Extranuclear Actions of the Androgen Receptor Enhance Glucose-Stimulated Insulin Secretion in the Male

May Patients Receiving GLP-1 Agonists Be at Lower Risk of Prostate Cancer Aggressiveness and Progression?

INTRODUCTION

GLP-1 receptor agonists are valuable therapeutic agents for managing obesity and type 2 diabetes. The link between prostate cancer and obesity was described. The modulation of incretin hormone-dependent pathways may decrease the prostate cancer aggressiveness and progression.

OBJECTIVES

The purpose of this study was to review and summarize the literature on the role of GLP-1 agonists in prostate cancer.

MATERIAL & METHODS

We performed a scoping literature review of PubMed from January 2002 to February 2025. Search terms included "glucagon-peptide like 1", "incretin hormone", "GLP-1 receptor agonist", and "prostate cancer". Secondary search involved reference lists of eligible articles. The key criterion was to identify studies that included GLP-1 receptor, incretin hormones, GLP-1 receptor agonists, and their role in prostate cancer development.

RESULTS

77 publications were selected for inclusion in this review. The studies contained in publications allowed us to summarize the data on the role of GLP-1 receptor and it's agonists in prostate cancer biology and development. The following review aims to discuss and provide information about the role of incretin hormones in prostate cancer pathogenesis and its clinical implication in patients with prostate cancer.

CONCLUSION

Incretin hormone-dependent pathways play an important role in prostate cancer pathogenesis. Moreover, GLP-1 receptor agonists seems to be a promising therapeutical agents when it comes to finding new therapies in patients with more aggressive and/or advanced stages of prostate cancer.

Sex Differences in Maturation and Function of Neonatal Porcine Islets Upon Transplantation in Mice

BACKGROUND

Neonatal porcine islets (NPIs) can mature into a mixed population of endocrine cells that can restore glucose control in mice, pigs, and non-human primates, representing a potential alternative islet source for clinical beta cell replacement therapy. However, it remains unclear how conditions in the recipient influence the maturation and function of these cells. Here, we investigated the impact of host sex on NPIs implanted under the kidney capsule of male and female B6.129S7-Rag1tm1Mom (B6/Rag-/-) mice.

METHODS

Diabetic mice were transplanted with 3000 NPIs under the kidney capsule. All mice were monitored for reversal of hyperglycemia and glucose clearance at 8- and 20-weeks post-transplant. Grafts were assessed for cell composition and insulin content.

RESULTS

Female mice demonstrated improved glucose clearance at 8- and 20-weeks post-transplant compared to their male counterparts. Improved glucose clearance correlated with accelerated diabetes reversal in females (8 weeks vs. 12 weeks in males) and increased rates of euglycemic achievement (17/18 in females vs. 14/19 in males). However, grafts collected from male mice exhibited an increased percentage of insulin-positive cells as well as increased insulin content.

CONCLUSION

The sex of the host influences the outcomes of NPI transplantation, showcasing the relevance of understanding the role of sex as a biological variable in islet transplantation.

Impact of Sexual Dimorphism on Therapy Response in Patients with Metabolic Dysfunction-Associated Steatotic Liver Disease: From Conventional and Nutritional Approaches to Emerging Therapies

Metabolic dysfunction-associated steatotic liver disease (MASLD) represents a spectrum of liver disease ranging from hepatic fat accumulation to steatohepatitis (metabolic dysfunction-associated steatohepatitis, MASH), fibrosis, cirrhosis, and potentially hepatocellular carcinoma in the absence of excessive alcohol consumption. MASLD is characterized by substantial inter-individual variability in terms of severity and rate of progression, with a prevalence that is generally higher in men than in women. Steroids metabolism is characterized by sexual dimorphism and may have an impact on liver disease progression; indeed, several therapeutic strategies targeting hormone receptors are under phase 2/3 development. Despite the fact that the importance of sexual dimorphism in the setting of MASLD is well recognized, the underlying molecular mechanisms that can potentially drive the disease toward progression are not clear. The aim of this review is to delve into the crosstalk between sexual dimorphism and steroid hormone perturbation under nutritional and pharmacological intervention.

GLP-1 and Its Analogs: Does Sex Matter?

While obesity and diabetes are prevalent in both men and women, some aspects of these diseases differ by sex. A new blockbuster class of therapeutics, glucagon-like peptide 1 (GLP-1) analogs (eg, semaglutide), shows promise at curbing both diseases. This review addresses the topic of sex differences in the endogenous and therapeutic actions of GLP-1 and its analogs. Work on sex differences in human studies and animal research is reviewed. Preclinical data on the mechanisms of potential sex differences in the endogenous GLP-1 system as well as the therapeutic effect of GLP-1 analogs, focusing on the effects of the drugs on the brain and behavior relating to appetite and metabolism, are highlighted. Moreover, recent clinical evidence of sex differences in the therapeutic effects of GLP-1 analogs in obesity, diabetes, and cardiovascular disease are discussed. Lastly, we review evidence for the role of GLP-1 analogs in mood and reproductive function, with particular attention to sex differences. Overall, while we did not find evidence for many qualitative sex differences in the therapeutic effect of clinically approved GLP-1 analogs, a growing body of literature highlights quantitative sex differences in the response to GLP-1 and its analogs as well as an interaction of these therapeutics with estrogens. What also clearly emerges is the paucity of data in female animal models or women in very basic aspects of the science of GLP-1-gaps that should be urgently mended, given the growing popularity of these medications, especially in women.

