Excitatory effect of norepinephrine on neurons in the inferior vestibular nucleus and the underlying receptor mechanism

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• 作者：Shi-Yu Peng ; Qian-Xing Zhuang ; Yong-Xiao Zhang ; Xiao-Yang Zhang ; Jian-Jun Wang and Jing-Ning Zhu
• 刊名：Journal of Neuroscience Research
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：94
• 期：8
• 页码：736-748
• 全文大小：879K
• ISSN：1097-4547

文摘

The central noradrenergic system, originating mainly from the locus coeruleus in the brainstem, plays an important role in many physiological functions, including arousal and attention, learning and memory, anxiety, and nociception. However, little is known about the roles of norepinephrine (NE) in somatic motor control. Therefore, using extracellular recordings on rat brainstem slices and quantitative real-time RT-PCR, we investigate the effect and mechanisms of NE on neuronal activity in the inferior vestibular nucleus (IVN), the largest nucleus in the vestibular nuclear complex, which holds an important position in integration of information signals controlling body posture. Here, we report that NE elicits an excitatory response on IVN neurons in a concentration-dependent manner. Activation of α₁- and β₂-adrenergic receptors (ARs) induces an increase in firing rate of IVN neurons, whereas activation of α₂-ARs evokes a decrease in firing rate of IVN neurons. Therefore, the excitation induced by NE on IVN neurons is a summation of the excitatory components mediated by coactivation of α₁- and β₂-ARs and the inhibitory component induced by α₂-ARs. Accordingly, α₁-, α₂-, and β₂-AR mRNAs are expressed in the IVN. Although β₁-AR mRNAs are also detected, they are not involved in the direct electrophysiological effect of NE on IVN neurons. All these results demonstrate that NE directly regulates the activity of IVN neurons via α₁-, α₂-, and β₂-ARs and suggest that the central noradrenergic system may actively participate in IVN-mediated vestibular reflexes and postural control.