Enalapril and losartan restored blood pressure and vascular reactivity in intrauterine undernourished rats

Pharmacologic and endotoxic reprogramming of renal vasodilatory, inflammatory, and apoptotic blemishes in weaning preeclamptic rats

Preeclampsia (PE) and peripartum sepsis are two complications of pregnancy and are often associated with disturbed renal function due possibly to dysregulated renin angiotensin system. Here we evaluated hemodynamic and renal consequences of separate and combined PE and sepsis insults in weaning mothers and tested whether this interaction is influenced by prenatally-administered losartan (AT1-receptor blocker) or pioglitazone (PPARγ agonist). The PE-rises in blood pressure and proteinuria induced by gestational nitric oxide synthase inhibition (L-NAME, 50 mg/kg/day for 7 days) were attenuated after simultaneous treatment with losartan or pioglitazone. These drugs further improved glomerular and tubular structural defects and impaired vasodilatory responses evoked by adenosinergic (N-ethylcarboxamidoadenosine) or cholinergic (acetylcholine) receptor activation in perfused kidneys of weaning dams. Likewise, treatment of weaning PE dams with a single 4-h dosing of lipopolysaccharides (LPS, 5 mg/kg) weakened renal structural damage, enhanced renal vasodilations and accentuated the upregulated vasodilatory response set off by losartan or pioglitazone. Molecularly, the favorable effect of pharmacologic or endotoxic intervention was coupled with dampened tubular and glomerular expressions of inflammatory (toll-like receptor 4) and apoptotic signals (caspase-3). Our data unveil beneficial and possibly intensified conditioning effect for endotoxemia when combined with losartan or pioglitazone against preeclamptic renovascular dysfunction and inflammation.

Cardiovascular Health Starts in the Womb

Hypertension has largely been viewed as a disorder of adulthood. Historically, blood pressure (BP) was not routinely measured in children because hypertension was considered uncommon in childhood. It was not until the 1970s that it was apparent that in childhood BP levels were normally lower compared with those in adults, were related to age and growth, and that abnormal BP in children needed different definitions. Based on the distribution of BP levels in available child cohorts, the 95th percentile of BP levels became the definition of hypertension in children and adolescents-an epidemiological definition. Subsequent clinical and epidemiological research identified associated risk factors in childhood that linked abnormal BP in youth with hypertension in adulthood. In the 1980s, the Barker hypothesis, based on observations that low birth weight could be linked to cardiovascular disease in adulthood, promoted further research spanning epidemiological, clinical, and basic science on the childhood origins of hypertension. This review focuses on recent findings from both longitudinal maternal-child cohorts and experimental models that examine both maternal and offspring conditions associated with risks of subsequent cardiovascular disease.

Disruption of Atrial Rhythmicity by the Air Pollutant 1,2-Naphthoquinone: Role of Beta-Adrenergic and Sensory Receptors

The combustion of fossil fuels contributes to air pollution (AP), which was linked to about 8.79 million global deaths in 2018, mainly due to respiratory and cardiovascular-related effects. Among these, particulate air pollution (PM2.5) stands out as a major risk factor for heart health, especially during vulnerable phases. Our prior study showed that premature exposure to 1,2-naphthoquinone (1,2-NQ), a chemical found in diesel exhaust particles (DEP), exacerbated asthma in adulthood. Moreover, increased concentration of 1,2-NQ contributed to airway inflammation triggered by PM2.5, employing neurogenic pathways related to the up-regulation of transient receptor potential vanilloid 1 (TRPV1). However, the potential impact of early-life exposure to 1,2-naphthoquinone (1,2-NQ) on atrial fibrillation (AF) has not yet been investigated. This study aims to investigate how inhaling 1,2-NQ in early life affects the autonomic adrenergic system and the role played by TRPV1 in these heart disturbances. C57Bl/6 neonate male mice were exposed to 1,2-NQ (100 nM) or its vehicle at 6, 8, and 10 days of life. Early exposure to 1,2-NQ impairs adrenergic responses in the right atria without markedly affecting cholinergic responses. ECG analysis revealed altered rhythmicity in young mice, suggesting increased sympathetic nervous system activity. Furthermore, 1,2-NQ affected β1-adrenergic receptor agonist-mediated positive chronotropism, which was prevented by metoprolol, a β1 receptor blocker. Capsazepine, a TRPV1 blocker but not a TRPC5 blocker, reversed 1,2-NQ-induced cardiac changes. In conclusion, neonate mice exposure to AP 1,2-NQ results in an elevated risk of developing cardiac adrenergic dysfunction, potentially leading to atrial arrhythmia at a young age.

Protein restriction during peripubertal period impairs endothelial aortic function in adult male Wistar rats

Protein restriction during early phases of body development, such as intrauterine life can favor the development of vascular disorders. However, it is not known if peripubertal protein restriction can favor vascular dysfunction in adulthood. The present study aimed to evaluated whether a protein restriction diet during peripubertal period favors endothelial dysfunction in adulthood. Male Wistar rats from postnatal day (PND) 30 until 60 received a diet with either 23% protein (CTR group) or with 4% protein (LP group). At PND 120, the thoracic aorta reactivity to phenylephrine, acetylcholine, and sodium nitroprusside was evaluated in the presence or absence of: endothelium, indomethacin, apocynin and tempol. The maximum response (Rmax) and pD2 (-log of the concentration of the drug that causes 50% of the Rmax) were calculated. The lipid peroxidation and catalase activity were also evaluated in the aorta. The data were analyzed by ANOVA (one or two-ways and Tukey's) or independent t-test; the results were expressed as mean ± S.E.M., p < 0.05. The Rmax to phenylephrine in aortic rings with endothelium were increased in LP rats when compared with the Rmax in CTR rats. Apocynin and tempol reduced Rmax to phenylephrine in LP aortic rings but not in CTR. The aortic response to the vasodilators was similar between the groups. Aortic catalase activity was lower and lipid peroxidation was greater in LP compared to CTR rats. Therefore, protein restriction during the peripubertal period causes endothelial dysfunction in adulthood through a mechanism related to oxidative stress.

