 mM) enhanced basal synaptic transmission in both sexes. Ethanol also enhanced long-term potentiation in both sexes. Other measures of synaptic plasticity including paired-pulse ratio were unaltered by ethanol in both sexes.

Results:

The results suggest that alterations in synaptic plasticity induced by acute ethanol, at a concentration associated with intoxication, could play an important role in alcohol-induced experience-dependent modification of corticostriatal circuits underlying the learning of goal-directed instrumental actions and formation of habits mediating alcohol seeking and taking.

Conclusions:

Taken together, understanding the mechanism(s) underlying alcohol induced changes in corticostriatal function may lead to the development of more effective therapeutic agents to reduce habitual drinking and seeking associated with alcohol use disorders.

Individual Differences in Ethanol Drinking and Seeking Behaviors in Rats Exposed to Chronic Intermittent Ethanol Vapor Exposure is Associated with Altered CaMKII Autophosphorylation in the Nucleus Accumbens Shell

Chronic intermittent ethanol vapor exposure (CIE) in rodents produces reliable and high blood ethanol concentration and behavioral symptoms associated with moderate to severe alcohol use disorder (AUD)—for example, escalation of operant ethanol self-administration, a feature suggestive of transition from recreational to addictive use, is a widely replicated behavior in rats that experience CIE. Herein, we present evidence from a subset of rats that do not demonstrate escalation of ethanol self-administration following seven weeks of CIE. These low responders (LR) maintain low ethanol self-administration during CIE, demonstrate lower relapse to drinking during abstinence and reduced reinstatement of ethanol seeking triggered by ethanol cues when compared with high responders (HR). We examined the blood ethanol levels in LR and HR rats during CIE and show higher levels in LR compared with HR. We also examined peak corticosterone levels during CIE and show that LR rats have higher levels compared with HR rats. Lastly, we evaluated the levels of Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) in the nucleus accumbens shell and reveal that the activity of CaMKII, which is autophosphorylated at site Tyr-286, is significantly reduced in HR rats compared with LR rats. These findings demonstrate that dysregulation of the hypothalamic–pituitary–adrenal axis activity and plasticity-related proteins regulating molecular memory in the nucleus accumbens shell are associated with higher ethanol-drinking and -seeking in HR rats. Future mechanistic studies should evaluate CaMKII autophosphorylation-dependent remodeling of glutamatergic synapses in the ventral striatum as a plausible mechanism for the CIE-induced enhanced ethanol drinking and seeking behaviors.

Hippocampal neural progenitor cells play a distinct role in fear memory retrieval in male and female CIE rats

Adult male and female GFAP-TK transgenic rats experienced six weeks of chronic intermittent ethanol vapor inhalation (CIE). During the last week of CIE, a subset of male and female TK rats were fed with Valcyte to ablate neural progenitor cells (NPCs). Seventy-two hours after CIE cessation, all CIE and age-matched ethanol naïve controls experienced auditory trace fear conditioning (TFC). Twenty-four hours later all animals were tested for cue-mediated retrieval in the fear context. Adult male CIE rats showed a significant burst in NPCs paralleled by reduction in fear retrieval compared to naïve controls and Valcyte treated CIE rats. Adult female CIE rats did not show a burst in NPCs and showed similar fear retrieval compared to naïve controls and Valcyte treated CIE rats, indicating that CIE-mediated impairment in fear memory and its regulation by NPCs was sex dependent. Valcyte significantly reduced Ki-67 and NeuroD labeled cells in the dentate gyrus (DG) in both sexes, demonstrating a role for NPCs in reduced fear retrieval in males. Valcyte prevented adaptations in GluN2A receptor expression and synaptoporin density in the DG in males, indicating that NPCs contributed to alterations in plasticity-related proteins and mossy fiber projections that were associated with reduced fear retrieval. These data suggest that DG NPCs born during withdrawal and early abstinence from CIE are aberrant, and could play a role in weakening long-term memory consolidation dependent on the hippocampus.

