[Changes of heme oxygenase-1 expression in the nigrostriatal system of MPTP-treated SAMP8 mouse].

AIM: To explore the relationship between the expression of hemeoxygenase-1 (HO-1) and the dopaminergic system impairment in MPTP-treated SAMP8 mice. METHODS: 6-month-old male SAMP8 mice received MPTP (20 mg/kg) subcutaneous injection at 2-h intervals for 4 times, and the control group was treated with an equal volume of normal saline. Mice were sacrificed at 6 h, 24 h, 3 d and 8 d after the first injection for the detection of the changes of tyrosine hydroxylase (TH) and HO-1 in the nigrostriatal system by immunohistochemistry and Western blotting. RESULTS: TH-positive neuronal loss was visible at 6 h (14.23%, P<0.05), 24 h (23.85%, P<0.01), 3 d (36.77%, P<0.001), and 8 d (45.90%, P<0.001), and the significant progression of dopaminergic neuronal loss occurred most prominently in the MPTP group from 24 h to 3 d (24 h vs 3 d, P<0.05). There was a significant decrease of striatal TH immunoreactive cells in the MPTP group (P<0.05). Additionally, HO-1 positive cells were detected in striatum just only at 3 d, with the increase of HO-1 protein expression in MPTP groups. Western blot analysis showed no change of HO-1 protein levels in the midbrain after MPTP treatment compared to those of the normal saline group. CONCLUSION: MPTP caused the loss of dopaminergic neuron number and the decrease of TH protein levels in SAMP8 mice. The up-regulation of HO-1 was ephemeral, and its effects related with Parkinson's disease was limited in this study.