Basic study for application of stress-resistant effect of prolactin to animals

(1)低催乳素乳汁喂养对成年大鼠应激能力和母体行为的影响观察乳汁中催乳素对大鼠脑功能发育的影响。在妊娠第20天和第21天，将催乳素分泌抑制剂溴隐亭分别注射到小鼠的腹膜腔内，并在成年后对注射溴隐亭的母亲的应激耐受性和母性行为进行测试。与对照组相比，给溴隐亭母亲饲养的大鼠，无论是水束缚应激引起的胃溃疡程度还是对寄养幼鼠的母体行为潜伏期都显著增加。(2)大鼠催乳素受体基因第一外显子的鉴定及性激素对肝脏催乳素受体基因表达的调节第一外显子在肝脏中的表达分析表明，性类固醇激素特异性地调节了E1-2第一外显子的表达。(3)脑特异性调节大鼠催乳素受体基因表达的机制。脑特异性外显子1，E1-4定位于大鼠催乳素受体基因的外显子2和外显子3之间，对每个外显子在脑中的表达分析表明，在发育过程中催乳素基因表达的诱导依赖于E1-4的表达。

(1)Effects of rearing with low-prolactin milk on the stress-resistance and maternal behavior of rats at adulthoodEffects of milk-born prolactin on the development of brain function were examined in rats. Bromocriptin, a prolactin secretion inhibitor, was administrated into intraperitoneal cavity at days 20 and 21 of pregnancy, and stress-tolerance and maternal behavior reared by the bromocriptin-administrated mothers were tested at adulthood. Both the extent of gastric ulcer caused by water-restraint stress and latency of maternal behavior to foster pups were significantly increased in the rats reared by the bromocriptin-administrated mothers compared to those in rats reared by control mothers. These results suggest that milk-born prolactin plays an important role in establishment of neural networks for stress tolerance and maternal behavior.(2)Identification of a novel first exon of rat prolactin receptor gene and regulation of the prolactin receptor gene expression in the liver by sex steroid hormonesIn addition to the known four first exones, E1-1,E1-2,E1-3 and E1-4, another first exon, E1-5,was identified in the rat prolactin receptor gene. Analysis of expression of each first exon in the liver revealed that sex steroid hormones specifically regulate the expression of E1-2 first exon(3)Mechanism of brain-specific regulation of prolactin receptor gene expression in the ratThe brain-specific exon 1,E1-4,was found to localize between exons 2 and 3 of rat prolactin receptor gene, and analysis of expression of each first exon in the brain revealed that induction of prolactin gene expression during development depends on the expression of E1-4.