Sexual dysfunction in patients with alcohol and opioid dependence

There are limited numbers of studies which have evaluated the sexual dysfunction (SD) in patients with alcohol and opioids dependence. This article reviews the existing literature. Electronic searches were carried out using the PubMed, Google Scholar, and ScienceDirect to locate the relevant literature. Subjects addicted to heroin or on methadone maintenance treatment (MMT) or buprenorphine maintenance treatment (BMT) show higher rates of SD in comparison to the general population. SD rates have ranged 34-85% for heroin addicts, 14-81% for MMT, 36-83% for BMT, and 90% for naltrexone maintenance. The rates of SD in alcohol-dependent population have ranged 40-95.2%, with rates being consistently much higher in alcohol-dependent population than in the healthy controls or social drinkers. The common SDs reported have been erectile dysfunction followed by premature ejaculation, retarded ejaculation and decreased sexual desire among men, and dyspareunia and vaginal dryness among women. This review suggests that long-term use of alcohol and opioids are associated with SD in almost all domains of sexual functioning. There is a need to increase the awareness of clinicians about this association as many times SD in patients with substance abuse lead to poor treatment compliance and relapse. Further, there is a need to carry out more number of studies to understand the relationship in a better way.

Urocortin 1 inhibits rat leydig cell function

Corticotropin-releasing factor (CRF) has previously been reported in rat testes in which it inhibits Leydig cells activity. However, recent studies in our laboratory have suggested that some of the effects originally attributed to CRF were instead due to the related peptide Urocortin 1 (Ucn 1) and that this latter hormone, not CRF, was detectable in Leydig cells. We show here that Ucn 1 [a mixed CRF receptor (CRFR) type 1 and CRFR2 agonist] and the CRFR1-selective peptide Stressin 1, but not Ucn 2 or Ucn 3 (both considered selective CRFR2 ligands), significantly blunt the testosterone response to human chorionic gonadotropin. The effect of Ucn 1 is observed regardless of whether this peptide is injected iv or directly into the testes, and it is reversed by the mixed CRFR1/R2 antagonist Astressin B. Blockade of GnRH receptors with the antagonist Azalin B does not interfere with the influence of Ucn 1, thereby demonstrating that pituitary luteinizing hormone does not appear to be involved in this model. Collectively these results suggest that Ucn 1, not CRF, is present in the rat testes and interferes with Leydig cell activity. However, whereas we previously reported that alcohol up-regulated gonadal Ucn 1 gene expression, CRF receptor antagonists were unable to reverse the inhibitory effect exerted by alcohol on human chorionic gonadotropin-induced testosterone release. The functional role played by testicular Ucn 1 in stress models characterized by blunted androgen levels therefore needs to be further investigated.

Profound effects of burn and ethanol on proinflammatory cytokines of the reproductive axis in the male mouse

Thermal injury is often associated with previous ethanol exposure, and close to 50% of patients admitted to a burn unit have a potentially high blood ethanol level. Cellular mechanisms by which ethanol and/or burn affect the hypothalamic-pituitary-gonadal (HPG) axis are not entirely understood. However, it is known that the proinflammatory cytokines, tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 influence negatively on the endocrine functions of the HPG. We report a time course study (6, 12, 24, and 48 hours) of the effects of ethanol, burn, or the combination of burn/ethanol on proinflammatory cytokines of the hypothalamus, pituitary and testes of male C57Bl/6 mice. We found that there were highly significant increases in each of these cytokines caused by ethanol, burn, and burn/ethanol compared with sham/vehicle (P < .001). This was true in hypothalamus, pituitary, and testes. Because these cytokines generally reduce reproductive function, it may be that proinflammatory cytokines of HPG axis mediate the deleterious effects of burn and/or ethanol on mammalian reproduction.

