Moving Forward From COVID-19: Bridging Knowledge Gaps in Maternal Health With a New Conceptual Model.

As the world faces the health crisis of a global pandemic-with healthcare protocols in overhaul, and patients and care teams experiencing unprecedented levels of stress and unpredictability-we predict that current knowledge gaps in maternal health will inevitably have a lasting impact on the health of women giving birth now and in the near future. Since we are decades away from closing the knowledge gaps we need filled today, we recommend shifting thinking toward a comprehensive conceptual model that merges knowledge of stress physiology, neurobiology, and pregnancy physiology. The model we present here, the , is an expansion of the Reactive Scope Model built upon the concept of Homeostasis and Allostasis.

The HPA Axis During the Perinatal Period: Implications for Perinatal Depression.

The transition to motherhood is characterized by some of the most pronounced endocrine changes a woman will experience in her lifetime. Unfortunately, matrescence is also a time in a woman's life when she is most susceptible to mental illness such as perinatal depression. A growing body of research has aimed to determine how key endocrine systems, such as the hypothalamic-pituitary-adrenal (HPA) axis, are involved in the dysregulation of perinatal mental health.

Neural Versus Gonadal GnIH: Are they Independent Systems? A Mini-Review.

Based on research in protochordates and basal vertebrates, we know that communication across the first endocrine axes likely relied on diffusion. Because diffusion is relatively slow, rapid responses to some cues, including stress-related cues, may have required further local control of axis outputs (e.g.

Endocannabinoid Signaling in the Stress Response of Male and Female Songbirds.

Endocannabinoid (eCB) signaling plays an important role in the stress response pathways of the mammalian brain, yet its role in the avian stress response has not been described. Understanding eCB signaling in avian species (such as the European starling, Sturnus vulgaris) allows a model system that exhibits natural attenuation of hypothalamic-pituitary-adrenal (HPA) responsiveness to stressors. Specifically, seasonally breeding birds exhibit the highest HPA activity during the breeding season and subsequently exhibit a robust HPA down-regulation during molt.

Stress, captivity, and reproduction in a wild bird species.

In seasonal species, glucocorticoid concentrations are often highest during the breeding season. However, the role of increased hypothalamic-pituitary-adrenal (HPA) activity in the regulation of reproduction remains poorly understood. Our study is the first, to our knowledge, to document reproductive consequences of a non-pharmacological hindrance to seasonal HPA fluctuations.

A consensus endocrine profile for chronically stressed wild animals does not exist.

Given the connection between chronic stress and health, there has been a growing emphasis on identifying chronically stressed wild animals, especially in relation to anthropogenic disturbances. There is considerable confusion, however, in how to identify chronically stressed wild animals, but the most common assumption is that measures of glucocorticoid (GC) function will increase. In an attempt to determine an "endocrine profile" of a chronically stressed wild animal, this review collected papers from the literature that measured baseline GC, stress-induced GC, measures of integrated GC, negative feedback, hypothalamic-pituitary-adrenal axis sensitivity, and/or body weight in chronically stressed animals.

Dynamic changes in brain aromatase activity following sexual interactions in males: where, when and why?

It is increasingly recognized that estrogens produce rapid and transient effects at many neural sites ultimately impacting physiological and behavioral endpoints. The ability of estrogens to acutely regulate cellular processes implies that their concentration should also be rapidly fine-tuned. Accordingly, rapid changes in the catalytic activity of aromatase, the limiting enzyme for estrogen synthesis, have been identified that could serve as a regulatory mechanism of local estrogen concentrations.

Acute stress differentially affects aromatase activity in specific brain nuclei of adult male and female quail.

The rapid and temporary suppression of reproductive behavior is often assumed to be an important feature of the adaptive acute stress response. However, how this suppression operates at the mechanistic level is poorly understood. The enzyme aromatase converts testosterone to estradiol in the brain to activate reproductive behavior in male Japanese quail (Coturnix japonica).

Sex differences in brain aromatase activity: genomic and non-genomic controls.

Aromatization of testosterone into estradiol in the preoptic area plays a critical role in the activation of male copulation in quail and in many other vertebrate species. Aromatase expression in quail and in other birds is higher than in rodents and other mammals, which has facilitated the study of the controls and functions of this enzyme. Over relatively long time periods (days to months), brain aromatase activity (AA), and transcription are markedly (four- to sixfold) increased by genomic actions of sex steroids.

