Role of Sex Steroids in β Cell Function, Growth, and Survival

Pancreatic islet adaptation in pregnancy and postpartum

Pancreatic islets, particularly insulin-producing β-cells, are central regulators of glucose homeostasis capable of responding to a variety of metabolic stressors. Pregnancy is a unique physiological stressor, necessitating the islets to adapt to the complex interplay of maternal and fetal-placental factors influencing the metabolic milieu. In this review we highlight studies defining gestational adaptation mechanisms within maternal islets and emerging studies revealing islet adaptations during the early postpartum and lactation periods. These include adaptations in both β and in 'non-β' islet cells. We also discuss insights into how gestational and postpartum adaptation may inform pregnancy-specific and general mechanisms of islet responses to metabolic stress and contribute to investigation of gestational diabetes.

Oestrogens, adipose tissues and environmental exposures influence obesity and diabetes across the lifecycle

Endogenous oestrogens regulate essential functions to include menstrual cycles, energy balance, adipose tissue distribution, pancreatic β-cell function, insulin sensitivity and lipid homeostasis. Oestrogens are a family of hormones which include oestradiol (E2), oestrone (E1) and oestriol (E3). Oestrogens function by binding and activating oestrogen receptors (ERs). Phytoestrogens are plant-derived compounds which exhibit oestrogenic-like activity and can bind to ERs. Phytoestrogens exert potential oestrogenic-like benefits; however, their effects are context-dependent and require cautious consideration regarding generalised health benefits. Xenoestrogens are synthetic compounds which have been determined to disrupt endocrine function through binding to ERs. Xenoestrogens enter the body through various routes and given their chemical structure they can accumulate, posing long-term health risks. Xenoestrogens interfere with endogenous oestrogens and their functions contributing to conditions like cancer, infertility, and metabolic disorders. Understanding the interplay between endogenous and exogenous oestrogens is critical in order to determine their potential health consequences and requires further investigation. This manuscript provides a summary of the role endogenous oestrogens have in regulating metabolic functions. Additionally, we discuss the impact phytoestrogens and synthetic xenoestrogens have on biological systems across various life stages. We highlight their mechanisms of action, potential benefits, risks and discuss the need for further research to bridge gaps in understanding and mitigate exposure-related health risks.

Disrupted RNA editing in beta cells mimics early-stage type 1 diabetes

A major hypothesis for the etiology of type 1 diabetes (T1D) postulates initiation by viral infection, leading to double-stranded RNA (dsRNA)-mediated interferon response and inflammation; however, a causal virus has not been identified. Here, we use a mouse model, corroborated with human islet data, to demonstrate that endogenous dsRNA in beta cells can lead to a diabetogenic immune response, thus identifying a virus-independent mechanism for T1D initiation. We found that disruption of the RNA editing enzyme adenosine deaminases acting on RNA (ADAR) in beta cells triggers a massive interferon response, islet inflammation, and beta cell failure and destruction, with features bearing striking similarity to early-stage human T1D. Glycolysis via calcium enhances the interferon response, suggesting an actionable vicious cycle of inflammation and increased beta cell workload.

Sex Differences in the Association Between AST/ALT and Incidence of Type 2 Diabetes in Japanese Patients with Nonalcoholic Fatty Liver Disease: A Retrospective Cohort Study

OBJECTIVES/INTRODUCTION

The purpose of the current study was to investigate the association between Aspartate Transaminase (AST)/Alanine transaminase(ALT) and type 2 diabetes (T2DM) in nonalcoholic fatty liver disease (NAFLD) patients and to determine whether there were sex differences.

METHODS

In the retrospective study, we collected data on NAFLD patients (1, 896 men and 465 women) at Murakami Memorial Hospital from 2004 to 2015. Data were stratified by sex to investigate the association between AST/ALT and T2DM incidence by sex. Multiple regression analysis, smooth curve fitting model and subgroup analysis were used to determine the correlation, non-linear relationship and threshold effect between AST/ALT and T2DM.

RESULTS

In our study, 157 men and 40 women developed T2DM at follow-up. After adjusting for risk factors, AST/ALT was significantly associated with T2DM in men with NAFLD but not in women with NAFLD. The risk of T2DM increased as the AST/ALT ratio decreased. Besides, in male NAFLD patients, AST/ALT showed a non-linear relationship with T2DM, with an inflection point value of 0.964. When the AST to ALT ratio was below the threshold (AST/ALT <0.964), AST/ALT was significantly negatively associated with T2DM (HR = 0.177, 95% CI 0.055-0.568; P = 0.0036). In contrast, when AST/ALT >0.964, no significant association was found (HR = 3.174, 95% CI 0.345-29.167; P = 0.3074). Moreover, subgroup analysis showed that GGT could alter the relationship between AST/ALT and T2DM. In the group with GGT ≤ 40, AST/ALT was strongly associated with T2DM (HR = 0.24, 95% CI 0.09-0.66; P = 0.0059).

CONCLUSIONS

These results suggested that there were sex differences in the association between AST/ALT and T2DM in NAFLD participants. A non-linear association between AST/ALT and T2DM was observed in males. AST/ALT in the normal GGT group (GGT ≤40) might better facilitate the early screening of T2DM.

Sex differences in energy metabolism: natural selection, mechanisms and consequences

Metabolic homeostasis operates differently in men and women. This sex asymmetry is the result of evolutionary adaptations that enable women to resist loss of energy stores and protein mass while remaining fertile in times of energy deficit. During starvation or prolonged exercise, women rely on oxidation of lipids, which are a more efficient energy source than carbohydrates, to preserve glucose for neuronal and placental function and spare proteins necessary for organ function. Carbohydrate reliance in men could be an evolutionary adaptation related to defence and hunting, as glucose, unlike lipids, can be used as a fuel for anaerobic high-exertion muscle activity. The larger subcutaneous adipose tissue depots in healthy women than in healthy men provide a mechanism for lipid storage. As female mitochondria have higher functional capacity and greater resistance to oxidative damage than male mitochondria, uniparental inheritance of female mitochondria may reduce the transmission of metabolic disorders. However, in women, starvation resistance and propensity to obesity have evolved in tandem, and the current prevalence of obesity is greater in women than in men. The combination of genetic sex, programming by developmental testosterone in males, and pubertal sex hormones defines sex-specific biological systems in adults that produce phenotypic sex differences in energy homeostasis, metabolic disease and drug responses.

Sex differences in type 2 diabetes: an opportunity for personalized medicine

Over the past several decades, substantial ground has been gained in understanding the biology of sex differences. With new mandates to include sex as a biological variable in NIH-funded research, greater knowledge is forthcoming on how sex chromosomes, sex hormones, and social and societal differences between sexes can affect the pathophysiology of health and disease. A detailed picture of how biological sex impacts disease pathophysiology will directly inform clinicians in their treatment approaches and challenge canonical therapeutic strategies. Thus, a profound opportunity to explore sex as a variable in personalized medicine now presents itself. While many sex differences are apparent in humans and have been described at length, we are only beginning to see how such differences impact disease progression, treatment efficacy, and outcomes in obesity, type 2 diabetes, and cardiovascular disease. Here, we briefly present the most salient and convincing evidence of sex differences in type 2 diabetes detection, diagnostics, disease course, and therapeutics. We then offer commentary on how this evidence can inform clinicians on how to approach the clinical workup and management of different patients with diabetes. Finally, we discuss some gaps that remain in the literature and propose several research questions to guide basic and translational researchers as they continue in this growing area of scientific exploration.

Gut feelings in the islets: The role of the gut microbiome and the FFA2 and FFA3 receptors for short chain fatty acids on β-cell function and metabolic regulation

Short-chain fatty acids (SCFAs) are biosynthesized via fermentation of polysaccharides by gastrointestinal microbiota and have been shown to have wide-reaching effects on almost all tissues, including the pancreatic islets. Historically, the effects of SCFAs have been attributed to their intracellular metabolism and function as energy sources, but the discovery of free fatty acid G protein-coupled receptors (GPCRs) in the 2000s suggested that many functional outcomes of SCFAs are receptor-mediated. The SCFA receptors FFA2/GPR43 and FFA3/GPR41 are expressed on β-cells, where they regulate glucose-dependent insulin secretion, making them attractive targets for treatment of diabetes and other metabolic disorders. Here, we provide an update on the current evidence regarding regulation of FFA2/FFA3 receptors by specific probiotic bacterial species within the gut microbiome that synthesize SCFAs. We also review the body of research regarding the FFA2- and FFA3 receptor-specific function of SCFAs on β-cells and discuss the somewhat controversial and opposing findings within these studies.