Vitamin E prevents ethanol-induced inflammatory, hormonal, and cytotoxic changes in reproductive tissues

Ethanol causes decreased function of the hypothalamic-pituitary-gonadal (HPG) axis. Ethanol resulted in inflammatory changes in HPG manifested by increased concentrations of pro-inflammatory cytokines. Since, such cytokines have deleterious effects on functions of HPG, it seemed possible that ethanol's suppressive action could be due, at least in part, to this inflammation. Since oxidative stress can cause inflammation, we have used the antioxidant vitamin E to test, whether reducing inflammation might protect reproductive functions from ethanol. Rats were fed an ethanol diet or pair fed identically without ethanol for a 3-week period. For the last 10 days, animals were given 30 IU/kg or 90 IU/kg or vehicle. Ethanol significantly increased hypothalamic, pituitary and testicular TNF-alpha and IL-6, all changes prevented by the higher dose of vitamin E. Also, ethanol induced changes in LHRH, LH, testosterone, and testicular germ cell apoptosis were similarly prevented by vitamin E. These data strikingly show that vitamin E protects the HPG from deleterious effects of ethanol and suggests that the mechanism of this protection might be both anti-inflammatory and antioxidant.

Systemic Administration of Alcohol to Adult Rats Inhibits Leydig Cell Activity: Time Course of Effect and Role of Nitric Oxide

BACKGROUND

Alcohol has been shown to interfere with testosterone (T) release from Leydig cells. However, the mechanisms responsible for this phenomenon, which may include decreased activity of the luteinizing hormone-releasing hormone (LHRH)-LH axis, as well as a direct influence of the drug on the testes, are not fully understood. In this work, we investigated the influence of alcohol, administered intragastrically (i.g.) or delivered via vapors, on Leydig cell activity and T release. Leydig cell function was studied by measuring changes in the levels of the steroidogenic proteins steroidogenic acute regulatory (StAR), the peripheral-type benzodiazepine receptor (PBR), and the cytochrome P450 side-chain cleavage enzyme (P450scc). Testosterone release was studied under basal conditions or in response to human chorionic gonadotropin (hCG). Finally, to identify potential factors mediating the influence of alcohol, we measured the testicular variant of the neuronal nitric oxide (NO) synthase (NOS), TnNOS, in semipurified Leydig cells.

METHODS

Adult male Sprague-Dawley rats were either injected with alcohol i.g. once or exposed to alcohol vapors (4 h/d) for 1 or 5 days. Controls received the vehicle (i.g. model) or were kept in boxes through which no vapors were circulated. Following these treatments, one series of experiments was devoted to investigate Leydig cell responsiveness by measuring plasma T levels before or after the intravenous injection of hCG (1 U/kg). In another series of experiments, we used semipurified Leydig cell preparations to measure StAR, PBR, P450scc, and TnNOS by Western blot analysis.

RESULTS

In the i.g. model, the T response to hCG was blunted for 12 hours following alcohol injection, but showed a rebound at 48 hours. Levels of StAR protein and of PBR, but not of P450scc, were significantly decreased within 10 minutes of drug administration. While StAR then remained depressed for 24 hours, PBR values were variable over this time course. By 48 hours, StAR, PBR, and P450scc levels had increased above control values. Both StAR and PBR levels showed correlations with plasma T levels. In the alcohol vapor models, both regimens of the drug also significantly depressed StAR and PBR protein concentrations, blunted the T response to hCG, and did not alter P450scc. Finally, we observed that alcohol delivered i.g. or via vapors up-regulated TnNOS levels in Leydig cells, but that blockade of NO formation failed to restore a normal T response to hCG.

CONCLUSIONS

Collectively, these results suggest that (a) the ability of Leydig cells to release T does not show a simple correlation with changes in StAR, PBR, and P450scc levels; (b) the time course of the alcohol-induced changes were protein-specific; and (c) despite the ability of alcohol to stimulate TnNOS expression, NO does not appear to mediate the inhibitory influence of this drug on testicular steroidogenesis in the models that we studied.

