Berglund L A, Sisk C L
Department of Psychology, Michigan State University, East Lansing 48824-1117.
Biol Reprod. 1990 Aug;43(2):335-9. doi: 10.1095/biolreprod43.2.335.
The pituitary response to three different doses of exogenously administered LHRH was examined in prepubertal (9-wk-old) and postpubertal (32-wk-old) male ferrets. The doses of 5, 10, and 15 ng LHRH/kg body weight tested in this study produced dose-related increases in circulating LH concentrations in both pre- and postpubertal groups. In addition, a significant effect of age on LH response was observed, with the prepubertal animals demonstrating significantly greater serum LH values in response to the two higher doses than the postpubertal males. Prepubertal ferrets also exhibited a significant increase in endogenous LH pulse amplitude in sampling periods following exogenous administration of LHRH compared to baseline pulse amplitudes in periods prior to the LHRH infusions. These results suggest that the low frequency of endogenous LH pulses previously observed in prepubertal ferrets is not due to unresponsiveness of the pituitary gland to LHRH. Thus, suppression of the hypothalamo-hypophyseal axis observed in the prepubertal ferret is probably mediated at the level of the hypothalamus.
在青春期前（9周龄）和青春期后（32周龄）的雄性雪貂中，研究了垂体对外源性给予的三种不同剂量促黄体生成素释放激素（LHRH）的反应。本研究中测试的5、10和15 ng LHRH/千克体重剂量，在青春期前和青春期后组中均使循环中的促黄体生成素（LH）浓度出现与剂量相关的增加。此外，观察到年龄对LH反应有显著影响，青春期前动物对两种较高剂量的反应所产生的血清LH值显著高于青春期后雄性动物。与LHRH输注前各时期的基线脉冲幅度相比，青春期前雪貂在给予外源性LHRH后的采样期内，内源性LH脉冲幅度也显著增加。这些结果表明，之前在青春期前雪貂中观察到的内源性LH脉冲低频现象并非由于垂体对LHRH无反应。因此，青春期前雪貂中观察到的下丘脑 - 垂体轴抑制可能是在下丘脑水平介导的。
