Young Diabetic Rats Research Articles

Glomerular Alterations in Experimental Diabetes of the Rat

To detect structural glomerular alterations in the early stages of diabetes mellitus glomeruli from young streptozotocin diabetic rats were studied by light microscopy with morphometric methods 2, 8, 12 and 24 weeks after induction of diabetes. It was found that there is a marked increase in the percentage mesangial surface as compared with the control animals already two weeks after induction of diabetes. The relative mesangial surface fraction was greater in the diabetic animals than in the controls at all test times. It was also demonstrated that the endothelial cell count was reduced in the diabetic animals in the first few weeks of the study. High-grade glycosuria and proteinuria were likewise observed in the diabetic animals. Hence the mesangium appears to be one of the glomerular structures which shows the first changes in the initial stages of diabetes mellitus. Possibly the most likely cause of the changes based on the present study is the diabetic metabolic state (or the insulin deficiency).

Evolution of Glomerular Lesions in Rats with Spontaneous Diabetes

The development of glomerular lesions associated with ageing was investigated electron microscopically in rats with spontaneous diabetes. In young diabetic rats at eight weeks of age, there was no particular difference in ultrastructure from age-matched control rats showing an even contour of glomerular basement membrane, whereas in the diabetic rats at 12 weeks of age thickening of basement membrane with irregular protrusion of the epithelial side of lamina densa and accumulation of basement membrane-like materials in the mesangial regions could be observed. After 16 to 24 weeks of age in the diabetic rats, hemispherical thickening in addition to diffuse thickening of glomerular basement membrane was noted. The thickening of basement membrane was due to widening of lamina densa consisting of accumulation of basement membrane-materials on the epithelial side of the lamina densa, all the way along the peripheral capillary loops. These features of glomerular lesions in the diabetic rats were progressively accentuated accompanying ageing. The early glomerular ultrastructural alterations in the diabetic rats were very compatible with those seen in the elder control rats. The results indicated that the development of diabetic glomerulopathy might be destined very early in life of the spontaneously diabetic rats supposedly by their diabetic genes.

Lipid class and fatty acid composition of rat brain and sciatic nerve in alloxan diabetes.

Quantitative analysis of major lipid classes and the fatty acids carried out on lipid extracts of brain from young and adult alloxan diabetic rats revealed decreases in total lipid, cholesterol, the more polar cerebroside, and phospha-tidylethanolamine in brain from young diabetic rats. No significant changes in lipid class composition were found in brains from adult rats with alloxan diabetes. No significant changes in fatty acids were detected in the total brain lipids of young or adult rats as a result of alloxan diabetes. In contrast, similar studies on the lipids of sciatic nerve revealed an increase in cholesterol balanced by a decrease of triglycerides in young rats and a decrease of total lipid and the more polar cerebroside only in adult rats with alloxan diabetes. Compared to normal rats, total lipids from sciatic nerves of young alloxan diabetic rats showed relative decreases in palmitate (16:0), oleate (18:1), and linoleate (18:2) with increases in stearate (18:0), eicosanoate (20:0), eicosenoate (20:1), arachidonate (20:4), docosanoate (22:0), docosapentaenoate (22:5), docosahexaenoate (22:6), lignocerate (24:0). In lipid extracts from sciatic nerves of adult diabetic rats, only oleate (18:1) was increased and linoleate (18:2) decreased compared to normal.

Formation of Polyols by the Lens of the Rat with ‘Sugar’ Cataract

CATARACT (opacity) of the lens inevitably develops in young rats fed xylose or galactose1, or in young diabetic rats if the blood glucose is maintained at a level above 2.5 mgm./ml. blood2. These three forms of cataract which resemble each other closely in clinical and histological appearance, are known as ‘sugar’ cataracts because in all cases there is a raised level of monosaccharides in the blood. The early metabolic changes within the lens, which lead to gradual loss of transparency, are unknown. It was decided to examine the carbohydrates and their derivatives in normal and cataractous lenses to see if changes occurred in ‘sugar’ cataract, and if so whether there was any similarity in this respect between the three forms of cataract.