Protective effect of curcumin and its combination with piperine (bioavailability enhancer) against haloperidol-associated neurotoxicity: cellular and neurochemical evidence.

Long-term treatment with haloperidol is associated with a number of extrapyramidal side effects, particularly the irregular movements of chorionic type. This limitation presents a marked therapeutic challenge. The present study investigates the molecular etiology of haloperidol neurotoxicity and the role of curcumin, a well-known anti-oxidant, in ameliorating these adverse effects. The redox status of haloperidol-treated brains along with NO, TNF-α, NF-kappaB p65 subunit, caspase-3, and monoamine neurotransmitters were measured in the striatum of rat brain. Chronic treatment with haloperidol (5 mg/kg, i.p., 21 days) produced orofacial dyskinetic movements which were coupled with marked increase in oxidative stress parameters, TNF-α, caspase-3 activity in cytoplasmic lysate and active p65 sub unit of NF-kappaB in nuclear lysates of the striatum. Neurochemically, chronic administration of haloperidol resulted in a significant decrease in the levels of norepinephrine, dopamine, and serotonin. The prototype atypical anti-psychotic, clozapine (10 mg/kg, i.p., 21 days) produced mild oxidative stress but did not alter any other parameters. Interestingly, co-administration of curcumin (25 and 50 mg/kg, i.p., 21 days) dose-dependently prevented all the behavioral, cellular, and neurochemical changes associated with the chronic administration of haloperidol. Curcumin per se (50 mg/kg) did not show any side effects. Co-administration of piperine significantly enhanced the effect of curcumin (25 mg/kg) but not of curcumin (50 mg/kg). Collectively, the data indicated the potential of curcumin as an adjunct to haloperidol treatment and provided initial clues to the underlying molecular mechanisms in haloperidol neurotoxicity. This study also provides a rationale for the combination of piperine and curcumin.