Studies of physiological action of neurohypophyseal hormone

精氨酸催产素(AVT)是鸟类体内的一种神经垂体激素。众所周知，AVT具有抗利尿作用，是通过高渗刺激释放的，但对AVT的释放机制知之甚少。本研究的目的是研究AVT的释放机制，并比较鸟类和哺乳动物的释放机制。同时给予鸡高渗盐水和阿片肽、吗啡，可抑制血浆AVT水平的升高。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。这些结果提示，阿片肽可能通过高渗刺激调节AVT的释放。但阿片类拮抗剂或激动剂不影响产卵时AVT的释放，侧脑室注射AVT反义寡核苷酸可抑制高张刺激引起的血浆AVT水平的升高。脑内注射AVT正义或随机寡核苷酸不能抑制高张刺激引起的血浆AVT水平的升高。反义寡核苷酸可能在AVT合成机制中抑制AVT基因向氨基酸的翻译。因此，这些数据可能支持AVT的生物合成机制涉及到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.