Sulfation pathways in the maintenance of functional beta-cell mass and implications for diabetes

Diabetes Type 1 and Type 2 are widely occurring diseases. In spite of a vast amount of biomedical literature about diabetic processes in general, links to certain biological processes are only becoming evident these days. One such area of biology is the sulfation of small molecules, such as steroid hormones or metabolites from the gastrointestinal tract, as well as larger biomolecules, such as proteins and proteoglycans. Thus, modulating the physicochemical propensities of the different sulfate acceptors, resulting in enhanced solubility, expedited circulatory transit, or enhanced macromolecular interaction. This review lists evidence for the involvement of sulfation pathways in the maintenance of functional pancreatic beta-cell mass and the implications for diabetes, grouped into various classes of sulfated biomolecule. Complex heparan sulfates might play a role in the development and maintenance of beta-cells. The sulfolipids sulfatide and sulfo-cholesterol might contribute to beta-cell health. In beta-cells, there are only very few proteins with confirmed sulfation on some tyrosine residues, with the IRS4 molecule being one of them. Sulfated steroid hormones, such as estradiol-sulfate and vitamin-D-sulfate, may facilitate downstream steroid signaling in beta-cells, following de-sulfation. Indoxyl sulfate is a metabolite from the intestine, that causes kidney damage, contributing to diabetic kidney disease. Finally, from a technological perspective, there is heparan sulfate, heparin, and chondroitin sulfate, that all might be involved in next-generation beta-cell transplantation. Sulfation pathways may play a role in pancreatic beta-cells through multiple mechanisms. A more coherent understanding of sulfation pathways in diabetes will facilitate discussion and guide future research.

Sex-specific regulatory architecture of pancreatic islets from subjects with and without type 2 diabetes

Patients with type 2 and type 1 diabetes (T2D and T1D) exhibit sex-specific differences in insulin secretion, the mechanisms of which are unknown. We examined sex differences in human pancreatic islets from 52 donors with and without T2D combining single cell RNA-sequencing (scRNA-seq) and single nucleus ATAC-sequencing (snATAC-seq) with assays probing hormone secretion and bioenergetics. In non-diabetic (ND) donors, sex differences in islet cell chromatin accessibility and gene expression predominantly involved sex chromosomes. In contrast, islets from T2D donors exhibited similar sex differences in sex chromosome-encoded differentially expressed genes (DEGs) as ND donors, but also exhibited sex differences in autosomal genes. Comparing β cells from T2D and ND donors, gene enrichment of female β cells showed suppression in mitochondrial respiration, while male β cells exhibited suppressed insulin secretion, suggesting a role for mitochondrial failure in females in the transition to T2D. We finally performed cell type-specific, sex stratified, GWAS restricted to differentially accessible chromatin peaks across T2D, fasting glucose, and fasting insulin traits. We identified that differentially accessible regions overlap with T2D-associated variants in a sex- and cell type-specific manner.

Mechanisms in endocrinology: hypogonadism and metabolic health in men-novel insights into pathophysiology

Hypogonadism in men is associated with an adverse metabolic phenotype and increased mortality. Reciprocally, obesity and insulin resistance can suppress the hypothalamic-pituitary-gonadal axis in the absence of structural organic disease, further perpetuating a cycle of metabolic dysfunction and low testosterone. The mechanisms underpinning this bidirectional association are complex as hypogonadism is a heterogenous syndrome, and obesity is associated with metabolic perturbations in glucose and lipid metabolism even in the presence of normal testicular function. However, distinct molecular defects specific to testosterone deficiency have been identified in pathways relating to glucose and lipid metabolism in target metabolic depots such as adipose tissue and skeletal muscle. This review discusses the etiology and prevalence of metabolic disease in male hypogonadism, with a specific focus on both disease mechanisms and novel potential approaches to enhance our understanding.

Opposing impact of hypertension/diabetes following hormone therapy initiation and preexisting statins on castration resistant progression of nonmetastatic prostate cancer: a multicenter study

Hormone therapy, especially androgen deprivation therapy (ADT), is effective against prostate cancer (PC), whereas long-term ADT is a risk for metabolic/cardiovascular disorders including diabetes (DM), hypertension (HT) and dyslipidemia (DL), and might result in progression to castration-resistant prostate cancer (CRPC). We thus conducted a multicenter retrospective cohort study to ask whether CRPC progression would be associated positively with HT, DM or DL and negatively with statins prescribed for treatment of DL. In this study, 1,112 nonmetastatic PC patients undergoing ADT were enrolled. Univariate statistical analyses clearly showed significant association of HT or DM developing after ADT onset, though not preexisting HT or DM, with early CRPC progression. On the other hand, preexisting DL or statin use, but not newly developed DL or started statin prescriptions following ADT, was negatively associated with CRPC progression. Multivariate analysis revealed significant independent association of the newly developed DM or HT, or preexisting statin use with CRPC progression [adjusted hazard ratios (95% confidence intervals): 3.85 (1.65-8.98), p = 0.002; 2.75 (1.36-5.59), p = 0.005; 0.25 (0.09-0.72), p = 0.010, respectively]. Together, ADT-related development of HT or DM and preexisting statin use are considered to have positive and negative impact on CRPC progression, respectively.

