Effects of ethanol on steroid profiles in the rat testis

Effects of Timing of Flibanserin Administration Relative to Alcohol Intake in Healthy Premenopausal Women: A Randomized, Double-Blind, Crossover Study

INTRODUCTION

Flibanserin is approved in the United States and Canada for the treatment of acquired, generalized, hypoactive sexual desire disorder in premenopausal women. Sedation-related side effects are among the most prevalent adverse events. Although infrequent, hypotension and syncope remain safety concerns because of possible interaction of flibanserin with alcohol.

AIM

To evaluate the impact of the timing of alcohol consumption on flibanserin safety and tolerability.

METHODS

In this single-center, randomized, double-blind, placebo-controlled, 4-treatment crossover study, 64 healthy premenopausal women (mean age 32.5 ± 8.7 years; range 20‒52 years) received once-daily flibanserin 100 mg or placebo during each of two 10-day treatment periods. Study medication was administered on days 1-3 to achieve steady state. On days 4, 6, 8, and 10, after a standard breakfast, participants consumed 0.4 g/kg ethanol (approximately equivalent to two 5-oz glasses of wine) administered with orange juice 2, 4, or 6 hours before taking study medication or orange juice alone (no ethanol) 2 hours before taking study medication.

OUTCOMES

The primary endpoint was percentage of participants experiencing syncope or orthostatic hypotension-associated adverse events requiring medical intervention. Secondary endpoints included the incidence of hypotension, the incidence of orthostatic hypotension, and rates of adverse events of special interest (syncope, orthostatic hypotension, dizziness, and somnolence).

RESULTS

1 participant experienced a primary endpoint event (syncope) during treatment with placebo taken 4 hours after ethanol consumption. Within each ethanol dose-timing treatment, there were no statistically significant differences for flibanserin compared with placebo. Rates of hypotension were 53.3-66.7% after flibanserin dosing and 57.4-63.3% after placebo dosing. Rates for orthostatic hypotension were 0.0-5.0% after flibanserin dosing and 1.7-6.6% after placebo dosing.

CLINICAL IMPLICATIONS

Ethanol interaction with flibanserin was not observed in this study.

STRENGTHS & LIMITATIONS

This study provides information regarding the use of flibanserin after the consumption of moderate amounts of ethanol (0.4 g/kg). However, daytime administration of flibanserin is not consistent with the drug's indicated bedtime dosing.

CONCLUSION

Flibanserin, at steady state taken 2, 4, or 6 hours after 0.4 g/kg of ethanol intake did not increase the incidence of hypotension, orthostatic hypotension, or syncope compared with either flibanserin alone or ethanol alone. Simon JA, Clayton AH, Kingsberg SA, et al. Effects of Timing of Flibanserin Administration Relative to Alcohol Intake in Healthy Premenopausal Women: A Randomized, Double-Blind, Crossover Study. J Sex Med 2019;16:1779-1786.

