Relation Between NF-kappa B in the Retina and Pathologic Changes of Retinal Microvascular Ultrastructure in Diabetic Rats

Objective:To investigate the change of the activity of nuclear factorκB(NF-κB) and pathologic changes of retinal microvascular ultrastructure in diabetic rats,as well as their relationship.Methods:Fortyeight SD rats were randomly and equally divided into normal control group and diabetic group.Diabetes was induced in SD rats by streptozotocin(STZ) intraperitoneal injection in diabetic group.Retinal paraffin sections were stained by immunohistochemical(SP) method to investigate the changes of the activity of NFκB and the retinal microvascular ultrastructure were observed under transmission electronic microscope at the first,third and fifth month of diabetes duration.Results:In diabetic retina,NF-κB predominantly expressed in the nuclear of the retinal ganglion cells,vascular endothelial cells,the inner and the outer nuclear layer cells in the diabetic group.In the normal control group,NF-κB was expressed slightly in the cytoplasm of the retinal ganglion cells.Moreover,the activity of NF-κB was enhanced gradually with the course of diseases.In the normal control group,the heterochromatine distributed evenly in both the retinal microvascular endothelium and the pericyte,the shape of organelle and nucleus were normal,the structure of basement membrane displayed clear and integrity.In the diabetic group,the structure of retinal microvascular endothelia and pericytes were normal on the whole within one month;at the 3rd months there was edema of endothelium,swelling and degenerated mitochondrion,limited nuclear chromatin in retinal microvessels;at the 5th month there was swelled and deformed endothelium in retinal microvessel,vascular lumen was obviously constricted and even blocked,inner structure of pericytes disappeared,only a bit of organelle remained,and basement membrane was obviously thickened.Conclusion:Pathologic changes of retinal microvascular ultrastructure in the rats occurred after three months of diabetes.NF-κB was activated before any pathologic changes of microvascular ultrastructure appearing in diabetic retina,and its activity is enhanced gradually with the course.NF-κB may play an important role in the onset and the development of diabetic retinopathy,and these results may provide a new way to prevent and delay it.