Extra-nuclear and cytoplasmic steroid receptor signalling in hormone dependent cancers

Steroid hormone receptors are key mediators in the execution of hormone action through a combination of genomic and non-genomic action. Since their isolation and characterisation in the early 20th Century much of our understanding of the biological actions of steroid hormones are underpinned by their activated receptor activity. Over the past two decades there has been an acceleration of more omics-based research which has resulted in a major uptick in our comprehension of genomic steroid action. However, it is well understood that steroid hormones can induce very rapid signalling events in tandem with their genomic actions wherein they exert their influence through alterations in gene expression. Thus the totality of genomic and non-genomic steroid action occurs in a simultaneous and reciprocal manner and a greater appreciation of whole cell action is required to fully evaluate steroid hormone activity in vivo. In this mini-review we outline the most recent developments in non-genomic steroid action and cytoplasmic steroid hormone receptor biology in endocrine-related cancers with a focus on the 3-keto steroid receptors, in particular the androgen receptor.

Metabolic benefits afforded by estradiol and testosterone in both sexes: clinical considerations

Testosterone (T) and 17β-estradiol (E2) are produced in male and female humans and are potent metabolic regulators in both sexes. When E2 and T production stops or decreases during aging, metabolic dysfunction develops and promotes degenerative metabolic and vascular disease. Here, we discuss the shared benefits afforded by E2 and T for metabolic function human females and males. In females, E2 is central to bone and vascular health, subcutaneous adipose tissue distribution, skeletal muscle insulin sensitivity, antiinflammatory immune function, and mitochondrial health. However, T also plays a role in female skeletal, vascular, and metabolic health. In males, T's conversion to E2 is fundamental to bone and vascular health, as well as prevention of excess visceral adiposity and the promotion of insulin sensitivity via activation of the estrogen receptors. However, T and its metabolite dihydrotestosterone also prevent excess visceral adiposity and promote skeletal muscle growth and insulin sensitivity via activation of the androgen receptor. In conclusion, T and E2 are produced in both sexes at sex-specific concentrations and provide similar and potent metabolic benefits. Optimizing levels of both hormones may be beneficial to protect patients from cardiometabolic disease and frailty during aging, which requires further study.

Testosterone in prevention and treatment of type 2 diabetes in men: Focus on recent randomized controlled trials

In epidemiological studies, lowered serum testosterone concentrations are common in men with obesity, prediabetes, and established type 2 diabetes (T2D). In men with prediabetes, lowered serum testosterone also predicts a future risk of T2D in men. Administration of testosterone consistently reduces fat mass and increases skeletal muscle mass-body compositional changes expected to be metabolically favorable. In men with established T2D, the effects of testosterone treatment on glycemic measures are inconsistent. Irrespective of baseline serum testosterone concentration in men with prediabetes or newly diagnosed early-onset T2D, testosterone treatment prescribed in conjunction with a lifestyle program has been reported to reduce the risk of T2D by 40% after 2 years, suggesting that either a lifestyle program is required to facilitate the glycemic benefit of testosterone treatment and/or that testosterone treatment has more favorable effects on glycemia in men early in the evolution or onset of the disease. The durability of the benefit and longer-term safety of testosterone treatment have not been established. Therefore, more studies are required before testosterone treatment can be recommended for the prevention and/or treatment of men with or at elevated risk of T2D who do not have hypogonadism due to an established disease of the hypothalamic-pituitary-testicular axis.

Beyond reproduction: unraveling the impact of sex hormones on cardiometabolic health

This review thoroughly explores the multifaceted roles of sexual hormones, emphasizing their impact beyond reproductive functions and underscoring their significant influence on cardiometabolic regulation. It analyzes the broader physiological implications of estrogen, testosterone, and progesterone, highlighting their effects on metabolic syndrome, lipid metabolism, glucose homeostasis, and cardiovascular health. Drawing from diverse molecular, clinical, and therapeutic studies, the paper delves into the intricate interplay between these hormones and cardiometabolic processes. By presenting a comprehensive analysis that goes beyond traditional perspectives, and recognizing sexual hormones as more than reproductive agents, the review sheds light on their broader significance in health and disease management, advocating for holistic and personalized medical approaches.

Single cell regulatory architecture of human pancreatic islets suggests sex differences in β cell function and the pathogenesis of type 2 diabetes

Type 2 and type 1 diabetes (T2D, T1D) exhibit sex differences in insulin secretion, the mechanisms of which are unknown. We examined sex differences in human pancreatic islets from 52 donors with and without T2D combining single cell RNA-seq (scRNA-seq), single nucleus assay for transposase-accessible chromatin sequencing (snATAC-seq), hormone secretion, and bioenergetics. In nondiabetic (ND) donors, sex differences in islet cells gene accessibility and expression predominantly involved sex chromosomes. Islets from T2D donors exhibited similar sex differences in sex chromosomes differentially expressed genes (DEGs), but also exhibited sex differences in autosomal genes. Comparing β cells from T2D vs. ND donors, gene enrichment of female β cells showed suppression in mitochondrial respiration, while male β cells exhibited suppressed insulin secretion. Thus, although sex differences in gene accessibility and expression of ND β cells predominantly affect sex chromosomes, the transition to T2D reveals sex differences in autosomes highlighting mitochondrial failure in females.

Prevalence of new-onset diabetes mellitus after kidney transplantation: a systematic review and meta-analysis

AIMS

Post-transplant diabetes is a prevalent and consequential complication following kidney transplantation, which significantly augments the risk of cardiovascular disease, graft loss, infection, and mortality, thereby profoundly impacting both graft and patient survival. However, the early stages of post-transplant diabetes often go unnoticed or receive inadequate management. Consequently, this study systematically assesses the incidence of new-onset diabetes after kidney transplantation with the aim to enhance medical staff awareness regarding post-transplantation diabetes and provide clinical management guidance.

