Early life stress enhances angiotensin II-mediated vasoconstriction by reduced endothelial nitric oxide buffering capacity

Guidelines for in vivo models of developmental programming of cardiovascular disease risk

Research using animals depends on the generation of offspring for use in experiments or for the maintenance of animal colonies. Although not considered by all, several different factors preceding and during pregnancy, as well as during lactation, can program various characteristics in the offspring. Here, we present the most common models of developmental programming of cardiovascular outcomes, important considerations for study design, and provide guidelines for producing and reporting rigorous and reproducible cardiovascular studies in offspring exposed to normal conditions or developmental insult. These guidelines provide considerations for the selection of the appropriate animal model and factors that should be reported to increase rigor and reproducibility while ensuring transparent reporting of methods and results.

Association of early life adversity with cardiovascular disease and its potential mechanisms: a narrative review

Strong epidemiological evidence has shown that early life adversity (ELA) has a profound negative impact on health in adulthood, including an increased risk of cardiovascular disease, the leading cause of death worldwide. Here, we review cohort studies on the effects of ELA on cardiovascular outcomes and the possible underlying mechanisms. In addition, we summarize relevant studies in rodent models of ELA. This review reveals that the prevalence of ELA varies between regions, time periods, and sexes. ELA increases cardiovascular health risk behaviors, susceptibility to mental illnesses, and neuroendocrine and immune system dysfunction in humans. Rodent models of ELA have been developed and show similar cardiovascular outcomes to those in humans but cannot fully replicate all ELA subtypes. Therefore, combining cohort and rodent studies to further investigate the mechanisms underlying the association between ELA and cardiovascular diseases may be a feasible future research strategy.

Association of select psychiatric disorders with incident brain aneurysm and subarachnoid hemorrhage among veterans

Background

Brain aneurysms represent a significant cause of hemorrhagic stroke. Prior research has demonstrated links between stress and stroke, including brain aneurysms. We aimed to determine relationships between select psychiatric disorders and aneurysms and aneurysmal SAH.

Methods

We performed retrospective, case-control study of a National Veterans Affairs population with two experimental groups (aneurysm-only and aneurysmal SAH) and 10-fold controls per group matched by age, date, and clinical data source. The studied the presence of 4 psychiatric disorders: Posttraumatic stress disorder (PTSD), major depressive disorder (MDD), generalized anxiety disorder (GAD), and other mood disorders. Our main outcomes Unadjusted and multivariable adjusted ORs of PTSD, MDD, GAD, and mood disorders within aneurysm-only and aSAH groups.

Results

In 6,320,789 US Veterans who were enrolled for at least 5 years in Medicare and/or the Veterans Health Administration, we identified 35,094 cases of aneurysm without SAH and 5,749 cases of aneurysm with SAH between 1/2005 and 12/2019. In analyses adjusted for sex, hypertension, and tobacco use, patients with aneurysm were more likely than matched controls to have a history of PTSD (OR 1.48), MDD (OR 1.33), GAD (OR 1.26), and other mood disorders (OR 1.34) (all p-values < 0.0001). Similarly, patients with aSAH were more likely than controls to have a history of PTSD (OR 1.35), MDD (OR 1.38), GAD (OR 1.18), and other mood disorders (OR 1.30) (all p-values < 0.0001).

Conclusion

The study, the largest of its kind, further suggests links between psychiatric disorders and stroke. This is important as patients with aneurysms are not routinely screened for such psychiatric risk factors. Additional research on this topic could lead to novel strategies to improve stroke prevention.

Prenatal Morphine Exposure Increases Cardiovascular Disease Risk and Programs Neurogenic Hypertension in the Adult Offspring

BACKGROUND

The opioid overdose and opioid use disorder epidemics are concomitant with increased metabolic and CVD risk. Although opioid use disorder causes adverse pregnancy outcomes, the offspring's cardiovascular health is understudied. We hypothesized that offspring exposed to in utero morphine exposure (IUME) would show increased CVD risk factors and endogenous opioid system dysregulation.

METHODS

Sprague Dawley dams were treated with saline (vehicle, n=10) or escalating doses of morphine (5-20 mg/kg per day, SC, n=10) during gestation. Cardiovascular and metabolic parameters were assessed in adult offspring.

RESULTS

Litter size and pups' birth weight were not different in response to IUME. Female and male IUME offspring showed reduced body length at birth (P<0.05) and body weight from weeks 1 to 3 of life (P<0.05), followed by a catch-up growth effect. By week 16, female and male IUME rats showed reduced tibia length (P<0.05) and fat mass. IUME increases the mean arterial pressure and the depressor response to mecamylamine (5 mg/kg per day, IP) induced by IUME were abolished by a chronic treatment with an alpha-adrenergic receptor blocker (prazosin; 1 mg/kg per day, IP). Although circulating levels of angiotensin peptides were similar between groups, IUME exacerbated maximal ex vivo Ang (angiotensin) II-induced vasoconstriction (P<0.05) and induced endothelial dysfunction in a sex-specific manner (P<0.05). Proenkephalin, an endogenous opioid peptide that lowers blood pressure and sympathetic-mediated vasoconstriction, showed reduced mRNA expression in the heart, aorta, and kidneys from morphine versus vehicle group (P<0.05).

CONCLUSIONS

Among the effects of IUME, neurogenic hypertension, vascular dysfunction, and metabolic dysfunction could be associated with the dysregulation of the endogenous opioid system.

Perinatal intermittent hypoxia increases early susceptibility to ANG II-induced hypertension in adult male but not in female Sprague-Dawley rats

Prenatal, perinatal, and adulthood exposure to chronic intermittent hypoxia (IH) increases blood pressure in rodents. Males exposed to chronic IH have higher blood pressure versus females. However, it is unknown if this same-sex difference exists with acute perinatal IH. We tested the hypothesis that acute perinatal IH increases baseline blood pressure and enhances sensitivity to angiotensin II (ANG II)-induced hypertension in male Sprague-Dawley rats. Male and female pups were randomized to control (room air) or IH (10 min of ∼10% O2 for 3 times/day) for the first 8 days of life. IH decreased oxygen saturation, as confirmed via a pulse oximeter. Pups were weaned at postnatal day 21. Blood pressure was measured via telemetry beginning at 14 wk of age and analyzed separately into light and dark phases to assess circadian rhythm. Osmotic minipumps to deliver ANG II were implanted at 15 wk of age. Perinatal IH exposure did not alter baseline blood pressure. One week of ANG II treatment increased blood pressure in light and dark periods in males exposed to IH versus control; there was no effect in females. Blood pressure among the groups was comparable following 2 wk of ANG II infusion. Perinatal IH did not change the circadian rhythm. Following ANG II treatment, indexes of renal injury were measured. Perinatal IH did not alter kidney size, structure, nephron number, or creatinine clearance. These data indicate that acute perinatal IH enhances early ANG II-induced hypertension in males, independent of nephron loss or decreases in body weight or kidney function.NEW & NOTEWORTHY The impact of acute intermittent hypoxia (IH) in early life on blood pressure in adulthood is unknown. This study used a new model exposing female and male rat pups to acute IH in the first 8 days of life, without exposing the dam. Although baseline blood pressure was not altered in adulthood, IH increased susceptibility to angiotensin II hypertension only in males, supporting increased susceptibility of males exposed to IH to a second cardiovascular stressor.

