Neuronal oxidative damage from activated innate immunity is EP 2 receptor-dependent Thomas J. Montine,* ,  Dejan Milatovic,* Ramesh C. Gupta,à TiborValyi-Nagy,  Jason D. Morrow  , § and Richard M. Breyer  , § Departments of *Pathology,  Pharmacology and §Medicine, Vanderbilt University, Nashville, Tennessee, USA àToxicology Department, Murray State University, Hopkinsville, Kentucky, USA Abstract Increase in prostaglandin (PG) E 2 levels and oxidative dam- age are associated with diseases of brain that involve acti- vation of innate immunity. We tested the hypothesis that cerebral oxidative damage resulting from activation of innate immunity with intracerebroventricular (icv) lipopolysaccharide (LPS) is dependent on PGE 2 -mediated signaling. We meas- ured two quantitative in vivo biomarkers of lipid peroxidation: F 2 -isoprostanes (IsoPs) that derive from arachidonic acid (AA) that is uniformly distributed in all cell types in brain, and F 4 -neuroprostanes (NeuroPs) that derive from docosahexae- noic acid (DHA) that is highly concentrated in neuronal membranes. LPS stimulated delayed elevations in cerebral F 2 -IsoPs and F 4 -NeuroPs that were completely suppressed by indomethacin or ibuprofen pre-treatment. LPS-induced cerebral oxidative damage was abolished by disruption of subtype 2 receptor for PGE 2 (EP 2 ). In contrast, initial oxidative damage from icv kainic acid (KA) was more rapid than with LPS also was completely suppressed by indomethacin or ibuprofen pre-treatment but was independent of EP 2 receptor activation. The protective effect of deleting the EP 2 receptor was not associated with changes in cerebral eicosaniod pro- duction, but was partially related to reduced induction of nitric oxide synthase (NOS) activity. These results suggest the EP 2 receptor as a therapeutic target to limit oxidative damage from activation of innate immunity in cerebrum. Keywords: excitotoxicityinnate immunity, isoprostanes, neu- roprostanes, NSAIDs, prostaglandin E 2 . J. Neurochem. (2002) 83, 463–470. Coincident cerebral oxidative damage and elevated prosta- glandin (PG) E 2 levels are characteristic of several degen- erative and destructive diseases of brain including stroke, epilepsy, Alzheimer’s disease, HIV-associated dementia, and Creutzfeldt–Jakob disease (Griffin et al.1994;PaceandLeaf 1995; Montine et al. 1998, 1999a, 1999b; Paoletti et al. 1998; Thornhill and Smith 1998; Minghetti et al. 2000). PGE 2 potently modulates neurodegeneration and oxidative damage in several model systems; however, some have concluded that PGE 2 is neuroprotective while others have proposed that PGE 2 promotes neuronal damage (Akaike et al. 1994; Cazevielle et al. 1994; Minghetti et al. 1997a, 1997b, 1998; Bezzi et al. 1998; Caggiano and Kraig 1998, 1999; Levi et al. 1998; Paoletti et al. 1998; Thornhill and Smith 1998; Aloisi et al. 1999; Kelley et al. 1999; Sanzgiri et al. 1999; Drachman and Rothstein 2000; Hewett et al. 2000). Most in vivo studies suggest that PGE 2 contributes to oxidativedamageandneurodegeneration,whilemost invitro studiesindicatethatPGE 2 hasneuroprotectiveactivity.There are several possible explanations for these disparate results. Cell culture models typically are limited by use of supra- physiologic concentrations of PGE 2 ,bytheabsenceofsome of the PGE 2 receptor (EP) subtypes, and by disruption of paracrine interactions between neurons and glia. In vivo studies have relied on non-steroidal anti-inflammatory drugs (NSAIDs) to block PGE 2 production and therefore are confounded by suppression of all cyclo-oxygenase (COX) products and some COX-independent actions, including Received May 6, 2002; revised manuscript received July 22, 2002; accepted July 25, 2002. Address correspondence and reprint requests to Thomas J. Montine, Department of Pathology, University of Washington, Box 359791, Harborview Medical Center, 325 9 th Avenue, Seattle, WA 98104, USA. E-mail: tmontine@u.washington.edu Abbreviations used: AA, arachidonic acid; COX, cyclo-oxygenase; DHA, docosahexaenoic acid; GFAP, glial fibrillary acidic protein; icv, intracerebroventricular; IsoPs, isoprostanes; KA, kainic acid; LPS, lipo- polysaccharide; NeuroPs, neuroprostanes; NOS, nitric oxide synthase; NSAIDs, non-steroidal anti-inflammatory drugs; PG, prostaglandin; TX, thromboxane. Journal of Neurochemistry , 2002, 83, 463–470 Ó 2002 International Society for Neurochemistry, Journal of Neurochemistry , 83, 463–470 463