Uemura H, Naruse M, Nakamura S, Naruse K, Yamamoto T, Demura H, Hirohama T
Biological Laboratory, Kanagawa Dental College, Yokosuka, Japan.
Endocr J. 1994 Dec;41(6):685-91. doi: 10.1507/endocrj.41.685.
Previously we found intragranular colocalization of immunoreactive endothelin-1 and neurohypophysial hormones in the axon terminals of the rat neural lobe. To investigate the function of endothelin-1 in the rat neural lobe, immunoreactive endothelin-1 in plasma and the neural lobe was measured by enzyme immunoassay in rats subjected to hemorrhage and in other rats who were deprived of water for 2 days to induce dehydration. Changes in plasma arginine vasopressin were determined by radioimmunoassay. In addition, morphometric analysis was performed in the neural lobe of rats exposed to these stresses. Plasma concentrations of immunoreactive endothelin-1 were unchanged following hemorrhage or dehydration, whereas those of immunoreactive vasopressin were remarkably increased. In the neural lobe, immunoreactive endothelin-1 content and the number of neurosecretory granules decreased significantly after dehydration. However, immunoreactive endothelin-1 in tissue increased nearly three-fold in hemorrhaged rats, whereas the endothelin-1-immunolabeling in the axon terminals was unchanged. These results suggest that endothelin-1 in the hypothalamo-hypophysial system may be involved in the local modulation of vasopressin secretion when an animal is exposed to hypovolemic and/or osmotic stress.
此前我们发现，在大鼠神经垂体的轴突终末中，免疫反应性内皮素-1与神经垂体激素存在颗粒内共定位。为了研究内皮素-1在大鼠神经垂体中的功能，我们采用酶联免疫吸附测定法，检测了遭受出血的大鼠以及另外连续2天禁水以诱导脱水的大鼠血浆和神经垂体中免疫反应性内皮素-1的水平。通过放射免疫测定法测定血浆精氨酸加压素的变化。此外，对遭受这些应激的大鼠神经垂体进行了形态计量分析。出血或脱水后，血浆中免疫反应性内皮素-1的浓度未发生变化，而免疫反应性加压素的浓度显著升高。在神经垂体中，脱水后免疫反应性内皮素-1的含量和神经分泌颗粒的数量显著减少。然而，出血大鼠组织中的免疫反应性内皮素-1增加了近三倍，而轴突终末中的内皮素-1免疫标记未发生变化。这些结果表明，当下丘脑-垂体系统中的动物暴露于低血容量和/或渗透压应激时，内皮素-1可能参与血管加压素分泌的局部调节。
