Schillo K K, Kuehl D, Jackson G L
Biol Reprod. 1985 May;32(4):779-87. doi: 10.1095/biolreprod32.4.779.
Three experiments were done to determine if endogenous opioid peptides (EOPs) mediate the effects of photoperiod on release of luteinizing hormone (LH) and prolactin (Prl) in ovariectomized (OVX) ewes. Intravenous infusions of 0.5 naloxone X h-1 X kg body weight-1 for 3.5 h increased (P less than 0.01) mean plasma concentrations of LH and decreased (P less than 0.025) mean interpulse interval (period) of LH pulses in OVX ewes exposed to long day lengths (16L:8D). Infusions of either 1.0 or 2.5 mg morphine-SO4 X h-1 X kg-1 for 3 h increased (P less than 0.005) the period of LH pulses and increased (P less than 0.005) concentrations of Prl in OVX ewes during the breeding season. In OVX ewes exposed to long (16L:8D) or short (8L:16D) day lengths infusions of naloxone increased (P less than 0.05) mean concentrations of LH, whereas morphine decreased (P less than 0.01) mean concentrations of LH. These effects were attributed to changes in period of LH pulses (P less than 0.001). The drug X photoperiod interactions were not significant for LH parameters. Naloxone did not affect Prl release in either long- or short-day groups, but morphine increased (P less than 0.001) Prl release during long and short day lengths. The effect of morphine on Prl release was more pronounced in ewes exposed to long day lengths than in those exposed to short day lengths. In conclusion, EOPs inhibit the LH pulse generator in OVX ewes. However, it is doubtful that the EOPs mediate the steroid-independent effects of photoperiod on LH release. The results also suggest that photoperiod may influence Prl release via opiate neurons.
进行了三项实验，以确定内源性阿片肽（EOPs）是否介导光周期对去卵巢（OVX）母羊促黄体生成素（LH）和催乳素（Prl）释放的影响。以0.5纳洛酮X h-1 X kg体重-1的剂量静脉输注3.5小时，可使处于长日照（16L:8D）的去卵巢母羊的LH平均血浆浓度升高（P<0.01），并使LH脉冲的平均脉冲间期（周期）缩短（P<0.025）。在繁殖季节，以1.0或2.5毫克硫酸吗啡X h-1 X kg-1的剂量输注3小时，可使去卵巢母羊的LH脉冲周期延长（P<0.005），并使Prl浓度升高（P<0.005）。在处于长日照（16L:8D）或短日照（8L:16D）的去卵巢母羊中，输注纳洛酮可使LH平均浓度升高（P<0.05），而吗啡则使其降低（P<0.01）。这些影响归因于LH脉冲周期的变化（P<0.001）。药物X光周期相互作用对LH参数无显著影响。纳洛酮对长日照或短日照组的Prl释放均无影响，但吗啡可使长日照和短日照条件下的Prl释放增加（P<0.001）。吗啡对Prl释放的影响在长日照母羊中比在短日照母羊中更明显。总之，EOPs抑制去卵巢母羊的LH脉冲发生器。然而，EOPs是否介导光周期对LH释放的非类固醇依赖性影响尚不确定。结果还表明，光周期可能通过阿片神经元影响Prl释放。
