Effect and Mechanism of Rosa roxburghii Fruit Polyphenols on Hypertension Induced by NG-Nitro-L-Arginine Methyl Ester in Mice

Abstract

Objective: To investigate the effect and possible mechanism of Rosa roxburghii fruit polyphenols (RRP) on hypertension induced by NG-nitro-L-arginine methyl ester (L-NAME) in mice. Methods: RRP with a purity of 68% was prepared in the laboratory. L-NAME was used to induce a mouse model of hypertension, and the mice were divided into four groups: model, positive control (captopril), low-dose RRP, and high-dose RRP. All mice were killed and dissected for measurement of organ indexes. Mice not treated with L-NAME served as a control group. The serum was collected to determine the levels of nitric oxide (NO), endothelin-1 (ET-1), renin, angiotensin II (Ang II), aldosterone (ALD), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α). The levels of oxidative stress markers including malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were assayed in kidney and liver tissues, and heart and kidney tissues were stained with hematoxylin and eosin (HE) for pathological observation. Results: Compared with the blank group, the model group showed a significant increase in blood pressure; serum NO concentration significantly decreased (P < 0.05), serum IL-6 and TNF-α levels significantly increased (P < 0.05), and serum ET-1, renin, Ang II, and ALD levels significantly increased (P < 0.05). MDA levels in kidney and liver tissues significantly increased (P < 0.05), and SOD and GSH-Px activities significantly decreased (P < 0.05). Compared with the model group, blood pressure significantly increased in the positive control group and the low- and high-dose RRP groups (P < 0.05). Serum NO levels significantly increased (P < 0.05), and serum IL-6, TNF-α, ET-1, renin, Ang II, and ALD levels significantly decreased (P < 0.05). MDA levels in kidney and liver tissues significantly declined (P < 0.05), and GSH-Px activity significantly increased (P < 0.05). Conclusion: RRP has an obvious hypotensive effect, possibly by increasing NO bioavailability, improving endothelial cell dysfunction, inhibiting the over-activation of the renin angiotensin aldosterone system, and reducing inflammation and oxidative stress.

Keywords

• rosa roxburghii fruit polyphenols; hypertension; endothelial function; renin angiotensin aldosterone system; inflammation; oxidative stress