Studies on burst activity of oxytocin neuron similar to that observed at the milk-ejection reflex in the brain slice

对催产素神经元爆发活动的研究类似于在脑切片中观察到的喷乳反射

基本信息

批准号：
09670068
负责人：
NEGORO Hideo
金额：
$ 1.86万
依托单位：
Fukui Medical School
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

At the milk-ejection reflex in rats oxytocin neurons show burst firing for 2-3 seconds in response to sucking stimuli by pups. Consequently oxytocin is secreted from the posterior pituitary gland to eject milk from mammary gland. We aimed to know whether this burst activity originates from endogenous property of the oxytocin neurons. In addition, the involvement of nitric oxide (NO) in the burst fring was examined.From 32 male rats hypothalamic slice preparations were made. We recorded from 65 neurons in the supraoptic nucleus using glass microelectrodes. We identified these neurons as oxytocinergic from their firing pattern. We observed burst activity in 4.6% of these neurons. The mean amplitude of the burst activity was 32.3 spikes, duration was 2.7 sec and after inhibition lasted for 2.7 sec. Additional forty one oxytocin neurons were recorded from other 26 rats after application of phenylephrine at the dose of 10^<-8> - 10^<-5> M.We observed burst activity in 39% of the neurons. The burst firing was irregular. We succeeded in recording from four paired oxytocin neurons, burst activity did not occur synchronously. NO donor, sodium nitroprusside, injected in the lateral ventricle of lactating rats inhibited milk ejection and Fos expression in the paraventricular and supraoptic nuclei.From the these results, we conclude that the mechanism for the burst activity at the milk- ejection reflex at least in part originates from endogenous property of oxytocin neurons and that this mechanism is facilitated by adrenergic input. The synchronizing mechanism is located outside of the paraventricular or supraoptic nuclei and influenced by NO activity .We will continue this project by introducing an equipment that can record from 64 neurons simultaneously.

在大鼠的喷乳反射中，催产素神经元会响应幼崽的吸吮刺激而爆发 2-3 秒。因此，垂体后叶分泌催产素，从乳腺中排出乳汁。我们的目的是了解这种爆发活动是否源于催产素神经元的内源性。此外，还检查了爆裂条纹中一氧化氮（NO）的参与情况。制备了32只雄性大鼠的下丘脑切片制剂。我们使用玻璃微电极记录了视上核中的 65 个神经元。我们从这些神经元的放电模式中鉴定出它们具有催产素能。我们观察到 4.6% 的神经元爆发活动。爆发活动的平均振幅为32.3个尖峰，持续时间为2.7秒，抑制后持续2.7秒。在以10^-8 - 10^-5M的剂量施用去氧肾上腺素后，从另外26只大鼠记录了另外41个催产素神经元。我们观察到39％的神经元中的爆发活动。连发射击是不规则的。我们成功地记录了四对催产素神经元，爆发活动并未同步发生。将 NO 供体硝普钠注射到哺乳期大鼠的侧脑室，可抑制室旁核和视上核的乳汁排出和 Fos 表达。从这些结果中，我们得出结论，乳汁排出反射爆发活动的机制至少在以下方面：部分源于催产素神经元的内源性，并且这种机制是由肾上腺素输入促进的。同步机制位于室旁核或视上核之外，并受 NO 活动的影响。我们将通过引入可以同时记录 64 个神经元的设备来继续这个项目。