PEPTIDASE INHIBITORS POTENTIATE THE EFFECTS OF NEUROTENSIN AND NEUROMEDIN-N ON SELF-STIMULATION OF THE MEDIAL PREFRONTAL CORTEX

THE purpose of this study was to examine the possible role of endogeno us peptidases in the inhibition of intracranial self-stimulation (ICSS ) produced by injections of neurotensin (NT) and neuromedin N (NN) int o the medial prefrontal cortex (MPC) of the rat. We studied the effect s on ICSS of the MPC of the administration of thiorphan and bestatin, two specific inhibitors of the peptidases that inactivate NT and NN re spectively. Microinjections into MPC of thiorphan (10 mu g) and bestat in (25 mu g) potentiated in inhibition of ICSS produced by the intraco rtical administration of NT (10 nmol) and NN (20 nmol) respectively. T his potentiation affected both the amplitude and the duration of the i nhibition of ICSS produced by the neuropeptides. Our data indicate tha t endogenous peptidases are involved in the inactivation of NT and NN in the prefrontal cortex.