Does follicle‐stimulating hormone or pregnant mare serum gonadotrophin influence testicular blood flow in rats?

Abstract

Treatment of adult rats with 25 iu follicle-stimulating hormone (FSH) did not influence testicular blood flow, serum testosterone, vasomotion or intravascular leucocyte concentration at 6, 12 and 24 h after treatment. Treatment of adult rats with 50 iu pregnant mare serum gonadotrophin (PMSG) resulted in a two-fold increase in testicular blood flow at 24 h, and an increase in interstitial fluid volume at 36 h after treatment. This PMSG-induced increase in blood flow did not occur in Leydig cell-depleted animals, suggesting that the effect on blood flow is mediated via the Leydig cells. PMSG injection stimulated testosterone secretion but it did not influence vasomotion, and it only marginally increased the secretion of leucotactic factors in the testis. The present study suggests that FSH has no apparent effects on testicular blood flow and that the effects of PMSG (a hormone with both FSH and LH-like activity) is mediated via stimulation of the Leydig cells.

Influence of human menopausal gonadotrophin treatment on testicular blood flow and on seminal plasma nitric oxide levels in infertile males1

“…The results of the study confirmed the positive effect of hMG on testicular blood flow supply as a significant decrease in the resistance index of intratesticular vessels at colour Doppler sonography was reported after FSH treatment. This finding agrees with those of Bergh et al. (1992), who demonstrated that the administration of PMSG in adult rats results in a twofold increase in intratesticular blood flow after 24 h. The preparation used for our study was hMG that has both FSH and LH activity similar to PMSG.…”

“…The results of the study confirmed the positive effect of hMG on testicular blood flow supply as a significant decrease in the resistance index of intratesticular vessels at colour Doppler sonography was reported after FSH treatment. This finding agrees with those of Bergh et al (1992), who demonstrated that the administration of PMSG in adult rats results in a twofold increase in intratesticular blood flow after 24 h. The preparation used for our study was hMG that has both FSH and LH activity similar to PMSG. As we did not observe any variation in serum T after treatment, the testicular haemodynamic changes that we found could not be explained by an LHinduced increase in sexual steroid secretion, via stimulation of Leydig cells as suggested by Bergh et al (1992).…”

“…(1992), who demonstrated that the administration of PMSG in adult rats results in a twofold increase in intratesticular blood flow after 24 h. The preparation used for our study was hMG that has both FSH and LH activity similar to PMSG. As we did not observe any variation in serum T after treatment, the testicular haemodynamic changes that we found could not be explained by an LH‐induced increase in sexual steroid secretion, via stimulation of Leydig cells as suggested by Bergh et al. (1992).…”

Evidence against a role for ovarian hormones in the regulation of blood flow

“…Luteinizing hormone and hCG have been shown to increase ovarian blood flow (37), but their effects on the systemic vasculature are unclear (38). Follicle-stimulating hormone does not appear to play a direct role in the regulation of blood flow (39).…”

Influence of hCG on inducible nitric oxide synthase gene expression in ram testicular arteries

“…Several reports could support this discrepancy. Firstly, hCG treatment is known to induce an increase in testicular blood flow, but this effect is not observed in Leydig cell-depleted animals, suggesting that the effect on blood flow is mediated by the increase in sex steroid secretion via stimulation of the Leydig cells (2). Secondly, studies have reported that hCG treatment results in local secretion within the testis of potent vasoconstrictors such as serotonin and endothelin-1 and that the increase in NO synthesis occurs to balance the effects of such local vasoconstrictors (25, 26).…”