Effects of adrenalin on novelty choices and activity in rats

Rearing, ambulation and occupancy of the novel half of an exploration box were observed in Wistar albino rats following intraperitoneal injections of saline, 0.03 or 0.06 mg/kg adrenalin. All three responses were decreased by the drug in a dose-related manner. Adrenalin did not seem to impair ability to discriminate between novel and familiar stimuli since the percentage of rearing that occurred in the novel half was highest in rats who received the 0.06 mg/kg dose. It was concluded that the suppression of novelty choices (and probably rearing and ambulation) by adrenalin was mainly due to its aversive peripheral properties. Pretreatment with 20 mg/kg oxprenolol HCl largely prevented the effects observed earlier, thereby implicating -adrenoceptors in adrenalin's behavioral action.