EFFECTS OF BETA-ADRENERGIC-RECEPTOR ANTAGONISTS ON NICOTINE-INDUCED TAIL-TREMOR IN RATS

The effects of various beta-adrenergic receptor antagonists on nicotin e-induced tail-tremor were investigated in rats. Atenolol (5 and 10 mg /kg, IP), arotinolol (5 and 10 mg/kg, IP), and carteolol (5 and 10 mg/ kg, IP), hydrophilic beta-adrenergic receptor antagonists, did not aff ect the tail-tremor induced by nicotine given at a dose of 0.5 mg/kg S C. However, propranolol (5-20 mg/kg, IP) and pindolol (5-20 mg/kg, IP) , nonselective and lipophilic beta-adrenergic receptor antagonists, di d suppress the tail-tremor dose dependently. In contrast, metoprolol ( 5-20 mg/kg, IP), lipophilic and beta1-selective adrenergic receptor an tagonists, did not show such an effect. These results suggest that nic otine-induced tail-tremors may be mediated through central beta2-adren ergic receptors as an appearance and developmental mechanism.