Interactive effects of anthropogenic environmental drivers on endocrine responses in wildlife

Anthropogenic activity has created unique environmental drivers, which may interact to produce unexpected effects. My aim was to conduct a systematic review of the interactive effects of anthropogenic drivers on endocrine responses in non-human animals. The interaction between temperature and light can disrupt reproduction and growth by impacting gonadotropins, thyroid hormones, melatonin, and growth hormone. Temperature and endocrine disrupting compounds (EDCs) interact to modify reproduction with differential effects across generations. The combined effects of light and EDCs can be anxiogenic, so that light-at-night could increase anxiety in wildlife. Light and noise increase glucocorticoid release by themselves, and together can modify interactions between individuals and their environment. The literature detailing interactions between drivers is relatively sparse and there is a need to extend research to a broader range of taxa and interactions. I suggest that incorporating endocrine responses into Adverse Outcome Pathways would be beneficial to improve predictions of environmental effects.

Harbours as unique environmental sites of multiple anthropogenic stressors on fish hormonal systems

Fish development and acclimation to environmental conditions are strongly mediated by the hormonal endocrine system. In environments contaminated by anthropogenic stressors, hormonal pathway alterations can be detrimental for growth, survival, fitness, and at a larger scale for population maintenance. In the context of increasingly contaminated marine environments worldwide, numerous laboratory studies have confirmed the effect of one or a combination of pollutants on fish hormonal systems. However, this has not been confirmed in situ. In this review, we explore the body of knowledge related to the influence of anthropogenic stressors disrupting fish endocrine systems, recent advances (focusing on thyroid hormones and stress hormones such as cortisol), and potential research perspectives. Through this review, we highlight how harbours can be used as "in situ laboratories" given the variety of anthropogenic stressors (such as plastic, chemical, sound, light pollution, and invasive species) that can be simultaneously investigated in harbours over long periods of time.

Endocrine-disrupting potential and toxicological effect of para-phenylphenol on Daphnia magna

Several phenol derivatives are suspected endocrine disruptors and have received attention in risk assessment studies for several decades owing to the structural similarity between estrogens and phenolic compounds. We assessed the endocrine disrupting effect of the phenolic compound para-phenylphenol (PPP) through acute tests and evaluating chronic endpoints in an invertebrate model, Daphnia magna. Exposure of D. magna to PPP induced substantial adverse effects, namely, reduced fecundity, slowed growth rate, delayed first brood, and a reduction in neonate size. Furthermore, we investigated the mRNA expression of relevant genes to elucidate the mechanism of endocrine disruption by PPP. Exposure of D. magna to PPP induced the substantial downregulation of genes and markers related to reproduction and development, such as EcR-A, EcR-B, Jhe, and Vtg. Consequently, we demonstrated that PPP has an endocrine disrupting effect on reproduction and development in D. magna.

Young fecal transplantation mitigates the toxicity of perfluorobutanesulfonate and potently refreshes the reproductive endocrine system in aged recipients

The aging process leads to the gradual impairment of physiological functions in the elderly, making them more susceptible to the toxicity of environmental pollutants. In this study, aged zebrafish were first transplanted with the feces from young donors and subsequently exposed to perfluorobutanesulfonate (PFBS), an emerging persistent toxic pollutant. The interaction between young fecal transplant and PFBS inherent toxicity was investigated, focusing on reproductive performance and the underlying endocrine mechanism. The results showed that PFBS single exposure increased the percentage of primary oocytes in aged ovaries, implying a blockage of oogenesis. However, transplantation of young feces completely abolished the effects of PFBS and promoted oocyte growth, as inferred by the obviously lower percentage of primary oocytes, accompanied by a higher percentage of cortical-alveolar oocytes. Measurement of sex hormones found that PFBS significantly increased the blood concentration of estradiol and disrupted the balance of sex hormones in the elderly, which were, however, efficiently ameliorated by young fecal transplantation. Based on gene transcription along the hypothalamic-pituitary-gonadal axis, hierarchical clustering analysis showed similar profiles of the reproductive endocrine system between young zebrafish and their aged counterparts transplanted with young feces, implying that young fecal transplantation might refresh the endocrine system of aged recipients, regardless of PFBS exposure. The increased transcription levels of mRNAs encoding vitellogenin, activinBA, and membrane bound progestin receptors would cooperatively enhance the growth and maturation of oocytes in the ovaries of aged zebrafish receiving young fecal transplantation. Overall, the findings highlighted the potent efficacy of young fecal transplantation to improve the reproductive function of the elderly and to mitigate the endocrine disruption of an environmental pollutant. These findings are expected to broaden our understanding of the efficacy, mechanisms, and application of fecal transplantation.

