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RS Tang, S Garg, R Sanchez, Q Chu, TT Lam; Akt (Protein Kinase B) and Retinal Ganglion Cell Survival in Retinal Ischemia-Reperfusion Injury in Rats . Invest. Ophthalmol. Vis. Sci. 2002;43(13):772.
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Purpose: Akt (Protein Kinase B), a member of the serine/ threonine kinase family, has been reported to promote cell survival. The goal of this study was to investigate the possible involvement of Akt in cell survival in rat retinas after retinal ischemia-reperfusion injury. Methods: Transient elevation of intraocular pressure (IOP) was induced in albino Lewis rats through cannulation of the anterior chamber with a needle connected to a saline column. IOP was maintained at 110 mmHg for 60 minutes. During ischemia, infusion of L-α-Phosphatidyl inositol-3,4,5-tris phosphate of 1µM in 0.1% DMSO (an Akt activator), and vehicle of saline in 0.1% DMSO were performed in 2 groups of rats. The animals were euthanized after 7 days. Loss of retinal ganglion cells in each experimental group was assessed by whole mount flat retinal preparations. The level of activated, phosphorylated Akt at various time points of ischemia was examined by Western Blotting. Double labeling of Akt (phosphorylated) and TdT-mediated biotin-dUTP nick end labeling (TUNEL) was also performed on the retinal sections. Results: Compared to the vehicle treated retinas, retinas treated with L-α-Phosphatidyl inositol-3,4,5-tris phosphate showed a higher number of nuclei in the retinal ganglion cell layer (RGCL). Western blotting showed a gradual increase of activated Akt at 0, 4, and 8 hours reaching a maximum level at 12 hour, and returning to normal level at 18 to 24 hours after ischemia. Double labeling studies showed that the majority of TUNEL-positive cells was Akt negative. Conclusions: Our results suggest that Akt activation may be involved in the survival of inner retinal cells in retinal ischemia-reperfusion injury.
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