Transcriptome and secretome profiling of sensory neurons reveals sex differences in pathways relevant to insulin sensing and insulin secretion

Sensory neurons in the dorsal root ganglia (DRG) convey somatosensory and metabolic cues to the central nervous system and release substances from stimulated terminal endings in peripheral organs. Sex-biased variations driven by the sex chromosome complement (XX and XY) have been implicated in the sensory-islet crosstalk. However, the molecular underpinnings of these male-female differences are not known. Here, we aim to characterize the molecular repertoire and the secretome profile of the lower thoracic spinal sensory neurons and to identify molecules with sex-biased insulin sensing- and/or insulin secretion-modulating activity that are encoded independently of circulating gonadal sex hormones. We used transcriptomics and proteomics to uncover differentially expressed genes and secreted molecules in lower thoracic T5-12 DRG sensory neurons derived from sexually immature 3-week-old male and female C57BL/6J mice. Comparative transcriptome and proteome analyses revealed differential gene expression and protein secretion in DRG neurons in males and females. The transcriptome analysis identified, among others, higher insulin signaling/sensing capabilities in female DRG neurons; secretome screening uncovered several sex-specific candidate molecules with potential regulatory functions in pancreatic β cells. Together, these data suggest a putative role of sensory interoception of insulin in the DRG-islet crosstalk with implications in sensory feedback loops in the regulation of β-cell activity in a sex-biased manner. Finally, we provide a valuable resource of molecular and secretory targets that can be leveraged for understanding insulin interoception and insulin secretion and inform the development of novel studies/approaches to fathom the role of the sensory-islet axis in the regulation of energy balance in males and females.

Intrapancreatic fat, pancreatitis, and pancreatic cancer

Pancreatic cancer is typically detected at an advanced stage, and is refractory to most forms of treatment, contributing to poor survival outcomes. The incidence of pancreatic cancer is gradually increasing, linked to an aging population and increasing rates of obesity and pancreatitis, which are risk factors for this cancer. Sources of risk include adipokine signaling from fat cells throughout the body, elevated levels of intrapancreatic intrapancreatic adipocytes (IPAs), inflammatory signals arising from pancreas-infiltrating immune cells and a fibrotic environment induced by recurring cycles of pancreatic obstruction and acinar cell lysis. Once cancers become established, reorganization of pancreatic tissue typically excludes IPAs from the tumor microenvironment, which instead consists of cancer cells embedded in a specialized microenvironment derived from cancer-associated fibroblasts (CAFs). While cancer cell interactions with CAFs and immune cells have been the topic of much investigation, mechanistic studies of the source and function of IPAs in the pre-cancerous niche are much less developed. Intriguingly, an extensive review of studies addressing the accumulation and activity of IPAs in the pancreas reveals that unexpectedly diverse group of factors cause replacement of acinar tissue with IPAs, particularly in the mouse models that are essential tools for research into pancreatic cancer. Genes implicated in regulation of IPA accumulation include KRAS, MYC, TGF-β, periostin, HNF1, and regulators of ductal ciliation and ER stress, among others. These findings emphasize the importance of studying pancreas-damaging factors in the pre-cancerous environment, and have significant implications for the interpretation of data from mouse models for pancreatic cancer.

Exposure to per- and polyfluoroalkyl substances in early pregnancy, risk of gestational diabetes mellitus, potential pathways, and influencing factors in pregnant women: A nested case-control study

Although previous studies have reported an association between maternal serum perfluoroalkyl substance (PFAS) exposure and gestational diabetes mellitus (GDM) risk, results have been inconsistent. Few studies have focused on the combined effects of emerging and legacy PFASs on glucose homeostasis while humans are always exposed to multiple PFASs simultaneously. Moreover, the potential pathways by which PFAS exposure induces GDM are unclear. A total of 295 GDM cases and 295 controls were enrolled from a prospective cohort of 2700 pregnant women in Shanghai, China. In total, 16 PFASs were determined in maternal spot serum samples in early pregnancy. We used conditional logistic regression, multiple linear regression, and Bayesian kernel machine regression (BKMR) to examine individual and joint effects of PFAS exposure on GDM risk and oral glucose tolerance test outcomes. The mediating effects of maternal serum biochemical parameters, including thyroid and liver function were further assessed. Maternal perfluorooctanoic acid (PFOA) exposure was associated with an increased risk of GDM (odds ratio (OR) = 1.68; 95% confidence interval (95% CI): 1.10, 2.57), consistent with higher concentrations in GDM cases than controls. Based on mediation analysis, an increase in the free triiodothyronine to free thyroxine ratio partially explained the effect of this association. For continuous glycemic outcomes, positive associations were observed between several PFASs and 1-h and 2-h glucose levels. In BKMR, PFAS mixture exposure showed a positive trend with GDM incidence, although the CIs were wide. These associations were more pronounced among women with normal pre-pregnancy body mass index (BMI). Mixed PFAS congeners may affect glucose homeostasis by increasing 1-h glucose levels, with perfluorononanoic acid found to be a main contributor. Exposure to PFASs was associated with increased risk of GDM and disturbance in glucose homeostasis, especially in normal weight women. The PFAS-associated disruption of maternal thyroid function may alter glucose homeostasis.

Knockdown of lncRNA Meg3 delays the onset of puberty in female rats

This study investigated how lncRNA Meg3 affects the onset of puberty in female rats. We determined Meg3 expression in the hypothalamus-pituitary-ovary axis of female rats at the infancy, prepubertal, pubertal, and adult life stages, using quantitative reverse transcription polymerase chain reaction (qRT-PCR). We also assessed the effects of Meg3 knockdown on the expression levels of puberty-related genes and Wnt/β-catenin proteins in the hypothalamus, time of puberty onset, levels of reproductive genes and hormones, and ovarian morphology in female rats. Meg3 expression in the ovary varied significantly between prepuberty and puberty (P < 0.01). Meg3 knockdown decreased the expression of Gnrh, and Kiss1 mRNA (P < 0.05) and increased the expression of Wnt (P < 0.01) and β-catenin proteins (P < 0.05) in the hypothalamic cells. Onset of puberty in Meg3 knockdown rats was delayed compared to the control group (P < 0.05). Meg3 knockdown decreased Gnrh mRNA levels (P < 0.05) and increased Rfrp-3 mRNA levels (P < 0.05) in the hypothalamus. The serum concentrations of progesterone (P₄) and estradiol (E₂) of Meg3 knockdown rats were lower than those in the control animals (P < 0.05). Higher longitudinal diameter and ovary weight were found in Meg3 knockdown rats (P < 0.05). These findings suggest that Meg3 regulates the expression of Gnrh, Kiss-1 mRNA and Wnt/β-catenin proteins in the hypothalamic cells, and Gnrh, Rfrp-3 mRNA of the hypothalamus and the serum concentration of P₄ and E₂, and its knockdown delays the onset of puberty in female rats.

Menopausal hormone therapy and the risk of type 2 diabetes mellitus: Health Insurance Database in South Korea-based retrospective cohort study

OBJECTIVE

Menopausal hormone therapy (MHT) is known to reduce the incidence of type 2 diabetes mellitus (T2DM); however, since the Women's Health Initiative study, the types and doses of female hormones used for MHT have changed considerably. Therefore, this study was conducted to determine whether MHT, which is currently widely prescribed, increases the risk of T2DM.

METHOD

We performed a retrospective cohort study based on national health insurance data and cancer screening data from 2002 to 2019. We included the MHT group as postmenopausal women older than 40 years who used at least one MHT for at least 6 months between 2003 and 2011. We subclassified the MHT group into five categories; tibolone, combined estrogen plus progestin by the manufacturer (CEPM), oral estrogen, combined estrogen plus progestin by the physician (CEPP), and transdermal estrogen. We selected the non-MHT group as postmenopausal women who had never been prescribed MHT from 2002 to 2019. We compared the incidence of T2DM between the MHT group and the non-MHT group.

RESULTS

We enrolled 330,771 women in the MHT group and 798,550 women in the control group. T2DM was diagnosed in 15.2% of the non-MHT group, 16.6% of the tibolone group, 12.1% of the CEPM group, 16.6% of the oral estrogen group, 15.4% of the CEPP group, and 17% of the transdermal estrogen group. In Cox proportional hazard analysis adjusted for variable factors, tibolone, oral estrogen, CEPP, and transdermal estrogen increased the incidence of T2DM. In contrast, there was no change in the risk of T2DM in the CEPM group.

CONCLUSIONS

MHT, including tibolone, which is currently the most prescribed agent, increased the risk of T2DM; however, CEPM did not increase the risk of T2DM. Only tibolone increased the risk of T2DM in participants older than 70 years.

