The effects of erythropoietin on RhoA/Rho-associated kinase expression in rat retinal explants cultured with glutamate

Abstract

The aim of this study was to investigate the effects of erythropoietin (EPO) on RhoA/Rho-associated kinase (ROCK) expression in rat retinal explants cultured with glutamate. After the retinal explants were cultured in serumfree R16 nutrient medium for 24 h, the retinal explants were divided into control (R16 nutrient medium), glutamate (R16 nutrient medium containing 5 mM/l glutamate) and glutamate + EPO (R16 nutrient medium containing 5 mM/l glutamate and 6.0 U/ml EPO) groups, and culturing was continued for another 72 h. The mRNA and protein expression of total RhoA, ROCK1 and ROCK2 in the retinal explants was examined by RT-PCR and western blotting, and active RhoA in the retinal explants was detected via GST-RBD binding and immunoblotting with an antibody specific to active RhoA. The total RhoA mRNA and protein expression did not differ substantially between the control, the glutamate and the glutamate + EPO groups. The glutamate increased the active RhoA, ROCK1 and ROCK2 expression in cultured retinal explants (P<0.05), whereas the expression of active RhoA, ROCK1 and ROCK2 in the glutamate + EPO group was significantly lower than that in the simple glutamate group (P<0.05) and similar to that in the control group. In conclusion, EPO downregulates active RhoA, ROCK1 and ROCK2 expression in retinal explants cultured with glutamate.