Post-weaning protein malnutrition induces myocardial dysfunction associated with oxidative stress and altered calcium handling proteins in adult rats

Hypercaloric low-protein diet may lead to a state of malnutrition found in the low-income population of Northeastern Brazil. Although malnutrition during critical periods in the early life is associated with cardiovascular diseases in adulthood, the mechanisms of cardiac dysfunction are still unclear. Here we studied the effects of post-weaning malnutrition due to low protein intake induced by a regional basic diet on the cardiac contractility of young adult rats. In vivo arterial hemodynamic and in vitro myocardial contractility were evaluated in 3-month-old rats. Additionally, protein content of the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA), total phospholamban (PLB) and phosphorylated at serine 16 (p-Ser(16)-PLB), α2-subunit of the Na(+)/K(+)-ATPase (α2-NKA), and Na(+)/Ca(2+) exchanger (NXC) and in situ production of superoxide anion (O2(-)) were measured in the heart. Blood pressure and heart rate increased in the post-weaning malnourished (PWM) rats. Moreover, malnutrition decreased twitch force and inotropic responses of the isolated cardiac muscle. Protein expression of SERCA, PLB/SERCA, and p-Ser(16)-PLB/PLB ratios and α2-NKA were decreased without changing NCX. The contraction dependent on transsarcolemmal calcium influx was unchanged but responsiveness to Ca(2+) and tetanic peak contractions were impaired in the PWM group. Myocardial O2(-) production was significantly increased by PWM. Our data demonstrated that this hypercaloric low-protein diet in rats is associated with myocardial dysfunction, altered expression of major calcium handling proteins, and increased local oxidative stress. These findings reinforce the attention needed for pediatric care, since chronic malnutrition in early life is related to increased cardiovascular risk in adulthood. Graphical Abstract.

Effects of maternal protein restriction on central and peripheral renin-angiotensin systems in male rat offspring

AIMS

We investigated the involvement of the renin angiotensin system (RAS) on the cardiorespiratory control in rats from dams fed with a low-protein diet.

MAIN METHODS

Male offspring were obtained from dams fed a normoprotein diet (NP, 17% casein) and low-protein diet (LP, 8% casein) during pregnancy and lactation. Direct measurements of arterial pressure (AP), heart rate (HR) and respiratory frequency (RF) were recorded in awake 90-day-old at resting and after losartan potassium through either intracerebroventricular (ICV) microinjections or intravenous (IV) administration. Cardiovascular variability was evaluated by spectral analysis. Peripheral chemoreflex sensitivity was assessed through the potassium cyanide (KCN; 40 μg/0.1 ml/rat, IV). Gene expression was evaluated by qPCR, and MAPK (Mitogen Activated Protein Kinase) expression was evaluated by western blot.

KEY FINDINGS

The LP offspring had higher mean AP (MAP) and RF than NP offspring. In the spectral analysis, the LP rats also showed higher low frequency of systolic AP (NP: 2.7 ± 0.3 vs. LP: 5.0 ± 1.0 mmHg). After ICV losartan, MAP and RF in LP rats remained higher than those in NP rats, but without changes in HR. The peripheral chemoreflex was similar between the groups. LP group had lower gene expression of Rac1 (Ras-related C3 botulinum toxin substrate 1) (NP: 1.13 ± 0.06 vs. LP: 0.88 ± 0.08). Peripherally, LP rats had larger delta of MAP after IV losartan (NP: -9.8 ± 2 vs. LP: -23 ± 6 mmHg), without changes in HR and RF.

SIGNIFICANCE

In rats, the RAS participates peripherally, but not centrally, in the maintenance of arterial hypertension in male offspring induced by maternal protein restriction.

Systemic arterial hypertension leads to decreased semen quality and alterations in the testicular microcirculation in rats

Arterial hypertension is a cardiovascular disease that leads to important systemic alterations and drastically impairs normal organ function over time. Hypertension affects around 700 million men of reproductive age and hypertensive men present increased risk for reproductive disorders, such as erectile dysfunction. However, the link between arterial hypertension and male reproductive disorders is associative at best. Moreover, many studies have reported associations between decreased male fertility and/or semen quality and alterations to general male health. In this study we aim to investigate the effect of systemic high blood pressure in sperm quality, sperm functional characteristics and testicular physiology in a rat model. Hypertensive rats presented altered testicular morphology – mainly vascular alterations and impaired testicular vasomotion. Hypertensive rats also presented decrease in sperm concentration, DNA integrity and increased percentages of sperm with dysfunctional mitochondria, intracellular superoxide anion activity and abnormal morphology. This study provides mechanistic insights by which arterial hypertension affects the testes, evidencing the testes as another target organ for hypertension as well as its impact on sperm quality.

Relationship between maternal global nutrient restriction during pregnancy and offspring kidney structure and function: a systematic review of animal studies

Maternal undernutrition during pregnancy is prevalent across the globe, and the origins of many chronic diseases can be traced back to in utero conditions. This systematic review considers the current evidence in animal models regarding the relationship between maternal global nutrient restriction during pregnancy and offspring kidney structure and function. CINAHL, Cochrane, EMBASE, MEDLINE, and Scopus were searched to November 2017. Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines were followed, and articles were screened by two independent reviewers. Twenty-eight studies met the inclusion criteria: 16 studies were on rats, 9 on sheep, 2 on baboons, and 1 on goats. The majority of the rat studies had maternal global nutrient restriction during pregnancy at 50% of ad libitum while restriction for sheep and baboon studies ranged from 50% to 75%. Because of the heterogeneity of outcome measures and the large variation in the age of offspring at followup, no meta-analysis was possible. Common outcome measures included kidney weight, nephron number, glomerular size, glomerular filtration rate, and creatinine clearance. To date, there have been no studies assessing kidney function in large animal models. Most studies were rated as having a high or unknown risk of bias. The current body of evidence in animals suggests that exposure to maternal global nutrient restriction during pregnancy has detrimental effects on offspring kidney structure and function, such as lower kidney weight, lower nephron endowment, larger glomerular size, and lower glomerular filtration rate. Further long-term followup of studies in large animal models investigating kidney function through to adulthood are warranted.

