Serotonin Concentration, Synthesis, Cell Origin, and Targets in the Rat Caput Epididymis During Sexual Maturation and Variations Associated With Adult Mating Status: Morphological and Biochemical Studies

Abstract

ABSTRACT:The caput epididymis of some mammals contains large quantities of serotonin whose origin, targets, and physiological variations have been poorly studied. We combined morphological and biochemical techniques to begin approaching these aspects of serotonin in the rat caput epididymis. Serotonin immunostaining was detected in mast, epithelial, and neuroendocrine cells. Epithelial cells displayed immunoreactivity to 5HT 1A , 5HT 2A, and 5HT 3 serotonin receptors. Endothelial and mast cells labeled positive for 5HT 1B serotonin receptors and spermatozoa displayed 5HT 2A and 5HT 3 serotonin receptor immunoreactivity. Epithelial, endothelial, and mast cells stained positive for serotonin transporters. Only epithelial cells showed tryptophan hydroxylase immunoreactivity; this enzyme catalyzes the limiting step in the serotonin synthetic pathway. In addition, Western blot analyses of caput homogenates documented the presence of 2 protein bands (<51 kd and <48 kd) that were immunoreactive for tryptophan hydroxylase. Chromatographic analyses documented the presence of tryptophan hydroxylase in the caput, and showed that both its activity and serotonin availability increased with sexual maturation and decreased following p-chlorophenylalanine treatment, an inhibitor of tryptophan hydroxylase activity. Interestingly, serotonin concentration and tryptophan hydroxylase activity tended to be higher in breeding males than in those with no mating experience. We think that these results support the existence of a local serotoninergic system in the rat caput epididymis that might regulate some aspects of male reproductive function.

Proliferative and Nonproliferative Lesions of the Rat and Mouse Male Reproductive System

“…In rodents, the presence of prominent mast cells in the interstitium of the epididymis is a common background finding that should not be confused with inflammation. The number of mast cells reportedly varies with sexual maturation, reaching a peak at approximately 90 days of age (Jiménez-Trejo et al 2007). …”

Evidence of 5-HT components in human sperm: implications for protein tyrosine phosphorylation and the physiology of motility

“…We recently found that both 5-HT concentration and TPH activity increase in the epididymis during sexual maturation and in breeding males when compared with naive ones (Jiménez-Trejo et al 2007) and also that epididymal serotonin concentration correlated with reproductive fitness, offspring number, mating success, and seminal plug volume in copulatory males (Pichardo et al 2011).…”

Estimation of changes in spermogram and index of sperm DNA fragmentation in patients with premature ejaculation receiving Neurodoz biocomplex

“…Это позволя-ет предположить, что у мужчин с ПЭ может иметь место пони женная чувствительность рецепторов 5-HT2C или гиперсенситивность рецепторов 5-HT1A [12]. На сегод-няшний день доказано существование локальной серо-тонинергической системы в клетках Сертоли, Лейдига и придатке яичка, а также влияние серотонина на стеро-идогенез путем связывания с рецепторами клеток [13][14][15].…”