Role of NMDA NR1 subunit in pathophysiology of schizophrenia

Our work is focused on the role of NR1 subunit of N-methyl-D-aspartate receptor in pathophysiology of schizophrenia. In animal model using separately or in combination, antisense oligodeoxynucleotide (aODN) for NR1, NR2A and NR2B subunit of NMDAR, we affected expression of these proteins in rat hippocampus. We assessed prepulse inhibition of acoustic startle reaction (PPI) in rats and protein expression of NMDAR subunits and expression of PSD proteins. There were significant differences in expression of PSD-95 and NR1 between groups. Application of aODN (NR2A, NR2B) was associated with a significant decrease of PSD-95. PPI and expression of NR2A, NR2B and PSD-93 were not changed after aODN application.The next part of the work concentrates on a human post mortem study. To assess actual changes in the expression of the NR1 subunit and its isoforms, we measured absolute differences in the levels of mRNA/protein for panNR1, as well as the individual mRNA/protein isoforms in the post mortem left/right hippocampus of patients with schizophrenia in comparison with non-psychiatric subjects. There were no significant differences in the panNR1 subunit mRNA expression, but the absolute left/right differences were much more pronounced in the patients with schizophrenia. The expression of splice variants in the..

Expression of the hippocampal NMDA receptor GluN1 subunit and its splicing isoforms in schizophrenia: postmortem study. Neurochem. Res. 35, 994– 1002. Conflict of Interest Statement: The authors declare that the research was conducted in the absence of an

Abstract There is accumulating evidence that disturbances in N-methyl-D-aspartate receptor (NMDA-R) functioning are associated with the pathogenesis of schizophrenia. To assess actual changes in the expression of the GluN1 subunit and its isoforms, we measured absolute differences in the levels of mRNA/protein for panGluN1 (eight isoforms altogether) as well as the mRNA individual isoforms in the postmortem left/right hippocampus of patients with schizophrenia in comparison with non-psychiatric subjects. There were no significant differences in the panGluN1 subunit mRNA expression, but the absolute left/right differences were much more pronounced in the patients with schizophrenia. Protein levels of the GluN1 subunit in the left hippocampus in male schizophrenic patients were lower than controls. The expression of the NR1-4b isoform was attenuated in the left, whereas the NR1-2b was reduced in the right hippocampus of schizophrenic patients. Isoforms associated with the efficiency of NMDA-induced gene expression and with phosphorylation occurred more commonly in schizophrenic hippocampi. In summary, our study suggests that NMDA-R hypofunction in schizophrenia might be selectively dependent on the dysregulation of GluN1 subunit expression, which exhibits a somewhat different expression in the left/right hippocampus of psychotic patients

N-Methyl-d-Aspartate Receptor – Nitric Oxide Synthase Pathway in the Cortex of Nogo-A-Deficient Rats in Relation to Brain Laterality and Schizophrenia

It has been suggested that Nogo-A, a myelin-associated protein, could play a role in the pathogenesis of schizophrenia and that Nogo-A-deficient rodents could serve as an animal model for schizophrenic symptoms. Since changes in brain laterality are typical of schizophrenia, we investigated whether Nogo-A-deficient rats showed any signs of disturbed asymmetry in cortical N-methyl-D-aspartate (NMDA) receptor–nitric oxide synthase (NOS) pathway, which is reported as dysfunctional in schizophrenia. In particular, we measured separately in the right and left hemisphere of young and old Nogo-A-deficient male rats the expression of NMDA receptor subunits (NR1, NR2A and NR2B in the frontal cortex) and activities of NOS isoforms (neuronal (nNOS), endothelial (eNOS) and inducible (iNOS) in the parietal cortex). In young controls, we observed right/left asymmetry of iNOS activity and three positive correlations (between NR1 in the left and NR2B laterality, between NR2B in the right and left sides, and between NR1 in the right side and nNOS laterality). In old controls, we found bilateral decreases in NR1, an increase in NR2B in the right side and two changes in correlations in the NR1–nNOS pathway. In young Nogo-A-deficient rats, we observed an increase in iNOS activity in the left hemisphere and two changes in correlations in NR1–nNOS and NR2A–eNOS, compared to young controls. Finally, we revealed in old Nogo-A-deficient animals, bilateral decreases in NR1 and one change in correlation between eNOS–iNOS, compared to old controls. Although some findings from schizophrenic brains did not manifest in Nogo-A-deficient rats (e.g., no alterations in NR2B), others did (e.g., alterations demonstrating accelerated ageing in young but not old animals, those occurring exclusively in the right hemisphere in young and old animals and those suggesting abnormal frontoparietal cortical interactions in young animals)