Figure 4.

Metformin treatment for 3 months does not decrease HFD-induced retinal deficiencies. Control mice were fed standard chow for 5 months. Test mice were fed HFD for 5 months. The HFD+Met mice were given HFD for 5 months and metformin for the last 3 months. (A) Representative scotopic ERG and oscillatory potential waveforms recorded from controls, HFD-fed mice, and HFD mice treated with metformin at light intensity of 25 cd.s/m² are shown. (B) HFD-fed mice have decreased a- and b-wave amplitudes and delayed b-wave implicit times compared to those of the controls (*). The HFD+Met mice have decreased a-wave and b-wave amplitudes and delayed b-wave implicit times compared to those of controls (#). The HFD+Met mice had delayed b-wave implicit times compared to those of HFD mice (&), but there were no statistical differences between the in a-wave amplitudes, b-wave amplitudes, and a-wave implicit times in the HFD group and those in the HFD+Met group. (C) The oscillatory potential amplitudes were decreased, and implicit times were delayed in HFD-fed mice compared to those in the controls (*). The oscillatory potential amplitudes were decreased and implicit times were delayed in HFD+Met mice compared to those in the controls (#). Furthermore, HFD+Met mice had decreased OP amplitudes and delayed implicit times compared to those in the HFD-fed mice (&). (D) Maximal scotopic a- and b-wave amplitudes are unchanged in control mice over time. However, maximal scotopic a- and b-wave amplitudes of HFD-fed mice are decreased after 2 months and further decreased after 5 months of the diet regimen. Treatments with metformin for 3 months (HFD+Met) did not reverse the a- and b-wave amplitudes back to control levels. *^,#,&P < 0.05.