Type VI collagen in glomeruli of short- and- long-term experimental diabetic rats

Type VI collagen was revealed by high-resolution immunocytochemistry in renal glomeruli from short- and long-term streptozotocin-injected hyperglycaemic rats and from their age-matched normoglycaemic controls. The labellings obtained over the glomerular basement membrane and the mesangial matrix were assessed by quantitative evaluations. The labellings over the glomerular basement membrane were low and sparse in the young normoglycaemic animals but became consistent and increased in intensity with age and in both the short- and long-term diabetic animals. For the mesangial matrix, this was labelled more systematically, and its intensity increased with age and in the short-term hyperglycaemic animals. For the long-term hyperglycaemic animals, the intensities of labelling resembled those of their age-matched controls. These results indicate that type VI collagen appears to be a minor constituent of the extracellular matrix of the rat glomeruli, rather concentrated in the mesangial area in the young control animal. Concomitant with the general modifications of the extracellular matrix occurring with age and diabetes, this component increases, but apparently not with the length of the hyperglycaemic state.