Induction of cyclooxygenase-2 in the rat brain after a mild episode of focal ischemia without tissue inflammation or neural cell damage.

Cyclooxygenase-2, a key enzyme in prostanoid synthesis, is induced by inflammatory stimuli and it is associated with cell death after cerebral ischemia. Here we evaluated whether cyclooxygenase-2 was induced after a short (10-min) episode of focal ischemia, mild enough not to cause inflammation or cell death. One-hour ischemia leading to brain infarct was studied for comparative purposes. Induction of cyclooxygenase-2 mRNA and protein was detected after both 10-min and 1-h ischemia. However, signs of edema were only apparent after 1-h, but not 10-min ischemia, and only rats subjected to 1-h ischemia had developed brain infarct at 4 days. Therefore, cyclooxygenase-2, not linked with neural cell death or inflammation, is induced after focal ischemia.