Menopause and diabetes

In the last 20 years, the prevalence of type 2 diabetes mellitus (T2DM) has tripled in adults aged 20-79 years, affecting more than 25% of people over 50 years of age and especially women during menopause. After the menopause transition, women gain weight, increasing abdominal fat and decreasing lean body mass, with a significant reduction in energy expenditure. Increased insulin resistance and hyperinsulinism characterize this period, aggravated by an increase in plasma proinflammatory cytokines and free fatty acids, and a state of relative hyperandrogenism. Previous recommendations systematically excluded women with T2DM from menopause hormone therapy (MHT); new evidence confirms that MHT significantly reduces the diagnosis of new-onset T2DM and may be beneficial in terms of glycemic control when used for menopause symptom management in patients with pre-existing T2DM. A comprehensive and individualized approach is considered the first line of management for women during this period, especially in T2DM patients or in women at risk of developing the disease. The objectives of this presentation are to review the etiopathogenic factors involved in the increased incidence of new cases of T2DM during menopause, the impact of menopause on T2DM and the role of MHT.

Metabolic parameters and thyroid hormones in relation to suicide attempts in patients with first-episode and drug-naive major depressive disorder with comorbid glucose disturbances: a large cross-sectional study

The factors associated with suicide attempts in major depressive disorder (MDD) patients with comorbid glucose disturbances remain unclear. To the best of our knowledge, this is the first study with a large sample size to examine risk factors of suicide attempts in first-episode drug-naïve (FEDN) MDD patients with comorbid glucose disturbances, including clinically relevant factors, metabolic parameters, and thyroid hormone levels. A total of 1718 FEDN MDD patients were enrolled. The Hamilton Depression Scale (HAMD), Hamilton Anxiety Scale (HAMA), and Positive and Negative Syndrome Scale (PANSS) were used to assess the clinical symptoms of patients. Fasting blood glucose, metabolic parameters, and thyroid hormone levels were measured. After controlling for HAMA and HAMD scores, the suicide attempt rate was 1.88 times higher in MDD patients with glucose disturbances than in MDD patients without glucose disturbances. Compared to non-suicide attempters, suicide attempters among the MDD patients with glucose disturbances had higher scores on HAMD and HAMA, PANSS positive symptoms, as well as higher levels of systolic and diastolic blood pressure, TC, LDL-C, thyroid stimulating hormone (TSH), TgAb, and thyroid peroxidases antibody (TPOAb). The combination of positive symptom score, HDL-C, systolic blood pressure, and marital status distinguished suicide attempters from non-suicide attempters. In addition, HAMA score, HAMD score, and TPOAb were associated with the number of suicide attempts in MDD patients with comorbid glucose disturbances. Our results suggest a high incidence of suicide attempts in MDD patients with comorbid glucose disturbances. Several clinically relevant factors, metabolic parameters, and thyroid hormone function have an impact on suicide attempts in MDD patients with comorbid glucose disturbances.

The potent contraceptive gestodene exerts insulinotropic effects through its a-ring reduced metabolites with intrinsic estrogen-like activity in pancreatic β-cells

PURPOSE

The contraceptive gestodene is a potent synthetic progestin used in several low-dose contraceptive formulations. Clinical studies reported a relationship between long-term use of combined oral contraceptives containing gestodene (GDN) and profound alterations in glucose metabolism in women. The observation that contraceptive synthetic progestins exert hormone-like effects other than their progestational activities, prompted us to investigate whether GDN may induce estrogen-like effects, even though GDN does not interact with estrogen receptors. The aim of this study was to investigate whether GDN affect pancreatic β-cell activity, directly or through its conversion to other bioactive metabolites.

METHODS

The effects of GDN and its two derivatives 3β,5α-tetrahydro-GDN and 3α,5α-tetrahydro-GDN on insulin 2 (Ins II) and glucokinase (Gk) expression and glucose-stimulated insulin secretion were determined in pancreatic islets from female rats.

RESULTS

Gestodene did exert significant effects on islet β-cells activity. The most striking finding was that 3β,5α-tetrahydro-GDN and 3α,5α-tetrahydro-GDN had greater stimulatory effects on Ins II and Gk expression than that observed with GDN, consistent with their effects on glucose-stimulated insulin secretion. The effects on gene expression induced by GDN-derivatives were abolished by ICI 182,780 and MPP. In addition, the presence of inhibitors of androgen and progestin-metabolizing enzymes eliminated gene expression induced by GDN. These results indicated that GDN is metabolized to A-ring reduced metabolites with estrogen-like activities and through this mechanism, GDN may affect β-cell activity.

CONCLUSIONS

Altogether, the data suggest that 19-nortestosterone-derived contraceptives such as GDN, possess insulinotropic effects through their conversion into metabolites with intrinsic estrogen-like activity in pancreatic β-cells.

The insulin signaling pathway a century after its discovery: Sexual dimorphism in insulin signaling

Since practically a century ago, the insulin pathway was discovered in both vertebrates and invertebrates, implying an evolutionarily ancient origin. After a century of research, it is now clear that the insulin signal transduction pathway is a critical, flexible and pleiotropic pathway, evolving into multiple anabolic functions besides glucose homeostasis. It regulates paramount aspects of organismal well-being like growth, longevity, intermediate metabolism, and reproduction. Part of this diversification has been attained by duplications and divergence of both ligands and receptors riding on a common general signal transduction system. One of the aspects that is strikingly different is its usage in reproduction, particularly in male versus female development and fertility within the same species. This review highlights sexual divergence in metabolism and reproductive tract differences, the occurrence of sexually "exaggerated" traits, and sex size differences that are due to the sexes' differential activity/response to the insulin signaling pathway.

Sex Differences in Glucose Homeostasis

Sexual dimorphism has been demonstrated to have an effect on various physiological functions. In this regard, researchers have investigated its impact on glucose homeostasis in both preclinical and clinical studies. Sex differences mainly arise from physiological factors such as sex hormones, body fat and muscle distribution, and sex chromosomes. The sexual dimorphism has also been studied in the context of diabetes. Reflecting the prevalence of the disease among the population, studies focusing on the sex difference in type 1 diabetes (T1D) are not common as the ones in type 2 diabetes (T2D). T1D is reported as the only major specific autoimmune disease that exhibits a male predominance. Clinical studies have demonstrated that impaired fasting glucose is more frequent in men whereas women more commonly exhibit impaired glucose tolerance. Understanding the sex difference in glucose homeostasis becomes more attractive when focusing on the findings that highlight sexual dimorphism on the efficacy or adverse effect profile of antidiabetic medications. Thus, in this chapter, we aimed to discuss the impact of sex on the glucose homeostasis both in health and in diabetes.

A Low Dose of Ouabain Alters the Metabolic Profile of Adult Rats Experiencing Intrauterine Growth Restriction in a Sex-Specific Manner

Intrauterine growth restriction (IUGR) increases the risk of type 2 diabetes mellitus (T2DM) and metabolic diseases. The pancreas of fetuses with IUGR is usually characterized by pancreatic dysplasia and reduced levels of insulin secretion caused by the diminished replication of β-cells. Previous studies showed that a low dose of ouabain could reduce the apoptosis of embryonic nephric cells during IUGR and partially restore the number of nephrons at birth. The rescued kidneys functioned well and decreased the prevalence of hypertension. Thus, we hypothesized that ouabain could rescue pancreatic development during IUGR and reduce the morbidity of T2DM and metabolic diseases. Maternal malnutrition was used to induce the IUGR model, and then a low dose of ouabain was administered to rats with IUGR during pregnancy. Throughout the experiment, we monitored the pattern of weight increase and evaluated the metabolic parameters in the offspring in different stages. Male, but not female, offspring in the IUGR group presented catch-up growth. Ouabain could benefit the impaired glucose tolerance of male offspring; however, this desirable effect was eliminated by aging. The insulin sensitivity was significantly impaired in male offspring with IUGR, but it was improved by ouabain, even during old age. However, in the female offspring, low birth weight appeared to be a beneficial factor even in old age; administering ouabain exacerbated these favorable effects. Our data suggested that IUGR influenced glucose metabolism in a sex-specific manner and ouabain treatment during pregnancy exerted strongly contrasting effects in male and female rats.

The interplay between diabetes mellitus and menopause: clinical implications

The menopausal transition is an impactful period in women's lives, when the risk of cardiovascular disease is accelerated. Similarly, diabetes mellitus profoundly impacts cardiovascular risk. However, the interplay between menopause and diabetes mellitus has not been adequately studied. The menopausal transition is accompanied by metabolic changes that predispose to diabetes mellitus, particularly type 2 diabetes mellitus (T2DM), as menopause results in increased risk of upper body adipose tissue accumulation and increased incidence of insulin resistance. Equally, diabetes mellitus can affect ovarian ageing, potentially causing women with type 1 diabetes mellitus and early-onset T2DM to experience menopause earlier than women without diabetes mellitus. Earlier age at menopause has been associated with a higher risk of T2DM later in life. Menopausal hormone therapy can reduce the risk of T2DM and improve glycaemic control in women with pre-existing diabetes mellitus; however, there is not enough evidence to support the administration of menopausal hormone therapy for diabetes mellitus prevention or control. This Review critically appraises studies published within the past few years on the interaction between diabetes mellitus and menopause and addresses all clinically relevant issues, such as the effect of menopause on the development of T2DM, and the management of both menopause and diabetes mellitus.

