Basic Concepts and Hormonal Regulators of the Stress System

Heat Stress and Its Impact on Corpus Luteum (CL) Function and Reproductive Efficiency in Mammals: A Critical Review

Heat stress is considered as one of the most crucial environmental stressors affecting reproductive efficiency in mammals through modulation of the function of Corpus Luteum (CL) that plays a vital role in progesterone production and pregnancy maintenance. Therefore, this detailed systematic review seeks to bring forward the interdisciplinary perspectives on the impact of heat stress exposure on CL function regarding hormonal shift, luteal phase distortion and fertility receptivity. High temperatures are shown to impose oxidative stress, change blood perfusion within the CL, signal transduction which converts the signal from the signaling molecule into an intracellular reaction and impaired luteal activity. This review incorporates various scientific studies on these effects to different mammalian species concerning the associated physiological mechanisms. Besides this, it also considers the overall impact in warm stressed population in livestock breeding in the agricultural system as well as their conservation from a general perspective. Some of the prevention and control measures for heat related reproductive problems are also covered here, addressing the importance of finding the impact on the CL in order to put in place these interventions. This review may be used to inform future developments that may improve the CL function with regards to heat stress and possible solutions to help mammals reproduced under climate change tender environment and even rising temperatures globally.

Psychosocial Stress Trajectories Are Associated With Puberty Timing: Findings From a 7-Year Cohort in Chongqing, China

CONTEXT

Evidence for the associations between psychosocial stress PS related exposures and puberty timing are inconclusive. The PS of children has rarely been evaluated through repeated measurements.

OBJECTIVE

To evaluate the associations between PS trajectories and pubertal outcomes of girls and boys in a Chinese cohort (2015-2022).

METHODS

Pubertal outcomes of 732 girls and 688 boys were physically examined every 6 months. Stressful life events were repeatedly assessed 7 times. A group-based trajectory model was fitted for the optimum trajectories of total PS and PS from 5 sources. A Cox model adjusted for age, body mass index, and socioeconomic factors was used to evaluate the association.

RESULTS

Compared with the "low, gradual decline" trajectory, the "moderate, gradual decline" trajectory of total PS was associated with late menarche (hazard ratio [HR] 0.816, 95% CI 0.677-0.983), late pubic hair development (HR 0.729, 95% CI 0.609-0.872), and late axillary hair development (HR 0.803, 95% CI 0.661-0.975) in girls. Girls following the "high, rise then decline" trajectory of PS from family life demonstrated delayed axillary hair development (HR 0.752, 95% CI 0.571-0.990). For boys, the "high, rise then decline" trajectory of PS from academic adaptation (HR 0.670, 95% CI 0.476-0.945) and life adaptation (HR 0.642, 95% CI 0.445-0.925) was associated with late axillary hair development. Boys in the "moderate, gradual decline" trajectory of PS from peer relationships was at risk of early testicular development (HR 1.353, 95% CI 1.108-1.653).

CONCLUSION

Chronic PS may be associated with delayed onset of several pubertal signs in both girls and boys. It may also accelerate testicular development of boys, indicating its varying impact on pubertal timing during early and later stages.

Endocrine effects of heat exposure and relevance to climate change

Climate change is increasing both seasonal temperatures and the frequency and severity of heat extremes. As the endocrine system facilitates physiological adaptations to temperature changes, diseases with an endocrinological basis have the potential to affect thermoregulation and increase the risk of heat injury. The effect of climate change and associated high temperature exposure on endocrine axis development and function, and on the prevalence and severity of diseases associated with hormone deficiency or excess, is unclear. This Perspective summarizes current knowledge relating to the hormonal effects of heat exposure in species ranging from rodents to humans. We also describe the potential effect of high temperature exposures on patients with endocrine diseases. Finally, we highlight the need for more basic science, clinical and epidemiological research into the effects of heat on endocrine function and health; this research could enable the development of interventions for people most at risk, in the context of rising environmental temperatures.

Long-term, Dynamic Remodelling of the Corticotroph Transcriptome and Excitability After a Period of Chronic Stress

Chronic stress results in long-term dynamic changes at multiple levels of the hypothalamic-pituitary-adrenal (HPA) axis resulting in stress axis dysregulation with long-term impacts on human and animal health. However, the underlying mechanisms and dynamics of altered of HPA axis function, in particular at the level of pituitary corticotrophs, during a period of chronic stress and in the weeks after its cessation (defined as "recovery") are very poorly understood. Here, we address the fundamental question of how a period of chronic stress results in altered anterior pituitary corticotroph function and whether this persists in recovery, as well as the transcriptomic changes underlying this. We demonstrate that, in mice, spontaneous and corticotrophin-releasing hormone-stimulated electrical excitability of corticotrophs, essential for ACTH secretion, is suppressed for weeks to months of recovery following a period of chronic stress. Surprisingly, there are only modest changes in the corticotroph transcriptome during the period of stress, but major alterations occur in recovery. Importantly, although transcriptional changes for a large proportion of mRNAs follow the time course suppression of corticotroph excitability, many other genes display highly dynamic transcriptional changes with distinct time courses throughout recovery. Taken together, this suggests that chronic stress results in complex dynamic transcriptional and functional changes in corticotroph physiology, which are highly dynamic for weeks following cessation of chronic stress. These insights provide a fundamental new framework to further understand underlying molecular mechanisms as well approaches to both diagnosis and treatment of stress-related dysfunction of the HPA axis.

