Neural mechanism for initiation of labor and maternal behavior

根据我们先前的结果，我们知道，一氧化氮(NO)进入脑室可以抑制妊娠晚期大鼠的分娩和母体行为。这个项目从重新检测先前实验中脑片中NADPH黄递酶组织化学估计的NO活性开始。我们发现，与垂体后叶相反，在分娩期间，垂体前叶不被激活(NeuroReport 8：817-821,1997)。然后用免疫组织化学和NADPH黄递酶组织化学方法检测同一组织标本中的一氧化氮合酶。我们发现一些不表达合酶的垂体前叶细胞与毛细血管接触。这一结果表明，脑垂体腺前叶中的NO可能参与了对流入该腺的血液的控制(Brain Research 784：337-340,1997)。为了了解NO在中枢神经系统控制母体行为中的作用，将NO供体注入哺乳期大鼠的侧脑室。正如我们以前报道的那样，这些大鼠的排乳反射受到抑制，Fos在室旁核、视上核和弓状正中隆起的表达也受到抑制。这些结果表明，NO调节这些核团中神经元的活动，以影响参与控制这些激素分泌和分娩开始的垂体前叶激素(NeuroReport和Brain Research，出版中)。我们想继续这个项目，开发一种新的方法来评估下丘脑每个核团中的NO表达。

From our previous results it is known that nitric oxide (NO) given into the cerebroventricle inhibits delivery and maternal behavior in late pregnant rats. This project has started with reexamining NO activity estimated by NADPH diaphorase histochemistry in the brain slices of the previous experiment. We found that contrary to the posterior pituitary gland , NO activity in the anterior pituitary gland is activated during the time of parturition (NeuroReport 8 : 817-821, 1997). Then we examined NO synthase by immunohistochemistiy and NADPH diaphorase histochemistry in the same tissue preparation. We found that some anterior pituitary cells which express NO synthase locate in contact with capillaries. This result indicates that NO in the anterior pituitary gland may be involved in the control of blood flow into the gland (Brain Research 784 : 337-340, 1997). In order to know the role of NO in the central nervous system to control maternal behavior, NO donor was injected into the lateral ventricle of lactating rats. As we had previously reported, milk-ejection reflex was inhibited in these rats and Fos expression in the paraventricular nucleus, supraoptic nucleus and arcuate-median eminence was suppressed. These results suggest that NO regulates activity of neurons in these nuclei to influence anterior pituitary hormones that are involved in controlling these hormonal secretion and initiation of parturition (NeuroReport and Brain Research, in press). We want to pursue the project to develop a new method to evaluate NO expression in each nucleus of the hypothalamus.