Involvement of bicuculline-insensitive receptors in the hypothermic effect of GABA and its agonists.

GABA, delta-aminovaleric acid (DAVA) and sodium valproate (VPA) decrease core temperature in conscious rats. Bicuculline increases GABA-induced hypothermia, does not modify DAVA (250 mg/kg) and VPA (100 and 400 mg/kg) hypothermia and antagonizes initial hypothermia by DAVA (1000 mg/kg) and VPA (200 mg/kg) and late hypothermia by DAVA (500 mg/kg) and VPA (200 mg/kg). Picrotoxin increases late hypothermia by GABA (250 mg/kg) and VPA (400 mg/kg), but decreases initial hypothermia by VPA (200 mg/kg). Pentylenetetrazol increases variably GABA-induced hypothermia, inhibits early early hypothermia by DAVA and increases hypothermia induced by VPA (400 mg/kg). We conclude that GABA and GABA-agonists (DAVA and VPA) may induce hypothermia partly mediated by activation of bicuculline-insensitive GABA-receptors.