The ventrolateral periaqueductal gray is involved in the cardiovascular response evoked by l-glutamate microinjection into the lateral hypothalamus of anesthetized rats.
Microinjection of l-glutamate (l-glu: 1, 3, 10 and 30nmol/100nL) into the lateral hypothalamus (LH) caused dose-related depressor and bradycardiac responses. The cardiovascular response to l-glu stimulation of the LH was blocked by pretreatment of the ventrolateral portion of the periaqueductal gray matter (vlPAG) with CoCl2 (1mM/100nL), indicating the existence of a synaptic relay of the hypotensive pathway in that area. Furthermore, the response to l-glu was blocked by pretreatment of the vlPAG with 2nmol/100nL of the selective NMDA-receptor antagonist LY235959 and was not affected by pretreatment with 2nmol/100nL of the selective non-NMDA-receptor antagonist NBQX, suggesting a mediation of the hypotensive response by NMDA receptors in the vlPAG. In conclusion, our results indicate that the hypotensive pathway activated by microinjection of l-glu into the LH involves a NMDA synaptic relay in the vlPAG.
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Avenue Bandeirantes 3900, CEP: 14049-900, Ribeirão Preto, São Paulo, Brazil.
Milena
M
Deolindo
Gislaine Garcia
GG
Pelosi
Rodrigo Fiacadori
RF
Tavares
Fernando Morgan
FM
Aguiar Corrêa
D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D003035:Cobalt / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects*; D007026:Hypothalamic Area, Lateral / Q000187:drug effects*; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D008845:Microinjections / Q000379:methods; D009407:Nerve Block / Q000295:instrumentation; D010487:Periaqueductal Gray / Q000187:drug effects / Q000502:physiology*; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D018691:Excitatory Amino Acid Antagonists; D007546:Isoquinolines; D011810:Quinoxalines; C062865:2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline; D003035:Cobalt; D018698:Glutamic Acid; C088643:LY 235959; C018021:cobaltous chloride