Abstract
Purpose:
To investigate the changes of retinal thickness of STZ-induced diabetic SD rats and its relationship with Kir4.1 channel in retinal Müller cells.
Methods:
1. FFA and SD-OCT was used to identify fluorescein leakage of retinal vessels and retinal thickness at 4 weeks, 8 weeks and 12 weeks after STZ-injection in the diabetes group and control group, as well as in the baseline group at the same time points. The left eyes were used as control and the right eyes were randomized into two groups: one for retinal Kir4.1 protein by Western Blot, another group for the staining of immunofluorescence for Kir4.1. 2. Daily injection of K+ channel openers (glibenclamide and barium chloride) and K+ channel inhibitors (Pinacidil group) after modeling, control group was injected with saline. 3. Changes of Kir4.1 protein in cultured Müller cell, treated with high glucose, high VEGF, and high IL6, was detected by Western blot and immunofluorescence. High glucose treated Müller cells were cultured 12h by adding the K+ channel openers (glibenclamide, barium chloride) and K+ channel inhibitors (Pinacidil) .The changes of Kir4.1 protein content detection by Westen Blot.
Results:
1.No fluorescein leakage was found until 12 weeks after modeling. 2.Retinal thickness measured by OCT at 12 weeks was thicker than control group (P<0.01)， while the retinal thickness measured by histopathological examination at 12 weeks was thinner(P<0.01). The cell number of inner and outer nuclear layer decreaded than control group at week 12(P<0.01). Barium chloride group increased and Pinacidil group decreased compared with control group(P<0.01). 3. Kir4.1 protein measured by Western Bolt and immunofluorescence was decreased at 12th Week. Kir4.1 protein of Barium chloride injection group was statistically decreased, while Pinacidil group was increased (P<0.01). 4. Compared with control group ,Kir4.1 channel protein of Müller cell cultured by high glucose, VEGF, IL-6 decreased at 16 hours (P<0.01).
Conclusions:
1. Retinal edema appeares before the retinal vascular leakage in diabetic rats at 12 weeks. 2. K+ channel protein is involved in the formation of diabetic rat's retinal edema. K + channel protein could be modulated by its opener and inhibitor. 3. High level of glucose, VEGF, IL6 could inhibited Kir4.1 protein in cultured Müller cell.