Background: Ginkgo biloba extract (GbE) is known to contain several bioactive compounds and exhibits free radical scavenging activity. Parkinson's Disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons and is associated with oxidative stress, neuroinflammation and apoptosis.

Objective: The current study aimed to investigate the neuroprotective effect of GbE in a rat model of PD induced by rotenone (ROT; a neurotoxin).

Methods: Twenty-four male albino rats were randomly divided into four groups of six rats each: normal control, GbE treated, toxin control (ROT treated) and GbE+ROT group.

Results: Oral administration of ROT (2.5 mg/kg b.w.) for 50 days caused an increased generation of lipid peroxidation products and significant depletion of reduced glutathione, total thiol content and activities of enzymatic antioxidants, i.e., superoxide dismutase and glutathione peroxidase in the brains of treated rats. Furthermore, ROT caused an elevation in acetylcholinesterase, interleukin-1β, interleukin- 6 and tumor necrosis factor-α and a significant reduction in dopamine in the stratum and substantia nigra. Immunohistochemical results illustrated that ROT treatment reduced the expression of tyrosine hydroxylase (TH). GbE treatment (150 mg/kg b.w./day) significantly reduced the elevated oxidative stress markers and proinflammatory cytokines and restored the reduced antioxidant enzyme activities, DA level and TH expression. These results were confirmed by histological observations that clearly indicated a neuroprotective effect of GbE against ROT-induced PD.

Conclusion: GbE mitigated ROT-induced PD via the inhibition of free-radical production, scavenging of ROS, and antioxidant enhancement.

Keywords: Ginkgo biloba; Parkinson's disease; ROT treatment; neuroprotection; oxidative stress; rotenone.