Developmental Programming of Hypertension: Physiological Mechanisms

Biphasic effects of single-dose intravenous injection of uridine adenosine tetraphosphate on blood pressure in mice

PURPOSE

To explore the effects of a single dose of uridine adenosine tetraphosphate (Up4A) administered through the tail vein, on the blood pressure of mice.

METHODS

The mice were separated into three groups: the Up4A group, the norepinephrine (NA) group, and the α, β-methylene adenosine triphosphate (α, β-meATP) group. Each group of mice were injected drugs through the tail vein at 1, 3, 10, and 30 nmol/kg doses in an ascending order. Additionally, six mice were injected Up4A through the tail vein at 20, 40, 60, and 80 nmol/kg doses in an ascending order. The administration intervals for each dose were 20 min.

RESULTS

Mice in these groups experienced a rapid increase in blood pressure, reaching its peak within 10 s after drug administration. It took approximately 120 s for the blood pressure to return to baseline levels after the administration of the drugs in both the NA and α, β-meATP groups. After higher doses of Up4A were administered to the mice, their blood pressure exhibited biphasic changes. Initially, blood pressure of the mice rapidly dropped to a minimum within 10 s, then rose rapidly to a peak within 30 s. Subsequently, it gradually declined, taking around 10 min to return to the levels before the drug administration.

CONCLUSION

Compared to NA and α, β-meATP, Up4A, which contains purine and pyrimidine components, displayed a weaker blood pressure-elevating potency. Through its corresponding structure, Up4A exerted vasodilatory and vasoconstrictive effects throughout the entire experiment resulting in biphasic changes in blood pressure.

Salt-Sensitive Hypertension and the Kidney

Salt-sensitive hypertension (SS-HT) is characterized by blood pressure elevation in response to high dietary salt intake and is considered to increase the risk of cardiovascular and renal morbidity. Although the mechanisms responsible for SS-HT are complex, the kidneys are known to play a central role in the development of SS-HT and the salt sensitivity of blood pressure (SSBP). Moreover, several factors influence renal function and SSBP, including the renin-angiotensin-aldosterone system, sympathetic nervous system, obesity, and aging. A phenotypic characteristic of SSBP is aberrant activation of the renin-angiotensin system and sympathetic nervous system in response to excessive salt intake. SSBP is also accompanied by a blunted increase in renal blood flow after salt loading, resulting in sodium retention and SS-HT. Obesity is associated with inappropriate activation of the aldosterone mineralocorticoid receptor pathway and renal sympathetic nervous system in response to excessive salt, and mineralocorticoid receptor antagonists and renal denervation attenuate sodium retention and inhibit salt-induced blood pressure elevation in obese dogs and humans. SSBP increases with age, which has been attributed to impaired renal sodium handling and a decline in renal function, even in the absence of kidney disease. Aging-associated changes in renal hemodynamics are accompanied by significant alterations in renal hormone levels and renal sodium handling, resulting in SS-HT. In this review, we focus mainly on the contribution of renal function to the development of SS-HT.

Sex Differences in Offspring of Preeclamptic Pregnancies

A poor uterine environment causes changes in fetal development that affect the health of offspring long-term. Although there are multiple pathways that contribute to the development of cardiovascular and neurological disease, low birth weight or fetal growth restriction (FGR) predisposes offspring to these diseases. There is a link between fetal exposure to adverse influences and hypertension later in life. Many epidemiological studies support the link between fetal life and the risk of disease later in life. Experimental models have sought to provide mechanistic proof of this link while simultaneously investigating potential therapeutics or treatment pathways. Preeclampsia (PE), one of several hypertensive disorders in pregnancy, is a leading cause of morbidity and mortality for both the mother and fetus. Studies have shown that PE is a state of chronic inflammation and there is an imbalance between pro-inflammatory and regulatory immune cells and mediators. There is no cure for PE beyond the delivery of the fetal-placental unit, and many PE pregnancies result in FGR and preterm birth. Epidemiological data demonstrate that the sex of the offspring is correlated with the degree of cardiovascular disease that develops with the age of the offspring yet few studies examine the effect of sex on the development of neurological disorders. Even fewer studies examine the effects of therapeutics on offspring of different genders following a PE pregnancy. Moreover, there remain significant gaps in knowledge concerning the role the immune system plays in FGR offspring developing hypertension or neurovascular disorders later in life. Therefore, the purpose of this review is to highlight current research on sex differences in the developmental programming of hypertension and neurological disorders following a PE pregnancy.

Mechanisms of sex and gender differences in hypertension

The mechanisms that control blood pressure are multifaceted including the sympathetic nervous system and the renin-angiotensin system leading to vasoconstriction and sodium reabsorption that causes a shift in the pressure-natriuesis relationship to higher blood pressures. Sex steroids can affect these mechanisms either directly or indirectly, and the effects may be different depending on the sex of the individual. This review will discuss some of the major blood pressure-controlling mechanisms and how sex steroids may affect them and the need for future studies to better clarify the mechanisms responsible for sex and gender differences in blood pressure control. New mechanisms that are identified, along with what is already known, will provide better tools for treatment of hypertension in men and women of all ethnicities and decrease the risk of cardiovascular disease in the future.

Inhibition of angiotensin II type 1 receptor agonistic autoantibodies by direct binding does not impact reduced uterine perfusion pressure offspring birthweight and blood pressure at adulthood

BACKGROUND

Preeclampsia, a new-onset hypertension with end-organ damage in pregnancy, is associated with maternal death and morbidity, low birthweight, and B cells producing agonistic autoantibodies to the angiotensin II type 1 receptor. Angiotensin II type 1 receptor agonistic autoantibodies are produced during pregnancy and after delivery and are in the fetal circulation of women with preeclampsia. Angiotensin II type 1 receptor agonistic autoantibodies are shown to contribute to endothelial dysfunction, renal dysfunction, hypertension, fetal growth restriction, and chronic inflammation in women with preeclampsia. The reduced uterine perfusion pressure rat model of preeclampsia exhibits these features. In addition, we have shown that the administration of a 'n7AAc', which blocks the actions of the angiotensin II type 1 receptor autoantibodies, improves preeclamptic features in the rat with reduced uterine perfusion pressure. However, the effect of a 'n7AAc' on the long-term health of the offspring of rats with reduced uterine perfusion pressure is unknown.

OBJECTIVE

This study aimed to test the hypothesis that inhibition of angiotensin II type 1 receptor autoantibodies during pregnancy will improve offspring birthweight and prevent increased cardiovascular risk in offspring in adulthood.

STUDY DESIGN

To test our hypothesis, a 'n7AAc' (24 µg/d) or vehicle (saline) was given on gestation day 14 via miniosmotic pumps to sham-operated (sham) and Sprague-Dawley rat dams with reduced uterine perfusion pressure. Dams were allowed to deliver naturally, and pup weights were recorded within 12 hours after birth. Pups were aged to 16 weeks, at which time mean arterial pressure was measured and whole blood was collected to measure immune cells by flow cytometry, cytokines by enzyme-linked immunosorbent assay, and angiotensin II type 1 receptor autoantibodies by bioassay. A 2-way analysis of variance with the Bonferroni multiple comparison posthoc test was used for statistical analysis.

RESULTS

There was no significant change in offspring birthweight of 'n7AAc'-treated male (5.63±0.09 g) or female (5.66±0.14 g) offspring from reduced uterine perfusion pressure dams compared with vehicle male (5.51±0.17 g) or female (5.74±0.13 g) offspring from reduced uterine perfusion pressure dams. In addition, 'n7AAc' treatment did not affect the birthweight of sham male (5.83±0.11 g) or female (5.64±0.12) offspring compared with vehicle sham male (5.811±0.15 g) or female (5.40±0.24 g) offspring. At adulthood, mean arterial pressure was unchanged in 'n7AAc' treated-male (133±2 mm Hg) and female (127±3 mm Hg) offspring from reduced uterine perfusion pressure dams compared with vehicle male (142±3 mm Hg) and female (133±5 mm Hg) offspring from reduced uterine perfusion pressure dams, the 'n7AAc'-treated sham male (133±3 mm Hg) and female (135±3 mm Hg) offspring, and vehicle sham male (138±4 mm Hg) and female (130±5 mm Hg) offspring. The circulating angiotensin II type 1 receptor autoantibodies were increased in vehicle male (10±2 ΔBPM) and female (14±2 ΔBPM) offspring from reduced uterine perfusion pressure dams and 'n7AAc'-treated male (11±2 ΔBPM) and female (11±2 ΔBPM) offspring from reduced uterine perfusion pressure dams compared with vehicle sham male (1±1 ΔBPM) and female (-1±1 ΔBPM) offspring and 'n7AAc'-treated sham male (-2±2 ΔBPM) and female (-2±2 ΔBPM) offspring.

