Lin W W, Ramirez V D
Department of Physiology and Biophysics, University of Illinois, Urbana 61801.
J Reprod Fertil. 1992 Sep;96(1):1-11. doi: 10.1530/jrf.0.0960001.
Push-pull cannulae were implanted toward the tuberal region of the hypothalamus in ten intact New Zealand male rabbits. In the first experiment, rabbits were perfused at different times after castration: 5-10 days (n = 10), 22-31 days (n = 9) and 50-64 days (n = 8). The release, mean amplitude and mean frequency of luteinizing-hormone-releasing hormone (LHRH) signals from 37 perfusions in ten animals were analysed in intact rabbits and at different times after castration. No significant changes in release of LHRH and in amplitude were observed, but the frequency was significantly higher 22-31 days after castration than in intact rabbits (intact: 0.86 +/- 0.12; castrated: 1.20 +/- 0.13 pulses h-1, P < 0.035; n = 9). In Expt 2, testosterone and placebo Silastic capsules were implanted in the castrated rabbits. Perfusions were performed in the following four periods, defined by season and time after testosterone and placebo implants: (i) spring; before implants, (ii) late spring; 0-2 weeks after implants, (iii) summer solstice; 2-4 weeks after implants and (iv) summer; 4-6 weeks after implants. Castrated rabbits were perfused during spring; castrated rabbits with testosterone capsule implants were perfused during late spring, around summer solstice and in summer and castrated rabbits with placebo implants were perfused during periods (iii) and (iv). Castrated animals with placebo implants showed no significant changes in mean LHRH release and amplitude, although the frequency was significantly higher around the summer solstice period than in castrated rabbits perfused in the spring. In castrated rabbits with testosterone implants LHRH release was significantly higher in late spring than around the summer solstice and in the summer. In addition, the concentrations of LHRH in late spring were significantly higher than those of intact and castrated animals. In contrast, mean LHRH amplitude and frequency did not change. Mean amount of LHRH released and amplitude in castrated rabbits with testosterone implants were significantly lower around the summer solstice than in late spring or summer and compared with intact animals around summer solstice and in castrated rabbits in early spring. These data demonstrate that there were no significant changes in the mean amplitude and release of LHRH after castration from 5 and up to 64 days in rabbits with hypothalamic push-pull cannulae, in contrast to the well established dramatic effect of castration on gonadotrophin concentrations. However, there was a small, but significant, increase in the mean frequency of LHRH pulses 22-31 days after castration compared with values from intact rabbits.(ABSTRACT TRUNCATED AT 400 WORDS)
将推挽式套管植入十只完整的新西兰雄性家兔下丘脑的结节区。在第一个实验中，家兔在去势后的不同时间进行灌注：5 - 10天（n = 10）、22 - 31天（n = 9）和50 - 64天（n = 8）。分析了十只动物37次灌注中促黄体生成激素释放激素（LHRH）信号的释放、平均幅度和平均频率，这些信号来自完整家兔以及去势后的不同时间。未观察到LHRH释放和幅度有显著变化，但去势后22 - 31天的频率显著高于完整家兔（完整家兔：0.86 ± 0.12；去势家兔：1.20 ± 0.13次脉冲/小时，P < 0.035；n = 9）。在实验2中，将睾酮和安慰剂硅橡胶胶囊植入去势家兔体内。根据季节以及睾酮和安慰剂植入后的时间，在以下四个时期进行灌注：（i）春季；植入前，（ii）晚春；植入后0 - 2周，（iii）夏至；植入后2 - 4周，（iv）夏季；植入后4 - 6周。春季对去势家兔进行灌注；晚春、夏至前后和夏季对植入睾酮胶囊的去势家兔进行灌注，在（iii）和（iv）时期对植入安慰剂的去势家兔进行灌注。植入安慰剂的去势动物的LHRH平均释放量和幅度没有显著变化，尽管夏至前后的频率显著高于春季灌注的去势家兔。在植入睾酮的去势家兔中，晚春时LHRH释放量显著高于夏至前后和夏季。此外，晚春时LHRH的浓度显著高于完整和去势动物。相比之下，LHRH的平均幅度和频率没有变化。植入睾酮的去势家兔在夏至前后的LHRH释放平均量和幅度显著低于晚春或夏季，与夏至前后的完整动物以及早春的去势家兔相比也是如此。这些数据表明，对于植入下丘脑推挽式套管的家兔，去势后5天至64天LHRH的平均幅度和释放量没有显著变化，这与去势对促性腺激素浓度的显著影响形成对比。然而，与完整家兔的值相比，去势后22 - 31天LHRH脉冲平均频率有小幅但显著的增加。（摘要截短至400字）
