Figure 9.

Central inhibition of COX-1 (but not COX-2) activity reduces LPS-induced HPA axis secretory responses. Mean ± SEM plasma levels of ACTH (top) and corticosterone (middle) and of brain tissue (hypothalamic) PGE₂ levels (bottom) in rats pretreated centrally (left column) or systemically (right column) with the selective COX-1 inhibitor SC-560 (SC; 50 μg in 5 μl, i.c.v., or 10 mg/kg, i.v.), the selective COX-2 inhibitor NS-398 (NS; 25 μg in 5 μl, i.c.v., or 5 mg/kg, i.v.), or vehicle (Veh) before intravenous injection of LPS (2 μg/kg) or saline. Central, but not systemic, COX-1 blockade, but not COX-2 blockade, significantly attenuated ACTH and corticosterone secretory responses, as well as tissue (hypothalamic) PGE₂ concentrations, at this time point. *p < 0.05 versus saline-injected animals. n = 5 per group. ^†p < 0.05 versus vehicle-pretreated groups challenged with LPS.