Causal effects of post-traumatic stress disorder on autoimmune thyroid disease: insights from mendelian randomization

Objective

The relationship between post-traumatic stress disorder (PTSD) and autoimmune thyroid disease (AITD) needs further evaluation. This study employs Mendelian randomization (MR) to investigate the causal correlations of PTSD with autoimmune thyroiditis (AIT) and Graves' disease (GD).

Methods

Datasets for PTSD, AIT, and GD were obtained from FinnGen. The exposure-outcome causal relationship was assessed using inverse variance weighted, MR-Egger, and weighted median. Horizontal pleiotropy was evaluated through the MR-Egger intercept, heterogeneity was examined using Cochran's Q test, and robustness was assessed via leave-one-out sensitivity analysis.

Results

MR analysis indicated no significant causal relationship between PTSD and AIT (OR 0.920, 95% CI 0.832 to 1.017, p = 0.103), but a potential increase in the risk of GD associated with PTSD (OR 1.056, 95% CI 1.008 to 1.105, p = 0.021). MR-Egger intercept showed no horizontal pleiotropy (p > 0.05), and Cochran's Q showed no heterogeneity (p > 0.05). Sensitivity analysis suggested the MR results were robust.

Conclusions

Evidence of an MR association between genetic liability to PTSD and an increased risk of GD were provided, but no evidence of association between PTSD and AIT. The findings indicate that individuals with PTSD may have an increased likelihood of developing GD, underscoring the importance of further research to comprehend the intricate interplay between PTSD and thyroid disorders.

Neuroendocrine disturbances in women with functional hypothalamic amenorrhea: an update and future directions

Functional hypothalamic amenorrhea (FHA) is one of the most common causes of both primary and secondary amenorrhea in women of reproductive age. It is characterized by chronic anovulation and the absence of menses that appear as a result of stressors such as eating disorders, excessive exercise, or psychological distress. FHA is presumed to be a functional disruption in the pulsatile secretion of hypothalamic gonadotropin-releasing hormone, which in turn impairs the release of gonadotropin. Hypoestrogenism is observed due to the absence of ovarian follicle recruitment. Numerous neurotransmitters have been identified which play an important role in the regulation of the hypothalamic-pituitary-ovarian axis and of which the impairment would contribute to developing FHA. In this review we summarize the most recent advances in the identification of contributing neuroendocrine disturbances and relevant contributors to the development of FHA.

Advances in electrochemical biosensor design for the detection of the stress biomarker cortisol

The monitoring of stress levels in humans has become increasingly relevant, given the recent incline of stress-related mental health disorders, lifestyle impacts, and chronic physiological diseases. Long-term exposure to stress can induce anxiety and depression, heart disease, and risky behaviors, such as drug and alcohol abuse. Biomarker molecules can be quantified in biological fluids to study human stress. Cortisol, specifically, is a hormone biomarker produced in the adrenal glands with biofluid concentrations that directly correlate to stress levels in humans. The rapid, real-time detection of cortisol is necessary for stress management and predicting the onset of psychological and physical ailments. Current methods, including mass spectrometry and immunoassays, are effective for sensitive cortisol quantification. However, these techniques provide only single measurements which pose challenges in the continuous monitoring of stress levels. Additionally, these analytical methods often require trained personnel to operate expensive instrumentation. Alternatively, low-cost electrochemical biosensors enable the real-time detection and continuous monitoring of cortisol levels while also providing adequate analytical figures of merit (e.g., sensitivity, selectivity, sensor response times, detection limits, and reproducibility) in a simple design platform. This review discusses the recent developments in electrochemical biosensor design for the detection of cortisol in human biofluids. Special emphasis is given to biosensor recognition elements, including antibodies, molecularly imprinted polymers (MIPs), and aptamers, as critical components of electrochemical biosensors for cortisol detection. Furthermore, the advantages and limiting factors of various electrochemical techniques and sensing in complex biofluid matrices are overviewed. Remarks on the current challenges and future perspectives regarding electrochemical biosensors for stress monitoring are provided, including matrix effects (pH dependence and biological interferences), wearability, and large-scale production.

What is the impact of stress on the onset and anti-thyroid drug therapy in patients with graves' disease: a systematic review and meta-analysis

BACKGROUND

The effect of stress on Graves' disease (GD) is controversial. Our purpose was to quantify the impacts of stress on patients with Graves' disease.

METHODS

Systematic searches of PubMed, MEDLINE, Embase, Web of Science, Scopus, Cochrane Library and PsycInfo were conducted from inception to 1 January 2023. Studies comparing the incidence of stressful life events (SLEs) that occurred before diagnosis and during drug therapy in cases diagnosed with GD and controls were included in the final analysis.