Hypertension and renal disease programming: focus on the early postnatal period

The developmental origin of hypertension and renal disease is a concept highly supported by strong evidence coming from both human and animal studies. During development there are periods in which the organs are more vulnerable to stressors. Such periods of susceptibility are also called 'sensitive windows of exposure'. It was shown that as earlier an adverse event occurs; the greater are the consequences for health impairment. However, evidence show that the postnatal period is also quite important for hypertension and renal disease programming, especially in rodents because they complete nephrogenesis postnatally, and it is also important during preterm human birth. Considering that the developing kidney is vulnerable to early-life stressors, renal programming is a key element in the developmental programming of hypertension and renal disease. The purpose of this review is to highlight the great number of studies, most of them performed in animal models, showing the broad range of stressors involved in hypertension and renal disease programming, with a particular focus on the stressors that occur during the early postnatal period. These stressors mainly include undernutrition or specific nutritional deficits, chronic behavioral stress, exposure to environmental chemicals, and pharmacological treatments that affect some important factors involved in renal physiology. We also discuss the common molecular mechanisms that are activated by the mentioned stressors and that promote the appearance of these adult diseases, with a brief description on some reprogramming strategies, which is a relatively new and promising field to treat or to prevent these diseases.

Preclinical animal models of mental illnesses to translate findings from the bench to the bedside: Molecular brain mechanisms and peripheral biomarkers associated to early life stress or immune challenges

Animal models are useful preclinical tools for studying the pathogenesis of mental disorders and the effectiveness of their treatment. While it is not possible to mimic all symptoms occurring in humans, it is however possible to investigate the behavioral, physiological and neuroanatomical alterations relevant for these complex disorders in controlled conditions and in genetically homogeneous populations. Stressful and infection-related exposures represent the most employed environmental risk factors able to trigger or to unmask a psychopathological phenotype in animals. Indeed, when occurring during sensitive periods of brain maturation, including pre, postnatal life and adolescence, they can affect the offspring's neurodevelopmental trajectories, increasing the risk for mental disorders. Not all stressed or immune challenged animals, however, develop behavioral alterations and preclinical animal models can explain differences between vulnerable or resilient phenotypes. Our review focuses on different paradigms of stress (prenatal stress, maternal separation, social isolation and social defeat stress) and immune challenges (immune activation in pregnancy) and investigates the subsequent alterations in several biological and behavioral domains at different time points of animals' life. It also discusses the "double-hit" hypothesis where an initial early adverse event can prime the response to a second negative challenge. Interestingly, stress and infections early in life induce the activation of the hypothalamic-pituitary-adrenal (HPA) axis, alter the levels of neurotransmitters, neurotrophins and pro-inflammatory cytokines and affect the functions of microglia and oxidative stress. In conclusion, animal models allow shedding light on the pathophysiology of human mental illnesses and discovering novel molecular drug targets for personalized treatments.

Programming of Vascular Dysfunction by Maternal Stress: Immune System Implications

A growing body of evidence highlights that several insults during pregnancy impact the vascular function and immune response of the male and female offspring. Overactivation of the immune system negatively influences cardiovascular function and contributes to cardiovascular disease. In this review, we propose that modulation of the immune system is a potential link between prenatal stress and offspring vascular dysfunction. Glucocorticoids are key mediators of stress and modulate the inflammatory response. The potential mechanisms whereby prenatal stress negatively impacts vascular function in the offspring, including poor hypothalamic–pituitary–adrenal axis regulation of inflammatory response, activation of Th17 cells, renin–angiotensin–aldosterone system hyperactivation, reactive oxygen species imbalance, generation of neoantigens and TLR4 activation, are discussed. Alterations in the immune system by maternal stress during pregnancy have broad relevance for vascular dysfunction and immune-mediated diseases, such as cardiovascular disease.

Liver circadian clock disruption alters perivascular adipose tissue gene expression and aortic function in mice

The liver plays a central role that influences cardiovascular disease outcomes through regulation of glucose and lipid metabolism. It is recognized that the local liver molecular clock regulates some liver-derived metabolites. However, it is unknown whether the liver clock may impact cardiovascular function. Perivascular adipose tissue (PVAT) is a specialized type of adipose tissue surrounding blood vessels. Importantly, cross talk between the endothelium and PVAT via vasoactive factors is critical for vascular function. Therefore, we designed studies to test the hypothesis that cardiovascular function, including PVAT function, is impaired in mice with liver-specific circadian clock disruption. Bmal1 is a core circadian clock gene, thus studies were undertaken in male hepatocyte-specific Bmal1 knockout (HBK) mice and littermate controls (i.e., flox mice). HBK mice showed significantly elevated plasma levels of β-hydroxybutyrate, nonesterified fatty acids/free fatty acids, triglycerides, and insulin-like growth factor 1 compared with flox mice. Thoracic aorta PVAT in HBK mice had increased mRNA expression of several key regulatory and metabolic genes, Ppargc1a, Pparg, Adipoq, Lpl, and Ucp1, suggesting altered PVAT energy metabolism and thermogenesis. Sensitivity to acetylcholine-induced vasorelaxation was significantly decreased in the aortae of HBK mice with PVAT attached compared with aortae of HBK mice with PVAT removed, however, aortic vasorelaxation in flox mice showed no differences with or without attached PVAT. HBK mice had a significantly lower systolic blood pressure during the inactive period of the day. These new findings establish a novel role of the liver circadian clock in regulating PVAT metabolic gene expression and PVAT-mediated aortic vascular function.

Intrarenal Renin Angiotensin System Imbalance During Postnatal Life Is Associated With Increased Microvascular Density in the Mature Kidney

Environmental stress during early life is an important factor that affects the postnatal renal development. We have previously shown that male rats exposed to maternal separation (MatSep), a model of early life stress, are normotensive but display a sex-specific reduced renal function and exacerbated angiotensin II (AngII)-mediated vascular responses as adults. Since optimal AngII levels during postnatal life are required for normal maturation of the kidney, this study was designed to investigate both short- and long-term effect of MatSep on (1) the renal vascular architecture and function, (2) the intrarenal renin-angiotensin system (RAS) components status, and (3) the genome-wide expression of genes in isolated renal vasculature. Renal tissue and plasma were collected from male rats at different postnatal days (P) for intrarenal RAS components mRNA and protein expression measurements at P2, 6, 10, 14, 21, and 90 and microCT analysis at P21 and 90. Although with similar body weight and renal mass trajectories from P2 to P90, MatSep rats displayed decreased renal filtration capacity at P90, while increased microvascular density at both P21 and P90 (p < 0.05). MatSep increased renal expression of renin, and angiotensin type 1 (AT1) and type 2 (AT2) receptors (p < 0.05), but reduced ACE2 mRNA expression and activity from P2-14 compared to controls. However, intrarenal levels of AngII peptide were reduced (p < 0.05) possible due to the increased degradation to AngIII by aminopeptidase A. In isolated renal vasculature from neonates, Enriched Biological Pathways functional clusters (EBPfc) from genes changed by MatSep reported to modulate extracellular structure organization, inflammation, and pro-angiogenic transcription factors. Our data suggest that male neonates exposed to MatSep could display permanent changes in the renal microvascular architecture in response to intrarenal RAS imbalance in the context of the atypical upregulation of angiogenic factors.