Effects of postweaning calorie restriction on accelerated growth and adiponectin in nutritionally programmed microswine offspring

Poor prenatal development, followed by rapid childhood growth, conveys greater cardiometabolic risk in later life. Microswine offspring exposed to perinatal maternal protein restriction [MPR; "low protein offspring" (LPO)] grow poorly in late-fetal/neonatal stages. After weaning to an ad libitum (AL) diet, LPO-AL exhibit accelerated growth and fat deposition rates with low adiponectin mRNA, despite low-normal body fat and small intra-abdominal adipocytes. We examined effects of caloric restriction (CR) on growth and metabolic status in LPO and normal protein offspring (NPO) randomized to AL or CR diets from weaning. CR transiently reduced growth in both LPO and NPO, delaying recovery in female LPO-CR. Over 7.5-12.5 weeks, linear growth rates in LPO-CR were slower than LPO-AL ( P < 0.001) but exceeded NPO-AL; body weight growth rates fell but were lower in LPO-CR versus NPO-CR. Linear acceleration ceased after 12 weeks. At 16 weeks, percent catch-up in LPO-CR was reduced versus LPO-AL ( P < 0.001). Plasma growth hormone was low in LPO ( P < 0.02). CR normalized fat deposition rate, yet adiponectin mRNA remained low in LPO-CR ( P < 0.001); plasma adiponectin was low in all LPO-AL and in female LPO-CR. Insulin sensitivity improved during CR. We conclude that in LPO: 1) CR delays onset of, but does not abolish, accelerated linear growth, despite low growth hormone; 2) CR yields stunting via delayed onset, plus a finite window for linear growth acceleration; 3) MPR lowers adiponectin mRNA independently of growth, adiposity, or adipocyte size; and 4) MPR reduces circulating adiponectin in LPO-AL and female LPO-CR, potentially enhancing cardiometabolic risk.

Angiotensin receptor blockade in juvenile male rat offspring: Implications for long-term cardio-renal health

Inhibition of the renin-angiotensin system in early postnatal life is a potential therapeutic approach to prevent long-term cardiovascular and kidney diseases in individuals born small. We determined the long-term effects of juvenile losartan treatment on cardiovascular and kidney function in control male rat offspring and those exposed to uteroplacental insufficiency and born small. Bilateral uterine vessel ligation (Restricted) or sham (Control) surgery was performed in late gestation in Wistar Kyoto rats. At weaning, male offspring were randomly assigned to receive losartan in their drinking water or drinking water alone from 5 to 8 weeks of age, and followed to 26 weeks of age. Systolic blood pressure and kidney function were assessed throughout the study. Pressure myography was used to assess passive mechanical wall properties in mesenteric and femoral arteries from 26-week-old offspring. Losartan treatment for three weeks lowered systolic blood pressure in both Control and Restricted groups but this difference was not sustained after the cessation of treatment. Losartan, irrespective of birth weight, mildly increased renal tubulointerstitial fibrosis when assessed at 26 weeks of age. Mesenteric artery stiffness was increased by the early losartan treatment, and was associated with increased collagen and decreased elastin content. Losartan also exerted long-term increases in fat mass and decreases in skeletal muscle mass. In this study, untreated Restricted offspring did not develop hypertension, vascular dysfunction or kidney changes as anticipated. Regardless, we demonstrate that short-term losartan treatment in the juvenile period negatively affects postnatal growth, and kidney and vascular parameters in adulthood, irrespective of birth weight. The long-term effects of early-life losartan treatment warrant further consideration in settings where the potential benefits may outweigh the risks; i.e. when programmed adulthood diseases are apparent and in childhood cardiovascular and kidney diseases.

Treatment with Standard and Low Dose of Conjugated Equine Estrogen Differentially Modulates Estrogen Receptor Expression and Response to Angiotensin II in Mesenteric Venular Bed of Surgically Postmenopausal Hypertensive Rats

Standard hormone therapy for menopausal women [conjugated equine estrogen (CEE) 0.625 mg] has been associated with increased risk of venous thrombosis. Regimens containing a lower CEE dose (0.30 mg) have been used clinically to decrease side effects of supraphysiologic doses of estrogen. In this study, we determined the effects of standard (SD) and low dose (LD) of CEE on venular function in ovariectomized (OVX) spontaneously hypertensive rats (SHR). Contractions by angiotensin-II (Ang-II 10 μM) in perfused mesenteric venular bed were markedly increased in OVX (21.5 ± 1.3 mmHg) compared with Sham (14.7 ± 1.1 mm Hg, P < 0.05). CEE-SD did not modify Ang-II responses in OVX, whereas CEE-LD restored Ang-II contraction to Sham levels. Endothelial nitric oxide synthase (eNOS) inhibition by L-NAME increased Ang-II contractions in Sham and CEE-LD and was without effect in venules of OVX SHR and CEE-SD. In OVX there was decreased NO generation in association with diminished eNOS phosphorylation and increased O2- generation in the venular wall. CEE-LD reverted the deleterious effects of ovariectomy. Although CEE-SD augmented eNOS phosphorylation in OVX, it was unable to increase NO levels, probably owing to its inability to reduce O2- Distinct effects by CEE-SD and CEE-LD parallel the differential modulation of Ang-II and estrogen receptors. Compared with Sham, CEE-LD increases Ang II receptor type 2, whereas CEE-SD modified ERβ expression in the venous bed. Interestingly, both CEE doses increased G protein-coupled estrogen receptor in OVX. Our data suggest that estrogen dose is an important factor for venous function. Although CEE-LD reversed deleterious effects of OVX, CEE-SD showed null effects despite its ability to increase eNOS activity.

