Abstract
Purpose::
To determine if a correlation exists between the extent of basement membrane (BM) thickening in retinal and glomerular capillaries in diabetes.
Methods::
Diabetes was induced in Sprague Dawley rats with streptozotocin(STZ) injection at 55 mg/kg body weight. After six months of diabetes, rats were sacrificed, eyes enucleated, retinas and kidney cortex were isolated and processed for electron microscopy. Throughout the six month period blood glucose levels were routinely monitored and HbA1c level was monitored after three months and at the time of sacrifice. To determine BM thickness in retinal capillaries and glomerular capillaries electron micrographs were analyzed using the orthogonal intercept method. Approximately ten random images of retina and kidney cortex were analyzed from each animal (n=6).
Results::
All diabetic rats exhibited significantly increased blood glucose level and HbA1c level (5.2±1.8% vs 9.2±2.3%, p<0.05) compared to the non-diabetic control rats. Increased BM thickening was observed in retinal and glomerular capillaries (25% and 35%, respectively) in the diabetic rats compared to those of the control non-diabetic rats. The BM thickness measurements of retinal and glomerular capillaries of each individual rat showed a tight correlation (r=0.94); the BM thickness was mostly higher in the kidney glomerular capillaries compared to those of the retinal capillaries.
Conclusions::
The capillary BM thickening in the diabetic retina and kidney glomerulus appears to be strongly correlated.
Keywords: diabetes • diabetic retinopathy • retina