Interactions of the Brain Renin-Angiotensin-System (RAS) and Inflammation in the Sensitization of Hypertension

Mounting evidence indicates that the renin-angiotensin (RAS) and immune systems interact with one another in the central nervous system (CNS) and that they are importantly involved in the pathogenesis of hypertension. Components comprising the classic RAS were first identified in the periphery, and subsequently, similar factors were found to be generated de novo in many different organs including the brain. There is humoral-neural coupling between the systemic and brain RASs, which is important for controlling sympathetic tone and the release of endocrine factors that collectively determine blood pressure (BP). Similar to the interactions between the systemic and brain RASs is the communication between the peripheral and brain immune systems. Systemic inflammation activates the brain’s immune response. Importantly, the RAS and inflammatory factors act synergistically in brain regions involved in the regulation of BP. This review presents evidence of how such interactions between the brain RAS and central immune mechanisms contribute to the pathogenesis of hypertension. Emphasis focuses on the role of these interactions to induce neuroplastic changes in a central neural network resulting in hypertensive response sensitization (HTRS). Neuroplasticity and HTRS can be induced by challenges (stressors) presented earlier in life such as a low-dose of angiotensin II or high fat diet (HFD) feeding in adults. Similarly, the offspring of mothers with gestational hypertension or of mothers ingesting a HFD during pregnancy are reprogrammed and manifest HTRS when exposed to new stressors as adults. Consideration of the actions and interactions of the brain RAS and inflammatory mediators in the context of the induction and expression of HTRS will provide insights into the etiology of high BP that may lead to new strategies for the prevention and treatment of hypertension.

Maternal separation-induced increases in vascular stiffness are independent of circulating angiotensinogen levels

The renin-angiotensin system (RAS) precursor angiotensinogen (AGT) has been implicated in the functional and mechanical alterations of the vascular wall in response to high-fat diet (HFD). Previously, we showed that HFD exacerbates angiotensin II-induced constriction in isolated aortic rings from male rats exposed to maternal separation (MatSep), a model of early-life stress. Thus, the aim of this study was to investigate whether MatSep increases AGT secretion promoting vascular stiffness in rats fed a HFD. Male Wistar-Kyoto MatSep offspring were separated (3 h/day, postnatal days 2-14), and undisturbed littermates were used as controls. At weaning, rats were fed for 17 wk a normal diet (ND) or a HFD, 18% or 60% kcal from fat, respectively. In plasma, there was a main effect of MatSep reducing AGT concentration (P < 0.05) but no effect due to diet. In urine, ND-fed MatSep rats displayed higher AGT concentrations that were further increased by HFD (P < 0.05 vs. control). AGT mRNA abundance and protein expression were increased in adipose tissue from HFD-fed MatSep rats compared with control rats (P < 0.05). No significant differences in liver and kidney AGT levels were found between groups. In addition, MatSep augmented vascular stiffness assessed on freshly isolated aortic rings from ND-fed rats (P < 0.05), yet HFD did not worsen vascular stiffness in either MatSep or control rats. There was no correlation between plasma AGT and vascular stiffness in ND-fed rats; however, this relationship was negative in HFD-fed MatSep rats only (P < 0.05). Therefore, this study shows that MatSep-induced increases in vascular stiffness are independent of diet or plasma AGT.NEW & NOTEWORTHY This study demonstrates that there was no correlation between circulating levels of angiotensinogen (AGT) and the development of vascular stiffness in rats exposed to early-life stress and fed a normal diet. This study also shows that early-life stress-induced hypersensitive vascular contractility to angiotensin II in rats fed a high-fat diet is independent of circulating levels of AGT and occurs without further progression of vascular stiffness. Our data show that early-life stress primes the adipose tissue to secrete AGT in a sex- and species-independent fashion.

Maternal Separation Induces Long-Term Alterations in the Cardiac Oxytocin Receptor and Cystathionine γ-Lyase Expression in Mice

We recently showed that blunt chest trauma reduced the expression of the myocardial oxytocin receptor (Oxtr), which was further aggravated by genetic deletion of the H₂S-producing enzyme cystathionine γ-lyase (CSE). Exogenous H₂S supplementation restored myocardial Oxtr expression under these conditions. Early life stress (ELS) is a risk factor for cardiovascular disease by affecting vascular and heart structures. Therefore, we tested the hypotheses that (i) ELS affects cardiac Oxtr and CSE expressions and (ii) Oxtr and CSE expression patterns depend on the duration of stress exposure. Thus, two stress paradigms were compared: long- and short-term separation stress (LTSS and STSS, respectively). Cardiac Oxtr expression was differentially affected by the two stress paradigms with a significant reduction after LTSS and a significant increase after STSS. CSE expression, which was significantly reduced in Oxtr^−/− knockout hearts, was downregulated and directly related to Oxtr expression in LTSS hearts (r = 0.657, p = 0.012). In contrast, CSE expression was not related to Oxtr upregulation in STSS. Plasma Oxt levels were not affected by either ELS paradigm. The coincidence of LTSS-induced reduction of cardiac Oxtr and reduced CSE expression may suggest a novel pathophysiological link between early life adversities and increased risk for the development of cardiovascular disorders in adulthood.

Differential activation of the renin-angiotensin-aldosterone-system in response to childhood and adulthood trauma

OBJECTIVE

Previous evidence suggested lasting and cumulative effects of traumatization on the renin-angiotensin-aldosterone-system (RAAS). However, it is unclear whether traumas during childhood and those experienced in adulthood differentially impact the RAAS. In this study, we sought to investigate main and putative interactive effects of childhood and adulthood trauma on RAAS functioning.

METHODS

Plasma concentrations of renin and aldosterone were measured in a general population sample (n = 2016). Childhood trauma was assessed using the Childhood Trauma Questionnaire (CTQ), adulthood trauma was measured using the PTSD module of the Structured Clinical Interview of the DSM-IV. Linear regression models were calculated to assess the relations between childhood or adulthood traumatization with renin and aldosterone concentrations.

RESULTS

Exposure to (ß = 0.094; p = 0.01), severity of childhood trauma (ß = 0.004; p = 0.01) were associated with increased aldosterone, but not renin levels. Results were carried by all dimensions of abuse, while childhood neglect was not associated with altered RAAS activity. In contrast, adulthood traumas (ß = 0.113; p < 0.01) were significantly associated with increased renin concentrations. Subjects with PTSD (renin: ß = 0.345; p = 0.01; aldosterone: ß = 0.232; p = 0.04) and those who had been exposed to both childhood and adulthood trauma showed increases in renin (ß = 0.180; p < 0.01) and aldosterone (ß = 0.340; p < 0.01) levels.

DISCUSSION

These findings indicate that trauma is associated with differential alterations of the RAAS depending on the time of traumatization. Moreover, exposure to childhood or adulthood trauma may act synergistically on the RAAS, resulting in severe dysregulation of the RAAS. The results contribute to explain associations between trauma and enhanced risk for physical disease.

Childhood adversity and mechanistic links to hypertension risk in adulthood

Adverse childhood experiences (ACEs), defined as traumatic events in childhood that range from various forms of abuse to household challenges and dysfunction, have devastating consequences on adult health. Epidemiological studies in humans and animal models of early life stress (ELS) have revealed a strong association and insight into the mechanistic link between ACEs and increased risk of cardiovascular disease (CVD). This review focuses on the mechanistic links of ACEs in humans and ELS in mice and rats to vasoactive factors and immune mediators associated with CVD and hypertension risk, as well as sex differences in these phenomena. Major topics of discussion in this review are as follows: (a) epidemiological associations between ACEs and CVD risk focusing on hypertension, (b) evidence for association of ACE exposures to immune-mediated and/or vasoactive pathways, (c) rodent models of ELS-induced hypertension risk, (d) proinflammatory mediators and vasoactive factors as mechanisms of ELS-induced hypertension risk. We also provide some overall conclusions and directions of further research. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Distinct effects of early-life experience and trait aggression on cardiovascular reactivity and recovery

