Pomace olive oil improves endothelial function in spontaneously hypertensive rats by increasing endothelial nitric oxide synthase expression.
BACKGROUND
The effect of dietary pomace olive oil, which has the same concentration of oleic acid but a higher proportion of oleanolic acid (OA) than olive oil, was examined on animal models of hypertension for the first time.


METHODS
During 12 weeks, Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) were fed with either a control 2% corn oil diet (BD), or high-fat diets containing 15% of refined olive oil (OL), pomace olive oil (POM), or pomace olive oil supplemented in OA (up to 800 ppm) (POMO). Then, vascular reactivity and endothelial nitric oxide (NO) synthase (eNOS) expression were studied in aortic rings. Plasma nitrite + nitrate levels were also determined.


RESULTS
Diets had no effects on blood pressure (BP). In contrast to the BD and OL dietary groups, POM intake improved relaxation evoked by acetylcholine in SHR aorta. The POMO intake increased vasodilatation to acetylcholine and attenuated phenylephrine-induced contractions in both strains of rats associated with a major NO participation revealed by inhibition of NOS. The enhanced relaxation shown in POM and POMO SHR aorta was attributed to an increased eNOS protein expression. Plasma nitrite levels were also increased in these groups. Although olive and pomace oils used in diets contained similar fatty acid composition, beneficial effects on endothelial function were absent in the OL group. Therefore, these effects must be associated with some minor components from pomace olive oil such as OA.


CONCLUSIONS
Chronic intake of diets rich in pomace olive oil improves endothelial dysfunction in SHR aorta by mechanisms associated with enhanced eNOS expression. Important evidence is provided regarding the effects of pomace olive oil and OA on endothelial function in hypertensive animals.
Rodriguez-Rodriguez
Rosalia
R
Instituto de la Grasa (CSIC), Seville, Spain.
Herrera
Maria Dolores
MD
de Sotomayor
Maria Alvarez
MA
Ruiz-Gutierrez
Valentina
V
D000818:Animals; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000502:physiology; D006973:Hypertension / Q000517:prevention & control*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D009828:Oleanolic Acid / Q000627:therapeutic use*; D000069463:Olive Oil; D010938:Plant Oils / Q000008:administration & dosage* / Q000737:chemistry; D011453:Prostaglandins / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY
D000069463:Olive Oil; D010938:Plant Oils; D011453:Prostaglandins; D009569:Nitric Oxide; D009828:Oleanolic Acid; D052250:Nitric Oxide Synthase Type III