BACLOFEN-INDUCED CATATONIA - MODIFICATION BY SEROTONERGIC AGENTS

Baclofen, a GABA(B) receptor agonist can induce catatonia in rats. Thi s catatonia may serve as a tool for the study of GABA(B) receptor func tion. Reciprocal interactions between serotonin (5-HT) and GABA(B) rec eptors in the CNS are known to occur. In the present study we examined the effects of various agents that influence serotonergic neurotransm ission on baclofen-induced catatonia in rats. The catatonia was rated by means of a scoring method, according to the severity of motor sympt oms produced by baclofen (10-15 mg/kg, i.p.). All serotonergic drugs w ere injected intraperitoneally 30 min prior to baclofen, except the 5- HT synthesis inhibitor p-chlorophenylalanine (PCPA), which was injecte d 72 and 48 hr prior to baclofen. The 5-HT releaser fenfluramine (10 m g/kg) and the uptake inhibitor fluoxetine (10 mg/kg) reversed, whereas the 5-HT1A agonist buspirone (3 mg/kg) potentiated baclofen-induced c atatonia. The 5-HT synthesis inhibitor PCPA (150 x 2 mg/kg), the non-s pecific 5-HT antagonist cyproheptadine (5 mg/kg), the 5-HT1A/1B antago nist pindolol (3 mg/kg) and the 5-HT2 antagonist sulpiride (20 mg/kg) enhanced baclofen-induced catatonia. It is concluded that the manipula tions of central serotonergic mechanisms modulate baclofen-induced cat atonia. Copyright (C) 1996 Elsevier Science Ltd.