NEURAL AND ENDOCRINE SENSITIVITIES TO OPIOIDS DECLINE AS A FUNCTION OF MULTIPARITY IN THE RAT
NEURAL AND ENDOCRINE SENSITIVITIES TO OPIOIDS DECLINE AS A FUNCTION OF MULTIPARITY IN THE RAT
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DOI：
10.1016/0006-8993(92)90950-e
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发表时间：
1992-05-15
期刊：
影响因子：
2.9
通讯作者：
BRIDGES, RS
中科院分区：
文献类型：
--
作者：
MANN, PE;BRIDGES, RS
怀孕期间的激素变化调节分娩时母体行为的发生。此外，-内啡肽和mu-阿片受体的浓度在怀孕期间较高，在哺乳期较低。先前的研究表明，雌性大鼠对吗啡的破坏性行为影响的敏感性随着雌性怀孕和/或哺乳次数的变化而变化。本研究的目的是确定中枢输注内源性阿片样物质-内啡肽是否会破坏母性行为。接下来，我们研究了神经对-内啡肽的敏感性随着反复怀孕而改变的可能性。最后，我们研究了阿片介导的内分泌反应是否也会随着多胎儿而改变。在第一项研究中，将低剂量（0.06-0.72 nmol）的-内啡肽双侧注入哺乳期初产大鼠的内侧视前区（MPOA），破坏了母性行为。当将相当剂量的内啡肽注入年龄匹配的多胎大鼠的MPOA时，内啡肽的行为影响显着减弱。哺乳刺激是一种阿片介导的内分泌反应，初产母鼠分泌的催乳素比多产大鼠多。此外，多胎而非初产的母亲对纳洛酮（一种阿片类拮抗剂）阻断哺乳诱导的催乳素增加的能力不敏感。这些发现表明，当女性经历反复怀孕和哺乳时，对阿片类药物的神经敏感性会降低，这种变化会影响行为和内分泌功能。
Hormonal changes during pregnancy regulate the onset of maternal behavior at parturition. In addition, the concentrations of beta-endorphin and mu-opioid receptors are higher during pregnancy and lower during lactation. Previous studies have shown that sensitivity of female rats to the disruptive behavioral effects of morphine changes as a function of the number of pregnancies and/or lactations the females undergo. The objectives of the present study were to determine whether central infusions of the endogenous opioid, beta-endorphin, would disrupt maternal behavior. Next, we investigated the possibility that the neural sensitivity to beta-endorphin changes with repeated pregnancies. And finally, we examined whether opioid-mediated endocrine responses also change as a function of multiparity. In the first study, bilateral infusions of low doses (0.06-0.72 nmol) of beta-endorphin into the medial preoptic area (MPOA) of lactating, primiparous rats disrupted maternal behavior. When comparable doses of beta-endorphin were infused into the MPOA of age-matched, multiparous rats, the behavioral effects of beta-endorphin were significantly attenuated. In response to suckling stimulation, an opioid-mediated endocrine response, primiparous mothers secreted more prolactin than did multiparous rats. Moreover, multiparous, but not primiparous, mothers were insensitive to the ability of naloxone, an opiate antagonist, to block suckling-induced increases in prolactin. These findings indicate that reductions in neural sensitivity to opioids develop as females undergo repeated pregnancies and lactations, changes which affect both behavioral and endocrine functions.