[Retrospective analysis of the incidence rate of the population in the Republic of Tatarstan with diseases of the endocrine system]

Diseases of the endocrine system are an urgent medical and social problem in connection with their widespread prevalence and negative growth trend throughout the world; they often accompany other chronic diseases and can lead to disability. Aim: to study the trends in the structure and characteristics of the morbidity of the population in the Republic of Tatarstan with diseases of the endocrine system. The study was based on the materials of the official statistics in the Republic of Tatarstan for the period 2014-2019, the methods of descriptive statistics and linear regression analysis were used. The indicators of the primary morbidity and prevalence of the endocrine system diseases among various age groups in the Republic of Tatarstan were studied. The retrospective analysis of the incidence of the endocrine system diseases in the population in the Republic of Tatarstan indicates the formation of stable negative trends in the growth of the prevalence of thyroid diseases, diabetes and obesity among all the groups under study. There is an increase in the primary incidence and prevalence of thyroid diseases among children (growth rate in 2019 compared to 2014 of 198.6 and 50.1% respectively) and adolescents (growth rate of 244.9% and 114.3% respectively), as well as an increase in the prevalence of type 2 diabetes in these groups (growth rate of 500% and 269,2% respectively); an increase in both the primary incidence (growth rate of 200%) and the prevalence of hypothyroidism among children (growth rate of 183.5%), an increase in the prevalence of thyroiditis among adults (growth rate of 24.3%).The rate of increase in the primary incidence of obesity, over 6 years of observation, among children was 74.7%, among adolescents - 171.1%; among the adult population - 21.2%. To reverse negative trends in morbidity, we believe it is necessary to strengthen preventive work among all age groups to form healthy eating habits, maintain a normal body weight, take legislative decisions on mass prevention of iodine deficiency in endemic regions, as well as conduct some research aimed at assessing the impact of risk factors caused by the impact of endocrine disruptors on the health of the population of the Republic.

Human epidermal growth factor receptor-2 and endocrine resistance in hormone-dependent breast cancer

Endocrine therapies are the main treatment strategies for the clinical management of hormone-dependent breast cancer. Despite prolonged time to recurrence in the adjuvant setting and the initial clinical responses in the metastatic setting, many patients eventually encounter tumour relapse due to acquired resistance to these agents. Other patients experience a lack of tumour regression at the beginning of treatment indicating de novo resistance that significantly limits its efficacy in the clinic. There is compelling evidence that human epidermal growth factor receptor-2 (HER2) overexpression contributes to resistance to endocrine therapies in oestrogen receptor-positive (ER+) breast cancer. ER+/HER2+ tumours comprise about 10% of all breast cancer cases and about 60% of the whole set of HER2+ tumours. Most patients with primary ER+/HER2+ disease will receive antibody-based HER2-targeted therapy, but this is generally for no more than one year while endocrine treatment is usually for at least 5 years. A number of HER2-kinase inhibitors are also now in clinical use or in clinical trials, and the interaction of these with endocrine treatment may differ from that of antibody treatment. In this review article, we aim to summarise knowledge on molecular mechanisms of breast cancer resistance to endocrine therapies attributable to the impact of HER2 signalling on endocrine sensitivity, to discuss data from clinical trials addressing the role of HER2 in the development of endocrine resistance in the metastatic, neoadjuvant and adjuvant settings and to explore rational new therapeutic strategies.

