EFFECT OF DIETARY SOY PROTEIN AND GENISTEIN ON DISEASE PROGRESSION INMICE WITH POLYCYSTIC KIDNEY-DISEASE

The effects of feeding a soy protein isolate or genistein, an isoflavo noid present in soy protein, on cyst development were examined in the DBA/2FG-pcy (pcy) mouse, an accepted animal model of polycystic kidney disease, before the appearance of clinical symptoms, In study 1, 60-d ay-old male pcy mice were evenly divided into two groups and fed semip urified diets, based on casein or a soy protein isolate (15 g protein/ 100 g diet) for 90 days, In study 2, the animals were fed a casein-bas ed diet (25 g casein/100 g diet) with or without genistein (0.05 g/100 g diet) for 60 days, In study 1, total kidney weight and kidney weigh t relative to body weight were significantly reduced (by 24% to 25%) i n the animals fed the soy protein-based diet, relative to the casein-f ed group, as was kidney water content (by 38%), In addition, mean cyst volume, as measured by morphometry, were lower (by 25%) in kidneys fr om the soy protein-fed group, No differences were found between these two groups with respect to final body weight, plasma creatinine, and p rotein content; however, plasma urea values were significantly lower i n the soy protein-fed animals, Genistein supplementation of a casein-b ased diet in study 2 did not reduce the renal enlargement and cyst dev elopment associated with progression of polycystic kidney disease, The se results suggest that soy protein is effective in retarding cyst dev elopment in the pcy mouse and that this beneficial effect may be unrel ated to its genistein content. (C) 1998 by the National Kidney Foundat ion, Inc.