Intracranial self-stimulation from the sulcal prefrontal cortex in the rat: the effect of 6-hydroxydopamine or kainic acid lesions at the site of stimulation.

An electrode cannula system was used to elicit intracranial self-stimulation (ICSS) from the sulcal prefrontal cortex in rats to test the behavioral effects of local infusions of 6-hydroxydopamine (6-OHDA) or kainic acid (KA) into the brain area surrounding the electrode tip. In experiment I sulcal ICSS animals received injections of 6-OHDA with or without desipramine (DMI) pretreatment to block 6-OHDA uptake into noradrenergic (NA) terminals. Those animals that received DMI pretreatment were subsequently shown to have sustained sulcal cortical dopaminergic (DA) denervation while sulcal molecular layer NA systems were spared as revealed with glyoxylic acid-induced catecholamine histofluorescence. Those animals not receiving DMI pretreatment sustained near-complete denervation of both NA and DA sulcal cortical systems. Neither treatment had a lasting effect on sulcal ICSS suggesting that sulcal ICSS is not dependent on the presynaptic release or DA of NA into that brain area. In experiment II KA injections that lesioned neurons in sulcal cortical layers V and VI resulted in the abolition of sulcal ICSS for the duration of a 21 day postlesion trial period. These results suggest that activation of a descending corticofugal system originating in the sulcal cortex is responsible for the mediation of sulcal prefrontal cortical ICSS. This system was mapped by the selective silver impregnation of degenerating neural elements resulting from effective lesions.