Optimal hormonal regulation when stressor cues are imperfect

The endocrine system uses information about the environment and the individual's state to regulate circulating concentrations of hormones, and then those hormones, through receptor binding, cause changes in the phenotype. How quickly individuals can up- and down-regulate their hormones can affect baseline and elevated hormone levels and presumably affects how successfully individuals can cope with a varying environment. To respond to environmental change, individuals first need to perceive and process cues about the state of the environment. Individuals may receive imperfect cues about the environment due to perceptual errors, variation in cues, or inexperience with novel stressors. In this paper we use a mathematical model to ask how these imperfect cues should affect how individuals regulate their glucocorticoid concentrations. We find imperfect cues can lead to changes in hormone regulation with individuals generally having higher baseline and lower elevated hormone levels as environmental cues become less reliable. Informational constraints and physiological constraints appear to have generally additive effects, with informational constraints having less of an impact as physiological constraints increase. Our results highlight the different means by which imperfect information can affect hormone regulation. We find that mistakes caused by imperfect cues are commonly responsible for changes in average hormone levels, but imperfect cues also cause individuals to be slower and less certain in their updated estimates of the environmental state, which affects hormone regulation. We also demonstrate the separate effects of false positive and false negative cues and how these are shaped by the relative fitness consequences of baseline and stress-induced hormone levels. Our model shows how given our assumptions imperfect stressor cues should affect endocrine flexibility and regulation, and we hope provides a piece for future conversations and models of endocrine regulation.

Implications of endocrine-disrupting chemicals on polycystic ovarian syndrome: A comprehensive review

Polycystic ovarian syndrome (PCOS) is a complex multifactorial disorder of unknown pathogenesis in which genetic and environmental factors contribute synergistically to its phenotypic expressions. Endocrine-disrupting chemicals (EDCs), a group of widespread pollutants freely available in the environment and consumer products, can interfere with normal endocrine signals. Extensive evidence has shown that EDCs, environmental contributors to PCOS, can frequently induce ovarian and metabolic abnormalities at low doses. The current research on environmental EDCs suggests that there may be link between EDC exposure and PCOS, which calls for more human bio-monitoring of EDCs using highly sophisticated analytical techniques for the identification and quantification and to discover the underlying pathophysiology of the disease. This review briefly elaborated on the general etiology of PCOS and listed various epidemiological and experimental data from human and animal studies correlating EDCs and PCOS. This review also provides insights into various analytical tools and sample preparation techniques for biomonitoring studies for PCOS risk assessment. Furthermore, we highlight the role of metabolomics in disease-specific biomarker discovery and its use in clinical practice. It also suggests the way forward to integrate biomonitoring studies and metabolomics to underpin the role of EDCs in PCOS pathophysiology.

A New Perspective on Regulation of Pituitary Plasticity: The Network of SOX2-Positive Cells May Coordinate Responses to Challenge

Plasticity of function is required for each of the anterior pituitary endocrine axes to support alterations in the demand for hormone with physiological status and in response to environmental challenge. This plasticity is mediated at the pituitary level by a change in functional cell mass resulting from a combination of alteration in the proportion of responding cells, the amount of hormone secreted from each cell, and the total number of cells within an endocrine cell population. The functional cell mass also depends on its organization into structural and functional networks. The mechanisms underlying alteration in gland output depend on the strength of the stimulus and are axis dependent but in all cases rely on sensing of output of the functional cell mass and its regulation. Here, we present evidence that the size of pituitary cell populations is constrained and suggest this is mediated by a form of quorum sensing. We propose that pituitary cell quorum sensing is mediated by interactions between the networks of endocrine cells and hormone-negative SOX2-positive (SOX2+ve) cells and speculate that the latter act as both a sentinel and actuator of cell number. Evidence for a role of the network of SOX2+ve cells in directly regulating secretion from multiple endocrine cell networks suggests that it also regulates other aspects of the endocrine cell functional mass. A decision-making role of SOX2+ve cells would allow precise coordination of pituitary axes, essential for their appropriate response to physiological status and challenge, as well as prioritization of axis modification.