We previously demonstrated independent effects of early-life experience (ELE) and trait aggression (TA) on resting heart rate (HR) and mean arterial pressure (MAP) in rats. The present study examined the effects of TA and ELE on stress-evoked cardiovascular reactivity and recovery. Pups born to Wistar-Kyoto dams were exposed to daily 180-min periods of maternal separation (MS) during the first two weeks of life, and aggression was assessed in adult offspring using the resident-intruder test. Radiotelemetry was then used to record stress-evoked HR and MAP responses in response to: strobe light, novel environment, intruder rat, or restraint. Maximal HR and MAP responses were quantified as indices of reactivity, and exponential decay curves were fitted to determine decay constants as a measure of recovery. Strobe light was the weakest stressor, evoking the lowest increases in MAP and HR, which were significantly greater in MS-exposed rats irrespective of TA. In contrast, reactivity to and recovery from exposure to a novel environment or an intruder were significantly influenced by TA, but not ELE. TA animals exhibited greater reactivity in both of these paradigms, with either decreased (novel environment) or increased (intruder) recovery. Restraint stress induced the largest changes in HR and MAP with the slowest recovery, and these responses were shaped by a significant ELE x TA interaction. These data indicate that cardiovascular reactivity and recovery are influenced by ELE, TA, or ELE x TA interaction depending on stressor aversiveness as well as its physical and psychological dimensions.

Developmental Trajectories of Early Life Stress and Trauma: A Narrative Review on Neurobiological Aspects Beyond Stress System Dysregulation

Early life stressors display a high universal prevalence and constitute a major public health problem. Prolonged psychoneurobiological alterations as sequelae of early life stress (ELS) could represent a developmental risk factor and mediate risk for disease, leading to higher physical and mental morbidity rates in later life. ELS could exert a programming effect on sensitive neuronal brain networks related to the stress response during critical periods of development and thus lead to enduring hyper- or hypo-activation of the stress system and altered glucocorticoid signaling. In addition, alterations in emotional and autonomic reactivity, circadian rhythm disruption, functional and structural changes in the brain, as well as immune and metabolic dysregulation have been lately identified as important risk factors for a chronically impaired homeostatic balance after ELS. Furthermore, human genetic background and epigenetic modifications through stress-related gene expression could interact with these alterations and explain inter-individual variation in vulnerability or resilience to stress. This narrative review presents relevant evidence from mainly human research on the ten most acknowledged neurobiological allostatic pathways exerting enduring adverse effects of ELS even decades later (hypothalamic-pituitary-adrenal axis, autonomic nervous system, immune system and inflammation, oxidative stress, cardiovascular system, gut microbiome, sleep and circadian system, genetics, epigenetics, structural, and functional brain correlates). Although most findings back a causal relation between ELS and psychobiological maladjustment in later life, the precise developmental trajectories and their temporal coincidence has not been elucidated as yet. Future studies should prospectively investigate putative mediators and their temporal sequence, while considering the potentially delayed time-frame for their phenotypical expression. Better screening strategies for ELS are needed for a better individual prevention and treatment.

Maternal separation enhances anticontractile perivascular adipose tissue function in male rats on a high-fat diet

Clinical studies have shown that obesity negatively impacts large arteries' function. We reported that rats exposed to maternal separation (MatSep), a model of early life stress, display enhanced angiotensin II (ANG II)-induced vasoconstriction in aortic rings cleaned of perivascular adipose tissue (PVAT) under normal diet (ND) conditions. We hypothesized that exposure to MatSep promotes a greater loss of PVAT-mediated protective effects on vascular function and loss of blood pressure (BP) rhythm in rats fed a high-fat diet (HFD) when compared with controls. MatSep was performed in male Wistar-Kyoto rats from days 2 to 14 of life. Normally reared littermates served as controls. On ND, aortic rings from MatSep rats with PVAT removed showed increased ANG II-mediated vasoconstriction versus controls; however, rings from MatSep rats with intact PVAT displayed blunted constriction. This effect was exacerbated by an HFD in both groups; however, the anticontractile effect of PVAT was greater in MatSep rats. Acetylcholine-induced relaxation was similar in MatSep and control rats fed an ND, regardless of the presence of PVAT. HFD impaired aortic relaxation in rings without PVAT from MatSep rats, whereas the presence of PVAT improved relaxation in both groups. On an HFD, immunolocalization of vascular smooth muscle-derived ANG-(1-7) and PVAT-derived adiponectin abundances were increased in MatSep. In rats fed an HFD, 24-h BP and BP rhythms were similar between groups. In summary, MatSep enhanced the ability of PVAT to blunt the heightened ANG II-induced vasoconstriction and endothelial dysfunction in rats fed an HFD. This protective effect may be mediated via the upregulation of vasoprotective factors within the adipovascular axis.

Early life stress induces immune priming in kidneys of adult male rats

Early life stress (ELS) in humans is associated with elevated proinflammatory markers. We hypothesized that ELS induces activation of the immune response in a rat model of ELS, maternal separation (MatSep), in adulthood. MatSep involves separating pups from the dam from postnatal day 2 to postnatal day 14 for 3 h/day. Control rats are nonseparated littermates. We determined circulating and renal immune cell numbers, renal immune cell activation markers, renal cytokine levels, and the renal inflammatory gene expression response to low-dose lipopolysaccharide (LPS) in male MatSep and control rats. We observed that MatSep did not change the percentage of gated events for circulating CD3+, CD4+, CD8+, and CD4+/Foxp3+ cells or absolute numbers of mononuclear and T cells in the circulation and kidneys; however, MatSep led to an increase in activation of renal neutrophils as well as CD44+ cells. Renal toll-like receptor 4 (TLR4) and interleukin 1 beta (IL-1β) was significantly increased in MatSep rats, specifically in the outer and inner medulla and distal nephron, respectively. Evaluation of renal inflammatory genes showed that in response to a low-dose LPS challenge (2 mg/kg iv) a total of 20 genes were significantly altered in kidneys from MatSep rats (17 genes were upregulated and 3 were downregulated), as opposed to no significant differences in gene expression in control vs. control + LPS groups. Taken together, these findings indicate that MatSep induces priming of the immune response in the kidney.

Maternal separation diminishes α-adrenergic receptor density and function in renal vasculature from male Wistar-Kyoto rats

Adult rats exposed to maternal separation (MatSep) are normotensive but display lower glomerular filtration rate and increased renal neuroadrenergic drive. The aim of this study was to determine the renal α-adrenergic receptor density and the renal vascular responsiveness to adrenergic stimulation in male rats exposed to MatSep. In addition, baroreflex sensitivity was assessed to determine a component of neural control of the vasculature. Using tissue collected from 4-mo-old MatSep and control rats, α₁-adrenergic receptors (α₁-ARs) were measured in renal cortex and isolated renal vasculature using receptor binding assay, and the α-AR subtype gene expression was determined by RT-PCR. Renal cortical α₁-AR density was similar between MatSep and control tissues (B_max = 44 ± 1 vs. 42 ± 2 fmol/mg protein, respectively); however, MatSep reduced α₁-AR density in renal vasculature (B_max = 47 ± 4 vs. 62 ± 4 fmol/mg protein, P < 0.05, respectively). In a separate group of rats, the pressor, bradycardic, and renal vascular constrictor responses to acute norepinephrine injection (NE, 0.03-0.25 μg/μl) were determined under anesthesia. Attenuated NE-induced renal vasoconstriction was observed in rats exposed to MatSep compared with control (P < 0.05). A third group of rats was infused at steady state with the α₁ agonist phenylephrine (10 μg/min iv) and vasodilator sodium nitroprusside (5 μg/min iv). The difference between the change in heart rate/mean arterial pressure slopes was indicative of reduced baroreflex sensitivity in MatSep vs. control rats (-0.45 ± 0.04 vs. -0.95 ± 0.07 beats·min^-1·mmHg^-1, P < 0.05). These data support the notion that reduced α-adrenergic receptor expression and function in the renal vasculature could develop secondary to MatSep-induced overactivation of the renal neuroadrenergic tone.

