Relation between the Brainstem and Hypothalamus in Neural Mechanism of Sleep and Wakefulness

我们主要通过记录脑干中的神经元活动来研究睡眠和觉醒的神经机制，脑干中的神经元活动可能与另一个睡眠控制中心下丘脑有某种关系。本研究观察了电刺激视前区、下丘脑后区、丘脑或额叶皮质对脑干胆碱能神经元活动的影响，同时记录了被盖背外侧核胆碱能神经元的单神经元活动，以探讨脑干胆碱能神经元与下丘脑之间是否存在直接的功能联系，以及在这种联系中可能利用了哪些递质。逆向和顺向反应诱发最频繁时，视前区被刺激。结果表明，视前区是胆碱能投射的最重要的接受器，也是影响胆碱能神经元活动的服务器，催乳素是下丘脑神经元作用于脑干胆碱能神经元的一种可能的递质，因此，我们研究了催乳素对胆碱能神经元活动的影响。少量催乳素在空气压力下从记录电极尖端附近的药物电极局部喷出。只有少数胆碱能神经元被催乳素兴奋。这一结果并不是因为实验技术不好，因为食欲素的喷射同样能剂量依赖性地兴奋胆碱能神经元1至数分钟。（食欲素位于外侧下丘脑的摄食中心神经元中。）实验结果表明，催乳素对脑干胆碱能神经元的作用并不像我们在项目开始时所预期的那样强，但它们受到下丘脑的强烈影响;食欲素确实是下丘脑神经元作用于脑干神经元的递质之一。

We have investigated neural mechanisms of sleep and wakefulness mainly by means of recording neuronal activity in the brainstem, which may have some relation with another center for sleep control, the hypothalamus. The aim of this project is to see whether there are direct functional connections between brainstem cholinergic neurons and the hypothalamus, and which transmitter may be utilized in the connection.Effects of electrical stimulation of the preoptic area, posterior hypothalamus, thalamus or frontal cortex was observed while single neuronal activity of cholinergic neurons was recorded in the laterodorsal tegmental nucleus. Both antidromic and orthodromic responses were evoked most frequently when the preoptic area was stimulated. The result suggests that the preoptic area is the most important structure both as a receiver of the cholinergic projection and as a server to influence cholinergic neuronal activity.As a candidate of transmitter of hypothalamic neurons acting on the brainstem cholinergic neurons, effects of prolactin, which had been shown to increase paradoxical sleep when infused intraventricularly, was examined on neuronal activity of the cholinergic neurons. A small amount of prolactin was ejected locally with air pressure from drug electrode attached in close vicinity of tip of the recording electrode. Only small number of the cholinergic neurons were excited by the prolactin. The result was not due to bad skill of the experiment, since orexin ejected similarly excited the cholinergic neurons dose-dependently for 1 to several minutes.(Orexin is in feeding center neurons of the lateral hypothalamus.) The experiments thus show that action of prolactin on the brainstem cholinergic neurons is not so strong as we expected at the beginning of this project, but they receive some strong influence from the hypothalamus ; orexin is surely one of transmitters of the hypothalamic neurons acting on the brainstem neurons.