Waterborne exposure to avobenzone and octinoxate induces thyroid endocrine disruption in wild-type and thrαa-/- zebrafish larvae

Avobenzone and octinoxate are frequently used as organic ultraviolet filters, and these chemicals are widely detected in water. This study evaluated the potential of avobenzone and octinoxate to disrupt thyroid endocrine system in wild-type and thyroid hormone receptor alpha a knockout (thrαa^-/-) zebrafish embryo/larvae. Following a 120 h exposure to various concentrations of avobenzone and octinoxate, larvae mortality and developmental toxicity in wild-type and thrαa^-/- fish were assessed. Triiodothyronine (T3) and thyroxine (T4) levels as well as transcriptional levels of ten genes associated with the hypothalamus-pituitary-thyroid (HPT) axis were measured in wild-type fish. Significantly lower larvae survival rate in thrαa^-/- fish exposed to ≥3 μM avobenzone and octinoxate suggests that the thyroid hormone receptor plays a crucial role in the toxic effects of avobenzone and octinoxate. A significant increase in the deio2 gene level in avobenzone-exposed zebrafish supports the result of an increased ratio of T3 to T4. Significant decrease of T4 level with upregulation of trh, tshβ, and tshr genes indicates feedback in the hypothalamus and pituitary gland to maintain hormonal homeostasis. Our observation indicates that exposure to avobenzone and octinoxate affects the thyroid hormone receptor and the feedback mechanisms of the HPT axis. CLINICAL TRIALS REGISTRATION: Not applicable.

Long-term opioid treatment and endocrine measures in patients with cancer-related pain: a systematic review

OBJECTIVES

Opioid analgesics are the main stay for cancer pain management; however, long-term opioid treatment (L-TOT) may suppress the endocrine system. This systemic review aimed at investigating effects of L-TOT on the endocrine system in patients with cancer-related pain.

METHODS

A search on MEDLINE, EMBASE and Web of Science databases was performed. Inclusion criteria were clinical studies investigating endocrine measures in adult patients with cancer-related pain in L-TOT (≥4 weeks). Outcomes and quality of evidence were assessed.

RESULTS

A total of 252 abstracts were identified; out of which 247 were excluded and five cross-sectional studies were included and analyzed. L-TOT was associated with lower serum concentration levels of total- and free testosterone in males, follicular stimulating hormone in females, and luteinizing hormone in both sexes. Moreover, higher morphine equivalent daily doses (MEDDs) were correlated with higher levels of cortisol and lower levels of LH in both sexes, and lower levels of total- and free testosterone in males. Sexual dysfunction was associated with low sex hormone levels. Level of evidence was low/very low.

CONCLUSIONS

The studies identified demonstrated that patients with cancer-related pain in L-TOT may have gonadal hypofunction causing sexual dysfunction, which may be correlated with opioid dose level. In addition, high serum concentrations of cortisol were positively correlated with high opioid dose levels. However, the evidence was weak and further research is necessary. PROSPERO, ID-number: CRD42020213059.

[Research progress on cardiac developmental toxicity induced by environmental endocrine disruptors exposure]

Environmental endocrine disruptors (EDCs) are ubiquitous in the environment, and detectable amounts are found in humans worldwide. EDCs can interact with nuclear receptors such as estrogen receptor, which could interfere with the normal function of endocrine system, and further cause the pathological alterations in the tissues. This article summarizes several common types of EDCs in the environment, which caused cardiac function abnormalities, and morphological growth malformations in heart as well as its relevant mechanisms, including oxidative stress, inflammatory response, changes in signal transduction, expressions of transcriptional regulatory factors, which are related to cardiac development, receptor pathways and cell apoptosis etc., for the purpose of understanding the process of EDCs-induced cardiac developmental toxicity, and further providing scientific theoretical basis for figuring out the toxicity mechanism of EDCs and the prevention and treatment of cardiac diseases.

