Clarke I J, Wright P J, Chamley W A, Burman K
J Reprod Fertil. 1984 Mar;70(2):591-7. doi: 10.1530/jrf.0.0700591.
More (P less than 0.05) post-partum acyclic ewes (8/9) showed evidence of pulsatile LH release than did seasonally anoestrous ewes (2/8). Mean plasma prolactin concentrations were higher (P less than 0.05) in the post-partum ewes than in the seasonally anoestrous ewes. Hypothalamic and pituitary cytosol oestrogen receptor number, median eminence GnRH content and pituitary LH, FSH and prolactin contents were similar in the two groups of ewes. The number of nuclear-bound oestrogen receptors was greater (P less than 0.01) in pituitaries from seasonally anoestrous ewes than in pituitaries from post-partum ewes. These data suggest that the basis of acyclicity in seasonally anoestrous ewes and in post-partum ewes is probably due to their inability to generate LH pulse frequencies similar to that in the follicular phase of the oestrous cycle. The higher LH pulse frequency in post-partum ewes, compared to that in seasonally anoestrous ewes, suggests that pregnancy may partly negate the reduction in LH secretion that is associated with photoperiod-induced acyclicity. The lower number of nuclear-bound oestrogen receptors in post-partum ewes suggests that there may be lower plasma oestrogen levels and less ovarian follicular growth than in non-suckling anoestrous ewes.
与季节性乏情母羊（2/8）相比，更多（P<0.05）产后无发情周期的母羊（8/9）表现出促黄体生成素（LH）脉冲式释放的迹象。产后母羊的血浆催乳素平均浓度高于季节性乏情母羊（P<0.05）。两组母羊的下丘脑和垂体胞质雌激素受体数量、正中隆起促性腺激素释放激素（GnRH）含量以及垂体LH、促卵泡生成素（FSH）和催乳素含量相似。季节性乏情母羊垂体中与核结合的雌激素受体数量比产后母羊垂体中的更多（P<0.01）。这些数据表明，季节性乏情母羊和产后母羊无发情周期的基础可能是它们无法产生与发情周期卵泡期相似的LH脉冲频率。与季节性乏情母羊相比，产后母羊的LH脉冲频率更高，这表明怀孕可能部分抵消了与光周期诱导的无发情周期相关的LH分泌减少。产后母羊中与核结合的雌激素受体数量较少，这表明与非哺乳乏情母羊相比，其血浆雌激素水平可能较低，卵巢卵泡生长较少。
