Effects of Gabaa-active Agents on Thermoregulataion in Rats

PURPOSE: Gamma-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter, which is widely distributed throughout the mammalian brain including hypothalamus. Immunohistochemical research have reported GABA-ergic neurons and GABAA-receptors on the neurons of the preoptic area of anterior hypothalamus (PO/AH). The aim of this study was to investigate the influence of GABAAergic substances on thermoregulation in rats. METHODS: We have studied the effects of GABAAactive agents, muscimol and diazepam on core body temperature in rats after systemic administration (intraperitoneally, i.p.). Body temperature was measured with thermistor probes (TX8) and monitored on multichannel recorder THERMEX 16. RESULTS: Intraperitoneal injection of muscimol or diazepam has produced dose-dependent hypothermia. Hypothermic effect of muscimol was inhibited by pretreatment of bicuculline, a competitive antagonist of GABAA-receptors. Diazepam induced hypothermia was antagonized by pretreatment of animals with flumazenil, a competitive antagonist of benzodiazepine receptors. CONCLUSION: Hypothermia induced by muscimol or diazepam suggest involvement of GABAA receptors in the processes of thermoregulation.