title: Long-term elevation of cyclooxygenase-2, but not lipoxygenase, in regions synaptically distant from spreading depression.
abstract: Eicosanoids, produced from arachidonic acid by cyclooxygenases (COXs) and lipoxygenases (LIPOXs), are involved in numerous brain processes. To explore if brief and noninjurious stimuli chronically alter expression of these enzymes, we examined the induction of COX-2 and LIPOX expression following unilateral neocortical spreading depression (SD). Expression was examined over time and in regions not experiencing SD (hippocampus) but synaptically connected to the site of stimulation (cortex). One hundred six male Wistar rats had SD induced via microinjection of 0.5 M KCl (0.5 M NaCl for sham) into left parietal cortex every 9 minutes for 1 or 3 hours. One hour before SD some animals received dexamethasone (Dex), mepacrine (Mep), indomethacin (Indo), nordihydroguaiaretic acid (Ndga), phenylephrine (Pe), sodium nitroprusside (Snp) with Pe, or N omega-nitro-L-arginine methyl ester (Lnam). Animals survived for 0, 3, or 6 hours, or 1, 2, 3, 7, 14, 21, or 28 days. Brains were processed immunohistochemically for COX-2 and LIPOX, and the optical density (OD) of the left and right cortex, dentate gyrus (DG), CA3, and CA1 immunoreactivity (IR) were measured. Induction was expressed as the log of left divided by right side OD for each region. COX-2 IR in the left cortex was elevated rapidly and was sustained for 21 days following SD. COX-2 IR was also elevated in the ipsilateral hippocampus not experiencing SD, with the rank order of induction as follows: DG > CA3 > CA1. Dex, Snp, and/or Pe significantly reduced the induction of COX-2. No changes in LIPOX IR were observed. These results show that long-term changes in COX-2 expression are induced by SD and these changes decrease with synaptic distance. Benign stimuli increase COX-2 expression and thus may influence brain function for extended periods and at distant locations.
authors.affiliation: Committee on Neurobiology, University of Chicago, Illinois 60637, USA.
authors.forename: A O
authors.initials: AO
authors.lastname: Caggiano
authors.forename: C D
authors.initials: CD
authors.lastname: Breder
authors.forename: R P
authors.initials: RP
authors.lastname: Kraig
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D000918:Antibody Specificity; D002540:Cerebral Cortex / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D013181:Cortical Spreading Depression / Q000502:physiology*; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005938:Glucocorticoids / Q000494:pharmacology; D006624:Hippocampus / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D007150:Immunohistochemistry; D007213:Indomethacin / Q000494:pharmacology; D007527:Isoenzymes / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D008084:Lipoxygenase / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008297:Male; D009637:Masoprocol / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D011796:Quinacrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000201:enzymology*; D013997:Time Factors; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D005938:Glucocorticoids; D007527:Isoenzymes; D016859:Lipoxygenase Inhibitors; D014665:Vasodilator Agents; D009599:Nitroprusside; D010656:Phenylephrine; D009637:Masoprocol; D003907:Dexamethasone; D008084:Lipoxygenase; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D011796:Quinacrine; D007213:Indomethacin