Acute effect of corticosterone on N-methyl-d-aspartate receptor-mediated Ca ²⁺ elevation in mouse hippocampal slices

We examined the rapid effects of corticosterone (CORT) on N-methyl-d-aspartate (NMDA) receptor-mediated Ca ²⁺ signals in adult mouse hippocampal slices by using Ca ²⁺ imaging technique. Application of NMDA caused a transient elevation of intracellular Ca ²⁺ concentration followed by a decay to a plateau within 150s. The 30min preincubation of CORT induced a significant decrease of the peak amplitude of NMDA-induced Ca ²⁺ elevation in the CA1 region. The rapid effect of CORT was induced at a stress-induced level (0.4-10μM). Because the membrane non-permeable bovine serum albumin-conjugated CORT also induced a similar rapid effect, the rapid effect of CORT might be induced via putative surface CORT receptors. In contrast, CORT induced no significant effects on NMDA-induced Ca ²⁺ elevation in the dentate gyrus. In the CA3 region, CORT effects were not evaluated, because the marked elevation of NMDA-induced Ca ²⁺ signals was not observed there.