Antihypertensive and Renoprotective Effects of Dietary Flaxseed and its Mechanism of Action in Deoxycorticosterone Acetate-Salt Hypertensive Rats

Abstract

Background/Aims: Flaxseed contains alpha-linolenic acid (ALA), lignans, and dietary fiber, and its intake lowers blood pressure in hypertensive patients. Here, we examined the effects of flaxseed powder, which includes all flaxseed components, flaxseed oil, composed mainly of ALA, flaxseed lignan, and flaxseed fiber, on hypertension and renal damage induced by deoxycorticosterone acetate (DOCA)-salt. Then, we investigated the mechanisms of action associated with the effects of flaxseed. Methods: Flaxseed powder, oil, lignan, or fiber was administered to DOCA-salt rats. Systolic blood pressure (SBP), urinary protein excretion, renal angiotensin converting enzyme (ACE) activity, sympathetic nerve activity, and gene expression of inflammatory mediators in the kidney and hypothalamus were measured. Results: Flaxseed powder and oil reduced the increases in SBP and urinary protein excretion induced by DOCA-salt treatment, whereas lignan and fiber had no effects. Flaxseed oil suppressed the increase in renal ACE activity, sympathetic nerve activity, and gene expression of renal and hypothalamic inflammatory mediators. Conclusion: Flaxseed has antihypertensive and renoprotective effects in DOCA-salt rats. These effects are likely principally exerted by ALA. Furthermore, the suppression of renal ACE activity, sympathetic nerve activity, and inflammation is partly involved in the effects of flaxseed.