Influence of Gender in Diabetes Mellitus and Its Complication

In medicine, there is growing evidence that gender differences are important and lead to variations in the pathophysiology and treatment of many diseases with traits that appear to be particularly relevant in influencing the outcomes of many morbid forms. Today, the inclusion of gender in biomedical research, to improve the scientific quality and scientific relevance of knowledge, of technology is an increasingly present element precisely due to the practical implications that derive from it. Gender differences describe the biological variability between women and men, which is, in turn, related to differences in the information contained in sex chromosomes, the specific gene expression of autosomes linked to sex, the different number and quality of sex hormones, and their different effects on systems and organs, without neglecting the fact that each of the sexes has different target organs on which these hormones act. Additionally, both genders undergo metabolic changes throughout their lives, and this is especially true for women who show more dramatic changes due to their role in reproduction. Gender differences are not only the result of our genetic makeup but are also mixed with socio-cultural habits, behaviors, and lifestyles, differences between women and men, exposure to specific environmental influences, different food and lifestyle styles or stress, or different attitude in compliance with treatments and disease prevention campaigns. Gender differences also affect behavior throughout life, and physical changes can have implications for lifestyle, social roles, and mental health. Therefore, determinism and therapeutic outcome in chronic diseases are influenced by a complex combination of biological and environmental factors, not forgetting that there are many interactions of social and biological factors in women and men. This review will address the role of gender differences in the management of various forms of diabetes and its complications considering the different biological functions of hormones, the difference in body composition, physiological differences in glucose and fat metabolism, also considering the role of the microbiota. intestinal, as well as the description of gestational diabetes linked to possible pathophysiological events typical of reproduction.

Exercise mode influences post-exercise glucose sensitivity and insulin clearance in young, healthy males and females in a sex-dependent manner: A randomized control trial

Type 2 diabetes (T2D) risk is lower in females than males. It has been reported that females have greater pancreatic 𝛽-cell function than males, which may at least in part contribute to the T2D risk in females. 𝛽-cell function is influenced by exercise training; however, previous trials comparing 𝛽-cell function between the sexes have not included participants matched for training status. Furthermore, the acute effects of different modes of exercise on 𝛽-cell function, and whether sex inherently influences these effects, are largely unexamined. Males and females (12/sex) completed a 120-min oral glucose tolerance test (OGTT) at rest (CON) and following acute bouts of high-intensity interval exercise (HIIE), moderate intensity continuous (MIC) exercise, and low-load high-repetition (LLHR) resistance exercise to assess whether sex inherently influences baseline and/or post-exercise pancreatic function in the absence of pathology. We found no sex differences in basal pancreatic 𝛽-cell function. Females had greater basal insulin clearance following MIC exercise compared to males (p = 0.01) and males tended to have a higher potentiation ratio following HIIE (p = 0.07). Females also had lower glucose sensitivity following MIC exercise compared to HIIE (p = 0.007) and LLHR (p = 0.003). Insulin clearance during the OGTT was greater following HIIE as compared with CON and MIC exercise (p = 0.02). 2-H oral glucose insulin sensitivity was greater following LLHR compared to CON (p = 0.01). Acute bouts of different modes of exercise do not differentially influence 𝛽-cell function but do influence insulin clearance and insulin sensitivity. Therefore, sex and exercise mode interact to differentially influence insulin clearance and glucose sensitivity.

Gender differences in cardiometabolic health and disease in a cross-sectional observational obesity study

Background

Beyond the degree of adiposity, the pattern of fat distribution has a profound influence on cardiometabolic risk. It is unclear if sex differences in body fat distribution can potentially explain any sex differences in the prevalence of the metabolic syndrome (MetS) and in individual cardiometabolic risk factors among obese men and women.

Methods

In this cross-sectional analysis, 432 persons from the ongoing Obesity Weight Reduction Study (n = 356 obese, ØBMI 41 ± 8 kg/m², and 76 non-obese, ØBMI 25 ± 3 kg/m²), were included. The relations of sex to MetS prevalence and selected cardiometabolic risk factors were assessed using univariate and multivariate adjusted regression models.

Results

In crude analyses, %fat mass and the fat mass/lean mass ratio were significantly higher in women than in men, regardless of increasing obesity categories, from normal weight to grade-3-obesity. In contrast, markers of abdominal obesity, such as waist circumference and waist-to-hip ratio were higher in men than in women, despite similar BMI. The prevalence of the MetS was higher in obese men than in women (67.6 vs. 45.0%, p < 0.0001), particularly in younger individuals < 40 years (72.5 vs. 36.8%, p < 0.0001), but “metabolically healthy obesity” (BMI ≥ 30, no other NCEP ATPIII MetS component) was more common in women than in men (15.6 vs. 4.1%, p < 0.0001). After adjusting for age, %body fat and height, sex differences were observed for HDL-cholesterol (p < 0.001), triglycerides (p < 0.001), fasting glucose (p = 0.002), insulin and HOMA-IR levels (p < 0.001), ALAT (p < 0.001), adiponectin (p < 0.001), and sE-selectin (p = 0.005). In contrast, crude sex differences in other variables, such as leptin levels (68 ± 4 in obese women vs. 33 ± 2 µg/L in men, p < 0.0001), disappeared after accounting for differences in %body fat (least-squares means of leptin: 52 ± 4 vs. 55 ± 6 µg /L, p = 0.740). A logistic regression model adjusting for age and lifestyle factors revealed a lower risk of having MetS for women as compared to men (OR = 0.38[0.22–0.60]). That risk estimate did not materially alter after adding BMI to the model. In contrast, no statistically significant association between sex and MetS prevalence was observed after adding waist circumference and adiponectin to the model (OR = 1.41[0.59–3.36]).

Conclusions

Different body fat distribution patterns, particularly abdominal adiposity, adiponectin, and related biomarkers, may contribute to sex differences in cardiometabolic risk factors and to the prevalence of the MetS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-022-00416-4.

Paternally expressed gene 3 (Pw1/Peg3) promotes sexual dimorphism in metabolism and behavior

The paternally expressed gene 3 (Pw1/Peg3) is a mammalian-specific parentally imprinted gene expressed in stem/progenitor cells of the brain and endocrine tissues. Here, we compared phenotypic characteristics in Pw1/Peg3 deficient male and female mice. Our findings indicate that Pw1/Peg3 is a key player for the determination of sexual dimorphism in metabolism and behavior. Mice carrying a paternally inherited Pw1/Peg3 mutant allele manifested postnatal deficits in GH/IGF dependent growth before weaning, sex steroid dependent masculinization during puberty, and insulin dependent fat accumulation in adulthood. As a result, Pw1/Peg3 deficient mice develop a sex-dependent global shift of body metabolism towards accelerated adiposity, diabetic-like insulin resistance, and fatty liver. Furthermore, Pw1/Peg3 deficient males displayed reduced social dominance and competitiveness concomitant with alterations in the vasopressinergic architecture in the brain. This study demonstrates that Pw1/Peg3 provides an epigenetic context that promotes male-specific characteristics through sex steroid pathways during postnatal development.

Pw1/Peg3 is under parental specific epigenetic regulation. We propose that Pw1/Peg3 confers a selective advantage in mammals by regulating sexual dimorphism. To address this question, we examined the consequences of Pw1/Peg3 loss of function in mice in an age- and sex-dependent context and found that Pw1/Peg3 mutants display reduced sexual dimorphism in growth, metabolism and behaviors. Our findings support the intralocus sexual conflict model of genomic imprinting where it contributes in sexual differentiation. Furthermore, our observations provide a unifying role of sex steroid signaling as a common property of Pw1/Peg3 expressing stem/progenitor cells and differentiated endocrine cells, both of which remain proliferative in response to gonadal hormones in adult life.

Associations between serum copper, zinc, selenium level and sex hormones among 6-19 years old children and adolescents in NHANES 2013-2016

Copper, zinc, and selenium are essential trace elements for human and have important effects on sex hormones. There are few studies on the relationships between the three trace elements and sex hormones. Therefore, our study aimed to investigate the relationships between serum copper, zinc, selenium and testosterone, estradiol, SHBG using data from the National Health and Nutrition Examination Survey (NHANES) 2013-2016 in participants 6-19 years. 1097 participants were enrolled and stratified into male/female children and adolescents. Weighted linear regression models combined regression diagnosis were used to estimate the relationships between trace elements and sex hormones according to the different stratifications. Our results showed that copper was inversely associated with testosterone and estradiol but positively correlated with SHBG. Zinc had positive relationships with testosterone in male adolescents and female children but an inverse relationship with testosterone in female adolescents. Furthermore, a negative association was observed between zinc and SHBG. With the rise of selenium level, testosterone and estradiol were increased but SHBG was decreased. In general, this study used more standardized statistical methods to investigate the relationships between copper, zinc, selenium and testosterone, estradiol, SHBG. Further study should pay attention to some details in statistical methods.

