Genetic Inactivation of the NMDA Receptor NR2A Subunit has Anxiolytic- and Antidepressant-Like Effects in Mice

Abstract

There is growing evidence implicating the glutamate system in the pathophysiology and treatment of mood and anxiety disorders. Glutamatergic neurotransmission is mediated by several receptor subfamilies including multiple NMDA receptor subunits (NR2A-D). However, little is currently understood about the specific roles of NMDA subunits in the mediation of emotional behavior due to a lack of subunit-specific ligands. In the present study, we employed a mouse gene-targeting approach to examine the role of the NR2A subunit in the mediation of anxiety-and depressive-related behaviors. Results showed that NR2A knockout (KO) mice exhibit decreased anxiety-like behavior relative to wild-type littermates (WT) across multiple tests (elevated plus maze, light-dark exploration test, novel open field). NR2A KO mice showed antidepressant-like profiles in the forced swim test and tail suspension test, as compared to WT controls. Locomotor activity in the nonaversive environments of the home cage or a familiar open field were normal in the NR2A KO mice, as were gross neurological and sensory functions, including prepulse inhibition of startle. Taken together, these data demonstrate a selective and robust reduction in anxiety-and depression-related behavior in NMDA receptor NR2A subunit KO mice. Present results support a role for the NR2A subunit in the modulation of emotional behaviors in rodents and provide insight into the role of glutamate in the pathophysiology and treatment of mood and anxiety disorders.

Mice lacking the AMPA GluR1 receptor exhibit striatal hyperdopaminergia and ‘schizophrenia-related’ behaviors

“…To control for possible phenotypic abnormalities in physical health, and simple sensory and neurological functions, KO were evaluated on a functional observation battery 39 (Supplementary Table 1).…”

“…Single and repeated OF exposure Mice were placed in a corner of a square (39 Â 39 Â 35 cm) OF 39 with opaque white Plexiglas walls and floor (B95 lx) and allowed to freely explore for 3 h. A separate cohort was tested in the same manner for 30 min once daily for 5 consecutive days. Total distance traveled was quantified using the Ethovision videotracking system (Noldus Information Technology, Leesburg, VA, USA).…”

“…39 Activity was then measured for 24 h using the photocell-based Opto M3 activity monitor (Columbus Instruments, Columbus, OH, USA).…”

Ontogeny of fear-, anxiety- and depression-related behavior across adolescence in C57BL/6J mice

“…The novel open field test was conducted as previously described [7]. The apparatus was a 40 × 40 × 35 cm square arena (50 lux) constructed of white Plexiglas.…”

“…The forced swim test was conducted as previously described [7,40]. The apparatus was a transparent Plexiglas cylinder 25 cm high, 20 cm diameter) filled halfway with water (24 ± 1°C ) such that the mouse could not touch the bottom with its tail.…”