Studies of physiological action of neurohypophyseal hormone

精氨酸催产素（AVT）是鸟类的神经垂体激素之一。众所周知，AVT具有抗利尿作用，并在高渗刺激下释放，但有关AVT释放机制的信息很少。本研究的目的是探讨AVT的释放机制，并比较鸟类和哺乳动物之间的机制。当鸡接受高渗盐水时，血浆AVT水平显着升高。当鸡同时给予高渗盐水和阿片肽、吗啡时，血浆AVT水平的升高受到抑制。另一方面，当鸡同时给予高渗盐水和阿片肽拮抗剂纳洛酮时，血浆AVT水平的升高进一步增强。从这些结果中，我们可以表明阿片肽可能通过高渗刺激来调节 AVT 释放。然而，排卵时AVT的释放不受阿片拮抗剂或激动剂的影响。脑室内注射AVT反义寡核苷酸可抑制高渗刺激引起的血浆AVT水平的升高。小脑内注射 AVT 有义或随机寡核苷酸不会抑制高渗刺激引起的血浆 AVT 水平的增加。反义寡核苷酸可以抑制 AVT 合成机制中 AVT mRNA 翻译成氨基酸。因此，这些数据可能支持AVT生物合成机制涉及AVT从神经垂体释放的机制。此外，这些数据表明反义寡核苷酸是研究鸟类神经内分泌学的有用工具。

Arginine vasotocin (AVT) is one of neurohypophyseal hormone in the birds. It is well known that AVT has an antidiuretic action and is released by hypertonic stimulation, but it is little information about the release mechanism of AVT.The aim of this study investigates the release mechanisms of AVT and compares the mechanism between birds and mammals.When the chickens were received hypertonic saline, the plasma levels of AVT significantly increased. When chickens were received simultaneously with hypertonic saline and opioid peptide, morphine, the increase of plasma levels of AVT was inhibited. On the other hands, when the chickens were received simultaneously with hypertonic saline and opioid peptide antagonist, naloxone, the increase of plasma levels of AVT was further enhanced. From these results, we can suggest that opioid peptide may regulate AVT release by hypertonic stimulation. However, AVT release at oviposiiton were not effected by opioid antagonist or agonist.The intracerebroventricular injection of AVT antisense oligonucleotide inhibited the increase of plasma levels of AVT by hypertonic stimulation. The intracerevelo injection of AVT sense or random oligonucleotide did not inhibit the increase of plasma levels of AVT by hypertonic stimulation. Antisense oligonucleotide may inhibit translation to amino acid from AVT mRNA within the AVT synthesis mechanism. Therefore, these data may support that AVT biosynthesis mechanism involves the mechanism of AVT release from the neurohypophysis. Also, these data suggest that antisense oligonucleotide is useful tool for the study of neuroendocrinology in birds.