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分析，采用PCR方法获得了催乳素基因的部分DNA，并对含有内含子2的DNA克隆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PRL的合成和分泌主要受下丘脑释放因子而非抑制因子控制。VIP被认为是这样一个因子，必须有特定的受体介导VIP的作用才能在细胞外和细胞内区域之间合成和释放PRL。prl产生细胞在垂体前叶头叶的定位，至少部分归因于VIP受体基因的定位表达。cAMP-PKA系统是鸡脑垂体头叶PRL基因表达的细胞内信使。3)泌乳素受体基因在乳发生中的表达。在小鼠乳腺中，泌乳素受体mRNA水平在妊娠前5天下降约60%，其低水平一直维持到妊娠第18天10:00。泌乳素受体mRNA水平在12 h内升高约6倍。在泌乳第0天维持高水平。催乳素受体mRNA的升高是由体内和体外皮质酮升高引起的。在去卵巢的孕中期小鼠乳腺中也发现了类似的变化。由此可见，催乳素受体基因在分娩前约12小时表达。

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.