Effects of fish oil on glomerular function in rats with diabetes mellitus.

The mechanisms responsible for hyperfiltration in diabetes mellitus (DM) as well as for the initiation and progres- sion of diabetic nephropathy are not fully elucidated. Enhanced prostaglandin E2 (PGE,) production has been invoked in the former and thromboxane (TXB2) and hyperlipidemia in the I&- ter. Fish oil (F0)-enriched diets can favorably alter eicosanoid: synthesis and serum lipid profiles. We therefore examined the effects of a FO-enriched diet on glomerular filtration (GFR), proteinuria, glomerular eicosanoid production, and serum lipids in rats with streptozotocin-induced DM (STZ-DM). Groups of 5-8 rats with STZ-DM were maintained on low insulin and then pair-fed with isocaloric diets enriched with either FO (20 % w/w) or beef tallow (BT, 20 % w/w). GFR was determined in the same animals at onset of diet and after 8 and 20 weeks on the respective diets by ('*C)inulin clearance using im- planted osmotic minipumps each time. Significant hyperfiltra- tion was present initially and GFR did not change on either diet for 20 weeks, in spite of a significant and greater than 50% decrease in all prostaglandins (PGE,, TXB2, PGF,,, 6-keto, PGF,,) produced by glomeruli isolated from DM/FO as com- pared to DM/BT or control rats. FO diet completely corrected the hypertriglyceridemia of diabetes and significantly reduced the mild and early proteinuria of DM. The decrease in pro- teinuria and the correction of hyperlipidemia of DM by a FO- enriched diet may be beneficial in the long term not only for the development of diabetic glomerulopathy, but also for the ac- celerated atherosclerosis of DM. - Sinha, A. K., L. A. Schar- Schmidt, R. Neuwirth, H. Holthofer, N. Gibbons, C. M. Ar- beeny, and D. Schlondorff. Effects of fish oil on glomerular function in rats with diabetes mellitus. J Lipid Res. 1990. 31: 1219-1228.