CONCLUSION

Our findings indicated that perinatal 7-amino acid sequence peptide treatment does not negatively impact offspring survival or weight at birth. Perinatal 'n7AAc' treatment did not prevent increased cardiovascular risk in offspring, but it also did not cause an increased cardiovascular risk in offspring with reduced uterine perfusion pressure compared with controls. Furthermore, perinatal 'n7AAc' treatment did not affect endogenous immunologic programming as observed by no change in circulating angiotensin II type 1 receptor autoantibodies in either sex of adult offspring from reduced uterine perfusion pressure dams.

The impact of intrauterine growth restriction and prematurity on nephron endowment

In humans born at term, maximal nephron number is reached by the time nephrogenesis is completed - at approximately 36 weeks' gestation. The number of nephrons does not increase further and subsequently remains stable until loss occurs through ageing or disease. Nephron endowment is key to the functional capacity of the kidney and its resilience to disease; hence, any processes that impair kidney development in the developing fetus can have lifelong adverse consequences for renal health and, consequently, for quality and length of life. The timing of nephrogenesis underlies the vulnerability of developing human kidneys to adverse early life exposures. Indeed, exposure of the developing fetus to a suboptimal intrauterine environment during gestation - resulting in intrauterine growth restriction (IUGR) - and/or preterm birth can impede kidney development and lead to reduced nephron endowment. Furthermore, emerging research suggests that IUGR and/or preterm birth is associated with an elevated risk of chronic kidney disease in later life. The available data highlight the important role of early life development in the aetiology of kidney disease and emphasize the need to develop strategies to optimize nephron endowment in IUGR and preterm infants.

Sensitization of Hypertension: The Impact of Earlier Life Challenges: Excellence Award for Hypertension Research 2021

Hypertension affects over 1 billion individuals worldwide. Because the cause of hypertension is known only in a small fraction of patients, most individuals with high blood pressure are diagnosed as having essential hypertension. Elevated sympathetic nervous system activity has been identified in a large portion of hypertensive patients. However, the root cause for this sympathetic overdrive is unknown. A more complete understanding of the breadth of the functional capabilities of the sympathetic nervous system may lead to new insights into the cause of essential hypertension. By employing a unique experimental paradigm, we have recently discovered that the neural network controlling sympathetic drive is more reactive after rats are exposed to mild challenges (stressors) and that the hypertensive response can be sensitized (ie, hypertensive response sensitization [HTRS]). We have also found that the induction of HTRS involves plasticity in the neural network controlling sympathetic drive. The induction and maintenance of the latent HTRS state also require the functional integrity of the brain renin-angiotensin-aldosterone system and the presence of several central inflammatory factors. In this review, we will discuss the induction and expression of HTRS in adult animals and in the progeny of mothers with prenatal obesity/overnutrition or with maternal gestational hypertension. Also, interventions that reverse the effects of stressor-induced HTRS will be reviewed. Understanding the mechanisms underlying HTRS and identifying the beneficial effects of maternal or offspring early-life interventions that prevent or reverse the sensitized state can provide insights into therapeutic strategies for interrupting the vicious cycle of transgenerational hypertension.

Protection by -Biotics against Hypertension Programmed by Maternal High Fructose Diet: Rectification of Dysregulated Expression of Short-Chain Fatty Acid Receptors in the Hypothalamic Paraventricular Nucleus of Adult Offspring

The role of short-chain fatty acids (SCFAs) in the brain on the developmental programming of hypertension is poorly understood. The present study explored dysregulated tissue levels of SCFAs and expression of SCFA-sensing receptors in the hypothalamic paraventricular nucleus (PVN), a key forebrain region engaged in neural regulation of blood pressure of offspring to maternal high fructose diet (HFD) exposure. We further investigated the engagement of SCFA-sensing receptors in PVN in the beneficial effects of -biotics (prebiotic, probiotic, synbiotic, and postbiotic) on programmed hypertension. Maternal HFD during gestation and lactation significantly reduced circulating butyrate, along with decreased tissue level of butyrate and increased expression of SCFA-sensing receptors, GPR41 and olfr78, and tissue oxidative stress and neuroinflammation in PVN of HFD offspring that were rectified by oral supplement with -biotics. Gene silencing of GPR41 or olfr78 mRNA in PVN also protected adult HFD offspring from programmed hypertension and alleviated the induced oxidative stress and inflammation in PVN. In addition, oral supplement with postbiotic butyrate restored tissue butyrate levels, rectified expressions of GPR41 and olfr78 in PVN, and protected against programmed hypertension in adult HFD offspring. These data suggest that alterations in tissue butyrate level, expression of GPR41 and olfr78, and activation of SCFA-sensing receptor-dependent tissue oxidative stress and neuroinflammation in PVN could be novel mechanisms that underlie hypertension programmed by maternal HFD exposure in adult offspring. Furthermore, oral -biotics supplementation may exert beneficial effects on hypertension of developmental origin by targeting dysfunctional SCFA-sensing receptors in PVN to exert antioxidant and anti-inflammatory actions in the brain.

Oxidative Stress-Induced Hypertension of Developmental Origins: Preventive Aspects of Antioxidant Therapy

Hypertension remains the leading cause of disease burden worldwide. Hypertension can originate in the early stages of life. A growing body of evidence suggests that oxidative stress, which is characterized as a reactive oxygen species (ROS)/nitric oxide (NO) disequilibrium, has a pivotal role in the hypertension of developmental origins. Results from animal studies support the idea that early-life oxidative stress causes developmental programming in prime blood pressure (BP)-controlled organs such as the brain, kidneys, heart, and blood vessels, leading to hypertension in adult offspring. Conversely, perinatal use of antioxidants can counteract oxidative stress and therefore lower BP. This review discusses the interaction between oxidative stress and developmental programming in hypertension. It will also discuss evidence from animal models, how oxidative stress connects with other core mechanisms, and the potential of antioxidant therapy as a novel preventive strategy to prevent the hypertension of developmental origins.

Loss of the Protective Effect of Estrogen Contributes to Maternal Gestational Hypertension-Induced Hypertensive Response Sensitization Elicited by Postweaning High-Fat Diet in Female Offspring

Background

A recent study conducted in male offspring demonstrated that maternal gestational hypertension (MHT) induces hypertensive response sensitization (HTRS) elicited by postweaning high‐fat diet (HFD). In this study, we investigated the sensitizing effect of MHT on postweaning HFD‐induced hypertensive response in female rat offspring and assessed the protective role of estrogen in HTRS.

Methods and Results

The results showed that MHT also induced a sensitized HFD‐elicited hypertensive response in intact female offspring. However, compared with male offspring, this MHT‐induced HTRS was sex specific in that intact female offspring exhibited an attenuated increase in blood pressure. Ovariectomy significantly enhanced the HFD‐induced increase in blood pressure and the pressor response to centrally administered angiotensin II or tumor necrosis factor‐α in offspring of normotensive dams, which was accompanied by elevated centrally driven sympathetic activity, upregulated mRNA expression of prohypertensive components, and downregulated expression of antihypertensive components in the hypothalamic paraventricular nucleus. However, when compared with HFD‐fed ovariectomized offspring of normotensive dams, the MHT‐induced HTRS and pressor responses to centrally administered angiotensin II or tumor necrosis factor‐α in HFD‐fed intact offspring of MHT dams were not potentiated by ovariectomy, but the blood pressure and elicited pressor responses as well as central sympathetic tone remained higher.

