Establishment of assay system for prolactin by gene targetting

1)小鼠催乳素基因的克隆及核苷酸序列分析为了研究催乳素基因的结构，我们用PCR方法获得了催乳素基因的部分DNA，并对该DNA克隆的内含子2进行了核苷酸序列分析。2）催乳素基因表达的VIP受体与哺乳动物不同，鸟类催乳素的合成和分泌主要受下丘脑释放因子而不是抑制因子的控制。VIP被认为是这样一种因子，并且特异性受体必须介导VIP在细胞外和细胞内区域之间的PRL合成和释放的作用。垂体前叶垂体前叶PRL分泌细胞的定位至少部分归因于VIP受体基因的定位表达。cAMP-PKA系统是鸡垂体头叶PRL基因表达的细胞内信使。3）催乳素受体基因在泌乳期的表达：在小鼠乳腺中，催乳素受体mRNA的表达水平在妊娠前5天下降约60%，并一直维持到妊娠第18天的10：00。催乳素受体mRNA的水平增加约6倍，在接下来的12小时内。高水平在泌乳的第0天被消除。催乳素受体mRNA的增加是由体内和体外皮质酮的增加引起的。在去卵巢的中孕小鼠乳腺中也发现了类似的变化。结论：催乳素受体基因在分娩前12 h左右表达。

1) Cloning and nucleotide sequence analysis of mouse prolactin gene.To investigate the structural analysis of Prolactin gene, a partial DNA of prolactin gene was obtained by PCR and the nucleotide sequence of this DNA clone contained intron 2 was analyzed.2) VIP receptor for prolactin gene expression.Unlike mammals, synthesis and secretion of PRL in birds is controlled predominantly by the hypothalamic releasing factor rather than inhibiting factor. VIP is proposed to be such a factor and specific receptor must mediate VIP actions for PRL synthesis and release between extracellular and intracellular regions. Localization of PRL-producing cell in the cephalic lobe of anterior pituitary gland is attributable, at least in part, to localized expression of VIP receptor gene. The cAMP-PKA system is an intracellular messenger for PRL gene expression in the cephalic lobe of the pituitary gland in the chicken.3) Prolactin receptor gene expression at lactogenesis.In the mouse mammary gland, the level of prolactin receptor mRNA decreased about 60% during the first 5 days of pregnancy, and its low levels were maintained until 10 : 00 on day 18 of pregnancy. The level of prolactin receptor mRNA increased about 6 folds during the next 12 h period. The high level was maintaind on day zero of lactation. The increase in the prolactin receptor mRNA was caused by the increase in corticosterone in vivo and in vitro. The similar changes were found in the ovariectomized midpregnant mouse mammary gland. It is concluded that the prolactin receptor gene expresses about 12 h before the onset of parturition.