The effects of endotoxin, glucocorticoids and prostaglandin metabolism in the rabbit iris.
Superoxide dismutase activity (SOD) was measured in the irides of control animals (n = 16) and 24 hours after the intravitreal administration of endotoxin (n = 12). Nearly a twofold increase in SOD was noted in the endotoxin-treated animals (p less than 0.001). In order to assess the induction of SOD while protecting against the inflammatory process, topical dexamethasone (dex) was administered t.i.d. for 2 days before and 1 day after endotoxin (n = 6). Dex prevented the conjunctival hyperemia, vascular injection and iritis seen with endotoxin treatment alone and blocked the induction of SOD. A similar medrysone (med) application (n = 4) failed to prevent the visible signs of ocular inflammation yet also blocked the elevation of SOD. Pretreatment with either of the cyclooxygenase inhibitors, indomethacin (n = 4) or aspirin (n = 7), failed to block the induction in SOD (p less than 0.001 and p less than 0.01, respectively). However, the induction of SOD was prevented by the phospholipase A2 inhibitor, quinacrine, and the lipoxygenase inhibitor, nordihydroguaiaretic acid (NDGA). The data indicate that a product of the lipoxygenase pathway may be mediating the induction of SOD seen with endotoxin-induced ocular inflammation.
Recasens
J F
JF
Dept. of Ophthalmology, Medical College of Georgia, Augusta 30912.
Costarides
A P
AP
Green
K
K
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004731:Endotoxins / Q000037:antagonists & inhibitors / Q000633:toxicity*; D004790:Enzyme Induction / Q000187:drug effects; D005938:Glucocorticoids / Q000378:metabolism*; D007500:Iritis / Q000139:chemically induced / Q000517:prevention & control; D011453:Prostaglandins / Q000378:metabolism*; D011817:Rabbits; D013482:Superoxide Dismutase / Q000096:biosynthesis*
D000893:Anti-Inflammatory Agents; D000894:Anti-Inflammatory Agents, Non-Steroidal; D004731:Endotoxins; D005938:Glucocorticoids; D011453:Prostaglandins; C044101:endotoxin, Escherichia coli; D003907:Dexamethasone; D013482:Superoxide Dismutase