[Histopathological studies of rat kidneys following the feeding of heat-damaged proteins].

Two experiments lasting 10 vs. 8 weeks respectively were conducted in order to determine the effects of feeding heated proteins (casein + glucose, 65 degrees C for 4 days) on histopathological alterations in the kidneys of rats. Histological examinations showed enlarged epithelial cells and cell nuclei in the pars recta of the proximal tubules (inner stripe of the inner kidney cortex zone) beginning after two weeks of the test. The differences in the average size of the nuclei were significant after a feeding period of 6, 8 or 10 weeks (44 rats in the test group vs. 36 rats in the control group respectively). In this way the alterations are very similar to that which are induced by lysinoalanine. The substance causing the lesions seems not to be fructoselysine although it was present in the heat damaged diets in concentrations of 16,000-23,000 ppm but is suggested among the substances formed in the early and advanced stage of Maillard reaction.