Wager-Srdar S A, Gannon M, Levine A S
Physiol Behav. 1987;39(5):669-72. doi: 10.1016/0031-9384(87)90172-7.
Previous studies have shown that estradiol and progesterone can alter the response of female rats to naloxone. For example, ovariectomized rats receiving estradiol were found to be less sensitive to the anorexic effect of naloxone than ovariectomized rats receiving oil (vehicle) or progesterone. In the present paper, we evaluated the effect of naloxone on nocturnal food intake in female rats during each stage of the estrous cycle to determine whether changing levels of gonadal hormones in intact female rats would affect their response to naloxone. To evaluate the role testosterone might play in modulating the male rat's feeding response to naloxone we studied the effect of peripherally administered naloxone (0.1, 1.0 and 10 mg/kg) on nocturnal food intake of intact, castrate and castrate + testosterone propionate male rats. During late metestrus, diestrus and proestrus, female rats decreased nocturnal food intake following the administration of naloxone (1.0 and 10 mg/kg) SC (p less than 0.05). During estrus, female rats failed to decrease food intake following any of the doses of naloxone administered. The male rat's response to naloxone does not appear to be altered by the presence or absence of testosterone. Thus, the level of estradiol and progesterone at different stages of the estrous cycle may affect the female rat's response to the satiety effect of naloxone.
以往的研究表明，雌二醇和孕酮可改变雌性大鼠对纳洛酮的反应。例如，发现接受雌二醇的去卵巢大鼠比接受油剂（赋形剂）或孕酮的去卵巢大鼠对纳洛酮的厌食作用敏感性更低。在本文中，我们评估了纳洛酮对处于发情周期各阶段的雌性大鼠夜间食物摄入量的影响，以确定完整雌性大鼠体内性腺激素水平的变化是否会影响它们对纳洛酮的反应。为了评估睾酮在调节雄性大鼠对纳洛酮的进食反应中可能发挥的作用，我们研究了外周注射纳洛酮（0.1、1.0和10mg/kg）对完整、去势及去势+丙酸睾酮雄性大鼠夜间食物摄入量的影响。在动情后期、间情期和动情前期，雌性大鼠皮下注射纳洛酮（1.0和10mg/kg）后夜间食物摄入量减少（p<0.05）。在发情期，雌性大鼠在给予任何剂量的纳洛酮后均未出现食物摄入量减少的情况。雄性大鼠对纳洛酮的反应似乎不受睾酮存在与否的影响。因此，发情周期不同阶段的雌二醇和孕酮水平可能会影响雌性大鼠对纳洛酮饱腹感效应的反应。