Identification of combinations of endocrine disrupting chemicals in household chemical products that require mixture toxicity testing

People are exposed to various chemicals contained in consumer products for which the risks are poorly characterized. There is growing evidence that exposure to endocrine disrupting chemicals (EDCs) through product use potentially affects development, behavior, and reproduction. However, limited information is available about common combinations of chemicals based on their appearance and potential health effects. The present study listed the ingredients contained in 11064 household chemical products from a publicly available database, and identified EDCs related to estrogenicity, androgenicity, thyroid hormone disruption, and changes in steroidogenesis. Association rule mining was applied to the dataset to identify frequent combinations of chemicals or commonly occurring EDCs contained in a single product. Among the target products, ingredient names were matched with 1241 chemical identifiers. A total of 293 chemicals were related to endocrine disruption, and nearly two-thirds of the products contained more than one of these chemicals. Cleaning products, synthetic detergents, fabric softeners, air fresheners, and deodorants have several hotspots for fragrances, isothiazolinones, glycol ethers, and parabens. The three most prevalent EDCs in household chemical products were added to act as fragrances and preservatives. The present study demonstrated that commonly occurring chemical combinations can be derived using an association rule mining algorithm. The results of this study will be useful in prioritizing chemical combinations and developing management plans for EDC mixture in consumer products.

Using alternative test methods to predict endocrine disruption and reproductive adverse outcomes: do we have enough knowledge?

Endocrine disrupting chemicals (EDCs) are a matter of great concern. They are ubiquitous in the environment, are considered harmful to humans and wildlife, yet remain challenging to identify based on current international test guidelines and regulatory frameworks. For a compound to be identified as an EDC within the EU regulatory system, a plausible link between an endocrine mode-of-action and an adverse effect outcome in an intact organism must be established. This requires in-depth knowledge about molecular pathways regulating normal development and function in animals and humans in order to elucidate causes for disease. Although our knowledge about the role of the endocrine system in animal development and function is substantial, it remains challenging to predict endocrine-related disease outcomes in intact animals based on non-animal test data. A main reason for this is that our knowledge about mechanism-of-action are still lacking for essential causal components, coupled with the sizeable challenge of mimicking the complex multi-organ endocrine system by methodological reductionism. Herein, we highlight this challenge by drawing examples from male reproductive toxicity, which is an area that has been at the forefront of EDC research since its inception. We discuss the importance of increased focus on characterizing mechanism-of-action for EDC-induced adverse health effects. This is so we can design more robust and reliable testing strategies using non-animal test methods for predictive toxicology; both to improve chemical risk assessment in general, but also to allow for considerable reduction and replacement of animal experiments in chemicals testing of the 21st Century.

Insights into toxicity of polychlorinated naphthalenes to multiple human endocrine receptors: Mechanism and health risk analysis

