Angiotensin II-mediated vascular changes in aged offspring rats exposed to perinatal nicotine

Epigenetic upregulation of carotid body angiotensin signaling increases blood pressure

Epigenetic changes can be shaped by a wide array of environmental cues as well as maternal health and behaviors. One of the most detrimental behaviors to the developing fetus is nicotine exposure. Perinatal nicotine exposure remains a significant risk factor for cardiovascular health and in particular, hypertension. Increased basal carotid body activity and excitation are significant contributors to hypertension. This study investigated the epigenetic changes to carotid body activity induced by perinatal nicotine exposure resulting in carotid body-mediated hypertension. Using a rodent model of perinatal nicotine exposure, we show that angiotensin II type 1 receptor signaling is upregulated in the carotid bodies of nicotine-exposed offspring. These changes were attributed to an upregulation of genetic promotion as DNA methylation of AT1r and PKC occurred within intron regions, exemplifying an upregulation of genetic transcription for these genes. Nicotine increased angiotensin signaling in vitro . Carotid body reactivity to angiotensin was increased in perinatal nicotine-exposed offspring compared to control offspring. Further, carotid body denervation reduced arterial pressure as a result of suppressed efferent sympathetic activity in perinatal nicotine-exposed offspring. Our data demonstrate that perinatal nicotine exposure adversely affects carotid body afferent sensing, which augments efferent sympathetic activity to increase vasoconstrictor signaling and induce hypertension. Targeting angiotensin signaling in the carotid bodies may provide a way to alleviate hypertension acquired by adverse maternal uterine environments in general and perinatal nicotine exposure in particular.

Cardiopulmonary Impact of Electronic Cigarettes and Vaping Products: A Scientific Statement From the American Heart Association

Vaping and electronic cigarette (e-cigarette) use have grown exponentially in the past decade, particularly among youth and young adults. Cigarette smoking is a risk factor for both cardiovascular and pulmonary disease. Because of their more limited ingredients and the absence of combustion, e-cigarettes and vaping products are often touted as safer alternative and potential tobacco-cessation products. The outbreak of e-cigarette or vaping product use-associated lung injury in the United States in 2019, which led to >2800 hospitalizations, highlighted the risks of e-cigarettes and vaping products. Currently, all e-cigarettes are regulated as tobacco products and thus do not undergo the premarket animal and human safety studies required of a drug product or medical device. Because youth prevalence of e-cigarette and vaping product use was as high as 27.5% in high school students in 2019 in the United States, it is critical to assess the short-term and long-term health effects of these products, as well as the development of interventional and public health efforts to reduce youth use. The objectives of this scientific statement are (1) to describe and discuss e-cigarettes and vaping products use patterns among youth and adults; (2) to identify harmful and potentially harmful constituents in vaping aerosols; (3) to critically assess the molecular, animal, and clinical evidence on the acute and chronic cardiovascular and pulmonary risks of e-cigarette and vaping products use; (4) to describe the current evidence of e-cigarettes and vaping products as potential tobacco-cessation products; and (5) to summarize current public health and regulatory efforts of e-cigarettes and vaping products. It is timely, therefore, to review the short-term and especially the long-term implications of e-cigarettes and vaping products on cardiopulmonary health. Early molecular and clinical evidence suggests various acute physiological effects from electronic nicotine delivery systems, particularly those containing nicotine. Additional clinical and animal-exposure model research is critically needed as the use of these products continues to grow.

Cardiovascular Dysfunction in Intrauterine Growth Restriction

PURPOSE OF REVIEW

We highlight important new findings on cardiovascular dysfunction in intrauterine growth restriction.

RECENT FINDINGS

Intrauterine growth restriction (IUGR) is a multifactorial condition which negatively impacts neonatal growth during pregnancy and is associated with health problems during the lifespan. It affects 5-15% of all pregnancies in the USA and Europe with varying percentages in developing countries. Epidemiological studies have reported that IUGR is associated with the pathogenesis of hypertension, activation of the renin-angiotensin system (RAS), disruption in placental-mTORC and TGFβ signaling cascades, and endothelial dysfunction in IUGR fetuses, children, adolescents, and adults resulting in the development of cardiovascular diseases (CVD). Experimental studies are needed to investigate therapeutic measures to treat increased blood pressure (BP) and long-term CVD problems in people affected by IUGR. We outline the mechanisms mediating fetal programming of hypertension in developing CVD. We have reviewed findings from different experimental models focusing on recent studies that demonstrate CVD in IUGR.

