Effects of adrenoceptor blockers on the glycemic response to nicotine in thyroidectomised rats

Abstract

The effect of adrenoceptor blockers on nicotine-induced hyperglycemia was studied in fasted normal and thyroidectomized rats. Blood glucose was estimated using the modified glucose oxidase method. The control experiments consisted of sham-operated rats with intact thyroid glands. Pre-treatment of the rats with either the alpha-adrenoceptor blocker prazosin or the beta-adrenoceptor blocker propranolol before intravenous injection of nicotine (50 ng/kg) significantly reduced the hyperglycemia induced by nicotine in normal rats, while a combination of propranolol and prazosin abolished nicotine-induced hyperglycemia. In the thyroidectomized group, nicotine also caused hyperglycemia. However, the basal glucose level and a peak of glycemic response were lowered compared to that in the control group. The results therefore seem to suggest that both alpha and beta-adrenoceptors are involved in nicotine-induced hyperglycemia in the rat