OBJECTIVETo examine the protective effect of nicotinamide on 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) in mouse model and its mechanisms.

METHODSParkinson's disease was induced by injection of MPTP in adult male C57BL/6 mice, nicotinamide (500 mg/kg,i.p.) was given prior to subacute (30 mg/kg/d × 5 d,i.p.) MPTP administration. Locomotor activities, striatal dopamine levels, lactate dehydrogenase (LDH) and NO synthase (NOS) activities of whole brains and striatum were analyzed at d5 after last MPTP injections.

RESULTSPretreatment with nicotinamide significantly improved the locomotor activity in the open-field test (P<0.01), but not in the swimming test and grip & climbing test. Nicotinamide administration resulted in sparing striatal dopamine levels from MPTP-induced dopamine depletion. There was no significant difference in LDH and NOS activities in the whole brains among the groups; but the activities in the striatum were drastically elevated after MPTP treatment. Nicotinamide pretreatment markedly inhibited MPTP-induced LDH and NOS activities (P<0.01) and showed no significant difference compared to controls (P>0.05).

CONCLUSIONNicotinamide protects dopaminergic neurons against MPTP-induced neurodegeneration,which suggests that the neuroprotective effects be associated with the inhibition of cell injuries and NOS activities.