Insights into the Mechanisms of Fetal Growth Restriction-Induced Programming of Hypertension

In recent decades, both clinical and animal studies have shown that fetal growth restriction (FGR), caused by exposure to adverse uterine environments, is a risk factor for hypertension as well as for a variety of adult diseases. This observation has shaped and informed the now widely accepted theory of developmental origins of health and disease (DOHaD). There is a plethora of evidence supporting the association of FGR with increased risk of adult hypertension; however, the underlying mechanisms responsible for this correlation remain unclear. This review aims to explain the current advances in the field of fetal programming of hypertension and a brief narration of the underlying mechanisms that may link FGR to increased risk of adult hypertension. We explain the theory of DOHaD and then provide evidence from both clinical and basic science research which support the theory of fetal programming of adult hypertension. In addition, we have explored the underlying mechanisms that may link FGR to an increased risk of adult hypertension. These mechanisms include epigenetic changes, metabolic disorders, vascular dysfunction, neurohormonal impairment, and alterations in renal physiology and function. We further describe sex differences seen in the developmental origins of hypertension and provide insights into the opportunities and challenges present in this field.

DNA Methylation-Reprogrammed Ang II (Angiotensin II) Type 1 Receptor-Early Growth Response Gene 1-Protein Kinase C ε Axis Underlies Vascular Hypercontractility in Antenatal Hypoxic Offspring

As the most common clinical stress during mid and late pregnancy, antenatal hypoxia has profound adverse effects on individual's vascular health later in life, but the underlying mechanisms are still not understood. The purpose of this study was to reveal the mechanisms of the acquired vascular dysfunction in offspring imposed by antenatal hypoxia. Pregnant rats were housed in a normoxic or hypoxic (10.5% oxygen) chamber from gestation day 10 to 21. Male offspring were euthanized at gestational day 21 (fetus) or postnatal 16 weeks old (adult offspring). Mesenteric arteries were collected for examining Ang II (angiotensin II)-mediated vascular contractility, gene expression, and promoter methylation. Antenatal hypoxia increased vascular sensitivity to Ang II, which was resulted by an upregulated AT1R (angiotensin II type 1 receptor). The increased AT1R was correlated with a hypomethylation-mediated activated transcription of Agtr1a (alpha subtype of AT1R). In addition, we presented evidences that there was an AT1R-Egr1 (early growth response gene 1)-PKCε (ε isoform of protein kinase C) axis in vasculature; AT1R could modulate PKCε expression via upregulating Egr1; Egr1 mediated transcription activation of PKCε via Egr1 binding sites in PKCε gene promoter. Overall, antenatal hypoxia activated AT1R-Egr1-PKCε axis in vasculature, eventually predisposed offspring to vascular hypercontractility. This is the first description that antenatal hypoxia resulted in vascular adverse outcomes in postnatal offspring, was strongly associated with reprogrammed gene expression via a DNA methylation-mediated epigenetic mechanism, advancing understanding toward the influence of adverse antenatal factors in early life on long-term vascular health.

Adverse effects of fetal exposure of electronic-cigarettes and high-fat diet on male neonatal hearts

Epidemiological studies have shown an increased risk of cardiovascular diseases in children born to mothers who smoked during pregnancy. The cardiovascular risk in the offspring associated with in utero nicotine exposure is further exaggerated by maternal obesity. The consumption of electronic cigarettes (e-cigarettes) is alarmingly increasing among adolescents and young adults without the knowledge of their harmful health effects. There has also been a substantial increase in e-cigarette use by women of reproductive age. This study investigates the detrimental effects of gestational exposure of e-cigarette and a high-fat diet (HFD) on neonatal hearts. Time-mated pregnant mice were fed a HFD and exposed to saline or e-cigarette aerosol with 2.4% nicotine from embryonic day 4 (E4) to E20. We demonstrated that in utero exposure of e-cigarettes and HFD from E4 to E20 triggers cardiomyocyte (CM) apoptosis in the offspring at postnatal day1 (PND1), PND3, and PND14. Induction of CM apoptosis following gestational exposure of e-cigarettes and HFD was associated with inactivation of AMP-activated protein kinase (AMPK), increased cardiac oxidative stress coupled with perturbation of cardiac BAX/ BCL-2 ratio and activation of caspase 3 at PND 14. Electron microscopy further revealed that left ventricles of pups at PND14 after e-cigarette exposure exhibited apoptotic nuclei, convoluted nuclear membranes, myofibrillar derangement, and enlarged mitochondria occasionally showing signs of crystolysis, indicative of cardiomyopathy and cardiac dysfunction. Our results show profound adverse effects of prenatal exposure of e-cigarette plus HFD in neonatal hearts that may lead to long-term adverse cardiac consequences in the adult.

