Studies of physiological action of neurohypophyseal hormone

精氨酸催产素（AVT）是鸟类神经垂体激素的一种。众所周知，AVT具有抗利尿作用，并在高渗刺激下释放，但对AVT的释放机制了解甚少。本研究旨在探讨AVT的释放机制，并比较鸟类和哺乳动物AVT的释放机制。经高渗生理盐水处理后，血浆AVT水平显著升高。同时给予高渗生理盐水和阿片肽、吗啡可抑制AVT血浆水平的升高。另一方面，当高渗生理盐水和阿片肽拮抗剂纳洛酮同时给药时，AVT血浆水平的升高进一步增强。由此可见，阿片肽可能通过高渗刺激调节AVT的释放。然而，AVT在排卵时释放不受阿片拮抗剂和激动剂的影响。脑室内注射AVT反义寡核苷酸抑制高渗刺激引起的血浆AVT水平升高。脑内注射AVT感觉或随机寡核苷酸均未抑制高渗刺激引起的血浆AVT水平升高。反义寡核苷酸可能在AVT合成机制中抑制AVT mRNA向氨基酸的翻译。因此，这些数据可能支持AVT的生物合成机制涉及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.