催乳素调节绵羊睾丸间质细胞睾酮分泌机制的研究

EFFECT OF PROLACTIN ON TESTOSTERONE SECRETION IN CULIURED OVINE LEYDIG CELL,WITH SPECIAL EMPHASIS ON THE MACHANISM

本实验利用睾丸间质细胞体外培养方法，研究了催乳素（ＰＲＳ）对睾酮分泌调节的机制。结果表明，体外培养的绵羊睾丸间质细胞对激素的刺激在培养的前四天较敏感。ｈＣＧ依剂量关系刺激睾酮的分泌。ＰＲＬ对于ｈＣＧ的刺激作用起着双相调节作用：低剂量的ＰＲＬ（１～３０ｎ／ｍｌ）可以增加ｈＣＧ的刺激强度３５～７１％，而高剂量的ＰＲＬ（１０００ｎｇ／ｍｌ）则抑制ｈＣＧ的活性４０％。当培养液中加入不同剂量的睾酮合成前体物（孕酮、雄烯二酮），ＰＲＬ可以调节前体物向睾酮的转化。低剂量的ＰＲＬ促进孕酮的转化，而高剂量的ＰＲＬ则抑制其转化。ＰＲＬ对雄烯二酮的转化则均呈现抑制性。用放射受体测定表明：低剂量ＰＲＬ（３～１０ｎｇ／ｍｌ）可以增加绵羊睾丸间质细胞膜上ＬＨ／ｈＣＧ受体的数量。但当ＰＲＬ剂量增加到３０～１０００ｎｇ／ｍｌ时，细胞膜上的ＬＨ／ｈＣＧ受体数量没有明显变化。这些结果表明：ＰＲＬ可以直接作用于绵羊性腺调节睾酮的分泌。这种调节作用是通过诱导细胞膜上ＬＨ／ｈＣＧ受体的数量和调节前体物转化为睾酮的某些步骤实现的。

A group of experiments was conducted to identify the effect and mechanism ofprolactin (PRL)on the testosterone secretion by cultured ovine Leydig cells. Tbe resultsshowed that the Leydig cell was sensitive to hCG stimulation within the first 4 day'sculture.The sensitivity declined following the repeated hCG treatment. PRL could modu-late the hCG stimulatory action on testosterone production,but in a biphasic pattern.PRL at low concentrations(1～10ng/ml) increased testosterone secretion from 35%to71%,whereas the higher dose of PRL(1000ng/ml)inhibited testosterone productionby 40%as compared to control. However, PRL alone showed no influence on testoster-one secretion.When different testosterone precursors (progesterone and androstenedione)were added,it revealed that PRL modulate the conversion of the precursors to testos-terone.The effect of PRL on the conversion of progesterone was biphasic,i.e.stimu-lative at low concentration and inhibitory at higher concentration,but inhibitoryconsistently on that of androstenedione.Radio-receptor assay indicated that the PRL atlow dose(3～10ng/ml)increased the number of LH/hCG receptors on the membrane ofLeydig cells,whereas no influence was observed when the PRL concentration was morethan 30ng/ml.These findings demonstrated that the augmenting effect of PRL on hCGinduced testosterone biosynthesis may be mediated by increase LH/hCG recoptor and onsome biochemical pathway.