Maternal high-fat diet increases vascular contractility in adult offspring in a sex-dependent manner

A maternal high-fat diet (HFD) is a risk factor for cardiovascular diseases in offspring. The aim of the study was to determine whether maternal HFD causes the epigenetic programming of vascular angiotensin II receptors (ATRs) and leads to heightened vascular contraction in adult male offspring in a sex-dependent manner. Pregnant rats were treated with HFD (60% kcal fat). Aortas were isolated from adult male and female offspring. Maternal HFD increased phenylephrine (PE)-and angiotensin II (Ang II)-induced contractions of the aorta in male but not female offspring. N^G-nitro-L-arginine (ʟ-NNA; 100 μM) abrogated the maternal HFD-induced increase in PE-mediated contraction. HFD caused a decrease in endothelium-dependent relaxations induced by acetylcholine in male but not female offspring. However, it had no effect on sodium nitroprusside-induced endothelium-independent relaxations of aortas regardless of sex. The AT₁ receptor (AT₁R) antagonist losartan (10 μM), but not the AT₂ receptor (AT₂R) antagonist PD123319 (10 μM), blocked Ang II-induced contractions in both control and HFD offspring in both sexes. Maternal HFD increased AT₁R but decreased AT₂R, leading to an increased ratio of AT₁R/AT₂R in HFD male offspring, which was associated with selective decreases in DNA methylation at the AT_1aR promoter and increases in DNA methylation at the AT₂R promoter. The vascular ratio of AT₁R/AT₂R was not significantly different in HFD female offspring compared with the control group. Our results indicated that maternal HFD caused a differential regulation of vascular AT₁R and AT₂R gene expression through a DNA methylation mechanism, which may be involved in HFD-induced vascular dysfunction and the development of a hypertensive phenotype in adulthood in a sex-dependent manner.

Angiotensin II AT2 Receptors Contribute to Regulate the Sympathoadrenal and Hormonal Reaction to Stress Stimuli

Angiotensin II, through AT1 receptor stimulation, mediates multiple cardiovascular, metabolic, and behavioral functions including the response to stressors. Conversely, the function of Angiotensin II AT2 receptors has not been totally clarified. In adult rodents, AT2 receptor distribution is very limited but it is particularly high in the adrenal medulla. Recent results strongly indicate that AT2 receptors contribute to the regulation of the response to stress stimuli. This occurs in association with AT1 receptors, both receptor types reciprocally influencing their expression and therefore their function. AT2 receptors appear to influence the response to many types of stressors and in all components of the hypothalamic-pituitary-adrenal axis. The molecular mechanisms involved in AT2 receptor activation, the complex interactions with AT1 receptors, and additional factors participating in the control of AT2 receptor regulation and activity in response to stressors are only partially understood. Further research is necessary to close this knowledge gap and to clarify whether AT2 receptor activation may carry the potential of a major translational advance.

Effects of Intrauterine Growth Restriction and Female Sex on Future Blood Pressure and Cardiovascular Disease

PURPOSE OF THE REVIEW

It is well-established that the age-related increase in blood pressure is augmented after menopause. Yet, the prevalence of hypertension is enhanced in low birth weight women relative to normal birth weight counterparts by 60 years of age suggesting that adverse influences during fetal life heighten cardiovascular risk in later life.

RECENT FINDINGS

A changing hormonal milieu may contribute to increased cardiovascular risk that occurs after the menopausal transition. Low birth weight is associated with early age at menopause. A recent study indicates that a shift towards testosterone excess following early reproductive senescence may contribute to the etiology of age-dependent increases in blood pressure in a rodent model of low birth weight. This review will highlight current findings related to postmenopausal hypertension and discuss potential mechanisms that may contribute to the enhanced cardiovascular risk that develops with age in low birth weight women.

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.

