大鼠垂体细胞液泡内存在黄体生成激素（LH）

研究者普遍认为糖蛋白激素存在于促性腺激素（gonadotrophin,GTH)细胞的颗粒内,目前在生殖内分泌领域内对糖蛋白激素形成与释放的研究也主要集中在细胞内颗粒的变化上,我们近年的研究发现,大鼠垂体GTH细胞内黄体生成激素（luteinizing hormone,LH)的分泌与细胞内液泡的形态变化有密切的关系。铁形态也随液泡的形态变化而变化,因而推测“LH的储存与释放可能与液泡有极大的关系”,为进一步揭示垂体细胞的液泡内是否存在LH和探讨哺乳动物垂体细胞的液泡是否具有储存与释放LH的功能,本研究对大鼠垂体细胞的液泡进行了分离和纯化。用SDS－PAGE,Western immunobloting及Con A/HRP等方法分别对纯化的垂体,大脑皮层及肝脏组织的液泡进行了蛋白质,LH及糖蛋白的分析。结果显示：（1）垂体,皮层及肝脏细胞的液泡内均含有丰富的,分子量大小不等的蛋白质成分,不同组织的细胞液泡内蛋白质成分有许多是相似的;（2）垂体组织及其液泡内均含有LH,而且在相同浓度的蛋白量中,两者LH的水平并无明显差异;（3）垂体,皮层和肝脏组织液泡内均有分子量不同的糖蛋白,但只有垂体细胞的液泡内才有与LH位置相同的糖蛋白染色谱带。上述结果表明：虽然哺乳动物不同组织的细胞液泡内含有许多相似的蛋白质成分,但LH是特异性地存在于垂体细胞液泡内。在这些LH分子中,至少有一部分是已经装配了糖基的完整LH分子。因此,垂体细胞的液泡有可能具有储存与释放LH的功能。

Identification of the existence of luteinizing hormone in pituitary vacuoles of rats

It is generally believed that glycoprotein hormone exists in granules of the gonadotrophin (GTH) cells, and recent studies on the formation and secretion of glycoprotein hormones also concern much on the changes in the pituitary granules. In our previous studies, it was found that the secretion of luteinizing hormone (LH) was closely related to the morphological changes in pituitary vacuoles of rats, and the morphology of GTH cells was also closely related to the changes in vacuolar morphology. Therefore, it appears that there exists an inseparable relationship between the storage and secretion of LH and pituitary vacuoles. In order to examine whether the pituitary vacuoles contain LH in rats, and to further explore if LH is stored and released by the pituitary vacuoles, the vacuoles were separated and purified from pituitary, cortex and liver tissues by density gradient centrifugation. The vacuolar protein components, LH and glycoproteins were determined by the methods of SDS-PAGE, Western immunoblot and Con A/HRP, respectively. The results showed that (1) abundant protein components with various molecular masses were present in the vacuoles of the pituitary, cortex and liver in male, female and ovariectomized rats, and some of the protein components were similar in the molecular mass; (2) both pituitary tissues and vacuoles contained LH, and their LH levels had no significant difference by quantitative analysis of extracted protein samples; and (3) glycoproteins of various molecular masses were found in the vacuoles of the pituitary, cortex and liver, but the same position of stained glycoprotein band and LH molecular mass was only observed in the pituitary vacuoles. From the results given above, it can be concluded that LH specifically exists in the pituitary vacuoles, although there are some similar protein components in various cellular vacuoles. The possibility was further demonstrated at the molecular level that the pituitary vacuoles may have the function of storing and releasing LH due to the pituitary vacuoles containing LH with assembled glycone.