Cardiovascular responses to glutamate microinjection in the dorsomedial periaqueductal gray of unanesthetized rats.

Abstract	The periaqueductal gray area (PAG) is a mesencephalic area involved in cardiovascular modulation. Glutamate (L-Glu) is an abundant excitatory amino acid in the central nervous system (CNS) and is present in the rat PAG. Moreover, data in the literature indicate its involvement in central blood pressure control. Here we report on the cardiovascular effects caused by microinjection of L-Glu into the dorsomedial PAG (dmPAG) of rats and the glutamatergic receptors as well as the peripheral mechanism involved in their mediation. The microinjection of L-Glu into the dmPAG of unanesthetized rats evoked dose-related pressor and bradycardiac responses. The cardiovascular response was significantly reduced by pretreatment of the dmPAG with a glutamatergic M-methyl-D-aspartate (NMDA) receptor antagonist (LY235959) and was not affected by pretreatment with a non-NMDA receptor antagonist (NBQX), suggesting a mediation of that response by the activation of NMDA receptors. Furthermore, the pressor response was blocked by pretreatment with the ganglion blocker pentolinium (5 mg/kg, intravenously), suggesting an involvement of the sympathetic nervous system in this response. Our results indicate that the microinjection of L-Glu into the dmPAG causes sympathetic-mediated pressor responses in unanesthetized rats, which are mediated by glutamatergic NMDA receptors in the dmPAG.
Authors	Gislaine Garcia Pelosi, Cristiane Busnardo, Rodrigo Fiacadori Tavares, Fernando Morgan Aguiar Corrêa
Journal	Journal of neuroscience research (J Neurosci Res) Vol. 90 Issue 11 Pg. 2193-200 (Nov 2012) ISSN: 1097-4547 [Electronic] United States
PMID	22715034 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Copyright	Copyright © 2012 Wiley Periodicals, Inc.
Chemical References	Glutamic Acid
Topics	Animals Blood Pressure (drug effects) Cardiovascular System (drug effects) Dose-Response Relationship, Drug Glutamic Acid (administration & dosage) Heart Rate (drug effects) Male Microinjections Periaqueductal Gray (drug effects) Rats Rats, Wistar

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