This study explored the combined disruption mechanism of polychlorinated naphthalenes (PCNs) on the three key receptors (estrogen receptor, thyroid receptor, and adrenoceptor) of the human endocrine system. The intensity of PCN endocrine disruption on these receptors was first determined using a molecular docking method. A comprehensive index of PCN endocrine disruption to human was quantified by analytic hierarchy process and fuzzy analysis. The mode of action between PCNs and the receptors was further identified to screen the molecular characteristics influencing PCN endocrine disruption through molecular docking and fractional factorial design. Quantitative structure-activity relationship (QSAR) models were established to investigate the toxic mechanism due to PCN endocrine disruption. The results showed that the lowest occupied orbital energy (E_LUMO) was the most important factor contributing to the toxicity of PCNs on the endocrine receptors, followed by the orbital energy difference (ΔE) and positive Millikan charge (q⁺). Furthermore, the strategies were formulated through adjusting the nutritious diet to reduce health risk for the workers in PCN contaminated sites and the effectiveness and feasibility were assessed by molecular dynamic simulation. The simulation results indicated that the human health risk caused by PCN endocrine disruption could be effectively decreased by nutritional supplementation. The binding ability between PCNs and endocrine receptors significantly declined (up to -16.45%) with the supplementation of vitamins (A, B₂, B₁₂, C, and E) and carotene. This study provided the new insights to reveal the toxic mechanism of PCNs on human endocrine systems and the recommendations on nutritional supplements for health risk reduction. The methodology and findings could serve as valuable references for screening of potential endocrine disruptors and developing appropriate strategies for PCN or other persistent organic pollution control and health risk management.

Vitamin D Endocrine System and COVID-19: Treatment with Calcifediol

The COVID-19 pandemic is the greatest challenge facing modern medicine and public health systems. The viral evolution of SARS-CoV-2, with the emergence of new variants with in-creased infectious potential, is a cause for concern. In addition, vaccination coverage remains in-sufficient worldwide. Therefore, there is a need to develop new therapeutic options, and/or to optimize the repositioning of drugs approved for other indications for COVID-19. This may include the use of calcifediol, the prohormone of the vitamin D endocrine system (VDES) as it may have potential useful effects for the treatment of COVID-19. We review the aspects associating COVID-19 with VDES and the potential use of calcifediol in COVID-19. VDES/VDR stimulation may enhance innate antiviral effector mechanisms, facilitating the induction of antimicrobial peptides/autophagy, with a critical modulatory role in the subsequent host reactive hyperinflammatory phase during COVID-19: By decreasing the cytokine/chemokine storm, regulating the renin–angiotensin–bradykinin system (RAAS), modulating neutrophil activity and maintaining the integrity of the pulmonary epithelial barrier, stimulating epithelial repair, and directly and indirectly decreasing the increased coagulability and prothrombotic tendency associated with severe COVID-19 and its complications. Available evidence suggests that VDES/VDR stimulation, while maintaining optimal serum 25OHD status, in patients with SARS-CoV-2 infection may significantly reduce the risk of acute respiratory distress syndrome (ARDS) and severe COVID-19, with possible beneficial effects on the need for mechanical ventilation and/or intensive care unit (ICU) admission, as well as deaths in the course of the disease. The pharmacokinetic and functional characteristics of calcifediol give it superiority in rapidly optimizing 25OHD levels in COVID-19. A pilot study and several observational intervention studies using high doses of calcifediol (0.532 mg on day 1 and 0.266 mg on days 3, 7, 14, 21, and 28) dramatically decreased the need for ICU admission and the mortality rate. We, therefore, propose to use calcifediol at the doses described for the rapid correction of 25OHD deficiency in all patients in the early stages of COVID-19, in association, if necessary, with the new oral antiviral agents.

Long-term exposure to environmental relevant triclosan induces reproductive toxicity on adult zebrafish and its potential mechanism

Triclosan (TCS) is widely used in personal care products and has become a contaminant ubiquitously found in the aquatic environment. It is reported exposure to triclosan can cause serious toxic effects on aquatic animals. However, the molecular mechanisms about long-term exposure to TCS-induced reproductive toxicity are not well elucidated. In the present study, adult zebrafish were exposed to TCS (2, 20 and 200 μg/L) for 150 days, and then the reproductive capacity assessment, steroid hormone and VTG quantitative measurement, histopathology observation and RNA sequencing analysis were performed to investigate the effects of TCS on its reproduction. The results indicated that long-term exposure to TCS causes the regulation disorder of the endocrine system, resulting in a reduction of the number of normal germ cells, and ultimately a decrease in the hatching rate and survival rate of offspring. This study revealed the toxic effects and contributed to our deep understanding about the potential disease of TCS exposure in the aquatic environment.

