Resveratrol synergizes with low doses of L-DOPA to improve MPTP-induced Parkinson disease in mice

L-DOPA (L-3,4-dihydroxyphenylalanine) relieves symptoms of Parkinson disease (PD), but long-term use can cause serious side effects. Resveratrol (3,5,4'-trihydroxy-trans-stilbene, RV), a polyphenolic compound derived from grapes and red wine that has antioxidant activity, has been shown to have neuroprotective effects. RV was investigated to enhance the therapeutic effect of L-DOPA in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mouse model of Parkinson disease. Mice received a saline or RV injection (10 mg/kg/day), then 2 h later, saline or MPTP (15 mg/kg/day) was administered for 7 consecutive days. Saline or L-DOPA (5 or 8 mg/kg/day) was injected post-administration of MPTP for the last 2 consecutive days. Our results indicated that RV alleviated MPTP-induced loss of dopaminergic neurons and attenuated astroglial activation in the nigrostriatal pathway. In parallel, RV reduced the expression of a-synuclein in the striatum. In addition, RV also increased levels of the anti-apoptotic signalling molecule Bcl-2, reduced levels of the pro-apoptotic signalling molecule Bax, and reduced activation of caspase-3 in the striatum. Specifically, RV significantly reduced motor dysfunction in MPTP-treated mice. Furthermore, the RV-treated group showed less IL-beta and an enhanced pAkt/Akt ratio, which promoted dopamine neuron survival in the striatum. We found that the effects of co-administration of RV with L-DOPA (5 mg/kg) were equivalent to those of administration of 8 mg/kg L-DOPA in MPTP-induced PD mice. Therefore, with fewer side effects, L-DOPA can be effectively used in the treatment of PD over a long period of time.