Effects of the hook of Uncaria rhynchophylla on neurotoxicity in the 6-hydroxydopamine model of Parkinson's disease.

Ethnopharmacological Relevance: While the hook of Uncaria rhynchophylla (URH) is a traditional herb used in northeast Asia for the treatment of Parkinson's disease (PD)-like symptoms such as tremor, it has not been experimentally evaluated in a PD model.

Aim Of The Study: We investigated the effects of URH on 6-hydroxydapamine (6-OHDA)-induced neurotoxicity in in vitro and in vivo models of PD.

Materials And Methods: The cell viability, anti-oxidative activity, and anti-apoptotic activity of a water extract of URH (URE) were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide, reactive oxygen species (ROS), total glutathione (GSH), and caspase-3 assays in PC12 cells stressed by 6-OHDA. We also investigated the behavioral recovery and dopaminergic neuron protection of URE using an apomorphine-induced rotation test and tyrosine hydroxylase immunohistochemistry in the hemi-parkinsonian rat model of the unilateral 6-OHDA lesion of the medial forebrain bundle.

Results: In PC12 cells, URE significantly reduced cell death and the generation of ROS, increased GSH levels, and inhibited caspase-3 activity induced by 6-OHDA. In 6-OHDA-lesioned rats, posttreatment with URE (5 mg/kg/day for 14 days) significantly reduced apomorphine-induced rotation, and it lowered dopaminergic neuronal loss in substantia nigra pars compacta.

Conclusions: URE possesses neuroprotective activity against 6-OHDA-induced toxicity through anti-oxidative and anti-apoptotic activities in PD models.