Postnatal treatment with metyrapone attenuates the effects of diet-induced obesity in female rats exposed to early-life stress

Experimental studies in rodents have shown that females are more susceptible to exhibiting fat expansion and metabolic disease compared with males in several models of fetal programming. This study tested the hypothesis that female rat pups exposed to maternal separation (MatSep), a model of early-life stress, display an exacerbated response to diet-induced obesity compared with male rats. Also, we tested whether the postnatal treatment with metyrapone (MTP), a corticosterone synthase inhibitor, would attenuate this phenotype. MatSep was performed in WKY offspring by separation from the dam (3 h/day, postnatal days 2-14). Upon weaning, male and female rats were placed on a normal (ND; 18% kcal fat) or high-fat diet (HFD; 60% kcal fat). Nondisturbed littermates served as controls. In male rats, no diet-induced differences in body weight (BW), glucose tolerance, and fat tissue weight and morphology were found between MatSep and control male rats. However, female MatSep rats displayed increased BW gain, fat pad weights, and glucose intolerance compared with control rats (P < 0.05). Also, HFD increased plasma corticosterone (196 ± 51 vs. 79 ± 18 pg/ml, P < 0.05) and leptin levels (1.8 ± 0.4 vs. 1.3 ± 0.1 ng/ml, P < 0.05) in female MatSep compared with control rats, whereas insulin and adiponectin levels were similar between groups. Female control and MatSep offspring were treated with MTP (50 µg/g ip) 30 min before the daily separation. MTP treatment significantly attenuated diet-induced obesity risk factors, including elevated adiposity, hyperleptinemia, and glucose intolerance. These findings show that exposure to stress hormones during early life could be a key event to enhance diet-induced obesity and metabolic disease in female rats. Thus, pharmacological and/or behavioral inflection of the stress levels is a potential therapeutic approach for prevention of early life stress-enhanced obesity and metabolic disease.

Independent effects of early-life experience and trait aggression on cardiovascular function

Early-life experience (ELE) can significantly affect life-long health and disease, including cardiovascular function. Specific dimensions of emotionality also modify risk of disease, and aggressive traits along with social inhibition have been established as independent vulnerability factors for the progression of cardiovascular disease. Yet, the biological mechanisms mediating these associations remain poorly understood. The present study utilized the inherently stress-susceptible and socially inhibited Wistar-Kyoto rats to determine the potential influences of ELE and trait aggression (TA) on cardiovascular parameters throughout the lifespan. Pups were exposed to maternal separation (MS), consisting of daily 3-h separations of the entire litter from postnatal day (P)1 to P14. The rats were weaned at P21, and as adults were instrumented for chronic radiotelemetry recordings of blood pressure and heart rate (HR). Adult aggressive behavior was assessed using the resident-intruder test, which demonstrated that TA was independent of MS exposure. MS-exposed animals (irrespective of TA) had significantly lower resting HR accompanied by increases in HR variability. No effects of MS on resting blood pressure were detected. In contrast, TA correlated with increased resting mean, systolic, and diastolic arterial pressures but had no effect on HR. TA rats (relative to nonaggressive animals) also manifested increased wall-to-lumen ratio in the thoracic aorta, increased sensitivity to phenylephrine-induced vascular contractility, and increased norepinephrine content in the heart. Together these data suggest that ELE and TA are independent factors that impact baseline cardiovascular function.

In Utero Origins of Hypertension: Mechanisms and Targets for Therapy

The developmental origins of health and disease theory is based on evidence that a suboptimal environment during fetal and neonatal development can significantly impact the evolution of adult-onset disease. Abundant evidence exists that a compromised prenatal (and early postnatal) environment leads to an increased risk of hypertension later in life. Hypertension is a silent, chronic, and progressive disease defined by elevated blood pressure (>140/90 mmHg) and is strongly correlated with cardiovascular morbidity/mortality. The pathophysiological mechanisms, however, are complex and poorly understood, and hypertension continues to be one of the most resilient health problems in modern society. Research into the programming of hypertension has proposed pharmacological treatment strategies to reverse and/or prevent disease. In addition, modifications to the lifestyle of pregnant women might impart far-reaching benefits to the health of their children. As more information is discovered, more successful management of hypertension can be expected to follow; however, while pregnancy complications such as fetal growth restriction, preeclampsia, preterm birth, etc., continue to occur, their offspring will be at increased risk for hypertension. This article reviews the current knowledge surrounding the developmental origins of hypertension, with a focus on mechanistic pathways and targets for therapeutic and pharmacologic interventions.

The stress of maternal separation causes misprogramming in the postnatal maturation of rat resistance arteries

We examined the effect of stress in the first 2 wk of life induced by brief periods of daily maternal separation on developmental programming of rat small resistance mesenteric arteries (MAs). In MAs of littermate controls, mRNAs encoding mediators of vasoconstriction, including the α1a-adrenergic receptor, smooth muscle myosin heavy chain, and CPI-17, the inhibitory subunit of myosin phosphatase, increased from after birth through sexual [postnatal day (PND) 35] and full maturity, up to ∼80-fold, as measured by quantitative PCR. This was commensurate with two- to fivefold increases in maximum force production to KCl depolarization, calcium, and the α-adrenergic agonist phenylephrine, and increasing systolic blood pressure. Rats exposed to maternal separation stress as neonates had markedly accelerated trajectories of maturation of arterial contractile gene expression and function measured at PND14 or PND21 (weaning), 1 wk after the end of the stress protocol. This was suppressed by the α-adrenergic receptor blocker terazosin (0.5 mg·kg ip(-1)·day(-1)), indicating dependence on stress activation of sympathetic signaling. Due to the continued maturation of MAs in control rats, by sexual maturity (PND35) and into adulthood, no differences were observed in arterial function or response to a second stressor in rats stressed as neonates. Thus early life stress misprograms resistance artery smooth muscle, increasing vasoconstrictor function and blood pressure. This effect wanes in later stages, suggesting plasticity during arterial maturation. Further studies are indicated to determine whether stress in different periods of arterial maturation may cause misprogramming persisting through maturity and the potential salutary effect of α-adrenergic blockade in suppression of this response.

Losartan activates sirtuin 1 in rat reduced-size orthotopic liver transplantation

AIM: To investigate a possible association between losartan and sirtuin 1 (SIRT1) in reduced-size orthotopic liver transplantation (ROLT) in rats.

METHODS: Livers of male Sprague-Dawley rats (200-250 g) were preserved in University of Wisconsin preservation solution for 1 h at 4 °C prior to ROLT. In an additional group, an antagonist of angiotensin II type 1 receptor (AT1R), losartan, was orally administered (5 mg/kg) 24 h and 1 h before the surgical procedure to both the donors and the recipients. Transaminase (as an indicator of liver injury), SIRT1 activity, and nicotinamide adenine dinucleotide (NAD⁺, a co-factor necessary for SIRT1 activity) levels were determined by biochemical methods. Protein expression of SIRT1, acetylated FoxO1 (ac-FoxO1), NAMPT (the precursor of NAD+), heat shock proteins (HSP70, HO-1) expression, endoplasmic reticulum stress (GRP78, IRE1α, p-eIF2) and apoptosis (caspase 12 and caspase 3) parameters were determined by Western blot. Possible alterations in protein expression of mitogen activated protein kinases (MAPK), such as p-p38 and p-ERK, were also evaluated. Furthermore, the SIRT3 protein expression and mRNA levels were examined.