Comparison Between the Influence of the Systemic and Central Injection of Alcohol on Leydig Cell Activity

BACKGROUND

Systemic alcohol exposure lowers plasma testosterone (T) levels in adult males, but the relative role of impaired luteinizing hormone (LH)-releasing hormone synthesis and decreased pituitary LH release versus that of a direct ability of circulating alcohol to inhibit testicular steroidogenesis remains poorly understood. We had reported preliminary evidence that alcohol might stimulate a pituitary-independent, neural pathway between the hypothalamus and the testes whose activation blunts T secretion in response to human chorionic gonadotropin (hCG). The present work was done to further investigate the influence of alcohol on this pathway by comparing the effect of the intragastric (i.g.) and intracerebroventricular (i.c.v.) injection of alcohol on the T response to hCG, to probe the role of LH and corticotropin-releasing factor (CRF) in both models, and to examine potential changes in levels of the cholesterol transfer protein steroidogenic acute regulatory (StAR) protein.

METHODS

Male Sprague Dawley rats were implanted with chronic i.c.v., i.g., and/or intravenous cannulae that allowed drug delivery and blood sampling in nonanesthetized, undisturbed animals. T blood levels were measured by radioimmunoassay. The role of LH and of hormones of the hypothalamic-pituitary-adrenal axis such as adrenocorticotropic hormone and corticosterone was investigated in rats pretreated with an LH-releasing hormone antagonist or CRF antibodies. The potential presence of neuronal damage was assessed by Fluoro-Jade methodology. StAR protein levels were measured by Western blot in Leydig cells isolated from rats injected with the vehicle or alcohol.

RESULTS

Although it was not accompanied by measurable blood alcohol levels, i.c.v. administered alcohol, at a dose (5 microl of 200 proof, 86 microM) that did not cause neuronal damage and did not lead to detectable levels of the drug in the cerebrospinal fluid of the fourth ventricle of the brain, significantly blunted hCG-induced T release. The ig injection of alcohol, which in contrast induced significant increases in blood alcohol levels, also significantly interfered with the ability of hCG to induce T release. This effect was comparable in 40- and 65-day-old rats. Neither prior blockade of LH-releasing hormone receptors with a potent LH-releasing hormone antagonist nor immunoneutralization of endogenous CRF altered the inhibitory effect of alcohol injected i.c.v. or i.g. on T secretion. Preliminary results suggested that testicular levels of StAR protein may be slightly decreased by both alcohol regimens.

CONCLUSIONS

Collectively, our results indicate that alcohol can act within the brain to influence testicular activity independently of LH, independently of hormones of the hypothalamic-pituitary-adrenal axis, and/or independently of the presence of the drug in the circulation. Our present working hypothesis is that the i.c.v. injection of alcohol stimulates an inhibitory neural pathway that connects the hypothalamus to the testes.

Ethanol-induced hypogonadism is not dependent on activation of the hypothalamic-pituitary-adrenal axis

The well-characterized suppression of the male reproductive unit after ethanol (EtOH) exposure has been speculated to be partially due to activation of the hypothalamic-pituitary-adrenal (HPA) axis. The subsequent corticosterone elevation could result in hypogonadism via suppression of hypothalamic LHRH, pituitary LH, or a direct gonadal effect. To directly examine this possibility, adult male Sprague Dawley rats were either adrenalectomized (ADX) or sham ADX. The ADX animals were given low dose corticosterone via replacement pellet, resulting in a steady level of serum corticosterone. The sham ADX (adrenal intact) animals were implanted with placebo pellets. Half of both groups were then exposed to EtOH by I.P. injection on two consecutive days to mimic an acute binge-drinking model. The other half was given saline I.P., serving as controls. In the adrenal intact animals, EtOH caused the expected rise in corticosterone, and fall in luteinizing hormone (LH) and testosterone. In the ADX animals, where constant levels of corticosterone were maintained by pellet implantation, EtOH resulted in similar LH and testosterone reduction. These results suggest that suppression of the reproductive axis is independent of the activation of the HPA unit.

