Ethanol directly increases dihydrotestosterone conversion primarily to 5 alpha-androstan-3 beta, 17 beta-diol in rat Leydig cells

Effects of ethanol ingestion on epididymal glycosidases and fertility in the rat

Epididymal glycosidases play a role in sperm maturation by modifying sperm surface glycoproteins. To study the effects of ethanol on epididymal sperm maturation, ethanol (3 g/kg body weight as 25%, v/v) was administered to a group of rats by gastric-intubation twice daily for 30 days. In another group, rats were also treated with alcohol for 30 days but were then withdrawn from treatment for 30 days to assess the reversibility of ethanol-induced effects. Ethanol-induced changes in epididymal tissue and sperm glycosidases, cauda epididymal sperm motility and the fertility of rats were assessed. Ethanol treatment caused a marked decrease in the specific activities of glycosidases in both tissues and spermatozoa from epididymal segments. Cauda epididymal sperm motility and the fertility of ethanol-treated rats were significantly impaired compared to control rats fed an isocaloric diet. These changes are likely to be the consequence of direct and indirect effects of ethanol mediated through subnormal testosterone and dihydrotestosterone. Most of these changes were found to be reversible. The present study suggests that impaired activity of sperm glycosidases may be one of the factors responsible for defective sperm motility and fertilizing potential in ethanol-treated rats.

Control of alcohol metabolism

The rate of alcohol metabolism is determined by the kinetic characteristics and concentrations of the alcohol and aldehyde dehydrogenases and by the rate of restoration of the redox state of the cell. Several potent competitive and uncompetitive inhibitors of the alcohol dehydrogenases can decrease the rate of alcohol metabolism; they may be useful for preventing the potentially deleterious effects of ethanol metabolism. Alcohol dehydrogenases have very broad specificity and can readily reduce a variety of carbonyl compounds by exchange reactions while ethanol is metabolized. Agents that increase the rate of metabolism need to be developed.

Transfer of deuterium from [1,1-2H2]ethanol to steroids and organic acids in the rat testis

Rats were given [1,1-2H2]ethanol in a single dose, and the 2H content was determined in testicular steroids and in organic acids of low molecular mass in the testis, liver and blood. The acids were quantified by capillary gas chromatography/mass spectrometry of t-butyldimethylsilyl derivatives with [2H4]lactate as internal standard. In addition to lactate, pyruvate, 3-hydroxybutyrate and acids of the tricarboxylic acid cycle, the testis was shown to contain 2-hydroxybutyrate, 2-hydroxy-2-methylbutyrate, 2-hydroxyisohexanoate and glycerate. No 2H was found in pregnenolone, 5-androstene-3 beta,17 beta-diol or testosterone, whereas the abundance of monodeuterated molecules of 5 alpha-androstane-3 alpha,17 beta-diol and its 3 beta-isomer were 7.6% and 11.2% respectively. The abundance of monodeuterated lactate was 7.0% in the testis and 5.3% in the blood. The other acids were less labelled but 3-hydroxybutyrate had a higher 2H content in the testis (3.1%) than in the liver. These results support the contention that ethanol is oxidized in an alcohol dehydrogenase-catalysed reaction in testis in vivo and that the acute inhibition of the testosterone production is due at least partly to a redox effect. The labelling and increased concentration of 3-hydroxybutyrate in the testis indicate that a change in the mitochondrial redox state might be involved.

Effects of chronic ethanol intake on aromatization of androgens and concentration of estrogen and androgen receptors in rat liver

The present study was carried out to investigate if ethanol alters aromatization of androgens and concentrations of hepatic estrogen and androgen receptors. Hepatic aromatization of androgen to estrogen was significantly increased by ethanol administration. There was a significant increase in serum estrogen level but a decreased circulating testosterone level in alcohol-fed rats. Furthermore, the concentration of estrogen receptors in liver cytosol was significantly higher in alcohol-fed rats (37 +/- 5.3 fmol/mg protein), as compared to the intact control value (21 +/- 4.8 fmol/mg protein). However, hepatic androgen receptor levels were much lower (4.4 +/- 0.5) in alcohol-fed rats than those (10.2 +/- 1.4 fmol/mg protein) in control animals. Similarly, castration increased hepatic aromatization of androgens and concentrations of serum estrogen and hepatic estrogen receptors, but it decreased contents of circulating androgen and hepatic androgen receptors. These findings indicate that alcohol administration is considered a chemical form of castration, altering the hepatic steroid metabolism and sex hormone receptor contents and contributing to the pathogenesis of feminization. A combination of alcohol-feeding and castration has no synergistic effect on the hepatic steroid receptors and aromatization, but this combination does have a more profound effect in lowering the concentration of circulating androgen.

