Abstract Anxiolytic effects of Garcinia lucida (G. lucida) barks aqueous extract and its possible action mechanisms were assessed in mice. Stress induced hyperthermia (SIH), Elevated plus maze (EPM), Open field (OF), and hole-board tests were used. Mice received distilled water as negative control, Phenobarbital (20 mg/kg) and diazepam (3 mg/kg) as positive control or gradual doses of G. lucida (200, 400 and 800 mg/kg) as test groups. After 24 hours acclimatization period, animals received appropriate treatment and 1 hour later individually subjected to behavioural paradigms and parameters recorded for 5 minutes. Involvement of GABAA receptor complex in G. lucida extract activity was inferred from experiments with known GABAA-targeting agents. Administration of G. lucida extract induced a significant (p˂0.05) decrease of SIH from 1.17°C to 1.03°C compared to negative control. In EPM test, open arms entries increased from 5.16±0.74(p˂0.01) to 8±0.57(p˂0.001) at 200 and 800 mg/kg respectively. In OF test, crossing number significantly (p˂0.001) increased from 74±11.66 to 92±8.53 respectively at 400 and 800 mg/kg. G. lucida significantly decreased rearing number from 22.16±1.044 (p˂0.05) at 200 mg/kg to 14.66±0.71 (p˂0.001) at dose 800 mg/kg, suggesting anxiolytic-like effects as observed with diazepam. These anxiolytic effects of G. lucida were significantly inhibited by anxiogenic activities of bicucilline (5 mg/kg), flumazenil (5 mg/kg) and N-methyl-β-carboline-3-carboxamide (10 mg/kg). Thus, G. lucida has anxiolytic properties that might be due to interactions with benzodiazepine-binding sites of GABAA receptor complex. These observed effects may in part explain the use of G. lucida in traditional medicine.
Keywords Mice, G. lucida, anxiety, anxiolyic, GABAA receptor complex.