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Cardiovascular responses to glutamate microinjection in the dorsomedial periaqueductal gray of unanesthetized rats
Author(s) -
Pelosi Gislaine Garcia,
Busnardo Cristiane,
Tavares Rodrigo Fiacadori,
Corrêa Fernando Morgan Aguiar
Publication year - 2012
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.23094
Subject(s) - microinjection , glutamatergic , nmda receptor , periaqueductal gray , glutamate receptor , endocrinology , medicine , central nervous system , nbqx , chemistry , receptor antagonist , antagonist , receptor , neuroscience , pharmacology , ampa receptor , biology , midbrain
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. © 2012 Wiley Periodicals, Inc.