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Modification of reserpine-induced emetic response in pigeons by alpha 2-adrenoceptors
S K Khandker1, D Mukerjee, S Gurtu
1Department of Pharmacology and Therapeutics, King George's Medical College, Lucknow, India.
Abstract:
In the present study, an attempt has been made to elucidate the role of alpha 2-adrenoceptors in reserpine-induced emesis in pigeons. Reserpine was found to induce dose-dependent emesis and a 500 micrograms kg-1 dose was found to be the 100% emetic dose. alpha 2-adrenoceptor agonists clonidine and alpha-methylnoradrenaline inhibited the reserpine induced emesis. Out of the two selective alpha 2-adrenoceptor antagonists idazoxan and yohimbine, only the latter induced a dose-dependent emesis. However, both the drugs potentiated reserpine-induced emesis and antagonised its inhibition by clonidine. Prior depletion of monoamines by reserpine also blocked the emetic response of reserpine. These observations indicate that release of monoamines is responsible for its emetic response in pigeons which is modulated by presynaptic alpha 2-adrenoceptors in a predictable manner.