Evidence for a direct inhibitory effect of ethanol upon gonadotropin secretion at the pituitary level

The chronic alcohol consumption influences the gonadal axis in men: Results from a meta-analysis

BACKGROUND

Low testosterone concentrations affect 2-13% of adult males, with a direct association between reduction in testosterone (T) concentrations and cardiovascular events. Lifestyle habits have been linked to visceral fat accumulation and endocrine disorders like secondary hypogonadism. Alcohol intake has also been a topic of debate, with studies showing a detrimental effect on sperm production and underlying mechanisms. This meta-analysis aims to comprehensively evaluate the effect of alcohol consumption on T serum concentrations in adult men.

METHODS

The literature search included only controlled clinical trials comparing men who drink alcohol to men who do not, or who assumed placebo or nonalcoholic beverages. The primary outcome was the comparison of total testosterone serum concentrations between the study and control groups. The publications were examined for publication bias using Egger's test.

RESULTS

Twenty-one studies were included in the analysis for a total of 30 trials that examined the effects of alcohol consumption on testosterone level in 10,199 subjects. The meta-analysis showed that alcohol consumption overall is related to significant reduction in circulating concentrations of total testosterone (mean difference [MD] = -4.02; 95% CI -6.30, -1.73), free T (MD = -0.17; 95% CI -0.23, -0.12), sex hormone binding globulin (SHBG) (MD = -1.94; 95% CI -3.37, -0.48), an increase in estradiol (E2) (MD = 7.65; 95% CI 1.06, 14.23) and neutral effect on luteinizing hormone (LH) (MD = -0.15; 95% CI -0.36, 0.06), independently by age, body mass index (BMI), E2, and LH serum concentrations and alcohol intake. However, these results are evident only in healthy men exposed to chronic alcohol consumption and not in those with a recognized diagnosis of alcohol use disorder or after acute alcohol intake.

CONCLUSION

This study suggests how chronic alcohol consumption may inhibit the gonadal axis in healthy men, although the exact pathophysiological mechanisms connecting alcohol exposure and steroidogenesis are still not completely clarified.

Exposure to ethanol induces oxidative damage in the pituitary gland

Chronic exposure of pubertal male rats to ethanol results in a decline in serum testosterone and decreased or inappropriately normal serum luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels suggesting a functional defect in the pituitary. The molecular mechanisms behind this disorder are undefined. A role for ethanol-induced oxidative damage in the pathophysiology is supported by studies in liver, muscle, and heart of experimental animals, but there is limited evidence in the pituitary. We examined markers of oxidative damage to lipids and proteins in pituitaries from rats consuming ethanol for 5, 10, 20, 30, and 60 days in addition to markers of damage to nucleic acids in pituitaries after 60 days of ethanol exposure. There were increases in 8-oxo-deoxyguanosine immunoreactivity, a marker of oxidative damage to nucleic acids, and an overall increase in malondialdehyde and 4-hydroxynonenal, markers of lipid peroxidation. Protein carbonylation and protein nitrotyrosination, markers of protein oxidation, were significantly increased after 30 days and 60 days of ethanol consumption, respectively. After 60 days of ethanol exposure, TUNEL assay revealed that cell death in the ethanol-treated pituitaries was not significantly different from that in the pair-fed controls at the time of examination. We also measured serum testosterone, FSH, and LH after ethanol consumption for 5, 10, 20, 30, and 60 days. Through 5 to 60 days of ethanol exposure, testosterone levels were consistently lower whereas LH and FSH were inappropriately unchanged, suggesting pituitary malfunction. These results provide evidence for ethanol-induced oxidative damage at the pituitary level, which may contribute to pituitary dysfunction.

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.

Failure of ethanol metabolites to alter gonadotropin secretion or luteinizing hormone synthesis in vitro

The impact of ethanol on the male reproductive axis are multiple and varied, with both gonadal and control hypothalamic-pituitary pertubations being reported. There appears to be a discrepancy, however, between the in vivo and in vitro effects of ethanol on hypothalamic luteinizing hormones releasing hormone (LHRH) and the pituitary gonadotropins luteinizing hormone (LH) and follicle stimulating hormone (FSH). While in vivo data suggests a decrease in LHRH release after EtOH, in vitro studies find no effect on secretion. Similarly, in vivo acute EtOH profoundly diminishes LH synthesis and secretion, while in vitro impaired release with no alteration in the transcription of beta LH has been found. A potential exploration for these discrept results could be the in vivo metabolism of EtOH into acetaldehyde and acetate, or the subsequent formation of salsolinol, a product of acetate combining with dopamine. To test this possibility, a series of in vitro experiments were conducted exposing dispensed anterior pituitary cells from male rats to different doses of acetaldehyde, acetate or salsolinol for varying amounts of time for which gonadotropin secretion and beta LH mRNA levels were assessed. The results demonstrated no effect of either acetaldehyde or acetate on basal or LHRH stimulated LH release, FSH release or steady-state beta LH mRNA levels. These data suggest that the metabolites of EtOH, which occur in vivo but not in vitro, are not responsible for the discrepant gonadotropin changes reported between the in vivo and in vitro setting. Other potential mechanisms to explain this phenomenon include differences in the molarity of EtOH, hyperprolactinemia and suprapituitary influences including hypothalamic LHRH, catecholamines, excitatory amino acids, substance P and beta endorphin.

