In vivo angiotensin I-converting enzyme inhibition by long-term intake of antihypertensive lactoferrin hydrolysate in spontaneously hypertensive rats

We evaluated the effect of the long-term intake of a bovine lactoferrin hydrolysate enriched in low molecular weight peptides (LFH < 3 kDa) on the progression of hypertension in spontaneously hypertensive rats and its in vivo mechanism of action. Male spontaneously hypertensive rats received tap water (negative control), captopril (positive control, 76 mg/kg/day), LFH < 3 kDa (285 mg/kg/day), or LFH < 3 kDa (782 mg/kg/day). Twice a week, systolic blood pressure, body weight and liquid intake were measured. Blood components of the renin-angiotensin system were determined. The systolic blood pressure of spontaneously hypertensive rats receiving water increased along the 24-day follow-up period, while systolic blood pressure around or slightly below the baseline was maintained in both LFH < 3 kDa treated groups. The antihypertensive effects appeared earlier in the high-dose than in the low-dose group. There were no differences in body weight gain between the two groups but liquid intake increased in rats treated with high-dose LFH < 3 kDa. There were reductions of circulating angiotensin I-converting enzyme activity, angiotensin 11 and aldosterone levels, as well as a compensatory increase of renin activity after LFH < 3 kDa intake. Our results support angiotensin I-converting enzyme inhibition as an in vivo mechanism for the antihypertensive effect of long-term oral administration of LFH < 3 kDa to spontaneously hypertensive rats and its potential application as a nutraceutical approach for hypertension treatment. (C) 2013 Elsevier Ltd. All rights reserved.