Paeoniflorin attenuates neuroinflammation and dopaminergic neurodegeneration in the MPTP model of Parkinson's disease by activation of adenosine A1 receptor

1 This study examined whether Paeoniflorin (PF), the major active components of Chinese herb Paeoniae alba Radix, has neuroprotective effect in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease (PD). 2 Subcutaneous administration of PF (2.5 and 5 mg kg(-1)) for 11 days could protect tyrosine hydroxylase (TH)-positive substantia nigra neurons and striatal nerve fibers from death and bradykinesia induced by four-dose injection of MPTP (20 mg kg(-1)) on day 8. 3 When given at 1 h after the last dose of MPTP, and then administered once a day for the following 3 days, PF (2.5 and 5 mg kg(-1)) also significantly attenuated the dopaminergic neurodegeneration in a dose-dependent manner. Post-treatment with PF (5 mg kg(-1)) significantly attenuated MPTP-induced proinflammatory gene upregulation and microglial and astrocytic activation. 4 Pretreatment with 0.3 mg kg(-1) 8-cyclopentyl-1,3-dipropylxanthine, an adenosine A, receptor (AIAR) antagonist, 15 min before each dose of PF, reversed the neuroprotective and antineuroinflammatory effects of PF. 5 In conclusion, this study demonstrated that PF could reduce the MPTP-induced toxicity by inhibition of neuroinflammation by activation of the AIAR, and suggested that PF might be a valuable neuroprotective agent for the treatment of PD.