Effect of Hypertension, Waist-to-Height Ratio, and Their Transitions on the Risk of Type 2 Diabetes Mellitus: Analysis from the China Health and Retirement Longitudinal Study

BACKGROUND

Diabetes is a major reason of death and disability worldwide and frequently coexists with hypertension and central obesity. This study is aimed at investigating the effects of hypertension, waist-to-height ratio (WHtR), and their dynamic transitions on type 2 diabetes mellitus (T2DM) onset among middle-aged and elderly people in China.

METHODS

We analyzed 9843 participants free of T2DM (average age, 59.04 ± 9.26 years) at baseline from the China Health and Retirement Longitudinal Study. We classified the participants into the following four categories based on hypertension and WHtR statuses: nonhypertensive with a normal WHtR (NHNW); hypertensive with a normal WHtR (HTNW); nonhypertensive with an elevated WHtR (NHEW); and hypertensive with an elevated WHtR (HTEW). By using a Cox proportional hazards regression model, we assessed whether hypertension, WHtR, and their transitions over time correlated with T2DM risk.

RESULTS

During the follow-up of 8 years, 1263 participants developed incident T2DM. The hazard ratio (HR) for T2DM was 1.48 (95% CI: 1.12, 1.97), 1.56 (95% CI: 1.27, 1.92), and 2.15 (95% CI: 1.74, 2.67) in the HTNW, NHEW, and HTEW groups, respectively, compared with the NHNW group after controlling for confounding factors. When stratified by statuses of hypertension and WHtR transitions, the participants who transitioned from HTNW to HTEW (HR = 1.98, 95% CI: 1.24-3.17), or NHEW to NHNW/HTNW (HR = 1.74, 95% CI: 1.14-2.65), or remained NHEW (HR = 1.42, 95% CI: 1.04-1.93), or NHEW to HTEW (HR = 2.40, 95% CI: 1.66-3.49), or remained HTEW (HR = 2.51, 95% CI: 1.87-3.37) during the follow-up period showed a higher T2DM risk than the consistently NHNW participants.

CONCLUSIONS

Being HTNW, NHEW or HTEW or occurring adverse transitions between those states was strongly associated with T2DM onset. Effectively warding off hypertension and central obesity or preventing their further aggravation may substantially decrease the T2DM risk.

Effects of empagliflozin on the expression of kisspeptin gene and reproductive system function in streptozotocin-induced diabetic male rats

One of the main health concerns of diabetes is testicular dysfunction and impairment of reproductive function and sperm quality which can cause male infertility. kisspeptin is a hypothalamic neuropeptide hormone that is involved in the regulation of energy metabolism, gonadotrophin-releasing hormone (GnRH), and reproductive function. In the present study, the therapeutic effects of empagliflozin (sodium-glucose co-transporter 2 inhibitors) on kisspeptin expression along with reproductive function were investigated in diabetic male Wistar rats. Diabetes was induced by a single dose injection of 60 mg/kg streptozotocin. Empagliflozin in doses of 10 and 25 mg/kg body weight was used for 8 weeks. Serum samples, testis, epididymis, and pancreas tissues were collected at the end of the experiments. Lipid profiles, oxidative stress markers, blood hormones, expression of kisspeptin along with pathological alterations of the testis were assayed using real-time PCR, biochemical, and histological technics. Data have shown that empagliflozin improved hyperglycemia, reproductive impairment, oxidative stress condition, and histopathological alterations of pancreatic and testis tissues in diabetic animals. It improved the serum levels of sex hormones, insulin, leptin, and the expression of kisspeptin in the testes tissues. Spermatogenesis is also improved in treated animals. Data indicated that the administration of empagliflozin can ameliorate symptoms of diabetes. It probably has promising antidiabetic potential and may improve the male infertility of diabetic subjects. To our knowledge, this is the first experimental evidence for the potential impact of empagliflozin on kisspeptin expression in diabetic male rats.

Effect of maternal body mass index on the steroid profile in women with gestational diabetes mellitus

OBJECTIVE

To explore the effect of maternal body mass index (BMI) on steroid hormone profiles in women with gestational diabetes mellitus (GDM) and those with normal glucose tolerance (NGT).

METHODS

We enrolled 79 women with NGT and 80 women with GDM who had a gestational age of 24-28 weeks. The participants were grouped according to their BMI. We quantified 11 steroid hormones profiles by liquid chromatography-tandem mass spectrometry and calculated the product-to-precursor ratios in the steroidogenic pathway.

RESULTS

Women with GDM and BMI<25kg/m² showed higher concentrations of dehydroepiandrosterone (DHEA) (p<0.001), testosterone (T) (p=0.020), estrone (E1) (p=0.010) and estradiol (E2) (p=0.040) and lower Matsuda index and HOMA-β than women with NGT and BMI<25kg/m². In women with GDM, concentrations of E1 (p=0.006) and E2 (p=0.009) declined, accompanied by reduced E2/T (p=0.008) and E1/androstenedione (A4) (p=0.010) in the BMI>25 kg/m² group, when compared to that in the BMI<25 kg/m² group. The values of E2/T and E1/A4 were used to evaluate the cytochrome P450 aromatase enzyme activity in the steroidogenic pathway. Both aromatase activities negatively correlated with the maternal BMI and positively correlated with the Matsuda index in women with GDM.

CONCLUSIONS

NGT women and GDM women with normal weight presented with different steroid hormone profiles. Steroidogenic pathway profiling of sex hormones synthesis showed a significant increase in the production of DHEA, T, E1, and E2 in GDM women with normal weight. Additionally, the alteration of steroid hormone metabolism was related to maternal BMI in women with GDM, and GDM women with overweight showed reduced estrogen production and decreased insulin sensitivity compared with GDM women with normal weight.

Gender Differences in the Context of Obstructive Sleep Apnea and Metabolic Diseases

The relationship between obstructive sleep apnea (OSA) and endocrine and metabolic disease is unequivocal. OSA, which is characterized by intermittent hypoxia and sleep fragmentation, leads to and exacerbates obesity, metabolic syndrome, and type 2 diabetes (T2D) as well as endocrine disturbances, such as hypothyroidism and Cushing syndrome, among others. However, this relationship is bidirectional with endocrine and metabolic diseases being considered major risk factors for the development of OSA. For example, polycystic ovary syndrome (PCOS), one of the most common endocrine disorders in women of reproductive age, is significantly associated with OSA in adult patients. Several factors have been postulated to contribute to or be critical in the genesis of dysmetabolic states in OSA including the increase in sympathetic activation, the deregulation of the hypothalamus-pituitary axis, the generation of reactive oxygen species (ROS), insulin resistance, alteration in adipokines levels, and inflammation of the adipose tissue. However, probably the alterations in the hypothalamus-pituitary axis and the altered secretion of hormones from the peripheral endocrine glands could play a major role in the gender differences in the link between OSA-dysmetabolism. In fact, normal sleep is also different between men and women due to the physiologic differences between genders, with sex hormones such as progesterone, androgens, and estrogens, being also connected with breathing pathologies. Moreover, it is very well known that OSA is more prevalent among men than women, however the prevalence in women increases after menopause. At the same time, the step-rise in obesity and its comorbidities goes along with mounting evidence of clinically important sex and gender differences. Metabolic and cardiovascular diseases, seen as a men's illness for decades, presently are more common in women than in men and obesity has a higher association with insulin-resistance-related risk factors in women than in men. In this way, in the present manuscript, we will review the major findings on the overall mechanisms that connect OSA and dysmetabolism giving special attention to the specific regulation of this relationship in each gender. We will also detail the gender-specific effects of hormone replacement therapies on metabolic control and sleep apnea.

Steroids, steroid associated substances and gestational diabetes mellitus

As gestational diabetes mellitus (GDM) is both a frequent and serious complication, steroid levels in pregnancy are extremely elevated and their role in pregnancy is crucial, this review focuses on the role of steroids and related substances in the GDM pathophysiology. Low SHBG levels are associated with insulin resistance and hyperinsulinemia, while also predicting a predisposition to GDM. Other relevant agents are placental hormones such as kisspeptin and CRH, playing also an important role beyond pregnancy, but which are synthesized here in smaller amounts in the hypothalamus. These hormones affect both the course of pregnancy as well as the synthesis of pregnancy steroids and may also be involved in the GDM pathophysiology. Steroids, whose biosynthesis is mainly provided by the fetal adrenal glands, placenta, maternal adrenal glands, and both maternal and fetal livers, are also synthesized in limited amounts directly in the pancreas and may influence the development of GDM. These substances involve the sulfated Δ5 steroids primarily acting via modulating different ion channels and influencing the development of GDM in different directions, mostly diabetogenic progesterone and predominantly anti-diabetic estradiol acting both in genomic and non-genomic way, androgens associated with IR and hyperinsulinemia, neuroactive steroids affecting the pituitary functioning, and cortisol whose production is stimulated by CRH but which suppresses its pro-inflammatory effects. Due to the complex actions of steroids, studies assessing their predominant effect and studies assessing their predictive values for estimating predisposition to GDM are needed.

