EFFECTS OF DIETARY-PROTEIN RESTRICTION AND OIL TYPE ON THE EARLY PROGRESSION OF MURINE POLYCYSTIC KIDNEY-DISEASE

A paucity of research data exists on the potential for early dietary modification to directly retard cystic growth and proliferation in polycystic kidney disease (PKD). We have therefore examined the relative effects of dietary protein levels and oil type on the progression of disease in a murine model of PKD. In the first study, weanling DBA/2FG-pcy (pcy) mice were fed either a normal (NP), 25%, or low (LP), 6%, casein diet with 10% of either sunflower seed oil (SO) (containing n-6 fatty acids), or fish oil (FO) (containing n-3 fatty acids), in a 2 x 2 design. At the end of the dietary treatment, kidney weight relative to body weight was higher in mice on the NP diets. In addition, kidney phospholipid to kidney weight (mu-mol/g) was lower in pcy mice on NP diets, indicating that the increased kidney size was largely due to increased cyst development. Replacement of dietary SO with FO resulted in alterations in renal phospholipid fatty acid compositions: 18:2 n-6, 20:4 n-6, and 22:5 n-6 were lower, and 20:5 n-3, 22:5 n-3. and 2:6 n-3 were higher in FO-fed animals. No effect of dietary lipid type on disease progression was noted, however. In a second study, morphometric analysis revealed an 11% lower percentage cyst area and a 46% lower total cyst area (mm2) in kidney sections derived from mice on LP diets compared to NP diets. These results indicate that early dietary protein restriction in PKD prior to clinical manifestation of symptoms of the disease may have a significant impact on the pathogenesis of PKD.