Mineralocorticoid and glucocorticoid receptor mRNA expression in the brain of translocated chukar (Alectoris chukar).

Although translocation is an important conservation tool in the effort to create self-sustaining wild populations of threatened species, avian translocations have a high failure rate and causes for failure are poorly understood. While "stress" is considered to play a major role in translocation failure, the physiological changes associated with chronic stress resulting from translocation have been investigated only recently. Translocation results in chronic stress-induced alterations of stress response physiology in the chukar (Alectoris chukar) and in the present study we tested the hypothesis that changes in the hypothalamic-pituitary-adrenal axis (HPA) are correlated with changes in the brain, specifically at the level of the glucocorticoid and mineralocorticoid receptors (GR and MR, respectively) in the hippocampus and hypothalamus.

Combined effects of molt and chronic stress on heart rate, heart rate variability, and glucocorticoid physiology in European starlings.

Molt is an important life-history stage in avian species, but little is known about the effects of chronic stress during this period. Three weeks after the onset of molt, captive European starlings (Sturnus vulgaris) were exposed to 18 days of chronic stress, induced with four 30-minute randomized stressors presented daily. Birds showed no chronic-stress-induced changes in heart rate or heart rate variability when measured either during the middle of the day or at night.

Wild European starlings (Sturnus vulgaris) adjust to captivity with sustained sympathetic nervous system drive and a reduced fight-or-flight response.

Although research on wild species typically involves capture, handling, and some degree of captivity, few studies examine how these actions affect and/or alter the animal's underlying stress physiology. Furthermore, we poorly understand the immediate changes that occur as wild animals adjust to captive conditions. Most studies to date have investigated relatively long-term changes in the glucocorticoid response to an acute stressor, but immediate changes in the fight-or-flight response are relatively understudied in wild-caught species.

The Reactive Scope Model - a new model integrating homeostasis, allostasis, and stress.

Allostasis, the concept of maintaining stability through change, has been proposed as a term and a model to replace the ambiguous term of stress, the concept of adequately or inadequately coping with threatening or unpredictable environmental stimuli. However, both the term allostasis and its underlying model have generated criticism. Here we propose the Reactive Scope Model, an alternate graphical model that builds on the strengths of allostasis and traditional concepts of stress yet addresses many of the criticisms.

Stress and translocation: alterations in the stress physiology of translocated birds.

Translocation and reintroduction have become major conservation actions in attempts to create self-sustaining wild populations of threatened species. However, avian translocations have a high failure rate and causes for failure are poorly understood. While 'stress' is often cited as an important factor in translocation failure, empirical evidence of physiological stress is lacking.

Heart rate and heart-rate variability responses to acute and chronic stress in a wild-caught passerine bird.

The cardiovascular-stress response has been studied extensively in laboratory animals but has been poorly studied in naturally selected species. We determined the relative roles of the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS) in regulating stress-induced changes in heart rate (HR) in wild-caught European starlings (Sturnus vulgaris). In both heart-rate variability (HRV) analysis and receptor blockade (atropine and propranolol) experiments, baseline HR was controlled predominantly by the PNS, whereas the increase in HR resulting from acute restraint stress was controlled predominantly by the SNS.

Initial transference of wild birds to captivity alters stress physiology.

Maintaining wild animals in captivity has long been used for conservation and research. While often suggested that captivity causes chronic stress, impacts on the underlying stress physiology are poorly understood. We used wild-caught chukar (Alectoris chukar) as a model avian species to assess how the initial 10 days of captivity alters the corticosterone (CORT) secretory pathway.

Captive European starlings (Sturnus vulgaris) in breeding condition show an increased cardiovascular stress response to intruders.

European starlings (Sturnus vulgaris) alter their physiology and behavior between seasons, becoming territorial during the spring/summer and flocking during the fall/winter. We used captive male starlings in breeding (photostimulated to 18L : 6D) and nonbreeding (11L : 13D) conditions to determine whether changing physiology and behavior alters their reaction to crowding. One or five intruders entered a resident's cage without human disturbance.