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Regulation of testicular function in boars of divergent genotypes

By Eraldo Lourenso Zanella


The objective of the first experiment was to determine the effect of SB75, a potent GnRH antagonist, on secretion of gonadotropins and steroid hormones in Meishan (MS) and White Composite (WC) boars. MS boars have greater concentrations of FSH, LH and testosterone compared to WC boars. Concentrations of FSH, LH and testosterone decreased after treatment with SB75, and the magnitude of these responses was greater in MS than in WC boars. The prolonged inhibitory effect of SB75 in suppression of concentrations of testosterone in blood plasma in the presence of pretreatment of LH implied a direct effect of SB75 at the testis. In the second experiment boars were castrated and testicular tissue was incubated in the presence of SB75 or with a GnRH agonist, Deslorelin. SB75 had a direct effect on the testis decreasing amounts of testosterone and estrone released from Leydig cells; however, treatment with Deslorelin had no direct effect on release of these gonadal steroids. In the second study discussed herein, the objective was to evaluate morphological characteristics and testicular function of half-sib boars with different endogenous concentrations of FSH. Boars with low FSH had larger testicular and epididymal wt than boars with high FSH, and greater daily sperm production per g of testis. Testes of boars with low FSH had a greater percentage of seminiferous tubules, a lesser percentage of Leydig cells and a somewhat lesser percentage of vascular structures than testes of boars with high FSH. Testes of boars with low FSH had greater total tubule volume and tubule length than testes of boars with high FSH. Total volume of Leydig cells, total number of Leydig cells, and production of testosterone in vitro per paired testis or per million Leydig cells were not different among these boars with high FSH or low FSH. Greater concentrations of FSH in blood plasma were negatively associated with the development of seminiferous tubules and spermatogenic efficiency; whereas Leydig cell development was not different in these two groups of boars

Topics: Anatomy & physiology|Animals
Publisher: DigitalCommons@University of Nebraska - Lincoln
Year: 1998
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