High sucrose intake during gestation increases angiotensin II type 1 receptor-mediated vascular contractility associated with epigenetic alterations in aged offspring rats

Accruing evidence have confirmed that the fetal programming in response to adverse environmental in utero factors plays essential roles in the pathogenesis of hypertension in later life. High sugar intake has been accepted worldwide in everyday life diet and becomes the critical public health issue. Our previous studies indicated that intake of high sucrose (HS) during pregnancy could change the vascular reactivity and dipsogenic behavior closely associated with abnormal renin-angiotensin system (RAS), to increase the risk of hypertension in adult offspring. In the present study, we tested the hypothesis that maternal HS intake in pregnancy may further deteriorate the Ang II-induced cardiovascular responses in the aged offspring. HS intake was provided to pregnant rats throughout the gestation. Blood pressure (BP) in conscious state and vascular contractility in vitro were measured in 22-month-old aged offspring rats. In addition, mRNA and protein expressions and epigenetic changes of Ang II type 1 receptor (AT₁R) gene in blood vessels were determined with the methods of real-time RT-PCR, Western blotting, and Chromatin Immunoprecipitation Assay (CHIP). Results showed that, in the aged offspring, maternal HS intake during gestation would cause the elevation of basal BP which could be diminished by losartan. Although the circulatory Ang II was not changed, levels of local Ang II were significantly increased in blood vessels. In addition, prenatal HS exposure would significantly enhance the AT₁R-mediated vasoconstrictions in both aorta and mesenteric arteries of the aged offspring. Moreover, in the aged offspring of prenatal HS exposure, mRNA and protein expressions of AT₁R gene in both large and small blood vessels were significantly increased, which should be closely associated with the changes of epigenetic mechanisms such as histone modifications. Collectively, we proposed that maternal HS intake during gestation would cause abnormal BP responses mediated via the enhancement of vascular RAS, together with the increased expression of AT₁R gene related to the its epigenetic changes, which would actually lead to the overt phenotype of hypertension in the aged offspring.

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.

Gender differences in developmental programming of cardiovascular diseases

Hypertension is a risk factor for cardiovascular disease, the leading cause of death worldwide. Although multiple factors contribute to the pathogenesis of hypertension, studies by Dr David Barker reporting an inverse relationship between birth weight and blood pressure led to the hypothesis that slow growth during fetal life increased blood pressure and the risk for cardiovascular disease in later life. It is now recognized that growth during infancy and childhood, in addition to exposure to adverse influences during fetal life, contributes to the developmental programming of increased cardiovascular risk. Numerous epidemiological studies support the link between influences during early life and later cardiovascular health; experimental models provide proof of principle and indicate that numerous mechanisms contribute to the developmental origins of chronic disease. Sex has an impact on the severity of cardiovascular risk in experimental models of developmental insult. Yet, few studies examine the influence of sex on blood pressure and cardiovascular health in low-birth weight men and women. Fewer still assess the impact of ageing on sex differences in programmed cardiovascular risk. Thus, the aim of the present review is to highlight current data about sex differences in the developmental programming of blood pressure and cardiovascular disease.

Protective Effect of Antenatal Antioxidant on Nicotine-Induced Heart Ischemia-Sensitive Phenotype in Rat Offspring

Fetal nicotine exposure increased risk of developing cardiovascular disease later in life. The present study tested the hypothesis that perinatal nicotine-induced programming of heart ischemia-sensitive phenotype is mediated by enhanced reactive oxygen species (ROS) in offspring. Nicotine was administered to pregnant rats via subcutaneous osmotic minipumps from day 4 of gestation to day 10 after birth, in the absence or presence of a ROS inhibitor, N-acetyl-cysteine (NAC) in drinking water. Experiments were conducted in 8 month old age male offspring. Isolated hearts were perfused in a Langendorff preparation. Perinatal nicotine treatment significantly increased ischemia and reperfusion-induced left ventricular injury, and decreased post-ischemic recovery of left ventricular function and coronary flow rate. In addition, nicotine enhanced cardiac ROS production and significantly attenuated protein kinase Cε (PKCε) protein abundance in the heart. Although nicotine had no effect on total cardiac glycogen synthase kinase-3β (GSK3β) protein expression, it significantly increased the phosphorylation of GSK3β at serine 9 residue in the heart. NAC inhibited nicotine-mediated increase in ROS production, recovered PKCε gene expression and abrogated increased phosphorylation of GSK3β. Of importance, NAC blocked perinatal nicotine-induced increase in ischemia and reperfusion injury in the heart. These findings provide novel evidence that increased oxidative stress plays a causal role in perinatal nicotine-induced developmental programming of ischemic sensitive phenotype in the heart, and suggest potential therapeutic targets of anti-oxidative stress in the treatment of ischemic heart disease.

