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Elliott P Brooks Barbara Davis Center for Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado, USA

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Lori Sussel Barbara Davis Center for Diabetes, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado, USA

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Historic and emerging studies provide evidence for the deterioration of pancreatic α cell function and identity in diabetes mellitus. Increased access to human tissue and the availability of more sophisticated molecular technologies have identified key insights into how α cell function and identity are preserved in healthy conditions and how they become dysfunctional in response to stress. These studies have revealed evidence of impaired glucagon secretion, shifts in α cell electrophysiology, changes in α cell mass, dysregulation of α cell transcription, and α-to-β cell conversion prior to and during diabetes. In this review, we outline the current state of research on α cell identity in health and disease. Evidence in model organisms and humans suggests that in addition to β cell dysfunction, diabetes is associated with a fundamental dysregulation of α cell identity. Importantly, epigenetic studies have revealed that α cells retain more poised and open chromatin at key cell-specific and diabetes-dysregulated genes, supporting the model that the inherent epigenetic plasticity of α cells makes them susceptible to the transcriptional changes that potentiate the loss of identity and function seen in diabetes. Thus, additional research into the maintenance of α cell identity and function is critical to fully understanding diabetes. Furthermore, these studies suggest α cells could represent an alternative source of new β cells for diabetes treatment.

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Rachel K Meyer School of Nutritional Sciences and Wellness, University of Arizona, Tucson, Arizona, USA

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Frank A Duca School of Animal and Comparative Biomedical Sciences, College of Agricultural and Life Sciences, University of Arizona, Tucson, Arizona, USA
BIO5 Institute, University of Arizona, Tucson, Arizona, USA

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The gastrointestinal system is now considered the largest endocrine organ, highlighting the importance of gut-derived peptides and metabolites in metabolic homeostasis. Gut peptides are secreted from intestinal enteroendocrine cells in response to nutrients, microbial metabolites, and neural and hormonal factors, and they regulate systemic metabolism via multiple mechanisms. While extensive research is focused on the neuroendocrine effects of gut peptides, evidence suggests that several of these hormones act as endocrine signaling molecules with direct effects on the target organ, especially in a therapeutic setting. Additionally, the gut microbiota metabolizes ingested nutrients and fiber to produce compounds that impact host metabolism indirectly, through gut peptide secretion, and directly, acting as endocrine factors. This review will provide an overview of the role of endogenous gut peptides in metabolic homeostasis and disease, as well as the potential endocrine impact of microbial metabolites on host metabolic tissue function.

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Rui Gao Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK

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Samuel Acreman Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
Department of Physiology, Institute of Neuroscience and Physiology, Metabolic Research Unit, University of Gothenburg, Göteborg, Sweden

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Jinfang Ma Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK

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Fernando Abdulkader Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil

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Anna Wendt Department of Clinical Sciences Malmö, Islet Cell Exocytosis, Lund University Diabetes Centre, Lund University, Malmö, Sweden

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Quan Zhang Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
CNC - Center for Neuroscience and Cell Biology, CIBB - Centre for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal

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Glucagon is the principal glucose-elevating hormone that forms the first-line defence against hypoglycaemia. Along with insulin, glucagon also plays a key role in maintaining systemic glucose homeostasis. The cells that secrete glucagon, pancreatic α-cells, are electrically excitable cells and use electrical activity to couple its hormone secretion to changes in ambient glucose levels. Exactly how glucose regulates α-cells has been a topic of debate for decades but it is clear that electrical signals generated by the cells play an important role in glucagon secretory response. Decades of studies have already revealed the key players involved in the generation of these electrical signals and possible mechanisms controlling them to tune glucagon release. This has offered the opportunity to fully understand the enigmatic α-cell physiology. In this review, we describe the current knowledge on cellular electrophysiology and factors regulating excitability, glucose sensing, and glucagon secretion. We also discuss α-cell pathophysiology and the perspective of addressing glucagon secretory defects in diabetes for developing better diabetes treatment, which bears the hope of eliminating hypoglycaemia as a clinical problem in diabetes care.

