Experimental Study Of The Diabetic Retinopathy Mediated By Extracellular Signal-regulated Kinase1/2

Objective To observe the pathological changes in retina from the STZ-induced diabeticSD-rats； To investigate whether ERK1/2， CPLA-2and GFAP were involved in theretinopathy of STZ-induced diabetic SD-rats by analyzing the expression and activation ofERK1/2、CPLA-2and GFAP, the inter-relationship between each other were exploredmeanwhile；To investigate the possible role and mechanism of ERK1/2signal transductionpathway in the retinopathy of STZ-induced diabetic SD-rats.Method Sixty SD(Sprague-Dewley,male)-rats were randomly divided into twogroups,diabetic group(36) and normal control group(12). Diabetic rats modle were made byintraperitomeal injection of STZ（streptozotocin,STZ）(60mg/kg) at one time,then diabetic ratswere further divided into subgroup4Week、12Week and its respective control group.the retinawere removed for research after rats were sacrificed at4W、12W, then histopathology(H＆E)、immunohistochemistry and Western blot techniques were employed to detect the expressionand quantity of ERK1/2、CPLA-2and GFAP.Results Histopathological analysis(HE) suggest that there was no obvious changes incell shape and arrangements but swelling in some different exent of every layer could beobserved after diabetes-induction12W, cells in rats retina of diabetic12W group show adecrease in number than that of the age-matched controls(P<0.05),especially ganglion cells;Theretinal thickness in diabetic rats of12W-group revealed a attenuation changes than that of theage-matched controls(P<0.05);Immunohistochemical analysis suggests that the immunostainingof GFAP occurred in the retinal vasculature including the internal limitingmembrane(ILM),cytoplasmic process of the glial cells and retinal vasculature;GFAPimmunoreactivity was significantly increased in the retinas of4-W,12-W diabetic rats comparedto that of the repective age-matched controls(P<0.05),the number of average opticaldensity(AOD) in retinas from the4-W,12-W diabetic rats and that from the repectiveage-matched controls:31967.1±13.1,72017±56.8and21519.8±16.1,23371±8.6;3.2Comparewith the retinas from4-W,12-W age-matched controls, the4-W,12-W diabetic rats revealed agreat increases in number of the GFAP-positive glial cells and in length of the cytoplasmicprocess (P<0.05); Phospho-ERK1/2could be observed in full retinas from all rats and mainlydistributed in the inner plexiform layer (IPL), the outer plexiform layer (OPL) and thephotoreceptor cells by Immunohistochemical analysis.But the retinas from12-W diabetic ratsrevealed a great increases in phospho-ERK1/2immunoreactivity compared to that from theage-matched controls;the number of AOD in retinas from the12-W diabetic rats and that fromthe age-matched controls:28502.66±2.4and12744.6±1.3; CPLA-2could be observed in fullretinas from all rats and mainly distributed in the IPL, the ganglion cell layer (GCL) andpigment epithelial layer by Immunohistochemical analysis.But the retinas from12-W diabeticrats revealed a great decreases in CPLA-2immunoreactivity compared to that from theage-matched controls; Western blot analysis demonstrated that the CPLA-2protein levels inretinas from12-W diabetic rats revealed a great decreases compared to that from theage-matched controls;the data of CPLA-2protein in retinas from the12-W diabetic rats and thatfrom the age-matched controls:224.6±12.9and275.1±21.0.Conclusions The retina shows an obvious Histopathological changes after diabetes-induction12W: swelling in some different exent of every layer and attenuationchanges in retinal thickness could be observed,cells in rats retina of diabetic12W group showa decrease in number,especially in ganglion cells; GFAP-positive glial cells and thecytoplasmic process length were increasd after diabetes-induction4W in SD-rats; ERK1/2may play some role in the STZ-induced diabetic retinopathy in SD-rats at the early time for itsexpression were inhanced after diabetes-induction12W; CPLA-2were also involved in theSTZ-induced diabetic retinopathy in SD-rats and may play some parts of the role at the earlytime for its expression were down-regulated after diabetes-induction12W.