Paradoxical Effect of Nonalcoholic Red Wine Polyphenol Extract, Provinols™, in the Regulation of Cyclooxygenases in Vessels from Zucker Fatty Rats (fa/ fa)

Abstract

The aim of this work was to study the vascular effects of dietary supplementation of a nonalcoholic red wine polyphenol extract, Provinols, in Zucker fatty (ZF) obese rats. ZF or lean rats received diet supplemented or not with Provinols for 8 weeks. Vasoconstriction in response to phenylephrine (Phe) was then assessed in small mesenteric arteries (SMA) and the aorta with emphasis on the contribution of cyclooxygenases (COX). Although no difference in vasoconstriction was observed between ZF and lean rats both in SMA and the aorta, Provinols affected the contribution of COX-derived vasoconstrictor agents. The nonselective COX inhibitor, indomethacin, reduced vasoconstriction in vessels from both groups; however, lower efficacy was observed in Provinols-treated rats. This was associated with a reduction in thromboxane-A2 and 8-isoprostane release. The selective COX-2 inhibitor, NS398, reduced to the same extent vasoconstriction in aortas from ZF and Provinols-treated ZF rats. However, NS398 reduced response to Phe only in SMA from ZF rats. This was associated with a reduction in 8-isoprostane and prostaglandin-E release. Paradoxically, Provinols decreased COX-2 expression in the aorta, while it increased its expression in SMA. We provide here evidence of a subtle and paradoxical regulation of COX pathway by Provinols vessels from obese rats to maintain vascular tone within a physiological range.

Figure 1

Provinols did not affect contractile response to Phe in aortas and SMA from obese ZF rats. Shown are concentration-response curves to phenylephrine (Phe) cumulative concentrations (M) of small mesenteric arteries (SMA, (a)) and rat aortic rings (b) from lean and ZF rats treated or not with Provinols. Values are expressed as mean ± SEM of millinewtons (mN) per mm of vessel length. N = 6 in each group.

Figure 2

Effect of NO inhibition on vasoreactivity in aortas and SMA from obese ZF rats. Shown are concentration-response curves to phenylephrine (Phe) cumulative concentrations (M) in the presence of NO-synthase nonselective inhibitor (L-NAME) of small mesenteric arteries (SMA) (a–c) and rat aortic rings (d–f) from ZF rats treated or not with Provinols. Values are expressed as mean ± SEM of millinewtons (mN) per mm of vessel length. ^∗∗∗P < 0.001 versus ZF rats.

Figure 3

Provinols reduced the involvement of COX-derived vasoconstrictor metabolites in SMA from obese ZF rats. Concentration-response curves to phenylephrine (Phe) cumulative concentrations (M) in the presence of COX-2 inhibitor (NS398) or the nonselective COX inhibitor (indomethacin, INDO) of small mesenteric arteries (SMA) from ZF rats which received or not Provinols. N = 6 in each group. Values are expressed as mean ± SEM of millinewtons (mN) per mm of vessel length. ^∗P < 0.05; ^∗∗P < 0.01; ^∗∗∗P < 0.001 versus ZF rats.

Figure 4

Provinols reduced the involvement of COX-derived vasoconstrictor metabolites in the aorta from obese ZF rats. Concentration-response curves to phenylephrine (Phe) cumulative concentrations (M) in the presence of COX-2 inhibitor (NS398) or the nonselective COX inhibitor (indomethacin, INDO) of aorta rings from ZF rats which received or not Provinols. Values are expressed as mean ± SEM of millinewtons (mN) per mm of vessel length. N = 6 in each group. ^∗∗∗P < 0.001 versus ZF rats.

Figure 5

Provinols reduced COX-derived vasoconstrictor metabolite release in aortas and SMA from obese ZF rats. Concentration of COX derivatives thromboxane A2, prostaglandin E2 (PGE2), 8-isoprostane, and prostacyclin in the supernatants of the rat aorta and SMA from ZF rats treated or not with Provinols and stimulated with Phe (n = 6). The concentration of prostanoids is expressed as pg/mL/mg of dry weight (dw) tissue. ^∗P < 0.05; ^∗∗P < 0.01 versus ZF rats.

Figure 6

Provinols modulated the expression of COX isoforms and NF-κB in vessels from obese ZF rats. Western blots showing the expression of cyclooxygenase- (COX-) 1 (a, b) and COX-2 (c, d) in the aorta and SMA from ZF rats treated or not with Provinols. NF-κB expression in the rat aorta was assessed by confocal imaging (e) and western blot analysis (f). In (c) is shown NF-κB expression in SMA by western blot analysis. Quantification of immunoblots' signal was done by densitometric analysis; β-actin loading control was included. Data are representative of four separate blots, and the densitometry values are expressed in arbitrary units (A.U.) as mean ± SEM. ^∗∗P < 0.01; ^∗∗∗P < 0.001 versus ZF rats.