METHODS

We conducted a comprehensive search across multiple databases including PubMed, Web of Science, Embase, The Cochrane Library, CNKI, Wanfang, VIP, and SinoMed until September 21, 2023. Data extraction was performed using standardized tables and meta-analysis was conducted using Stata 16.0 software. A random effects model was employed to estimate the combined prevalence along with its corresponding 95% confidence interval. The source of heterogeneity was explored using subgroup analysis and sensitivity analysis, while publication bias was assessed through funnel plot and Egger's test. This study has been registered with PROSPERO under the registration number CRD42023465768.

RESULTS

This meta-analysis comprised 39 studies with a total sample size of 16,584 patients. The prevalence of new-onset diabetes after transplantation was found to be 20% [95% CI (18.0, 22.0)]. Subgroup analyses were conducted based on age, gender, body mass index, family history of diabetes, type of kidney donor, immunosuppressive regimen, acute rejection episodes, hepatitis C infection status and cytomegalovirus infection.

CONCLUSIONS

The incidence of post-kidney transplantation diabetes is substantial, necessitating early implementation of preventive and control measures to mitigate its occurrence, enhance prognosis, and optimize patients' quality of life.

CLINICAL TRIAL REGISTRATION

PROSPERO: CRD42023465768.

Single cell regulatory architecture of human pancreatic islets suggests sex differences in β cell function and the pathogenesis of type 2 diabetes

Biological sex affects the pathogenesis of type 2 and type 1 diabetes (T2D, T1D) including the development of β cell failure observed more often in males. The mechanisms that drive sex differences in β cell failure is unknown. Studying sex differences in islet regulation and function represent a unique avenue to understand the sex-specific heterogeneity in β cell failure in diabetes. Here, we examined sex and race differences in human pancreatic islets from up to 52 donors with and without T2D (including 37 donors from the Human Pancreas Analysis Program [HPAP] dataset) using an orthogonal series of experiments including single cell RNA-seq (scRNA-seq), single nucleus assay for transposase-accessible chromatin sequencing (snATAC-seq), dynamic hormone secretion, and bioenergetics. In cultured islets from nondiabetic (ND) donors, in the absence of the in vivo hormonal environment, sex differences in islet cell type gene accessibility and expression predominantly involved sex chromosomes. Of particular interest were sex differences in the X-linked KDM6A and Y-linked KDM5D chromatin remodelers in female and male islet cells respectively. Islets from T2D donors exhibited similar sex differences in differentially expressed genes (DEGs) from sex chromosomes. However, in contrast to islets from ND donors, islets from T2D donors exhibited major sex differences in DEGs from autosomes. Comparing β cells from T2D and ND donors revealed that females had more DEGs from autosomes compared to male β cells. Gene set enrichment analysis of female β cell DEGs showed a suppression of oxidative phosphorylation and electron transport chain pathways, while male β cell had suppressed insulin secretion pathways. Thus, although sex-specific differences in gene accessibility and expression of cultured ND human islets predominantly affect sex chromosome genes, major differences in autosomal gene expression between sexes appear during the transition to T2D and which highlight mitochondrial failure in female β cells.

Polychlorinated biphenyls exposure and type 2 diabetes: Molecular mechanism that causes insulin resistance and islet damage

Polychlorinated biphenyls (PCBs) are typical persistent organic pollutants that have been associated with type 2 diabetes (T2DM) in cohort studies. This review aims to comprehensively assess the molecular mechanisms of PCBs-induced T2DM. Recent progress has been made in the research of PCBs in liver tissue, adipose tissue, and other tissues. By influencing the function of nuclear receptors, such as the aryl hydrocarbon receptor (AhR), pregnancy X receptor (PXR), and peroxisome proliferator activated receptor γ (PPARγ), as well as the inflammatory response, PCBs disrupt the balance of hepatic glucose and lipid metabolism. This is associated with insulin resistance (IR) in the target organ of insulin. Through androgen receptor (AR), estrogen receptor α/β (ERα/β), and pancreato-duodenal-homeobox gene-1 (PDX-1), PCBs affect the secretion of insulin and increase blood glucose. Thus, this review is a discussion on the relationship between PCBs exposure and the pathogenesis of T2DM. It is hoped to provide basic concepts for diabetes research and disease treatment.

Androgen-induced upregulation of CFTR in pancreatic β-cell contributes to hyperinsulinemia in PCOS model

PURPOSE

Polycystic ovarian syndrome (PCOS) is an endocrine-metabolic condition affecting 5-10% of reproductive-aged women and characterized by hyperandrogenism, insulin resistance (IR), and hyperinsulinemia. CFTR is known to be regulated by steroid hormones, and our previous study has demonstrated an essential role of CFTR in β-cell function. This study aims to investigate the contribution of androgen and CFTR to hypersecretion of insulin in PCOS and the underlying mechanism.

METHODS

We established a rat PCOS model by subcutaneously implanting silicon tubing containing Dihydrotestosterone (DHT). Glucose tolerance test with insulin levels was performed at 9 weeks after implantation. A rat β-cell line RINm5F, a mouse β-cell line β-TC-6, and mouse islets were treated with DHT, and with or without the androgen antagonist flutamide for CFTR and insulin secretion-related functional assays or mRNA/protein expression measurement. The effect of CFTR inhibitors on DHT-promoted membrane depolarization, glucose-stimulated intracellular Ca2+ oscillation and insulin secretion were examined by membrane potential imaging, calcium imaging and ELISA, respectively.