Fifty years with bile acids and steroids in health and disease

Cholesterol and its metabolites, e.g., steroid hormones and bile acids, constitute a class of compounds of great biological importance. Their chemistry, biochemistry, and regulation in the body have been intensely studied for more than two centuries. The author has studied aspects of the biochemistry and clinical chemistry of steroids and bile acids for more than 50 years, and this paper, which is an extended version of the Schroepfer Medal Award lecture, reviews and discusses part of this work. Development and application of analytical methods based on chromatography and mass spectrometry (MS) have been a central part of many projects, aiming at detailed characterization and quantification of metabolic profiles of steroids and bile acids under different conditions. In present terminology, much of the work may be termed steroidomics and cholanoidomics. Topics discussed are bile acids in human bile and feces, bile acid production, bacterial dehydroxylation of bile acids and steroids during the enterohepatic circulation, profiles of steroid sulfates in plasma of humans and other primates, development of neutral and ion-exchanging lipophilic derivatives of Sephadex for sample preparation and group separation of steroid and bile acid conjugates, profiles of steroids and bile acids in human urine under different conditions, hydroxylation of bile acids in liver disease, effects of alcohol-induced redox changes on steroid synthesis and metabolism, alcohol-induced changes of bile acid biosynthesis, compartmentation of bile acid synthesis studied with 3H-labeled ethanol, formation and metabolism of sulfated metabolites of progesterone in human pregnancy, abnormal patterns of these in patients with intrahepatic cholestasis of pregnancy corrected by ursodeoxycholic acid, inherited and acquired defects of bile acid biosynthesis and their treatment, conjugation of bile acids and steroids with N-acetylglucosamine, sulfate-glucuronide double conjugates of hydroxycholesterols, extrahepatic 7alpha-hydroxylation and 3-dehydrogenation of hydroxycholesterols, and extrahepatic formation of C27 bile acids. The final part discusses analysis of free and sulfated steroids in brain tissue by capillary liquid chromatography-electrospray MS and suggests a need for reevaluation of the function of steroid sulfates in rat brain.

Metabolic conversion as a pre-receptor control mechanism for lipophilic hormones

The majority of physiological effects mediated by steroids, retinoids and thyroids is accomplished by binding to members of the nuclear receptor superfamily of ligand activated transcription factors. The complex specific effects of lipid hormones depend not only on receptor expression, distribution and interactions, but also on the availability and metabolic conversion of the hormone itself. The cell-specific metabolic activation of inactive hormone precursors introduces a further level of hormonal regulation, and constitutes an important concept in endocrinology. The metabolic reactions carried out are achieved by dehydrogenases/reductases, hydroxylases and other enzymes, acting on ligands of the steroid/thyroid/retinoic hormone receptor superfamily. The concept implies that these tissue- and cell-specific metabolic conversions contribute to lipid hormone action, thus pointing to novel targets in drug development. All components of this signalling system, the hormone compounds, the receptor proteins, and modifying enzyme families originate from an early metazoan date, emphasizing the essential nature of all elements for development and diversification of vertebrate life.

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.

Role of ethanol metabolism in the inhibition of testosterone biosynthesis in rats in vivo: importance of gonadotropin stimulation

The mechanisms by which ethanol (EtOH, 1.5 g/kg) inhibits testicular testosterone synthesis were studied in nonstimulated and human chorionic gonadotropin (hCG, 50 IU/kg)-treated male rats. To dissociate the effects caused by ethanol metabolism, the alcohol dehydrogenase inhibitor 4-methylpyrazole (4MP, 10 mg/kg) was given to half of the rats 30 min before EtOH. The 4MP had little or no effect in the nonstimulated rats on the EtOH-induced decreases in the concentrations of serum testosterone and of the intratesticular steroids of the testosterone biosynthetic pathway measured, but reduced the EtOH-induced elevation in the intratesticular pregnenolone-to-progesterone ratio. In contrast, 4MP pretreatment markedly reversed the EtOH-induced decrease in serum and intratesticular testosterone and increase in intratesticular pregnenolone concentrations in the hCG-stimulated rats. Simultaneously, the EtOH-induced elevations in the intratesticular pregnenolone/progesterone and androstenedione/testosterone ratios were abolished. In the EtOH-treated rats whose EtOH metabolism was blocked by 4MP pretreatment, the intratesticular testosterone concentrations were negatively correlated with the elevated serum corticosterone levels. It is concluded that: (1) EtOH metabolism is involved in the inhibition of testicular steroidogenesis in vivo. This effect is pronounced during gonadotropin-stimulated conditions. Thus, previously reported "discrepancies" between the in vivo and in vitro results are clarified; (2) corticosterone seems also to be involved in the EtOH-induced inhibition of steroidogenesis. This effect is also pronounced during gonadotropin-stimulated conditions; and (3) without external gonadotropin stimulation other inhibitory mechanisms, such as decreased stimulation by luteinizing hormone, are prevalent.

