Effects of Chronic Ethanol Diet on Pituitary-Testicular Function of the Rat1

Abstract

We studied the effects of a 6% ethanol liquid diet administered for 5 wk on the pituitary-gonadal function of adult male rats. Because ethanol is known to reduce body weight, we used sucrose-fed animals as controls. No significant differences in body, testis, or prostate weights were found between the rats exposed to ethanol and their sucrose-fed controls at the end of the 5-week treatment. Seminal vesicle weights decreased significantly (p less than 0.05) in the ethanol-treated group. Serum and testicular testosterone concentrations were significantly reduced in the ethanol-treated group, to 43.6% and 48.3% of levels in the sucrose-fed controls, respectively (p less than 0.05). Serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels of the ethanol-treated rats were 37.9% and 41.3%, respectively, of those of the sucrose-fed controls (p less than 0.01-0.05). The pituitary levels of these hormones were similar to those of controls, but the ratios of pituitary LH and FSH to their serum levels were clearly increased after ethanol exposure, to 492% and 206.1%, respectively (p less than 0.05). In contrast, pituitary prolactin (PRL) of the ethanol-treated rats was decreased to 40.2% (p less than 0.01) of sucrose-fed controls. Testicular content of LH receptors was significantly reduced (to 77.0% of controls; p less than 0.01), but content of FSH receptors was slightly increased by the ethanol diet (to 121.5% of sucrose-fed controls; p less than 0.05). No ethanol-associated changes were apparent in testicular PRL and gonadotropin-releasing hormone (GnRH) receptors or in pituitary GnRH receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Ethanol Treatment on Leydig Cellular NADPH-Generating Enzymes and Lipid Profiles.

“…The reduced serum testosterone level may be due to defects in various parts of the hypothalamo-hypophyseal-testicular hormone axis, such as the inhibition of LHRH release [36] and thus low LH [1,2], and at the level of the Leydig cells by reducing LH receptors [37][38][39] and steroidogenic enzyme [3]. In general, the reduced levels of both LH and testosterone are suggestive of hypogonadotropic hypogonadism and an impaired feed back system due to ethanol treatment.…”

“…The decreased serum LH and its receptors in Leydig cells [38,39] may be responsible for the decreased activity of NADPH generating enzymes, as LH is the principal regulating factor in Leydig cellular structure and function [41]. In vitro studies by Akane et al [3] have suggested that ethanol (1, 5, 20 and 100 mM) has a direct inhibitory effect on Leydig cellular 3/3-HSD and 17, 20 lyase.…”

Ethanol Decreases the Expression of Pituitary Adenylate Cyclase Activating Polypeptide in Rat Testes

“…Also, chronic ethanol exposure for 30 days has been shown to cause testicular atrophy and accessory reproductive organ dysfunction in adult male rats [3]. Another study showed that ethanol exposure decreases male reproductive ability through the reduction of testosterone production and the suppression of spermatogenesis and steroidogenesis [13].In testicular germ cells, pituitary adenylate cyclase activating polypeptide (PACAP) has been shown to stimulate cAMP production and to contribute to spermatogenesis [5,9]. PACAP has considerable homology with secretin, glucagon, vasoactive intestinal peptide, and growth hormone releasing hormone [10,11].…”

Decrease of Pituitary Adenylate Cyclase Activating Polypeptide and Its Type I Receptor mRNAs in Rat Testes by Ethanol Exposure

“…Also, we confirmed that ethanol exposure significantly reduced serum testosterone levels in adult male rats. Previous studies demonstrated that ethanol suppresses male reproductive activity through the inhibition of testosterone release by reduction of LH secretion from the pituitary gland [23,25]. Also, it has been shown that the reduction of LH levels by ethanol decreases testosterone release through the inhibition of steroidogenic acute regulatory protein expression in testes [14].…”

“…In particular, ethanol decreases male reproductive ability through the reduction of testosterone production by inhibition of luteinizing hormone (LH) release from pituitary gland [23,25]. In males, LH stimulates testosterone production through cAMP activation in testicular Leydig cells.…”