Morphometric analysis of renal cortex changes induced by diethylstilbestrol (DES) in Syrian hamsters

Estrogen-induced renal adenocarcinoma usually can be readily detected in castrated hamsters after 9 to 12 months of DES treatment. In the present study, we examined the morphological characteristics of the renal cortices of castrated hamsters that had received 3 months of DES treatment in order to describe early histological evidence of carcinogenesis induction. Twelve Syrian Golden hamsters, 8 to 9 weeks of age, were first castrated and then subjected to either subpannicular implantation of a 20 mg DES pellet (experiment group), or sham operation (controls). Morphological and 2-D morphometric evaluations were conducted sequentially on kidney histological sections. Numbers (N's) or area fractions (AF's) of renal components in the juxta-medullary junction of each kidney section were processed for morphometric evaluation. The DES treatment caused a 15% increase in kidney weight, but not body weight. Dysplastic foci associated with hyperplastic tubules were present in 67% of the left kidneys or 17% of the right kidneys of hamsters in the test group, but were absent in kidneys of controls. DES treatment decreased glomeruli N by 33% and increased the vasculature AF by 169% per examination field. DES also increased AF's of glomeruli, proximal tubules, distal tubules, and vasculature by 17, 81, 53 and 346% per nephron, respectively. Our results showed that, after the first three months of DES-treatment, hamster kidneys developed dysplastic foci and their masses were greater than controls. Increased renal components in the juxta-medullary junction region included glomeruli, tubules, and vasculature. The dysplastic foci may be sites of subsequent malignancies, whereas the increased renal mass might be a result of functional adaptation/expression to exogenous estrogen which might contribute to the carcinogenic process.