High-salt diets during pregnancy increases renal vascular reactivity due to altered soluble guanylyl cyclase-related pathways in rat offspring

Adverse prenatal factors such as overtake of salt or fat food are potential risks for cardiovascular diseases in offspring. This study tested the hypothesis that prenatal high-salt (HS) diets may influence renal vascular tone and attenuates signaling pathways related to soluble guanylyl cyclase (sGC) or/and large-conductance Ca(2+)-activated K(+) (BKCa) channels in the offspring. Pregnant rats were fed either normal salt (NS) (1% NaCl) or HS (8% NaCl) diet for the whole gestation. Offspring were maintained on NS diets. Renal interlobar arteries in offspring were tested for vascular responses to phenylephrine (Phe), K(+) channels and signal pathways related to sGC. Phe induced higher vessel tension in interlobar arteries of the HS offspring. Following pretreatment with BKCa channel inhibitor iberiotoxin, Phe-mediated vasoconstrictions were decreased in HS offspring compared to NS. Phe-mediated constrictions following pretreatment with NO synthase inhibitor N(G)-nitro-l-arginine methyl ester or sGC inhibitor 1H-1,2,4-oxadiazolo-4,3-quinoxalin-1-one in the HS offspring were less sensitive than NS. The whole-cell K(+) currents and the component of BKCa channels were not changed in smooth muscle cells from interlobar arteries, whereas the K(+) currents stimulated by sGC activator BAY41-2272 were reduced in the HS offspring. The protein expressions of sGC β1 and β2 in the interlobar arteries of HS offspring were reduced. The results showed that chronic overintake of salt during pregnancy could increase renal vascular tone in the offspring. The affected signal pathways included down-regulation of sGC function and expression.

Accelerated age-related decline in renal and vascular function in female rats following early-life growth restriction

Many studies report sexual dimorphism in the fetal programming of adult disease. We hypothesized that there would be differences in the age-related decline in renal function between male and female intrauterine growth-restricted rats. Early-life growth restriction was induced in rat offspring by administering a low-protein diet (LPD; 8.7% casein) to dams during pregnancy and lactation. Control dams were fed a normal-protein diet (NPD; 20% casein). Mean arterial pressure (MAP) and renal structure and function were assessed in 32- and 100-wk-old offspring. Mesenteric artery function was examined at 100 wk using myography. At 3 days of age, body weight was ∼24% lower ( P < 0.0001) in LPD offspring; this difference was still apparent at 32 wk but not at 100 wk of age. MAP was not different between the male NPD and LPD groups at either age. However, MAP was greater in LPD females compared with NPD females at 100 wk of age (∼10 mmHg; P < 0.001). Glomerular filtration rate declined with age in the NPD male, LPD male and LPD female offspring (∼45%, all P < 0.05), but not in NPD female offspring. Mesenteric arteries in the aged LPD females had reduced sensitivity to nitric oxide donors compared with their NPD counterparts, suggesting that vascular dysfunction may contribute to the increased risk of disease in aged females. In conclusion, females growth-restricted in early life were no longer protected from an age-related decline in renal and arterial function, and this was associated with increased arterial pressure without evidence of renal structural damage.

Chronic fetal exposure to caffeine altered resistance vessel functions via RyRs-BKCa down-regulation in rat offspring

Caffeine modifies vascular/cardiac contractility. Embryonic exposure to caffeine altered cardiac functions in offspring. This study determined chronic influence of prenatal caffeine on vessel functions in offspring. Pregnant Sprague-Dawley rats (5-month-old) were exposed to high dose of caffeine, their offspring (5-month-old) were tested for vascular functions in mesenteric arteries (MA) and ion channel activities in smooth muscle cells. Prenatal exposure to caffeine increased pressor responses and vasoconstrictions to phenylephrine, accompanied by enhanced membrane depolarization. Large conductance Ca2⁺-activated K⁺ (BK_Ca) channels in buffering phenylephrine-induced vasoconstrictions was decreased, whole cell BK_Ca currents and spontaneous transient outward currents (STOCs) were decreased. Single channel recordings revealed reduced voltage/Ca²⁺ sensitivity of BK_Ca channels. BK_Ca α-subunit expression was unchanged, BK_Ca β1-subunit and sensitivity of BK_Ca to tamoxifen were reduced in the caffeine offspring as altered biophysical properties of BK_Ca in the MA. Simultaneous [Ca²⁺]_i fluorescence and vasoconstriction testing showed reduced Ca²⁺, leading to diminished BK_Ca activation via ryanodine receptor Ca²⁺ release channels (RyRs), causing enhanced vascular tone. Reduced RyR1 was greater than that of RyR3. The results suggest that the altered STOCs activity in the caffeine offspring could attribute to down-regulation of RyRs-BK_Ca, providing new information for further understanding increased risks of hypertension in developmental origins.