RESULTS

The DHT-induced PCOS model showed increased body weight, impaired glucose tolerance, and higher blood glucose and insulin levels after glucose stimulation. CFTR was upregulated in islets of PCOS model and DHT-treated cells, which was reversed by flutamide. The androgen receptor (AR) could bind to the CFTR promoter region, which was enhanced by DHT. Furthermore, DHT-induced membrane depolarization, enhanced glucose-stimulated Ca2+ oscillations and insulin secretion, which could be abolished by CFTR inhibitors.

CONCLUSIONS

Excessive androgen enhances glucose-stimulating insulin secretion through upregulation of CFTR, which may contribute to hyperinsulinemia in PCOS.

Filamin A cooperates with the androgen receptor in preventing skeletal muscle senescence

Aging induces a slow and progressive decrease in muscle mass and function, causing sarcopenia. Androgens control muscle trophism and exert important anabolic functions through the binding to the androgen receptor. Therefore, analysis of the androgen receptor-mediated actions in skeletal muscle might provide new hints for a better understanding of sarcopenia pathogenesis. In this study, we report that expression of the androgen receptor in skeletal muscle biopsies from 20 subjects is higher in young, as compared with old subjects. Co-immunoprecipitation experiments reveal that the androgen receptor is complexed with filamin A mainly in young, that in old subjects. Therefore, we have in depth analyzed the role of such complex using C2C12 myoblasts that express a significant amount of the androgen receptor. In these cells, hormone stimulation rapidly triggers the assembly of the androgen receptor/filamin A complex. Such complex prevents the senescence induced by oxidative stress in C2C12 cells, as disruption of the androgen receptor/filamin A complex by Rh-2025u stapled peptide re-establishes the senescent phenotype in C2C12 cells. Simultaneously, androgen stimulation of C2C12 cells rapidly triggers the activation of various signaling effectors, including Rac1, focal adhesion kinase, and mitogen-activated kinases. Androgen receptor blockade by bicalutamide or perturbation of androgen receptor/filamin A complex by Rh-2025u stapled peptide both reverse the hormone activation of signaling effectors. These findings further reinforce the role of the androgen receptor and its extranuclear partners in the rapid hormone signaling that controls the functions of C2C12 cells. Further investigations are needed to promote clinical interventions that might ameliorate muscle cell function as well the clinical outcome of age-related frailty.

Advances in mitochondria-centered mechanism behind the roles of androgens and androgen receptor in the regulation of glucose and lipid metabolism

An increasing number of studies have reported that androgens and androgen receptors (AR) play important roles in the regulation of glucose and lipid metabolism. Impaired glucose and lipid metabolism and the development of obesity-related diseases have been found in either hypogonadal men or male rodents with androgen deficiency. Exogenous androgens supplementation can effectively improve these disorders, but the mechanism by which androgens regulate glucose and lipid metabolism has not been fully elucidated. Mitochondria, as powerhouses within cells, are key organelles influencing glucose and lipid metabolism. Evidence from both pre-clinical and clinical studies has reported that the regulation of glucose and lipid metabolism by androgens/AR is strongly associated with the impact on the content and function of mitochondria, but few studies have systematically reported the regulatory effect and the molecular mechanism. In this paper, we review the effect of androgens/AR on mitochondrial content, morphology, quality control system, and function, with emphases on molecular mechanisms. Additionally, we discuss the sex-dimorphic effect of androgens on mitochondria. This paper provides a theoretical basis for shedding light on the influence and mechanism of androgens on glucose and lipid metabolism and highlights the mitochondria-based explanation for the sex-dimorphic effect of androgens on glucose and lipid metabolism.

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.

Neuronal AR Regulates Glucose Homeostasis and Energy Expenditure in Lean Female Mice With Androgen Excess

Hyperandrogenemia and polycystic ovary syndrome are a result of the imbalance of androgen levels in females. Androgen receptor (Ar) mediates the effect of androgen, and this study examines how neuronal Ar in the central nervous system mediates metabolism under normal and increased androgen conditions in female mice. The neuron-specific ARKO mouse (SynARKO) was created from female (Ar fl/wt; synapsin promoter driven Cre) and male (Ar fl/y) mice. A glucose tolerance test revealed impaired glucose tolerance that was partially alleviated in the SynARKO-dihydrotestosterone (DHT) mice compared with Con-DHT mice after 4 months of DHT treatment. Heat production and food intake was higher in Con-DHT mice than in Con-veh mice; these effects were not altered between SynARKO-veh and SynARKO-DHT mice, indicating that excess androgens may partially alter calorie intake and energy expenditure in females via the neuronal Ar. The pAkt/Akt activity was higher in the hypothalamus in Con-DHT mice than in Con-veh mice, and this effect was attenuated in SynARKO-DHT mice. Western blot studies show that markers of inflammation and microglia activation, such as NF-kB p-65 and IBA1, increased in the hypothalamus of Con-DHT mice compared with Con-veh. These studies suggest that neuronal Ar mediates the metabolic impacts of androgen excess in females.

