Smmnm'y.A quantitative morphological study of the mesangial regions has been performed on the kidneys of two groups of insulin treated diabetic rats 6 months after the induction of diabetes. In one group reasonably good control of plasma glucose levels (182 + 20 (SD) rag/100 ml at 0800 h; 95 + 35 mg/ 100 ml at 2300 h) was achieved. This group showed no mesangial changes when compared to a nondiabetic control group. In the second diabetic group poor control was intended (plasma glucose 452 +_ 41mg/100ml and 555 _+ 86mg/100ml respectively). The following differences were noted when this group was compared to the non-diabetic controls and to the rats in which the blood glucose was wellcontrolled: 1. Increase in total mesangial volume per glomerulus by 42% and 38% (2p = 0.025 and 0.037); 2. Increase in the total amount of basement membrane-like material (BMLM) per glomerulus by 30 and 27% (2p = 0.030 and 0.046); 3. Increase in the total mesangial cell volume per glomerulus by 46 and 43% (2p = 0.033 and 0.048); 4. Increase in volume of electron dense material in the BMLM by about 200% compared to both groups (2p ---0.001 and 0.0003). The study has shown that the mesangial regions also are involved in the diabetic glomerulopathy of experimental diabetes. The morphological changes including increased amounts of basement membrane material are prevented by proper glycaemic control.Key words: Mesangial region, streptozotocin diabetes, glucose control in rats, diabetic glomerulopathy, stereology, insulin treatment.It has previously been shown that kidneys and glomeruli become enlarged over a 6 months period in rats with constant high plasma glucose levels [27].Glomerular basement membranes (GBM) were also significantly thicker than in non-diabetic control rats [28]. There is also evidence of mesangial changes in experimental diabetes in the rat [11,13,19,34,35], similar to those found in humans [21,23,24,35]. The mesangial changes due to experimental diabetes are described as an increase of the mesangium, with increased amounts of basement membrane-like material (BMLM). The mesangial regions also become strongly reactive to periodic acid-Schiff (PAS) and with the immunofluorescent technique a positive reaction to immunoglobulin and complement is seen.Consequently, the experimental diabetic rat was considered an acceptable model for studying the prevention of diabetic mesangial changes using morphometric techniques. The cationic stain Alcian Blue [31], which reveals the surface coat of the glomerular cells [2], is also bound to the mesangial regions of diabetic and non-diabetic rats [25] and this electron microscopic histochemical technique was also used in the present study.
Material and MethodDetailed description of the animals, their treatment and the tissue sampling procedure has been given previously [27,28]. In summary, streptozotocin diabetes was induced by administrating 90 mg/kg intravenously. Three groups of female Wistar rats were used. In one group of 8 streptozotocin diabetic rats good diabetic control was plan...