Role of Phosphatidylinositol-3 and Mitogen-Activated Protein Kinases on Rat Retinal Cells Size and Neurite Outgrowth in the Absence and in the Presence of Taurine

This study examined the effect of phosphatidylinositol-3 protein kinase (PI3K), LY 294002 and wortmannin, and of mitogen activated protein kinases (MAPK) inhibitors, PD 98059 and SB 203580, on rat retinal cells size and neurite outgrowth in the absence and in the presence of taurine. Isolated cells were cultured for 5 days in minimal essential medium containing taurine (4 mM) and the inhibitors at different concentrations (2.5, 10, 20, 25 M). Size of ganglion cells was measured and outgrowth was evaluated by the length of the largest neurite (m), in cells less than 12 m and 12 m. The inhibition of IP3K and MAPK modifies the cell size and neuritic growth of retinal cells and the trophic effect of taurine on these parameters. The effect of the inhibitors, probably acting directly or at other cellular levels, indicates that the regulation of outgrowth by phosphorylation is a complex and dual process. These results contribute to the understanding of mechanisms involved in maintenance of retinal cells, and could be useful for possible therapeutic targets in retinopathies of various origins such as glaucoma, macular degeneration, among others.