| Objective: In recent years, the concern on dyslipidemia and obesity that can lead to serious angiocardiopathy and cerebrovascular disease seriously effecting people's health is growing. The researchers found that dyslipidemia, obesity also affect the retinal microvascular. Currently, the specific mechanism of hyperlipidemia and obesity induce the injury of retinal microvascular is not clear. This study is to explore long-term high-fat feeding SD rats retinal microvascular changes and the gene expression changes on hypoxia-inducible factor (HIF-1), vascular endothelial growth factor (VEGF), intercellular adhension molecule (ICAM-1) and transforming growth factor (TGF-β) and the effect of pioglitazone.Methods: 8-week-old male SD rats were randomly divided into 3 groups: normal control group(NC group), high-fat diet feeding group(HF group) and the pioglitazone treated group(HP group). Respectively to the normal diet, high-fat diet. At the same time, HP group were given lavage of pioglitazone (15 mg·kg-1·d-1 dose), NC group, HF group were given distilled water lavage, once a day. 24 hour urine of rats were collected and quantitative of 24 hour urinary albumin were determined at the end of 32 weeks. After 32 weeks feeding, insulin sensitivity was measured by euglycemic hyperinsulinemia clamp. The other rats were killed. we determined fasting blood glucose(FBG), fasting serum insulin(FINS), fasting serum free fatty acids(FFA)and triglyceride(TG). The retinal microvascular digest preparation and immunohistochemistry were made in one eyeball. The other eyeball separated the retinal tissue and the expression of HIF-1, VEGF, ICAM-1 and TGF-βmRNA in retinal tissue were detected by Real time-PCR. All the data were dealt with SPSS 10.0.Results:1 From the beginning of the second week in the experiment, HF group began to gain weight. At the 32 weeks, the weight, visceral fat weight and weight percentage of visceral fat of HF group and HP group rats were significantly higher than NC group (P <0.01). The fasting blood glucose, insulin, free fatty acid, triglyceride, quantitative of 24 hour urinary albumin in HF group were higher than NC group, the difference of statistics was significant; HP group were lower than HF group.2 Euglycemic hyperinsulinemia clamp: The glucose infusion rate(GIR)during euglycemic hyperinsulinemia clamp in HF group was significantly decreased than in NC group, and steady-state average GIR is just (4.8±1.2) mg.min-1.kg-1, The NC group steady-state average for the GIR is (11.3±1.7) mg.min-1.kg-1, the difference was significantly, while the HP group is (10.1±1.5) mg.min-1.kg-1.3 Retinal microvascular digest preparatin-PAS staining showed that retinal capillary in NC group were regular, arteriovenous take shape were more straight, the diameter of capillary were more uniform. The distribution of endothelial cells and pericytes were orderly distribution, morphology rules, pericyte/endothelial cell ratio is 1.082. The capillaries of retina in HF group were irregular tubes. Hyperplasia of endotheliocytes and decreased pericytes were found and the shape of cells were not regular.Many aggregation and adhension of leucocytes to capillary walls, acellular capillaries, and opoptosis of pericytes were found in HF group.But did not found the pericyte ghosts and microaneurysms, pericyte/endothelial cell ratio is 0.48; Pioglitazone intervention can reverse these changes. pericyte/endothelial cell ratio is 0.755.4 Immunohistochemical staining of retinal capillary showed that retinal vascular with a brown positive, artery and vein were stained deep and the microvascular with a shallow staining. The expression of HIF-1 and VEGF in HF group was significantly enhanced compared with NC group. The expression of HIF-1 and VEGF in HP group was significantly reduced compared with HF group. At the same time, The expression of ICAM-1 and TGF-βin HF group was significantly enhanced compared with NC group. The expression of ICAM-1 and TGF-βin HP group was significantly reduced compared with HF group, the difference of statistical was significantly.5 The gene expression of HIF-1 was significantly increased 34.15% in the HF- group than in NC group,the HP group were reduced 10.65% compared with HF group. The expression of VEGF was significantly increased 390%, the HP group were reduced 82.6% compared with HF group. The expression of ICAM-1, TGF-βmRNA in HF group were increased 20.6%, 76.2% and the HP group were reduced 12.3%, 40.6% compared with HF group.Conclusion:1 After 32 weeks feeding, the weight, visceral fat weight and weight percentage of visceral fat were significantly higher in HF group and HP group rats than NC group. The euglycemic hyperinsulinemia clamp showed insulin resistance significantly in HF group. The fasting blood glucose, insulin, free fatty acid, quantitative of 24 hour urinary albumin in HF group were higher than NC group. The animal model of high-fat obese rats was established. By which the rat model of high-fat and obesity can be established. This rat model with hyperlipidemia, obeisity and insulin resistance.2 Retinal microvascular digest preparatin-PAS staining showed that hyperplasia of endotheliocytes,decreased pericytes, adhension of leucocytes to capillary walls and acellular capillaries were found. It was indicated that the long-term high-fat feeding can induced the damage of retinal microvascular.3 Result of immunohistochemistry and Real-time PCR suggesting that The retinal damage of high-fat obese rats which the long-term high-fat diet induced may be related to the activation of cytokine(HIF-1, VEGF, ICAM-1 and TGF-β).4 Pioglitazone as peroxisome proliferator-activated receptor (PPAR) -γagonist might improve insulin resistance, protect endothelial cells and reduce the expression of cytokines(HIF-1, VEGF, ICAM-1, TGF-β) to prevention and mitigation the damage of retina.
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