Turmeric active substance, curcumin, enhanced apomorphine-induced yawning in rats

Abstract

Objective: Curcumin is a major constituent of turmeric and influences many functions of the brain. In the present study, we investigated the effect of curcumin on yawning induced by apomorphine in rats. <br/>Materials and Methods: Curcumin administered orallyfor 10 consecutive days. Yawning was induced by subcutaneous (s.c.) injection of apomorphine (a dopamine receptor agonist) and the number of yawns was recorded for a period of 30 min. <br/>Results: Apomorphine (0.05 and 0.1 mg/kg) produced yawning. Haloperidol (a dopamine receptors antagonist) at a dose of 0.05 mg/kg partially and at a dose of 0.2 mg/kg completely inhibited apomorphine-induced yawning. Curcumin alone produced no yawning, whereas at doses of 30 and 60 mg/kg, it increased yawning induced by 0.1 mg/kg of apomorphine. Curcumin at the high doses (30 and 60 mg/kg) produced yawning when apomorphine (0.1 mg/kg) action was partially blocked with 0.5 mg/kg of haloperidol. In the presence of complete blockade of apomorphine (0.1 mg/kg) action with 0.2 mg/kg of haloperidol, curcumin did not produce yawning. <br/>Conclusion: The results showed that curcumin at high doses increased apomorphine-induced yawning. In the presence of partial, but not complete blockade of apomorphine action, curcumin produced yawning. Curcumin produced a dopamine-like effect on yawning.