Vasopressin, a peptide that appears to enhance the consolidation process of memory was studied for its ability to stimulate the accumulation of cyclic AMP in slices of the mouse hippocampus. While vasopressin alone exhibited no effects in this system, it substantially potentiated the effects of norepinephrine. Such actions are discussed in reference to an endogenous brain vasopressin system, and they suggest a possible neuromodulator role for vasopressin.