Activation of striatal inflammatory mediators and caspase-3 is central to haloperidol-induced orofacial dyskinesia

The undesired extrapyramidal movement disorders observed with long term treatment with haloperidol have been associated with striatal neurodegeneration. The present study was designed to investigate the effect of prolonged haloperidol treatment on striatal levels of inflammatory mediators and caspase-3 and to correlate it with orofacial dyskinesia, a movement disorder observed with long term haloperidol treatment. Prolonged administration of haloperidol (1, 2, 5 mg/kg) to rats produced dose-dependent increase in the orofacial dyskinetic movements and induced a marked oxidative stress in the striatum. Lower dose of haloperidol (1 mg/kg) decreased NO levels but did not induce TNF-α or NF-κB expression. At higher doses (2 and 5 mg/kg), increased levels of total nitric oxide and TNF-α in cytoplasmic lysate and active p65 subunit of NF-κB in nuclear lysates of rat brain were observed. These doses (2 and 5 mg/kg) also induced an increased expression of caspase-3 protein in striatal cytoplasmic fraction as shown by western blot analysis. Collectively, we conclude that oxidative stress mediated increase in inflammatory mediators may initiate the apoptotic pathway (caspase-3) after chronic haloperidol treatment. All this is well correlated with behavioural development of orofacial dyskinesia.