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Emma Wilson Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
Simons Initiative for the Developing Brain, The University of Edinburgh, Edinburgh, UK

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Fiona J Ramage Department of Systems Medicine, School of Medicine, University of Dundee, Dundee, UK

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Kimberley E Wever Department of Anesthesiology, Pain and Palliative Care, Radboud University Medical Center, Nijmegen, The Netherlands

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Emily S Sena Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK

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Malcolm R Macleod Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK

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Gillian L Currie Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK

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In biomedicine and many other fields, there are growing concerns around the reproducibility of research findings, with many researchers being unable to replicate their own or others’ results. This raises important questions as to the validity and usefulness of much published research. In this review, we aim to engage researchers in the issue of research reproducibility and equip them with the necessary tools to increase the reproducibility of their research. We first highlight the causes and potential impact of non-reproducible research and emphasise the benefits of working reproducibly for the researcher and broader research community. We address specific targets for improvement and steps that individual researchers can take to increase the reproducibility of their work. We next provide recommendations for improving the design and conduct of experiments, focusing on in vivo animal experiments. We describe common sources of poor internal validity of experiments and offer practical guidance for limiting these potential sources of bias at different experimental stages, as well as discussing other important considerations during experimental design. We provide a list of key resources available to researchers to improve experimental design, conduct, and reporting. We then discuss the importance of open research practices such as study preregistration and the use of preprints and describe recommendations around data management and sharing. Our review emphasises the importance of reproducible work and aims to empower every individual researcher to contribute to the reproducibility of research in their field.

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Antonella Rosario Ramona Cáceres Laboratorio de Fisiopatología Ovárica, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU – CONICET Mendoza), Mendoza, Argentina
Facultad de Ingeniería y Facultad de Ciencias Médicas, Universidad de Mendoza, Mendoza, Argentina

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Fiorella Campo Verde Arboccó Laboratorio de Fisiopatología Ovárica, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU – CONICET Mendoza), Mendoza, Argentina

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María de los Ángeles Sanhueza Laboratorio de Fisiopatología Ovárica, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU – CONICET Mendoza), Mendoza, Argentina

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Daniela Alejandra Cardone Laboratorio de Fisiopatología Ovárica, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU – CONICET Mendoza), Mendoza, Argentina

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Graciela Beatriz Rodriguez Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, San Luis, Argentina

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Marilina Casais Laboratorio de Biología de la Reproducción (LABIR), Universidad Nacional de San Luis, San Luis, Argentina

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Adriana Soledad Vega Orozco Laboratorio de Biología de la Reproducción (LABIR), Universidad Nacional de San Luis, San Luis, Argentina

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Myriam Raquel Laconi Laboratorio de Fisiopatología Ovárica, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU – CONICET Mendoza), Mendoza, Argentina
Facultad de Ingeniería y Facultad de Ciencias Médicas, Universidad de Mendoza, Mendoza, Argentina

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Neuroactive steroids can rapidly regulate multiple physiological functions in the central and peripheral nervous systems. The aims of the present study were to determine whether allopregnanolone (ALLO), administered in low nanomolar and high micromolar concentrations, can: (i) induce changes in the ovarian progesterone (P4) and estradiol (E2) release; (ii) modify the ovarian mRNA expression of Hsd3b1 (3β-hydroxysteroid dehydrogenase, 3β-HSD)3β-, Akr1c3 (20α-hydroxysteroid dehydrogenase, 20α-HSD), and Akr1c14 (3α-hydroxy steroid oxidoreductase, 3α-HSOR)); and (iii) modulate the ovarian expression of progesterone receptors A and B, α and β estrogenic receptors, luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR). To further characterize ALLO peripheral actions, the effects were evaluated using a superior mesenteric ganglion–ovarian nervous plexus–ovary (SMG–ONP–O) and a denervated ovary (DO) systems. ALLO SMG administration increased P4 concentration in the incubation liquid by decreasing ovarian 20α-HSD mRNA, and it also increased ovarian 3α-HSOR mRNA expression. In addition, ALLO neural peripheral modulation induced an increase in the expression of ovarian LHR, PRA, PRB, and ERα. Direct ALLO administration to the DO decreased E2 and increased P4 concentration in the incubation liquid. The mRNA expression of 3β-HSD decreased and 20α-HSD increased. Further, ALLO in the OD significantly changed ovarian FSHR and PRA expression. This is the first evidence of ALLO’s direct effect on ovarian steroidogenesis. Our results provide important insights about how this neuroactive steroid interacts both with the PNS and the ovary, and these findings might help devise some of the pleiotropic effects of neuroactive steroids on female reproduction. Moreover, ALLO modulation of ovarian physiology might help uncover novel treatment approaches for reproductive diseases.