Antenatal Antioxidant Prevents Nicotine-Mediated Hypertensive Response in Rat Adult Offspring

Previous studies have demonstrated that perinatal nicotine exposure increased blood pressure (BP) in adult offspring. However, the underlying mechanisms were unclear. The present study tested the hypothesis that perinatal nicotine-induced programming of hypertensive response is mediated by enhanced reactive oxygen species (ROS) in the vasculature. Nicotine was administered to pregnant rats via subcutaneous osmotic mini-pumps from Day 4 of gestation to Day 10 after birth, in the absence or presence of the ROS inhibitor N-acetyl-cysteine (NAC) in the drinking water. Experiments were conducted in 8-mo-old male offspring. Perinatal nicotine treatment resulted in a significant increase in arterial ROS production in offspring, which was abrogated by NAC. Angiotensin II (Ang II)-induced BP responses were significantly higher in nicotine-treated group than in saline-treated control group, and NAC treatment blocked the nicotine-induced increase in BP response. Consistent with that, the nicotine treatment significantly increased both Ang II-induced and phorbol [12, 13]-dibutyrate (PDBu, a Prkc activator)-induced arterial contractions in adult offspring, which were blocked by NAC treatment. In addition, perinatal nicotine treatment significantly attenuated acetylcholine-induced arterial relaxation in offspring, which was also inhibited by NAC treatment. Results demonstrate that inhibition of ROS blocks the nicotine-induced increase in arterial reactivity and BP response to vasoconstrictors in adult offspring, suggesting a key role for increased oxidative stress in nicotine-induced developmental programming of hypertensive phenotype in male offspring.

Chronic hypoxia in pregnancy affected vascular tone of renal interlobar arteries in the offspring

Hypoxia during pregnancy could affect development of fetuses as well as cardiovascular systems in the offspring. This study was the first to demonstrate the influence and related mechanisms of prenatal hypoxia (PH) on renal interlobar arteries (RIA) in the 5-month-old male rat offspring. Following chronic hypoxia during pregnancy, phenylephrine induced significantly higher pressor responses and greater vasoconstrictions in the offspring. Nitric oxide mediated vessel relaxation was altered in the RIA. Phenylephrine-stimulated free intracellular calcium was significantly higher in the RIA of the PH group. The activity and expression of L-type calcium channel (Cav1.2), not T-type calcium channel (Cav3.2), was up-regulated. The whole-cell currents of calcium channels and the currents of Cav1.2 were increased compared with the control. In addition, the whole-cell K⁺ currents were decreased in the offspring exposed to prenatal hypoxia. Activity of large-conductance Ca²⁺-activated K⁺ channels and the expression of MaxiKα was decreased in the PH group. The results provide new information regarding the influence of prenatal hypoxia on the development of the renal vascular system, and possible underlying cellular and ion channel mechanisms involved.

Fetal programming and cardiovascular pathology

Low birth weight serves as a crude proxy for impaired growth during fetal life and indicates a failure for the fetus to achieve its full growth potential. Low birth weight can occur in response to numerous etiologies that include complications during pregnancy, poor prenatal care, parental smoking, maternal alcohol consumption, or stress. Numerous epidemiological and experimental studies demonstrate that birth weight is inversely associated with blood pressure and coronary heart disease. Sex and age impact the developmental programming of hypertension. In addition, impaired growth during fetal life also programs enhanced vulnerability to a secondary insult. Macrosomia, which occurs in response to maternal obesity, diabetes, and excessive weight gain during gestation, is also associated with increased cardiovascular risk. Yet, the exact mechanisms that permanently change the structure, physiology, and endocrine health of an individual across their lifespan following altered growth during fetal life are not entirely clear. Transmission of increased risk from one generation to the next in the absence of an additional prenatal insult indicates an important role for epigenetic processes. Experimental studies also indicate that the sympathetic nervous system, the renin angiotensin system, increased production of oxidative stress, and increased endothelin play an important role in the developmental programming of blood pressure in later life. Thus, this review will highlight how adverse influences during fetal life and early development program an increased risk for cardiovascular disease including high blood pressure and provide an overview of the underlying mechanisms that contribute to the fetal origins of cardiovascular pathology.

