Figure 9
Reduction in glia activation in diabetic retinas by P78. (A) The confocal images show an increase in numbers of IBA1-labeled activated microglia in the Ins2Akita diabetic retinas (AT) compared with retinas from ND mice (ND). P78 or the combination peptide treatment reduced numbers of reactive microglia in the diabetic retina. P60 had no effect on the activation of these cells. The arrow in the control (AT) indicates large amoeboid-like microglia expressing the IBA1 marker in the inner retina. (B) Higher magnification of the control from (A) showing ramifications of large microglia in the inner retina. (C) GFAP expression was detected in astrocytes and not in Muller glia cells in controls and treated and untreated samples (scale bar = 50 µmol/L). (D) Cell counts confirm that P78 reduced microglia activation in the diabetic retina by ~60% (p= 0.001). The difference between AT and P60 treatment was statistically insignificant (n = 8). Western blot (E) and densitometry measurements (F) confirm an increased in IBA1 levels and a reduction after treatment in diabetic retinas. (G) mRNA levels in the retina provide supporting evidence that P78 reduced microglia activation in diabetic conditions (p = 0.001) (n = 3). Densitometry measurements of Western blots (H) and quantitative PCR (I) indicate that GFAP protein and mRNA levels were not altered with diabetes. Comparisons among the peptide- and vehicle-treated groups where p values are not indicated in the graphs are statistically insignificant. All values are means ± SD.