A review on advances in removal of endocrine disrupting compounds from aquatic matrices: Future perspectives on utilization of agri-waste based adsorbents

In the recent past, a class of emerging contaminants particularly endocrine disrupting compounds (EDCs) in the aquatic environment have gained a lot of attention. This is due to their toxic behaviour, affecting endocrine activities in humans as well as among aquatic animals. Presently, there are no regulations and discharge limits for EDCs to preclude their negative impact. Furthermore, the conventional treatment processes fail to remove EDCs efficiently. This necessitates the need for more research aimed at development of advanced alternative treatment methods which are economical, efficient, and sustainable. This paper focusses on the occurrence, fate, toxicity, and various treatment processes for removal of EDCs. The treatment processes (physical, chemical, biological and hybrid) have been comprehensively studied highlighting their advantages and disadvantages. Additionally, the use of agri-waste based adsorption technologies has been reviewed. The aim of this review article is to understand the prospect of application of agri-waste based adsorbents for efficient removal of EDCs. Interestingly, research findings have indicated that the use of these low-cost and abundantly available agri-waste based adsorbents can efficiently remove the EDCs. Furthermore, the challenges and future perspectives on the use of agri-waste based adsorbents have been discussed.

General Challenges and Recommendations for the Water Quality Criteria of Endocrine Disrupting Chemicals (EDCs)

Water quality criteria (WQC) play an important role in the environmental management of pollutants in different countries or institutions. It has been found that endocrine disrupting chemicals (EDCs) can potentially alter functions of the endocrine system and consequently cause adverse effects in aquatic organisms. Therefore, the complicated modes of action and mechanisms of EDCs should be carefully considered in WQC studies. For example, the research regarding the WQC derivation of EDCs should prioritize sensitive aquatic species in consideration of the WQC derivation. Second, the chronic toxicity of EDCs should be of utmost concern. In addition, the appropriate effects and endpoints of EDCs should be carefully selected for the WQC derivation. Moreover, it was pointed out that some new methods should be taken into consideration in the WQC studies of EDCs in the near future.

Passing on the exercise baton: What can endocrine patients learn from elite athletes?

As elite athletes demonstrate through the Olympic motto 'Citius, Altius, Fortius- Communiter', new performance records are driven forward by favourable skeletal muscle bioenergetics, cardiorespiratory, and endocrine system adaptations. At a recreational level, regular physical activity is an effective nonpharmacological therapy in the treatment of many endocrine conditions. However, the impact of physical exercise on endocrine function and how best to incorporate exercise therapy into clinical care are not well understood. Beyond the pursuit of an Olympic medal, elite athletes may therefore serve as role models for showcasing how exercise can help in the management of endocrine disorders and improve metabolic dysfunction. This review summarizes research evidence for clinicians who wish to understand endocrine changes in athletes who already perform high levels of activity as well as to encourage patients to exercise more safely. Herein, we detail the upper limits of athleticism to showcase the adaptability of human endocrine-metabolic-physiological systems. Then, we describe the growing research base that advocates the importance of understanding maladaptation to physical training and nutrition in males and females; especially the young. Finally, we explore the impact of physical activity in improving some endocrine disorders with guidance on how lessons can be taken from athletes training and incorporated into strategies to move more people more often.

Misaligned hormonal rhythmicity: Mechanisms of origin and their clinical significance

Rhythmic hormonal secretion is key for sustaining health. While a central pacemaker in the hypothalamus is the main driver of circadian periodicity, many hormones oscillate with different frequencies and amplitudes. These rhythms carry information about healthy physiological functions, while at the same time they must be able to respond to external cues and maintain their robustness against severe perturbations. Since endocrine disruptions can lead to hormonal misalignment and disease, understanding the clinical significance of these rhythms can help support diagnosis and disease management. While the misalignment of dynamic hormone profiles can be quantitatively analysed though statistical and computational techniques, mathematical modelling can provide fundamental understanding about the mechanisms underpinning endocrine rhythms, particularly around the question of what makes them robust to some perturbations but fragile to others. In this study, I will review the key challenges of understanding hormonal rhythm misalignment from a mathematical perspective, including their causes and clinical significance. By reviewing modelling examples of coupled endocrine axes, I will address the question of how perturbations in one endocrine axis propagate to another, leading to the more complex issue of disentangling the contribution of each endocrine system to a robust dynamic environment.

