Prolactin and Leydig cell steroidogenic enzymes in the bonnet monkey (Macaca radiata)

Abstract

The effect of treatment with prolactin or bromocryptine on testicular steroidogenesis and serum hormone levels were studied in immature and mature bonnet monkeys. Leydig cells alone showed the presence of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) in normal immature and mature monkeys. Administration of prolactin increased the activity of 3 beta-HSD and 17 beta-HSD in Leydig cells from mature monkeys, and also increased the serum levels of testosterone. Bromocryptine treatment induced exactly the opposite effect. These changes occurred in the absence of any change in serum gonadotrophin levels. In immature monkeys, prolactin and bromocryptine had no significant effect. These results suggest a direct stimulatory effect of prolactin on testicular steroidogenesis in mature monkeys.

Regulation of Yolk-Androgen Concentrations by Plasma Prolactin in the American Kestrel

“…17␤-Hydroxysteroid dehydrogenase (17␤-HSD) reversibly converts A 4 and T, and aromatase irreversibly converts A 4 to estrone and T to estradiol. It is possible that prolactin inhibits the activity of aromatase, as observed in the ovaries of rats (Dorrington and GoreLangton, 1981;Tsai-Morris, Ghosh, Hirshfield, Wise, and Brodie, 1983;Papadopoulos, Drosdowsky, and Carreau, 1986) and enhances the activity of both 3␤-HSD and 17␤-HSD, as observed in the testis of the bonnet monkey, Macaca radiata (Gunasekar, Kumaran, and Govindarajulu, 1988). If ovarian A 4 is abundant and its conversion to T limited by 17␤-HSD activity, as might be suggested by the much higher yolk concentrations of A 4 compared to T, then enhancement of 17␤-HSD combined with inhibition of aromatase might lead to a net accumulation of T, possibly also within the yolk (Zelinski-Wooten, Hess, Baughman, Molskness, Wolf, and Stouffer, 1993).…”

Effects of metachlopromide-induced hyperprolactinemia on serum testosterone and its response to hCG in adult male common marmosets (Callithrix jacchus)

“…It is interesting that even at this stage, the testicular response to hCG challenge was completely normal indicating lack of direct effect of metachlopromide induced hyperprolactinemia on testicular function and rather suggests effect on hypothalamo-pituitary function. GUNASEKAR et al (1988) reported direct stimulatory effects of prolactin treatment for ten days on testicular functions of adult bonnet monkeys. However, RAO et al (1990) in the same species observed that single injection of chlorpromazine-induced hyperprolactinemia abolished the nocturnal testosterone rhythm.…”

“…GUNASEKAR et al (1988) reported that administration of ovine prolactin for ten days to adult male bonnet monkeys (Macaca radiata) increased the activity of 3/3-HSD and 17/3-HSD in leydigs cells and also increased the serum levels of testosterone. These changes occurred in the absence of any effect on serum gonadotropin levels suggesting a direct stimulatory effect of prolactin on testicular steroidogenesis.…”

Corticosterone impairs the mRNA expression and activity of 3β- and 17β-hydroxysteroid dehydrogenases in adult rat Leydig cells

“…Apart from LH, prolactin and insulin also modulate the functions of Leydig cells (Blanco et al 1981;Gunasekar et al 1988). Prolactin increases the number of LH receptors on Leydig cells and potentiates the action of LH on testosterone production.…”