Ethanol-induced inhibition of testosterone biosynthesis in rat Leydig cells: role of L-glutamate and pyruvate

The mechanisms by which ethanol (EtOH) inhibits testicular testosterone biosynthesis were studied with isolated rat Leydig cells in vitro comparing the effects of EtOH in six different culture media. The actual sites of inhibition by EtOH, identified by measuring the steroidogenic precursors, varied depending on the medium used. In Krebs-Ringer bicarbonate buffer, EtOH inhibited both the conversion of pregnenolone to progesterone and androstenedione to testosterone. In the pyruvate (Pyr) supplemented Dulbecco's Modified Eagle medium, the decreased progesterone concentrations in the presence of EtOH were reflected to all successive steroids 17-OH-progesterone, androstenedione and testosterone. The presence of L-glutamate (Glu) in the medium elevated testosterone production, but EtOH still inhibited the conversion of pregnenolone to progesterone, and also the androstenedione/testosterone ratio was elevated because of the decreased testosterone concentrations. In the presence of both Glu and Pyr in the medium the EtOH-induced decreases in the steroid concentrations were fully recovered in isolated Leydig cells. These results demonstrate that both Pyr and Glu supplementations are essential for the maintenance of maximal rate of testosterone synthesis in vitro in the presence of EtOH.

Acute effects of drinking beer or wine on the steroid hormones of healthy men

Plasma Testosterone, Dihydrotestosterone and Estradiol were determined in 72 healthy volunteers, divided into 36 beer and 36 wine drinkers, who consumed between 0.9-2.1 g ethanol/kg b.wt, simulating natural patterns of drinking. Blood samples were taken 5-10 h after drinking ceased and compared with control samples withdrawn exactly 24 h previously. For a consideration of the time variation of blood sampling, the subjects were classified as fast and slow drinkers. All groups exhibited both depressed and elevated testosterone levels, depending upon the time after drinking (fast beer drinkers) and upon the amount of alcohol (fast wine drinkers). Consumption of beer and wine significantly (P less than 0.05) inhibited dihydrotestosterone biosynthesis; depending on the time after drinking (only in beer drinkers) and blood alcohol levels (slow beer drinkers). Estradiol levels were significantly elevated (P less than 0.05-less than 0.001); correlating with the amount of beer and wine/kg b.wt, with time after drinking (fast beer drinkers), and with blood alcohol levels (fast wine drinkers). Consumption of these beverages showed different dependencies for the changed hormone levels. It is discussed whether the estrogenic constituents of beer and wine might be responsible for the enhancement of estradiol, which could contribute towards clarifying the phenomenon of feminization observed with chronic abuse of alcohol.

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.

Effects of chronic ethanol ingestion on steroid profiles in the rat testis

Testosterone, seven of its potential precursors, three of its metabolites and estradiol were analyzed in testes from rats given ethanol for 23 days in a nutritionally adequate liquid diet. The results were compared to those obtained with pair-fed control rats. The concentrations of pregnenolone, progesterone, 17-hydroxyprogesterone, androstenedione and testosterone were markedly lowered in four of the five rats given ethanol. The concentrations of the other 3 beta-hydroxy-delta 5 steroids and estradiol were unchanged, resulting in significantly increased ratios between 17-hydroxypregnenolone and 17-hydroxyprogesterone (P less than 0.025) and between androstenediol and testosterone (P less than 0.025) in the ethanol-treated rats. The results indicate that chronic ethanol administration reduces formation of testosterone by affecting a step prior to pregnenolone. There may also be an effect on the conversion of some 3 beta-hydroxy-delta 5 to the corresponding 3-oxo-delta 4 steroids. The levels of testosterone and three other steroids in testes of rats given the liquid diet were significantly lower than those in testes of animals fed a standard rat chow. This indicates a dietary influence on testicular steroid concentrations.