Figure 4.

TRPM2^−/− hippocampi have reduced GluN2B expression and increased GluN2A expression. Western blots detecting glutamate receptor expression in hippocampal protein extracts from 3- to 8-week-old TRPM2^−/− and WT animals. A, B, Densitometry of protein expression of AMPA subunits GluA1 and GluA2 showed no significant difference between TRPM2^−/− and WT (p > 0.05; n = 4 blots with 3 samples of each genotype). C, NMDA subunit GluN1, which binds to GluN2 subunits, also did not have any significant change in protein expression, suggesting that total NMDAR is the same between TRPM2^−/− and WT hippocampi. D–F, However, protein expression of NMDAR GluN2 subunits did change, where basal GluN2A expression was increased by 43.30 ± 2.33% in the TRPM2^−/− (gray bar) compared with WT (black bar; n = 3; D). *p < 0.01. Both basal and active GluN2B is reduced in TRPM2^−/− by 46.21 ± 3.18% and 39.55 ± 1.22%, respectively, compared with WT (n = 3) (E, F). *p < 0.01. G, H, Western blots and densitometry of neuronal cultures from WT and TRPM2^−/− mice show that absence of TRPM2 increased GluN2A expression by 47.30 ± 12.57% (n = 3, *p < 0.05) and decreased GluN2B expression by 43.66 ± 12.44% (n = 3, *p < 0.05) compared with WT primary neuronal cultures. I, J, Primary glial cultures showed no change in GluN2A and GluN2B expression (n = 3, p > 0.05).