Potential mechanisms of neuroprotection induced by low dose total-body γ-irradiation in C57 mice administered with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)

Low dose total-body γ-irradiation (TBI) was reported to confer neuroprotection against MPTP-induced dopaminergic neurotoxicity. After being pretreated with a single low dose (0.5 Gy, 2.0 Gy or 3.5 Gy) TBI, C57BL/6 mice were administered with MPTP (15 mg/kg, four times, 2 h apart) intraperitoneally (i.p.). In the group pretreated with 2.0 Gy TBI, with lower lymphocytes number, neuroprotection was found by High Performance Liquid Chromatography (HPLC) determination of the striatal dopamine. Contrarily, in the group pretreated with 0.5 Gy TBI, with higher lymphocytes number, dopaminergic neuron toxicity was enhanced. So it was probably the decrease of lymphocytes, not the radiation hormesis that rendered the potential neuroprotection. And it was the balance between radiation injury and lymphocytopenia neuroprotection that decided the effect of low dose γ-irradiation on MPTP-induced dopaminergic neurotoxicity.