Placental Endocrine Activity: Adaptation and Disruption of Maternal Glucose Metabolism in Pregnancy and the Influence of Fetal Sex

The placenta is an endocrine fetal organ, which secretes a plethora of steroid- and proteo-hormones, metabolic proteins, growth factors, and cytokines in order to adapt maternal physiology to pregnancy. Central to the growth of the fetus is the supply with nutrients, foremost with glucose. Therefore, during pregnancy, maternal insulin resistance arises, which elevates maternal blood glucose levels, and consequently ensures an adequate glucose supply for the developing fetus. At the same time, maternal β-cell mass and function increase to compensate for the higher insulin demand. These adaptations are also regulated by the endocrine function of the placenta. Excessive insulin resistance or the inability to increase insulin production accordingly disrupts physiological modulation of pregnancy mediated glucose metabolism and may cause maternal gestational diabetes (GDM). A growing body of evidence suggests that this adaptation of maternal glucose metabolism differs between pregnancies carrying a girl vs. pregnancies carrying a boy. Moreover, the risk of developing GDM differs depending on the sex of the fetus. Sex differences in placenta derived hormones and bioactive proteins, which adapt and modulate maternal glucose metabolism, are likely to contribute to this sexual dimorphism. This review provides an overview on the adaptation and maladaptation of maternal glucose metabolism by placenta-derived factors, and highlights sex differences in this regulatory network.

Altered Steroidome in Women with Gestational Diabetes Mellitus: Focus on Neuroactive and Immunomodulatory Steroids from the 24th Week of Pregnancy to Labor

Gestational diabetes mellitus (GDM) is a complication in pregnancy, but studies focused on the steroidome in patients with GDM are not available in the public domain. This article evaluates the steroidome in GDM+ and GDM- women and its changes from 24 weeks (± of gestation) to labor. The study included GDM+ (n = 44) and GDM- women (n = 33), in weeks 24-28, 30-36 of gestation and at labor and mixed umbilical blood after delivery. Steroidomic data (101 steroids quantified by GC-MS/MS) support the concept that the increasing diabetogenic effects with the approaching term are associated with mounting progesterone levels. The GDM+ group showed lower levels of testosterone (due to reduced AKR1C3 activity), estradiol (due to a shift from the HSD17B1 towards HSD17B2 activity), 7-oxygenated androgens (competing with cortisone for HSD11B1 and shifting the balance from diabetogenic cortisol towards the inactive cortisone), reduced activities of SRD5As, and CYP17A1 in the hydroxylase but higher CYP17A1 activity in the lyase step. With the approaching term, the authors found rising activities of CYP3A7, AKR1C1, CYP17A1 in its hydroxylase step, but a decline in its lyase step, rising conjugation of neuroinhibitory and pregnancy-stabilizing steroids and weakening AKR1D1 activity.

Sex differences in the association between suicide attempts and glucose disturbances in first-episode and drug naive patients with major depressive disorder

BACKGROUND

Glucose metabolism is related to depression, but the relationship between blood glucose and suicide attempts in patients with major depressive disorder (MDD) remains unclear. This large-scale sample explores the relationship between suicide attempts and fasting blood glucose, in addition to sex differences in first-episode and drug naive (FEDN) MDD patients.

METHODS

1718 FEDN MDD patients diagnosed for the first time were recruited, and their demographic data, clinical data, and blood glucose indicators were collected. 17-item Hamilton Depression Rating Scale (HAMD), 14-item Hamilton Anxiety Rating Scale (HAMA), and positive subscale of the Positive and Negative Syndrome Scale (PANSS) were used to assess their depression, anxiety and psychotic symptoms, respectively.

RESULTS

The depression, anxiety, psychotic symptoms and blood sugar levels of the suicide attempt group were higher than those of the non-suicide attempt group. Correlation analysis showed that blood glucose was significantly associated with suicide attempts in male and female patients. While binary logistic regression showed that blood glucose levels were significantly associated with suicide attempts in male patients, it showed that suicide attempts were not significantly associated with blood glucose levels in female patients.

LIMITATIONS

The main limitations are cross-sectional design and inability to control selection bias.

CONCLUSIONS

In male MDD patients, fasting blood glucose level is a potential biomarker of suicide attempt, which deserves attention to avoid suicide risk. However, in female patients, fasting blood glucose has no significant correlation to suicide attempts.

Role of High Voltage-Gated Ca2+ Channel Subunits in Pancreatic β-Cell Insulin Release. From Structure to Function

The pancreatic islets of Langerhans secrete several hormones critical for glucose homeostasis. The β-cells, the major cellular component of the pancreatic islets, secrete insulin, the only hormone capable of lowering the plasma glucose concentration. The counter-regulatory hormone glucagon is secreted by the α-cells while δ-cells secrete somatostatin that via paracrine mechanisms regulates the α- and β-cell activity. These three peptide hormones are packed into secretory granules that are released through exocytosis following a local increase in intracellular Ca2+ concentration. The high voltage-gated Ca2+ channels (HVCCs) occupy a central role in pancreatic hormone release both as a source of Ca2+ required for excitation-secretion coupling as well as a scaffold for the release machinery. HVCCs are multi-protein complexes composed of the main pore-forming transmembrane α1 and the auxiliary intracellular β, extracellular α2δ, and transmembrane γ subunits. Here, we review the current understanding regarding the role of all HVCC subunits expressed in pancreatic β-cell on electrical activity, excitation-secretion coupling, and β-cell mass. The evidence we review was obtained from many seminal studies employing pharmacological approaches as well as genetically modified mouse models. The significance for diabetes in humans is discussed in the context of genetic variations in the genes encoding for the HVCC subunits.

Increase in testosterone levels is related to a lower risk of conversion of prediabetes to manifest diabetes in prediabetic males

Background

Testosterone plays an important role in the regulation of glucose metabolism. While earlier studies have shown that it has a protective effect in males, unfavorable effects of testosterone on glucose metabolism have been reported in females; however, whether there is a sex-specific relationship between testosterone and glucose metabolism in patients with prediabetes has not been investigated in detail hitherto.

Methods

This cross-sectional analysis investigated 423 males and 287 females with diagnosed prediabetes. Detailed assessment of their metabolic profiles was performed, including a 2‑h oral glucose tolerance test (OGTT), HbA1c levels, calculation of insulin resistance with homeostatic model assessment for insulin resistance (HOMA-IR), assessment of lipid metabolism, anthropometric parameters and the fatty liver index (FLI). By using Spearman’s correlation test, we investigated the sex-specific relationship between testosterone and metabolism in the prediabetic individuals.

Results

In the present study, prediabetic females (mean age 58.6 years, confidence interval [CI: 57.6 y; 59.5 y]) were characterized by lower fasting plasma glucose levels (104.2 mg/dl [CI: 103.0 mg/dl; 105.4 mg/dl] vs. 106.9 mg/dl [CI: 106.0 mg/dl; 107.8 mg/dl]) and a lower FLI (49.5 [CI: 45.7; 53.2] vs. 58.8 [CI: 55.8; 61.8]), but presented with a higher risk of developing manifest type 2 diabetes in the next 10 years (FINDRISK score: 17.6 [CI: 17.1; 18.1] vs. 16.1 [CI: 15.7; 16.5]) when compared to prediabetic males (mean age: 58.04 years [CI: 57.0 y; 59.1 y]). Testosterone was negatively related to insulin resistance (HOMA-IR: Spearman’s ρ: −0.33, p < 0.01), 2‑h stimulated glucose levels during the OGTT (ρ = −0.18, p < 0.01), HbA1c levels (ρ = −0.13, p < 0.05), FLI and BMI in prediabetic males; however, no relationship between testosterone and metabolic parameters could be found in prediabetic females.

Conclusion

The increase of testosterone levels in males was related to a more favorable glucose metabolism, including lower HbA1c, lower stimulated glucose levels and higher insulin sensitivity; however, in prediabetic females, testosterone was not related to glucose metabolism.

Metabolic Adaptations to Pregnancy in Healthy and Gestational Diabetic Pregnancies: The Pancreas - Placenta Axis

Normal pregnancy is associated with increased insulin resistance as a metabolic adaptation to the nutritional demands of the placenta and fetus, and this is amplified in obese mothers. Insulin resistance is normally compensated for by an adaptive increase in pancreatic β-cell mass together with enhanced glucose-stimulated insulin release. Placentally-derived hormones and growth factors are central to the altered pancreatic morphology and function. A failure of β-cells to undergo adaptive change after the first trimester has been linked with gestational diabetes. In the pregnant mouse, an increase in β-cell replication contributes to a 2-3-fold increase in mass peaking in late gestation, depending on the proliferation of existing β-cells, the differentiation of resident progenitor β-cells, or islet cell transdifferentiation. Using mouse models and human studies placenta- and islet of Langerhans-derived molecules have been identified that are likely to contribute to the metabolic adaptations to pregnancy and whose physiology is altered in the obese, glucose-intolerant mother. Maternal obesity during pregnancy can create a pro-inflammatory environment that can disrupt the response of the β-cells to the endocrine signals of pregnancy and limit the adaptive changes in β-cell mass and function, resulting in an increased risk of gestational diabetes.