The effect of in vitro ethanol exposure on luteinizing hormone and follicle stimulating hormone mRNA levels, content, and secretion

It has been previously shown that acute ethanol (EtOH) exposure in vivo resulted in suppression of serum LH and pituitary beta-LH subunit mRNA levels in castrated male rats. While serum FSH levels also were noted to fall after in vivo, the mRNA for beta-FSH was not altered. The aim of the present studies was to determine whether these effects could be accounted for by a direct EtOH effect at pituitary level. To this end we examined the direct effect of EtOH on LH and FSH synthesis and secretion utilizing dispersed anterior pituitary cells from gonadectomized adult male rats. After a 72 hour post dissociation healing period, the cells were exposed to media containing 0 or 200 mg% EtOH for one hour. The media was removed and the cells incubated with EtOH-free media for an additional 1, 3 or 6 hrs. In the EtOH exposed cells, secretion of both LH and FSH increased to > 300% (p < 0.001) of control. At 6 hrs after withdrawal of EtOH a significant reduction in both LH and FSH secretion was seen. Intracellular content of LH and FSH was unchanged before and after withdrawal of EtOH. Steady state levels of beta LH and beta FSH mRNA were unchanged at all time points. In a separate series of experiments, pituitary cells from gonadectomized adult male rats were continuously exposed to different concentrations of EtOH ranging from 0-400 mg% for 3 hrs. LH secretion was stimulated by 400 mgm% EtOH only, while the intracellular content of LH was significantly reduced with the 400 mg% dose. The secretion of FSH was stimulated by 200 mg% and 400 mg% high dose EtOH after 3 hours, with concomitant reduction in FSH pituitary content at both these EtOh dose levels. The mRNA for both beta-LH and beta FSH was not different with any dose of EtOH compared to levels of control, non-EtOH exposed cells. We conclude that though there were similarities between in vivo and in vitro LH and FSH responses to EtOH, the differences reported here indicate that the in vivo responses are not totally explained by a direct EtOH effect at pituitary level. Rather, they must, in addition, reflect action at suprapituitary site(s), pituitary effects of EtOH metabolites or condensation products, and/or alterations in LH and FSH clearance.

[Disorders of the hypothalamo-hypophyseal-ovarian axis in chronic alcoholic women]

This paper deals with the physiology of menstrual cycle disturbances in alcoholic women. Nineteen women, aged from 25 to 45 years, were investigated for the quality of their menstrual cycle (amenorrhoea in 6, spanomenorrhoea in 5, normal cycle in 8) and for their clinical, biochemical and, when possible, histological hepatic status. In all these women, hormone levels were measured (in the early follicular phase for those with normal menses), including E2, E1, LHRH test, T, delta 4A, SBG, T4L, T3L, cortisol and prolactin. According to their hormonal profile, these women were classified as hypothalamo-pituitary amenorrhoea (n = 4), premature menopause (n = 2), ovarian dystrophy (n = 1) and normal hormone levels (n = 12). Although our results are too few for statistic value, it appears that the amount of alcohol consumed, the degree of malnutrition and the hepatic abnormalities observed are more important in women with abnormal hormonal profile.

In vitro effect of ethanol on LH and FSH secretion by pituitary glands of female rats

The effect of ethanol (EtOH) on LH and FSH release in vitro has been studied in order to determine whether the effect of alcohol observed in vivo could be mediated by a direct action at the level of the anterior pituitary. Pituitary glands were incubated for 4 hours in TC-199 medium with or with 100 mM ethanol. Basal gonadotrophin release was examined as well as secretion stimulated by luteinizing hormone releasing hormone (LHRH) in the presence or absence of cycloheximide. The total amount of LH and FSH released during the incubation period was calculated. Ethanol did not significantly alter basal gonadotrophin release or LHRH-stimulated FSH release. However, LH secretion induced by LHRH was decreased by EtOH when compared to the LHRH-stimulated group. Cycloheximide decreased the LHRH-stimulated release of LH and FSH but this effect was not altered by EtOH. The results show that EtOH alters the release but not the synthesis of gonadotrophins by a direct effect on the anterior pituitary gland.

