Hypothalamic, pituitary and testicular function during sexual maturation of the male rat.
Hypothalamic, pituitary and testicular function during sexual maturation of the male rat.
复制标题
雄性大鼠性成熟过程中的下丘脑、垂体和睾丸功能。
作者：
A. Payne;R. Kelch;E. Murono;J. T. Kerlan
从出生到第64天以及第74天和第89天，以大约5天的间隔测量各组大鼠下丘脑促性腺激素释放激素（GnRH）含量、血清LH和FSH、睾丸体外合成睾酮的能力以及睾丸5-烯-3 β-羟基类固醇脱氢酶异构酶和17 β-羟基类固醇脱氢酶。在存在饱和剂量的大鼠LH的情况下，测定睾丸体外合成睾酮的能力。促性腺激素释放激素从出生时的0-17 ng/下丘脑稳定增加到第52天的最大值7 ng，然后保持恒定。LH浓度变化很大，在第10天和第32天之间经常超过成人值。在第32天后，观察到稳定上升，在第37天和第42天之间达到成年值。FSH浓度从出生时和第10天观察到的255 ng/ml显著增加至第32天的峰值1000 ng/ml。随后，FSH值稳步下降，直至第74天浓度恢复至出生时的值。5-烯-3 β-羟基类固醇脱氢酶-异构酶活性在第12天至第19天之间表现出快速增加，随后在第19天至第32天达到成虫水平时，增加速率甚至更大。17 β-羟基类固醇脱氢酶活性在出生至第22天之间非常低。酶活性在第22天开始增加，在第37天和第58天之间观察到活性的快速增加。睾酮合成能力的增加紧随着17 β-羟基类固醇脱氢酶活性的增加。该研究表明，在雄性大鼠性成熟期间，血清LH和FSH的变化并不反映下丘脑GnRH的变化。通过5-烯-3 β-羟基类固醇脱氢酶-异构酶活性监测，Leydig细胞的出现先于睾丸体外合成睾酮能力增加约20天。后者与17 β-羟基类固醇脱氢酶活性的增加相一致。这些结果表明，17 β-羟基类固醇脱氢酶是睾丸对LH刺激反应能力的限制因素。
Hypothalamic content of gonadotrophin-releasing hormone (GnRH), serum LH and FSH, capacity of the testis to synthesize testosterone in vitro, and testicular 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase and 17 beta-hydroxysteroid dehydrogenase were measured in groups of rats at approximately 5 day intervals from birth to day 64 and at days 74 and 89. The capacity of the testes to synthesize testosterone in vitro was measured in the presence of a saturating dose of rat LH. Gonadotrophin-releasing hormone increased steadily from 0-17 ng per hypothalamus at birth to a maximum of 7 ng at day 52 and then remained constant. LH concentrations were highly variable and often exceeded adult values between days 10 and 32. After day 32 a steady rise was observed which reached adult values between days 37 and 42. FSH concentrations markedly increased from 255 ng/ml observed at birth and day 10 to a peak value of 1000 ng/ml at day 32. Subsequently there was a steady decline in FSH values until day 74 when the concentration returned to values found at birth. 5-ene-3 beta-Hydroxysteroid dehydrogenase-isomerase activity exhibited a rapid increase between days 12 and 19 followed by an even greater rate of increase between days 19 and 32 when adult levels were attained. 17 beta-Hydroxysteroid dehydrogenase activity was very low between birth and day 22. Enzyme activity began to increase at day 22 with a rapid increase in activity observed between days 37 and 58. The increase in capacity to synthesize testosterone closely followed the increase in 17 beta-hydroxysteroid dehydrogenase activity. The study demonstrates that during sexual maturation in the male rat, changes in serum LH and FSH do not reflect changes in hypothalamic GnRH. The appearance of Leydig cells as monitored by 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase activity precedes by approximately 20 days the increase in testicular capacity to synthesize testosterone in vitro. The latter coincides with the increase in 17 beta-hydroxysteroid dehydrogenase activity. These results suggest that 17 beta-hydroxysteroid dehydrogenase is a limiting factor in the ability of the testis to respond to LH stimulation.