Neuroprotective effects of piperine, an alkaloid from the Piper genus, on the Parkinson's disease model in rats

Abstract

Piperine (PIP), an alkaloid from the Piper genus plants, presents biological properties, including potent anti-inflammatory actions. Since neuroinflammation plays a key role in Parkinson's disease (PD), the objectives were to evaluate the neuroprotective activity of PIP in a model of PD. Male Wistar rats were divided as: sham-operated (SO), untreated 6-OHDA (lesioned in the right striatum) and 6-OHDA lesioned and treated orally with PIP (5 and 10 mg/kg, 2 weeks). The SO group was injected with saline into the right striatum. The SO and untreated 6-OHDA groups were administered with water, for 2 weeks. All animals were subjected to behavioral (open field, rotarod, and apomorphine-induced rotations tests), neurochemical (DA and DOPAC determinations), histological (fluoro jade staining) and immunohistochemical analyses (TH, DAT, TNF-alpha and iNOS). The results showed that PIP reversed behavioral alterations observed in the untreated 6-OHDA group. DA and DOPAC contents decreased in the striatal lesioned side of the untreated 6-OHDA group, but this change was in part reversed by PIP, at the higher dose. The fluoro jade fluorescence, observed in the untreated 6-OHDA group was attenuated after PIP treatments. Furthermore, increased immunoreactivities for TH and DAT were completely reversed in the lesioned group after PIP treatments. In addition, a partial recovery of increased striatal immunoreactivies for TNF-alpha and iNOS was observed in the lesioned group after PIP treatments. In conclusion, PIP presented a neuroprotective action, probably a consequence of its anti- inflammatory and antioxidant properties, making the drug a potential candidate for the treatment of neurodegenerative diseases as PD.