Therapeutic effects of phlorizin on the early stage of diabetic retinopathy in diabetic db/db mice

Objective To investigate therapeutic effects of phlorizin on the early stage of diabetic retinopathy(DR)in diabetic db/db mice. Methods The 24 db/db male mice were divided into 3 groups of phlorizin-treated diabetic group(20mg/kg of phlorizin by intragastric gavage)(DMT, n=8), diabetic group(normal saline solution by intragastric gavage)(DM, n=8), with C57BLKS/J db/m mice as the control group(CC, n=8)for ten weeks.After ten weeks, all mice were sacrificed and the retina was isolated.The specimen was embedded in paraffin wax and sliced.The sections were dyed with Sudan red and observed for retinal morphological change.Meanwhile, the expressions of GSK-3β and phospho-GSK-3β in retinas were determined by western blot. Results During the study, the CC group showed good condition.The DM group featured with polydipsia, polyphagia and a rapid increase of body weight.Phlorizin-treated diabetic mice displayed much better than the DM group.Compared with CC group, DM group showed cells proliferation in capillary endothelia and obvious thickening in basement membrane.After administration of phlorizin, the vascular lesion of central regions was remarkably improved.The expression level of phospho-GSK-3β protein was lower in DM group than in control group(76.2±15.8 vs.255.4±10.7, t=16.30, P<0.01)and was higher in Phlorizin-treated DM group(188.5±18.4)than in DM group(76.2±15.8, t=8.05, P<0.01). Conclusions Phlorizin decreases phospho-GSK-3βexpression in retina in db/db diabetic mice and suppresses the GSK-3βactivity, which leads to the protection of DR. Key words: Phlorizin; Diabetic retinopathy; Apoptosis