Inhibitory effects of acute gonadotrophin stimulation on the reproductive system of male rats

Chronic administration of a gonadotropin-releasing hormone (GnRH) agonist affects testicular microvasculature

“…One may specu¬ late that GnRH-A can cause degeneration of tes¬ ticular blood vessels. Although not described in previous studies, vascular degeneration is very likely to occur concomitantly with the focal testicu¬ lar necrosis after GnRH-A administration as found by several authors (Habenicht et al 1985(Habenicht et al , 1987Sandow et al 1985). In the present study, we have found no signs of early degeneration (necrosis of endothelial cells), but rather superfluous basal lamina-like structures.…”

“…After 16 weeks of daily treatment, the semi¬ niferous tubules contained only type A and spermatogonia, a few spermatocytes, and Sertoli cells with increased numbers of phagosomes and lipid droplets. These alterations as well as the accumula¬ tion of lipid droplets and the presence of mito¬ chondria with lamellar cristae in the Leydig cells were reversible within 16 weeks after cessation of the treatment.There is increasing evidence that GnRH-A has additional effects on the testicular microvasculature: in the rat severe vasodilatation, hyperemia, accumulation of leucocytes and interstitial edema have been reported by Habenicht et al (1985Habenicht et al ( , 1987 and Sandow (1985) to occur within a few hours after a single injection with a GnRH-A. Similar ef¬ fects were described by Habenicht & Müller (1988) in another species, the golden hamster.…”

“…There is increasing evidence that GnRH-A has additional effects on the testicular microvasculature: in the rat severe vasodilatation, hyperemia, accumulation of leucocytes and interstitial edema have been reported by Habenicht et al (1985Habenicht et al ( , 1987 and Sandow (1985) to occur within a few hours after a single injection with a GnRH-A. Similar ef¬ fects were described by Habenicht & Müller (1988) in another species, the golden hamster.…”

“…The increase is likely to be due to the rise of LH after GnRH-A injection. A single sc injection of GnRH-A has acute vascular effects in the rat testis (vasodilatation, hyperemia, accumulation of leuco¬ cytes and interstitial edema), followed by focal tes¬ ticular necrosis within 24 h, which could be anta¬ gonized by the cyclooxygenase inhibitor (prostaglandin synthesis inhibitor) indomethacin (Habe¬ nicht et al 1985(Habe¬ nicht et al , 1987Sandow et al 1985). Habe¬ nicht 8c Müller (1988) demonstrated that the vascu¬ lar effects are neither specific for the rat nor for the testis.…”

Reduction of testicular blood flow and focal degeneration of tissue in the rat after administration of human chorionic gonadotrophin

“…However, since the present study indicates that Leydig cells are the mediators in the reduction of blood flow, the action of LHRH may be effected through Leydig cells either directly or indirectly via pituitary LH. Indications of damaged testicular tissue were also reported by Sandow, von Reichenberg, Engelbart et al (1985) 24 h after hCG treatment, and in hypophysectomized rats by Kerr & Sharpe (1986) after daily treatment with LH alone or in combination with an LHRH agonist. These data and those of the present study show that a hormone-induced transient reduction in blood flow can be so severe that focal degeneration of testicular cells can occur.…”