RESUMO
Injection of gamma butyric acid (GABA) into the lateral hypothalamic area of unrestrained conscious rats caused a decrease in renal electrolyte excretion with an increase in urinary flow. When picrotoxin, a specific inhibito of gabaergic pathways, was administered, a significant increase in renal water and electrolyte excretion occured. The effect of simultaneous injection of pidrotoxin and GABA into the same site indicate that picrotoxin was less potent in reversing tyhe effect induceb by GABA than GABA was in reversing the effect of picrotoxin. We conclude that GABA acts directly on the neuronal mechanisms involved in the control of water and elecltrolyte excretion, perhaps by exerting a tonic inhibitory action on renal electrolyte excretion
Assuntos
Animais , Ratos , Masculino , Ácido gama-Aminobutírico/antagonistas & inibidores , Picrotoxina/farmacologia , Região Hipotalâmica Lateral/fisiologia , Rim/metabolismo , Potássio/metabolismo , Ratos Wistar , Sódio/metabolismoRESUMO
Eletrical stimulation or microinjection of GABA antagonists into the dorsal periaqueductal gray (DPAG) produces escape behavior. In order to determine whether the nigrocollicular gabaergic fibers exert some control over this behavior, rats bearing kainic acid lesion of the substantia nigra pars reticulata were submitted to microinjections of bicuculline or electrical stimulation of the DPAG at the escape threshold. Rats thus treated exhibited a significant decrease in the escape threshold while bicuculline increased the expression of flight behavior. These results suggest an inhibitory control of gabaergic fibers from the substantia nigra pars reticulata on aversive behavior induced by DPAG stimulation