The effects of alpha-pinene on anxiety behaviours and TLR4/MYD88/NF-kB pathway in the hippocampus in the reserpine-induced anxiety model in rats.

Abstract

OBJECTIVE: Anxiety disorders are prevalent neuropsychiatric conditions associated with neuroinflammation and altered cytokine signalling in the hippocampus. This study aimed to evaluate the anxiolytic-like effects of alpha-pinene and its potential modulation of hippocampal neuroinflammatory pathways in a reserpine-induced anxiety model. METHODS: Adult male Wistar rats were randomly assigned to four groups: control (vehicle), reserpine (0.5 mg/kg, i.p.), and reserpine co-treated with alpha-pinene at 50 or 100 mg/kg. Treatments were administered intraperitoneally for 10 consecutive days. Behavioural assays – including the Open Field Test, Elevated Plus Maze, and Light/Dark Box Test – assessed locomotor activity and anxiety-like behaviours. Following testing, hippocampal tissues were collected for molecular analyses, including real-time PCR for TLR4, MyD88, and NF-κB expression, and ELISA quantification of IL-1β and IL-6 levels. RESULTS: Reserpine induced robust anxiety-like behaviours, accompanied by significant upregulation of TLR4, MyD88, and NF-κB expression and increased hippocampal IL-1β and IL-6. Alpha-pinene treatment at both doses significantly attenuated anxiety-like behaviours and reduced neuroinflammatory markers, suggesting involvement of the TLR4/MyD88/NF-κB pathway. CONCLUSION: Alpha-pinene exhibits anxiolytic-like effects in reserpine-treated rats, potentially via suppression of hippocampal neuroinflammation, supporting further investigation into its therapeutic potential for anxiety disorders.