Effect of erythropoietin on signal transduction pathway in rat model of retinal detachment

Background Our previous study showed that erythropoietin (EPO) protects the photoreceptor from apoptosis in retinal detachment(RD) rat,but its signal transduction pathway remains unknown. Objective The present study was to investigate the effects of EPO on signal transduction pathway in RD. Methods Twentyfour albino clean Sprague-Dawley(SD) rats were randomly divided into 4 groups.5 μl PBS was injected into vitreous cavity of rats in RD+PBS group,and 400 ng EPO(5 μl) was used at the same way in RD+EPO group.Three days later,the rats were sacrificed and the retina was isolated in each group.The expression levels of Janus kinase 2 (JAK2),p-JAK2,Akt,p-Akt,extracellular regulated protein kinase-1/2 ( ERK-1/2 ),p-ERK-1/2,signal transducer and activator of transcription 5 ( STAT5 ),p-STAT5,nuclear factor-kB (NF-sB) and p-NF-kB were detected by Western blot assay.The administration of experimental animals followed the Standard of ARVO. Results Three days after RD,the expression levels of JAK2,Akt and ERK-1,ERK-2 in retinas among normal group,RD,RD+PBS,RD+EPO groups were statistically insignificant different ( F =0.298,P =0.826 ; F =0.681,P =0.588 ; F =0.978,P=0.450;F=1.115,P=0.399 ),but the levels of p-JAK2,p-Akt,p-Erk-1 and p-Erk-2 among these 4 groups were significant difference ( F=24.435,P =0.000; F=48.163,P =0.000;F =19.092,P =0.001; F =14.393,P=0.001 ),and those in RD+EPO group was significantly higher than that in RD and RD+PBS groups( P＜0.05 ).The expression levels of STAT5 and NF-kB among the 4 groups were no significantly differences (F =1.136,P=0.391 ;F=0.696,P=0.580),but after the phosphorylation of STAT5 and NF-kB,the differences was significant ( F =14.189,P =0.001 ; F =40.103,P =0.000 ).Those in RD,RD + PBS,RD + EPO groups did not increase either (P＞0.05).Although the levels of p-STAT5 and p-NF-kB in RD,RD+PBS,RD+EPO groups were significantly higher than those in normal control group( P＜0.05 ),the level of p-STAT5 in RD+EPO group was not significantly higher than that in RD and RD + PBS groups (P ＞ 0.05 ). Conclusions PI3K/Akt and MAPK/ERK-1/2 signal transduction pathways might participate in the protecting process of EPO to photoreceptor in RD rats. Key words: Erythropoietin; Retinal detachment; Signal transduction pathway; Animal model