Essential fatty acid supplemented diet increases renal excretion of prostaglandin E2 and water in essential fatty acid deficient rats

Weanling male rats were fed an essential fatty acid (EFA)-deficient diet for 25 weeks and then switched to an EFA-supplemented diet for 3 weeks. Control rats received the EFA-supplemented diet for 25 weeks and then the EFA-deficient diet for 3 weeks. Throughout the last 19 weeks, the rats were housed in metabolic cages once a week for a 24-hr period. Urinary excretion of prostaglandin E₂ (PGE₂) was estimated by radioimmunoassay. Throughout a period of 12 weeks (weeks 13–24) water consumption increased ca. 60%, and urine output and PGE₂ excretion decreased ca. 45% and 70%, respectively, in the EFA-deficient rats. Feeding EFA-supplemented diet to the EFA-deficient rats for 3 weeks decreased the water consumption and raised the urine output to that observed in the controls. However, the urine output was corrected within 1 day whereas the water consumption was not corrected until the second measurement 8 days after the dietary change. The PGE₂ excretion increased more than 9-fold (from 18±8 ng/24 hr to 165±51 ng/24 hr) 1 day after EFA-supplementation, followed by a decrease to 86±29 ng/24 hr over the following 2 weeks. On the basis of the present data, it is suggested that EFA deficiency in rats causes diminished PGE₂ excretion, which can be normalized by EFA supplementation. The normalization of the urine flow may, in part, be caused by the concomitant considerable increase in endogenous PGE₂ synthesis. Presented in part at the International Symposium on Prostaglandins and the Kidney, Stuttgart, West Germany, July 1980.