The protective effect of M40401, a superoxide dismutase mimetic, on post-ischemic brain damage in Mongolian gerbils

Abstract

Background: Overproduction of free radical species has been shown to occur in brain tissues after ischemia-reperfusion injury. However, most of free radical scavengers known to antagonize oxidative damage (e.g. superoxide dismutase, catalase), are unable to protect against ischemia-reperfusion brain injury when given in vivo, an effect mainly due to their difficulty to gain access to brain tissues. Here we studied the effect of a low molecular weight superoxide dismutase mimetic (M40401) in brain damage subsequent to ischemia-reperfusion injury in Mongolian gerbils.

Results: In animals undergoing ischemia-reperfusion injury, neuropathological and ultrastructural changes were monitored for 1-7 days either in the presence or in the absence of M40401 after bilateral common carotid artery occlusion (BCCO). Administration of M40401 (1-40 mg/kg, given i.p. 1 h after BCCO) protected against post-ischemic, ultrastructural and neuropathological changes occurring within the hippocampal CA1 area. The protective effect of M40401 was associated with a significant reduction of the levels of malondialdehyde (MDA; a marker of lipid peroxidation) in ischemic brain tissues after ischemia-reperfusion.

Conclusion: Taken together, these results demonstrate that M40401 provides protective effects when given early after the induction of ischemia-reperfusion of brain tissues and suggest the possible use of such compounds in the treatment of neurological dysfunction subsequent to cerebral flow disturbances.

Figure 1

Temporary (5 min) BCCO in Mongolian gerbils leads to damage in the hippocampal CA1 area, compared to sham-operated animals (A), characterized by neurons showing eccentric pycnotic nuclei, intracellular edema and vacuolar degeneration (B). M40401 (40 mg/Kg) given i.p. 1 h after BCCO protected against ischemia-reperfusion hippocampal early lesion (C)

Figure 2

(A-C): ischemia + 1 day recovery: prominent ultrastructural damages of CA1 area of the hippocampus in the site of carotid artery occlusion. In particular, are displayed vacuolated neurons with irregular nuclei and margination of the heterochromatin (pre-apoptotic neurons). Large electron light vacuoles occupy the cytoplasm and the mitochondria are dense and disorganized. In many cells, vacuoles occupy the entire cytoplasm, cell shape is not maintained and the chromatin is dispersed into the cytoplasm (see A). (magnification × 3800). (D) M40401 (40 mg/kg) protected against damage. Indeed, the micrographs show the presence, in the hypothalamic CA1 area of normal neurons with large nuclei with euchromatin and prominent nucleoli. In addition, developed mitochondria, rough endoplasmic reticulum and normal cytoskeleton components are distinguished. In the extracellular space are found preserved myelinic fibers and blood vessels. (magnification × 3800)

Figure 3

Panel A. Representative histological examination of brain hippocampus of Mongolian gerbil's showing significant neuronal loss within CA1 area, compared to sham operated animals, when evaluated 7 days after induction of BCCO. Panel B shows quantitative analysis for CA1 hippocampal neurons detected in sham-operated and BCCO-operated animals either untreated or treated with M40401. In particular, M40401 (40 mg/Kg given i.p. 1 h after BCCO; n = 10) showed protective effect against ischemia-reperfusion-induced reduction of neuronal cell number detected within CA1 hippocampal area.

Figure 4

Time-dependent elevation of malondialdehyde levels (MDA, nmol/g tissue) within the hippocampus of Mongolian gerbils (A). The increase of MDA found 1 day after BCCO was attenuated dose-dependentently by M40401 (1–40 mg/kg; n = 10 for each dose; B). * P < 0.05 ischemic vs M40401-treated gerbils.