The second messengers cAMP and cGMP are important mediators of signal transduction and hence a wide range of cellular processes including vasodilation and synaptic plasticity. Type 2 cyclic nucleotide phosphodiesterases (PDE2) isoforms inactivate cAMP and cGMP by hydrolyzing the phosphodiester bond. BAY 60-7550 is a potent PDE2 inhibitor with IC50 values of 2.0 nM (bovine) and 4.7 nM (human). It is 50-fold more selective for PDE2 compared to PDE1 and greater than 100-fold selective compared to PDE5 PDE3B, PDE4B, PDE7B, PDE8A, PDE9A, PDE10A, and PDE11A. At 3 mg/kg BAY 60-7550 antagonizes oxidative stress-induced anxiety-like behavioral effects in mice by increasing cGMP signaling. At 1 mg/kg BAY 60-7550 improves the performance of rats in an object location task, enhancing cAMP/cGMP-mediated object and spatial memory consolidation.