Pregnant rats treated with a high-fat/prooxidant Western diet with ANG II and TNF-α are resistant to elevations in blood pressure and renal oxidative stress

Abstract

Oxidative stress and inflammation are risk factors for hypertension in pregnancy. Here, we examined the 24-h mean arterial pressure (MAP) via telemetry and the nitric oxide (NO) and redox systems in the kidney cortex, medulla, and aorta of virgin and pregnant rats treated with a high-fat/prooxidant Western diet (HFD), ANG II, and TNF-α. Female Sprague-Dawley rats were given a normal diet (ND) or a HFD for 8 wk before mating. Day 6 of pregnancy and age-matched virgins were implanted with minipumps infusing saline or ANG II (150 ng·kg(-1)·min(-1)) + TNF-α (75 ng/day) for 14 days. Groups consisted of Virgin + ND + Saline (V+ND) (n = 7), Virgin + HFD +ANG II and TNF-α (V+HFD) (n = 7), Pregnant + ND + Saline (P+ND) (n = 6), and Pregnant + HFD + ANG II and TNF-α (P+HFD) (n = 8). After day 6 of minipump implantation, V+HFD rats displayed an increase in MAP on days 7, 8, and 10-15 vs. V+ND rats. P+HFD rats, after day 6 of minipump implantation, showed an increase in MAP only on day 7 vs. P+ND rats. P+HFD rats had a normal fall in 24-h MAP, hematocrit, plasma protein concentration, and osmolality at late pregnancy. No change in kidney cortex, medulla, or aortic oxidative stress in P+HFD rats. P+HFD rats displayed a decrease in nNOSβ abundance, but no change in kidney cortex NOx content vs. P+ND rats. Pregnant rats subjected to a chronic HFD and prooxidant and proinflammatory insults have a blunted increase in 24-h MAP and renal oxidative stress. Our data suggest renal NO bioavailability is not altered in pregnant rats treated with a HFD, ANG II, and TNF-α.

Keywords: ANG II; Western diet; nitric oxide; oxidative stress; tumor necrosis factor-α.

Fig. 1.

Experimental setup. Four groups of rats completed the experimental timeline displayed above. The four groups consisted of Virgin + Normal Diet (ND) + saline (V+ND) (n = 7), Virgin + High-Fat/Western diet (HFD) + ANG II and TNF-α (V+HFD) (n = 7), Pregnant + ND + Saline (P+ND) (n = 5), and Pregnant + HFD + ANG II and TNF-α rats (P+HFD) (n = 8).

Fig. 2.

A: Body weights (g) over time in virgin (V) and pregnant (P) rats given a normal diet and saline mini-pump infusion (V+ND and P+ND, respectively) or a high-fat/Western diet, ANG II, and TNF-α mini-pump infusion (V+HFD and P+HFD). □ denotes: V+ND (n = 7), ■ denotes V+HFD (n = 7), open triangles denote P+ND (n = 5), and ▲ denotes P+HFD (n = 8). *Significant difference in the rate of rise of body weight (BW) over the first 15 days on the diet, between normal diet (ND) and high-fat diet (HFD) groups in both virgins and pregnant rats. **Significant difference in the rate of rise of BW between virgin and pregnant groups with and without treatment, between experimental days 10 and 20. *P < 0.05 and **P < 0.05, two-way ANOVA with multiple-comparison test with Bonferroni adjustments. B: daily food intake (in kilocalories) over time in virgin (V) and pregnant (P) rats given a normal diet and saline minipump infusion (V+ND and P+ND, respectively) or a high-fat/Western diet, ANG II, and TNF-α minipump infusion (V+HFD and P+HFD, respectively).White bars denote V+ND rats (n = 7); gray bars denote V+HFD rats (n = 7), white-hatched bars denote P+ND (n = 5), and gray-hatched bars denote P+HFD rats (n = 8). *P < 0.05 vs. V+ND, †P < 0.05 vs. P+ND, ‡P < 0.05 vs. V+HFD, using two-way ANOVA with multiple-comparison test with Bonferroni adjustments.

Fig. 3.

