Jiménez-Severiano H, D'Occhio M J, Lunstra D D, Mussard M L, Davis T L, Enright W J, Kinder J E
Department of Animal Science, University of Nebraska, Lincoln, NE 68583-0908, USA.
Anim Reprod Sci. 2007 Apr;98(3-4):204-24. doi: 10.1016/j.anireprosci.2006.02.014. Epub 2006 Apr 17.
The objective was to compare the relative response between rams and bulls in characteristics of LH, FSH and testosterone (T) secretion, during and after long-term treatment with GnRH analogs. Animals were treated with GnRH agonist, GnRH antagonist, or vehicle (Control) for 28 days. Serial blood samples were collected on day 21 of treatment, and at several intervals after treatment. Injections of natural sequence GnRH were used to evaluate the capacity of the pituitary to release gonadotropins during and after treatment. Treatment with GnRH agonist increased basal LH and T concentrations in both rams and bulls, with a greater relative increase in bulls. Endogenous LH pulses and LH release after administration of GnRH were suppressed during treatment with GnRH agonist. Treatment with GnRH antagonist decreased mean hormone concentrations, LH and T pulse frequency, and the release of LH and T after exogenous GnRH, with greater relative effects in bulls. Rams previously treated with antagonist had a greater release of LH after administration of GnRH compared with control rams, while rams previously treated with agonist showed a reduced LH response. Bulls previously treated with agonist had reduced FSH concentrations and LH pulse amplitudes compared with control bulls while bulls previously treated with antagonist had greater T concentrations and pulse frequency. The present study was the first direct comparison between domestic species of the response in males to treatment with GnRH analogs. The findings demonstrated that differences do occur between rams and bulls in LH, FSH and testosterone secretion during and after treatment. Also, the consequences of treatment with either GnRH analog can persist for a considerable time after discontinuation of treatment.
目的是比较公羊和公牛在长期使用GnRH类似物治疗期间及之后，促黄体生成素（LH）、促卵泡生成素（FSH）和睾酮（T）分泌特征的相对反应。动物用GnRH激动剂、GnRH拮抗剂或赋形剂（对照）治疗28天。在治疗第21天以及治疗后的几个时间点采集系列血样。注射天然序列GnRH以评估治疗期间及之后垂体释放促性腺激素的能力。GnRH激动剂治疗使公羊和公牛的基础LH和T浓度均升高，公牛的相对升高幅度更大。在GnRH激动剂治疗期间，内源性LH脉冲以及注射GnRH后的LH释放受到抑制。GnRH拮抗剂治疗降低了平均激素浓度、LH和T脉冲频率，以及外源性GnRH后LH和T的释放，对公牛的相对影响更大。与对照公羊相比，先前用拮抗剂治疗的公羊在注射GnRH后LH释放量更大，而先前用激动剂治疗的公羊LH反应降低。与对照公牛相比，先前用激动剂治疗的公牛FSH浓度降低，LH脉冲幅度减小，而先前用拮抗剂治疗的公牛T浓度和脉冲频率更高。本研究是首次对公畜中GnRH类似物治疗反应进行的直接种间比较。研究结果表明，公羊和公牛在治疗期间及之后LH、FSH和睾酮分泌方面确实存在差异。此外，使用任何一种GnRH类似物治疗的后果在停药后都可能持续相当长的时间。