Effect of alcohol on the proestrous surge of luteinizing hormone (LH) and the activation of LH-releasing hormone (LHRH) neurons in the female rat

Reproduction is adversely affected by alcohol abuse in humans and laboratory animals. In rats, alcohol exposure suppresses both luteinizing hormone (LH) and sex steroid secretion, although consensus is lacking as to which level of the hypothalamic-pituitary-gonadal (HPG) axis is primarily affected. We tested the hypothesis that acute alcohol treatment inhibits the HPG axis by blunting release of LH-releasing hormone (LHRH) in female rats, by examining the effect of this drug on the central reproductive endocrine event; i.e., the proestrous surge of gonadotropins, which triggers ovulation. In a first series of experiments, we injected alcohol at 8 A.M. and 12 P.M. on proestrus and measured plasma levels of LH, estradiol (E2), and progesterone during the afternoons of proestrus and estrus. Alcohol administration blocked the proestrous surge of LH and ovulation. In subsequent experiments, alcohol inhibited the surge of LHRH (measured by push-pull cannulation) and LHRH neuronal activation (measured by Fos labeling in LHRH neurons). Because alcohol also decreased E2 levels, we reasoned that it might have prevented positive feedback; however, alcohol retained its ability to inhibit the LH surge evoked by E2 implantation in ovariectomized females, disproving this hypothesis. Additionally, alcohol does not act via increased corticosteroid secretion, because alcohol also blocked the proestrous surge in adrenalectomized females. Last, exogenous administration of LHRH to alcohol-blocked animals evoked LH secretion and ovulation, indicating that pituitary and/or ovarian function could be restored by mimicking the hypothalamic signal. Collectively, these data indicate that in female rats, alcohol inhibits the gonadotropin surge primarily by decreasing LHRH secretion.

Alcohol rapidly lowers plasma testosterone levels in the rat: evidence that a neural brain-gonadal pathway may be important for decreased testicular responsiveness to gonadotropin

Alcohol is reported to suppress testosterone (T) secretion in the adult male rat. Decreases in the circulating levels of luteinizing hormone (LH) and/or the activity of testicular steroidogenic enzymes have been proposed as putative mechanisms underlying this inhibitory effect. We have recently provided functional evidence for a neural pathway between the brain and the male gonads that plays an important role in the ability of brain proinflammatory cytokines to blunt testicular responsiveness to human chorionic gonadotropin (hCG). The present work was designed to test the hypothesis that a similar pathway might be implicated in the inhibitory influence of alcohol on T secretion. Alcohol, administered intraperitoneally or intragastrically, significantly prevented the T response to the gonadotropin. This effect was significant within 15 min of drug treatment. In the intragastric model (the only one used for this type of experiment), the effect of alcohol was not altered by prior blockade of LH release, which suggests that it is independent of changes in the activity of the pituitary gonadotrophs. The lowest effective dose of alcohol, delivered intraperitoneally, was 2.0 g/kg. The intracerebroventricular injection of the alpha- and beta-adrenergic receptor antagonists phentolamine and propranolol significantly reversed the inhibitory influence of alcohol when it was administered 15 min, but not 60 min, before hCG. Collectively, our results indicate that (1) alcohol induces a rapid and profound decrease in plasma T levels that is secondary to decreased testicular responsiveness to hCG; and (2) at least part of this acute inhibitory action of alcohol may depend on the activation of a neural, adrenergic-dependent pathway between the brain and the testes.

