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

(1)低催乳素乳喂养对大鼠成年期应激抵抗和母性行为的影响。在妊娠第20天和第21天分别腹腔注射催乳素抑制剂溴隐亭，成年后对服用溴隐亭的母亲进行应激耐受性和母性行为的检测。与对照母鼠相比，服用溴隐亭母鼠饲养的大鼠由限水应激引起的胃溃疡程度和母鼠育仔行为潜伏期均显著增加。这些结果表明，母乳泌乳素在应激耐受和母性行为的神经网络建立中起重要作用。(2)大鼠催乳素受体基因第一外显子的新发现及性类固醇激素对肝脏催乳素受体基因表达的调控除已知的4个第一外显子E1-1、E1-2、E1-3和E1-4外显子外，还在大鼠催乳素受体基因中发现了另一个第一外显子E1-5。对肝脏各第一外显子的表达分析表明，性类固醇激素特异性调控e2 -2第一外显子的表达。(3)大鼠脑特异性调控催乳素受体基因表达的机制，发现脑特异性外显子1 E1-4位于大鼠催乳素受体基因的2、3外显子之间。对大脑中每个第一外显子的表达分析表明，发育过程中催乳素基因表达的诱导取决于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.