THE DIET AND HORMONALLY INDUCED NEPHROSCLEROSIS

Kidney lesions resembling those of chronic nephritis and nephrosclerosis developed in rats treated with L.A.P. (lyophilized anterior pituitary) and fed 'Purina', but did not develop in similar rats similarly treated and fed Purina mixed with cornstarch in a 1: 1 ratio. When synthetic diets, differing only in their relative carbohydrate and protein content, were fed, only those L.A.P.-treated rats that consumed a regimen containing 30% casein and 54% cornstarch developed nephrosclerosis. No such lesions were seen in treated rats kept on a 15% casein and 69% cornstarch diet. This difference in response is due to the protein and not to the cornstarch content of these diets; the entire amount of cornstarch was substituted by wheat starch or 15% of it was replaced by an equicaloric amount of fat, without influencing the development of kidney lesions.Various protein preparations differed in their ability to cause kidney damage. Casein, egg albumen, and wheat gluten were more damaging than lactalbumin, gelatin, or zein.The severity of nephrosclerosis caused by L.A.P. roughly paralleled the kidney hypertrophy, adrenal enlargement, and increased appetite for water, but not necessarily the food intake or the growth rate. The appearance of these renal lesions was not associated with any gross change in urine pH, but was preceded by a marked albuminuria. By the fifth day, large amounts of albumin were present in the urine of the majority of treated rats consuming the 30% casein diet. Albumin rarely appeared in the urine of treated rats consuming the 15% casein diet.These findings were discussed in relation to the literature concerning the dietary production of chronic nephritis. The procedure described in this paper greatly accelerates the development of kidney lesions, apparently identical with those shown previously to ensue on the feeding of high protein diets.