RESULTS: The present study demonstrated that losartan administration led to diminished liver injury when compared to ROLT group, as evidenced by the significant decreases in alanine aminotransferase (358.3 ± 133.44 vs 206 ± 33.61, P < 0.05) and aspartate aminotransferase levels (893.57 ± 397.69 vs 500.85 ± 118.07, P < 0.05). The lessened hepatic injury in case of losartan was associated with enhanced SIRT1 protein expression and activity (5.27 ± 0.32 vs 6.08 ± 0.30, P < 0.05). This was concomitant with increased levels of NAD⁺ (0.87 ± 0.22 vs 1.195 ± 0.144, P < 0.05) the co-factor necessary for SIRT1 activity, as well as with decreases in ac-FoxO1 expression. Losartan treatment also provoked significant attenuation of endoplasmic reticulum stress parameters (GRP78, IRE1α, p-eIF2) which was consistent with reduced levels of both caspase 12 and caspase 3. Furthermore, losartan administration stimulated HSP70 protein expression and attenuated HO-1 expression. However, no changes were observed in protein or mRNA expression of SIRT3. Finally, the protein expression pattern of p-ERK and p-p38 were not altered upon losartan administration.

CONCLUSION: The present study reports that losartan induces SIRT1 expression and activity, and that it reduces hepatic injury in a ROLT model.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Angiotensin II is required to induce exaggerated salt sensitivity in Dahl rats exposed to maternal separation

We previously reported that maternal separation, rat model of early life stress, enhances pressor responses to acute and chronic stressors. The aims of this study were to determine whether Dahl salt-sensitive (DS) rats subjected to maternal separation (MatSep-DS) as compared to normally reared DS (Ctl-DS) rats show exaggerated blood pressure responses to acute behavioral stressors, such as restraint stress or air jet stress (AJS), or, hypertensive stimuli including chronic high-salt diet (4% NaCl) and angiotensin II (AngII) infusion (200 ng/Kg/min) during 1 week. MatSep was performed in male DS rats for 3 h/day from postnatal days 2-14. At 8 weeks of age, rats were implanted with telemetry transmitters and allowed to recover. Mean arterial pressure (MAP) was not different between MatSep-DS and Ctl-DS rats at baseline (120 ± 2 mmHg vs. 118 ± 1 mmHg, n = 4-8). Blood pressure responses during AJS and restraint stress were not different between MatSep-DS and Ctl-DS at 3 min. However, blood pressure recovery from AJS was significantly impaired in MatSep-DS rats compared to Ctl-DS rats (P < 0.05). 3-h stress-induced similar responses in MatSep and Ctl-DS rats. Chronic blood pressure responses to AngII infusion in rats fed a high-salt diet displayed enhanced MAP in MatSep-DS when compared with Ctl-DS rats (167 ± 5 mmHg vs. 152 ± 2 mmHg, pinteraction <0.05). However, MAP increased similarly in both groups in response to AngII infusion or high-salt diet separately. Renal parameters such as proteinuria, urine flow rate, and urine electrolytes were not different between groups in response to each treatment. In summary, salt sensitivity induces exaggerated blood pressor responses only in presence of AngII due to early life stress.

Antisense versus proopiomelanocortin mRNA reduces vascular risk in a murine model of type-2 diabetes following stress exposure in early post-natal life

Mechanisms of vascular complications in type-2 diabetes patients and animal models are matter of debate. We previously demonstrated that a double-stress model applied to male mice during nursing period produces enduring hyperfunction of endogenous opioid and adrenocorticotropin (ACTH)-corticosteroid systems, accompanied by type-2 diabetes-like alterations in adult animals. Administration of the opioid receptor antagonist naloxone, or of an antisense oligodeoxynucleotide versus proopiomelanocortin mRNA, capable to block the pro-opiomelanocortin-derived peptides β-endorphin and ACTH, selectively prevent these alterations. Here, we investigated alterations produced by our stress model on aorta endothelium-dependent relaxation and contractile responses. Mice, stressed during nursing period, showed in the adulthood hormonal and metabolic type-2 diabetes-like alterations, including hyperglycemia, increased body weight and increased plasma ACTH and corticosterone levels. Ex vivo isolated aorta rings, gathered from stressed mice, were less sensitive to noradrenaline-induced contractions versus controls. This effect was blocked by nitric-oxide synthase-inhibitor l-N(G)-nitroarginine added to bath organ solution. Aorta rings relaxation caused by acetylcholine was enhanced in stressed mice versus controls, but following treatment with the nitric-oxide donor sodium nitroprusside, concentration-relaxation curves in aorta from stressed groups were similar to controls. Therefore, vascular response alterations to physiologic-pharmacologic stimuli were apparently due to nitric-oxide hyperfunction-dependent mechanisms. Aorta functional alterations, and plasma stress hormones enhancement, were prevented in mice stressed and treated with antisense oligodeoxinucleotide, addressed to reduce ACTH- and corticosteroid-mediated hyperfunction. This study demonstrates the key role of ACTH-corticosteroid axis hyperfunction for the triggering of vascular conditions in male adult rodents following postnatal stress in a type-2 diabetes model.

Acute restraint stress induces endothelial dysfunction: role of vasoconstrictor prostanoids and oxidative stress

We hypothesized that acute stress would induce endothelial dysfunction. Male Wistar rats were restrained for 2 h within wire mesh. Functional and biochemical analyses were conducted 24 h after the 2-h period of restraint. Stressed rats showed decreased exploration on the open arms of an elevated-plus maze (EPM) and increased plasma corticosterone concentration. Acute restraint stress did not alter systolic blood pressure, whereas it increased the in vitro contractile response to phenylephrine and serotonin in endothelium-intact rat aortas. NG-nitro-l-arginine methyl ester (l-NAME; nitric oxide synthase, NOS, inhibitor) did not alter the contraction induced by phenylephrine in aortic rings from stressed rats. Tiron, indomethacin and SQ29548 reversed the increase in the contractile response to phenylephrine induced by restraint stress. Increased systemic and vascular oxidative stress was evident in stressed rats. Restraint stress decreased plasma and vascular nitrate/nitrite (NOx) concentration and increased aortic expression of inducible (i) NOS, but not endothelial (e) NOS. Reduced expression of cyclooxygenase (COX)-1, but not COX-2, was observed in aortas from stressed rats. Restraint stress increased thromboxane (TX)B(2) (stable TXA(2) metabolite) concentration but did not affect prostaglandin (PG)F2α concentration in the aorta. Restraint reduced superoxide dismutase (SOD) activity, whereas concentrations of hydrogen peroxide (H(2)O(2)) and reduced glutathione (GSH) were not affected. The major new finding of our study is that restraint stress increases vascular contraction by an endothelium-dependent mechanism that involves increased oxidative stress and the generation of COX-derived vasoconstrictor prostanoids. Such stress-induced endothelial dysfunction could predispose to the development of cardiovascular diseases.