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

Alcohol (EtOH) is reported to decrease gonadotropin secretion, but the mechanisms mediating these changes are not fully understood. The present study examined the ability of acutely or chronically administered EtOH to alter plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels in both male and female rats, and correlated these changes with blood EtOH levels (BALs); investigated possible changes in the pituitary responsiveness of animals exposed to EtOH; and probed the role of the paraventricular nucleus (PVN) of the hypothalamus in mediating alcohol-induced decreases in plasma LH levels. The injection of 0.5 g EtOH/kg was accompanied by significantly higher BALs in females compared with males. This dose of alcohol did not alter rectal temperature, and only significantly (p < or = 0.01) decreased plasma LH levels in female rats. These findings were not altered by removal of gonadal steroids. Administration of 2.0 g EtOH/kg was followed by BALs that were comparable in both groups of rats at the 1- and 2-hr time-points, but were significantly (p < or = 0.01) higher in females 3 hr after treatment. Rectal T measurably decreased in all rats injected with 2 g EtOH/kg, though intact females showed the greatest change. This alcohol treatment also significantly (p < or = 0.01) inhibited immunoreactive LH release in both sexes, but there were no measurable changes in FSH values at any time.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of in vitro ethanol exposure on LHRH release from perifused rat hypothalami

A variety of indirect data suggest that the luteinizing hormone (LH) lowering effects of ethanol (ETOH) are mediated at a hypothalamic level decreasing the synthesis and/or release of LH-releasing hormone (LHRH). Little direct data support this concept, however. The current study was, therefore, designed utilizing a perifusion system with frequent sampling for LHRH with and without ethanol added to determine if ethanol had a direct effect on basal or stimulated LHRH release. A variety of secretagogues, including dopamine, norepinephrine, naloxone, prostaglandin E2, and a high dose of potassium were utilized. Ethanol at a dose of 300 mg% did not alter either basal or secretagogue-stimulated LHRH release from the hypothalami of ethanol-naive male rats. Thus, ethanol did not appear to have a direct effect on LHRH in this system. Alterations in LHRH release by ethanol may occur at a suprahypothalamic level, involving neurotransmitter-LHRH interactions. Alternatively, the well-described lowering effect of ethanol on LH may be secondary to a direct pituitary locus of action, or involve a metabolic breakdown product of ethanol rather than ethanol itself.

Alcohol effects on LH and FSH in ovariectomized female monkeys

The acute effects of alcohol (2.5, 3.0, 3.5 g/kg) and sucrose control solution on basal levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were compared in recently and chronically ovariectomized female rhesus monkeys. Integrated plasma samples were collected at 20 min intervals for 3 hr before and 6 hr after nasogastric intubation of alcohol or isocaloric sucrose control solution. Baseline levels of LH and FSH were significantly higher in recently than in chronically ovariectomized females (p less than 0.001). Baseline LH pulse frequency was also significantly higher (p less than 0.001) in the recently ovariectomized group than in the chronically ovariectomized group (0.704 +/- 0.03 vs. 0.379 +/- 0.10 pulses/hr). FSH pulse frequency was equivalent in both groups (0.444 +/- 0.06 to 0.360 +/- 0.06 pulses/hr). After 2.5 g/kg of alcohol, peak blood alcohol levels were 243 to 256 mg/dl and LH decreased significantly (p less than 0.01) in both groups. After 3.0 g/kg alcohol, peak blood alcohol levels were 237 to 289 mg/dl, and basal LH levels (p less than 0.05) and LH pulse frequency (p less than 0.05) decreased significantly only in the recently ovariectomized group. After 3.5 g/kg of alcohol, peak blood alcohol levels exceeded 320 mg/dl, and LH did not change significantly in either group. Administration of 3.5 g/kg alcohol was associated with increased LH pulse amplitude in some individuals. Since lower alcohol doses (2.5 and 3.0 g/kg) and sucrose control administration were followed by a significant decline in LH (p less than 0.05-0.01) and the highest alcohol dose (3.5 g/kg) was not, these data suggest the possible influence of nonspecific "stress" on modulation of LH secretory activity. FSH did not change after sucrose administration in recently ovariectomized monkeys, but was significantly suppressed after 2.5 and 3.5 g/kg alcohol (p less than 0.05). In the chronically ovariectomized monkeys, FSH decreased significantly after administration of sucrose and all alcohol doses. LH suppression was not consistently associated with changes in FSH in either group--a finding consonant with the hypothesis that LH and FSH may be controlled by different hypothalamic regulatory factors.

