Piperine in combination with quercetin halt 6-OHDA induced neurodegeneration in experimental rats: Biochemical and neurochemical evidences.

Parkinson's disease (PD) is a multifactorial neurological disorder caused by selective dopaminergic neuronal loss. Quercetin (QC) in combination with piperine (bioenhancer) acts as potential antioxidant, anti-inflammatory and neuroprotective against 6-OHDA rat model of PD. Rats were injected 6-OHDA (8μg/2μl, saline) unilaterally, intranigrally once into right SNpc. Pre-treatment with QC (25 and 50mg/kg, p.o.) alone and combination of QC (25mg/kg, p.o.) with piperine (2.5mg/kg, p.o.) were given for 14days starting from 8th day of 6-OHDA infusion. Post lesions were confirmed by rotational behavior with amphetamine (2.5mg/kg, i.p.) and motor coordination was assessed by narrow beam walk, open field and rotarod apparatus on the weekly basis. On 22nd day, animals were sacrificed and striatum homogenates were used for biochemical (LPO, GSH, Nitrite), neuroinflammatory (TNF-α, IL-1 β and IL-6) and neurotransmitter (dopamine, norepinephrine, serotonin, GABA, glutamate) analysis. Rats pre-treated with QC alone and in combination with piperine have significantly attenuated the 6-OHDA induced rotational behavior and motor deficits. Further, these drugs have significantly improved antioxidant potential, decreased striatal proinflammatory cytokines level as well as restored neurotransmitters level. The neuroprotective enhancement of QC along with piperine is attributed through antioxidant, anti-inflammatory and preventing neurotransmitter alteration mechanisms.