Mesolimbic and mesocortical dopaminergic neurons are necessary for normal exploratory behavior in rats

After ablation of mesolimbic and mesocortical dopaminergic neurons produced by 6-hydroxydopamine (6-OHDA) injections in the anterolateral hypothalamus, rats investigate a novel object less. Systemic administration of the dopamine (DA) agonist apomorphine increases investigatory movements in these DA-denervated rats when the object is novel, but not when the object is familiar. Pimozide pretreatment prevents the increased investigation produced by apomorphine in DA-denervated rats. These findings suggest that mesolimbic and mesocortical DA neurons are necessary for normal exploratory behavior in the rat.