Endothelial AT₁ and AT₂ pathways in aortic responses to angiotensin II after stress and ethanol consumption in rats

Stress and ethanol are important cardiovascular risk factors. Their vascular and blood pressure (BP) effects were evaluated alone and in combination. Adult male Wistar rats (8-10 per group) were separated into control, ethanol (ethanol 20% in drinking water for 6 weeks), stress (restraint 1 h/d 5 d/week for 6 weeks), and ethanol/stress (in combination) groups. Systolic BP was evaluated weekly. Concentration-response curves for contractile responses to angiotensin II in the absence and the presence of losartan (AT1-blocker), PD123-319 (AT2-blocker), L-NAME (nitric oxide synthase inhibitor), or indomethacin (cyclooxygenase inhibitor) were obtained in isolated intact and endothelium-denuded aortas. Effective concentration 50% (EC50) and maximum response (MR) were compared among groups using MANOVA/Tukey tests. Stress and stress plus ethanol increased BP. Ethanol and stress, alone and in combination, did not alter angiotensin responses of intact aortas. PD123-319 decreased MR to angiotensin II in intact aortas from the ethanol and ethanol/stress groups relative to control in the presence of PD123-319. Losartan increased MR to angiotensin II in intact aortas from the stress and ethanol/stress groups relative to control in the presence of losartan. None of the protocols altered angiotensin responses of denuded aortas. Neither indomethacin nor L-NAME altered angiotensin responses of intact aortas from the experimental groups. Thus ethanol and ethanol plus stress may alter endothelial signaling via AT1-receptors, without changing systemic BP. Stress and stress plus ethanol may alter endothelial signaling via AT2-receptors, and thereby increase BP. Knowledge of such vascular changes induced by stress and/or ethanol may contribute to understanding adverse cardiovascular effects of stress and ethanol consumption in humans.

Sex-specific alterations in NOS regulation of vascular function in aorta and mesenteric arteries from spontaneously hypertensive rats compared to Wistar Kyoto rats

The present study tested the hypothesis that spontaneously hypertensive rats (SHR) have impaired nitric oxide synthase (NOS)‐mediated regulation of vascular function versus Wistar‐Kyoto rats (WKY). Aorta and small mesenteric arteries were studied from male and female SHR (M SHR and F SHR) and WKY (M WKY and F WKY). Phenylephrine (PE)‐induced vasoconstriction was greater in aorta of M SHR versus all others (P < 0.05); there were neither sex nor strain differences in PE contraction in mesenteric arteries. The NOS inhibitor l‐Nitro‐Arginine Methyl Ester (l‐NAME) increased PE‐induced vasoconstriction in all rats, although the increase was the least in male SHR (P < 0.05), revealing a blunted vasoconstrictor buffering capacity of NOS. l‐NAME increased sensitivity to PE‐induced constriction only in mesenteric arteries of SHR, although, the maximal percent increase in contraction was comparable among groups. ACh‐induced relaxation was also less in aorta from M SHR versus all others (P < 0.05). ACh relaxation was comparable among groups in mesenteric arteries, although SHR exhibited a greater NOS component to ACh‐induced relaxation than WKY. To gain mechanistic insight into sex and strain differences in vascular function, NOS activity and NOS3 protein expression were measured. Aortic NOS activity was comparable between groups and M SHR had greater NOS3 expression than M WKY. In contrast, although vascular function was largely maintained in mesenteric arteries of SHR, NOS activity was less in SHR versus WKY. In conclusion, M SHR exhibit a decrease in NOS regulation of vascular function compared to F SHR and WKY, although this is not mediated by decreases in NOS activity and/or expression.

The present study tested the hypothesis that spontaneously hypertensive rats (SHR) have impaired nitric oxide synthase (NOS)‐mediated regulation of vascular function versus Wistar‐Kyoto rats (WKY). Aorta and small mesenteric arteries were studied from male and female SHR and WKY. Male SHR showed a decreased NOS regulation of vascular function compared to F SHR and WKY, although this was not mediated by decreases in NOS activity and/or expression.

Transgenerational epigenetics: the role of maternal effects in cardiovascular development

Transgenerational epigenetics, the study of non-genetic transfer of information from one generation to the next, has gained much attention in the past few decades due to the fact that, in many instances, epigenetic processes outweigh direct genetic processes in the manifestation of aberrant phenotypes across several generations. Maternal effects, or the influences of maternal environment, phenotype, and/or genotype on offsprings' phenotypes, independently of the offsprings' genotypes, are a subcategory of transgenerational epigenetics. Due to the intimate role of the mother during early development in animals, there is much interest in investigating the means by which maternal effects can shape the individual. Maternal effects are responsible for cellular organization, determination of the body axis, initiation and maturation of organ systems, and physiological performance of a wide variety of species and biological systems. The cardiovascular system is the first to become functional and can significantly influence the development of other organ systems. Thus, it is important to elucidate the role of maternal effects in cardiovascular development, and to understand its impact on adult cardiovascular health. Topics to be addressed include: (1) how and when do maternal effects change the developmental trajectory of the cardiovascular system to permanently alter the adult's cardiovascular phenotype, (2) what molecular mechanisms have been associated with maternally induced cardiovascular phenotypes, and (3) what are the evolutionary implications of maternally mediated changes in cardiovascular phenotype?

Stress alone or associated with ethanol induces prostanoid release in rat aorta via alpha2-Adrenoceptor

Background

Stress and ethanol are both, independently, important cardiovascular risk factors.

Objective

To evaluate the cardiovascular risk of ethanol consumption and stress exposure, isolated and in association, in male adult rats.

Methods

Rats were separated into 4 groups: Control, ethanol (20% in drinking water for 6 weeks), stress (immobilization 1h day/5 days a week for 6 weeks) and stress/ethanol. Concentration-responses curves to noradrenaline - in the absence and presence of yohimbine, L-NAME or indomethacin - or to phenylephrine were determined in thoracic aortas with and without endothelium. EC50 and maximum response (n=8-12) were compared using two-way ANOVA/Bonferroni method.

Results

Either stress or stress in association with ethanol consumption increased the noradrenaline maximum responses in intact aortas. This hyper-reactivity was eliminated by endothelium removal or by the presence of either indomethacin or yohimbine, but was not altered by the presence of L-NAME. Meanwhile, ethanol consumption did not alter the reactivity to noradrenaline. The phenylephrine responses in aortas both with and without endothelium also remained unaffected regardless of protocol.

Conclusion

Chronic stress increased rat aortic responses to noradrenaline. This effect is dependent upon the vascular endothelium and involves the release of vasoconstrictor prostanoids via stimulation of endothelial alpha-2 adrenoceptors. Moreover, chronic ethanol consumption appeared to neither influence noradrenaline responses in rat thoracic aorta, nor did it modify the increase of such responses observed as a consequence of stress exposure.

Loss of a kidney during fetal life: long-term consequences and lessons learned

Epidemiological studies reveal that children born with a solitary functioning kidney (SFK) have a greater predisposition to develop renal insufficiency and hypertension in early adulthood. A congenital SFK is present in patients with unilateral renal agenesis or unilateral multicystic kidney dysplasia, leading to both structural and functional adaptations in the remaining kidney, which act to mitigate the reductions in glomerular filtration rate and sodium excretion that would otherwise ensue. To understand the mechanisms underlying the early development of renal insufficiency in children born with a SFK, we established a model of fetal uninephrectomy (uni-x) in sheep, a species that similar to humans complete nephrogenesis before birth. This model results in a 30% reduction in nephron number rather than 50%, due to compensatory nephrogenesis in the remaining kidney. Similar to children with a congenital SFK, uni-x sheep demonstrate a progressive increase in arterial pressure and a loss of renal function with aging. This review summarizes the compensatory changes in renal hemodynamics and tubular sodium handling that drive impairments in renal function and highlights the existence of sex differences in the functional adaptations following the loss of a kidney during fetal life.

