Effect of different high-fat diets on the myocardium stereology and blood pressure in rats

Dietary Effects of Structured Lipids and Phytosteryl Esters on Cardiovascular Function in Spontaneously Hypertensive Rats

This study examined the dietary effects of sesame oil (SO)-based structured lipids (SL) and phytosteryl esters (PE) on cardiovascular function in conscious spontaneously hypertensive rats (SHR) fed high-fat (HF) diets (20% w/w fat). The dietary groups were as follows: normal diet (4.5% w/w fat), SO, SO fortified with PE (SOP), SL, and SL fortified with PE (SLP). Mean arterial blood pressures were similar in all groups, whereas resting heart rates (HR) were higher in all HF-fed groups. The pressor responses to the alpha1-adrenoceptor agonist, phenylephrine (5 microg/kg), were similar in all groups. However, the pressor responses to phenylephrine (10 microg/kg) were diminished in SO- or SL-fed SHR, whereas they were not diminished in SOP- or SLP-fed SHR. The depressor responses elicited by the nitric oxide (NO) donor, sodium nitroprusside (5 and 10 microg/kg), were not diminished in HF-fed rats. Baroreflex-mediated changes in HR were variously decreased in the HF-fed groups, and this decrease tended to be greater in SOP and SLP than in SO and SL groups. The depressor and tachycardic responses elicited by the beta-adrenoceptor agonist, isoproterenol, were equivalent in all groups. The depressor responses elicited by the endothelium-dependent agonist, acetylcholine (0.1 microg/kg), and the hypertension elicited by the NO synthesis inhibitor, NG-nitro-L-arginine methylester (25 micromol/kg), were similar in all groups. These findings demonstrate that (1) HF diets increase resting HR and impair baroreflex function in SHR, whereas they do not obviously affect endothelium-dependent vasodilation, and (2) fortification with PE may be deleterious to cardiovascular function (eg, baroreflex activity) in SHR.

Argan (Argania spinosa) oil lowers blood pressure and improves endothelial dysfunction in spontaneously hypertensive rats

Traditionally hand-pressed argan oil, obtained from Argania spinosa seeds, is eaten raw in south-west Morocco; its rich composition of tocopherols, MUFA and PUFA make a study of its actions on risk factors for CVD, such as hypertension, interesting. The effects of 7 weeks of treatment with argan oil (10ml/kg) on the blood pressure and endothelial function of spontaneously hypertensive rats (SHR) and normotensive Wistar–Kyoto rats were investigated. Systolic blood pressure and heart rate were measured every week by the tail-cuff method and endothelial function was assessed by carbachol (10−8 to 10−4m)-induced relaxations of aortic rings and small mesenteric arteries pre-contracted with phenylephrine. Argan-oil administration reduced the mean blood pressure of SHR after the fifth week of treatment (P<0·05) and increased (P<0·01) the endothelial responses of arteries from SHR. The NO synthase inhibitor, l-N-ω-nitroarginine (3×10−5m) revealed a greater participation of NO in the relaxant effect after the treatment. When cyclooxygenase (COX) was blocked with indomethacin (10−5m), an involvement of COX products in the endothelium-dependent response was characterized. Enzyme immunoassay of thromboxane B2 showed a significant decrease (P<0·05) in the release of thromboxane A2 in both aorta and small mesenteric artery after argan-oil treatment of SHR. Experiments in the presence of the thromboxane A2–prostaglandin H2 receptor antagonist ICI 192, 605 (10−5m) confirmed this result. Results after incubation with the antioxidants superoxide dismutase and catalase suggested that a decreased oxidative stress might contribute to explain the beneficial effects of argan-oil treatment.

Spontaneously hypertensive rats left ventricular cardiomyocyte loss attenuation through different edible oils long-term intake

BACKGROUND

Dietary lipid intake type affecting spontaneously hypertensive rats (SHR) blood pressure (BP). There are no information available whether different edible lipids long-term administration does potentiality alter the usual cardiomyocyte loss in SHR or not.

METHODS

Six groups of 3-month-old male SHR received different edible oils (fish, canola, palm, olive, and soybean oils-1.5 g/kg/day+1 UI of vitamin E per ml) or water (control) by gavage for 13 weeks. Left ventricular cardiomyocyte number (N[cmn]) was analysed through stereology and disector method.

RESULTS

BP showed lower in the experimental groups (30% in the fish oil group, 15% in both canola oil and palm oil groups, 5% in both olive oil and soybean oil groups) when compared to the control group. N[cmn] was greater in the fish oil group and smaller in the control group. N[cmn] was over 130% greater in the fish oil group, and more than 25% greater in the canola, palm, and olive oils groups compared to the control group. N[cmn] showed a negative correlation with BP (R=-0.98, p<0.01).

CONCLUSION

Hypertension nutritional management and subsequent prevention/attenuation of left ventricular cardiomyocyte loss pointed out a novel therapeutic strategy to be seriously considered in the long-term hypertension treatment. The goal is to postpone the consequences of cardiomyocyte number decrease and heart failure in hypertension.

Aorta wall quantitative alterations due to different long-term high-fat diet in rats

Twenty Wistar male rats, with ages varying from 21 days to 12 months, were fed with diets supplemented by soybean oil (S group), canola oil (CA group), lard and egg yolk (LE group), and canola plus lard and egg yolk (CA+LE group). The LE group presented the highest heart mass/body mass ratio and the highest blood pressure as well. The aortic structure suffered a number of alterations, from CA rats group (minor alterations) to LE and CA+LE rats group (major alterations). The CA group showed the smallest aorta thickness. No significant differences among groups were found concerning the number of aortic lamellae and the density of tunica media smooth muscle nuclei. Surface density of the aortic lamellae was greater in the CA group and smaller in the LE group. These results suggest that the dietary intake of canola oil could attenuate the aorta structure aging process with a favorable BP maintenance.

Heart and blood pressure adaptations in Wistar rats fed with different high-fat diets for 18 months

OBJECTIVE

We investigated the effect of long-term administration of four different high-fat diets on systolic blood pressure (SBP), body and heart biometry, and left ventricular myocyte nuclei number (N[lvm]).

METHODS

Twenty-four Wistar rats were assigned to one of four groups from weaning to age 18 mo. The rats were fed experimental diets containing soybean oil (S group), canola oil (CA group), lard and egg yolk (LE group), and canola oil plus lard and egg yolk (CA + LE group). N(lvm) was measured with the disector method in isotropic uniform random sections of the left ventricular myocardium.

RESULTS

There were no significant differences across experimental groups in morphometric indices. SBP was higher in the LE group at all ages and lower in the 18-mo CA group. The myocardium structure analysis separated the animals in three major categories: the CA and LE groups as the extreme and the S and CA + LE groups as the intermediary. In the LE group the myocardium presented more important structural changes: cardiac myocytes were enlarged and surrounded with thick collagen bundles, and some regions exhibited myocardial necrosis.

CONCLUSION

Long-term intake of the CA diet was more efficient in maintaining normal N(lvm) and SBP than the S and LE diets. The CA + LE diet resulted in balanced levels of SBP and N(lvm) in rats, suggesting that canola oil reduces cardiovascular injury caused by intake of lard and egg yolk.