Effect of drugs influencing synthesis of prostaglandins on haloperidol-induced catalepsy in rats.

Rats pretreated with prostaglandin synthesis stimulators, phenoxymethyl penicillin (2, 4 and 8 mg/kg, ip) and levamisole (2.5, 5 and 10 mg/kg, ip) showed a dose related potentiation of catalepsy after subthreshold doses of haloperidol (0.1 mg/kg, ip). Pretreatment with prostaglandin synthesis inhibitors paracetamol and indomethacin exhibited significant inhibition of catalepsy at lower doses (2.5, 6, 10 and 15 mg/kg, ip). However, this antagonism was paradoxically less at higher dose levels (20 and 30 mg/kg, ip). The data suggest neuromodulatory contribution of prostaglandins in neuroleptic-induced catalepsy.