Neuroprotective effect of Valeriana wallichii rhizome extract against the neurotoxin MPTP in C57BL/6 mice

Abstract

Oxidative stress and inflammation are some of the contributing factors for dopaminergic neurodegeneration in Parkinson's disease (PD). Though Valeriana wallichii D.C. is known for its nervine activities its effect against PD is yet to be studied. This is the first report on the antioxidant and anti-inflammatory effect of V. wallichii rhizome extract (VWE) in MPTP induced PD mice. GC–MS analysis of VWE indicated the presence of phytoconstituents like isovaleric acid and acacetin. PD induced mice were treated orally with three different doses (50, 100 and 200mg/kg body weight (BW)) of VWE for 14 days and their behavioural changes were studied on days 0, 8, 13 and 21. The levels of striatal dopamine, mid brain tyrosine hydroxylase positive (TH+) cell count, TH protein expression, reactive oxygen species (ROS), lipid peroxidation (LPO), antioxidants and inflammatory cytokines were analysed. Mid brain glial fibrillary acidic protein (GFAP) expression was assessed by immunohistochemistry and western blotting. Also mid brain histopathological analysis was performed. VWE treatment significantly recuperated the altered behavioural test scores, striatal dopamine levels, mid brain TH+ cell count and TH protein levels, increased GFAP expression and the histopathological changes observed in PD mice. Similarly, diminished levels of antioxidants, elevated levels of ROS, LPO and inflammatory cytokines were also significantly ameliorated following VWE treatment. The effective dose of VWE was found to be 200mg/kg BW. Conclusively, V. wallichii rhizome extract has the potential to mitigate oxidative stress and inflammatory damage in PD.