Modification by propranolol and related compounds of motor activity and stereotype behaviour induced in the rat by amphetamine

Pretreatment of rats with 4 β-adrenoceptor antagonists, d,1- and d-propanol, oxprenolol and practolol, resulted in a decrease in hypermoyility produced by d,1-amphetamine, 2 mg/kg. This effect occured with similar amounts of all 4 agents over a narrow dose range, 0.4 = 1 mg/kg; higher doses were generally ineffective. Injection of d,1-propranolol and oxprenolol after amphetamine caused an increase in hypermotility, while d-propranolol and practolol did not. Non of these agents had any effect on amphetamine-induced stereotype behaviour in amounts ranging from 0.2 to 10 mg/kg. The results are compatible with the suggestion that all the above drugs may reduced hepermotility by diminishing central noradrenaline release. Increased motor activity induced by d,1-propranolol and oxprenolol may result from a blockade of the inhibitory effects of noradrenaline via β-receptors.