Vascular nitrosative stress in hypertension induced by fetal undernutrition in rats

Fetal undernutrition predisposes to hypertension development. Since nitric oxide (NO) is a key factor in blood pressure control, we aimed to investigate the role of NO alterations in hypertension induced by fetal undernutrition in rats. Male and female offspring from dams exposed to undernutrition during the second half of gestation (MUN) were studied at 21 days (normotensive) and 6 months of age (hypertension developed only in males). In aorta, we analyzed total and phosphorylated endothelial NO synthase (eNOS, p-eNOS), 3-nitrotyrosine (3-NT), and Nrf2 (Western blot). In plasma we assessed l-arginine, asymmetric and symmetric dimethylarginine (ADMA, SDMA; LC–MS/MS), nitrates (NOx, Griess reaction), carbonyl groups, and lipid peroxidation (spectrophotometry). In iliac arteries, we studied superoxide anion production (DHE staining, confocal microscopy) and vasodilatation to acetylcholine (isometric tension). Twenty-one-day-old MUN offspring did not show alterations in vascular e-NOS or 3NT expression, plasma l-Arg/ADMA ratio, or NOx. Compared to control group, 6-month-old MUN rats showed increased aortic expression of p-eNOS/eNOS and 3-NT, being Nrf2 expression lower, elevated plasma l-arginine/ADMA, NOx and carbonyl levels, increased iliac artery DHE staining and reduced acetylcholine-mediated relaxations. These alterations in MUN rats were sex-dependent, affecting males. However, females showed some signs of endothelial dysfunction. We conclude that increased NO production in the context of a pro-oxidative environment, leads to vascular nitrosative damage and dysfunction, which can participate in hypertension development in MUN males. Females show a better adaptation, but signs of endothelial dysfunction, which can explain hypertension in ageingOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Natur

Long term effects of fetal undernutrition on rat heart. Role of hypertension and oxidative stress

<div><p>Background and aims</p><p>Fetal undernutrition is a risk factor for heart disease in both genders, despite the protection of women against hypertension development. Using a rat model of maternal undernutrition (MUN) we aimed to assess possible sex differences in the development of cardiac alterations and the implication of hypertension and cardiac oxidative stress.</p><p>Methods</p><p>Male and female offspring from rats fed <i>ad libitum</i> (control) or with 50% of the normal daily intake during the second half of gestation (MUN) were used. Heart weight/body weight ratio (HW/BW), hemodynamic parameters (anaesthetized rats) and plasma brain natriuretic peptide (BNP, ELISA) were assessed in 21-day, 6-month and 22-month old rats. Plasma testosterone (ELISA) and cardiac protein expression of enzymes related to reactive oxygen species synthesis (p22^phox, xanthine-oxidase) and degradation (catalase, Cu/Zn-SOD, Mn-SOD, Ec-SOD) were evaluated in 21-day and 6-month old rats (Western Blot). Heart structure and function was studied at the age of 22 months (echocardiography).</p><p>Results</p><p>At the age of 21 days MUN males exhibited significantly larger HW/BW and cardiac p22^phox expression while females had reduced p22^phox expression, compared to their respective sex-matched controls. At the age of 6-months, MUN males showed significantly larger blood pressure and cardiac xanthine-oxidase expression; MUN females were normotensive and had a lower cardiac expression of antioxidant enzymes, compared to their respective sex-matched controls. At the age of 22 months, both MUN males and females showed larger HW/BW and left ventricular mass and lower ejection fraction compared to sex-matched controls; only MUN males exhibited hypertension and a larger plasma BNP compared to aged male controls.</p><p>Conclusions</p><p>1) During perinatal life females exposed to fetal undernutrition are protected from cardiac alterations, but in ageing they exhibit ventricular hypertrophy and functional loss, like MUN males; 2) cardiac oxidative stress might be implicated in the observed heart alterations in both sexes and 3) the severity of cardiac damage might be greater in males due to hypertension.</p></div

Echocardiographic parameters in 22-month old rats.

<p>(A) male and (B) female offspring from rats exposed to maternal undernutrition during pregnancy (MUN) and rats fed <i>ad libitum</i> (Control). Interventricular septum at diastole (IVSd), posterior wall thickness at diastole (PWd), left ventricular internal diameter at diastole (LVIDd) and at systole (LVIDs), left ventricular mass (LVM) and left ventricular ejection fraction (LVEF). In parenthesis it is shown the number of rats; *p<0.05 compared to sex-matched control rats.</p

Plasma brain natriuretic peptide (BNP) levels in MUN and control rats of different ages.

<p>(A) maleand (B) female offspring from rats exposed to maternal undernutrition during pregnancy (MUN) and rats fed <i>ad libitum</i> (Control). In parenthesis it is shown the number of rats; *p<0.05 compared to sex-matched control rats.</p

Blood pressure measurements in anesthetized MUN and control rats at different age points.

<p>Intra-arterial systolic, diastolic and mean blood pressure (SBP, DBP, MBP) and pulse pressure (PP) in rats under Medetomidine/Ketamine anesthesia. (A) male and (B) female offspring from rats exposed to maternal undernutrition during pregnancy (MUN) and rats fed <i>ad libitum</i> (Control). In parenthesis the number or rats used at each age point; *p<0.05 compared to sex and age-matched control rats.</p

Protein expression of SOD isoforms and catalase in cardiac tissue from 6-month old rats.

<p>Superoxide dismutase (SOD) isoforms, Cu/Zn-SOD, Mn-SOD and extracellular SOD (EC-SOD) and catalase. (A) maleand (B) female offspring from rats exposed to maternal undernutrition during pregnancy (MUN) and rats fed <i>ad libitum</i> (Control). Diagram bars show the results of densitometric analysis, relativized to GADPH expression. In parenthesis it is shown the number or rats; *p<0.05 compared to sex-matched control rats.</p

Heart rate (HR) measured in anesthetized MUN and control rats at different age points.

<p>HR was measured under Medetomidine/Ketamine anesthesia at all age points. In 22-month old rats HR was also measured under Diazepam/Ketamine anesthesia. (A) male and (B) female offspring from rats exposed to maternal undernutrition during pregnancy (MUN) and rats fed <i>ad libitum</i> (Control). In parenthesis the number or rats used at each age point; *p<0.05 compared to sex and age-matched control rats; #p<0.05 compared to Medetomidine/Ketamine anesthesia.</p

Plasma testosterone levels in 21-day and 6-month old rats.

<p>(A) male and (B) female offspring from rats exposed to maternal undernutrition during pregnancy (MUN) and rats fed <i>ad libitum</i> (Control). In parenthesis it is shown the number of rats.</p

Protein expression of p22^phox and xanthine oxidase (XO) in cardiac tissue from 21-day old rats.

<p>(A) male and (B) female offspring from rats exposed to maternal undernutrition during pregnancy (MUN) and rats fed <i>ad libitum</i> (Control). Diagram bars show the results of densitometric analysis, relativized to GADPH expression. In parenthesis it is shown the number or rats; *p<0.05 compared to sex-matched control rats.</p