The endocrin control of seasonal reproductive function in the ewe: a marked change in response to the negative feedback action of estradiol on luteinizing hormone secretion.
The endocrin control of seasonal reproductive function in the ewe: a marked change in response to the negative feedback action of estradiol on luteinizing hormone secretion.
复制标题
母羊季节性生殖功能的内分泌控制：雌二醇对黄体生成素分泌负反馈作用的显着变化。
作者：
S. Legan;F. Karsch;D. Foster
一组6只母羊切除卵巢，用含雌二醇-17 β的硅橡胶胶囊皮下给药20个月。虽然这种治疗使血清雌二醇浓度相对稳定地保持在黄体中期水平（3-5 pg/ml），但血清LH浓度存在显著的季节性变化。在整个乏情期，LH水平仍然检测不到。在开始的繁殖季节，有一个显着增加LH浓度的水平接近那些未经处理的卵巢切除母羊。平均LH浓度保持高，直到下一个发情季节开始时，他们急剧下降到无法检测到的水平，他们一直保持到随后的繁殖季节。雌二醇负反馈作用的这些两年一次的变化发生在每只母羊的2-3周内，并且与繁殖季节和完整母羊的乏情期之间的过渡相吻合。与雌二醇处理的卵巢切除母羊LH分泌的双相年度模式相反，...
A group of 6 ewes was ovariectomized and treated sc for 20 months with Silastic capsules containing estradiol-17β. Although this treatment maintained serum estradiol concentrations relatively constant at mid-luteal levels (3–5 pg/ml), there was a dramatic seasonal variation in serum LH concentrations. Throughout anestrus, LH levels remained undetectable. At the onset of the breeding season, there was a striking increase in LH concentrations to levels which approached those in untreated ovariectomized ewes. Mean LH concentrations remained high until the beginning of the next anestrous season, when they decreased precipitously to undetectable levels where they remained until the subsequent breeding season. These biannual changes in the negative feedback action of estradiol occurred within 2–3 weeks in each ewe and coincided with the transitions between the breeding season and anestrus in intact ewes. In contrast to the biphasic annual pattern in LH secretion observed in estradiol-treated ovariectomized ewes...