Chronic alcohol consumption and withdrawal do not induce cell death in the suprachiasmatic nucleus, but lead to irreversible depression of peptide immunoreactivity and mRNA levels

There is evidence that chronic ethanol treatment (CET) disrupts the biological rhythms of various brain functions and behaviors. Because the suprachiasmatic nucleus (SCN) is widely recognized as the dominant pacemaker of the circadian system, we have examined the effects of CET and withdrawal on the main morphological features and chemoarchitecture of this hypothalamic nucleus. Groups of rats ethanol-treated for 6 and 12 months were compared with withdrawn rats (ethanol-treated for 6 months and then switched to a normal diet for an additional 6 months) and with groups of age-matched control and pair-fed control rats. The volume and the total number of neurons of the SCN were estimated from conventionally stained material, whereas the total number of astrocytes and of neurons containing vasopressin (AVP), vasoactive intestinal polypeptide (VIP), gastrin-releasing peptide (GRP), and somatostatin (SS) were estimated from immunostained sections. The estimates were obtained using unbiased stereological methods, based on Cavalieri's principle and the optical fractionator. The volume of the SCN and the total number of SCN neurons and astrocytes did not vary among groups. We found, however, that CET induced a significant reduction in the total number of AVP-, VIP-, GRP-, and SS-containing neurons. Withdrawal from alcohol did not reduce but rather augmented the loss of VIP- and GRP-immunoreactive neurons. The CET-induced neurochemical alterations seem to result from a decrease in neuropeptide synthesis, as revealed by the reduction in AVP and VIP mRNA levels demonstrated by in situ hybridization with radioactively labeled 48-mer AVP and 30-mer VIP probes. It is thus possible to conclude that the irreversible CET-induced changes in the neurochemistry of the SCN might underpin the disturbances in circadian rhythms observed after long-term alcohol consumption.

Sustained effects of a single injection of ethanol on the hypothalamic-pituitary-gonadal axis in the male rat

The hormones responsible for regulating the hypothalamic-pituitary-gonadal axis are essential for proper reproductive function. Ethanol (EtOH) has been shown to exert its effect at all three levels of this axis. The present study defines striking differences in the time course of recovery of luteinizing hormone (LH) in gonadally intact, compared with, castrated male rats after acute EtOH administration. Serum levels of LH and testosterone were measured at various time points up to 2 weeks (1.5, 3, 24, 48, 72, 96, 168, and 336 hr) after a single intraperitoneal injection of either saline or 3 g/kg of EtOH in intact adult male rats. One EtOH injection significantly suppressed testosterone levels as low as 20% (p < 0.01) of saline-injected intact rats. This occurred as early as 1.5 hr after EtOH administration (the first measured time point), and statistically significant suppression was sustained for 96 hr. Similarly, LH levels showed a significant decrease. However, this significant fall in LH did not begin until 3 hr (p < 0.05) and continued up to 96 hr (p < 0.01), with a gradual return to control levels at 168 and 336 hr after treatment. Despite the significant and prolonged fall in testosterone levels in the EtOH-treated intact rats, beta-LH mRNA levels were inappropriately not elevated, as would be expected in the context of low circulating testosterone. However, at 168 and 336 hr, steady-state levels of beta-LH mRNA were significantly higher than seen in saline-injected controls (p < 0.05 and p < 0.01, respectively), temporally correlating with the return of serum LH to control. LH levels in the castrated animals were significantly suppressed at 1.5 hr (p < 0.05) and 3 hr (p < 0.01) after EtOH treatment, compared with controls, yet they returned much more quickly by 24 hr after treatment. beta-LH mRNA levels of castrated animals also showed a significant depression at 1.5 and 3 hr, and returned to control levels by 24 hr. In these rats, the hypothalamic LH-releasing hormone mRNA levels were not altered by a single EtOH injection at any time point. However, in the intact animals, there was a transient increase in LH-releasing hormone mRNA at 72 and 96 hr (p < 0.01 and p < 0.05, respectively) that may lead to the upregulation of beta-LH mRNA expression. These studies indicate that EtOH causes prolonged decreases in important serum hormones that are essential to the reproductive axis of the adult male rat.