Intrauterine growth restriction programs an accelerated age-related increase in cardiovascular risk in male offspring

Placental insufficiency programs an increase in blood pressure associated with a twofold increase in serum testosterone in male growth-restricted offspring at 4 mo of age. Population studies indicate that the inverse relationship between birth weight and blood pressure is amplified with age. Thus, we tested the hypothesis that intrauterine growth restriction programs an age-related increase in blood pressure in male offspring. Growth-restricted offspring retained a significantly higher blood pressure at 12 but not at 18 mo of age compared with age-matched controls. Blood pressure was significantly increased in control offspring at 18 mo of age relative to control counterparts at 12 mo; however, blood pressure was not increased in growth-restricted at 18 mo relative to growth-restricted counterparts at 12 mo. Serum testosterone levels were not elevated in growth-restricted offspring relative to control at 12 mo of age. Thus, male growth-restricted offspring no longer exhibited a positive association between blood pressure and testosterone at 12 mo of age. Unlike hypertension in male growth-restricted offspring at 4 mo of age, inhibition of the renin-angiotensin system with enalapril (250 mg/l for 2 wk) did not abolish the difference in blood pressure in growth-restricted offspring relative to control counterparts at 12 mo of age. Therefore, these data suggest that intrauterine growth restriction programs an accelerated age-related increase in blood pressure in growth-restricted offspring. Furthermore, this study suggests that the etiology of increased blood pressure in male growth-restricted offspring at 12 mo of age differs from that at 4 mo of age.

Changes of blood pressure, abdominal visceral fat tissue and gene expressions in fetal programming induced rat model after amlodipine-losartan combination treatment

Background

There are a number of complications that can occur if there is under-nutrition during pregnancy followed by a period of rapid catch-up growth, including a higher chance of adult obesity, insulin resistance and hypertriglyceridemia. The purposes of this study were to investigate the effects of fetal under-nutrition during late pregnancy and lactation on blood pressure, visceral fat tissue, gene expressions and to evaluate changes after amlodipine- losartan combination treatment.

Methods

The rats were divided into three groups: the control (C) group, the food restriction (FR: 50 % food restricted diet) group, and the CX group, which was treated with Cozaar XQ (amlodipine- losartan combination drug) in FR rats from postnatal 4 to 20 weeks. Masson’s trichrome staining was performed in the heart tissues. The amount of abdominal visceral fat tissues was measured. Western blot analysis such as angiotensin converting enzyme (ACE), angiotensin II receptor type IA (ATIA), troponin I (Tn I) and endothelial nitric oxide synthase (eNOS) were performed.

Results

Body weights were significantly higher in the FR group compared with the C group at weeks 8 and 20 and lower in the CX group at week 20. Blood pressure was significantly higher in the FR group compared with the C group at week 20 and lower in the CX group at weeks 12 and 20. The amount of abdominal visceral fat was significantly higher in the FR group compared with the C group at weeks 8, 12 and 20 and significantly lower in the CX group at weeks 16 and 20. Protein expression of ATIA and eNOS were significantly reduced in the CX group at weeks 16 and 20. ACE was significantly reduced in the CX group at week 20 and Tn I was significantly reduced in the CX group at week 16.

Conclusions

When there is fetal under-nutrition during pregnancy, it leads to obesity, high blood pressure, hypertriglyceridemia and several gene changes in offspring. Amlodipine-losartan combination treatment was able to lower obesity, hypertension, hypertriglyceridemia and several gene changes in rats suffering from fetal under-nutrition during pregnancy.

The implication of protein malnutrition on cardiovascular control systems in rats

The malnutrition in early life is associated with metabolic changes and cardiovascular impairment in adulthood. Deficient protein intake-mediated hypertension has been observed in clinical and experimental studies. In rats, protein malnutrition also increases the blood pressure and enhances heart rate and sympathetic activity. In this review, we discuss the effects of post-weaning protein malnutrition on the resting mean arterial pressure and heart rate and their variabilities, cardiovascular reflexes sensitivity, cardiac autonomic balance, sympathetic and renin-angiotensin activities and neural plasticity during adult life. These insights reveal an interesting prospect on the autonomic modulation underlying the cardiovascular imbalance and provide relevant information on preventing cardiovascular diseases.

Mechanisms involved in developmental programming of hypertension and renal diseases. Gender differences

BACKGROUND

A substantial body of epidemiological and experimental evidence suggests that a poor fetal and neonatal environment may "program" susceptibility in the offspring to later development of cardiovascular, renal and metabolic diseases.

MATERIALS AND METHODS

This review focuses on current knowledge from the available literature regarding the mechanisms linking an adverse developmental environment with an increased risk for cardiovascular, renal and metabolic diseases in adult life. Moreover, this review highlights important sex-dependent differences in the adaptation to developmental insults.

RESULTS

Developmental programming of several diseases is secondary to changes in different mechanisms inducing important alterations in the normal development of several organs that lead to significant changes in birth weight. The different diseases occurring as a consequence of an adverse environment during development are secondary to morphological and functional cardiovascular and renal changes, to epigenetic changes and to an activation of several hormonal and regulatory systems, such as angiotensin II, sympathetic activity, nitric oxide, COX2-derived metabolites, oxidative stress and inflammation. The important sex-dependent differences in the developmental programming of diseases seem to be partly secondary to the effects of sex hormones. Recent studies have shown that the progression of these diseases is accelerated during aging in both sexes.

CONCLUSIONS

The cardiovascular, renal and metabolic diseases during adult life that occur as a consequence of several insults during fetal and postnatal periods are secondary to multiple structural and functional changes. Future studies are needed in order to prevent the origin and reduce the incidence and consequences of developmental programmed diseases.

Enhanced mesenteric arterial responsiveness to angiotensin II is androgen receptor-dependent in prenatally protein-restricted adult female rat offspring

Gestational protein restriction results in intrauterine growth restriction and hypertension in adult female growth-restricted rats. Enhanced vascular responsiveness to angiotensin II is observed, and blockade of the renin-angiotensin system abolishes hypertension in adult growth-restricted rats, suggesting that the renin-angiotensin system contributes to intrauterine growth restriction-induced hypertension. Moreover, growth-restricted adult rats have higher plasma testosterone levels, and antiandrogen treatment abolishes hypertension, indicating an important role for testosterone. We hypothesized that androgens may play a pivotal role in the enhanced responsiveness to Ang II and hypertension. Female offspring of pregnant rats fed 20% protein (control) or 6% protein diet (protein restricted), at 6 mo of age, were studied. Plasma testosterone and mean arterial pressure in protein-restricted offspring were significantly higher compared to controls. Flutamide treatment (10 mg/kg/day subcutaneously for 10 days) reduced mean arterial pressure in protein-restricted offspring but was without significant effect in controls. Vascular Agtr1/Agtr2 ratio was significantly higher in protein-restricted offspring, an effect that was reversed by flutamide. Flutamide treatment did not have any effect on Agtr1/Agtr2 ratio in controls. Enhanced contractile response to angiotensin II in mesenteric arteries was observed in protein-restricted offspring compared with control. Flutamide treatment reversed the enhanced contractile response to angiotensin II in protein-restricted offspring without significant effect in controls. Vascular reactivity to phenylephrine was similar between the control and protein-restricted offspring with and without flutamide treatment, suggesting that enhanced contractile response and flutamide's reversal effect is specific to angiotensin II. These results suggest that prenatally protein-restricted rats exhibit an enhanced responsiveness to angiotensin II that is testosterone-dependent.

