Responses to [D-Ala2, MePhe4, Gly-ol5]enkephalin, a selective agonist for mu-receptors, were recorded intracellularly from 26 neurons in slices of guinea-pig hypothalamus. Of eight cells tested in the supraoptic nucleus, all of which had electrical properties characteristic of magnocellular neuroendocrine cells, four were sensitive to the agonist applied in the perfusion bath or with microdrops. The main effect was a decrease or suppression of spontaneous firing. In the paraventricular nucleus, seven of 18 cells tested also had electrophysiological characteristics similar to magnocellular neurons: two of them were sensitive to the mu-agonist and the effect was similar to that observed in the supraoptic nucleus. The remaining paraventricular neurons displayed low-threshold Ca2+ spikes, and thus had electrophysiological characteristics different from putative magnocellular neurons. Ten of 11 cells with low-threshold Ca2+ spikes were hyperpolarized by more than 10 mV by the mu-agonist, and showed a 33 +/- 1.9% (S.E.M.) decrease in input resistance. In both types of cells, when synaptic transmission was blocked with tetrodotoxin, the mu-agonist could still induce a hyperpolarization, suggesting that the effect was in part direct. Hyperpolarization was also obtained when the Cl- reversal potential was shifted to more positive values by using KCl electrodes, thus excluding a Cl- conductance mechanism. These results provide evidence that opioid peptides can directly inhibit hypothalamic neurons, that the mechanism is an increase in K+ conductance, and that two types of hypothalamic neurons appear to have different sensitivities to a mu-agonist.

译文

从豚鼠下丘脑切片中的26个神经元在细胞内记录了对 [D-Ala2,MePhe4,Gly-ol5] 脑啡肽 (mu受体的选择性激动剂) 的反应。在视上核中测试的八个细胞中,所有这些细胞均具有大细胞神经内分泌细胞的电特性,其中四个对灌注浴或微滴中使用的激动剂敏感。主要效果是减少或抑制自发发射。在室旁核中,测试的18个细胞中有7个具有类似于大细胞神经元的电生理特征: 其中两个对mu激动剂敏感,其作用类似于在视上核中观察到的作用。其余的室旁神经元显示出低阈值的Ca2尖峰,因此具有与假定的大细胞神经元不同的电生理特征。具有低阈值Ca2尖峰的11个细胞中的10个被mu激动剂超极化超过10 mV,并显示输入阻力降低了33/- 1.9% (s.e.M.)。在两种类型的细胞中,当河豚毒素阻断突触传递时,mu激动剂仍可诱导超极化,这表明该作用部分是直接的。当使用KCl电极将Cl反转电位移至更多正值时,也获得了超极化,从而排除了Cl电导机制。这些结果提供了证据,表明阿片肽可以直接抑制下丘脑神经元,其机制是K电导的增加,并且两种类型的下丘脑神经元似乎对mu激动剂具有不同的敏感性。

+1
+2
100研值 100研值 ¥99课程
检索文献一次
下载文献一次

去下载>

成功解锁2个技能,为你点赞

《SCI写作十大必备语法》
解决你的SCI语法难题!

技能熟练度+1

视频课《玩转文献检索》
让你成为检索达人!

恭喜完成新手挑战

手机微信扫一扫,添加好友领取

免费领《Endnote文献管理工具+教程》

微信扫码, 免费领取

手机登录

获取验证码
登录