Architecture of androgen receptor pathways amplifying glucagon-like peptide-1 insulinotropic action in male pancreatic β cells

Male mice lacking the androgen receptor (AR) in pancreatic β cells exhibit blunted glucose-stimulated insulin secretion (GSIS), leading to hyperglycemia. Testosterone activates an extranuclear AR in β cells to amplify glucagon-like peptide-1 (GLP-1) insulinotropic action. Here, we examined the architecture of AR targets that regulate GLP-1 insulinotropic action in male β cells. Testosterone cooperates with GLP-1 to enhance cAMP production at the plasma membrane and endosomes via: (1) increased mitochondrial production of CO2, activating the HCO3--sensitive soluble adenylate cyclase; and (2) increased Gαs recruitment to GLP-1 receptor and AR complexes, activating transmembrane adenylate cyclase. Additionally, testosterone enhances GSIS in human islets via a focal adhesion kinase/SRC/phosphatidylinositol 3-kinase/mammalian target of rapamycin complex 2 actin remodeling cascade. We describe the testosterone-stimulated AR interactome, transcriptome, proteome, and metabolome that contribute to these effects. This study identifies AR genomic and non-genomic actions that enhance GLP-1-stimulated insulin exocytosis in male β cells.

Sex differences in glycolipidic disorders after exposure to maternal hyperglycemia during early development

PURPOSE

The aim of this review was to summarize sex differences in glycolipid metabolic phenotypes of human and animal models after exposure to maternal hyperglycemia and overview the underlying mechanisms, providing a new perspective on the maternal hyperglycemia-triggered risk of glycolipidic disorders in offspring.

METHODS

A comprehensive literature search within PubMed was performed. Selected publications related to studies on offspring exposed to maternal hyperglycemia investigating the sex differences of glycolipid metabolism were reviewed.

RESULTS

Maternal hyperglycemia increases the risk of glycolipid metabolic disorders in offspring, such as obesity, glucose intolerance and diabetes. Whether with or without intervention, metabolic phenotypes have been shown to exhibit sex differences between male and female offspring in response to maternal hyperglycemia, which may be related to gonadal hormones, organic intrinsic differences, placenta, and epigenetic modifications.

CONCLUSION

Sex may play a role in the different incidences and pathogenesis of abnormal glycolipid metabolism. More studies investigating both sexes are needed to understand how and why environmental conditions in early life affect long-term health between male and female individuals.

Interaction between gut microbiota and sex hormones and their relation to sexual dimorphism in metabolic diseases

Metabolic diseases, such as obesity, metabolic syndrome (MetS) and type 2 diabetes (T2D), are now a widespread pandemic in the developed world. These pathologies show sex differences in their development and prevalence, and sex steroids, mainly estrogen and testosterone, are thought to play a prominent role in this sexual dimorphism. The influence of sex hormones on these pathologies is not only reflected in differences between men and women, but also between women themselves, depending on the hormonal changes associated with the menopause. The observed sex differences in gut microbiota composition have led to multiple studies highlighting the interaction between steroid hormones and the gut microbiota and its influence on metabolic diseases, ultimately pointing to a new therapy for these diseases based on the manipulation of the gut microbiota. This review aims to shed light on the role of sexual hormones in sex differences in the development and prevalence of metabolic diseases, focusing on obesity, MetS and T2D. We focus also the interaction between sex hormones and the gut microbiota, and in particular the role of microbiota in aspects such as gut barrier integrity, inflammatory status, and the gut-brain axis, given the relevance of these factors in the development of metabolic diseases.

Genetically predicted testosterone and cancers risk in men: a two-sample Mendelian randomization study

OBJECTIVE

In observational studies, testosterone has been reported to be associated with some types of cancers. However, the direction and magnitude of the causal association between testosterone and different types of cancer remain unclear. This Mendelian randomization study assessed the causal associations of total testosterone (TT) and bioavailable testosterone (BT) with cancer risk in men.

METHODS

We performed two-sample Mendelian randomization using publicly available GWAS summary statistics to investigate the genetically causal association between testosterone and the risk of 22 kinds of cancers in men. Causal estimates were calculated by the inverse variance weighted method. We also performed additional sensitivity tests to evaluate the validity of the casualty.

RESULTS

Genetically predicted BT level were significantly associated with an increased risk of prostate cancer [odds ratio (OR) = 1.17 95% confidence interval (CI): 1.09-1.26, P = 2.51E-05] in the MR analysis with the IVW method. TT was found to be the suggestive protective factor against stomach cancer (OR = 0.66, 95% CI: 0.48-0.93, P = 0.0116) as well as pancreatic cancer (OR = 0.59, 95% CI: 0.36-0.96, P = 0.0346). A suggestive association was found between TT and the occurrence of small intestine cancer (OR = 1.0004, 95% CI: 1.0001-1.0007, P = 0.0116). However, testosterone had no significant association with other cancers.

CONCLUSION

This study investigated the role of testosterone in the development of prostate cancer, stomach cancer, pancreatic cancer, and small intestine cancer but found no strong association with the other cancers in men.

β Cell mass expansion during puberty involves serotonin signaling and determines glucose homeostasis in adulthood

Puberty is associated with transient insulin resistance that normally recedes at the end of puberty; however, in overweight children, insulin resistance persists, leading to an increased risk of type 2 diabetes. The mechanisms whereby pancreatic β cells adapt to pubertal insulin resistance, and how they are affected by the metabolic status, have not been investigated. Here, we show that puberty is associated with a transient increase in β cell proliferation in rats and humans of both sexes. In rats, β cell proliferation correlated with a rise in growth hormone (GH) levels. Serum from pubertal rats and humans promoted β cell proliferation, suggesting the implication of a circulating factor. In pubertal rat islets, expression of genes of the GH/serotonin (5-hydroxytryptamine [5-HT]) pathway underwent changes consistent with a proliferative effect. Inhibition of the pro-proliferative 5-HT receptor isoform HTR2B blocked the increase in β cell proliferation in pubertal islets ex vivo and in vivo. Peripubertal metabolic stress blunted β cell proliferation during puberty and led to altered glucose homeostasis later in life. This study identifies a role of GH/GH receptor/5-HT/HTR2B signaling in the control of β cell mass expansion during puberty and identifies a mechanistic link between pubertal obesity and the risk of developing type 2 diabetes.

