Effects of sexual intercourse on testicular function

Abstract

Objective: We evaluated the effects of sexual intercourse on testicular function in fertile and infertile rats. Design: Markers of Leydig and Sertoli cell secretory functions were evaluated prior to and during sexual intercourse in fertile and infertile rats. Materials/Methods: Each one of four-month-old-Wistar male rats of groups A1 (n=10; fertile rats), A2 (n=10; fertile rats), B1 (n=10; bilaterally cryptorchid infertile rats), and B2 (n=10; bilaterally cryptorchid infertile rats) was placed at the same cage with 2 female rats in oestrus. Immediately after the entrance of the male rat into the cage all the males of groups A1 and B1 were killed. Intratesticular testosterone profiles (ITPs), testicular transferrin profiles and androgen binding protein profiles (ABPPs) in testicular cytosols were evaluated. Rats of groups A2 and B2 were allowed to have a sexual intercourse. Immediately after the first ejaculation (first postejaculatory interval) rats of groups A2 and B2 were killed and ITPs, testicular transferrin levels, and ABPPs were evaluated. Prior to sacrificing each rat of groups A1, A2, B1 and B2 blood was collected from the tail vein of this male rat and the serum levels of FSH, LH, testosterone and prolactin were evaluated. Detected spermatozoa in the vaginae of the females confirmed the performance of complete intercourses. Ten and 12 additional four-month-old fertile male Wistar rats (group C and group D, respectively)were allowed to have sexual intercourse with female rats in oestus (one male was placed in the same cage with two females). However, at the time of intercourse the males of group C were disturbed by visual and audial stimuli. ITPs and ABPPs were evaluated immediately after the first ejaculation in all rats of group C. Rats of group D were killed during intromissions prior to ejaculation. ITPs and ABPPs were evaluated in each rat of group D. Results: ITPs were significantly larger (p <0.05; Wilcoxon’s test) in the group A2 (136 ± 13 ng/g testis) than in group A1 (114 ± 10 ng/g testis) and in the group B2 (91 ± 11 ng/g testis) than in group B1 (73 ± 7 ng/g testis). In contrast there were no significant differences in serum FSH, LH, testosterone and prolactin levels and in testicular ABPPs and transferrin concentrations between groups A1 and A2, and between groups B1 and B2. ITPs and testicular ABPPs were significantly smaller in groups C and D than in group A2. The latter parameters were significantly larger in groups C and D than in group A1. Conclusions: Sexual intercourse results in an increase in the ITPs in both fertile and infertile subjects. In contrast sexual intercourse does not affect Sertoli cell secretory function. This increase in ITPs appears not to be due to an enhanced pituitary gonadotropin secretion and is partially inhibited when the sexual intercourse is interrupted or the male is disturbed during sexual intercourse. Whether multiple sexual intercourses in infertile subjects increasing ITPs have a positive influence in spermatogenesis needs to be evaluated. Supported by: Research Grant from MFC Clinic, Yonago, Japan.