RETINAL DYSFUNCTION IN EARLY STAGES OF METABOLIC SYNDROME ESTABLISHED ON A NEW EXPERIMENTAL MOUSE MODEL

PAZ, MC; BARCELONA, PF; SUBIRADA, PV; RIDANO, ME; SANCHEZ, MC

Baltimore, Maryland

Congreso; ARVOs 2017 Annual Meeting (The Association for Research in Vision and Ophthalmology); 2017

The Association for Research in Vision and Ophthalmology

Diabetic retinopathy (DR) is the most serious ocular complication associated with T2DM, which is a metabolic syndrome (MS), and one of the leading causes of secondary blindness. Although animal models of DR have helped to advance in the knowledge of this disease, these models have some limitations in to reproduce completely the retinopathy. OBJECTIVEIn this study we propose to analyze in early stages of the MS, markers of retinal vascular integrity and neuronal functionality.MATERIALS AND METHODSFor this purpose, we used C57BL/6 (WT) and Apolipoprotein E knockout mice (ApoE-KO) either fed with a normal diet (ND) or a 10% w/v fructose diet (FD) in drinking water from 2 months of age. Time-dependent kinetic studies were done from 4 to 6 months of age analyzing lipid profile, glucose tolerance test (GTT) and insulin tolerance test (ITT). For GTTs, WT or ApoE-KO with ND or FD-fed mice (n=8 per group) were fasted 5 h prior to 2g/kg body weight intraperitoneal injection of glucose. For ITTs, mice were also fasted 5 h and then intraperitoneally injected with regular human insulin (0.75U/kg body weight). Blood samples were taken from the tail vein at time 0 (before glucose or insulin injection) and at 0.5; 1 and 2 h after injections. Retinal functionality was assessed by electroretinography (ERG) at 2, 3 and 4 month of treatment in mice fully dark-adapted overnight (>15 hours). Retinal histology and immunofluorescence (IF) analysis were performed in flatmounts and cryosections, whereas vascular permeability and leakage were quantified by Evans Blue extravasations. GraphPad Prism program was employed for statistical analysis.RESULTS After 2 month of treatment, ApoE-KO FD mice showed, in addition to dyslipidemic profile, altered GTT and ITT as compared with the other groups. At this time, the ERG a- and b- wave did not show changes but the oscillatory potential (OPs) amplitudes were significantly decrease in retinas of these mice compared to ApoE-KO ND mice (p<0.05). In addition, ApoE-KO mice after 4 month with FD feeding evidenced increased vascular permeability and leakage respect to ApoE-KO ND and WT ND or FD (p<0.05). At this early stage of the metabolic disease, the GFAP expression levels were observed just in astrocytes but not in Müller glial cells demonstrating non reactive gliosis in retinas of ApoE-KO FD. CONCLUSIONThe results showed that ApoE-KO mice after 2 months of taking fructose presented metabolic alterations mimicking some features of human MS at its initial stages, accompanied by a partial neuronal that antecedent the vascular retinal dysfunction. Thus, this model could offer the opportunity to investigate DR at an early stage of the MS, which shows increasing prevalence worldwide.