Zmiz1 is required for mature β-cell function and mass expansion upon high fat feeding

OBJECTIVE

Identifying the transcripts which mediate genetic association signals for type 2 diabetes (T2D) is critical to understand disease mechanisms. Studies in pancreatic islets support the transcription factor ZMIZ1 as a transcript underlying a T2D GWAS signal, but how it influences T2D risk is unknown.

METHODS

β-Cell-specific Zmiz1 knockout (Zmiz1^βKO) mice were generated and phenotypically characterised. Glucose homeostasis was assessed in Zmiz1^βKO mice and their control littermates on chow diet (CD) and high fat diet (HFD). Islet morphology and function were examined by immunohistochemistry and in vitro islet function was assessed by dynamic insulin secretion assay. Transcript and protein expression were assessed by RNA sequencing and Western blotting. In islets isolated from genotyped human donors, we assessed glucose-dependent insulin secretion and islet insulin content by static incubation assay.

RESULTS

Male and female Zmiz1^βKO mice were glucose intolerant with impaired insulin secretion, compared with control littermates. Transcriptomic profiling of Zmiz1^βKO islets identified over 500 differentially expressed genes including those involved in β-cell function and maturity, which we confirmed at the protein level. Upon HFD, Zmiz1^βKO mice fail to expand β-cell mass and become severely diabetic. Human islets from carriers of the ZMIZ1-linked T2D-risk alleles have reduced islet insulin content and glucose-stimulated insulin secretion.

CONCLUSIONS

β-Cell Zmiz1 is required for normal glucose homeostasis. Genetic variation at the ZMIZ1 locus may influence T2D-risk by reducing islet mass expansion upon metabolic stress and the ability to maintain a mature β-cell state.

The Roles of Androgens in Humans: Biology, Metabolic Regulation and Health

Androgens are an important and diverse group of steroid hormone molecular species. They play varied functional roles, such as the control of metabolic energy fate and partition, the maintenance of skeletal and body protein and integrity and the development of brain capabilities and behavioral setup (including those factors defining maleness). In addition, androgens are the precursors of estrogens, with which they share an extensive control of the reproductive mechanisms (in both sexes). In this review, the types of androgens, their functions and signaling are tabulated and described, including some less-known functions. The close interrelationship between corticosteroids and androgens is also analyzed, centered in the adrenal cortex, together with the main feedback control systems of the hypothalamic-hypophysis-gonads axis, and its modulation by the metabolic environment, sex, age and health. Testosterone (T) is singled out because of its high synthesis rate and turnover, but also because age-related hypogonadism is a key signal for the biologically planned early obsolescence of men, and the delayed onset of a faster rate of functional losses in women after menopause. The close collaboration of T with estradiol (E2) active in the maintenance of body metabolic systems is also presented Their parallel insufficiency has been directly related to the ravages of senescence and the metabolic syndrome constellation of disorders. The clinical use of T to correct hypoandrogenism helps maintain the functionality of core metabolism, limiting excess fat deposition, sarcopenia and cognoscitive frailty (part of these effects are due to the E2 generated from T). The effectiveness of using lipophilic T esters for T replacement treatments is analyzed in depth, and the main problems derived from their application are discussed.

Association of androgen receptor expression with glucose metabolic features in triple-negative breast cancer

Background

Androgen receptor (AR) is a potential therapeutic target in triple-negative breast cancer (TNBC). We aimed to elucidate the association of AR expression with glucose metabolic features in TNBC.

Methods

Two independent datasets were analyzed: FDG PET data of our institution and a public dataset of GSE135565. In PET analysis, patients with TNBC who underwent pretreatment PET between Jan 2013 and Dec 2017 were retrospectively enrolled. Clinicopathologic features and maximum standardized uptake value (SUVmax) of tumors were compared with AR expression. In GSE135565 dataset, glycolysis score was calculated by the pattern of glycolysis-related genes, and of which association with SUVmax and AR gene expression were analyzed.

Results

A total of 608 female patients were included in the PET data of our institution. SUVmax was lower in AR-positive tumors (P < 0.001) and correlated with lower AR expression (rho = –0.26, P < 0.001). In multivariate analysis, AR was a deterministic factor for low SUVmax (P = 0.012), along with other key clinicopathologic features. In the GSE135565 dataset, AR expression also exhibited a negative correlation with SUVmax (r = –0.34, P = 0.001) and the glycolysis score (r = –0.27, P = 0.013).

Conclusions

Low glucose metabolism is a signature of AR expression in TNBC. It is suggested that evaluation of AR expression status needs to be considered in clinical practice particularly in TNBC with low glucose metabolism.

