Abstract
Purpose :
Metformin is the prevalent oral prescription drug to control type 2 diabetic hyperglycemia, and is able to effectively delay the onset of secondary complications. The purpose of this study is to determine the effectiveness of metformin on HFD-induced retinal dysfunction in type 2 diabetes.
Methods :
5-week old male C57BL/6J mice were given a high-fat-diet (HFD, 60% fat calories) or standard laboratory chow (control, 10% fat calories) ad libitum over four months. After 2 months of HFD, metformin was administered via oral gavage to half the HFD mice at a dosage of 150 mg/kg daily. Body weight was monitored weekly, while resting blood glucose levels, glucose tolerance tests, insulin resistance tests, and electroretinogram (ERG) recordings were measured monthly. Pupils were dilated with 2.5% phenylephrine hydrochloride and 1% tropicamide. ERG measurements were sequentially recorded at various light intensities. The amplitudes and implicit times of scotopic and photopic a- and b-waves, as well as oscillatory potentials were recorded and analyzed using the ERGView 4.4 software (Ocuscience). The Student’s t-test and one-way ANOVA were used for statistical analyses.
Results :
After 1 month of HFD, there are significant differences in scotopic ERG a- and b- wave implicit times, as well as oscillatory potentials between the control and HFD-mice. After 2 months of HFD, there are significant statistical differences in scotopic ERG a- and b-wave amplitudes, implicit times, and oscillatory potentials between the control and HFD-mice. However, the differences in ERGs between HFD and control gradually decreased after 3 and 4 months of HFD regimen. Metformin treatments for only 1 month have significantly reduced body weights and resting blood glucose levels and improved glucose tolerance and insulin resistance in HFD mice. However, continued treatments with metformin did not specifically enhance retinal function.
Conclusions :
Our results showed that HFD caused a decrease in ERGs after 2 months of feeding regimen, but eventually, the ERG a- and b-waves in HFD mice stabilized and seemed recovered to the control levels, even though their blood glucose levels were still higher than 200 mg/dL. Although Metformin was able to reduce body weight and blood glucose levels, it did not recover the retinal function.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.