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Age‐dependent changes in cardiovascular responses induced by muscimol infused into the nucleus tractus solitarii and nucleus parabrachialis medialis in rats
Author(s) -
Mollace V.,
Francesco E.A.,
Fersini G.,
Nistico G.
Publication year - 1991
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1991.tb09866.x
Subject(s) - muscimol , bicuculline , microgram , bradycardia , medicine , endocrinology , nucleus , solitary nucleus , anesthesia , chemistry , heart rate , blood pressure , gabaa receptor , central nervous system , receptor , biochemistry , psychiatry , in vitro
1 The effects of muscimol and bicuculline on mean arterial blood pressure (MAP) and heart rate (HR) were studied after their microinfusion into the nucelus tractus solitarii (NTS) and into the nucleus parabrachialis medialis (NPBmed) in 3 and 24 month old rats. 2 In 3 month old rats a dose of 0.01 μg of muscimol given into the NTS increased MAP, whereas higher doses (0.05, 0.1 and 0.25 μg) produced dose‐dependent bradycardia with either no change (0.05 and 0.1 μg) or a decrease (0.25 μg) in MAP. 3 On the other hand, in 24 month old rats, the same doses of muscimol given into the NTS failed to change MAP, whereas in comparison to 3 month old rats they produced a significantly lesser bradycardia. 4 The cardiovascular changes elicited by infusion of muscimol into the NTS in 3 and 24 month old rats were prevented by prior microinfusion of bicuculline into the same site. 5 Muscimol given into the NPBmed in doses from 0.05 to 0.25 μg produced, in 3 month old rats dose‐dependent decreases in MAP and HR which were prevented by prior administration of bicuculline. These effects were significantly reduced in 24 month old rats. 6 The present experiments show that with aging there is impairment of GABA‐ergic mechanisms involved in the regulation of cardiovascular activity in the NTS and NPBmed.