A mechanistic look at the effects of adversity early in life on cardiovascular disease risk during adulthood

Early origins of adult disease may be defined as adversity or challenges during early life that alter physiological responses and prime the organism to chronic disease in adult life. Adverse childhood experiences or early life stress (ELS) may be considered a silent independent risk factor capable of predicting future cardiovascular disease risk. Maternal separation (MatSep) provides a suitable model to elucidate the underlying molecular mechanisms by which ELS increases the risk to develop cardiovascular disease in adulthood. The aim of this review is to describe the links between behavioural stress early in life and chronic cardiovascular disease risk in adulthood. We will discuss the following: (i) adult cardiovascular outcomes in humans subjected to ELS, (ii) MatSep as an animal model of ELS as well as the limitations and advantages of this model in rodents and (iii) possible ELS-induced mechanisms that predispose individuals to greater cardiovascular risk. Overall, exposure to a behavioural stressor early in life sensitizes the response to a second stressor later in life, thus unmasking an exaggerated cardiovascular dysfunction that may influence quality of life and life expectancy in adulthood.

Early life stress sensitizes the renal and systemic sympathetic system in rats

We hypothesized that maternal separation (MS), an early life stress model, induces a sensitization of the sympathetic system. To test this hypothesis, we evaluated the renal and systemic sympathetic system in 12- to 14-wk-old male control or MS rats with the following parameters: 1) effect of renal denervation on conscious renal filtration capacity, 2) norepinephrine (NE) content in key organs involved in blood pressure control, and 3) acute systemic pressor responses to adrenergic stimulation or ganglion blockade. MS was performed by separating pups from their mothers for 3 h/day from day 2 to 14; controls were nonhandled littermates. Glomerular filtration rate (GFR) was examined in renal denervated (DnX; within 2 wk) or sham rats using I¹²⁵-iothalamate plasma clearance. MS-DnX rats showed significantly increased GFR compared with MS-SHAM rats (3.8 ± 0.4 vs. 2.4 ± 0.2 ml/min, respectively, P < 0.05), whereas DnX had no effect in controls, indicating that renal nerves regulate GFR in MS rats. NE content was significantly increased in organ tissues from MS rats (P < 0.05, n = 6-8), suggesting a sensitization of the renal and systemic sympathetic system. Conscious MS rats displayed a significantly greater increase in mean arterial pressure (MAP) in response to NE (2 μg/kg ip) and a greater reduction in MAP in response to mecamylamine (2 mg/kg ip, P < 0.05, n = 4) monitored by telemetry, indicating that MS rats exhibit exaggerated responses to sympathetic stimulation. In conclusion, these data indicate that MS sensitizes the renal and systemic sympathetic system ultimately impairing blood pressure regulation.

Short-term hypercaloric diet induces blunted aortic vasoconstriction and enhanced vasorelaxation via increased nitric oxide synthase 3 activity and expression in Dahl salt-sensitive rats

AIM

To elucidate the role of the O(2)(-), H(2)O(2) or NO pathways in aortic angiotensin (Ang)II-induced vasoconstriction in Dahl salt-sensitive (SS) rats compared with control SS-13(BN) rats on a normal or hypercaloric diet.

METHODS

Aortic function was assessed using wire myography in 16-week-old rats maintained on a normal diet or a 4-week hypercaloric diet. Nitric oxide synthase (NOS) activity and expression was determined by the conversion of radio-labelled arginine to citrulline and Western blot analysis respectively.

RESULTS

On normal diet, AngII-induced vasoconstriction was greater in SS than SS-13(BN) rats. Polyethylene glycol superoxide dismutase (PEG-SOD) reduced the aortic AngII response similarly in both strains on normal diet. Catalase blunted, whereas N(ω)-Nitro-L-arginine methyl ester (L-NAME) did not affect the AngII response in SS rats. In SS-13(BN) rats, catalase had no effect and L-NAME enhanced AngII response. On hypercaloric diet, aortic AngII responsiveness was reduced in SS but unaltered in SS-13(BN) rats compared with their normal diet counterparts. PEG-SOD reduced the AngII response in both rats on hypercaloric diet. Catalase treatment did not alter aortic AngII response, while L-NAME increased the response in SS rats on hypercaloric diet. In SS-13(BN) rats on hypercaloric diet, catalase reduced and L-NAME did not alter the AngII response. Furthermore, aortic endothelial-dependent vasorelaxation was increased in SS rats on hypercaloric diet compared with normal diet and aortic NOS3 activity and expression was increased.

CONCLUSION

A short-term hypercaloric diet induces a blunted vasoconstrictive and enhanced vasodilatory phenotype in SS rats, but not in SS-13(BN) rats, via reduced H(2)O(2) and increased NOS3 function.

Sex differences in the enhanced responsiveness to acute angiotensin II in growth-restricted rats: role of fasudil, a Rho kinase inhibitor

This study tested the hypothesis that Rho kinase contributes to the enhanced pressor response to acute angiotensin II in intact male growth-restricted and gonadectomized female growth-restricted rats. Mean arterial pressure (MAP) and renal function were determined in conscious animals pretreated with enalapril (250 mg/l in drinking water) for 1 wk to block the endogenous renin-angiotensin system and normalize blood pressure (baseline). Blood pressure and renal hemodynamics did not differ at baseline. Acute Ang II (100 ng·kg(-1)·min(-1)) induced a greater increase in MAP and renal vascular resistance and enhanced reduction in glomerular filtration rate in intact male growth-restricted rats compared with intact male controls (P < 0.05). Cotreatment with the Rho kinase inhibitor fasudil (33 μg·kg(-1)·min(-1)) significantly attenuated these hemodynamic changes (P < 0.05), but it did not abolish the differential increase in blood pressure above baseline, suggesting that the impact of intrauterine growth restriction on blood pressure in intact male growth-restricted rats is independent of Rho kinase. Gonadectomy in conjunction with fasudil returned blood pressure back to baseline in male growth-restricted rats, and yet glomerular filtration rate remained significantly reduced (P < 0.05). Thus, these data suggest a role for enhanced renal sensitivity to acute Ang II in the developmental programming of hypertension in male growth-restricted rats. However, inhibition of Rho kinase had no effect on the basal or enhanced increase in blood pressure induced by acute Ang II in the gonadectomized female growth-restricted rat. Therefore, these studies suggest that Rho kinase inhibition exerts a sex-specific effect on blood pressure sensitivity to acute Ang II in growth-restricted rats.

Early life stress induces renal dysfunction in adult male rats but not female rats

Maternal separation (MatSep) is a model of behavioral stress during early life. We reported that MatSep exacerbates ANG II-induced hypertension in adult male rats. The aims of this study were to determine whether exposure to MatSep in female rats sensitizes blood pressure to ANG II infusion similar to male MatSep rats and to elucidate renal mechanisms involved in the response in MatSep rats. Wistar Kyoto (WKY) pups were exposed to MatSep 3 h/day from days 2 to 14, while control rats remained with their mothers. ANG II-induced mean arterial pressure (MAP; telemetry) was enhanced in female MatSep rats compared with control female rats but delayed compared with male MatSep rats. Creatinine clearance (Ccr) was reduced in male MatSep rats compared with control rats at baseline and after ANG II infusion. ANG II infusion significantly increased T cells in the renal cortex and greater histological damage in the interstitial arteries of male MatSep rats compared with control male rats. Plasma testosterone was greater and estradiol was lower in male MatSep rats compared with control rats with ANG II infusion. ANG II infusion failed to increase blood pressure in orchidectomized male MatSep and control rats. Female MatSep and control rats had similar Ccr, histological renal analysis, and sex hormones at baseline and after ANG II infusion. These data indicate that during ANG II-induced hypertension, MatSep sensitizes the renal phenotype in male but not female rats.

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

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