Conclusions

The results indicate that in adult female offspring MHT induced HTRS elicited by HFD. Estrogen normally plays a protective role in antagonizing HFD prohypertensive effects, and MHT compromises this normal protective action of estrogen by augmenting brain reactivity and centrally driven sympathetic activity.

Fetal Undernutrition Programming, Sympathetic Nerve Activity, and Arterial Hypertension Development

A wealth of evidence showed that low birth weight is associated with environmental disruption during gestation, triggering embryotic or fetal adaptations and increasing the susceptibility of progeny to non-communicable diseases, including metabolic and cardiovascular diseases, obesity, and arterial hypertension. In addition, dietary disturbance during pregnancy in animal models has highlighted mechanisms that involve the genesis of arterial hypertension, particularly severe maternal low-protein intake (LP). Functional studies demonstrated that maternal low-protein intake leads to the renal decrease of sodium excretion and the dysfunction of the renin-angiotensin-aldosterone system signaling of LP offspring. The antinatriuretic effect is accentuated by a reduced number of nephron units and glomerulosclerosis, which are critical in establishing arterial hypertension phenotype. Also, in this way, studies have shown that the overactivity of the central and peripheral sympathetic nervous system occurs due to reduced sensory (afferent) renal nerve activity. As a result of this reciprocal and abnormal renorenal reflex, there is an enhanced tubule sodium proximal sodium reabsorption, which, at least in part, contributes directly to arterial hypertension development in some of the programmed models. A recent study has observed that significant changes in adrenal medulla secretion could be involved in the pathophysiological process of increasing blood pressure. Thus, this review aims to compile studies that link the central and peripheral sympathetic system activity mechanisms on water and salt handle and blood pressure control in the maternal protein-restricted offspring. Besides, these pathophysiological mechanisms mainly may involve the modulation of neurokinins and catecholamines pathways.

Maternal Angiotensin II-Induced Hypertension Sensitizes Postweaning High-Fat Diet-Elicited Hypertensive Response Through Increased Brain Reactivity in Rat Offspring

Background

Prenatal and postnatal insults can induce a physiological state that leaves offspring later in life vulnerable to subsequent challenges (stressors) eliciting cardiometabolic diseases including hypertension. In this study, we investigated whether maternal angiotensin II–induced hypertension in rats sensitizes postweaning high‐fat diet (HFD)‐elicited hypertensive response and whether this is associated with autonomic dysfunction and altered central mechanisms controlling sympathetic tone in offspring.

Methods and Results

When eating a low‐lard‐fat diet, basal mean arterial pressure of male offspring of normotensive or hypertensive dams were comparable. However, HFD feeding significantly increased mean arterial pressure in offspring of normotensive and hypertensive dams, but the elevated mean arterial pressure induced by HFD was greater in offspring of hypertensive dams, which was accompanied by greater sympathetic tone and enhanced pressor responses to centrally administrated angiotensin II or leptin. HFD feeding also produced comparable elevations in cardiac sympathetic activity and plasma levels of angiotensin II, interleukin‐6, and leptin in offspring of normotensive and hypertensive dams. Reverse transcriptase polymerase chain reaction analyses in key forebrain regions implicated in the control of sympathetic tone and blood pressure indicated that HFD feeding led to greater increases in mRNA expression of leptin, several components of the renin‐angiotensin system and proinflammatory cytokines in offspring of hypertensive dams when compared with offspring of normotensive dams.

Conclusions

The results indicate that maternal hypertension sensitized male adult offspring to HFD‐induced hypertension. Increased expression of renin‐angiotensin system components and proinflammatory cytokines, elevated brain reactivity to pressor stimuli, and augmented sympathetic drive to the cardiovascular system likely contributed.

Kidney and epigenetic mechanisms of salt-sensitive hypertension

Dietary salt intake increases blood pressure (BP) but the salt sensitivity of BP differs between individuals. The interplay of ageing, genetics and environmental factors, including malnutrition and stress, contributes to BP salt sensitivity. In adults, obesity is often associated with salt-sensitive hypertension. The children of women who experience malnutrition during pregnancy are at increased risk of developing obesity, diabetes and salt-sensitive hypertension as adults. Similarly, the offspring of mice that are fed a low-protein diet during pregnancy develop salt-sensitive hypertension in association with aberrant DNA methylation of the gene encoding type 1A angiotensin II receptor (AT_1AR) in the hypothalamus, leading to upregulation of hypothalamic AT_1AR and renal sympathetic overactivity. Ageing is also associated with salt-sensitive hypertension. In aged mice, promoter methylation leads to reduced kidney production of the anti-ageing factor Klotho and a decrease in circulating soluble Klotho. In the setting of Klotho deficiency, salt-induced activation of the vascular Wnt5a-RhoA pathway leads to ageing-associated salt-sensitive hypertension, potentially as a result of reduced renal blood flow and increased peripheral resistance. Thus, kidney mechanisms and aberrant DNA methylation of certain genes are involved in the development of salt-sensitive hypertension during fetal development and old age. Three distinct paradigms of epigenetic memory operate on different timescales in prenatal malnutrition, obesity and ageing.

Prenatal Testosterone Associates With Blood Pressure in Young Adults: A Prospective Cohort Study

[Figure: see text].

Sympathetic activation of splenic T-lymphocytes in hypertension of adult offspring programmed by maternal high fructose exposure

Whereas neuroimmune crosstalk between the sympathetic nervous system (SNS) and immune cells in the pathophysiology of hypertension is recognized, the exact effect of SNS on T-lymphocyte in hypertension remains controversial. This study assessed the hypothesis that excitation of the SNS activates splenic T-lymphocytes through redox signaling, leading to the production of pro-inflammatory cytokines and the development of hypertension. Status of T-lymphocyte activation, reactive oxygen species (ROS) production and pro-inflammatory cytokines expression in the spleen were examined in a rodent model of hypertension programmed by maternal high fructose diet (HFD) exposure. Maternal HFD exposure enhanced SNS activity and activated both CD4⁺ and CD8⁺ T-lymphocytes in the spleen of young offspring, compared to age-matched offspring exposed to maternal normal diet (ND). Maternal HFD exposure also induced tissue oxidative stress and expression of pro-inflammatory cytokines in the spleen of HFD offspring. All those cellular and molecular events were ameliorated following splenic nerve denervation (SND) by thermoablation. In contrast, activation of splenic sympathetic nerve by nicotine treatment resulted in the enhancement of tissue ROS level and activation of CD4⁺ and CD8⁺ T-cells in the spleen of ND offspring; these molecular events were attenuated by treatment with a ROS scavenger, tempol. Finally, the increase in systolic blood pressure (SBP) programmed in adult offspring by maternal HFD exposure was diminished by SND, whereas activation of splenic sympathetic nerve increased basal SBP in young ND offspring. These findings suggest that excitation of the SNS may activate splenic T-lymphocytes, leading to hypertension programming in adult offspring induced by maternal HFD exposure. Moreover, tissue oxidative stress induced by the splenic sympathetic overactivation may serve as a mediator that couples the neuroimmune crosstalk to prime programmed hypertension in HFD offspring.