RESULTS

Nine case-control studies and four cohort studies enrolling 2892 participants (1685 [58%] patients) were included. Meta-analysis revealed a high and significant effect-size index in a random effect model (d = 1.81, P = 0.01), indicating that stress is an important factor in the onset of GD. The relationship between SLEs and GD was stronger in studies with higher proportions of female patients (β = 0.22, P < 0.01) and weaker in studies with older patients with GD (β =-0.62, P < 0.01). However, stress did not significantly affect the outcome of antithyroid drug therapy for GD (d = 0.32, P = 0.09).

CONCLUSIONS

The results of this meta-analysis suggest that stress is one of the environmental triggers for the onset of GD. Therefore, we recommend stress management assistance for individuals genetically susceptible to GD, especially for young females.

Modeling integrated stress, sleep, fear and neuroimmune responses: Relevance for understanding trauma and stress-related disorders

Sleep and stress have complex interactions that are implicated in both physical diseases and psychiatric disorders. These interactions can be modulated by learning and memory, and involve additional interactions with the neuroimmune system. In this paper, we propose that stressful challenges induce integrated responses across multiple systems that can vary depending on situational variables in which the initial stress was experienced, and with the ability of the individual to cope with stress- and fear-inducing challenges. Differences in coping may involve differences in resilience and vulnerability and/or whether the stressful context allows adaptive learning and responses. We provide data demonstrating both common (corticosterone, SIH and fear behaviors) and distinguishing (sleep and neuroimmune) responses that are associated with an individual's ability to respond and relative resilience and vulnerability. We discuss neurocircuitry regulating integrated stress, sleep, neuroimmune and fear responses, and show that responses can be modulated at the neural level. Finally, we discuss factors that need to be considered in models of integrated stress responses and their relevance for understanding stress-related disorders in humans.

The Neurobiological Links between Stress and Traumatic Brain Injury: A Review of Research to Date

Neurological dysfunctions commonly occur after mild or moderate traumatic brain injury (TBI). Although most TBI patients recover from such a dysfunction in a short period of time, some present with persistent neurological deficits. Stress is a potential factor that is involved in recovery from neurological dysfunction after TBI. However, there has been limited research on the effects and mechanisms of stress on neurological dysfunctions due to TBI. In this review, we first investigate the effects of TBI and stress on neurological dysfunctions and different brain regions, such as the prefrontal cortex, hippocampus, amygdala, and hypothalamus. We then explore the neurobiological links and mechanisms between stress and TBI. Finally, we summarize the findings related to stress biomarkers and probe the possible diagnostic and therapeutic significance of stress combined with mild or moderate TBI.

Stress-Induced Depression and Alzheimer's Disease: Focus on Astrocytes

Neurodegenerative diseases and depression are multifactorial disorders with a complex and poorly understood physiopathology. Astrocytes play a key role in the functioning of neurons in norm and pathology. Stress is an important factor for the development of brain disorders. Here, we review data on the effects of stress on astrocyte function and evidence of the involvement of astrocyte dysfunction in depression and Alzheimer's disease (AD). Stressful life events are an important risk factor for depression; meanwhile, depression is an important risk factor for AD. Clinical data indicate atrophic changes in the same areas of the brain, the hippocampus and prefrontal cortex (PFC), in both pathologies. These brain regions play a key role in regulating the stress response and are most vulnerable to the action of glucocorticoids. PFC astrocytes are critically involved in the development of depression. Stress alters astrocyte function and can result in pyroptotic death of not only neurons, but also astrocytes. BDNF-TrkB system not only plays a key role in depression and in normalizing the stress response, but also appears to be an important factor in the functioning of astrocytes. Astrocytes, being a target for stress and glucocorticoids, are a promising target for the treatment of stress-dependent depression and AD.

The Gut Microbiota-Brain Axis: A New Frontier on Neuropsychiatric Disorders

Alzheimer's disease (AD) is a progressive and incurable neurodegenerative disorder of integrative areas of the brain, characterized by cognitive decline and disability resulting in negative impacts on the family of the patients and the health care services worldwide. AD involves oxidative stress, neuroinflammation and accelerated apoptosis, accompanied by deposition of amyloid-β peptide plaques and tau protein-based neurofibrillary tangles in the central nervous system. Among the multiple factors that contribute to the onset and evolution of this disease, aging stands out. That is why the prevalence of this disease has increased due to the constant increase in life expectancy. In the hope of finding new, more effective methods to slow the progression of this disease, over the last two decades, researchers have promoted "omics"-based approaches that include the gut microbiota and their reciprocal interactions with different targets in the body. This scientific advance has also led to a better understanding of brain compartments and the mechanisms that affect the integrity of the blood-brain barrier. This review aims to discuss recent advances related to the gut-brain-microbiota axis in AD. Furthermore, considering that AD involves psychiatric symptoms, this review also focuses on the psychiatric factors that interact with this axis (an issue that has not yet been sufficiently addressed in the literature).