CHRONIC COCAINE ADMINISTRATION TO RATS ALTERS THE DISTRIBUTION OF CELL-TYPES RECORDED IN-VITRO WITHIN THE DORSOLATERAL SEPTAL NUCLEUS

We investigated persistent changes in single-neuron activity in the do rsolateral septal nucleus (DLSN) induced by chronic administration of cocaine. Intracellular recording techniques were utilized with an in v itro brain slice preparation to examine the effects of in vivo chronic cocaine administration, for 7 days or 14 days, on the distribution of electrophysiologically characterized DLSN cells. We have previously d istinguished DLSN neurons into three major types (I, II, and III), bas ed upon their action potential configuration and firing pattern. This study demonstrated that type III neurons were overrepresented in brain slices obtained from rats treated chronically with cocaine in vivo fo r 14 days when compared with brain slices obtained from rats treated e ither with cocaine for only 7 days or with saline and never exposed to cocaine. These data provide further evidence that neurons undergo pla stic changes following chronic cocaine administration.