The α2-adrenoceptor antagonist atipamezole reduces the development and expression of d-amphetamine-induced behavioural sensitization

The possible effect of atipamezole, a potent and specific α2-adrenoceptor antagonist, on the development and expression of d-amphetamine-induced behavioural sensitization was evaluated in mice. Male (C57Bl/6J) mice were given daily doses of d-amphetamine (2 mg/kg). In addition, groups of mice received injections of atipamezole (0.3 or 1 mg/kg) 20 min before d-amphetamine or vehicle administration. Idazoxan (1 mg/kg) was used in some experiments to extend the results to other α2-adrenoceptor antagonists. Challenge doses of d-amphetamine were administered to the mice on days 7–9 to evaluate the effects of α2-adrenoceptor antagonists on the d-amphetamine sensitization, evidenced by increased locomotor activation.