Ruiz E, Osorio R, Osorio E, Ortega E
Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Granada, Spain.
Biochem Mol Biol Int. 1993 Aug;30(6):1093-100.
To evaluate whether the median eminence (ME) is a site of action of opioids on gonadotropin secretion, and to determinate the role of estradiol (E) and progesterone (P) in modifying these secretion in response to naloxone, we injected naloxone (1, 2.5 and 5 micrograms) into the ME in ovariectomized rats treated with estradiol benzoate (OVX+E) or ovariectomized rats treated with estradiol benzoate plus progesterone (OVX+E+P), and measured LH and FSH serum levels 10 and 30 min postinjection. Naloxone injection at doses of 2.5 and 5 micrograms significantly increased serum LH levels in OVX+E animals 10 and 30 min postinjection, whereas naloxone injection at all doses in OVX+E+P rats did not have any significant effect on LH secretion 10 and 30 min postinjection, when compared with values obtained in controls injected with saline. The injection of naloxone into the ME did not modify FSH secretion. We conclude that naloxone, acting within the ME, can elicit LH release in OVX+E rats, while it abolishes this effect in OVX+E+P rats.
为评估正中隆起（ME）是否为阿片类药物对促性腺激素分泌的作用位点，并确定雌二醇（E）和孕酮（P）在纳洛酮作用下对这些分泌的调节作用，我们将纳洛酮（1、2.5和5微克）注入接受苯甲酸雌二醇治疗的去卵巢大鼠（OVX + E）或接受苯甲酸雌二醇加孕酮治疗的去卵巢大鼠（OVX + E + P）的正中隆起，并在注射后10分钟和30分钟测量血清促黄体生成素（LH）和促卵泡生成素（FSH）水平。注射2.5微克和5微克剂量的纳洛酮可使OVX + E动物在注射后10分钟和30分钟时血清LH水平显著升高，而与注射生理盐水的对照组相比，OVX + E + P大鼠注射所有剂量的纳洛酮在注射后10分钟和30分钟时对LH分泌均无显著影响。向正中隆起注射纳洛酮并未改变FSH分泌。我们得出结论，在正中隆起内起作用的纳洛酮可引起OVX + E大鼠LH释放，而在OVX + E + P大鼠中则消除了这种作用。
