Uniqueness of dietary olive oil in stimulating aortic prostacyclin production in post-weanling rats

Groups of weanling Sprague-Dawley rats developed from conception through gestation, and weanling periods on a formulated diet fed to the dams were continued on the same diet until sacrificed at 30 days of age. The diet groups consisted of control (5% corn oil, w/w) and experimental (15%, w/w) olive, safflower (hi-oleic and hi-linoleic), soy oil, and lard. The object of the study was to identify the effect of high and low fat content and differing proportions of polyunsaturated:saturated (P:S) and mono:polyunsaturated (M:P) fatty acids on arachidonate stimulated aortic prostacyclin (PGI2) production (measured as 6-keto-PGF1 alpha). Neither the amounts of dietary fat or wide ranging P:S or M:P fatty acid ratio levels (P:S or M:P) affected PGI2 production. PGI2 production was, however, markedly enhanced (2x) in aortic segments from rats raised on diets containing olive oil. The unique stimulation of aortic PGI2 production by the olive oil diet suggests an effect of the extraordinarily high M:P fatty acid ratio or, alternatively, of a still-to-be identified substance(s) in this ancient food.