Influence of aerobic training on the reduced vasoconstriction to angiotensin II in rats exposed to intrauterine growth restriction: possible role of oxidative stress and AT2 receptor of angiotensin II

Intrauterine growth restriction (IUGR) is associated with impaired vascular function, which contributes to the increased incidence of chronic disease. The aim of this study was to investigate whether aerobic training improves AngII-induced vasoconstriction in IUGR rats. Moreover, we assess the role of superoxide dismutase (SOD) isoforms and NADPH oxidase-derived superoxide anions in this improvement. Female Wistar rats were randomly divided into two groups on day 1 of pregnancy. A control group was fed standard chow ad libitum, and a restricted group was fed 50% of the ad libitum intake throughout gestation. At 8 weeks of age, male offspring from both groups were randomly assigned to 4 experimental groups: sedentary control (SC), trained control (TC), sedentary restricted (SRT), and trained restricted (TRT). The training protocol was performed on a treadmill and consisted of a continuous 60-min session 5 days/week for 10 weeks. Following aerobic training, concentration–response curves to AngII were obtained in endothelium-intact aortic rings. Protein expression of SOD isoforms, AngII receptors and the NADPH oxidase component p47^phox was assessed by Western blot analysis. The dihydroethidium was used to evaluate the in situ superoxide levels under basal conditions or in the presence of apocynin, losartan or PD 123,319. Our results indicate that aerobic training can prevent IUGR-associated increases in AngII-dependent vasoconstriction and can restore basal superoxide levels in the aortic rings of TRT rats. Moreover, we observed that aerobic training normalized the increased p47^phox protein expression and increased MnSOD and AT₂ receptor protein expression in thoracic aortas of SRT rats. In summary, aerobic training can result in an upregulation of antioxidant defense by improved of MnSOD expression and attenuation of NADPH oxidase component p47^phox. These effects are accompanied by increased expression of AT₂ receptor, which provide positive effects against Ang II–induced superoxide generation, resulting in attenuation of AngII-induced vasoconstriction.

Mechanisms involving Ang II and MAPK/ERK1/2 signaling pathways underlie cardiac and renal alterations during chronic undernutrition

Background

Several studies have correlated protein restriction associated with other nutritional deficiencies with the development of cardiovascular and renal diseases. The driving hypothesis for this study was that Ang II signaling pathways in the heart and kidney are affected by chronic protein, mineral and vitamin restriction.

Methodology/Principal Findings

Wistar rats aged 90 days were fed from weaning with either a control or a deficient diet that mimics those used in impoverished regions worldwide. Such restriction simultaneously increased ouabain-insensitive Na⁺-ATPase and decreased (Na⁺+K⁺)ATPase activity in the same proportion in cardiomyocytes and proximal tubule cells. Type 1 angiotensin II receptor (AT₁R) was downregulated by that restriction in both organs, whereas AT₂R decreased only in the kidney. The PKC/PKA ratio increased in both tissues and returned to normal values in rats receiving Losartan daily from weaning. Inhibition of the MAPK pathway restored Na⁺-ATPase activity in both organs. The undernourished rats presented expanded plasma volume, increased heart rate, cardiac hypertrophy, and elevated systolic pressure, which also returned to control levels with Losartan. Such restriction led to electrical cardiac remodeling represented by prolonged ventricular repolarization parameters, induced triggered activity, early after-depolarization and delayed after-depolarization, which were also prevented by Losartan.

Conclusion/Significance

The mechanisms responsible for these alterations are underpinned by an imbalance in the PKC- and PKA-mediated pathways, with participation of angiotensin receptors and by activation of the MAPK/ERK1/2 pathway. These cellular and molecular alterations culminate in cardiac electric remodeling and in the onset of hypertension in adulthood.

The microvasculature: a target for nutritional programming and later risk of cardio-metabolic disease

There is compelling evidence that microvascular deficits affecting multiple tissues and organs play an important role in the aetiopathogenesis of cardio-metabolic disease. Furthermore, both in humans and animal models, deficits in small vessel structure and function can be detected early, often before the onset of macrovascular disease and the development of end-organ damage that is common to hypertension and obesity-associated clinical disorders. This article considers the growing evidence for the negative impact of an adverse maternal diet on the long-term health of her child, and how this can result in a disadvantageous vascular phenotype that extends to the microvascular bed. We describe how structural and functional modifications in the offspring microcirculation during development may represent an important and additional risk determinant to increase susceptibility to the development of cardio-metabolic disease in adult life and consider the cell-signalling pathways associated with endothelial dysfunction that may be 'primed' by the maternal environment. Published studies were identified that reported outcomes related to the microcirculation, endothelium, maternal diet and vascular programming using NCBI PubMed.gov, MEDLINE and ISI Web of Science databases from 1980 until April 2013 using pre-specified search terms. Information extracted from over 230 original reports and review articles was critically evaluated by the authors for inclusion in this review.

