电场刺激对离体温育垂体前叶促肾上腺皮质激素分泌的影响

EFFECT OF ELECTRICAL FIELD STIMULATION ON ADRENOCORTICOTROPIN RELEASE FROM INCUBATED ANTERIOR PITRITARY QUARTERS OF RAT

本实验应用离体温育大鼠垂体前叶组织块结合电场刺激及放射免疫测定方法，观察了垂体前叶内的神经纤维兴奋对促肾上腺皮质激素（ＡＣＴＨ）分泌的影响以及其它因素的作用。结果表明，一定参数的电场刺激使温育的大鼠四分之一垂体前叶组织块ＡＣＴＨ分泌增加，能被河豚毒素（ＴＴＸ）和藜芦碱部分阻断，此效应也可被地塞米松显著抑制，而同一参数的电场刺激与促肾上腺皮质激素释放激素（ＣＲＨ）诱发的ＡＣＴＨ分泌没有相互作用。经典神经递质受体阻断剂阿托品、心得安、酚妥拉明对电场刺激诱发的ＡＣＴＨ分泌没有显著影响；ＧＡＥＡ＿Ａ受体拮抗剂荷包牡丹碱明显促进此效应。该作用不受Ｐ物质拮抗剂ｓｐａｎｔｉｄｅ的影响，而降钙素基因相关肽（ＣＧＲＰ）受体拮抗剂ＣＧＲＰ片段８－３７能部分阻断这一作用。上述结果提示电场刺激所诱发的ＡＣＴＨ分泌可能部分由垂体前叶内ＣＧＲＰ能神经纤维介导。

The present study was undertaken to further investigate the action of the nerve fibers existingin the rat anterior pituitary on the secretion of adrenocorticotropin(ACTH).It was indicatedthat electrical field stimulation(EFS,30mA,0.5ms,10Hz)could increase the release of ACTHfrom the incubated anterior pituitary quarters of rat,and most of this effect was partly blockedby tetrodotoxin or veratridine added into the incubation medium,suggesting that the neuralcomponent in the gland might play a role in the above effect of EFS,The enhancing action of thenerve fibers on ACTH release did not interact on that ofcorticotropin releasing honnone(CRH),but was markedly suppressed by dexamethasone.Furthennore,GABA receptor antagonistbicuculline was found to potentiate the EFS-induced release of ACTH,while atropine,phentolamine and propranolol had no effect.Although SP antagonist(D-Argl,D-Trp7,9,D-Leu 11)-SP(spantide)could not alter the EFS-induced ACTH release from the anteriorpituitary fragments,CGRP receptor antagonist CGRP fragment(8-37)was found to reduce theeffect significantly,suggesting that the action of the CG RPergic nerve fibers in the anteriorpituitary may be involved in the regulation of ACTH secretion.