The Effects of Exercise and High-Fat Diet on Retinal Vessel Diameters in Mice

Background: Studies in human beings showed that the retinal microcirculations were affected early in the development of atherosclerosis. A lower retinal Arterioleto-Venule Ratio (AVR) is known to be associated with an increased prevalence of hypertension, diabetes and obesity.Methods: Retinal vessel diameters were assessed in 36 male mice (C57BL) by dividing them into three groups of twelve animals each: an exercise group, a highfat diet group and a control group. In total eight weeks of intervention the exercise group trained five times a week on an open treadmill and for voluntary running a running wheel was provided. The high-fat diet group was fed with 60%kcal%fat food and their insulin resistance was evaluated by a glucose tolerance test before and after the intervention, respectively. In order to analyze the body composition of each animal we took advantage of Echo medical system Magnetic Resonance Imaging (EchoMRI). Before and after the intervention, the retinal arteriolar and venular diameters were measured using a rodent camera device and adapted software (Imedos systems UG, Jena, Germany) for retinal vessel analysis in mice.Results: The exercise group showed an increased running distance after the intervention and an enhanced oxygen uptake at a higher running speed compared to the control. The high-fat diet group had a significant higher fat mass after the fat diet compared to the control animals (P=0.001). The glucose tolerance test showed insulin resistance in the high-fat diet group. The Central Retinal Arteriolar Equivalent (CRAE) did not reveal any effect within as well as between the groups at time points t2 (baseline), t3 and t4. There was a significant difference in the Central Retinal Venular Equivalent (CRVE) level between the exercise and the control group at time point t2 (P=0.006) and also between the control and the highfat diet group at t2 (P=0.014). The difference was no longer detectable at time points t3 and t4. There was no significant effect from the intervention on AVR (P=0.856, to the baseline t2 P=0.776).Conclusion: The effect of eight weeks training and a high-fat diet intervention could not be verified on the basis of retinal vessels in mice.