COX2 inhibition during nephrogenic period induces ANG II hypertension and sex-dependent changes in renal function during aging

This study was performed to test the hypothesis that ANG II contributes to the hypertension and renal functional alterations induced by a decrease of COX2 activity during the nephrogenic period. It was also examined whether renal functional reserve and renal response to volume overload and high sodium intake are reduced in 3-4- and 9-11-mo-old male and female rats treated with vehicle or a COX2 inhibitor during nephrogenic period (COX2np). Our data show that this COX2 inhibition induces an ANG II-dependent hypertension that is similar in male and female rats. Renal functional reserve is reduced in COX2np-treated rats since their renal response to an increase in plasma amino acids levels is abolished, and their renal ability to eliminate a sodium load is impaired (P < 0.05). This reduction in renal excretory ability is similar in both sexes during aging but does not induce the development of a sodium-sensitive hypertension. However, the prolonged high-sodium intake at 9-11 mo of age leads to a greater proteinuria in male than in female (114 ± 12 μg/min vs. 72 ± 8 μg/min; P < 0.05) COX2np-treated rats. Renal hemodynamic sensitivity to acute increments in ANG II is unaltered in both sexes and at both ages in COX2np-treated rats. In summary, these results indicate that the reduction of COX2 activity during nephrogenic period programs for the development of an ANG II-dependent hypertension, reduces renal functional reserve to a similar extent in both sexes, and increases proteinuria in males but not in females when there is a prolonged increment in sodium intake.

The fetal origins of hypertension: a systematic review and meta-analysis of the evidence from animal experiments of maternal undernutrition

OBJECTIVE

Numerous experiments in animals have been performed to investigate the effect of prenatal undernutrition on the development of hypertension in later life, with inconclusive results. We systematically reviewed animal studies examining the effects of maternal undernutrition on SBP, DBP, and mean arterial blood pressure (BP) in offspring.

METHODS

A search was performed in Medline and Embase to identify articles that reported on maternal undernutrition and hypertension in experimental animal studies. Summary estimates of the effect of undernutrition on SBP, DBP, and mean arterial BP were obtained through meta-analysis.

RESULTS

Of the 6151 articles identified, 194 were considered eligible after screening titles and abstracts. After detailed evaluation, 101 met the inclusion criteria and were included in the review. Both maternal general and protein undernutrition increased SBP [general undernutrition: 14.5 mmHg, 95% confidence interval (CI) 10.8-18.3; protein undernutrition: 18.9 mmHg, 95% CI 16.1-21.8] and mean arterial BP (general undernutrition: 5.0 mmHg, 95% CI 1.4-8.6; protein undernutrition: 10.5 mmHg, 95% CI 6.7-14.2). There was substantial heterogeneity in the results. DBP was increased by protein undernutrition (9.5 mmHg, 95% CI 2.6-16.3), whereas general undernutrition had no significant effect.

CONCLUSION

The results of this meta-analysis generally support the view that in animals, maternal undernutrition--both general and protein--results in increased SBP and mean arterial BP. DBP was only increased after protein undernutrition. The results depended strongly on the applied measurement technique and animal model.

Role of angiotensin II in arterial pressure and renal hemodynamics in rats with altered renal development: age- and sex-dependent differences

Numerous studies have demonstrated that angiotensin II (ANG II) is involved in hypertension and renal changes occurring as a consequence of an adverse event during renal development. However, it was unknown whether this involvement is sex and age dependent. This study examines whether the increments in arterial pressure (AP) and in the renal sensitivity to ANG II are sex and age dependent in rats with altered renal development. It also evaluates whether the ANG II effects are accompanied by increments in AT(1) receptors and oxidative stress. Experiments were performed in 3- to 4- and 10- to 11-mo-old rats treated with vehicle or an AT(1) receptor antagonist (ARAnp) during the nephrogenic period. ARAnp-treated rats were hypertensive, but an age-dependent rise in AP was only found in males. Three days of treatment with candesartan (7 mg·kg(-1)·day(-1)) led to a fall of AP that was greater (P < 0.05) in male than in female 10- to 11-mo-old ARAnp-treated rats. Oxidated proteins were elevated (P < 0.05), and the decrease in AP elicited by candesartan was reduced (P < 0.05) when these rats are also treated with tempol (18 mg·kg(-1)·day(-1)). Hypertension was not maintained by an elevation of AT(1) receptors in kidneys and mesenteric arteries. The acute renal hemodynamic response to ANG II (30 ng·kg(-1)·min(-1)) was similarly enhanced (P < 0.05) in both sexes of ARAnp-treated rats at 3-4 but not at 10-11 mo of age. Our results suggest that an adverse event during the nephrogenic period induces an ANG II-dependent increment in AP that is aggravated only in males during aging and that oxidative stress but not an increase in AT(1) receptor contributes to the rise in AP. This study also shows that the renal hemodynamic sensitivity to ANG II is transitorily enhanced in both sexes of rats with altered renal development.

Faria T, Siman FDM, Silveira EA, Meira EF, da Costa CP, Vassallo DV, Padilha AS. Post-weaning protein malnutrition increases blood pressure and induces endothelial dysfunctions in rats

Malnutrition during critical periods in early life may increase the subsequent risk of hypertension and metabolic diseases in adulthood, but the underlying mechanisms are still unclear. We aimed to evaluate the effects of post-weaning protein malnutrition on blood pressure and vascular reactivity in aortic rings (conductance artery) and isolated-perfused tail arteries (resistance artery) from control (fed with Labina®) and post-weaning protein malnutrition rats (offspring that received a diet with low protein content for three months). Systolic and diastolic blood pressure and heart rate increased in the post-weaning protein malnutrition rats. In the aortic rings, reactivity to phenylephrine (10(-10)-3.10(-4) M) was similar in both groups. Endothelium removal or L-NAME (10(-4) M) incubation increased the response to phenylephrine, but the L-NAME effect was greater in the aortic rings from the post-weaning protein malnutrition rats. The protein expression of the endothelial nitric oxide isoform increased in the aortic rings from the post-weaning protein malnutrition rats. Incubation with apocynin (0.3 mM) reduced the response to phenylephrine in both groups, but this effect was higher in the post-weaning protein malnutrition rats, suggesting an increase of superoxide anion release. In the tail artery of the post-weaning protein malnutrition rats, the vascular reactivity to phenylephrine (0.001-300 µg) and the relaxation to acetylcholine (10(-10)-10(-3) M) were increased. Post-weaning protein malnutrition increases blood pressure and induces vascular dysfunction. Although the vascular reactivity in the aortic rings did not change, an increase in superoxide anion and nitric oxide was observed in the post-weaning protein malnutrition rats. However, in the resistance arteries, the increased vascular reactivity may be a potential mechanism underlying the increased blood pressure observed in this model.

