Department of Physiology and Pathophysiology, Yanbian University College of Basic Medicine and Key Laboratory of Natural Resources of Changbai Mountain & Functional Molecules (Yanbian University) Ministry of Education, Yanji 133002, Jilin Province, China.
Brain Res. 2012 Mar 14;1443:27-33. doi: 10.1016/j.brainres.2012.01.020. Epub 2012 Jan 17.
In the vestibular nuclei, acute hypotension induces excitation of electrical activity and expression of c-Fos protein and phosphorylated extracellular signal-regulated kinase (pERK). Expression of c-Fos protein and pERK is mediated by the excitatory neurotransmitter, glutamate. We investigated the signaling pathway of glutamate and its receptors in the vestibular nuclei following acute hypotension in conscious rats. Glutamate release and the expression of c-Fos protein in the medial vestibular nuclei (MVN) were measured by microdialysis and immunohistochemical analysis, respectively. We compared the responses of rats with unilateral labyrinthectomy to unaltered controls. Acute hypotension was induced by infusing sodium nitroprusside (SNP) into the femoral vein. In the control group, glutamate release and the expression of c-Fos protein increased in the bilateral MVN following acute hypotension. In the unilateral labyrinthectomy group, glutamate release and the expression of c-Fos protein increased in the MVN contralateral to the lesion, but did not change in the ipsilateral MVN following acute hypotension. Microinjection of NMDA or AMPA into the lateral ventricle increased the expression of c-Fos protein in the bilateral MVN of conscious intact labyrinthine rats. However, after intracerebroventricular microinjection of MK-801 or CNQX little c-Fos protein was expressed in the bilateral MVN of these rats following acute hypotension. These results suggest that in response to acute hypotension, excitatory afferent signals from the peripheral vestibular receptors release glutamate into postsynaptic neurons in the vestibular nuclei. These excitatory signals are transmitted through the NMDA receptors and AMPA receptors of glutamate in the vestibular system.
在前庭神经核中，急性低血压会引起电活动的兴奋和 c-Fos 蛋白及磷酸化细胞外信号调节激酶 (pERK) 的表达。c-Fos 蛋白和 pERK 的表达是由兴奋性神经递质谷氨酸介导的。我们研究了在清醒大鼠急性低血压后，前庭神经核中谷氨酸及其受体的信号通路。通过微透析测量谷氨酸释放，通过免疫组织化学分析测量 c-Fos 蛋白的表达。我们比较了单侧迷路切除大鼠与未改变对照的反应。通过向股静脉输注硝普钠 (SNP) 来诱导急性低血压。在对照组中，急性低血压后双侧前庭神经核 (MVN) 中的谷氨酸释放和 c-Fos 蛋白的表达增加。在单侧迷路切除组中，损伤对侧 MVN 中的谷氨酸释放和 c-Fos 蛋白的表达增加，但急性低血压后同侧 MVN 中的谷氨酸释放和 c-Fos 蛋白的表达没有变化。将 NMDA 或 AMPA 微注射到侧脑室会增加清醒完整迷路大鼠双侧 MVN 中 c-Fos 蛋白的表达。然而，在急性低血压后，这些大鼠的侧脑室脑室内微注射 MK-801 或 CNQX 后，双侧 MVN 中几乎没有表达 c-Fos 蛋白。这些结果表明，急性低血压时，来自外周前庭感受器的兴奋性传入信号将谷氨酸释放到前庭神经核中的突触后神经元中。这些兴奋性信号通过前庭系统中的 NMDA 受体和 AMPA 受体传递。
