Abstract
Pretreatment with the selective noradrenergic uptake inhibitors nisoxetine and desipramine antagonized the locomotor stimulant effect of d-amphetamine without reducing the drug's stereotypy-inducing action. A similar antagonism was observed with imipramine but not with fluoxetine, a selective serotonin uptake inhibitor and structural analog of nisoxetine. The order of potency of antagonism was desipramine > nisoxetine > imipramine. Nisoxetine also selectively reduced the locomotor activity induced by maximally effective doses of cocaine, d-N-ethylamphetamine, and methylphenidate, but not that induced by morphine. Biochemically, nisoxetine blocked the selective reduction in cerebral cortical endogenous and 3H-norepinephrine produced by amphetamine without itself significantly altering either measure. These data support the involvement of norepinephrine in the locomotor stimulant action of indirectly acting sympathomimetic amines.