BN 80933 Inhibits F2-isoprostane elevation in focal cerebral ischaemia and hypoxic neuronal cultures

Abstract

Formation of the lipid peroxidation product 8-epi-prostaglandin2alpha (8-epi-PGF2alpha) a bioactive marker of oxidative stress, was quantified in in vitro and in vivo models of neuronal death. In culture media of primary rat cortical neurones exposed to hypoxia followed by reoxygenation, a 3.7-fold increase of 8-epi-PGF2alpha concentration was observed in comparison to control cells. In rats submitted to 2h middle cerebral artery occlusion followed by a 22h reperfusion period, a 27-fold increase of 8-epi-PGF2alpha was observed in the ischaemic hemisphere compared with the corresponding hemisphere of sham-operated rats. Treatment with the neuroprotective agent BN 80933 significantly reduced both 8-epi-PGF2alpha elevations in vitro and in vivo. These data suggest that 8-epi-PGF2alpha elevations might reflect the damaging free radical overproduction and subsequent lipid peroxidation during neuronal injury induced by hypoxia and ischaemia. Inhibition of 8-epi-PGF2alpha elevations participates to the neuroprotective effects of BN 80933.

LC/MS/MS method for analysis of E2 series prostaglandins and isoprostanes

“…Upon ischemia, free PGE 2 and PGD 2 were signifi cantly increased with a more profound increase in PGD 2 mass ( Table 2 ), which is consistent with previous studies ( 29,37,38,46 ). Total (free plus esterifi ed) isoPGs were significantly increased ‫ف‬ 2-fold, which is consistent with increased oxidative stress upon ischemia ( 47,48 ) and consistent with the increase in free isoPGE 2 /D 2 levels in decapitated rat brains ( 38 ). The found values for brain isoPG are in the range of the previously reported values for rat liver ( 15 ).…”

Neuroprotection by tamoxifen in focal cerebral ischemia is not mediated by an agonist action at estrogen receptors but is associated with antioxidant activity

“…However, the equivalent values for all the control levels implies that the increases specific to ipsilateral brain tissue is the true increase due to ischemia and reduction by tamoxifen to the control levels means that tamoxifen completely inhibits the ischemia-induced increases. Marin et al (2000) reported relatively much lower levels in contralateral brain tissue from rMCAo animals. In these studies the removed hemispheres were frozen in liquid N 2 and the isoprostane levels of the entire hemispheres measured with no dissection of the different regions.…”

“…To see whether this protection correlated with antioxidant activity under the same conditions we tested the antioxidant effects of 5 mg/kg tamoxifen given 3 hours after initiation of ischemia as measured by effects on isoprostane appearance. We chose to study effects on isoprostane levels as these compounds are emerging as stable markers of lipid peroxidation and hence free radical damage in cerebral ischemia (Marin et al, 2000), For IsoPs in the striatum, there was a significant effect of treatment (p = 0.015) and a significant interaction effect (p = 0.025), reflecting a difference in the response of ischemic versus nonischemic tissue to the effect of tamoxifen. The IsoPs levels in the ischemic vehicle-treated striatum were significantly higher than all other striatal tissue (all p values < 0.038).…”

“…Lipid peroxidation is initiated by a free radical-induced abstraction of a hydrogen from the polyunsaturated fatty acyl side chains of membrane lipids (phospholipids, glycolipids, glycerides and sterols), especially by hydroxyl radical and peroxynitrite radicals (Mattson, 1998). IsoPs are prostanoids produced independently of cyclooxygenase by free radicalcatalysed peroxidation of arachidonic acid-containing lipids (Marin et al, 2000). Quantification of IsoPs has therefore been proposed as an accurate marker of oxidative stress in experimental models of free radical-induced injury and human diseases being deemed more reliable and specific than the more commonly measured thiobarbituric acid reactive substances (TBARS) and malondialdehyde (MDA) (Cherubini et al, 2005).…”

“…In this study, we tested whether the neuroprotective effect of tamoxifen depends on its action at estrogen receptors by seeing if neuroprotection by tamoxifen was affected by estrogen blockade by ICI 182,780, a high affinity estrogen receptor antagonist (IC 50 = 0.29 nM) devoid of any partial agonism both in vitro and in vivo (Wakeling et al, 1991;Howell et al, 2000). We also tested whether tamoxifen shows antioxidant activity in a reversible middle cerebral artery occlusion (MCAo) model under the same conditions where it shows protection by testing whether an increase in F 2 -isoprostanes (IsoPs) and F 4 -neuroprostanes (NeuroPs), as biomarkers of oxidative damage, were inhibited (Marin et al, 2000;Milatovic et al, 2005;Montine et al, 2002). IsoPs are considered accurate markers of general free radical damage to brain tissue, while NeuroPs uniquely reflect free radical damage to neuronal membranes in vivo (Montine et al, 2004).…”