Cardiovascular beneficial effects of a milk casein hydrolysate after long-term intake in SHR

Abstract

In recent years, there has been considerable interest in using functional foods to treat hypertension, especially for patients with mild high blood pressure that does not warrant the prescription of anti hypertensive drugs [1]. We have previously reported that certain peptides were able to decrease blood pressure in spontaneously hypertensive rats (SHR) after single oral administration [2]. The aim of this study was to evaluate the effect of the long term intake of a milk casein hydrolysate, containing antihypertensive peptides, on the development of hypertension. Methods: 12 weeks old SHR were randomly divided in two groups that received tap water (C) or a daily dose of 800 mg/kg body weight of hydrolysate (H) during 6 weeks. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured weekly by the tail cuff method. At the end of treatment, left ventricle was isolated and weighed in order to evaluate left ventricular hypertrophy (LVH). Cardiac fibrosis was measured in histological sections stained with Sirius red. Vascular reactivity was assessed checking responses to acetylcholine (ACh) and sodium nitroprusside (SNP) in aortic rings and eNOS expression were studied by western blotting in aorta homogenates. Results: The table below shows SBP and DBP values, they were similar in both groups at the beginning and rose progressively during the study. However, it is worth to note that the hypertension development was attenuated by administration of the hydrolysate. A significant decreased of LVH was observed in treated animals (C, 3.04±0.06 mg/g; H, 2.90±0.04 mg/g, p<0.05) which was accompanied with an important reduction in interstitial fibrosis. Treatment with the hydrolysate improved ACh relaxations (C, 41±5%; H, 54±6%, p<0.05) without changes in SNP responses. The western blot analysis showed an increase in eNOS expression in aorta that could explain the improvement of endothelial dysfunction and the attenuation of hypertension development. In conclusion, the milk casein hydrolysate could be used as a functional food ingredient with antihypertensive activity.