Acute AT(1)-receptor blockade reverses the hemodynamic and baroreflex impairment in adult sheep exposed to antenatal betamethasone

To accelerate lung development and protect neonates from other early developmental problems, synthetic steroids are administered maternally in the third trimester, exposing fetuses that are candidates for premature delivery to them. However, steroid exposure at this point of gestation may lead to elevated blood pressure [mean arterial pressure (MAP)] during adolescence. We hypothesize that fetal exposure to steroids activates the renin-angiotensin system, inducing an elevation in blood pressure and attenuation of baroreflex sensitivity (BRS) that is angiotensin II dependent in early adulthood. To test this hypothesis, fetal sheep were exposed to betamethasone (Beta) or vehicle (control) administered to ewes at day 80 of gestation and delivered at full term. At 1.8 yr of age, male offspring were instrumented for conscious recording of MAP, heart rate, and measurement of BRS [as low-frequency-alpha, high-frequency-alpha, sequence (seq) UP, seq DOWN, and seq TOTAL]. Beta-exposed sheep (n = 6) had higher MAP than control sheep (n = 5) (93 + or - 2 vs. 84 + or - 2 mmHg, P < 0.01). Acute blockade of angiotensin type 1 receptors with candesartan (0.3 mg/kg iv) normalized MAP in Beta-exposed sheep (85 + or - 4 mmHg), with no effect in control sheep (82 + or - 3 mmHg). Before angiotensin type 1 blockade, BRS maximum gain was significantly lower in Beta-exposed vs. control sheep (11 + or - 3 vs. 26 + or - 3 ms/mmHg, P < 0.0.01). However, 45 min after candesartan injection, BRS was increased in Beta-exposed (21 + or - 5 ms/mmHg) and control (35 + or - 4 ms/mmHg) sheep. Heart rate variability (HRV) and blood pressure variability (BPV) revealed lower HRV (SD of beat-to-beat interval and root mean square of successive beat-to-beat differences in R-R interval duration) and higher BPV (SD of MAP, systolic arterial pressure in low-frequency range) in Beta-exposed sheep. Candesartan partially restored HRV in Beta-exposed sheep and fully corrected BPV. Thus, in utero exposure to synthetic glucocorticoids causes long-lasting programming of the cardiovascular system via renin-angiotensin system-dependent mechanisms.

Role of fetal programming in the development of hypertension

Epidemiological studies have suggested that size at birth contributes to increased cardiovascular disease (CVD) risk in later life. Findings from experimental studies are providing insight into the mechanisms linking impaired fetal growth and the increased risk of CVD and hypertension in adulthood. This article summarizes potential mechanisms involved in the fetal programming of hypertension and CVD, including alterations in the organs and regulatory systems critical to long-term control of sodium and volume homeostasis.

Role of the kidney in the prenatal and early postnatal programming of hypertension

Epidemiologic studies from several different populations have demonstrated that prenatal insults, which adversely affect fetal growth, result in an increased incidence of hypertension when the offspring reaches adulthood. It is now becoming evident that low-birth-weight infants are also at increased risk for chronic kidney disease. To determine how prenatal insults result in hypertension and chronic kidney disease, investigators have used animal models that mimic the adverse events that occur in pregnant women, such as dietary protein or total caloric deprivation, uteroplacental insufficiency, and prenatal administration of glucocorticoids. This review examines the role of the kidney in generating and maintaining an increase in blood pressure in these animal models. This review also discusses how early postnatal adverse events may have repercussions in later life. Causes for the increase in blood pressure by perinatal insults are likely multifactorial and involve a reduction in nephron number, dysregulation of the systemic and intrarenal renin-angiotensin system, increased renal sympathetic nerve activity, and increased tubular sodium transport. Understanding the mechanism for the increase in blood pressure and renal injury resulting from prenatal insults may lead to therapies that prevent hypertension and the development of chronic kidney and cardiovascular disease.

Micronutrient prenatal supplementation prevents the development of hypertension and vascular endothelial damage induced by intrauterine malnutrition

AIMS

The premise that intrauterine malnutrition plays an important role in the development of cardiovascular and renal diseases implies that these disorders can be programmed during fetal life. Here, we analyzed the hypothesis that supplementation with mixed antioxidant vitamins and essential mineral in early life could prevent later elevation of blood pressure and vascular and renal dysfunction associated with intrauterine malnutrition.

MAIN METHODS

For this, female Wistar rats were randomly divided into three groups on day 1 of pregnancy: control fed standard chow ad libitum; restricted group fed 50% of the ad libitum intake and a restricted plus micronutrient cocktail group treated daily with a combination of micronutrient (selenium, folate, vitamin C and vitamin E) by oral gavage.

KEY FINDINGS

In adult offspring, renal function and glomerular number were impaired by intrauterine malnutrition, and the prenatal micronutrient treatment did not prevent it. However, increased blood pressure and reduced endothelium-dependent vasodilation were prevented by the micronutrient prenatal treatment. Intrauterine malnutrition also led to reduced NO production associated with increased superoxide generation, and these parameters were fully normalized by this prenatal treatment.

SIGNIFICANCE

Our current findings indicate that programming alterations during fetal life can be prevented by interventions during the prenatal period, and that disturbance in availability of both antioxidant vitamins and mineral may play a crucial role in determining the occurrence of long-term cardiovascular injury.

Stunting growth: association of the blood pressure levels and ACE activity in early childhood

Angiotensin converting enzyme (ACE) converts angiotensin I to angiotensin II and inactive bradykinin. Several studies carried out in our laboratory have consistently identified three isoforms of ACE, at 65, 90 and 190 kDa, with the 90-kDa isoform being a possible genetic marker of hypertension. Based on these observations and the fact that nutritional stunting can be associated with hypertension, we have investigated the expression and activity of ACE in stunted children and its association with blood pressure (BP) levels and nutritional state. Sixty children aged 2-7 years were selected for this study. A urine sample was collected from each child. Angiotensin converting enzyme activity was evaluated using two different substrates, and ACE expression was detected by Western blotting. Our results show that nutritional stunting is associated with high ACE activity in childhood and that adjustment by gender does not modify the strength of this association. A greater percentage of stunted children had increased BP levels, and this clinical parameter was inversely correlated with anthropometric indicators. A greater urinary protein expression of the three ACE isoforms was observed in the group of children with growth stunting. Our findings suggest that the reported high risk of hypertension in stunted adolescents and adults are, at least partly, associated with abnormalities in the renin-angiotensin system.

