Inhibition of
nitric oxide synthesis with N ( ω )-nitro-
L-arginine methyl ester (
L-NAME) induces marked
hypertension and oxidative stress.
Curcumin (CUR) has been shown strong
antioxidant property.
Tetrahydrocurcumin (THU), a major metabolite of CUR, possesses several pharmacological effects similar to CUR; however, it is less studied than CUR. We investigated whether CUR and THU could prevent vascular dysfunction and inhibit development of
hypertension in
L-NAME-treated rats. Male Sprague-Dawley rats were administered with
L-NAME (50 mg/kg/day) in
drinking water for 3 weeks. CUR or THU (50 and 100 mg/kg/day) was fed to animals simultaneously with
L-NAME.
L-NAME administration induced increased arterial blood pressure and elevated peripheral vascular resistance accompanied with impaired vascular responses to
angiotensin II and
acetylcholine. CUR and THU significantly suppressed the blood pressure elevation, decreased vascular resistance, and restored vascular responsiveness. The improvement of vascular dysfunction was associated with reinstating the marked suppression of eNOS
protein expression in the aortic tissue and plasma
nitrate/
nitrite. Moreover, CUR and THU reduced vascular
superoxide production, decreased oxidative stress, and increased the previously depressed blood
glutathione (GSH) and the redox ratios of GSH in
L-NAME hypertensive rats. The
antihypertensive and some
antioxidant effects of THU are apparently more potent than those of CUR. This study suggests that CUR and THU prevented the development of vascular dysfunction induced by
L-NAME and that the effects are associated with alleviation of oxidative stress.