Dietary supplementation with olive oil influences aminopeptidase activities in mice

Abstract

We compared the effect of a low fat diet and an high fat diet containing olive oil (20% wt/wt) on soluble and membrane-bound aminopeptidase activities, in serum and selected tissues of male mice. After ten weeks of feeding, serum total cholesterol was determined colourimetrically. Alanyl-, arginyl- and cystinyl-aminopeptidase activities were measured fluorometrically using arylamide derivatives as substrates. Mice fed with the olive oil-supplemented diet had higher rates of weight gain than controls from the second week of feeding. Serum total cholesterol concentrations were higher after feeding the olive oil diet than after feeding the control diet. In serum, the olive oil-fed group had significantly higher arginyl-aminopeptidase activity levels than controls. Soluble alanyl- and arginyl-aminopeptidase activities increased significantly in the brain, adrenal gland and testis of olive oil-fed animals. Soluble cystinyl-aminopeptidase activity increased significantly in testes and liver and decreased in the adrenal glands of olive oil-fed mice. There was a significant decrease in membranebound cystinyl-aminopeptidase activity in the adrenal glands of olive oil-fed mice. These findings show that a diet supplemented with olive oil modifies certain aminopeptidase activities in specific tissues. The results may reflect functional modifications in susceptible endogenous substrates.