Evaluation of apoptosis and cell proliferation in experimentally induced renal cysts

Cell proliferation and apoptosis in renal cysts induced by streptozotocin, alloxan and ferric-nitrilotriacetate were investigated in rats. In the kidn eys of all treated animals dilated tubules at the cortico-medullary region, large cysts, glomerular cysts and tubular dilation in the medullary area w ere found. Both cell proliferation and apoptosis were increased in the epit helium of the non-dilated tubules, in the mesangial and interstitial cells. Cells lining the dilated tubules or cysts demonstrated apoptosis but their proliferating activity was low. By calculating the proliferation-apoptosis ratio we found that alloxan did not change the balance between the two mec hanisms. Meanwhile streptozotocin resulted in an increased apoptosis and fe rric-nitrilotriacetate in an increased cell proliferation. p53 expression m ight be responsible for the uncontrolled proliferation in rats treated with ferric-nitrilotriacetate as this oncoprotein was diffusely present in tubu lar cell nuclei. The observed apoptosis seemed to be independent of bcl-2 o ncoprotein expression. We assume that the initial factor in such cystogenes is should be a cellular injury due to direct toxic or to the diabetogenic e ffect of the drugs. The latter is more likely as all the animals were hyper glycemic and insulin treatment following administration of streptozotocin p revented the morphologic changes.