Hypertension Programmed in Adult Hens by Isolated Effects of Developmental Hypoxia In Ovo

In mammals, pregnancy complicated by chronic hypoxia can program hypertension in the adult offspring. However, mechanisms remain uncertain because the partial contributions of the challenge on the placenta, mother, and fetus are difficult to disentangle. Here, we used chronic hypoxia in the chicken embryo-an established model system that permits isolation of the direct effects of developmental hypoxia on the cardiovascular system of the offspring, independent of additional effects on the mother or the placenta. Fertilized chicken eggs were exposed to normoxia (N; 21% O₂) or hypoxia (H; 13.5%-14% O₂) from the start of incubation (day 0) until day 19 (hatching, ≈day 21). Following hatching, all birds were maintained under normoxic conditions until ≈6 months of adulthood. Hypoxic incubation increased hematocrit (+27%) in the chicken embryo and induced asymmetrical growth restriction (body weight, -8.6%; biparietal diameter/body weight ratio, +7.5%) in the hatchlings (all P<0.05). At adulthood (181±4 days), chickens from hypoxic incubations remained smaller (body weight, -7.5%) and showed reduced basal and stimulated in vivo NO bioavailability (pressor response to NG-nitro-L-arginine methyl ester, -43%; phenylephrine pressor response during NO blockade, -61%) with significant hypertension (mean arterial blood pressure, +18%), increased cardiac work (ejection fraction, +12%; fractional shortening, +25%; enhanced baroreflex gain, +456%), and left ventricular wall thickening (left ventricular wall volume, +36%; all P<0.05). Therefore, we show that chronic hypoxia can act directly on a developing embryo to program hypertension, cardiovascular dysfunction, and cardiac wall remodeling in adulthood in the absence of any maternal or placental effects.

Anomalous AMPK-regulated angiotensin AT1R expression and SIRT1-mediated mitochondrial biogenesis at RVLM in hypertension programming of offspring to maternal high fructose exposure

BACKGROUND

Tissue oxidative stress, sympathetic activation and nutrient sensing signals are closely related to adult hypertension of fetal origin, although their interactions in hypertension programming remain unclear. Based on a maternal high-fructose diet (HFD) model of programmed hypertension, we tested the hypothesis that dysfunction of AMP-activated protein kinase (AMPK)-regulated angiotensin type 1 receptor (AT1R) expression and sirtuin1 (SIRT1)-dependent mitochondrial biogenesis contribute to tissue oxidative stress and sympathoexcitation in programmed hypertension of young offspring.

METHODS

Pregnant female rats were randomly assigned to receive normal diet (ND) or HFD (60% fructose) chow during pregnancy and lactation. Both ND and HFD offspring returned to ND chow after weaning, and blood pressure (BP) was monitored from age 6 to 12 weeks. At age of 8 weeks, ND and HFD offspring received oral administration of simvastatin or metformin; or brain microinfusion of losartan. BP was monitored under conscious condition by the tail-cuff method. Nutrient sensing molecules, AT1R, subunits of NADPH oxidase, mitochondrial biogenesis markers in rostral ventrolateral medulla (RVLM) were measured by Western blot analyses. RVLM oxidative stress was measured by fluorescent probe dihydroethidium and lipid peroxidation by malondialdehyde assay. Mitochondrial DNA copy number was determined by quantitative real-time polymerase chain reaction.

RESULTS

Increased systolic BP, plasma norepinephrine level and sympathetic vasomotor activity were exhibited by young HFD offspring. Reactive oxygen species (ROS) level was also elevated in RVLM where sympathetic premotor neurons reside, alongside augmented protein expressions of AT1R and pg91phox subunit of NADPH oxidase, decrease in superoxide dismutase 2; and suppression of transcription factors for mitochondrial biogenesis, peroxisome proliferator-activated receptor γ co-activator α (PGC-1α) and mitochondrial transcription factor A (TFAM). Maternal HFD also attenuated AMPK phosphorylation and protein expression of SIRT1 in RVLM of young offspring. Oral administration of a HMG-CoA reductase inhibitor, simvastatin, or an AMPK activator, metformin, to young HFD offspring reversed maternal HFD-programmed increase in AT1R and decreases in SIRT1, PGC-1α and TFAM; alleviated ROS production in RVLM, and attenuated sympathoexcitation and hypertension.

CONCLUSION

Dysfunction of AMPK-regulated AT1R expression and SIRT1-mediated mitochondrial biogenesis may contribute to tissue oxidative stress in RVLM, which in turn primes increases of sympathetic vasomotor activity and BP in young offspring programmed by excessive maternal fructose consumption.

Maternal Treatment With Captopril Persistently Alters Gut-Brain Communication and Attenuates Hypertension of Male Offspring

Maternal-fetal crosstalk has been implicated in long-term control of the health of offspring, including transgenerational hypertension. However, current knowledge is limited regarding maternal influences on the gut and its microbiome in blood pressure control in offspring. Therefore, the current study was designed to test the hypothesis that maternal factors influence the gut-brain axis impacting hypertension in offspring. We elected to use captopril, an antihypertensive angiotensin-converting enzyme inhibitor that possesses antibacterial properties, for the study. Pregnant female spontaneously hypertensive rats and normotensive Wistar Kyoto rats were treated with captopril water (100 mg/[kg·day]) or sterile water throughout pregnancy and lactation. At weaning, the pups from dams drinking sterile water were continued with sterile water until 12 weeks of age. The male pups from dams drinking captopril water were divided at weaning into 2 groups: offspring drinking captopril water and offspring withdrawn from captopril water, then drinking sterile water until 12 weeks of age. Captopril changed gut microbiota of spontaneously hypertensive rat dams, and some of these changes were reflected in their 12-week-old male offspring. These 12-week-old spontaneously hypertensive rat male offspring exposed to captopril via dams demonstrated persistently decreased systolic blood pressure, decreased number of activated microglia and neuroinflammation, as well as improvement of gut inflammation and permeability. Therefore, maternal captopril treatment improves the dysregulated gut-brain axis in spontaneously hypertensive rat male offspring, providing conceptual support that targeting the gut-brain axis via the mother may be a viable strategy for control of hypertension in the offspring.

Sodium Thiosulfate in the Pregnant Dahl Salt-Sensitive Rat, a Model of Preeclampsia

Aberrant production of hydrogen sulfide (H₂S) has been linked to preeclampsia. We hypothesized that sodium thiosulfate (STS), a H₂S donor, reduces hypertension and proteinuria, and diminishes fetal growth restriction in the Dahl salt-sensitive (S) rat, a spontaneous model of superimposed preeclampsia. In addition to a control group (n = 13), two groups received STS via drinking water at a dose of 2 g (n = 9) or 3 g per kg body weight per day (n = 8) from gestational day (GD) 10 to 20. Uterine artery resistance index was measured (GD18), urinary protein excretion rate was determined (GD19), and blood pressure and fetal outcomes were evaluated (GD20). At 2 g, STS had no effect on preeclamptic symptoms or fetal outcome. At 3 g, STS reduced maternal hypertension (121.8 ± 3.0 vs. 136.3 ± 2.9), but increased proteinuria (89 ± 15 vs. 56 ± 5 mg/24h), and relative kidney weight (0.86 ± 0.04 vs. 0.73 ± 0.02%). Fetal/placental weight ratio was reduced (3.83 ± 0.07 vs. 4.31 ± 0.08) without affecting litter size. No differences in uterine artery flow or renal histological damage were noted across treatment groups. While these data suggest a promising antihypertensive effect that could imply prolongation of preeclamptic pregnancies, the unfavorable effects on proteinuria, kidney weight, and fetal/placental weight ratio implies that clinical implementation of STS is contra-indicated until safety for mother and child can be verified.

Paternal diet impairs F1 and F2 offspring vascular function through sperm and seminal plasma specific mechanisms in mice

KEY POINTS

A low protein diet had minimal effects on paternal cardiovascular function or renin-angiotensin system activity. Paternal low protein diet modified F1 neonatal and adult offspring renin-angiotensin system activity and cardiovascular function in a sperm and/or seminal plasma specific manner. Paternal low protein diet modified F1 male offspring testicular expression of central epigenetic regulators. Significant changes in F2 neonatal offspring growth and tissue angiotensin-converting enzyme activity were programmed by paternal low protein diet in a sperm and/or seminal plasma specific manner.

