Abstract
Many reports have shown the presence of D-serine in the forebrain and the co-localization of D-serine with N-methyl-D-aspartate (NMDA) receptor. D-Serine is thought to activate the NMDA receptor, which has important role in the long-term potentiation (LTP) and learning. To evaluate the role of D- serine, spatial learning using the Morris water maze and LTP in the CA1 area of hippocampal slice preparation were compared between the wild-type mice and mutant mice lacking D-amino-acid oxidase, an enzyme which metabolizes D-serine. The platform search times in the water maze were not different in the initial phase of training. However, in later phase of training, the platform search time was significantly shorter in the mutant mice than in the wild-type mice. Furthermore, platform quadrant search time was significantly longer in the mutant mice than in the wild-type mice. Tetanus-induced LTPs, measured as the increase of the field EPSP slope after tetanus stimulation, were observed in the CA1 area of both type mice. However, tetanus-induced LTPs were significantly larger in the mutant mice than in the wild-type mice. We suggest that D-serine rich in the mutant mouse brain increases hippocampal LTP and then facilitates spatial learning. [Jpn J Physiol 55 Suppl:S183 (2005)]
