Malven P V, Hudgens R E
J Anim Sci. 1987 Jul;65(1):196-202. doi: 10.2527/jas1987.651196x.
Involvement of endogenous opioids in inhibition of luteinizing hormone (LH) release and stimulation of prolactin (PRL) release was investigated by injecting the opioid antagonist naloxone into 18 ewes on d 7 and 8, d 12 and 13, and d 18 and 19 postpartum. Compared with control injections of saline, iv naloxone (1 mg/kg) increased serum concentrations of LH and decreased serum PRL in samples collected 15, 30 and 45 min after each injection. Ewes lambing in the spring (March) or autumn (September and October) that nursed one or two lambs did not differ in their LH and PRL responses to naloxone. Autumn-lambing ewes from which lambs were weaned within 1 d after parturition did not differ from ewes of the autumn-nursed group in any of the following characteristics: 1) serum LH increases following naloxone, 2) basal secretion of LH, 3) postpartum interval to first increase in serum progesterone and 4) relative decrease in serum PRL after naloxone despite large differences in basal PRL secretion. In summary, postpartum expression of a naloxone-reversible inhibition of LH release and stimulation of PRL secretion did not depend on suckling stimuli or differ between autumn and spring parturitions.
通过在产后第7和8天、第12和13天以及第18和19天给18只母羊注射阿片类拮抗剂纳洛酮，研究内源性阿片类物质对促黄体生成素（LH）释放的抑制作用和对催乳素（PRL）释放的刺激作用。与注射生理盐水的对照相比，静脉注射纳洛酮（1毫克/千克）后，在每次注射后15、30和45分钟采集的样本中，血清LH浓度升高，血清PRL浓度降低。在春季（3月）或秋季（9月和10月）产羔并哺育一两只羔羊的母羊，其对纳洛酮的LH和PRL反应没有差异。产后1天内断奶的秋季产羔母羊，在以下任何特征方面与秋季哺乳组母羊均无差异：1）纳洛酮注射后血清LH升高；2）LH的基础分泌；3）产后至血清孕酮首次升高的间隔时间；4）尽管基础PRL分泌存在很大差异，但纳洛酮注射后血清PRL的相对降低。总之，纳洛酮可逆性抑制LH释放和刺激PRL分泌的产后表现不依赖于哺乳刺激，且在秋季和春季分娩之间没有差异。
