The localisation of erythropoietin and erythropoietin‐receptor in the retinas of Goto‐Kakizaki rats using immunohistochemical methods

Abstract

Abstract Purpose: A number of data indicates that erythropoietin (EPO) exhibits neuroprotective and neurotrophic properties in the brain and in the retina. EPO has been recently described to be elevated in the vitreous fluid of patients with proliferative diabetic retinopathy or diabetic macular edema. The aim of our study was to describe the cellular localisation of EPO and its receptor (EPO‐R) in the mammalian retina and to evaluate whether it is altered under diabetic conditions. Methods: Retinas of eight 10 weeks old type‐2 diabetic Goto‐Kakizaki (GK) and eight age‐matched non‐diabetic control (Wistar) rats were analyzed by immunohistochemistry in the study. Sections were cut from each specimen and stained with EPO and EPO‐R specific antibodies. The labelling was visualized by the ABC method or by fluorescent antibodies. Results: Although the retinas of both groups showed similar and diffuse distribution of immunolabels, the intensity of staining was variable among the specimens. The EPO specific staining resulted a strong label in the ganglion cell layer and a less intense staining in the inner nuclear and pigment epithelium layers. The receptor specific antibody labelled the same layers and structures, but the staining intensity was more robust. There was no significant difference regarding the staining pattern of either EPO or EPO‐R between the diabetic and non‐diabetic retinas. Conclusions: Erythropoietin and erythropoietin‐receptor are present in the retinas of GK rats although there is no significant difference in this early age as compared to non‐diabetic rat retinas. Further evaluation is necessary to assess the role of erythropoietin in diabetic retinopathy.