Relationship of leukocyte adhesion to iris blood flow in diabetic rats : role of vitamin c

Abstract

To study the effects of vitamin C on the relationship between leukocyte adhesion and iris blood flow in diabetic rats the animal model of streptozotocin (STZ)-induced diabetic rats (a single intravenous injection of STZ; 55 mg/kg BW) was used. Male Wistar Furth rats weighing 200-250 g were divided randomly into three groups of control (CON), streptozotocin (STZ) and streptozotocin supplementation with vitamin C (STZ-Vit C). The supplementation of vitamin C was performed by allowing the animals free assessed to drinking water added 1g/L of ascorbic acid (Sigma, Chemical Co., USA). The experiments were performed at 8, 12, 16, 24 and 36 weeks after injection of STZ. On the day of experiment, body weight (BW), blood glucose (BG), glycosylated hemoglobin (HbA1c), plasma vitamin C, systolic blood pressure (SBP), diastolic blood pressure (DBP), iris blood-flow perfusion, and leukocyte-endothelial cell interaction were evaluated for all groups. At the end of each experiment, the eye was isolated immediately for malondialdehyde measurement and for histological examination. The results showed that all groups of 8, 12, 16, 24 and 36 weeks STZ groups had the significantly increase in blood glucose (BG ), glycosylate d hemoglobin (HbA1c) and MDA, but decrease in BW and plasma vitamin C levels as compared to their age-match control groups. However, STZ-Yit C was significantly decreased in blood glucose (BG), glycosylated hemoglobin (HbA1c) and MDA but increased in BW and plasma vitamin C levels as compared to STZ group. However, only on 36 weeks that significant of BG C result was observed. Moreover, all groups of 8, 12, 16, 24 and 36 weeks STZ groups have the significantly decrease in regional iris blood-flow perfusion but increase in number of leukocyte adhesion. STZ-Yit C was significantly increase regional iris blood-flow perfusion but decrease leukocyte adhesion as compared to STZ group only in 24 and 36 week groups. The result of relationship between iris blood-flow perfusion (AU) and leukocyte adhesion (cellsper field of view) on postcapillar venule of all five monitored time points of diabetic rats demonstrated that the correlation was able to represent by the linear equation of y = -0.447x+32.80, r = -0.317 (p < 0.034). However, the correlation between leukocyte adhesion and iris blood-flow perfusion on STZ-Vit C has become more correlation with r = -0.517 (p < 0.001), and by the equation of y = -1.862x+47.10. In conclusion, the present study has demonstrated that the endothelial dysfunction induced by diabetes has been resulted to the increase in leukocyte adhesion and to the decrease in regional iris blood -flow However, the correlation between those two parameter s indicated that leukocyte vasa-occluded was not simply major cause of abnormalities of such iris blood -flow perfusion. Interestingly, this finding has suggested that not only vitamin C supplementation can prevent the diabetic-induced endothelial impairment but also might be a great therapeutic agent for preventing retinopathy as a consequence of ischemia in diabetic eye.