Effects of the expression of bovine growth hormone on the testes and male accessory reproductive glands in transgenic mice

Abstract

The effects of physiological and excessive levels of growth hormone (GH) on reproductive functions are poorly understood, and impairment of fertility is frequently observed in transgenic animals overexpressing GH genes. The present study was undertaken to determine the effects of chronic exposure to heterologous bovine GH (bGH) on the testes and accessory reproductive glands in transgenic mice. Endocrine function of the testes was evaluated by measuring the activities of two steroidogenic enzymes, delta 5-3 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSD) and 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD). The activities of acid phosphatase, alkaline phosphatase and beta-glucuronidase, important hydrolytic enzymes of lysosomal origin, were measured in testes, seminal vesicles and ventral prostates in normal and transgenic mice. Testicular delta 5-3 beta-HSD activity was higher in transgenic than in normal mice, while testicular 17 beta-HSD activity in transgenic mice was not altered. Acid phosphatase activity was elevated in both seminal vesicles and ventral prostates of transgenic mice, while alkaline phosphatase activity was increased only in the prostate. The activity of beta-glucuronidase was elevated in the testes, seminal vesicles and ventral prostate gland of transgenic mice. These results suggest that chronic exposure to bGH is associated with significant stimulation of some hydrolytic enzymes in the testes and in the accessory reproductive glands of transgenic mice.