Chou H F, Johnson A L, Williams J B
Life Sci. 1985 Dec 30;37(26):2459-65. doi: 10.1016/0024-3205(85)90602-2.
The luteinizing hormone (LH)-releasing activity of two distinct chicken luteinizing hormone releasing hormones ([Gln8]-LHRH and [His5, Trp7, Tyr8]-LHRH) were evaluated in white Leghorn cockerels. In the first study, thirty birds were randomly allotted to five groups and injected, i.v., with 0.9% saline, [Gln8]-LHRH (cLHRH I, 1 microM or 10 microM) or [His5, Trp7, Tyr8]-LHRH, (cLHRH II; 1 microM or 10 microM). Blood samples were drawn prior to and through 60 min following the injection, and plasma was collected for LH determination. In the second study, anterior pituitary cells from cockerels were dispersed and preincubated for 1 hr. Approximately 1.5 X 10(5) cells per tube were incubated with either Medium 199 buffer (control), 8-bromo-cAMP or various doses of cLHRH I or cLHRH II at final concentrations ranging from 0.02 to 100.0 nM. At the end of a two hour incubation, supernatant was collected and the concentration of LH determined. Injection of cLHRH I or cLHRH II at 1 microM and 10 microM levels caused a significant increase in blood LH concentrations which peaked 5 min following injection. There were, however, no differences between the stimulatory effect of cLHRH I compared to cLHRH II at either dose. On the other hand, cLHRH II was found to be 4.7 times more potent than cLHRH I in stimulating LH release from dispersed pituitary cells. It is suggested that cLHRH II may have greater affinity for the gonadotroph receptor, greater uptake by the cell, and/or that it may be more resistant to in vitro degradation than cLHRH I. On the other hand, an extra pituitary site of degradation may be more effective in metabolizing cLHRH II, resulting in its equipotency with cLHRH I, in vivo.
在白来航公鸡中评估了两种不同的鸡促黄体激素释放激素（[谷氨酰胺8]-促黄体激素释放激素和[组氨酸5、色氨酸7、酪氨酸8]-促黄体激素释放激素）的促黄体激素（LH）释放活性。在第一项研究中，将30只鸡随机分为五组，静脉注射0.9%生理盐水、[谷氨酰胺8]-促黄体激素释放激素（鸡促黄体激素释放激素I，1微摩尔或10微摩尔）或[组氨酸5、色氨酸7、酪氨酸8]-促黄体激素释放激素（鸡促黄体激素释放激素II；1微摩尔或10微摩尔）。在注射前及注射后60分钟内采集血样，收集血浆用于测定LH。在第二项研究中，将公鸡的垂体前叶细胞分散并预孵育1小时。每管约1.5×10⁵个细胞与M199缓冲液（对照）、8-溴环磷腺苷或不同剂量的鸡促黄体激素释放激素I或鸡促黄体激素释放激素II一起孵育，终浓度范围为0.02至100.0纳摩尔。孵育两小时结束时，收集上清液并测定LH浓度。注射1微摩尔和10微摩尔水平的鸡促黄体激素释放激素I或鸡促黄体激素释放激素II导致血液LH浓度显著升高，在注射后5分钟达到峰值。然而，在任一剂量下，鸡促黄体激素释放激素I与鸡促黄体激素释放激素II的刺激作用之间没有差异。另一方面，发现鸡促黄体激素释放激素II在刺激分散的垂体细胞释放LH方面比鸡促黄体激素释放激素I强4.7倍。提示鸡促黄体激素释放激素II可能对促性腺激素细胞受体具有更高的亲和力，被细胞摄取的能力更强，和/或它可能比鸡促黄体激素释放激素I更耐体外降解。另一方面，垂体外的一个降解位点可能在代谢鸡促黄体激素释放激素II方面更有效，导致其在体内与鸡促黄体激素释放激素I等效。