ABSTRACT

Although the impact of maternal diet on adult offspring health is well characterized, the role that a father's diet has on his offspring's health remains poorly defined. We establish the significance of a sup-optimal paternal low protein diet for offspring vascular homeostasis and define the sperm and seminal plasma specific programming effects on cardiovascular health. Male C57BL6 mice were fed either a control normal protein diet (NPD; 18% protein) or an isocaloric low protein diet (LPD; 9% protein) for a minimum of 7 weeks. Using artificial insemination, in combination with vasectomized male mating, we generated offspring derived from either NPD or LPD sperm (devoid of seminal plasma) but in the presence of NPD or LPD seminal plasma (devoid of sperm). We observed that either LPD sperm or seminal fluid at conception impaired adult offspring vascular function in response to both vasoconstrictors and dilators. Underlying these changes in vascular function were significant changes in serum, lung and kidney angiotensin-converting enzyme (ACE) activity, established in F1 offspring from 3 weeks of age, maintained into adulthood and present also within juvenile F2 offspring. Furthermore, we observed differential expression of multiple central renin-angiotensin system regulators in adult offspring kidneys. Finally, paternal diet modified the expression profiles of central epigenetic regulators of DNA methylation, histone modifications and RNA methylation in adult F1 male testes. These novel data reveal the impact of sub-optimal paternal nutrition on offspring cardiovascular well-being, programming offspring cardiovascular function through both sperm and seminal plasma specific mechanisms over successive generations.

Impact of early life AT1 blockade on adult cardiac morpho-functional changes and the renin-angiotensin system in a model of neonatal high oxygen-induced cardiomyopathy

We previously reported that neonatal blockade of angiotensin II AT₁ receptor prevents cardiac changes in 4 weeks rats with neonatal hyperoxia-induced cardiomyopathy, a recognized model of prematurity-related deleterious conditions. Considering the importance of AT₁ receptor and the renin angiotensin system (RAS) in normal development, the present study aimed to investigate the adult effects of neonatal AT₁ blockade on left ventricle (LV) in rats exposed to neonatal hyperoxia. Sprague-Dawley pups were exposed to 80% O₂ or room air from days 3-10. AT₁ blocker (losartan) or H₂O were given by gavage from day 8-10. LV function (echo and intraventricular pressure), histology and expression of RAS components were examined in 15-16 weeks old adult males. Losartan treatment prevented myocardial fibrosis, LV wall thickening and stroke volume reduction in rats exposed to high O₂ in the neonatal period. However, Losartan treatment of O₂-exposed pups led to reduced ejection fraction (EF) and fractional shortening (FS), and did not prevent changes in diastolic function. Losartan also did not prevent increased LV AT₂ and decreased angiotensin-(1-7) Mas receptors expression observed in high O₂-exposed rats. Neonatal Losartan attenuated long-term impact of neonatal hyperoxia but also led to decreased EF and FS. Increased AT₂ and decreased Mas receptor expression observed in O₂-exposed group were unaffected by Losartan treatment. Our results show that early life Losartan treatment aimed at preventing cardiac consequences of neonatal deleterious conditions may also comprise detrimental effects that require further investigation prior to clinical translation in developing children.

Low Birth Weight, Blood Pressure and Renal Susceptibility

PURPOSE OF THE REVIEW

The purpose of this review is to highlight the clinical significance of increased renal risk that has its origins in fetal life. This review will also discuss the critical need to identify therapeutic interventions for use in a pregnancy complicated by placental dysfunction and intrauterine growth restriction that can mitigate the developmental origins of kidney disease without inflicting additional harm on the developing fetus.

RECENT FINDINGS

A reduction in nephron number is a contributory factor in the pathogenesis of hypertension and kidney disease in low birth weight individuals. Reduced nephron number may heighten susceptibility to a secondary renal insult, and recent studies suggest that perinatal history including birth weight should be considered in the assessment of renal risk in kidney donors. This review highlights current findings related to placental dysfunction, intrauterine growth restriction, increased risk for renal injury and disease, and potential therapeutic interventions.

Fetal Programming and Sexual Dimorphism of Mitochondrial Protein Expression and Activity of Hearts of Prenatally Hypoxic Guinea Pig Offspring

Chronic intrauterine hypoxia is a programming stimulus of cardiovascular dysfunction. While the fetal heart adapts to the reduced oxygenation, the offspring heart becomes vulnerable to subsequent metabolic challenges as an adult. Cardiac mitochondria are key organelles responsible for an efficient energy supply but are subject to damage under hypoxic conditions. We propose that intrauterine hypoxia alters mitochondrial function as an underlying programming mechanism of contractile dysfunction in the offspring. Indices of mitochondrial function such as mitochondrial DNA content, Complex (C) I-V expression, and CI/CIV enzyme activity were measured in hearts of male and female offspring at 90 days old exposed to prenatal hypoxia (10.5% O2) for 14 d prior to term (65 d). Both left ventricular tissue and cardiomyocytes exhibited decreased mitochondrial DNA content, expression of CIV, and CI/CIV activity in male hearts. In female cardiomyocytes, hypoxia had no effect on protein expression of CI-CV nor on CI/CIV activity. This study suggests that chronic intrauterine hypoxia alters the intrinsic properties of select respiratory complexes as a programming mechanism of cardiac dysfunction in the offspring. Sex differences in mitochondrial function may underlie the increased vulnerability of age-matched males compared to females in cardiovascular disease and heart failure.

Declined circulating Elabela levels in patients with essential hypertension and its association with impaired vascular function: A preliminary study

Background: Elabela (ELA) is a newly identified endogenous ligand of apelin receptor (APJ) which has been confirmed to be implicated in the pathogenesis of hypertension. Previous experiments have revealed the critical role of ELA in eliciting vasodilation and lowering blood pressure. However, the role of plasma ELA levels in hypertensive patients and its relationship with vascular function have not been investigated.Method: Thirty-one patients with essential hypertension (EH) and 31 age-matched healthy subjects as controls were recruited in the study. Plasma ELA concentration and vascular function parameters including brachial artery flow-mediated dilation (FMD) and brachial-ankle pulse wave velocity (baPWV) were measured.Results: We observed remarkably lower plasma ELA concentration in hypertensive patients as compared with controls (1.29 ± 0.56 ng/ml vs. 1.79 ± 0.55 ng/ml; P = 0.001). Linear correlation analysis showed that ELA was negatively correlated with systolic blood pressure (r = -0.388, P = 0.002) and diastolic blood pressure (r = -0.321, P = 0.011) and positively correlated with FMD (r = 0.319, P = 0.011). There was no statistically significant relationship between ELA and baPWV (r = 0.234, P = 0.067). Stepwise multiple linear analysis also identified a close association of plasma ELA levels with endothelial function.Conclusion: The present study demonstrates for the first time that circulating ELA levels are reduced in patients with EH. The fall in endogenous ELA levels may be involved in the pathogenesis of hypertension-related vascular damage.

Hypertensive disorders during pregnancy and elevated blood pressure in the offspring: A systematical review and meta-analysis protocol

BACKGROUND

Hypertensive disorders during pregnancy (HDP), including gestational hypertension, preeclampsia (PE), and chronic hypertension, affect approximately 10% of pregnancies worldwide. PE was associated with elevated blood pressure (BP) in the offspring confirmed by previous literature. No previous systematic review has investigated the associations between the subtypes of HDP and BP in offspring. Therefore, from the published literature, the present systematic review and meta-analysis aims to reach to a clear consensus on this topic.

METHODS

The Cochrane Handbook for Systematic Reviews of Interventions was used to structure our methodological approach, and the Preferred Reporting Items for Systematic Reviews and Meta Analyses Protocols guidelines to this protocol. We will include cohort, case-control, and cross-sectional studies, in which HDP or its subtypes were reported and BP in the offspring was the outcome of interest. A systematic search of PubMed, Embase, the Cochrane library, and Web of Science will be conducted according to a specific search strategy. The titles and abstracts of all literature will be reviewed independently by 2 authors. A standardized data collection form will be used for data extraction. The overall pooled estimates will be calculated by meta-analysis in Revman 5.3 based on an inverse variance method. According to the heterogeneity by the I, a random-effect model or a fixed-effect model will be chosen to pool data. Risk of bias and quality of the studies will be assessed by a suitable bias classification tool.

RESULTS

This study will provide high-quality evidence of the effects in offspring BP, which were influenced by different subtypes of HDP.

CONCLUSION

This systematic review will infer a conclusion on the associations between different subtypes of HDP and BP in offspring.

