Muralidhar K, Maneckjee R, Moudgal N R
Endocrinology. 1977 Apr;100(4):1137-42. doi: 10.1210/endo-100-4-1137.
The mechanism whereby the reciprocal relationship between the plasma levels of prolactin and HL is maintained in lactating rats under different degrees of suckling stimulus has been investigated in the present study. Plasma levels of luteinizing hormone (LH) in lactating rats suckling two pups could be reduced significantly by injecting prolactin (PRL). This reduction was also evident in ovariectomized and ovariectomized-adrenalectomized lactating rats, thus excluding mediation of the inhibitory effect by steroids from end-organs. The in vivo response of the pituitary to exogenous LHRH was lower in rats suckling eight pups than those suckling two pups. Prolactin administered prior to LHRH caused an inhibition of the response of the pituitary to exogenous LHRH in rats suckling two pups. These data provide evidence for the hypothesis that in the lactating rat, in the presence of minimal suckling stimulus, the causative factor for reducing serum LH levels is prolactin, which acts by altering the pituitary responsiveness to LHRH.
本研究探讨了在不同程度的哺乳刺激下，泌乳大鼠体内催乳素（PRL）水平与促黄体生成素（HL）之间的相互关系得以维持的机制。给哺乳两只幼崽的泌乳大鼠注射催乳素（PRL）后，其血浆促黄体生成素（LH）水平可显著降低。这种降低在去卵巢和去卵巢-肾上腺切除的泌乳大鼠中也很明显，从而排除了类固醇从终末器官介导抑制作用的可能性。与哺乳两只幼崽的大鼠相比，哺乳八只幼崽的大鼠垂体对外源性促性腺激素释放激素（LHRH）的体内反应较低。在给外源性LHRH之前给予催乳素可抑制哺乳两只幼崽的大鼠垂体对外源性LHRH的反应。这些数据为以下假设提供了证据：在泌乳大鼠中，在最小哺乳刺激的情况下，降低血清LH水平的致病因素是催乳素，其作用方式是改变垂体对LHRH的反应性。
