Cardiovascular effects of acetylcholine microinjection into the ventrolateral and dorsal periaqueductal gray of rats.
In the present study, we describe the cardiovascular effects of local acetylcholine (Ach) microinjection into both the ventrolateral (vlPAG) and dorsal (dPAG) periaqueductal gray areas of anesthetized rats and the possible local receptors involved with these responses. Microinjection of Ach (9, 27, 45 or 81 nmol/50 nL) into the vlPAG caused dose-related depressor responses. These hypotensive responses were blocked by local pretreatment with increasing doses of the nonselective muscarinic antagonist atropine (1, 3 or 9 nmol/50 nL)(.) The microinjection of Ach into the dPAG caused no significant cardiovascular responses in anesthetized rats. In conclusion, the present findings suggest that a cholinergic system present in the vlPAG, but not in the dPAG, is involved with cardiovascular system control. Moreover, these cardiovascular responses evoked by Ach are mediated by muscarinic receptors.
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, São Paulo 14040-900, Brazil.
Milena Vieira
MV
Deolindo
Gislaine Garcia
GG
Pelosi
Cristiane
C
Busnardo
Leonardo Barbosa Moraes
LB
Resstel
Fernando Morgan Aguiar
FM
Corrêa
D000109:Acetylcholine / Q000494:pharmacology* / Q000633:toxicity; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D002799:Cholinergic Fibers / Q000648:ultrastructure; D006339:Heart Rate / Q000187:drug effects*; D007022:Hypotension / Q000139:chemically induced; D008297:Male; D008845:Microinjections; D010487:Periaqueductal Gray / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
D001285:Atropine; D000109:Acetylcholine