Aurich C, Schlote S, Hoppen H O, Klug E, Hoppe H, Aurich J E
Institut für Reproduktionsmedizin, Tierärztliche Hochschule Hannover, Germany.
J Endocrinol. 1994 Jul;142(1):139-44. doi: 10.1677/joe.0.1420139.
To investigate an involvement of endogenous opioids in the regulation of circannual changes in reproductive activity, effects of the opioid antagonist naloxone on the concentration of immunoreactive and bioactive luteinizing hormone (LH) in plasma were measured in mares during the anovulatory season. Naloxone (0.5 mg/kg i.v.) caused a significant increase (P < 0.05) in immunoreactive as well as bioactive LH concentration in plasma. The amplitude of the increase in LH concentrations measured with an in vitro bioassay was more pronounced than the amplitude of the increase in LH secretion determined by radioimmunoassay. This indicates that although in seasonal anovulatory mares the bioactivity of LH in plasma is low, highly bioactive LH is present in the anterior pituitary and can be released by naloxone. The LH response to naloxone did not depend on the degree of ovarian follicular activity. It can be concluded that a tonic opioid inhibition of LH release is present in mares during at least part of the anovulatory season and that endogenous opioids seem to be involved in the regulation of seasonal reproductive activity in the horse. In contrast to the situation during the breeding season, the opioid systems regulating LH release are activated independently of luteal progesterone.
为研究内源性阿片类物质在调节生殖活动的年周期变化中的作用，在无排卵季节测定了阿片类拮抗剂纳洛酮对母马血浆中免疫反应性和生物活性促黄体生成素（LH）浓度的影响。静脉注射纳洛酮（0.5mg/kg）导致血浆中免疫反应性LH和生物活性LH浓度显著升高（P<0.05）。用体外生物测定法测得的LH浓度升高幅度比放射免疫测定法测定的LH分泌升高幅度更明显。这表明，尽管在季节性无排卵母马中血浆LH的生物活性较低，但前垂体中存在高生物活性的LH，且可被纳洛酮释放。LH对纳洛酮的反应不依赖于卵巢卵泡活动程度。可以得出结论，在至少部分无排卵季节，母马存在对LH释放的阿片类物质紧张性抑制，且内源性阿片类物质似乎参与了马的季节性生殖活动调节。与繁殖季节的情况相反，调节LH释放的阿片类系统独立于黄体孕酮被激活。
