Buckingham J C, Wilson C A
J Endocrinol. 1985 Feb;104(2):173-7. doi: 10.1677/joe.0.1040173.
Administration of pregnant mare serum gonadotrophin (PMSG) to peripubertal rats, aged 27 days, induces ovulation provided the animals weigh more than 60 g at the time of the injection. In an attempt to determine whether the apparent immaturity of the ovaries in smaller rats is associated with an inability of the pituitary gland to secrete LH, the biological and immunological properties of LH in peripubertal PMSG-treated rats were examined. A single injection of PMSG caused a marked hypersecretion of LH in rats aged 27 days. The LH in the plasma of rats weighing more than 60 g was active in both the radioimmunoassay and the cytochemical bioassay but that in smaller rats was active only in the former. Plasma from both groups of rats stimulated the release of testosterone from dispersed Leydig cells. Luteinizing hormone-releasing hormone stimulated the secretion, in vitro, of immunoreactive, cytochemically active LH by pituitary tissue from rats weighing over 60 g. The LH released in vitro from tissue from the smaller animals, like that in their plasma, was active in the radioimmunoassay but not in the cytochemical system. The results suggest that an abrupt change in the nature of LH occurs at puberty and that ovulatory cycles commence only when the pituitary gland secretes the adult form of LH with a full spectrum of biological activity.
给27日龄的青春期前大鼠注射孕马血清促性腺激素（PMSG）可诱导排卵，前提是注射时动物体重超过60克。为了确定较小大鼠卵巢明显不成熟是否与垂体分泌促黄体生成素（LH）的能力不足有关，研究了青春期前经PMSG处理的大鼠体内LH的生物学和免疫学特性。单次注射PMSG会导致27日龄大鼠的LH显著分泌过多。体重超过60克的大鼠血浆中的LH在放射免疫测定和细胞化学生物测定中均有活性，但较小大鼠血浆中的LH仅在前者中有活性。两组大鼠的血浆均刺激了分散的睾丸间质细胞释放睾酮。促黄体生成素释放激素在体外刺激体重超过60克的大鼠垂体组织分泌免疫反应性、细胞化学活性的LH。较小动物组织在体外释放的LH，与它们血浆中的LH一样，在放射免疫测定中有活性，但在细胞化学系统中无活性。结果表明，LH的性质在青春期会发生突然变化，并且只有当垂体分泌具有全谱生物活性的成年形式的LH时，排卵周期才会开始。
