Interactions of adrenergic stimulants and blockers on self-stimulation behavior in rats

Self-stimulation behavior in rats was facilitated by two adrenergic stimulants, amphetamine (0.5 or 1 mg/kg, intraperitoneal, i.p., or 100 mug, intracerebroventricular, i.c.v.) and cocaine (5 mg/kg, i.p.). Three alpha-adrenergic blockers (phenoxybenzamine, dibenamine, phentolamine) and a beta-adrenergic blocker (propranolol) decreased self-stimulation responding at 100 mug i.c.v. doses, but showed very little effect at small i.p. doses. Pretreatment with alpha- and beta-adrenergic blockers (i.c.v.) also decreased amphetamine-facilitated responding. The effects of amphetamine or cocaine (i.p.) were not significantly altered by these blockers at the doses used. The depressant effects of the alpha- and beta-adrenergic blockers on self-stimulation behavior appear to be nonspecific with respect to the type of adrenergic receptors.