Neuroendocrine studies on modulation of the function of the hypothalmo-pituitary-gonadal axis with nutrients

据报道，哺乳刺激是哺乳期抑制LH分泌的主要因素。哺乳刺激可随哺乳期的进展或母体的生理状况如幼崽数量、幼崽发育程度而变化。我们首先研究了电刺激乳腺神经是否可以作为哺乳刺激的替代物，其次研究了哺乳刺激对去卵巢泌乳大鼠泌乳期lh分泌模式的影响。电刺激乳神经、隐神经和正中神经均可使血浆催产素浓度升高。虽然氯丙嗪adminidtration能够抑制血浆催产素水平的增加，在响应制动应激，氯丙嗪管理未能阻止后发生的增加，电刺激乳腺，隐神经和正中神经。无增量 关于我们 当母亲与幼鼠放在一起时，幼鼠的嘴被封住，乳头没有被盖住，血浆催产素水平下降。电刺激乳腺神经与刺激正中神经和隐神经对催产素的反应需要进一步的研究.在哺乳期第10天或第20天，在血浆LH基线保持非常低的完整大鼠中，脉冲式LH分泌受到强烈抑制。去卵巢大鼠的基线与正常大鼠一样低，第10天，第20天，6只去卵巢哺乳大鼠中有5只出现基线升高和搏动性分泌。在第6天或第15天植入雌二醇的两种泌乳大鼠中，每日LH峰均发生在下午晚些时候。平均LH水平和LH脉冲的频率和幅度逐渐增加后，删除的幼崽在哺乳期第8天。在骑自行车的大鼠中，卵巢切除后LH脉冲的频率不变，但平均LH水平和LH脉冲的幅度增加。这些结果清楚地表明：1.哺乳刺激对下丘脑-垂体水平LH脉动分泌的抑制在哺乳后期被消除。2.雌二醇诱导LH峰的机制不受哺乳动物的影响。3.哺乳期Sitmulus抑制脉冲分泌的方式与卵巢类固醇不同。少

The suckling stimulus has been reported to be a dominant factor suppressing LH secretion during lactation. The suckling stimulus could change with the advancement of lactation or physiologcal condition of mothers e.g. number of pups the degree of pups development. We, first, studied whether or not the electrical stimulation of the mammary nerve could be used as a substitute for the suckling sitmulus, and secondly, we studied effects of thesuckling sitmulus on the secretory pattern of lh in ovariectomized lactating rats throughout the lactating peruid.1. The electrical sitmulation of not only the mammary nerve but also the saphoenous and median nerves increased the plasme oxytocin concentration. Although chlorpromazine adminidtration was able to inhibit the increase of plasma oxytocin level in response to the immobilization stress, chlorpromazine administration failed to prevent the increase occurring after the electrical stimulation of the mammary, saphenous and median nerves. No incre … More ase in the plasma oxytocin levels when the mother was placed with pups whose mouths were sealed not to suckle the teat. Further studies are required to discriminate the oxytocin response to the electrical stimulation of the mammary nerve from that to the sitmulation of the median and saphenous nerves.2. Pulsatile LH secretion was strongly suppressed on either day 10 or 20 of lactation in intact rats in which the base line of plasma LH was kept very low. In ovariectomized rats the base line was kept as low as that observed in intact rats on day 10 day 20 the base line raised and pulsatile secretion appeared in 5 out of 6 ovraiectomized lactating rats. Daily LH surges occurred in the late afternoon in both lactating rats inplanted with estradiol on day 6 or 15. The mean LH level and the frequency and amplitude of LH pulses gradually increased after removal of pups on day 8 of lactation. In cycling rats the frequency of LH pulses was unchanged after ovariectomy, although the mean LH level and the amplitude of LH pulses increased. These results clearly indicate: 1. Suppression of pulsatile LH secretion by the suckling stimulus at the hypothalamo-pituitary level is removed in late lactation. 2. The mechanisms responsible for the estradiol induced LH surge are not impaired by the sucklig sitmulus. 3. The suckling sitmulus suppresses pulsatile secretion in a different manner from that of ovarian steroids. Less