MODULATION BY FISH-OIL DIET OF EICOSANOID-INDUCED ANION SECRETION IN THE RAT DISTAL COLON

Eicosanoids are involved in the mediation of inflammatory and allergic processes in the gut. In order to evaluate a potential beneficial eff ect of the diet, the effect of mediators of inflammation and of a sens itization against egg albumin on anion secretion across the colon was tested using rats fed on a diet containing 15% fish oil as compared to 15% olive oil as donor animals. Feeding on a fish oil diet significan tly reduced the response to bradykinin or phospholipase C, known agoni sts of prostaglandin-induced secretion, by about 50%. The increase in short-circuit current (Isc) induced by the phospholipase A(2) stimulat or, melittin, or by distension of the gut wall were only insignificant ly inhibited by 15-30%. Administration of egg albumin to the mucosas f rom animals sensitized against egg albumin induced an indomethacin- an d tetrodotoxin-sensitive increase in Isc. This response was, however, only insignificantly (30%) reduced by the fish oil diet. In conclusion , the effect of fish oil diet depends on the stimulus used for activat ion of prostaglandin release. This suggested that different pools of a rachidonic acid are differentially affected by the diet or that certai n stimuli for phospholipases are strong enough to overcome the effect of a reduced substrate availability. Consequently, a diet rich in poly unsaturated n-3 fatty acids may only play an adjuvant role for the the rapy of inflammatory or allergic intestinal diseases.