ETHICS AND DISSEMINATION

Due to the data come from the published study, the present systematic review and meta-analysis does not require ethics approval. Findings will be published in a peer-reviewed journal.

REGISTRATION

Supporting data can be found at the International Prospective Register of Systematic Reviews (PROSPERO) website, with registration number CRD 42018110872.

Effect of intracerebroventricular epinephrine microinjection on blood pressure and urinary sodium handling in gestational protein-restricted male adult rat offspring

In this study, we hypothesized that blunting of the natriuresis response to intracerebroventricularly (ICV) microinjected adrenergic agonists is involved in the development of hypertension in maternal low-protein intake (LP) offspring. A stainless steel cannula was stereotaxically implanted into the right lateral ventricle (LV), then we evaluated the ICV administration of adrenergic agonists at increasing concentrations, and of α1 and α2-adrenoceptor antagonists on blood pressure and urinary sodium handling in LP offspring relative to an age-matched normal-protein intake (NP) group. We confirmed that epinephrine (Epi) microinjected into the LV of conscious NP rats leads to enhanced natriuresis followed by a reduction in arterial pressure. This response is associated with increased proximal and post-proximal sodium excretion accompanied by an unchanged glomerular filtration rate. The current study showed, in both NP and LP offspring, that the natriuretic effect of Epi injection into the LV was abolished by prior local microinjection of an α1-adrenoceptor antagonist (prazosin). Conversely, LV α2-adrenoceptor antagonist (yohimbine) administration potentiated the action of Epi. The LV yohimbine pretreatment normalized urinary sodium excretion and reduced the blood pressure in LP compared with age-matched NP offspring. These are, as far as we are aware, the first results showing the role of central adrenergic receptors’ interaction on hypertension pathogenesis in maternal LP fetal-programming offspring. This study also provides good evidence for the existence of central nervous system adrenergic mechanisms consisting of α1 and α2-adrenoceptors, which work reciprocally on the control of renal sodium excretion and blood pressure. Although the precise mechanism of the different natriuretic response of NP and LP rats is still uncertain, these results lead us to speculate that inappropriate neural adrenergic pathways might have significant effects on tubule sodium transport, resulting in the inability of the kidneys to control hydrosaline balance and, consequently, an increase in blood pressure.

Summary: We evaluated the effect of intracerebroventricular microinjections of adrenergic agonists at increasing concentrations, and μ1 and μ2-adrenergic receptors antagonists on blood pressure and urinary sodium in hypertensive low- and normal-protein rat offdpring.

The Placental Transcriptome in Late Gestational Hypoxia Resulting in Murine Intrauterine Growth Restriction Parallels Increased Risk of Adult Cardiometabolic Disease

Intrauterine growth restriction (IUGR) enhances risk for adult onset cardiovascular disease (CVD). The mechanisms underlying IUGR are poorly understood, though inadequate blood flow and oxygen/nutrient provision are considered common endpoints. Based on evidence in humans linking IUGR to adult CVD, we hypothesized that in murine pregnancy, maternal late gestational hypoxia (LG-H) exposure resulting in IUGR would result in (1) placental transcriptome changes linked to risk for later CVD, and 2) adult phenotypes of CVD in the IUGR offspring. After subjecting pregnant mice to hypoxia (10.5% oxygen) from gestational day (GD) 14.5 to 18.5, we undertook RNA sequencing from GD19 placentas. Functional analysis suggested multiple changes in structural and functional genes important for placental health and function, with maximal dysregulation involving vascular and nutrient transport pathways. Concordantly, a ~10% decrease in birthweights and ~30% decrease in litter size was observed, supportive of placental insufficiency. We also found that the LG-H IUGR offspring exhibit increased risk for CVD at 4 months of age, manifesting as hypertension, increased abdominal fat, elevated leptin and total cholesterol concentrations. In summary, this animal model of IUGR links the placental transcriptional response to the stressor of gestational hypoxia to increased risk of developing cardiometabolic disease.

Fetal programming and the angiotensin-(1-7) axis: a review of the experimental and clinical data

Hypertension is the primary risk factor for cardiovascular disease that constitutes a serious worldwide health concern and a significant healthcare burden. As the majority of hypertension has an unknown etiology, considerable research efforts in both experimental models and human cohorts has focused on the premise that alterations in the fetal and perinatal environment are key factors in the development of hypertension in children and adults. The exact mechanisms of how fetal programming events increase the risk of hypertension and cardiovascular disease are not fully elaborated; however, the focus on alterations in the biochemical components and functional aspects of the renin-angiotensin (Ang) system (RAS) has predominated, particularly activation of the Ang-converting enzyme (ACE)-Ang II-Ang type 1 receptor (AT1R) axis. The emerging view of alternative pathways within the RAS that may functionally antagonize the Ang II axis raise the possibility that programming events also target the non-classical components of the RAS as an additional mechanism contributing to the development and progression of hypertension. In the current review, we evaluate the potential role of the ACE2-Ang-(1-7)-Mas receptor (MasR) axis of the RAS in fetal programming events and cardiovascular and renal dysfunction. Specifically, the review examines the impact of fetal programming on the Ang-(1-7) axis within the circulation, kidney, and brain such that the loss of Ang-(1-7) expression or tone, contributes to the chronic dysregulation of blood pressure (BP) and cardiometabolic disease in the offspring, as well as the influence of sex on potential programming of this pathway.

Autonomic dysfunction in programmed hypertension

Hypertension is an important modifiable risk factor for cardiovascular diseases. Its high prevalence, combined with the significant morbidity and mortality associated with secondary complications, make it a major public health concern. Despite decades of research, over 95% of all cases of hypertension remain of unknown etiology, necessitating that treatments target the established symptoms and not the cause. One of the important recent advances in hypertension research is an understanding that hypertension often may have a developmental origin. A substantial body of evidence indicates that exposure to an adverse intrauterine environment during critical periods of development may predispose an individual to develop hypertension later in life. A causative mechanism has yet to be identified, but may include epigenetic modifications, and/or alterations in renal, vascular or autonomic cardiovascular functions. This review will present evidence regarding changes in autonomic activity as a possible causative pathophysiological mechanism underlying the development of programmed hypertension. In man, low birth weight is the best-known risk factor for hypertension of developmental origins, although this is a broad surrogate measure for intrauterine adversity. This review will include clinical studies across the lifespan that have investigated autonomic function in individuals with fetal growth restriction and those born preterm. A determination of whether altered autonomic function is seen in these individuals in early life is imperative, as hypertensive disorders that have their origins in utero, and that can be identified early, will open the door to risk stratification, and the development of new strategies that prevent or specifically target these mechanisms.

Prenatal therapeutics and programming of cardiovascular function

Cardiovascular diseases (CVD) are a leading cause of mortality worldwide. Despite recognizing the importance of risk factors in dictating CVD susceptibility and onset, patient treatment remains a challenging endeavor. Increasingly, the benefits of prevention and mitigation of risk factors earlier in life are being acknowledged. The developmental origins of health and disease posits that insults during specific periods of development can influence long-term health outcomes; this occurs because the developing organism is highly plastic, and hence vulnerable to environmental perturbations. By extension, targeted therapeutics instituted during critical periods of development may confer long-term protection, and thus reduce the risk of CVD in later life. This review provides a brief overview of models of developmental programming, and then discusses the impact of perinatal therapeutic interventions on long-term cardiovascular function in the offspring. The discussion focuses on bioactive food components, as well as pharmacological agents currently approved for use in pregnancy; in short, those agents most likely to be used in pregnancy and early childhood.