Deconstructing the origins of sexual dimorphism in sensory modulation of pancreatic β cells

The regulation of glucose-stimulated insulin secretion and glucose excursion has a sensory component that operates in a sex-dependent manner.

OBJECTIVE

Here, we aim to dissect the basis of the sexually dimorphic interaction between sensory neurons and pancreatic β cells and its overall impact on insulin release and glucose homeostasis.

METHODS

We used viral retrograde tracing techniques, surgical and chemodenervation models, and primary cell-based co-culture systems to uncover the biology underlying sex differences in sensory modulation of pancreatic β-cell activity.

RESULTS

Retrograde transsynaptic labeling revealed a sex difference in the density of sensory innervation in the pancreas. The number of sensory neurons emanating from the dorsal root and nodose ganglia that project in the pancreas is higher in male than in female mice. Immunostaining and confocal laser scanning microscopy confirmed the higher abundance of peri-islet sensory axonal tracts in the male pancreas. Capsaicin-induced sensory chemodenervation concomitantly enhanced glucose-stimulated insulin secretion and glucose clearance in male mice. These metabolic benefits were blunted when mice were orchidectomized prior to the ablation of sensory nerves. Interestingly, orchidectomy also lowered the density of peri-islet sensory neurons. In female mice, capsaicin treatment did not affect glucose-induced insulin secretion nor glucose excursion and ovariectomy did not modify these outcomes. Interestingly, same- and opposite-sex sensory-islet co-culture paradigms unmasked the existence of potential gonadal hormone-independent mechanisms mediating the male-female difference in sensory modulation of islet β-cell activity.

CONCLUSION

Taken together, these data suggest that the sex-biased nature of the sensory control of islet β-cell activity is a result of a combination of neurodevelopmental inputs, sex hormone-dependent mechanisms and the potential action of somatic molecules encoded by the sex chromosome complement.

Sexual hormones and diabetes: The impact of estradiol in pancreatic β cell

Diabetes is one of the most prevalent metabolic diseases and its incidence is increasing throughout the world. Data from World Health Organization (WHO) point-out that diabetes is a major cause of blindness, kidney failure, heart attacks, stroke and lower limb amputation and estimated 1.6 million deaths were directly caused by it in 2016. Population studies show that the incidence of this disease increases in women after menopause, when the production of estrogen is decreasing in them. Knowing the impact that estrogenic signaling has on insulin-secreting β cells is key to prevention and design of new therapeutic targets. This chapter explores the role of estrogen and their receptors in the regulation of insulin secretion and biosynthesis, proliferation, regeneration and survival in pancreatic β cells. In addition, delves into the genetic animal models developed and its application for the specific study of the different estrogen signaling pathways. Finally, discusses the impact of menopause and hormone replacement therapy on pancreatic β cell function.

Retinol-Binding Protein 4 Activates STRA6, Provoking Pancreatic β-Cell Dysfunction in Type 2 Diabetes

Pancreatic β-cell dysfunction plays a decisive role in the progression of type 2 diabetes. Retinol-binding protein 4 (RBP4) is a prominent adipokine in type 2 diabetes, although its effect on β-cell function remains elusive, and the underlying mechanisms are unknown. Here, we found that elevated circulating RBP4 levels were inversely correlated with pancreatic β-cell function in db/db mice across different glycemic stages. RBP4 directly suppressed glucose-stimulated insulin secretion (GSIS) in primary isolated islets and INS-1E cells in a dose- and time-dependent manner. RBP4 transgenic (RBP4-Tg) overexpressing mice showed a dynamic decrease of GSIS, which appeared as early as 8 weeks old, preceding the impairment of insulin sensitivity and glucose tolerance. Islets isolated from RBP4-Tg mice showed a significant decrease of GSIS. Mechanistically, we demonstrated that the stimulated by retinoic acid 6 (STRA6), RBP4's only known specific membrane receptor, is expressed in β-cells and mediates the inhibitory effect of RBP4 on insulin synthesis through the Janus kinase 2/STAT1/ISL-1 pathway. Moreover, decreasing circulating RBP4 level could effectively restore β-cell dysfunction and ameliorate hyperglycemia in db/db mice. These observations revealed a role of RBP4 in pancreatic β-cell dysfunction, which provides new insight into the diabetogenic effect of RBP4.

Allomyrina dichotoma larva extract attenuates free fatty acid-induced lipotoxicity in pancreatic beta cells

BACKGROUD/OBJECTIVES

Allomyrina dichotoma larva (ADL), one of the many edible insects recognized as future food resources, has a range of pharmacological activities. In a previous study, an ADL extract (ADLE) reduced the hepatic insulin resistance of high-fat diet (HFD)-induced diabetic mice. On the other hand, the associated molecular mechanisms underlying pancreatic beta-cell dysfunction remain unclear. This study examined the effects of ADLE on palmitate-induced lipotoxicity in a beta cell line of a rat origin, INS-1 cells.

MATERIALS/METHODS

ADLE was administered to high-fat diet treated mice. The expression of apoptosis-related molecules was measured by Western blotting, and reactive oxidative stress generation and nitric oxide production were measured by DCH-DA fluorescence and a Griess assay, respectively.

RESULTS

The administration of ADLE to HFD-induced diabetic mice reduced the hyperplasia, 4-hydroxynonenal levels, and the number of apoptotic cells while improving the insulin levels compared to the HFD group. Treatment of INS-1 cells with palmitate reduced insulin secretion, which was attenuated by the ADLE treatment. Furthermore, the ADLE treatment prevented palmitate-induced cell death in INS-1 cells and isolated islets by reducing the apoptotic signaling molecules, including cleaved caspase-3 and PARP, and the Bax/Bcl2 ratio. ADLE also reduced the levels of reactive oxygen species generation, lipid accumulation, and nitrite production in palmitate-treated INS-1 cells while increasing the ATP levels. This effect corresponded to the decreased expression of inducible nitric oxide synthase (iNOS) mRNA and protein.

CONCLUSIONS

ADLE helps prevent lipotoxic beta-cell death in INS-1 cells and HFD-diabetic mice, suggesting that ADLE can be used to prevent or treat beta-cell damage in glucose intolerance during the development of diabetes.

Molecular Insulin Actions Are Sexually Dimorphic in Lipid Metabolism

The increment in energy-dense food and low physical activity has contributed to the current obesity pandemic, which is more prevalent in women than in men. Insulin is an anabolic hormone that regulates the metabolism of lipids, carbohydrates, and proteins in adipose tissue, liver, and skeletal muscle. During obesity, nutrient storage capacity is dysregulated due to a reduced insulin action on its target organs, producing insulin resistance, an early marker of metabolic dysfunction. Insulin resistance in adipose tissue is central in metabolic diseases due to the critical role that this tissue plays in energy homeostasis. We focused on sexual dimorphism on the molecular mechanisms of insulin actions and their relationship with the physiology and pathophysiology of adipose tissue. Until recently, most of the physiological and pharmacological studies were done in males without considering sexual dimorphism, which is relevant. There is ample clinical and epidemiological evidence of its contribution to the establishment and progression of metabolic diseases. Sexual dimorphism is a critical and often overlooked factor that should be considered in design of sex-targeted therapeutic strategies and public health policies to address obesity and diabetes.

Letrozole Rat Model Mimics Human Polycystic Ovarian Syndrome and Changes in Insulin Signal Pathways

BACKGROUND The aim of this study was to explore whether letrozole and high-fat diets (HFD) can induce obese insulin-resistant polycystic ovary syndrome (PCOS) with all reproductive and metabolic phenotypes in a rat model. MATERIAL AND METHODS Twenty-four 3-week-old female Sprague-Dawley rats were randomized into 4 groups: control, Letrozole, HFD, and Letrozol+HFD. The PCOS model was induced by 12 weeks of Letrozole treatment (1 mg/kg p.o. dissolved in 0.5% CMC solutions once daily) and HFD. Ovarian morphology, estrous cyclicity, hormonal status, body weight, glucose and insulin tolerance, lipid profile, and insulin signaling pathway were investigated. RESULTS The rat model manifests anovulatory cycles and PCO morphology, increased body weight, elevated testosterone levels, abnormal glucose and lipid metabolism, and insulin resistance. The rat model also expresses significantly decreased phosphorylation of 6 essential signaling proteins - INSR, IRS, PI3K, AKT, ERK1, ERK2 - in the PI3K/AKT and MAPK/ERK pathways in the classic insulin-sensitive tissues (e.g., quadriceps femoris muscle, omentum majus, and liver), as well as non-classic target ovary tissues. Disrupted insulin signaling contributes to the decrease in insulin sensitivity and compensatory hyperinsulinemia in PCOS rats. CONCLUSIONS Continuous administration of letrozole and high-fat diets can induce PCOS, metabolic phenotypes, and disrupted activation of the insulin signaling pathway.