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

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

In vitro effect of ethanol exposure on basal and GnRH-stimulated LH secretion from pituitary cells

The question of whether ethanol's (ETOH's) known suppressive effect on serum luteinizing hormone (LH) could be mediated directly at the anterior pituitary level was addressed by examining the effects of ETOH in vitro on release of LH from cultured male rat pituitary cells. The impact of added ethanol concentrations ranging from 50 to 400 mg% on LH release was examined in the basal state and after stimulation by gonadotropin-releasing hormone (GnRH) at a dose of 5 x 10(-10) M. While ETOH did not significantly suppress basal LH release, secretion stimulated with GnRH was noted to be attenuated with higher doses of ETOH (greater than or equal to 100 mg%) compared to stimulated control cells. It is concluded that ETOH exposure in vitro alters stimulated LH secretion by acting directly on pituitary gonadotropes.

The effect of in vitro ethanol exposure on basal growth hormone secretion

Suppressive effects of ethanol (ETOH) on in vivo serum growth hormone (GH) levels have been reported in both humans and animals. To determine whether this effect could be mediated directly at the pituitary level, we have designed a series of in vitro experiments utilizing pituitary cells from ETOH naive animals maintained in monolayer culture. We report that ETOH, in doses ranging from 50 to 400 mg%, caused a prompt and sustained reduction in basal GH secretion, as well as a significant fall in intracellular GH content. These data establish that the in vivo effects of ETOH on GH can be accounted for, at least in part, by a direct effect at the pituitary level, possibly due to reduced GH synthesis.

International Commission for Protection against Environmental Mutagens and Carcinogens. ICPEMC Working Paper No. 15/7. Reproductive consequences of alcohol abuse: males and females compared and contrasted

The adverse effects of ethyl alcohol on the hypothalamic pituitary gonadal axes of men and women are discussed with particular attention being given to effects of alcohol upon reproduction. Data obtained from acute and chronic alcohol exposure studies are presented. The putative pathophysiologic mechanisms responsible for disturbed reproductive performances in alcohol abusing individuals are discussed where sufficient data are available.

Delayed pubertal development of the male reproductive tract associated with chronic ethanol ingestion

Little is known concerning the sensitivity of the reproductive tract to ethanol as a function of development. The present study was conducted to evaluate the action of chronic ethanol ingestion on sexual maturation of the male. Mice were given free access to liquid diets containing 5% (v/v) ethanol for either 29 or 43 days, starting at age 20 days. Controls were given liquid diets in which isocaloric sucrose replaced the ethanol. Daily diet consumption and peak blood ethanol levels were highest during the first 2 weeks of treatment, dropping thereafter to adult levels of approximately 680 ml/kg body weight and 160 mg/dl respectively. Plasma testosterone levels were depressed by ethanol throughout treatment, the reduction being somewhat greater when measured during week 6 of treatment (average = 74% inhibition) as compared to either week 2 (36%) or week 4 (25%). Average weights of testes, epididymides and seminal vesicles were depressed by 24% (P less than 0.002), 16% (P less than 0.005) and 13% (NS), respectively, after 29 days. Testicular development was also impaired in ethanol-treated animals after 29 days. Tunica albuginea thickness and seminiferous tubule diameter were decreased (by 31%, P less than 0.05; and 16%, P less than 0.01 respectively), whereas desquamation of immature germ cells and inactive tubules were increased (325 and 780% respectively; P less than 0.01). Quality of spermatogenesis was poorer in ethanol-treated animals (P less than 0.05). Also observed were decreased sperm motility (62% inhibition, P less than 0.01) and capacity to fertilize (decreased by 67%, P less than 0.01), and an increase in the incidence of morphologically abnormal spermatozoa (by 163%, P less than 0.001). Semen volume was lower (reduced by 57%, P = 0.05), as was the total number of motile ejaculated spermatozoa (reduced by 81%, P less than 0.05). After 43 days treatment, improvement was noted in all indices of fertility except for the number of motile ejaculated spermatozoa. Significant differences persisted only for dysmorphic spermatozoa and volume and sperm count of electroejaculated semen. These data suggest that ethanol ingestion during pubertal development can delay several aspects of sexual maturation in the male.

