Effect of imipramine or ECS on central β1 and β2 receptor sensitivity in the cardiovascular response of ratreceptor sensitivity in the cardiovascular response of rat

Abstract

This study was investigated the effects of imipramine (IMI) and electroconvulsive shock (ECS), which are used as antidepressant therapy, on the central β1- or β2 adrenergic receptor in anesthetized rats. The resting blood pressure and heart rate decreased in reserpinized group (5 mg/kg i.p., 24 hr before), but not in other 4 groupsi.e. acute IMI (20 mg/kg i.p. 3–5 hr before), chronic IMI (Same dose, twice a day for 14 days), single ECS (sinusoidal 20 Hz, 120 V for 1 sec) and repeated ECS (same condition, daily for 12 days). The increase of heart rate and hypotension evoked by 1 or 3 μg intracerebroventricular (i.c.v.) administration of (+)dobutamine, β1-agonist, was attenuated by chronic IMI treatment. The hypotension by salbutamol, β2-agonist, 1 or 3μg i.c.v. was significantly attenuatted in repeated ECS or reserpine treatment. And, the diminution of pulse pressure of salbutamol also reduced by repeated ECS. These results suggest that IMI or ECS result in attenuation on tachycardia by (+)dobutamine or on hypotension by salbutamol, presumably by which the central β1 or β2-receptor sensitivity may be suppressed, respectively.