Excitotoxicity and Overnutrition Additively Impair Metabolic Function and Identity of Pancreatic β-Cells

A sustained increase in intracellular Ca²⁺ concentration (referred to hereafter as excitotoxicity), brought on by chronic metabolic stress, may contribute to pancreatic β-cell failure. To determine the additive effects of excitotoxicity and overnutrition on β-cell function and gene expression, we analyzed the impact of a high-fat diet (HFD) on Abcc8 knockout mice. Excitotoxicity caused β-cells to be more susceptible to HFD-induced impairment of glucose homeostasis, and these effects were mitigated by verapamil, a Ca²⁺ channel blocker. Excitotoxicity, overnutrition, and the combination of both stresses caused similar but distinct alterations in the β-cell transcriptome, including additive increases in genes associated with mitochondrial energy metabolism, fatty acid β-oxidation, and mitochondrial biogenesis and their key regulator Ppargc1a Overnutrition worsened excitotoxicity-induced mitochondrial dysfunction, increasing metabolic inflexibility and mitochondrial damage. In addition, excitotoxicity and overnutrition, individually and together, impaired both β-cell function and identity by reducing expression of genes important for insulin secretion, cell polarity, cell junction, cilia, cytoskeleton, vesicular trafficking, and regulation of β-cell epigenetic and transcriptional program. Sex had an impact on all β-cell responses, with male animals exhibiting greater metabolic stress-induced impairments than females. Together, these findings indicate that a sustained increase in intracellular Ca²⁺, by altering mitochondrial function and impairing β-cell identity, augments overnutrition-induced β-cell failure.

Diabetes in Menopause: Risks and Management

The aim of this review is to present, critically appraise and qualitatively synthesize current evidence on the risk of type 2 diabetes mellitus (T2DM) development during menopause, the management of climacteric symptoms in women with T2DM and the management of T2DM in postmenopausal women. Menopause represents the end of reproductive life in women, as a result of ovarian aging. It is characterized by substantial decrease in the endogenous oestrogen concentrations and it is accompanied by alterations in body weight, adipose tissue distribution and energy expenditure, as well as insulin secretion, insulin sensitivity and activity that can predispose to the development of T2DM, independently of, and additively to, aging. Many women in midlife experience climacteric symptoms, including hot flushes and night sweats, resulting in an indication to receive Hormone Replacement Treatment (HRT). HRT has a favourable effect on glucose homeostasis both in women without and with T2DM. The latter was considered in the past as a cardiovascular disease (CVD) equivalent, which would suggest that women with the disease should not receive HRT. However, nowadays evidence exists to support an individualized approach of women based on their CVD risk, as some women with T2DM may be excellent candidates for HRT. Regarding T2DM management for women in menopause, lifestyle intervention, including diet and exercise, constitutes its cornerstone. However, most of these women will eventually require pharmacologic therapy. The most suitable agents should be selected according to their metabolic, cardiovascular and bone effects, taking into consideration the specific characteristics and comorbidities of each postmenopausal woman.

Sex Differences Across the Lifespan: A Focus on Cardiometabolism

Women's health and sex differences research remain understudied. In 2016, to address the topic of sex differences, the Center for Women' s Health Research (CWHR) at the University of Colorado (cwhr@ucdenver.edu) held its inaugural National Conference, "Sex Differences Across the Lifespan: A Focus on Metabolism" and published a report summarizing the presentations. Two years later, in 2018, CWHR organized the 2nd National Conference. The research presentations and discussions from the 2018 conference also addressed sex differences across the lifespan with a focus on cardiometabolism and expanded the focus by including circadian physiology and effects of sleep on cardiometabolic health. Over 100 participants, including basic scientists, clinicians, policymakers, advocacy group leaders, and federal agency leadership participated. The meeting proceedings reveal that although exciting advances in the area of sex differences have taken place, significant questions and gaps remain about women's health and sex differences in critical areas of health. Identifying these gaps and the subsequent research that will result may lead to important breakthroughs.

Sex differences in metabolic regulation and diabetes susceptibility

Gender and biological sex impact the pathogenesis of numerous diseases, including metabolic disorders such as diabetes. In most parts of the world, diabetes is more prevalent in men than in women, especially in middle-aged populations. In line with this, considering almost all animal models, males are more likely to develop obesity, insulin resistance and hyperglycaemia than females in response to nutritional challenges. As summarised in this review, it is now obvious that many aspects of energy balance and glucose metabolism are regulated differently in males and females and influence their predisposition to type 2 diabetes. During their reproductive life, women exhibit specificities in energy partitioning as compared with men, with carbohydrate and lipid utilisation as fuel sources that favour energy storage in subcutaneous adipose tissues and preserve them from visceral and ectopic fat accumulation. Insulin sensitivity is higher in women, who are also characterised by higher capacities for insulin secretion and incretin responses than men; although, these sex advantages all disappear when glucose tolerance deteriorates towards diabetes. Clinical and experimental observations evidence the protective actions of endogenous oestrogens, mainly through oestrogen receptor α activation in various tissues, including the brain, the liver, skeletal muscle, adipose tissue and pancreatic beta cells. However, beside sex steroids, underlying mechanisms need to be further investigated, especially the role of sex chromosomes, fetal/neonatal programming and epigenetic modifications. On the path to precision medicine, further deciphering sex-specific traits in energy balance and glucose homeostasis is indeed a priority topic to optimise individual approaches in type 2 diabetes prevention and treatment.

Early weaning induces short- and long-term effects on pancreatic islets in Wistar rats of both sexes

KEY POINTS

The World Health Organization recommends exclusive breastfeeding until 6 months of age as an important strategy to reduce child morbidity and mortality. Studies have associated early weaning with the development of obesity and type 2 diabetes in adulthood. In our model, we demonstrated that early weaning leads to increased insulin secretion in adolescent males and reduced insulin secretion in adult offspring. Early weaned males exhibit insulin resistance in skeletal muscle. Early weaning did not change insulin signalling in the muscle of female offspring. Taking into account that insulin resistance is one of the primary factors for the development of type 2 diabetes mellitus, this work demonstrates the importance of breastfeeding in the fight against this disease.

ABSTRACT

Early weaning (EW) leads to short- and long-term obesity and diabetes. This phenotype is also observed in experimental models, in which early-weaned males exhibit abnormal insulinaemia in adulthood. However, studies regarding the effect of EW on pancreatic islets are rare. We investigated the mechanisms by which glycaemic homeostasis is altered in EW models through evaluations of insulin secretion and its signalling pathway in offspring. Lactating Wistar rats and their pups were divided into the following groups: non-pharmacological EW (NPEW): mothers were wrapped with an adhesive bandage on the last 3 days of lactation; pharmacological EW (PEW): mothers received bromocriptine to inhibit prolactin (1 mg/kg body mass/day) on the last 3 days of lactation; and control (C): pups underwent standard weaning at PN21. Offspring of both sexes were euthanized at PN45 and PN180. At PN45, EW males showed higher insulin secretion (vs. C). At PN170, PEW males exhibited hyperglycaemia in an oral glucose tolerance test (vs. C and NPEW). At PN180, EW male offspring were heavier; however, both sexes showed higher visceral fat. Insulin secretion was lower in EW offspring of both sexes. Males from both EW groups had lower glucokinase in islets, but unexpectedly, PEW males showed higher GLUT2, than did C. EW males exhibited lower insulin signalling in muscle. EW females exhibited no changes in these parameters compared with C. We demonstrated distinct alterations in the insulin secretion of EW rats at different ages. Despite the sex dimorphism in insulin secretion in adolescence, both sexes showed impaired insulin secretion in adulthood due to EW.

Implicating androgen excess in propagating metabolic disease in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) has been traditionally perceived as a reproductive disorder due to its most common presentation with menstrual dysfunction and infertility. However, it is now clear that women with PCOS are at increased risk of metabolic dysfunction, from impaired glucose tolerance and type 2 diabetes mellitus to nonalcoholic fatty liver disease and cardiovascular disease. PCOS is characterised by androgen excess, with cross-sectional data showing that hyperandrogenism is directly complicit in the development of metabolic complications. Recent studies have also shown that C11-oxy _C19 androgens are emerging to be clinically and biochemically significant in PCOS, thus emphasising the importance of understanding the impact of both classic and C11-oxy _C19 androgens on women's health. Here we discuss androgen metabolism in the context of PCOS, and dissect the role played by androgens in the development of metabolic disease through their effects on metabolic target tissues in women.