Studies of physiological action of neurohypophyseal hormone

精氨酸缩血管素（AVT）是鸟类的一种神经垂体激素。AVT具有抗利尿作用，可通过高渗刺激释放，但其释放机制尚不清楚。本研究旨在探讨AVT的释放机制，并比较禽类和哺乳动物AVT的释放机制。同时给予高渗盐水和阿片肽、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，则可进一步提高血浆AVT水平。从这些结果，我们可以认为，阿片肽可能通过高渗刺激调节AVT释放。侧脑室注射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。脑内注射AVT正义或随机寡核苷酸不能抑制高渗刺激引起的血浆AVT水平的升高。反义寡核苷酸可抑制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。这些数据也表明，反义寡核苷酸是有用的工具，在鸟类的神经内分泌学的研究。

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.