Gender difference in alcohol-evoked hypothalamic-pituitary-adrenal activity in the rat: ontogeny and role of neonatal steroids

Alcohol administration results in activation of the hypothalamic-pituitary-adrenal (HPA) axis, with female rats secreting more adrenocorticotropin (ACTH) and corticosterone (B) than males in response to the same dose of alcohol. We first examined the ontogeny of the gender difference in HPA responsiveness to alcohol by administering four doses (0, 1, 2, or 3 g/kg body weight) to animals at 21, 41, and 61 days of age (prepubertal, peripubertal, and postpubertal, respectively). We then investigated the organizational role of steroids by manipulating the neonatal steroidal milieu. Rats of both genders were gonadectomized or injected with testosterone propionate within 24 hr of birth and the HPA response to 3 g/kg body weight alcohol was tested in adulthood (postpubertal period). Our data show that the gender difference in HPA responsiveness to alcohol administration arises peripubertally. In addition, HPA response to alcohol is quantitatively smaller in intact male rats than in feminized groups (gonadectomized males and females, intact females) and masculinized female rats. We conclude that the gender difference in HPA response to alcohol observed in postpubertal rats injected with alcohol depends on the activational role of testicular androgens, rather than on their organizational influence.

Further characterization of the impact of ethanol on βLH: alterations in polyribosome association of βLH mRNA

We have previously reported a decrease in Luteinizing Hormone (LH) levels in serum afterin vivo acute ethanol exposure in male rats. Accompanying these changes, a rapid and marked decrease of β-LH mRNA was observed. A similar decrease was not detected in the common α-subunit or β-FSH mRNA. The studies presented here examined the possible mechanisms of decreasing β-LH mRNA by using S1 nuclease protection assay to evaluate the effect of acute ethanol exposure on the levels of β-LH heteronuclear RNA (hnRNA). There was no significant difference detected in the level of β-LH hnRNA after ethanol exposure. Polysome distribution analysis was used to evaluate the association and disassociation of β-LH mRNA with polyribosomes since non-polyribosome associated mRNA may be more vulnerable to degradation by RNAases. The results indicated a decrease in the association of the β-LH mRNA with polysomes following acute ethanol exposure. This decrease in polyribosome association would increase the exposure of the β-LH transcript making it more susceptible to RNases. We conclude that the decrease in steady-state β-LH mRNA levels after ethanol exposure occurs because of increasing degradation of the transcript rendered vulnerable by displacement from polysomes and not through a decreased transcriptional rate.

Female rats release more corticosterone than males in response to alcohol: influence of circulating sex steroids and possible consequences for blood alcohol levels

The hypothalamic-pituitary-adrenal (HPA) axis of female rats is more responsive to a variety of stimuli than that of males. Proestrous females are also reported to release more ACTH and corticosterone in response to restraint stress than females at other stages of the estrous cycle. Finally, blood alcohol levels (BALs) reached in response to a standard dose of alcohol also indicate the presence of a gender specificity, with females exhibiting higher BALs than males. The aim of this study was therefore 2-fold: first, we investigated the influence of gender on the ability of alcohol to increase plasma ACTH and corticosterone secretion in the rat. Second, we tested the hypothesis that corticosterone alters alcohol metabolism and asked whether this might represent a mechanism underlying the sex difference in BALs. We observed that compared with intact males, intact females taken at random stages of the estrous cycle secreted significantly (p < 0.01) more ACTH and corticosterone in response to alcohol (0.2-1.8 g/kg). Within females, the intraperitoneal administration of alcohol was followed by higher plasma ACTH and corticosteroids levels during proestrus and estrus, compared with diestrus. Removal of circulating sex steroids abolished the gender difference in terms of ACTH secretion, but ovariectomized females still released more corticosterone than castrated males in response to 0.6 and 1.8 g alcohol/kg. This difference could not be explained by a sex-related component of pituitary responsiveness to corticotropin-releasing factor.(ABSTRACT TRUNCATED AT 250 WORDS)