Mechanisms of the antihypertensive effects of Nigella sativa oil in L-NAME-induced hypertensive rats

Kamsiah Jaarin,Wai Dic Foong,Min Hui Yeoh,Zaman Yusoff Nik Kamarul,Haji Mohd Saad Qodriyah,Abdullah Azman,Japar Sidik Fadhlullah Zuhair,Abdul Hamid Juliana,Yusof Kamisah

doi:10.6061/clinics/2015(11)07

Abstract

OBJECTIVESThis study was conducted to determine whether the blood pressure-lowering effect of Nigella sativa might be mediated by its effects on nitric oxide, angiotensin-converting enzyme, heme oxygenase and oxidative stress markers.METHODS:Twenty-four adult male Sprague-Dawley rats were divided equally into 4 groups. One group served as the control (group 1), whereas the other three groups (groups 2-4) were administered L-NAME (25 mg/kg, intraperitoneally). Groups 3 and 4 were given oral nicardipine daily at a dose of 3 mg/kg and Nigella sativa oil at a dose of 2.5 mg/kg for 8 weeks, respectively, concomitantly with L-NAME administration.RESULTSNigella sativa oil prevented the increase in systolic blood pressure in the L-NAME-treated rats. The blood pressure reduction was associated with a reduction in cardiac lipid peroxidation product, NADPH oxidase, angiotensin-converting enzyme activity and plasma nitric oxide, as well as with an increase in heme oxygenase-1 activity in the heart. The effects of Nigella sativa on blood pressure, lipid peroxidation product, nicotinamide adenine dinucleotide phosphate oxidase and angiotensin-converting enzyme were similar to those of nicardipine. In contrast, L-NAME had opposite effects on lipid peroxidation, angiotensin-converting enzyme and NO.CONCLUSION:The antihypertensive effect of Nigella sativa oil appears to be mediated by a reduction in cardiac oxidative stress and angiotensin-converting enzyme activity, an increase in cardiac heme oxygenase-1 activity and a prevention of plasma nitric oxide loss. Thus, Nigella sativa oil might be beneficial for controlling hypertension.

Highlights

Hypertension is defined as a persistent elevation of systolic blood pressure of 140 mmHg or greater and/or diastolic blood pressure of 90 mmHg or greater
There was no significant difference in cardiac MDA content in the control, L-NAME+ nicardipine and L-NAME+Nigella sativa groups
We demonstrated that the intraperitoneal administration of an nitric oxide (NO) synthase inhibitor (L-NAME) at a dose of 25 mg/kg increased blood pressure in rats

Summary

Introduction

Hypertension is defined as a persistent elevation of systolic blood pressure of 140 mmHg or greater and/or diastolic blood pressure of 90 mmHg or greater. Hypertension is a major risk factor for cardiovascular, cerebrovascular and renal diseases [1]. Oxidative stress is important in the pathogenesis of essential hypertension or in arterial damage related to essential hypertension [2,3]. This was shown by an elevation of lipid peroxidation in hypertensive patients [2]. The increases in oxidative stress will reduce the bioavailability of nitric oxide (NO), a potent vasodilator [3] and this reduction contributes to the development of hypertension.

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