Inhibition of testosterone biosynthesis by ethanol: multiple sites and mechanisms in dispersed Leydig cells

Isolated rat Leydig cells were incubated for 2 h in sealed polycarbonate tubes under O2/CO2 atmosphere with 10 mIU/ml human chorionic gonadotropin. 20 mmol/l ethanol reduced the concentration of testosterone (16%, P less than 0.025); raised the concentrations of pregnenolone (60%, P less than 0.001), androstenedione (86%, P less than 0.001) and dehydroepiandrosterone (81%, P less than 0.001); but did not change concentrations of progesterone and 17 alpha-hydroxyprogesterone in the incubation medium. Ethanol also raised the lactate/pyruvate ratio in the Leydig cell suspension. 4-Methylpyrazole (0.5 mmol/l) abolished the ethanol-induced changes. The present results suggest that ethanol inhibits testosterone synthesis in isolated rat Leydig cells at the pregnenolone-to-testosterone pathway by inhibiting 3 beta-hydroxy-5-ene-steroid dehydrogenase/5-ene-4-ene-isomerase catalyzed reactions and the conversion of androstenedione to testosterone. These inhibitions are caused by consequences of ethanol metabolism. A likely mechanism for the former inhibition is that the increase in the NADH/NAD+ ratio in Leydig cells leads to inhibition of reactions catalyzed by 3 beta-hydroxy-5-ene-steroid dehydrogenase/5-ene-4-ene isomerase, but the inhibition mechanism operating at the androstenedione-to-testosterone step remains to be characterized.

Microsomal ethanol-oxidizing system in purified rat Leydig cells

These studies provide evidence for the presence of a microsomal ethanol oxidizing system in rat Leydig cells. Activity of the microsomal ethanol oxidizing system in Leydig cells was 47.4 +/- 4.1 nmol acetaldehyde per 20 min per mg protein, while activity in crude interstitial cells was 26.0 +/- 5.4 nmol. This suggests that among cells comprising interstitial cells, activity is concentrated in Leydig cells. Activity was linear with respect to protein concentration and incubation time. The highest specific activity was observed in the microsomal fraction. The most effective cofactor was NADPH. The apparent Km for ethanol was 4 mM, suggesting that this system could effectively metabolize ethanol at concentrations found in the blood of males who drink. The apparent Km for NADPH was 11 microM. The activity in Leydig cells was unaffected by 4-methylpyrazole or potassium cyanide, which inhibit alcohol dehydrogenase and catalase activities, respectively. These data provide strong evidence for an enzyme system in Leydig cell microsomes which is capable of metabolizing ethanol.

Preferential alcoholic embryopathy among contiguous siblings of Long-Evans rats

Ethanol exposure alters sex steroidogenesis and sexually dimorphic behaviors in rodent offspring. Contiguity to siblings of the same or opposite sex in utero also affects steroidogenesis and sexual dimorphism in rodents. The present study with Long-Evans rats shows that maternal exposure to ethanol during the critical period of rodent organogenesis preferentially affects body weights and increases malformations in offspring dependent on their in utero contiguity to siblings of the opposite sex.

Partial characterization of alcohol dehydrogenase activity in purified rat Leydig cells

Ethanol metabolism to acetaldehyde by NAD+-dependent alcohol dehydrogenase (ADH) activity reduces, in part, androgen secretion by rat Leydig cells. ADH in Leydig cells is proposed to decrease the NAD+/NADH ratio and thereby inhibit NAD+-dependent delta 5-3 beta hydroxysteroid dehydrogenase-isomerase activity and increase NADH-dependent 5 alpha-androstane-3 beta-hydroxysteroid dehydrogenase activity. Although the reciprocal changes in these steroidogenic enzyme activities by ethanol are attributed to ADH activity, there is very little information about this enzyme in purified Leydig cells. The present studies examined specific characteristics of this enzyme in metrizamide-gradient purified Leydig cells. ADH activity was linear with respect to protein concentration and incubation time. The activity was concentrated in the soluble fraction, and the most effective cofactor was NAD+. The apparent Km for ethanol was 0.50 mM, and the Vmax was 53 nmol NADH/10 min/mg protein. When Leydig cell cytosol was incubated with a fixed ethanol concentration (50 mM) and increasing NAD+ and the data were plotted according to Lineweaver-Burk, a biphasic curve was observed with apparent Km's of 0.032 and 0.17 mM. The optimum pH for the enzyme was 8.2, and the enzyme was inhibited in a dose-dependent manner by 4-methylpyrazole. These studies further characterize ADH activity in purified Leydig cells and demonstrate that this enzyme exhibits many characteristics similar to the more widely studied liver enzyme(s).(ABSTRACT TRUNCATED AT 250 WORDS)