Prenatal hypoxia impairs cardiac mitochondrial and ventricular function in guinea pig offspring in a sex-related manner

Adverse intrauterine conditions cause fetal growth restriction and increase the risk of adult cardiovascular disease. We hypothesize that intrauterine hypoxia impairs fetal heart function, is sustained after birth, and manifests as both cardiac and mitochondrial dysfunction in offspring guinea pigs (GPs). Pregnant GPs were exposed to 10.5% O₂ (HPX) at 50 days of gestation (full term = 65 days) or normoxia (NMX) for the duration of the pregnancy. Pups were allowed to deliver vaginally and raised in a NMX environment. At 90 days of age, mean arterial pressure (MAP) was measured in anesthetized GPs. NMX and prenatally HPX offspring underwent echocardiographic imaging for in vivo measurement of left ventricular cardiac morphology and function, and O₂ consumption rates and complex IV enzyme activity were measured from isolated cardiomyocytes and mitochondria, respectively. Prenatal HPX increased ( P < 0.01) MAP (52.3 ± 1.3 and 58.4 ± 1.1 mmHg in NMX and HPX, respectively) and decreased ( P < 0.05) stroke volume (439.8 ± 54.5 and 289.4 ± 15.8 μl in NMX and HPX, respectively), cardiac output (94.4 ± 11.2 and 67.3 ± 3.8 ml/min in NMX and HPX, respectively), ejection fraction, and fractional shortening in male, but not female, GPs. HPX had no effect on left ventricular wall thickness or end-diastolic volume in either sex. HPX reduced mitochondrial maximal respiration and respiratory reserve capacity and complex IV activity rates in hearts of male, but not female, GPs. Prenatal HPX is a programming stimulus that increases MAP and decreases cardiac and mitochondrial function in male offspring. Sex-related differences in the contractile and mitochondrial responses suggest that female GPs are protected from cardiovascular programming of prenatal HPX.

Transcriptomic profile analysis of brain microvascular pericytes in spontaneously hypertensive rats by RNA-Seq

BACKGROUND

Changes in the structure and function of micro-vessels is the pathogenic basis of organ damage in cardiovascular and cerebrovascular diseases. Microcirculation is primarily affected in hypertension, resulting in increased vascular resistance. Pericytes are contractile cells that are embedded in the basement membrane of capillaries, and regulate endothelial cell membrane maturation, capillary blood flow, cell debris removal, and stability of endothelial cells. However, the exact role of brain microvascular pericytes in the pathogenesis of hypertension has not been elucidated.

METHODS

Brain microvascular pericytes were isolated from spontaneously hypertensive rats (SHR) and wild type Wistar Kyoto (WKY) rats. The transcriptomes of SHR and WKY pericytes were analyzed by RNA-Seq, and the differentially expressed genes (DEGs) were screened by Ballgown, and Student's t test was used to be used to compare differences between groups. DAVID was used for the GO-enrichment analysis and KEGG pathway analysis of the DEGs, and an interaction network between the significant signaling pathways and DEGs was constructed.

RESULTS

A total of 1356 DEGs were identified between the WKY and the SHR group pericytes (P value < 0.05, Fold change > 1.5), of which 733 were upregulated and 623 downregulated. The genes with greatest betweenness centrality values were Itgb1, Vcam-1 and MMP-9. Based on KEGG analysis, 34 interacting signaling pathways and 43 interacting genes were screened, and MAPK, p53, Wnt, Jak-STAT, TGF-beta, VEGF and PPAR signaling pathways were the key nodes.

CONCLUSIONS

Several DEGs and signaling pathways were identified in the brain microvascular pericytes of SHR rats compared to the WKY rats. Our findings will lay the foundation to study the role of brain microvascular pericytes in the development of spontaneous hypertension.

Nutritional approach to preeclampsia prevention

PURPOSE OF REVIEW

Although not fully understood, the physiopathology of preeclampsia is thought to involve an abnormal placentation, diffuse endothelial cell dysfunction and increased systemic inflammation. As micronutrients play a key role in placental endothelial function, oxidative stress and expression of angiogenic factors, periconceptional micronutrient supplementation has been proposed to reduce the risk of preeclampsia. However, recent studies reported conflicting results.

RECENT FINDINGS

Calcium intake (>1 g/day) may reduce the risk of preeclampsia in women with low-calcium diet. Data from recently updated Cochrane reviews did not support routine supplementation of vitamins C, E or D for either the prevention or treatment of preeclampsia. Evidences are also poor to support zinc or folic acid supplementation for preeclampsia prevention. Dark chocolate, flavonoid-rich food, and long-chain polyunsaturated fatty acids might also be candidates for prevention of preeclampsia.

SUMMARY

Through antioxidant, anti-inflammatory or vasoactive proprieties, micronutrients are good candidates for preeclampsia prevention. Calcium supplementation is recommended to prevent preeclampsia in women with low-calcium intake. Despite positive clinical and in-vitro data, strong evidence to support periconceptional supplementation of other micronutrients for preeclampsia risk-reduction is still lacking. Further studies are also needed to evaluate the benefit of nutritional supplementation such as chocolate and long-chain polyunsaturated fatty acids.

Perinatal α-tocopherol overload programs alterations in kidney development and renal angiotensin II signaling pathways at birth and at juvenile age: Mechanisms underlying the development of elevated blood pressure

α-Tocopherol (α-Toc) overload increases the risk of dying in humans (E.R. Miller III et al. Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality Ann Int Med. 142 (2005) 37-46), and overload during early development leads to elevation of blood pressure at adult life, but the mechanism(s) remains unknown. We hypothesized that α-Toc overload during organogenesis affects the renal renin angiotensin system (RAS) components and renal Na⁺ handling, culminating with late elevated blood pressure. Pregnant Wistar rats received α-Toc or the superoxide dismutase mimetic tempol throughout pregnancy. We evaluated components of the intrarenal renin angiotensin system in neonate and juvenile offspring: Ang II-positive cells, Ang II receptors (AT₁ and AT₂), linked protein kinases, O₂^- production, NADPH oxidase abundance, lipid peroxidation and activity of Na⁺-transporting ATPases. In juvenile offspring we followed the evolution of arterial blood pressure. Neonates from α-Toc and tempol mothers presented with accentuated retardment in tubular development, pronounced decrease in glomerular Ang II-positive cells and AT₁/AT₂ ratio, intense production of O₂^- and upregulation of the α, ε and λ PKC isoforms. α-Toc decreased or augmented the abundance of renal (Na⁺+K⁺)ATPase depending on the age and α-Toc dose. In juvenile rats the number of Ang II-positive cells returned to control values as well as PKCα, but co-existing with marked upregulation in the activity of (Na⁺+K⁺) and Na⁺-ATPase and elevated arterial pressure at 30 days. We conclude that the mechanisms of these alterations rely on selective targeting of renal RAS components through genic and pro-oxidant effects of the vitamin.

Sex differences in maternal gestational hypertension-induced sensitization of angiotensin II hypertension in rat offspring: the protective effect of estrogen

Recent studies demonstrate that maternal hypertension during pregnancy sensitizes an angiotensin (ANG) II-induced increase in blood pressure (BP) in adult male offspring that was associated with upregulation of mRNA expression of several renin-angiotensin-aldosterone system (RAAS) components and NADPH oxidase in the lamina terminalis (LT) and paraventricular nucleus (PVN). The purpose of the present study was to test whether there are sex differences in the maternal hypertension-induced sensitization of ANG II hypertension, and whether sex hormones are involved in the sensitization process. Male offspring of hypertensive dams showed an enhanced hypertensive response to systemic ANG II when compared with male offspring of normotensive dams and to female offspring of either normotensive or hypertensive dams. Castration did not alter the hypertensive response to ANG II in male offspring. Intact female offspring had no upregulation of RAAS components and NADPH oxidase in the LT and PVN, whereas ovariectomy (OVX) upregulated mRNA expression of several RAAS components and NADPH oxidase in these nuclei and induced a greater increase in the pressor response to ANG II in female offspring of hypertensive dams compared with female offspring of normotensive dams. This enhanced increase in BP was partially attenuated by 17β-estradiol replacement in the OVX offspring of hypertensive dams. The results suggest that maternal hypertension induces a sex-specific sensitization of ANG II-induced hypertension and mRNA expression of brain RAAS and NADPH oxidase in offspring. Female offspring are protected from maternal hypertension-induced sensitization of ANG II hypertension, and female sex hormones are partially responsible for this protective effect.

