D-cycloserine, a modulator of the N-methyl-D-aspartate receptor, improves spatial learning in rats treated with muscarinic antagonist.

The results of the present study indicate that D-cycloserine, a partial agonist at the glycine binding site, which is a positive modulation site of the N-methyl-D-aspartate receptor, could improve dose dependently the acquisition of a water maze task in rats treated with scopolamine, a muscarinic antagonist. The low to moderate doses of D-cycloserine which improved learning did not affect swimming speed in scopolamine-treated rats. The higher dose did not improve learning, but it increased swimming speed in scopolamine-treated rats. These results show a dissociation between impaired acquisition and abnormal behavioral activity in scopolamine-treated rats in the water maze task. Furthermore, the present results suggest that D-cycloserine can act as a cognitive enhancer at the appropriate doses.