Abstract

The purpose of this study was to evaluate effect of MK801 or CNQX, glutamate receptor antagonist, on expression of pERK1/2 and cFos proteins induced by acute hypotension in the medial vestibular nucleus (MVN) of Sprague-Dawley rats. Acute hemorrhage with 4 ml loss of blood resulted in significant synthesis of pERK1/2 or cFos-like protein in the MVN in which the immunoreactivity for these proteins was much higher in the caudal MVN in rostral aspect. Single treatment of MK801, a NMDA receptor antagonist, resulted in complete suppression of pERK1/2 protein and cFos-like immunoreactive neurons in the MVN following acute hypotension. Furthermore, intraperitoneal injection of MK801 resulted in a marked reduction of transcriptional level of mitogen kinase phosphatse-1 mRNA that was increased in the vestibular nuclei 30 min after acute hemorrhage. Effect of systemic treatment of CNQX, a non-NMDA receptor antagonist was a similar with that of MK801 for expression of pERK1/2 protein, cFos protein and MKP-1 mRNA in the MVN following acute hypotension. These results suggest that glutamate receptors take part in activity-dependent expression of pERK1/2 and cFos proteins in the vestibular nuclear neurons following acute hypotension.(Supported by a grant of the Korea Health 21 R&D Project, Ministry of Health & Welfare(02-PJ1-PG3-21302-0010).