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Yasminye D Pettway Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA

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Diane C Saunders Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee, USA

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Marcela Brissova Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee, USA

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In commemoration of 100 years since the discovery of glucagon, we review current knowledge about the human α cell. Alpha cells make up 30–40% of human islet endocrine cells and play a major role in regulating whole-body glucose homeostasis, largely through the direct actions of their main secretory product – glucagon – on peripheral organs. Additionally, glucagon and other secretory products of α cells, namely acetylcholine, glutamate, and glucagon-like peptide-1, have been shown to play an indirect role in the modulation of glucose homeostasis through autocrine and paracrine interactions within the islet. Studies of glucagon’s role as a counterregulatory hormone have revealed additional important functions of the α cell, including the regulation of multiple aspects of energy metabolism outside that of glucose. At the molecular level, human α cells are defined by the expression of conserved islet-enriched transcription factors and various enriched signature genes, many of which have currently unknown cellular functions. Despite these common threads, notable heterogeneity exists amongst human α cell gene expression and function. Even greater differences are noted at the inter-species level, underscoring the importance of further study of α cell physiology in the human context. Finally, studies on α cell morphology and function in type 1 and type 2 diabetes, as well as other forms of metabolic stress, reveal a key contribution of α cell dysfunction to dysregulated glucose homeostasis in disease pathogenesis, making targeting the α cell an important focus for improving treatment.

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S Peña Center for Neurobiochemical studies in Endocrine Diseases, Laboratory of Neurobiochemistry, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile

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M Rubio Center for Neurobiochemical studies in Endocrine Diseases, Laboratory of Neurobiochemistry, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile

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C Vargas Center for Neurobiochemical studies in Endocrine Diseases, Laboratory of Neurobiochemistry, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile

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C Alanis Center for Neurobiochemical studies in Endocrine Diseases, Laboratory of Neurobiochemistry, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile

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AH Paredes Center for Neurobiochemical studies in Endocrine Diseases, Laboratory of Neurobiochemistry, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile

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Leukaemia inhibitory factor (LIF) is a cytokine belonging to the interleukin-6 family that is important at the reproductive level in the uterine implantation process. However, there is very little evidence regarding its effect at the ovarian level. The aim of this work was to study the local involvement of the LIF/LIFRβ system in follicular development and steroidogenesis in rat ovaries. To carry out this research, LIF/LIFR/GP130 transcript and protein levels were measured in fertile and sub-fertile rat ovaries, and in vitro experiments were performed to assess STAT3 activation. Then, in in vivo experiments, LIF was administered chronically and locally for 28 days to the ovaries of rats by means of an osmotic minipump to enable us to evaluate the effect on folliculogenesis and steroidogenesis. It was determined by quantitative polymerase chain reaction and western blot that LIF and its receptors are present in fertile and sub-fertile ovaries and that LIF varies during the oestrous cycle, being higher during the oestrus and meta/dioestrus stages. In addition to this, it was found that LIF can activate STAT3 pathways and cause pSTAT3 formation. It was also observed that LIF decreases the number and size of preantral and antral follicles without altering the number of atretic antral follicles and can increase the number of corpora lutea, with a notable increase in the levels of progesterone (P4). It is therefore possible to infer that LIF exerts an important effect in vivo on folliculogenesis, ovulation and steroidogenesis, specifically the synthesis of P4.

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Yang Chen School of Life Science, Xuzhou Medical University, Xuzhou, Jiangsu, China
Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Xin Li School of Life Science, Xuzhou Medical University, Xuzhou, Jiangsu, China

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Jing Zhang Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Mingjiao Zhang Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Salah Adlat Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Xiaodan Lu Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Dan Li Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Honghong Jin Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Chenhao Wang Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Zin Mar Oo Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Farooq Hayel Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Quangang Chen School of Life Science, Xuzhou Medical University, Xuzhou, Jiangsu, China

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Xufeng Han School of Life Science, Xuzhou Medical University, Xuzhou, Jiangsu, China

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Renjin Chen School of Life Science, Xuzhou Medical University, Xuzhou, Jiangsu, China

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Xuechao Feng Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Luqing Zhang Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Yaowu Zheng Transgenic Research Center, Northeast Normal University, Changchun, Jilin, China

