Influence of hyper-and hypothyroidism on body temperature and brain amphetamine and norepinephrine levels of amphetamine-treated rats

Abstract

Influence of hyper-and hypothyroidism on amphetamine activity was observed by measuring the effects of hyperthermia and brain amphetamine and norepinephrine levels. Hyperthyroidism was obtained in rats injected with triiodothyronine 0.2 mg/kg i.p. every day for 5 days. Controls were treated with the vehicle 1.0 ml/kg i.p. for the same period. On the 6th day d-amphetamine (10 mg/kg i.p.) was administered to the 2 groups of animals, and the body temperature and brain amphetamine and norepinephrine contents were measured at 0, 15, 30, and 60 min. Hyperthyroid rats showed a more marked hyperthermia than did the control animals. Amphetamine-induced release of norepinephrine of hyperthyroid rats was not so marked as in the control rats, however, amphetamine levels did not differ in the 2 groups. Hypothyroidism was evident in the thyroidectomized rats. Controls for this group underwent a sham-operation. All animals were injected with amphetamine 21 days later. Amphetamine did not cause a hyperthermia in thyroidectomized rats. Amphetamine levels were considerably higher than in control rats, but the degree of norepinephrine release was comparable in the 2 groups.