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

Global research trends on maternal separation paradigms as an early life stress model: A bibliometric analysis

Background

Maternal separation (MS) is an early life stress model that is often studied to determine how early life stress affects brain development and psychopathological adaptation. As society has developed, public health problems have become increasingly prominent, and this research area has attracted significant attention. However, to date, there has been no systematic bibliometric study on MS. The aim of this study was to analyze the trends and frontiers in MS using bibliometrics and provide a scientific reference to researchers in the field.

Methods

Utilizing VOSviewer, CiteSpace, and Microsoft Excel, examined data obtained from the WoSCC, which encompasses the years 2002-2021.

Results

In this bibliometric study, we analyzed 6209 articles related to MS authored by 24,174 researchers across 121 countries and regions and published in 2219 journals. The United States had the most publications (2,232, 35.95%) and both the United States and the United Kingdom had the highest h-index. Institutions in the United States and France had the most published articles and citations. Keyword clustering analysis revealed associations between MS and adverse early life experiences, the hypothalamic-pituitary-adrenal (HPA) axis, stress, gene expression, and depression.

Conclusions

This bibliometric analysis highlights the current research focus on the long-term effects of MS on emotional cognition, the HPA axis, epigenetic changes, and their links to gut microbiome imbalances. Future research may expand on these findings to investigate the underlying mechanisms and broader health and societal implications of MS. These results provide a comprehensive overview of the current research landscape in MS and offer valuable insights for researchers to guide future investigations in this field.

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.

Vascular aging and subclinical atherosclerosis: why such a "never ending" and challenging story in cardiology?

The true onset of atherosclerosis remains one of the biggest challenges for cardiologists. Is atheroma plaque development considered the earliest step of vascular aging? If so, when it starts? Before or after birth? If it starts before birth or early during childhood, it seems that Thomas Sydenham was right: "A man is as old as his arteries." Except disorganization of elastic fibers, less is known about the morphology of vascular aging and also about the molecular events influencing the age of arteries, arterial stiffness, and their role in the appearance of future complications. Cellular and molecular events responsible for the switch from physiologic to pathologic aging of human arteries are less known. Epigenetic, genetic, and environmental influences at the onset of early vascular aging (EVA) should specifically influence the process. This paper briefly reviews the controversial data regarding vascular aging with an emphasis on the less known facts about the morphology of EVA.

Psychosocial Factors and Hypertension: A Review of the Literature

Black people have the highest prevalence of hypertension in the United States. Evidence suggests that psychosocial factors increase the risks for hypertension and help to account for racial differences in this condition. This article reviews research on psychosocial factors and hypertension, and contextualizes the findings within a health disparities framework. A wide range of psychosocial factors contribute to hypertension but understanding remains limited about how these factors relate to each other and accumulate to contribute to hypertension disparities. Future research on psychosocial factors and hypertension needs to enhance the effectiveness of interventions to reduce hypertension risk in ethnic minority communities.

Neonatal maternal separation stress elicits lasting DNA methylation changes in the hippocampus of stress-reactive Wistar Kyoto rats

Early-life stress (ELS) can alter neurodevelopment in variable ways, ranging from producing deleterious outcomes to stress resilience. While most ELS studies focus on its harmful effects, recent work by our laboratory and others shows that ELS elicits positive effects in certain individuals. We exposed Wistar Kyoto (WKY) rats, known for a stress reactive, anxiety/depression-like phenotype, to maternal separation (MS), a model of ELS. MS exposure elicited anxiolytic and antidepressant behavioral effects as well as improved cardiovascular function in adult WKY offspring. This study interrogates an epigenetic mechanism (DNA methylation) that may confer the adaptive effects of MS in WKY offspring. We quantified global genome methylation levels in limbic brain regions of adult WKYs exposed to daily 180-min MS or neonatal handling from postnatal day 1-14. MS exposure triggered dramatic DNA hypermethylation specifically in the hippocampus. Next-generation sequencing methylome profiling revealed reduced methylation at intragenic sites within two key nodes of insulin signaling pathways: the insulin receptor and one of its major downstream targets, mitogen-activated protein kinase kinase kinase 5 (Map3k5). We then tested the hypothesis that enhancing DNA methylation in WKY rats would elicit adaptive changes akin to the effects of MS. Dietary methyl donor supplementation improved WKY rats' anxiety/depression-like behaviors and also improved cardiovascular measures, similar to previous observations following MS. Overall, these data suggest a potential molecular mechanism that mediates a predicted adaptive response, whereby ELS induces DNA methylation changes in the brain that may contribute to successful stress coping and adaptive physiological changes in adulthood.