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Objectives: Parkinson’s disease (PD) is the most prevalent movement disorder. Available therapies are palliative with no effect on disease progression. We have previously demonstrated that kolaviron (KV), a natural anti-inflammatory and antioxidant agent, suppressed behavioral defect, redo-inflammation, and nigrostriatal pathology in rotenone PD model. The present study investigates the neuroprotective effect of KV focusing on DJ-1/nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. Material and Methods: All-trans retinoic acid (ATRA, 10 mg/kg/day) was used to inhibit Nrf2. PD was established with four doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (20 mg/kg) at 2 h interval. MPTP mice were pre-treated with either KV (200 mg/kg/day), ATRA or both for 7 days before MPTP. Mice were evaluated for locomotor defects and indices of oxidative stress, neuroinflammation and neurotransmission as well as pathological tyrosine hydroxylase expression PD were evaluated in the striatum. Results: ATRA alone in mice did not exhibit neurobehavioral defect but caused striatal toxicity, mild nigrostriatal pathology, significant nitrosative stress, and Nrf2 cascade inhibition. KV+ATRA mice were slow in movement with frequent short-lived interruptions and oxidative striatal pathology. ATRA aggravated MPTP-associated locomotor incompetence and could not prevent nigrostriatal toxicity with evident vacuolated striosome and pyknotic/degenerating dopaminergic neurons. MPTP induced acute locomotor, exploratory, and motor incompetence, which was prevented by KV treatment. In addition, KV treatment restored MPTP-mediated depletion of endogenous antioxidant, striatal nitrosative stress, and oxidative damage with elevated DJ-1 level, potentiated Nrf2/NAD(P)H; quinone oxidoreductase-1 cytoprotective capacity, reduced Kelch-like ECH-associated protein 1 expression, and limited striatal pathology. However, ATRA treatment attenuated all the protective effects of KV on MPTP-challenged mice. Meanwhile, other ATRA-combinations elicited significant DJ-1 and Nrf2 induction but are associated striatal toxicity/pathology. Conclusion: This suggests that KV may be conferring protection through a yet-undetermined DJ-1 downstream cytoprotective effect dependent on the KV-mediated attenuation of oxidative environment. |
