Abstract
AIM: To examine the expression of high mobility group box-1 (HMGB-1) and intercellular adhesion molecule-1 (ICAM-1) in the retina and the hippocampal tissues; and further to evaluate the association of these two molecules with the alterations of blood-retinal barrier (BRB) and blood-brain barrier (BBB) in a rat model of type 2 diabetes. METHODS: The type-2 diabetes mellitus (DM) model was established with a high-fat and high-glucose diet combined with streptozotocin (STZ). Sixteen weeks after DM induction, morphological changes of retina and hippocampus were observed with hematoxylin-eosin staining, and alternations of BRB and BBB permeability were measured using Evans blue method. Levels of HMGB-1 and ICAM-1 in retina and hippocampus were detected by Western blot. Serum HMGB-1 levels were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: A significantly higher serum fasting blood glucose level in DM rats was observed 2wk after STZ injection (P<0.01). The serum levels of fasting insulin, Insulin resistance homeostatic model assessment (IR(HOMA)), total cholesterol (TC), total triglycerides (TG) and low density lipoprotein cholesterol (LDL-C) in the DM rats significantly higher than those in the controls (all P<0.01). HMGB-1 (0.96±0.03, P<0.01) and ICAM-1 (0.76±0.12, P<0.05) levels in the retina in the DM rats were significantly higher than those in the controls. HMGB-1 (0.83±0.13, P<0.01) and ICAM-1 (1.15±0.08, P<0.01) levels in the hippocampal tissues in the DM rats were also significantly higher than those in the controls. Sixteen weeks after induction of DM, the BRB permeability to albumin-bound Evans blue dye in the DM rats was significantly higher than that in the controls (P<0.01). However, there was no difference of BBB permeability between the DM rats and controls. When compared to the controls, hematoxylin and eosin staining showed obvious irregularities in the DM rats. CONCLUSION: BRB permeability increases significantly in rats with type-2 DM, which may be associated with the up-regulated retinal expression of HMGB-1 and ICAM-1.