Effects of ethanol on steroid profiles in the rat testis

The effects of ethanol on the concentrations of steroids in testis was studied in adult rats. Testosterone, seven of its potential precursors, three of its metabolites, and estradiol were analyzed by gas chromatography-mass spectrometry of samples from testes removed 2 h after intraperitoneal administration of ethanol, 1.2 g/kg body weight. The same analyses were made on samples from control rats. Ethanol gave a marked increase of all 3 beta-hydroxy-delta 5 steroids analyzed: pregnenolone (60%), 17-hydroxypregnenolone (480%), dehydroepiandrosterone (430%) and 5-androstene-3 beta, 17 beta-diol (60%). This resulted in highly significant increases of the 3 beta-hydroxy-delta 5/3-oxo-delta 4 steroid ratios for all steroid couples analyzed. An analogous increase of the ratio between 5 alpha-androstane-3 beta, 17 beta-diol and dihydrotestosterone was also observed, whereas the ratio between androstenediol and dehydroepiandrosterone was decreased by ethanol. The concentration of estradiol was not affected. The results indicate that moderate doses of ethanol inhibit the conversion of 3 beta-hydroxy-delta 5 to 3-oxo-delta 4 steroids. This may be one mechanism by which ethanol decreases the production of testosterone.

Plasma concentrations of sex hormones in postmenopausal women in non-alcoholic cirrhosis

Sex hormone and sex hormone binding globulin (SHBG) levels were measured in the plasma of postmenopausal women with non-alcoholic liver cirrhosis (n = 24) and compared with levels in matched controls (n = 21). Plasma oestradiol was elevated: 80 vs 30 pmol/l, P less than 0.005 (median values). Plasma SHBG was elevated, 15 vs 10 mg/dl, P less than 0.001. Plasma dehydroepiandrosterone sulphate levels were low, 0.35 vs 2.0 mumol/l, P less than 0.0005, as were plasma androstenedione levels, 2.5 vs 4.5 nmol/l, P less than 0.05. There was no significant difference in plasma testosterone. These data suggest that liver disease per se alters sex hormone and sex hormone binding globulin levels in postmenopausal women.

Demonstration of a functional blood-testis barrier to acetaldehyde. Evidence for lack of acetaldehyde effect on ethanol-induced depression of testosterone in vivo

In vitro studies have shown that acetaldehyde is a more potent inhibitor of testicular steroidogenesis than ethanol. The present study examined the in vivo role of acetaldehyde in ethanol-induced reduction of testosterone by (1) determining the levels of acetaldehyde to which the testes were exposed subsequent to acute ethanol administration to mice; and (2) examining the effect of ethanol on testosterone in animals subsequent to drug pretreatment which decreased or increased ethanol-derived acetaldehyde. Ethanol-induced (3 g/kg) depression of testosterone was dependent upon gonadotropin stimulation. The increase in hCG-induced testosterone was suppressed (P less than 0.01) in ethanol- as compared to saline-treated animals [39.8 +/- 2.6 (S.E.M.) vs 28.1 +/- 2.3 ng/ml]. Pargyline (100 mg/kg) or cyanamide (8.4 mg/kg) increased (P less than 0.05) plasma and testicular acetaldehyde, while having no effect on the testosterone response to ethanol. Similarly, 4-methylpyrazole (25 mg/kg) reduced blood and testicular acetaldehyde to nondetectable levels, while having no effect on testosterone. Testicular acetaldehyde was lower (P less than 0.001) than plasma levels (14 +/- 2 vs 2.0 +/- 0.2 microM). This functional blood-testis barrier to acetaldehyde could be explained by testicular aldehyde dehydrogenases in the mitochondria (Km for acetaldehyde = 1.5 microM) and in the cytosol (Km = 123 microM) whose maximal activities totaled to more than 25-fold greater than that of testicular alcohol dehydrogenase (ADH). ADH was concentrated in the Leydig cells, while aldehyde dehydrogenase was evenly distributed in the testis. Ethanol prevented further hCG-induced rises in testosterone rather than inhibiting testosterone production to below pre-ethanol values. The above data argue against a significant role of acetaldehyde in the in vivo response of testosterone to ethanol. Ethanol appears to impair gonadotropin-testicular receptor interaction in vivo.

Development of sexual behavior in prenatally ethanol-exposed rats

Female rats were given 16% ethanol solution as the sole liquid during the entire period of gestation. At birth the offspring was removed and reared by foster dams consuming normal drinking water. When tested for feminine sexual behavior in adulthood, the males showed marked signs of feminization as evidenced by an increased amount of lordosis responses. No changes were seen in the masculine sexual behavior. No deviations were seen in the female estrous cycles or in onset of vaginal estrus, whereas the onset of behavioral estrus was delayed. It is suggested that prenatal ethanol exposure may lower the fetal testosterone production and thereby interfere with the normal course of sexual differentiation in the male.