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去甲肾上腺素通过α2肾上腺素能受体调制小鼠小脑皮层浦肯野细胞自发性放电活动

张旭东^1,2, 王丽菲³, 玄芳玲^1,2, 邱德来^1,2, 张斌斌^1,2,*, 初春平^1,2

¹延边大学脑科学研究中心，延吉 133002；²延边大学医学院生理学与病理生理学教研室，延吉 133002；³长春科技学院医药学院基础医学部，长春 130600

摘要

小脑皮层浦肯野细胞(Purkinje cell, PC)具有简单峰电位(simple spike, SS)和复杂峰电位(complex spike, CS)两种放电形式。我们前期研究发现去甲肾上腺素(noradrenaline, NA)能够抑制PC的CS，双向调节SS，但是NA对SS的增强作用被其兴奋分子层中间神经元产生的强烈抑制所掩盖，目前为止NA对SS放电频率的增强作用机制尚不明确。因此本研究在活体小鼠小脑和急性小脑切片上，应用细胞贴附式及全细胞膜片钳记录与药理学方法，研究了NA增强小脑皮层PC的SS的机制。本研究全程采用100 µmol/L picrotoxin阻断GABAA受体。在体实验结果显示NA明显减少自发性CS的小穗(spikelets)数目，增强SS放电频率，而不影响CS的放电频率；离体实验显示NA减少了电刺激诱发的CS小穗数目和后超极化电位(after hyperpolarization potential, AHP)，增加了SS放电频率，同时NA也减小了平行纤维(parallel fiber, PF)-PC的兴奋性突触后电流(excitatory postsynaptic current, EPSC)的振幅，明显提高了配对脉冲比值(paired-pulse ratio, PPR)。给予α2-肾上腺素能受体(adrenergic receptor, AR)阻断剂育亨宾(yohimbine)能够完全消除NA对SS的增强作用，而α2-AR激动剂UK14304提高了SS放电频率。β-AR阻断剂普萘洛尔(propranolol)不影响NA对PC的作用。上述结果表明阻断GABA能抑制性网络后，NA能够通过活化α2-AR (而不是β-AR)减弱爬行纤维(climbing fiber, CF)-PC突触传递，抑制CS，减小AHP，从而提高了PC的SS放电频率。该研究结果提示蓝斑核的NA能神经元能够通过调节CF-PC突触传递对PC信号输出进行精细微调节。

关键词： 去甲肾上腺素; 简单峰电位; 复杂峰电位; 小脑浦肯野细胞; GABAA受体; 肾上腺素能受体

Noradrenaline modulates the spontaneous firing activities of Purkinje cells via α2-adrenergic receptor in mouse cerebellar cortex

ZHANG Xu-Dong^1,2, WANG Li-Fei³, XUAN Fang-Ling^1,2, QIU De-Lai^1,2, ZHANG Bin-Bin^1,2,*, CHU Chun-Ping^1,2

¹Brain Science Research Center of Yanbian University, Yanji 133002, China；²Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji 133002, China ；³Department of Basic Medicine, College of Medicine, Changchun Sci-Tech University, Changchun 130600, China

Abstract

Cerebellar Purkinje cells (PCs) exhibit two types of discharge activities: simple spike (SS) and complex spike (CS). Previous studies found that noradrenaline (NA) can inhibit CS and bidirectionally regulate SS, but the enhancement of NA on SS is overwhelmed by the strong inhibition of excitatory molecular layer interneurons. However, the mechanism underlying the effect of NA on SS discharge frequency is not clear. Therefore, in the present study, we examined the mechanism underlying the increasing effect of NA on SS firing of PC in mouse cerebellar cortex in vivo and in cerebellar slice by cell-attached and whole-cell recording technique and pharmacological methods. GABAA receptor was blocked by 100 µmol/L picrotoxin in the whole process. In vivo results showed that NA significantly reduced the number of spikelets of spontaneous CS and enhanced the discharge frequency of SS, but did not affect the discharge frequency of CS. In vitro experiments showed that NA reduced the number of CS spikelets and after hyperpolarization potential (AHP) induced by electrical stimulation, and increased the discharge frequency of SS. NA also reduced the amplitude of excitatory postsynaptic current (EPSC) of parallel fiber (PF)-PC and significantly increased the paired-pulse ratio (PPR). Application of yohimbine, an antagonist of α2-adrenergic receptor (AR), completely eliminated the enhancing effect of NA on SS. The α2-AR agonist, UK14304, also increased the frequency of SS. The β-AR blocker, propranolol, did not affect the effects of NA on PC. These results suggest that in the absence of GABAA receptors, NA could attenuate the synaptic transmission of climbing fiber (CF)-PC via activating α2-AR, inhibit CS activity and reduce AHP, thus enhancing the SS discharge frequency of PC. This result suggests that NA neurons of locus coeruleus can finely regulate PC signal output by regulating CF-PC synaptic transmission.

Key words: Noradrenaline; simple spike; complex spike; cerebellar Purkinje cell; GABAA receptor; adrenergic receptor

收稿日期：　　录用日期：

通讯作者：张斌斌　　E-mail: bbZhang@ybu.edu.cn

DOI: 10.13294/j.aps.2022.0034

引用本文：

张旭东, 王丽菲, 玄芳玲, 邱德来, 张斌斌, 初春平. 去甲肾上腺素通过α2肾上腺素能受体调制小鼠小脑皮层浦肯野细胞自发性放电活动[J]. 生理学报 2022; 74 (3): 359-369.

ZHANG Xu-Dong, WANG Li-Fei, XUAN Fang-Ling, QIU De-Lai, ZHANG Bin-Bin, CHU Chun-Ping. Noradrenaline modulates the spontaneous firing activities of Purkinje cells via α2-adrenergic receptor in mouse cerebellar cortex. Acta Physiol Sin 2022; 74 (3): 359-369 (in Chinese with English abstract).