Changes in GABAergic system parameters after chronic administration of bicuculline

Male Wistar rats were chronically treated with 2 mg/kg per day bicuculline i.p. during 10 days. Biochemical parameters related to the GABAergic system in CNS were analyzed. A 63% increase in glutamic acid decarboxylase activity was found in treated animals. Endogenous GABA levels were not modified. The treatment increased Bmax of GABA binding by 112% without changing the KD value. The treatment decreased Bmax of diazepam binding by 40% whereas it did not change the KD value. Diazepam binding was enhanced by in vitro addition of GABA at the same extent as in treated animals.