The opiate peptide enkephalin has been immunohistochemically localized within specific populations of climbing fibers and mossy fibers in the opossum's cerebellum. The intention of the present study was to determine the physiological effects of this peptide on Purkinje cell activity as well as to examine interactions between this peptide and the excitatory amino acids glutamate and aspartate. Iontophoretic application of enkephalin onto Purkinje cells in the posterior lobe vermis and adjacent hemisphere suppressed activity in nine of 16 (56%) spontaneously active units. Enkephalin increased the spontaneous activity of one unit and had no effect on six (38%) of the units. In addition, this peptide blocked the excitatory effects elicited by iontophoretic application of glutamate in 34 of 35 (97%) units tested and of aspartate in all cases. Enkephalin had no effect on one cell activated by glutamate. Simultaneous application of naloxone, a nonspecific opiate receptor antagonist, did not block the suppressive effects of enkephalin. Rather, there was a potentiation of suppressive responses as compared to that seen when each is applied alone. The results suggest that classically defined excitatory afferent projections to the cerebellum may be capable of both exciting and suppressing the activity of their target neurons. The excitatory action is likely mediated by an amino acid, whereas the release of the peptide enkephalin results in a decrease in unit activity. Further, it appears that enkephalin mediates its suppressive effect through mechanisms that are not mediated by opioid receptors.

译文

鸦片肽脑啡肽已在免疫组织化学上定位在负鼠小脑的攀援纤维和苔藓纤维的特定人群中。本研究的目的是确定该肽对浦肯野细胞活性的生理作用,并检查该肽与兴奋性氨基酸谷氨酸和天冬氨酸之间的相互作用。脑啡肽在后叶ver和邻近半球的浦肯野细胞上的离子电渗应用抑制了16个 (56% 个) 自发活动单位中的9个的活性。脑啡肽增加了一个单位的自发活动,对六个 (38%) 单位没有影响。此外,在所有情况下,该肽阻断了谷氨酸在测试的35 (97%) 单位中的34个和天冬氨酸的离子电渗应用引起的兴奋作用。脑啡肽对谷氨酸激活的一个细胞没有影响。同时应用非特异性阿片受体拮抗剂纳洛酮不会阻止脑啡肽的抑制作用。相反,与单独应用每种方法相比,抑制反应具有增强作用。结果表明,经典定义的对小脑的兴奋性传入投射可能既能够刺激又能够抑制其目标神经元的活动。兴奋作用可能由氨基酸介导,而肽脑啡肽的释放导致单位活性降低。此外,脑啡肽似乎通过阿片受体不介导的机制介导其抑制作用。

+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