Sex differences in the developmental origins of cardiovascular disease

The Developmental Origins of Health and Disease (DOHaD) proposes that adverse events during early life program an increased risk for cardiovascular disease. Experimental models provide proof of concept but also indicate that insults during early life program sex differences in adult blood pressure and cardiovascular risk. This review will highlight the potential mechanisms that contribute to the etiology of sex differences in the developmental programming of cardiovascular disease.

Muscarinic-mediated vasoconstriction in human, rat and sheep umbilical cords and related vasoconstriction mechanisms

OBJECTIVE

The umbilical cord provides nutrition and oxygen to the fetus. The aim of this study was to determine the effects of acetylcholine (ACh) on umbilical cords from humans and other mammals, and the mechanisms of ACh-mediated vasoconstriction in the human umbilical cord.

DESIGN

Human and animal umbilical cords used in vascular and cellular experiments.

SETTING

Institute for Fetology, First Hospital of Soochow University, Suzhou, China.

POPULATION

A total of 85 pregnant women, 16 Sprague Dawley rats and seven pregnant sheep.

METHODS

Umbilical cord veins and arteries from humans, rats and sheep, aortas and mesenteric arteries from rats, and mesenteric, carotid and femoral arteries from ovine fetuses were used to compare vascular functions in response to ACh and to determine the mechanisms of ACh-mediated umbilical vasoconstriction. Vascular tension and ion channel currents were measured on isolated vessels and smooth muscle cells from human umbilical cords.

MAIN OUTCOME MEASURES

Provision of new evidence to conclude that ACh-stimulated vasoconstriction is common to all umbilical cords, and cellular mechanisms are linked to potassium channels.

RESULTS

ACh caused reliable vasoconstriction in umbilical veins/arteries in humans, rats and sheep, but not in any other vessels, including fetal vessels. Atropine inhibited the effects of ACh. The mRNA of ACh-muscarinic receptor subtypes M1 -M5 was expressed in human umbilical vessels. The protein kinase C antagonist GF109203X and the calcium inhibitor nifedipine decreased ACh-induced vasoconstriction in human umbilical vessels. ACh also caused a reduction in whole-cell potassium channel currents and the single-channel current of large-conductance calcium-activated potassium (BKca) channels.

CONCLUSION

Umbilical vessels are significantly different from other vessels in their response to ACh. BKca channels in smooth muscle cells may play important roles in ACh-mediated vasoconstriction in human umbilical cords. This information may be important for fetal medicine and practice with regard to the effect on fetal development of umbilical vascular functions.

Perinatal nicotine exposure increases angiotensin II receptor-mediated vascular contractility in adult offspring

Previous studies have reported that perinatal nicotine exposure causes development of hypertensive phenotype in adult offspring.

Aims

The present study was to determine whether perinatal nicotine exposure causes an epigenetic programming of vascular Angiotensin II receptors (ATRs) and their-mediated signaling pathway leading to heightened vascular contraction in adult offspring.

Main methods

Nicotine was administered to pregnant rats via subcutaneous osmotic minipumps from day 4 of gestation to day 10 after birth. The experiments were conducted at 5 months of age of male offspring.

Key Findings

Nicotine treatment enhanced Angitension II (Ang II)-induced vasoconstriction and 20-kDa myosin light chain phosphorylation (MLC₂₀-P) levels. In addition, the ratio of Ang II-induced tension/MLC-P was also significantly increased in nicotine-treated group compared with the saline group. Nicotine-mediated enhanced constrictions were not directly dependent on the changes of [Ca²⁺]_i concentrations but dependent on Ca²⁺ sensitivity. Perinatal nicotine treatment significantly enhanced vascular ATR type 1a (AT_1aR) but not AT_1bR mRNA levels in adult rat offspring, which was associated with selective decreases in DNA methylation at AT_1aR promoter. Contrast to the effect on AT_1aR, nicotine decreased the mRNA levels of vascular AT₂R gene, which was associated with selective increases in DNA methylation at AT₂R promoter.

