Huang Y P, Peng C, Peter R E
Department of Zoology, University of Alberta, Edmonton, Canada.
Gen Comp Endocrinol. 1991 Oct;84(1):67-75. doi: 10.1016/0016-6480(91)90065-e.
The metabolic clearance rate (MCR) and initial half-disappearance time (T(1/2)i) of salmon gonadotropin-releasing hormone (sGnRH) and its agonist analog [D-Arg6,Pro9-NEt]-sGnRH (sGnRH-A) were investigated in goldfish, following a single intraarterial injection of radioiodinated sGnRH and sGnRH-A. The tissue uptake of radioiodinated sGnRH-A was also investigated. 125I-sGnRH had a MCR of 0.01173 ml min-1 35 g-1 and a (T(1/2)i) of 32.38 min; 125I-sGnRH-A had a MCR of 0.0192 ml min-1 35 g-1 and a (T(1/2)i) of 72.95 min. In the tissue uptake experiments, high levels of accumulated labeled sGnRH-A were generally found in the gills, kidney, liver, and pituitary compared to air bladder, brain, gonad, eyes, and muscle. Coinjection of excess amount of cold sGnRH-A caused decreased uptake of labeled sGnRH-A only in pituitary, but increased accumulation of labeled sGnRH-A in some other tissues. Our results show a correlation between the T(1/2)i and the affinity of the peptides for a serum GnRH binding protein present in the goldfish, suggesting that the formation of a hormone-binding protein complex may decrease the MCR of GnRH in the circulation in goldfish. Our data also indicate specific uptake of 125I-sGnRH-A by the pituitaries of both male and female goldfish, confirming the pituitary as a major target organ of GnRH in goldfish.
在金鱼体内，经动脉单次注射放射性碘化鲑鱼促性腺激素释放激素（sGnRH）及其激动剂类似物[D-Arg6,Pro9-NEt]-sGnRH（sGnRH-A）后，对其代谢清除率（MCR）和初始半衰期（T(1/2)i）进行了研究。同时还研究了放射性碘化sGnRH-A的组织摄取情况。125I-sGnRH的MCR为0.01173 ml min-1 35 g-1，T(1/2)i为32.38分钟；125I-sGnRH-A的MCR为0.0192 ml min-1 35 g-1，T(1/2)i为72.95分钟。在组织摄取实验中，与鳔、脑、性腺、眼睛和肌肉相比，鳃、肾、肝和垂体中通常发现有高水平的累积标记sGnRH-A。共同注射过量的冷sGnRH-A仅导致垂体中标记sGnRH-A的摄取减少，但在其他一些组织中标记sGnRH-A的积累增加。我们的结果表明T(1/2)i与肽对金鱼体内血清GnRH结合蛋白的亲和力之间存在相关性，这表明激素-结合蛋白复合物的形成可能会降低金鱼循环中GnRH的MCR。我们的数据还表明125I-sGnRH-A在雄性和雌性金鱼的垂体中均有特异性摄取，证实垂体是金鱼体内GnRH的主要靶器官。
