McNeilly J R, Evans N P, Bramley T A, Brown P, Clark A J, Webb R
AFRC Institute of Animal Physiology and Genetics Research, Edinburgh Research Station, Roslin, Midlothian, UK.
J Reprod Fertil. 1993 Jan;97(1):311-5. doi: 10.1530/jrf.0.0970311.
Selection of the luteinizing hormone (LH) response to exogenous gonadotrophin-releasing hormone (GnRH) in sheep has resulted in the establishment of two lines (High and Low) with a fivefold difference in pituitary sensitivity to GnRH. The effect of selection on gonadotrophin gene expression in the presence or absence of an exogenous gonadotrophin-releasing hormone (GnRH) challenge in twenty-week-old ram lambs from both lines was examined. Before treatment with either GnRH or saline, LH and follicle-stimulating hormone (FSH) concentrations were significantly higher in the High line than in the Low line animals (LH and FSH: P < 0.01). One hour after either GnRH or saline, all animals were slaughtered. In the absence of a GnRH challenge, there were significantly higher concentrations of all three gonadotrophin subunit mRNAs in the High line compared with the Low line, corresponding to the higher basal concentrations of LH and FSH. When comparing treatments between the lines, following a GnRH challenge, LH beta subunit mRNA was significantly (P < 0.001) higher in both lines than before the GnRH, whereas there was no significant change in either alpha or FSH beta subunit mRNA. These results indicate that the differences in basal gonadotrophin secretion are related to differences in gonadotrophin subunit mRNAs with the High line animals having an inherently greater amount of all three gonadotrophin subunit mRNAs. Selection has not altered the differential amounts of gonadotrophin subunit mRNAs, since there is an overall increase in all three gonadotrophin subunits. GnRH appears to preferentially control LH beta mRNA in both High and Low line animals.
对绵羊进行选择，使其对外源性促性腺激素释放激素（GnRH）产生黄体生成素（LH）反应，从而建立了两个品系（高反应品系和低反应品系），其垂体对GnRH的敏感性相差五倍。研究了选择对来自两个品系的20周龄公羊羔在有或无外源性促性腺激素释放激素（GnRH）刺激情况下促性腺激素基因表达的影响。在用GnRH或生理盐水处理之前，高反应品系动物的LH和促卵泡激素（FSH）浓度显著高于低反应品系动物（LH和FSH：P < 0.01）。在给予GnRH或生理盐水1小时后，所有动物均被屠宰。在没有GnRH刺激的情况下，高反应品系中所有三种促性腺激素亚基mRNA的浓度均显著高于低反应品系，这与LH和FSH的较高基础浓度相对应。当比较两个品系之间的处理情况时，在GnRH刺激后，两个品系中的LHβ亚基mRNA均显著高于GnRH刺激前（P < 0.001），而α亚基或FSHβ亚基mRNA均无显著变化。这些结果表明，基础促性腺激素分泌的差异与促性腺激素亚基mRNA的差异有关，高反应品系动物固有地具有更多的所有三种促性腺激素亚基mRNA。由于所有三种促性腺激素亚基均有总体增加，选择并未改变促性腺激素亚基mRNA的差异量。GnRH似乎在高反应品系和低反应品系动物中均优先控制LHβ mRNA。
