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

Beer consumption negatively regulates hormonal reproductive status and reduces apoptosis in Leydig cells in peripubertal rats

Beer is one of the most popular alcoholic beverages consumed by young people. Ethanol intake is associated with harmful effects to the reproductive system. Bioactive compounds present in beer may diminish the toxics effect of ethanol. However, there is still little knowledge about the effect of beer consumption on hormonal regulation of male reproduction in organisms exposed to alcohol after the peripubertal age. Therefore, the aim of this study was to determine the influence of beer intake on plasma reproductive hormones, immunolocalization of cleaved caspase-3 (casp-3), and the level of the neuronal isoform of nitric oxide synthase (nNOS) in Leydig cells (LCs) in adolescent male Wistar rats. The animals, beginning at the age of 30 days, drank beer (10% ethanol; B2 group [2 weeks' exposure] and B4 group [4 weeks' exposure]), 10% ethanol solution (CE2 group [2 weeks' exposure] and CE4 group [4 weeks' exposure]), or water (C2 group [2 weeks' exposure] and C4 group [4 weeks' exposure]). Rats drinking beer for 4 weeks showed higher phenolic acid intake compared to rats drinking beer for 2 weeks. Rats exposed to beer for 4 weeks showed decreased plasma levels of follicle-stimulating hormone (FSH) and 17β-estradiol (E2) (3.173 ng/mL and 11.49 pg/mL, respectively), compared to the CE4 (5.293 ng/mL and 43.912 pg/mL, respectively) and the C4 groups (5.002 ng/mL and 41.121 pg mL, respectively). Expression of cleaved caspase-3 in LCs was lower in the B4 group rats, compared to the CE4 group rats (ID score: 1.676 vs. 2.190). No changes in nNOS expression were observed. Beer consumption revealed a similar negative effect on hormonal regulation of male reproductive function, but lower apoptosis in LCs may be beneficial for steroidogenic activity.

Alcohol consumption and hormonal alterations related to muscle hypertrophy: a review

Detrimental effects of acute and chronic alcohol (ethanol) consumption on human physiology are well documented in the literature. These adversely influence neural, metabolic, cardiovascular, and thermoregulatory functions. However, the side effects of ethanol consumption on hormonal fluctuations and subsequent related skeletal muscle alterations have received less attention and as such are not entirely understood. The focus of this review is to identify the side effects of ethanol consumption on the major hormones related to muscle metabolism and clarify how the hormonal profiles are altered by such consumption.

Ascorbic acid supplementation enhances recovery from ethanol induced inhibition of Leydig cell steroidogenesis than abstention in male guinea pigs

The impact of ascorbic acid supplementation against ethanol induced Leydig cell toxicity was studied in guinea pigs. Male guinea pigs were exposed to ethanol (4g/kgb.wt.) for 90 days. After 90 days, ethanol administration was completely stopped and animals in the ethanol group were divided into abstention group and ascorbic acid supplemented group (25mg/100gb.wt.) and those in control group were maintained as control and control+ascorbic acid group. Ethanol administration reduced the serum testosterone and LH (luteinising hormone) levels and elevated estradiol levels. Cholesterol levels in Leydig cell were increased whereas the mRNA and protein expressions of StAR (steroidogenic acute regulatory) protein, cytochrome P450scc (cytochrome p450side chain cleavage enzyme), 3β-HSD (3β-hydroxysteroid dehydrogenase), 17β-HSD (17β-hydroxysteroid dehydrogenase) and LH receptor were drastically reduced. Administration of ascorbic acid resulted in alteration of all these parameters indicating enhanced recovery from ethanol induced inhibition of Leydig cell steroidogenesis. Although abstention could also reduce the inhibition of steroidogenesis, this was lesser in comparison with ascorbic acid supplemented group.

Urocortins are present in the rat testis

The synthesis and release of testosterone (T) depends both on circulating luteinizing hormone (LH) and on an array of testicular factors whose role remains incompletely understood. Corticotropin-releasing factor (CRF) had been reported in the rat testes, where it was thought to inhibit T secretion. However, the discovery that the CRF-related peptides urocortins (Ucns), of which there are currently three subtypes (Ucn 1, 2 and 3), cross-react with many reagents previously used to detect CRF, has cast doubt on this concept. Here we show that while CRF was readily measurable in rat hypothalami (which served as controls), signals for this peptide were barely detectable in total RNA extracted from the testes. On the other hand, microarray, RT-PCR and real-time quantitative RT-PCR (qRT-PCR) analyses all indicated strong signals for Ucn 1 in the male gonads, with weaker levels of Ucn 2 and 3 mRNA gene expression. Results obtained for Ucn 1 gene expression were corroborated by immunohistochemical detection, which appeared restricted to Leydig cells. Finally, to investigate possible changes in testicular Ucn 1 levels induced by homeostatic challenges, we measured them in rats exposed to alcohol. We observed that indeed, the intragastric injection of this drug significantly increased testicular Ucn 1, but not Ucn 2, Ucn 3, CRF, CRFR1 or CRFR2 mRNA levels. Collectively, these results provide novel information regarding the presence of CRF-like peptides in the adult male rat testis.

Neuropeptide Y acts within the rat testis to inhibit testosterone secretion

The factors that influence Leydig cell activity currently include peptides such as neuropeptide Y (NPY). In this work we investigated the ability of this compound, injected directly into the testes of adult male rats, to alter testosterone (T) release into the general circulation. At a 5μg/kg dose administered 1h prior to challenge with human chorionic gonadotropin (hCG, 1.0 U/kg, iv), NPY significantly (P<0.01) blunted the T response to this gonadotropin. The inhibitory effect of NPY was observed in animals pretreated with an antagonist to gonadotropin-releasing hormone or not, indicating that the decrease in plasma T found was most likely independent of pituitary luteinizing hormone. However, testicular levels of steroidogenic acute regulatory (STAR) protein or translocator protein (TSPO) in the Leydig cells did not exhibit consistent changes, which suggested that other mechanisms mediated the blunted T response to hCG. We therefore used autoradiography and immunohistochemistry methodologies to identify NPY receptors in the testes, and found them primarily located on blood vessels. Competition studies further identified these receptors as being Y(1), a subtype previously reported to modulate the vasoconstrictor effect of NPY. The absence of significant changes in STAR and TSPO levels, as well as the absence of Y(1) receptors on Leydig cells, suggest that NPY-induced decreases in T release is unlikely to represent a direct effect of NPY on these cells. Rather, the very high expression levels of Y(1) found in testicular vessels supports the concept that NPY may alter gonadal activity, at least in part, through local vascular impairment of gonadotropin delivery to, and/or blunted T secretion from, Leydig cells.

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.