Changes of NR2B and c-fos mRNA Expressionin Rat Hippocampal CA1 Neuronal ChangeFollowing Hypoxia and Reoxygenation / 대한해부학회지

ABSTRACT

Vulnerability of hippocampal CA1 neurons after brain hypoxia is coupled with high concentration of NMDA recep-tor subunits especially NR2 subunits. These subunits can be regarded as modulators, since NMDA receptors display different properties depending on which of the NR2 subunits assembles with NR1. Stimulation of NMDA receptors opens a receptor-gated Ca2+ channel; and the Ca2+ influx is believed to play a critical role in c-fos expression that require alterations in gene expression. We examined the effect of the NMDA subunits (NR1, NR2A, NR2B) mRNA level on the c-fos activation and CA1 neuronal change by in situ hybridization and TUNEL method following hypoxia and reoxygenation. Present studies show that high expression and variability of NR2B mRNA in CA1 region, compared with those of NR1 and NR2A, at our experimental time window suggest that NR2B is main functional subunit in the determining of properties of NMDA receptor in hypoxic hippocampal CA1 cells. From 0 hour to 6 hours, TUNEL positive reaction and c-fos mRNA expression were steadily increased. Thereafter, TUNEL positive reaction was decreased compared with that of 6 hours and c-fos mRNA expression was decreased and then steadily re-increased from 3 days to 6 days. Therefore, high expression of NR2B and subsequent Ca2+ influx may play important roles in the hippocampal CA1 neuronal apoptosis and c-fos expression. In addition, c-fos expression may play different roles in neuronal apoptosis in a time-dependent manner.