Abstract
Recent studies have shown that D-serine is abundant in the brain area enriched in N-methyl-D-aspartate (NMDA) receptors and that exogenously applied D-serine potentiates NMDA receptor-mediated neurotransmission. Therefore, D-serine is thought to modulate endogenously NMDA receptor functions. Since NMDA receptors play an important role in the learning, we thought that D-serine could have some effect on the behavior based on the memory and learning. The normal mice and mutant mice lacking D-amino-acid oxidase (DAO), an enzyme which metabolizes D-serine, were used for the behavior study. In the mutant mice, the brain concentration of D-serine thought to be higher than normal mice. We examined the difference in learning ability between the mutant mice and normal mice to characterize the learning behavior of the mutant mice. The learning ability was examined using Morris water maze: the swimming time for the mice to reach the hidden platform was recorded every day for a week. We observed that the swim time was longer in the mutant mice than in the normal mice, and that the decline of the swim time by training in the mutant mice was slower than that in the normal mice. These results suggest that high concentration of D-serine in brain of the mutant mice lacking DAO might have negative effect on the learning behavior. [Jpn J Physiol 54 Suppl:S189 (2004)]