Effects of maternal undernutrition on renal angiotensin II and chymase in hypertensive offspring

Intrauterine growth restriction (IUGR) can program the future development of hypertension in adulthood. The renin-angiotensin system has been reported to play a role in IUGR-induced hypertension. The aims of this study were to investigate the effects of IUGR on renal angiotensin-converting enzyme (ACE), angiotensin II (Ang II) and chymase in IUGR-induced hypertension. Timed pregnant Sprague-Dawley rats received 50% rations of control food intakes from days 15 to 21 of gestation. Control rats received regular food throughout the pregnancies. Arterial blood pressure and glomerular number were measured and immunohistochemical studies were performed on kidney tissues in adult male offspring at 16 weeks of age. IUGR rats exhibited significantly lower body and kidney weights and reduced number of glomeruli when compared with control rats. IUGR rats had significantly higher systolic blood pressure than control rats. Immunoreactivity of ACE was comparable between control and IUGR rats whereas immunoreactivities of chymase and Ang II were significantly higher in IUGR rats than in control rats. In conclusion, immunohistochemical studies document up-regulation of ACE-independent Ang II and chymase in IUGR kidney and indicate that overactivity of chymase may result in increased intrarenal Ang II production, which could contribute to the development of hypertension in intrauterine undernourished rats.

Sex differences in the fetal programming of hypertension

BACKGROUND

Numerous clinical and experimental studies support the hypothesis that the intrauterine environment is an important determinant of cardiovascular disease and hypertension.

OBJECTIVE

This review examined the mechanisms linking an adverse fetal environment and increased risk for chronic disease in adulthood with an emphasis on gender differences and the role of sex hormones in mediating sexual dimorphism in response to a suboptimal fetal environment.

METHODS

This review focuses on current findings from the PubMed database regarding animal models of fetal programming of hypertension, sex differences in phenotypic outcomes, and potential mechanisms in offspring of mothers exposed to an adverse insult during gestation. For the years 1988 to 2007, the database was searched using the following terms: fetal programming, intrauterine growth restriction, low birth weight, sex differences, estradiol, testosterone, high blood pressure, and hypertension.

RESULTS

The mechanisms involved in the fetal programming of adult disease are multifactorial and include alterations in the regulatory systems affecting the long-tterm control of arterial pressure. Sex differences have been observed in animal models of fetal programming, and recent studies suggest that sex hormones may modulate activity of regulatory systems, leading to a lower incidence of hypertension and vascular dysfunction in females compared with males.

CONCLUSIONS

Animal models of fetal programming provide critical support for the inverse relationship between birth weight and blood pressure. Experimental models demonstrate that sex differences are observed in the pathophysiologic response to an adverse fetal environment. A role for sex hormone involvement is strongly suggested,with modulation of the renin-angiotensin system as a possible mechanism.

Circulating renin-angiotensin system and catecholamines in childhood: is there a role for birthweight?

There have been only a few reports on the sympathoadrenal and renin-angiotensin systems in children of small gestational age. The purpose of the present study was to investigate plasma levels of ACE (angiotensin-converting enzyme) activity, angiotensin and catecholamines in 8- to 13-year-old children and to determine whether there are correlations between the components of these systems with both birthweight and BP (blood pressure) levels. This clinical study included 66 children (35 boys and 31 girls) in two groups: those born at term with an appropriate birthweight [AGA (appropriate-for-gestational age) group, n=31] and those born at term but with a small birthweight for gestational age [SGA (small-for-gestational age) group, n=35]. Concentrations of angiotensin, catecholamines and ACE activity were determined in plasma. Circulating noradrenaline levels were significantly elevated in SGA girls compared with AGA girls (P=0.036). In addition, angiotensin II and ACE activity were higher in SGA boys (P=0.024 and P=0.050 respectively). There was a significant association of the circulating levels of both angiotensin II and ACE activity with BP levels in our study population. Although the underlying mechanisms that link restricted fetal growth with later cardiovascular events are not fully understood, the findings in the present study support the link between low birthweight and overactivity of both sympathoadrenal and renin-angiotensin systems into later childhood.

Angiotensin II Chronic Infusion Induces B1 Receptor Expression in Aorta of Rats

We investigated whether angiotensin II infusion modulates in vivo the kinin B1 receptor expression and the mechanisms involved in this process. We also evaluated the role of the B1 receptor activation in aorta. Wistar rats received 400 ng/kg per minute of angiotensin II or saline (control rats) infusion during 14 days through an osmotic minipump. To investigate the role of superoxide anion in B1 receptor expression, rats received a reduced nicotinamide-adenine dinucleotide phosphate oxidase inhibitor in the drinking water during 14 days (60 mg/L of apocynin) simultaneously with angiotensin II infusion. Angiotensin II induced B1 receptor expression in the aorta and increased significantly systolic blood pressure, superoxide anion, and the nuclear factor κB activity. Apocynin treatment did not alter the blood pressure levels of angiotensin II rats and reduced the B1 receptor expression, superoxide anion generation, and nuclear factor κB activity to similar levels of the control rats. Vascular reactivity studies in isolated aorta reveal that B1 receptor agonist promoted endothelium-dependent dilation and increased the NO generation in aorta of angiotensin II rats. NO synthase inhibitor and B1 receptor antagonist inhibited the vasodilation and NO generation, which were not affected by B2 receptor antagonist or indomethacin. These results provide evidence that angiotensin II induces B1 receptor expression in aorta by superoxide anion generation, via reduced nicotinamide-adenine dinucleotide phosphate oxidase, concomitant to nuclear factor κB activation. We have also shown that B1 receptor agonist causes endothelium-dependent vasodilation through NO production in aortic rings, suggesting that the B1 receptor expression could be related with the vascular tonus control of angiotensin II rats.