Effects of long-term exposure of norfloxacin on the HPG and HPT axes in juvenile common carp

Currently, there is a relatively lack of relevant research on the interference effect of quinolone antibiotics on the endocrine of aquatic animals. In this study, the toxicity of norfloxacin (NOR) on the endocrine system of juvenile common carp (Cyprinus carpio) was evaluated, as well as the hematocyte parameters. Specifically, two important endocrine axes were assessed: the hypothalamus-pituitary-thyroid (HPT) axis and hypothalamus-pituitary-gonadal (HPG) axis. Norfloxacin was used as a representative of quinolone antibiotics. According to the concentration of water pollution areas and considering the bad situation that may be caused by wastewater discharge, a control, 100 ng/L NOR, and 1 mg/L NOR treatment groups were set up. The juvenile carp, as the test animal, was subjected to an exposure experiment for 42 days. Thyroid hormones (T3 and T4) and related genes in HPT axis and sex hormones (11-ketotestosterone [11-KT] and progesterone [PROG]) and related genes in HPG axis and blood count are tested. It was found that the T4 iodine level and conversion process were enhanced after NOR treatment, which in turn led to the increase of T3 content and biological activity in the blood. One hundred nanograms per liter NOR can inhibit the level of sex hormones and inhibit the expression of HPG axis-related genes. In the 1 mg/L NOR treatment group, long-term exposure over a certain concentration range may lead to the development of adaptive mechanisms, making the changes in hormones and related genes insignificant. In conclusion, this study provides reference data for the endocrine interference of quinolone antibiotics on aquatic organisms, and has ecological significance for assessing the health of fish populations of quinolone antibiotics. However, the specific sites and mechanisms of action related to the effects of NOR on the endocrine system remain unclear and require further study.

Endocrine disruption by azole fungicides in fish: A review of the evidence

Azole fungicides are widely used chemicals in agriculture and medicine. Their antifungal activity involves inhibition of steroid biosynthesis via inhibition of several cytochrome p450 enzymes. Evidence is accumulating in fish species to suggest azole fungicides perturb multiple hormone signaling pathways. The objective of this review was to comprehensively review data for azole-mediated impacts on the teleost endocrine system. We emphasize aspects of azole-induced endocrine disruption in several fish species, with special focus on the hypothalamic-pituitary-gonadal (HPG), hypothalamus-pituitary-thyroid (HPT) and hypothalamic-pituitary-adrenal (HPA) axis. Histopathological, physiological, and molecular data suggest azole fungicides at environmentally relevant concentrations and above are endocrine disruptors in fish. Endocrine disruption has been well documented for some azoles (e.g., difenconazole, fadrozole, ketoconazole, tebuconazole, triadimefon), but there are little data for others (e.g., cyproconazole, expoxiconazole, imidazole, metoconazole, nocodazole) in fish, revealing a knowledge gap in our understanding of azole toxicity. Based upon literature, computational analyses of transcriptome responses revealed progesterone-mediated oocyte maturation, insulin signaling pathway, adrenergic signaling, and metabolism of angiotensinogen may be processes disrupted by azoles. However, hormonal regulation of the sympathetic nervous system and the cardiovascular system in response to azole exposure has yet to be investigated in fish. Recommendations for studies moving forward include focus on non-steroid endocrine pathways, mechanisms of neuroendocrine disruption, and transgenerational effects of azoles on fish. This critical review identifies knowledge gaps and future directions for environmental studies focused on the effects of azoles in aquatic species.