Prenatal hypoxia leads to hypertension, renal renin-angiotensin system activation and exacerbates salt-induced pathology in a sex-specific manner

Prenatal hypoxia is associated with growth restriction and adverse cardiovascular outcomes. Here, we describe renal and cardiovascular outcomes in ageing mouse offspring prenatally exposed to hypoxia (12% O₂) from embryonic day 14.5 until birth. At 12 months of age, both male and female offspring exposed to prenatal hypoxia had elevated mean arterial pressure. Glomerular number was reduced by 25% in hypoxia-exposed male, but not female, offspring and this was associated with increased urinary albumin excretion, glomerular hypertrophy and renal fibrosis. Hypoxia-exposed offspring of both sexes were more susceptible to salt-induced cardiac fibrosis, however, renal fibrosis was exacerbated by high salt in males only. In male but not female hypoxia-exposed offspring, renal renin mRNA was increased at weaning. By 12 months, renal renin mRNA expression and concentrations were elevated in both sexes. mRNA expression of At_1aR was also elevated in male hypoxia-exposed offspring at 12 months. These results demonstrate that prenatal hypoxia programs elevated blood pressure and exacerbates salt-induced cardiovascular and renal pathology in a sex specific manner. Given sex differences observed in RAS expression and nephron number, future studies may consider RAS blockade as a therapeutic target in this model.

Renal sodium handling and blood pressure changes in gestational protein-restricted offspring: Role of renal nerves and ganglia neurokinin expression

Background

Considering long-term changes in renal sodium handling and blood pressure in maternal protein-restricted (LP) offspring, we assumed that the development of LP hypertension results from abnormal dorsal root ganglia (DRG) neurokinin expression associated with impaired responsiveness of renal sensory receptors, promoting a reduced urinary excretion of sodium. The present study investigates whether increased blood pressure in protein-restricted offspring would be associated with changes in the DRG cells and in renal pelvic wall expression of NK1R, SP and CGRP when compared to NP offspring. In addition, we assessed the tubular sodium handling, estimated by creatinine and lithium clearances before and after bilateral renal denervation in conscious LP offspring relative to age-matched NP counterparts.

Methods

Dams received a normal (NP) or low-protein diet (LP) during their entire pregnancy period. Male NP or LP offspring underwent bilateral surgical renal denervation before the 8-week renal functional test and blood pressure measurements. Immunofluorescence staining in DRG cells was assessed in optical sections by confocal laser scanning microscope.

Results

The current data demonstrated a sustained rise in blood pressure associated with a decrease in fractional excretion of sodium (FENa) by reducing post-proximal tubule sodium rejection in 16-wk old LP rats relative to age-matched NP counterparts. According to this study, bilateral renal denervation attenuated blood pressure and increased FENa in LP offspring. Furthermore, an immunohistochemical analysis showed a reduced expression of SP and CGRP in DRGs of LP when compared with NP rats. Renal pelvis of LP rats did not show a strong CGRP expression related to NP rats, whereas there was no change in SP immunostaining.

Conclusions

These observations raise the possibility that impaired DRG and pelvic neurokinin expression associated with responsiveness of renal sensory receptors in 16-wk old LP offspring are conducive to excess renal reabsorption of sodium and development of hypertension in this programmed model.

Assisted Reproductive Technologies Predispose to Insulin Resistance and Obesity in Male Mice Challenged With a High-Fat Diet

Assisted reproductive technology (ART) alters glucose homeostasis in mice and humans, but the underlying mechanisms are incompletely understood. ART induces endothelial dysfunction and arterial hypertension by epigenetic alteration of the endothelial nitric oxide synthase (eNOS) gene. In eNOS-deficient mice, insulin resistance is related to impaired insulin stimulation of muscle blood flow and substrate delivery and defective intrinsic skeletal muscle glucose uptake. We therefore assessed glucose tolerance, insulin sensitivity (euglycemic clamp), insulin stimulation of muscle blood flow in vivo, and muscle glucose uptake in vitro in male ART and control mice fed a normal chow (NC) or challenged with a high-fat diet (HFD) during 8 weeks. Glucose tolerance and insulin sensitivity were similar in NC-fed animals. When challenged with a HFD, however, ART mice developed exaggerated obesity, fasting hyperinsulinemia and hyperglycemia, and a 20% lower insulin-stimulated glucose utilization than did control mice (steady-state glucose infusion rate (GIR), 51.3 ± 7.3 vs 64.0 ± 10.8 mg/kg/min, P = 0.012). ART-induced insulin resistance was associated with defective insulin stimulation of muscle blood flow, whereas intrinsic skeletal muscle glucose uptake was normal. In conclusion, ART-induced endothelial dysfunction, when challenged with a metabolic stress, facilitates glucose intolerance and insulin resistance. Similar mechanisms may contribute to ART-induced alterations of the metabolic phenotype in humans.

Maternal Gestational Hypertension-Induced Sensitization of Angiotensin II Hypertension Is Reversed by Renal Denervation or Angiotensin-Converting Enzyme Inhibition in Rat Offspring

Numerous findings demonstrate that there is a strong association between maternal health during pregnancy and cardiovascular disease in adult offspring. The purpose of the present study was to test whether maternal gestational hypertension modulates brain renin-angiotensin-aldosterone system (RAAS) and proinflammatory cytokines that sensitizes angiotensin II-elicited hypertensive response in adult offspring. In addition, the role of renal nerves and the RAAS in the sensitization process was investigated. Reverse transcription polymerase chain reaction analyses of structures of the lamina terminalis and paraventricular nucleus indicated upregulation of mRNA expression of several RAAS components and proinflammatory cytokines in 10-week-old male offspring of hypertensive dams. Most of these increases were significantly inhibited by either renal denervation performed at 8 weeks of age or treatment with an angiotensin-converting enzyme inhibitor, captopril, in drinking water starting at weaning. When tested beginning at 10 weeks of age, a pressor dose of angiotensin II resulted in enhanced upregulation of mRNA expression of RAAS components and proinflammatory cytokines in the lamina terminalis and paraventricular nucleus and an augmented pressor response in male offspring of hypertensive dams. The augmented blood pressure change and most of the increases in gene expression in the offspring were abolished by either renal denervation or captopril. The results suggest that maternal hypertension during pregnancy enhances pressor responses to angiotensin II through overactivity of renal nerves and the RAAS in male offspring and that upregulation of the brain RAAS and proinflammatory cytokines in these offspring may contribute to maternal gestational hypertension-induced sensitization of the hypertensive response to angiotensin II.

Sex-Specificity of Mineralocorticoid Target Gene Expression during Renal Development, and Long-Term Consequences

Sex differences have been identified in various biological processes, including hypertension. The mineralocorticoid signaling pathway is an important contributor to early arterial hypertension, however its sex-specific expression has been scarcely studied, particularly with respect to the kidney. Basal systolic blood pressure (SBP) and heart rate (HR) were measured in adult male and female mice. Renal gene expression studies of major players of mineralocorticoid signaling were performed at different developmental stages in male and female mice using reverse transcription quantitative PCR (RT-qPCR), and were compared to those of the same genes in the lung, another mineralocorticoid epithelial target tissue that regulates ion exchange and electrolyte balance. The role of sex hormones in the regulation of these genes was also investigated in differentiated KC3AC1 renal cells. Additionally, renal expression of the 11 β-hydroxysteroid dehydrogenase type 2 (11βHSD2) protein, a regulator of mineralocorticoid specificity, was measured by immunoblotting and its activity was indirectly assessed in the plasma using liquid-chromatography coupled to mass spectrometry in tandem (LC-MSMS) method. SBP and HR were found to be significantly lower in females compared to males. This was accompanied by a sex- and tissue-specific expression profile throughout renal development of the mineralocorticoid target genes serum and glucocorticoid-regulated kinase 1 (Sgk1) and glucocorticoid-induced leucine zipper protein (Gilz), together with Hsd11b2, Finally, the implication of sex hormones in this sex-specific expression profile was demonstrated in vitro, most notably for Gilz mRNA expression. We demonstrate a tissue-specific, sex-dependent and developmentally-regulated pattern of expression of the mineralocorticoid pathway that could have important implications in physiology and pathology.