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J. Neurochem. (2010) 113, 1343–1355. The involvement of plasma membrane glutamate transporters (EAATs – excitatory aminoacid transporters) in the pathophysiology of ischemia has been widely studied, but little is known about the role of vesicular glutamate transporters (VGLUTs) in the ischemic process. We analyzed the expression of VGLUT1–3 in the cortex and caudate-putamen of rats subjected to transient middle cerebral artery occlusion. Western blot and immunohistochemistry revealed an increase of VGLUT1 signal in cortex and caudate-putamen until 3 days of reperfusion followed by a reduction 7 days after the ischemic insult. By contrast, VGLUT2 and 3 were drastically reduced. Confocal microscopy revealed an increase in VGLUT2 and 3 immunolabelling in the reactive astrocytes of the ischemic corpus callosum and cortex. Changes in VGLUTs and EAATs expression were differently correlated to neurological deficits. Interestingly, changes in VGLUT1 and EAAT2 expression showed a significant positive correlation in caudate-putamen. Taken together, these results suggest a contribution of VGLUTs to glutamate release in these structures, which could promote neuroblast migration and neurogenesis during ischemic recovery, and a possible interplay with EAATs in the regulation of glutamate levels, at least in the first stages of ischemic recovery. [ABSTRACT FROM AUTHOR]

As phytoestrogens are postulated as being neuroprotectants, we assessed the hypothesis that dietary isoflavone-type phytoestrogens are neuroprotective against ischemic stroke. Transient focal cerebral ischemia (90 min) was induced by middle cerebral artery occlusion (MCAO) following the intraluminal thread technique, both in rats fed with soy-based diet and in rats fed with isoflavone-free diet. Cerebro-cortical laser-Doppler flow (cortical perfusion, CP), arterial blood pressure, core temperature, PaO2, PaCO2, pH and glycemia were measured before, during and after MCAO. Neurological examination and infarct volume measurements were carried out 3 days after the ischemic insult. Dietary isoflavones (both glycosides and aglycones) were measured by high-performance liquide chromatography. Neither pre-ischemic, intra-ischemic nor post-ischemic CP values were significantly different between the soy-based diet and the isoflavone-free diet groups. Animals fed with the soy-based diet showed an infarct volume of 122 ± 20.2 mm3 (19 ± 3.3% of the whole ipsilateral hemisphere volume). In animals fed with the isoflavone-free diet the mean infarct volume was significantly higher, 191 ± 26.7 mm3 (28 ± 4.1%, P < 0.05). Neurological examination revealed significantly higher impairment in the isoflavone-free diet group compared with the soy-based diet group (3.3 ± 0.5 vs. 1.9 ± 0.5, P < 0.05). These results demonstrate that dietary isoflavones improve stroke outcome after transient focal cerebral ischemia in such a way that a higher dietary isoflavone content results in a lower infarct volume and a better neurological status. [ABSTRACT FROM AUTHOR]

Because neuroprotection in stroke should be revisited in the era of recanalisation, the present study analysed the potential neuroprotective effect of the selective oestrogen receptor modulator, bazedoxifene acetate (BZA), in an animal model of diabetic ischaemic stroke that mimics thrombectomy combined with adjuvant administration of a putative neuroprotectant. Four weeks after induction of diabetes (40 mg kg‐1 streptozotocin, i.p.), male Wistar rats were subjected to transient middle cerebral artery occlusion (intraluminal thread technique, 60 minutes) and assigned to one of three groups treated with either: vehicle, BZA (3 mg kg‐1 day‐1, i.p.) or 17β‐oestradiol (E2) (100 μg kg‐1 day‐1, i.p.). At 24 hours post‐ischaemia‐reperfusion, brain damage (neurofunctional score, infarct size and apoptosis), expression of oestrogen receptors (ER)α, ERβ and G protein‐coupled oestrogen receptor), and activity of the mitogen‐activated protein kinase/extracellular signal‐regulated kinase (MAPK/ERK)1/2 and phosphoinositide 3‐kinase/Akt pathways were analysed. At 24 hours after the ischaemic insult, both BZA‐ and E2‐treated animals showed lower brain damage in terms of improved neurofunctional condition, decreased infarct size and decreased apoptotic cell death. Ischaemia‐reperfusion induced a significant decrease in ERα and ERβ expression without affecting that of G protein‐coupled oestrogen receptor, whereas BZA and E2 reversed such a decrease. The ischaemic insult up‐regulated the activity of both the MAPK/ERK1/2 and phosphoinositide 3‐kinase/Akt pathways; BZA and E2 attenuated the increased activity of the ERK1/2 pathway, without affecting that of the Akt pathway. The results of the present study lend further support to the consideration of BZA as an effective and safer alternative overcoming the drawbacks of E2 with respect to improving diabetic ischaemic stroke outcome after successful reperfusion. [ABSTRACT FROM AUTHOR]