R/M hypoglycemia-induced dendritic oxidative injury and microglial activation was reduced by the NADPH oxidase inhibitor, apocynin. (A) Fluorescent images show MAP2 (green) and 4HNE (red) antibody stained stratum radiatum (SR) of hippocampal CA1 area. The 4HNE intensity in the dendritic area after R/M hypoglycemia (R/M HG) is substantially increased in diabetic and non-diabetic rats. The NADPH oxidase inhibitor, apocynin (Apo), reduced 4HNE intensity is much higher in the diabetic and in the non-diabetic rats, which suggests R/M hypoglycemia-induced oxidative injury in the dendritic area of hippocampus is mediated by NADPH oxides activation. SP, Stratum pyramidalae. Bar = 100 μm. (B) Bar graph represents quantitated 4HNE fluorescent intensity from the SR area of hippocampal CA1 area. Data are mean + s.e.m.; n = 7, * P < 0.05. (C) Brain sections were harvested at 1 day after the last episode of moderate hypoglycemia and immunostained with CD11b. R/M hypoglycemia-induced microglial activation in the hippocampus is apparent in both non-diabetic and diabetic rats. Apocynin (Apo) treatment reduced microglia activation in the diabetic or in the non-diabetic rats. Scale bar = 100 μm. (D) Quantification of microglial activation was performed from hippocampal CA1 pyramidal area. Microglial activation is quantified based on morphological change and intensity of CD11b immunostaining. Data are mean + s.e.m.; n = 5, * P < 0.05.