Intrahipotalamic ghrelin administration decreases sperm concentration and motility in mice

Abstract

Ghrelin (Ghr) is a peptide secreted primarily in the stomach and hypothalamus. However, Ghr and its receptors are synthesized also in many tissues of the reproductive tract. In situations of hiperghrelinemia (fasting or undernutrition), the peptide exerts predominantly inhibitory effects on the hypothalamic-pituitary-testicular function. Thus, it could be hypothesized that beyond the effects of the peptide on testosterone secretion, Ghr could directly affect other testicular processes such as spermatogenesis. In this study we investigated the effects of intrahypothalamic Ghr administration for 7 days (covering the period of sperm maturation in the epididymis) or 42 days (covering both period spermatogenesis and epididymal maturation) on sperm functional activity. Adult male Albino Swiss mice were implanted intrahipotalámicamente with osmotic pumps (Alzet) model 1007D (0.5 μl/h) or model 2006 (0.15 μl/h-42 days) and infused with different Ghr doses (0.3 or 3.0 nmol/μl) or the vehicle: sterile cerebrospinal fluid (CSF-control) or. Epididymal sperm functional activity was determined at the end of the treatment, evaluating: concentration, motility, maturation, viability, hypoosmotic shock response and acrosome integrity. The results show that none of the Ghr doses administered for 7 days induced significant changes in sperm functional activity. We did find a decrease in the sperm concentration and motility in animals treated with Ghr 3.0 nmol/μl for 42 days (sperm concentration (x106 /ml): Ghr 17.68 ± 2.98 vs. LCR 26.91 ± 1.52, p ≤ 0.05, sperm motility (%): Ghr 56.25 ± 1.80 vs. LCR 77.67 ± 1.33, p ≤ 0.05). No significant differences were observed in any of the other parameters tested, with any of the Ghr doses or infusion periods evaluated. Our results suggest that hypothalamic Ghr administration can affect sperm quality only when the treatment period includes both spermatogenesis and epididymal maturation