S181. ANALYSIS OF THE AMELIORATING EFFECT OF D-SERINE ON GLUN2D DEFICIENT MICE

BACKGROUND: The glutamate hypothesis of schizophrenia postulates NMDA receptor (NMDAR) hypofunction as a major pathophysiological mechanism based on clinical observations and preclinical evidence. Mice with globally reduced NMDAR expression display hyperlocomotion, sensorimotor gating deficits, cognitive deficits and social withdrawal. NMDARs are tetramers composed of 2 obligatory GluN1 (NR1) and 2 variable GluN2A-D (NR2A-D) subunits. GluN2A and GluN2B are the main cortical NMDAR subunits, but genetic models provided evidence that psychosis-like effects of NMDAR antagonists are mediated by GluN2C/GluN2D subunits. Previous data suggest a role also of the GluN2D subunit in schizophrenia-associated abnormalities [1]. METHODS: We aimed to assess a comprehensive behavioural phenotyping of GluN2D deficient mice, including locomotion, affective behaviours and general welfare, but drew special focus on cognitive functions, including spatial learning, short-term and long-term memory, as well as puzzle solving. We further investigated the effect of D-Serine on the GluN2D KO mice. D-Serine is a NMDAR modulator and acts as an agonist at the glycine site. Previous work in clinical trials suggests significant therapeutic effects of D-serine on negative and positive symptoms, cognitive deficits and motor symptoms. We used the chronic application of D-Serin by supplementing it into the drinking water of the subjects. RESULTS: Preliminary data indicate no effect on locomotor alterations of the GluN2D mice, however a potential improvement in short-term memory and wellbeing-associated parameters. They indicate a role of the GluN2D subunit and a beneficial effect of D-serine on schizophrenia-induced parameters, including physiological, welfare-associated burrowing and cognitive performance in the short term task of the puzzle box test. DISCUSSION: Our preliminary data indicate a role of the GluN2D subunit in the emergence of cognitive deficits associated with schizophrenia and a potential therapeutic effect of D-serine in alleviating these deficits. Further investigations are planned to further validate these findings. REFERENCE: 1. Inta et. al, Neurosci Biobehav Rev, 34(3): 285–94, 2010.