Significance

Our results indicated that perinatal nicotine exposure caused an epigenetic programming of vascular ATRs and their-mediated signaling pathways, and suggested that differential regulation of AT₁R/AT₂R gene expression through DNA methylation mechanism may be involved in nicotine-induced heightened vasoconstriction and development of hypertensive phenotype in adulthood.

Effect of low birth weight on women's health

PURPOSE

The theory of the developmental origins of health and disease hypothesizes that low birth weight (≤5.5 lb) indicative of poor fetal growth is associated with an increased risk of chronic, noncommunicable disease in later life, including hypertension, type 2 diabetes mellitus, and osteoporosis. Whether women are at greater risk than men is not clear. Experimental studies that mimic the cause of slow fetal growth are being used to examine the underlying mechanisms that link a poor fetal environment with later chronic disease and investigate how sex and age affect programmed risk. Thus, the aims of this review are to summarize the current literature related to the effect of low birth weight on women's health and provide insight into potential mechanisms that program increased risk of chronic disease across the lifespan.

METHODS

A search of PubMed was performed with the keywords low birth weight, women's health, female, and sex differences; additional terms included blood pressure, hypertension, renal, cardiovascular, obesity, glucose intolerance, type 2 diabetes, osteoporosis, bone health, reproductive senescence, menopause, and aging.

FINDINGS

The major chronic diseases associated with low birth weight include high blood pressure and cardiovascular disease, impaired glucose homeostasis and type 2 diabetes, impaired bone mass and osteoporosis, and early reproductive aging.

IMPLICATIONS

Low birth weight increases the risk of chronic disease in men and women. Low birth weight is also associated with increased risk of early menopause. Further studies are needed to fully address the effect of sex and age on the developmental programming of adult health and disease in women across their lifespan.

ADAMTS-7 expression increases in the early stage of angiotensin II-induced renal injury in elderly mice

BACKGROUND/AIMS

We investigated the recently described family of proteinases, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTs), and matrix metalloproteinases (MMPs) as inflammatory mediators in inflammatory kidney damage by studying ADAMTS-1, -4, and -7 and MMP-9 expression in elderly mouse kidneys after angiotensin II (Ang II) administration.

METHODS

Ang II (2.5 µg/kg/min) or norepinephrine (8.3 µg/kg/min) was subcutaneously infused in old mice. Renal injury was assessed by hematoxylin-eosin staining, 24-h albuminuria, and immunohistochemistry to evaluate inflammatory cell markers. The mRNA and protein expression of ADAMTS-1, -4, and -7 and MMP-9 were determined using real-time PCR, Western blot, and immunohistochemistry 3 days after Ang II or norepinephrine administration.

RESULTS

Elderly mice in the Ang II group developed hypertension and pathological kidney damage. The mRNA and protein levels of ADAMTS-7 in the Ang II group were 3.3 ± 1.1 (P = 0.019) and 1.6 ± 0.1 (P = 0.047) vs. 1.0 ± 0.1 and 1.0 ± 0.1 in the control group on day 3. In contrast, treatment with the hypertensive agent norepinephrine did not lead to obvious renal damage or an increase in renal ADAMTS-7 expression.

CONCLUSIONS

Renal ADAMTS-7 expression was induced by Ang II in elderly mice. The overexpression of ADATMTS-7 might contribute to early inflammatory kidney damage associated with aging.

Sex differences in the developmental programming of hypertension

Experimental models of developmental programming provide proof of concept and support Barker's original findings that link birthweight and blood pressure. Many experimental models of developmental insult demonstrate a sex difference with male offspring exhibiting a higher blood pressure in young adulthood relative to their age-matched female counterparts. It is well recognized that men exhibit a higher blood pressure relative to age-matched women prior to menopause. Yet, whether this sex difference is noted in individuals born with low birthweight is not clear. Sex differences in the developmental programming of blood pressure may originate from innate sex-specific differences in expression of the renin angiotensin system that occur in response to adverse influences during early life. Sex differences in the developmental programming of blood pressure may also involve the influence of the hormonal milieu on regulatory systems key to the long-term control of blood pressure such as the renin angiotensin system in adulthood. In addition, the sex difference in blood pressure in offspring exposed to a developmental insult may involve innate sex differences in oxidative status or the endothelin system or may be influenced by age-dependent changes in the developmental programming of cardiovascular risk factors such as adiposity. Therefore, this review will highlight findings from different experimental models to provide the current state of knowledge related to the mechanisms that contribute to the aetiology of sex differences in the developmental programming of blood pressure and hypertension.