Neurovascular protection conferred by 2-BFI treatment during rat cerebral ischemia

Stroke is caused by vascular dysfunction and currently there are no effective therapeutics to stroke induced brain damage. In contrast to an intense emphasis on neuroprotection, relatively few studies have addressed means of vascular protection in cerebral ischemia. Here we discovered that the ligand to immidazolin receptor, 2-BFI, not only provided potent neuroprotection during middle cerebral artery occlusion in rat, which confirmed our previous reports, but also protected the integrity of the cerebral vasculature. Treatment with 2-BFI twice daily after the occlusion of the middle cerebral artery for 14 d significantly improved the neurological deficits, reduced brain infarction, and importantly, protected the cerebral vasculature as evidenced by the increased expression of an endothelial marker, von Willebrand factor, and better preservation of the cerebral vasculature, as viewed under a confocal microscope on rat brain perfused with FITC-labeled dextran. These results indicated that 2-BFI contributes to protection of neurovasculature. Understanding the molecular mechanisms could eventually lead to development of more effective therapies for stroke.

Notch signaling and neurogenesis in normal and stroke brain

Adult neuronal stem cells (NSCs) hold great promise for brain repair because of their unique location within the central nervous system, their potential to proliferate and to differentiate into all major neural lineages, and their ability to functionally incorporate into existing neuronal circuitry after stroke. Nevertheless, the ability to exploit these cells for therapeutic purposes is hampered by the lack of knowledge about the signals that control the generation of a functional neuron from adult NSCs after stroke, particularly in the aged brain. Therefore, to further define the regulatory mechanisms that underlie neurogenesis after stroke, it is critically important to develop future NSC-based repair strategies. Notch signaling defines a fundamental pathway controlling cell fate acquisition. Studies have shown that Notch signaling pathways play critical roles during the maintenance, proliferation, and differentiation of NSCs in the developing brain. Recent evidence shows that Notch1 signaling is conserved in the regulation of adult neurogenesis. Here we summarize current knowledge about the role of Notch signaling in the regulation of neurogenesis in the normal and stroke brain.

Attenuation of ischemia-induced rat brain injury by 2-(-2-benzofuranyl)-2-imidazoline, a high selectivity ligand for imidazoline I(2) receptors

OBJECTIVE

The aim of this study was to determine whether 2-(2-benzofuranyl)-2-imidazoline, an imidazoline I(2) receptor ligand, could protect against cell death from brain injury and improve the functional outcome after focal cerebral ischemia in rats.

METHODS

Transient focal ischemia was induced by suture occlusion of the middle cerebral artery. Rats were intraperitoneally treated with a vehicle, 2-(2-benzofuranyl)-2-imidazoline or idazoxan immediately after focal ischemia. Infarct volume was assessed by 2,3,5-triphenyltrazolium chloride staining and neurobehavioral deficits were monitored. The volume of cell death in the penumbra after ischemia was determined by immunostaining using anti-cleaved caspase-3 antibody and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL).

RESULTS

Both 2-(2-benzofuranyl)-2-imidazoline and idazoxan significantly improved the neurological score compared with the vehicle at 24 hours after focal ischemia. Treatment with 2-(2-benzofuranyl)-2-imidazoline or idazoxan also significantly reduced infarct volume and the number of both caspase-3- and TUNEL-positive cells in the penumbra compared with vehicle-treated rats (p<0.01 and p<0.05, respectively).

CONCLUSION

The results suggest the neuroprotective role of 2-(2-benzofuranyl)-2-imidazoline and idazoxan in focal cerebral ischemia, and may therefore represent useful targets for developing new treatments for stroke.