甘丙肽（galanin）对大鼠垂体前叶催乳素和β－内啡肽释放的调节

REGULATORY ROLE OF GALANIN ON PROLACTIN AND β-ENDORPHIN RELEASE FROM ANTERIOR PITUITARY LOBE OF RAT

本工作探讨甘丙肽是否参与垂体前叶催乳素和β－内啡肽释放的调节。实验分两部分：（１）在体实验，给清醒自由活动的大鼠第三脑室内微量注射甘丙肽（１μｇ或３μｇ／只），用放射免疫测定法检测血浆催乳素和β－内啡肽的浓度。结果如下：每只大鼠给１μｇ或３μｇ的甘丙肽后，都显著兴奋催乳素的静息分泌，３μｇ甘丙肽对催乳素分泌的兴奋效应显著大于１μｇ的作用。两种剂量的甘丙肽都不影响限制性应激引起的催乳素的释放；对β－内啡肽的静息分泌和应激引起的释放也无明显影响。（２）离体实验，在体外培养的垂体前叶细胞中，加入不同剂量的甘丙肽（０．０５，０．５和１．０μｇ），孵育１ｈ后，用上述方法测定培养液中催乳素和β－内啡肽的浓度。其结果是三种剂量的甘丙肽都显著兴奋β－内啡肽的分泌，兴奋效应随甘丙肽的剂量增加而增大，有显著的剂量效应；但三种剂量的甘丙肽对催乳素的分泌均无作用。以上结果表明，甘丙肽对垂体前叶催乳素和β－内啡肽释放的调节作用不同。中枢的甘丙肽可能通过一定的下丘脑机制兴奋垂体前叶催乳素的静息分泌，但不影响应激引起的催乳素的释放，也不影响β－内啡肽的静息分泌和应激引起的释放。外周的甘丙肽虽然对垂体前叶细胞的催乳素分泌无直接作用，但兴奋?

The role of brain-gut peptide galanin in the regulation of prolactin (PRL) and β-endorphin (β-EP) release from anterior pituitary lobe was studied in vivo in consciousmale rats and in vitro with cultured anterior pituitary cells of the rat. Galanin (1 μg or3 μg/rat) injected into the third cerebral ventricle of rats produced highly significant,dose-related increases of PRL resting secretion, but did not alter resting secretion of β-EP and restraint stress-induced release of PRL and β-EP. However, galanin (0. 05,0. 5 and 1. 0 μg/5 × 105 cells· ml-1 ) induced highly significant, dose-related increaseof β-EP secretion from dispersed anterior pituitary cells, but failed to alter significantlyPRL secretion from the cultured cells. These results indicate that central galanin has astimulatory role in pituitary PRL resting secretion via the hypothalamus, whereas peripheral galanin stimulates β-EP secretion only via direct action of this peptide in anterior pituitary cells.