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Obesity is caused by imbalanced energy intake and expenditure. Excessive energy intake and storage in adipose tissues are associated with many diseases. Several studies have demonstrated that vascular growth endothelial factor B (VEGFB) deficiency induces obese phenotypes. However, the roles of VEGFB isoforms VEGFB167 and VEGFB186 in adipose tissue development and function are still not clear. In this study, genetic mouse models of adipose-specific VEGFB167 and VEGFB186 overexpression (aP2-Vegfb167 tg/+ and aP2-Vegfb186 tg/+ ) were generated and their biologic roles were investigated. On regular chow, adipose-specific VEGFB186 is negatively associated with white adipose tissues (WATs) and positively regulates brown adipose tissues (BATs). VEGFB186 upregulates energy metabolism and metabolism-associated genes. In contrast, VEGFB167 has a nominal role in adipose development and function. On high-fat diet, VEGFB186 expression can reverse the phenotypes of VEGFB deletion. VEGFB186 overexpression upregulates BAT-associated genes and downregulates WAT-associated genes. VEGFB186 and VEGFB167 have very distinct roles in the regulation of adipose development and energy metabolism. As a key regulator of adipose tissue development and energy metabolism, VEGFB186 may be a target for obesity prevention and treatment.

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Jessica Milano-Foster Division of Animal Sciences, 245 Bond Life Sciences Center, 1201 Rollins Dr University of Missouri, Columbia, Missouri, USA

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Laura C Schulz Department of Obstetrics, Gynecology and Women’s Health, N610 Medical Sciences Building, Columbia, Missouri, USA

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Modeling preeclampsia remains difficult due to the nature of the disease and the unique characteristics of the human placenta. Members of the Hominidae superfamily have a villous hemochorial placenta that is different in structure from those of other therian mammals, including the mouse hemochorial placenta, making this common animal model less ideal for studying this disease. Human placental tissues delivered from pregnancies complicated by preeclampsia are excellent for assessing the damage the disease causes but cannot answer how or when the disease begins. Symptoms of preeclampsia manifest halfway through pregnancy or later, making it currently impossible to identify preeclampsia in human tissues obtained from an early stage of pregnancy. Many animal and cell culture models recapitulate various aspects of preeclampsia, though none can on its own completely capture the complexity of human preeclampsia. It is particularly difficult to uncover the cause of the disease using models in which the disease is induced in the lab. However, the many ways by which preeclampsia-like features can be induced in a variety of laboratory animals are consistent with the idea that preeclampsia is a two-stage disease, in which a variety of initial insults may lead to placental ischemia, and ultimately systemic symptoms. The recent development of stem cell-based models, organoids, and various coculture systems have brought in vitro systems with human cells ever closer to recapitulating in vivo events that lead to placental ischemia.

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Banrida Wahlang Department of Medicine, School of Medicine, Division of Gastroenterology, Hepatology & Nutrition, University of Louisville, Louisville, Kentucky, USA
UofL Superfund Research Center, University of Louisville, Louisville, Kentucky, USA
The Center for Integrative Environmental Health Sciences, University of Louisville, Louisville, Kentucky, USA

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Based on biological sex, the consequential health outcomes from exposures to environmental chemicals or toxicants can differ in disease pathophysiology, progression, and severity. Due to basal differences in cellular and molecular processes resulting from sexual dimorphism of organs including the liver and additional factors influencing ‘gene–environment’ interactions, males and females can exhibit different responses to toxicant exposures. Associations between environmental/occupational chemical exposures and fatty liver disease (FLD) have been well-acknowledged in human epidemiologic studies and their causal relationships demonstrated in experimental models. However, studies related to sex differences in liver toxicology are still limited to draw any inferences on sex-dependent chemical toxicity. The purpose of this review is to highlight the present state of knowledge on the existence of sex differences in toxicant-associated FLD (TAFLD), discuss potential underlying mechanisms driving these differences, implications of said differences on disease susceptibility, and emerging concepts. Chemicals of interest include various categories of pollutants that have been investigated in TAFLD, namely persistent organic pollutants, volatile organic compounds, and metals. Insight into research areas requiring further development is also discussed, with the objective of narrowing the knowledge gap on sex differences in environmental liver diseases. Major conclusions from this review exercise are that biological sex influences TAFLD risks, in part due to (i) toxicant disruption of growth hormone and estrogen receptor signaling, (ii) basal sex differences in energy mobilization and storage, and (iii) differences in chemical metabolism and subsequent body burden. Finally, further sex-dependent toxicological assessments are warranted for the development of sex-specific intervention strategies.

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