Route-dependent effects of the non-NMDA receptor antagonist CNQX on plasma corticosterone levels in mice.

A non-N-methyl-D-aspartate (non-NMDA) receptor antagonist, 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX), administered intracerebroventricularly (0.1-0.5 microg), significantly inhibited the immobilization stress-induced plasma corticosterone levels in a dose-dependent manner. However, CNQX administered intraperitoneally (1-10 mg/kg) showed a dose-dependent increase of basal plasma corticosterone levels in nonstressed mice and an additive increase of plasma corticosterone levels at the dose of 10 mg/kg in 1 h immobilization-stressed mice. The results suggest that the central and peripheral non-NMDA receptors may be differently involved in the regulation of plasma corticosterone levels in non- and immobilization-stressed mice.