title: Effect of glutamate on the vestibulo-solitary projection after sodium nitroprusside-induced hypotension in conscious rats.
abstract: Orthostatic hypotension is most common in elderly people, and its prevalence increases with age. Attenuation of the vestibulo-sympathetic reflex (VSR) is commonly associated with orthostatic hypotension. In this study, we investigated the role of glutamate on the vestibulo-solitary projection of the VSR pathway to clarify the pathophysiology of orthostatic hypotension. Blood pressure and expression of both pERK and c-Fos protein were evaluated in the nucleus tractus solitarius (NTS) after microinjection of glutamate into the medial vestibular nucleus (MVN) in conscious rats with sodium nitroprusside (SNP)-induced hypotension that received baroreceptor unloading via sinoaortic denervation (SAD). SNP-induced hypotension increased the expression of both pERK and c-Fos protein in the NTS, which was abolished by pretreatment with glutamate receptor antagonists (MK801 or CNQX) in the MVN. Microinjection of glutamate receptor agonists (NMDA or AMPA) into the MVN increased the expression of both pERK and c-Fos protein in the NTS without causing changes in blood pressure. These results indicate that both NMDA and AMPA receptors play a significant role in the vestibulo-solitary projection of the VSR pathway for maintaining blood pressure, and that glutamatergic transmission in this projection might play a key role in the pathophysiology of orthostatic hypotension.
authors.affiliation: Department of Physiology and Pathophysiology, Yanbian University College of Medicine, Yanji 133002, China.
authors.forename: Li-Wei
authors.initials: LW
authors.lastname: Li
authors.affiliation: Department of Cerebral Surgery, Yanbian University College of Clinical Medicine, Yanji 133000, China.
authors.forename: Guang-Shi
authors.initials: GS
authors.lastname: Jin
authors.affiliation: Department of Physiology and Pathophysiology, Yanbian University College of Medicine, Yanji 133002, China.
authors.forename: Yan-Zhao
authors.initials: YZ
authors.lastname: Yang
authors.affiliation: Department of Physiology, Wonkwang University School of Medicine and Brain Science Institute at Wonkwang University, Iksan 570-749, Korea. ; University of Baghdad College of Medicine, Baghdad Medical City, Baghdad 10071, Iraq.
authors.forename: Abdul Nasir
authors.initials: AN
authors.lastname: Ameer
authors.affiliation: Department of Physiology, Wonkwang University School of Medicine and Brain Science Institute at Wonkwang University, Iksan 570-749, Korea.
authors.forename: Min Sun
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Department of Physiology, Wonkwang University School of Medicine and Brain Science Institute at Wonkwang University, Iksan 570-749, Korea.
authors.forename: Byung Rim
authors.initials: BR
authors.lastname: Park
authors.affiliation: Department of Physiology and Pathophysiology, Yanbian University College of Medicine, Yanji 133002, China.
authors.forename: Yuan-Zhe
authors.initials: YZ
authors.lastname: Jin
keywords: Glutamate; Nucleus tractus solitarius; Orthostatic hypotension; Vestibulosympathetic reflex; c-Fos protein