Vinpocetine prevents rotenone-induced Parkinson disease motor and non-motor symptoms through attenuation of oxidative stress, neuroinflammation and α-synuclein expressions in rats

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by motor and non-motor symptoms. Epidemiological reports showed a significant association between environmental toxicants-induced gut dysbiosis and PD. Neuroinflammation, mitochondrial dysfunction and decreased cerebral blood flow are hallmarks of PD. This study sought to evaluate the protective ability of vinpocetine (VIN), a neuroprotectant, on rotenone (ROT) (mitochondrial complex I inhibitor) induced PD in rats. Sixty male Sprague Dawley rats were randomly divided into six groups (n = 10) and treated orally as follows; group 1: vehicle (10 ml/kg); group 2: rotenone (10 mg/kg) + vehicle; group 3-5: vinpocetine (5, 10 or 20 mg/kg) + rotenone (10 mg/kg), respectively, or group 6: vinpocetine 20 mg/kg before behavioural assay for motor symptoms (fore-limb hanging test and open field test) and non-motor symptoms (working memory and learning capabilities in Y-maze/Morris water maze tasks, anxiety in hole board test and gut motility with intestinal transit time). Following treatment for 28 days, biochemical assays and immunostaining was performed. We examined the effect of vinpocetine on rotenone-induced oxidative stress and inflammatory markers. The pretreatment of rats with vinpocetine reversed rotenone-induced locomotor deficit, motor incoordination, cognition deficits and gut dysfunction. In addition, rotenone-induced a significant increase in the level of interleukin-6 and tumor necrotic factor-α, oxidative stress markers, cholinergic signalling, gut dysfunction and haematologic dysfunctions which were attenuated by vinpocetine administration. Immunostainings showed that rotenone-induced dopamine neuron loss, microglia reactivity, astrocytes activation, toll-like receptor 4 (TLR4) and α-synuclein (SNCA) expressions which were attenuated by vinpocetine administration. Findings from this study revealed a neuroprotective effect of vinpocetine on rotenone-induced PD through anti-neuroinflammatory and antioxidant mechanisms.