Evaluation of antinociceptive activity of Vanillin mediated through opioid receptors

Vanilla planifolia grown for its attractive aroma has rich medicinal value as evidenced by its antimutagenic, anti-invasive and anti-inflammatory activities. An analgesic activity mediated by opioid receptors has been suggested in earlier studies. Inbred adult wistar rats of either sex weighing 150-200grams were used for the study. Rats were randomly assigned to four groups [Control, morphine 2mg/kg, Vanillin 10mg/kg, Vanillin 100mg/kg] of six animals each. Eddy's hot plate method was used to evaluate analgesic activity. Naloxone pretreatment was employed to demonstrate any activity mediated through opioid receptors. There was significant increase (P<0.001) in latency period at 10mg/kg and 100 mg/kg doses of vanillin when compared to control. Naloxone pre-treatment significantly reduced the latency period in hot-plate test with both the doses of vanillin. Vanillin at a dose of 10 mg/kg and 100 mg/kg demonstrated a significant increase in latency period, displaying a potential central analgesic activity probably mediated through opioid receptors.