DIETARY SUPPLEMENTATION WITH OLIVE OIL INFLUENCES AMINOPEPTIDASE ACTIVITIES IN MICE

We compared the effect of a low fat diet and an high fat diet containi ng olive oil (20% wt/wt) on soluble and membrane-bound aminopeptidase activities, in serum and selected tissues of male mice. After ten week s of feeding, serum total cholesterol was determined colourimetrically . Alanyl-, arginyl- and cystinyl-aminopeptidase activities were measur ed fluorometrically using arylamide derivatives as substrates. Mice fe d with the olive oil-supplemented diet had higher rates of weight gain than controls from the second week of feeding. Serum total cholestero l concentrations were higher after feeding the olive oil diet than aft er feeding the control diet. In serum, the olive oil-fed group had sig nificantly higher arginyl-aminopeptidase activity levels than controls . Soluble alanyl-and arginyl-aminopeptidase activities increased signi ficantly in the brain, adrenal gland and testis of olive oil-fed anima ls. Soluble cystinyl-aminopeptidase activity increased significantly i n testes and liver and decreased in the adrenal glands of olive oil-fe d mice. There was a significant decrease in membrane-bound cystinyl-am inopeptidase activity in the adrenal glands of olive oil-fed mice. The se findings show that a diet supplemented with olive oil modifies cert ain aminopeptidase activities in specific tissues. The results may ref lect functional modifications in susceptible endogenous substrates. (C ) 1998 Elsevier Science Inc.