Distribution and expression of the subunits of N-methyl- d-aspartate (NMDA) receptors; NR1, NR2A and NR2B in hypoxic newborn piglet brains

Abstract

The purpose of this study was to identify the distribution and the expression of the NR1, NR2A and NR2B subunits of the NMDA receptor after cerebral hypoxia. Ten piglets were divided into control and hypoxic groups ( n=5, each). The control piglets were ventilated with normoxia for 1 h, and the hypoxic piglets were ventilated with hypoxia until p aO 2 was below 20 mmHg. Tissue samples from the nine different regions of newborn piglet brain were obtained, and the protein amount of the NR1, NR2A, and NR2B subunits measured by immunoblot using the antibody to the NR1, NR2A, and NR2B subunits. The NR1, N2A, and NR2B subunits were distributed very differently; hippocampus and cortical area are more prominent than white matter and cerebellum. But the expression of the NR1, NR2A and NR2B subunits were not significantly different between the control and the hypoxic group, 1 h after hypoxic exposure, indicating no changes in the protein amount of NMDA receptor subunits. These results show a significantly higher amount of the NR1, NR2A and NR2B subunits in the hippocampus and the cerebral cortex of newborn brains, indicating that these structures could be highly vulnerable to excitotoxicity in the newborn brain.