催乳素对培养的绵羊睾丸间质细胞睾酮分泌的影响

在绵羊睾丸间质细胞体外无血清长期培养的条件下,研究了催乳素对睾丸间质细胞睾酮分泌的调节作用。实验结果表明,催乳素可增强细胞对人绒毛膜促性腺激素(hCG)刺激的反应。催乳素的这种作用呈双相调节。睾酮分泌量显著高于hCG和催乳素单独作用时的总和。在hCG存在下,不同的底物转化为睾酮的量不同。其中雄烯二酮和孕酮转化为睾酮的方式存在着双相性。脱氢表雄酮转为睾酮的量少,不存在双相性,而与其剂量成正比。催乳素在hCG存在下可调节底物转化为睾酮。低剂量的催乳素(1ng/ml)可使一定剂量的孕酮(10～30ng/ml)转化为睾酮的量明显增加,而高剂量的催乳素(>10ng/ml)却明显地抑制孕酮转化为睾酮。催乳素可明显地抑制雄烯二酮转化为睾酮,与剂量无关。可见催乳素对于孕酮和雄烯二酮这两个关键底物转化为睾酮的调节是不同的。催乳素增强hCG刺激睾酮分泌的作用可能部分是通过其促进孕酮转化为睾酮来实现的。

EFFECT OF PROLACTIN ON TESTOSTERONE SECRETION IN CULTURED OVINE LEYDIG CELLS

The present experiment was conducted to study the regulating effect of prolactin (PRL) on the secretion of testosterone in cultured ovine Leydig cells without serum. The results showed that PRL enhanced the stimulating effect of human chorionic gonadotrophin (hCG) on testosterone production, but in a biphasic pattern. The level of testosterone secretion by the cells stimulated by PRL and hCG was significantly higher than the sum of that stimulated by PRL or hCG alone. In the presence of hCG, the amount of testosterone secretion varied with different precursors. Androstenedione and progesterone could convert into more testosterone than dehydroeplandrosterone could, but in a biphasic way, while the amount of testosterone converted from dehydroeplandrosterone was directly proportional to the dose of the latter. PRL could modulate the conversion of the precursor into testosterone in the presence of hCG. Low concentration (Ing/ml) of PRL stimulated conversion of progesterone into testosterone, and high concentration (10, 100ng/ml) inhibited it significantly, while conversion of androstenedione into testosterone was inhibited by PRL consittently, indicating that the modulating effect of PRL on the two key precursors was different. The results suggest that PRL enhances the stimulating effect of hCG on the secretion of testosterone partially via stimulating the conversion of progesterone into testosterone.