Baseline 24 h. Mean arterial pressure (MAP), before mating, in virgin (V) and pregnant (P) rats given a normal diet [V+ND (n = 7) and P+ND (n = 5); white and white hatched histogram, respectively] or a high-fat/Western diet [V+HFD (n = 7) and P+HFD (n = 8): gray and gray-hatched histogram, respectively].

Fig. 4.

MAP averaged over 24 h, shown as adjusted least squares means from three-way analysis of covariance, at baseline and experimental days 2–19 in virgin rats (A) and pregnant rats (B) given a normal diet and saline minipump infusion (ND) or a high-fat/Western diet, ANG II, and TNF-α minipump infusion (HFD) rats for 14 days. *Significant difference between ND (open symbol) and HFD (closed symbol), virgin (square) and pregnant (triangle) rats by independent t-test on each day. C: table gives the adjusted mean difference in MAP and the P value, for days 7–19. The groups are V+ND (n = 7), V+HFD (n = 7), P+ND (n = 5), and P+HFD (n = 8).

Fig. 5.

Change in MAP vs. baseline averaged in virgin rats (A) and pregnant rats (B) given a normal diet and saline minipump infusion (ND) or a high-fat/Western diet, ANG II, and TNF-α minipump infusion (HFD) rats for 14 days. *Significant difference between ND (open symbol) and HFD (closed symbol), virgin (square) and pregnant (triangle) rats by independent t-test on each day. The groups are V+ND (n = 7), V+HFD (n = 7), P+ND (n = 5), and P+HFD (n = 8).

Fig. 6.

Representative blots and densitometric analysis for eNOS, nNOSα, and nNOSβ in the kidney cortex (A), kidney medulla (B), and the aorta (C) of virgin and pregnant rats given a normal diet and saline minipump infusion (V+ND or P+ND) or a high-fat/Western diet, ANG II, and TNF-α minipump (V+HFD or P+HFD) infusion for 14 days. Densitometry analysis was quantified as integrated optical density (IOD) normalized to Ponceau (PON) staining and the positive control (POS) for each protein of interest. White bars represent V+ND rats (n = 7), gray bars represent V+HFD rats (n = 7), white hatched bars represents P+ND (n = 5), and gray hatched bars represent P+HFD rats (n = 8).*P < 0.05 vs. V+ND, †P < 0.05 vs. P+ND, ‡P < 0.05 vs. V+HFD; Two-way ANOVA with multiple comparison test with Bonferroni adjustments.

Fig. 7.

Representative blots and densitometric analysis for extracellular SOD (ecSOD), MnSOD, and Cu/Zn SOD in the kidney cortex (A), kidney medulla (B), and the aorta (C) of virgin (V) and pregnant (P) rats given a normal diet and saline minipump infusion (V+ND or P+ND) or a high-fat/Western diet, ANG II, and TNF-α minipump infusion (V+HFD or P+HFD) for 14 days. Densitometry analysis was quantified as integrated optical density (IOD) normalized to Ponceau (PON) staining and the positive control (POS) for each protein of interest in each tissue. The tissue total antioxidant capacity was quantified and expressed as micromole of Trolox per milligram of protein for each tissue. White bars represent V+ND rats (n = 7), gray bars represent V+HFD rats (n = 7), white hatched bars represent P+ND (n = 5), and gray hatched bars represent P+HFD rats (n = 8). †P < 0.05 vs. P+ND, ‡P < 0.05 vs.V+HFD. Two-way ANOVA with multiple-comparison test with Bonferroni adjustments.

Fig. 8.

Representative blots and densitometric analysis for P22phox and nitrotyrosine in the kidney cortex (A), kidney medulla (B), and the aorta (C) of virgin and pregnant rats given a normal diet and saline mini-pump infusion (V+ND or P+ND) or a high fat/western diet, ANGII, and TNFα mini-pump infusion (V+HFD or P+HFD) for 14 days. Densitometry analysis was quantified as integrated optical density (IOD) normalized to ponceau (PON) staining and the positive control (POS) for each protein of interest in each tissue. White histograms represents V+ND rats (n = 7), grey histograms represent V+HFD rats (n = 7), white hatched histograms represents P+ND (n = 5), and grey hatched histograms represent P+HFD rats (n = 8). *P < 0.05 vs. V+ND, ‡P < 0.05 vs.V+HFD; Two-way ANOVA with multiple-comparison test with Bonferroni adjustments.