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

据报道，哺乳刺激是哺乳期间抑制 LH 分泌的主要因素。哺乳刺激可能会随着哺乳期的进展或母亲的生理状况而改变，例如哺乳期。幼崽的数量 幼崽的发育程度。我们首先研究了乳神经电刺激是否可以替代哺乳刺激，其次研究了哺乳刺激对去势哺乳大鼠整个泌乳过程中lh分泌模式的影响。 1．电刺激不仅增加了乳腺神经，还增加了隐神经和正中神经的血浆催产素浓度。尽管给予氯丙嗪能够抑制响应固定应激的血浆催产素水平的升高，但给予氯丙嗪未能阻止电刺激乳腺、隐神经和正中神经后发生的升高。当母亲与被封住嘴不吮吸乳头的幼崽放在一起时，血浆催产素水平没有增加。需要进一步的研究来区分催产素对乳神经电刺激的反应与对正中神经和隐神经刺激的反应。2．在完整大鼠的哺乳期第 10 天或第 20 天，脉动 LH 分泌受到强烈抑制，血浆 LH 基线保持在非常低的水平。在卵巢切除大鼠中，基线保持与在完整大鼠中观察到的一样低，在第10天。第20天，基线升高并且在6只卵巢切除哺乳大鼠中的5只中出现脉动分泌。在第 6 天或第 15 天植入雌二醇的两只哺乳大鼠中，每日 LH 激增发生在下午晚些时候。在哺乳第 8 天取出幼仔后，平均 LH 水平以及 LH 脉冲的频率和幅度逐渐增加。在骑自行车的大鼠中，卵巢切除后 LH 脉冲的频率没有变化，尽管平均 LH 水平和 LH 脉冲幅度有所增加。这些结果清楚地表明： 1. 下丘脑-垂体水平的哺乳刺激对脉动 LH 分泌的抑制在哺乳后期被消除。 2.负责雌二醇诱导LH激增的机制不受吸克刺激的影响。 3. 哺乳刺激以与卵巢类固醇不同的方式抑制脉动分泌。较少的

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