Kidney lesions in rats with severe long-term alloxan diabetes : I. Influence of age, alloxan damage, and insulin administration.

Alloxan diabetes was induced in rats by intraperitoneal injection or by injection into the vena cava. In 3 groups the renal vessels were clamped during, and for some minutes after, the injection. The histological appearance of the kidneys after 5, 10 and 15 months of diabetes was compared with findings in groups of untreated rats of the same age as well as in non-diabetic rats treated with insulin throughout comparable periods. The glomeruli of the alloxan diabetic rats showed changes similar but not quite identical to the human diabetic glomerulopathy. These changes were present only after diabetes of 10 months. The main difference is that the rats showed no actual nodules and that the PAS-positive hyalinosis of the arterioles, characteristic of human longterm diabetes, was absent. The glomerular changes are not age-conditioned, and the results do not suggest that the administration of insulin or direct alloxan damage played any role in inducing these lesions. Tubular damage (atrophy, dilatation) and interstitial fibrosis were most marked in rats which had not been protected against the high initial alloxan concentration in the blood by clamping the renal vessels.