The interaction of central oxytocin and cholecystokinin regulates grooming behavior in the rat.

Oxytocin (OXY) and cholecystokinin (CCK) coexisting in neurons of the hypothalamic paraventricular nucleus (PVN) induce grooming behavior when microinjected into the ventral tegmentum. The present study sought to investigate two other putative terminal fields of this peptide-peptide coexistence, the lateral hypothalamus (LH) and the medial preoptic area (MPOA), and to determine the functional interaction between OXY and CCK. Microinjection of OXY and CCK alone or in combination into the LH but not into the MPOA induced grooming. Both peptides seem to be equally critical for the induction of grooming; they may interact on a common substrate by suppressing each other's effect.