High-fidelity reprogramming into Leydig-like cells by CRISPR activation and paracrine factors

Androgen deficiency is a common medical conditions that affects males of all ages. Transplantation of testosterone-producing cells is a promising treatment for male hypogonadism. However, getting a cell source with the characteristics of Leydig cells (LCs) is still a challenge. Here, a high-efficiency reprogramming of skin-derived fibroblasts into functional Leydig-like cells (LLCs) based on epigenetic mechanism was described. By performing an integrated analysis of genome-wide DNA methylation and transcriptome profiling in LCs and fibroblasts, the potentially epigenetic-regulating steroidogenic genes and signaling pathways were identified. Then by using CRISPR/dCas9 activation system and signaling pathway regulators, the male- or female-derived fibroblasts were reprogrammed into LLCs with main LC-specific traits. Transcriptomic analysis further indicated that the correlation coefficients of global genes and transcription factors between LLCs and LCs were higher than 0.81 and 0.96, respectively. After transplantation in the testes of hypogonadal rodent models, LLCs increased serum testosterone concentration significantly. In type 2 diabetic rats model, LLCs which were transplanted in armpit, have the capability to restore the serum testosterone level and improve the hyperglycemia status. In conclusion, our approach enables skin-derived fibroblasts reprogramming into LLCs with high fidelity, providing a potential cell source for the therapeutics of male hypogonadism and metabolic-related comorbidities.

Effects of androgens on glucose metabolism

Type 2 diabetes (T2D) and obesity are common and associated with increased morbidity and mortality. Cross-sectional and longitudinal studies have demonstrated a clear association between T2D, obesity and reduced total testosterone concentration. This relationship becomes less significant or absent with correction for changes in body composition, supporting the notion that changes in body composition are mediating these effects. Moreover, this mediating effect of body composition changes is bi-directional, as evidenced by interventional studies of weight loss and testosterone treatment. On the one hand, in obese men, serum testosterone increases markedly with weight loss. On the other hand, testosterone improves body composition. This relationship is driven by multiple complex interaction between obesity and insulin resistance and the hypothalamic-pituitary-testicular axis, at all levels. Data from randomised control trials have demonstrated that intervention with testosterone therapy increases muscle mass and reduces adiposity. Most recently it has been shown that treatment with testosterone prevents progression of impaired glucose tolerance to T2D, or reverses newly diagnosed T2D beyond lifestyle intervention alone. At present there are insufficient safety data to support the use of testosterone for prevention of type 2 diabetes.

Membrane-Initiated Estrogen, Androgen, and Progesterone Receptor Signaling in Health and Disease

Rapid effects of steroid hormones were discovered in the early 1950s, but the subject was dominated in the 1970s by discoveries of estradiol and progesterone stimulating protein synthesis. This led to the paradigm that steroid hormones regulate growth, differentiation, and metabolism via binding a receptor in the nucleus. It took 30 years to appreciate not only that some cellular functions arise solely from membrane-localized steroid receptor (SR) actions, but that rapid sex steroid signaling from membrane-localized SRs is a prerequisite for the phosphorylation, nuclear import, and potentiation of the transcriptional activity of nuclear SR counterparts. Here, we provide a review and update on the current state of knowledge of membrane-initiated estrogen (ER), androgen (AR) and progesterone (PR) receptor signaling, the mechanisms of membrane-associated SR potentiation of their nuclear SR homologues, and the importance of this membrane-nuclear SR collaboration in physiology and disease. We also highlight potential clinical implications of pathway-selective modulation of membrane-associated SR.

Prenatal exposure to a mixture of PAHs causes the dysfunction of islet cells in adult male mice: Association with type 1 diabetes mellitus

Polycyclic aromatic hydrocarbons (PAHs) have been detected throughout the human body. Whether exposure to PAHs is associated with the incidence of type 1 diabetes mellitus should be investigated. To this end, pregnant mice were exposed to mixed PAHs (5, 50, or 500 μg/kg) once every other day during gestation. The adult male offspring displayed impaired glucose tolerance and reduced serum levels of glucagon and insulin. Immunohistochemical staining revealed increased numbers of apoptotic β-cells and a reduced β-cell mass in these males. The downregulated expression of pancreatic estrogen receptor α, androgen receptor, and transcription factor PDX1 was responsible for impacting β-cell development. The relatively reduced α-cell area was associated with downregulated ARX expression. The transcription of Isn2 and Gcg in pancreatic tissue was downregulated, which indicated that the function of β-cells and α-cells was impaired. Methylation levels in the Isn2 promotor were significantly elevated in mice prenatally exposed to 500 µg/kg PAHs, which was consistent with the change in its mRNA levels. The number of macrophages infiltrating islets was significantly increased, indicating that prenatal PAH exposure might reduce islet cell numbers in an autoimmune manner. This study shows that prenatal exposure to PAHs may promote the pathogenesis of type 1 diabetes mellitus.

Physiological and pharmacological actions of glucagon like peptide-1 (GLP-1) in domestic animals

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GLP-1 improves peripheral glucose uptake in healthy dogs and cats.

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GLP-1 analogues administration in diabetic cats reduces exogenous insulin requirement.

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Dogs cardiomyocytes apoptosis is reduced by GLP-1-derived molecules action.

Analogues of glucagon like peptide-1 (GLP-1) and other drugs that increase this peptide half-life are used worldwide in human medicine to treat type 2 diabetes mellitus (DM) and obesity. These molecules can increase insulin release and satiety, interesting effects that could also be useful in the treatment of domestic animals pathologies, however their use in veterinary medicine are still limited. Considering the increasing incidence of DM and obesity in cats and dogs, the aim of this review is to summarize the available information about the physiological and pharmacological actions of GLP-1 in domestic animals and discuss about its potential applications in veterinary medicine. In diabetic dogs, the use of drugs based on GLP-1 actions reduced blood glucose and increased glucose uptake, while in diabetic cats they reduced glycemic variability and exogenous insulin administration. Thus, available evidence indicates that GLP-1 based drugs could become alternatives to DM treatment in domestic animals. Nevertheless, current data do not provide enough elements to recommend these drugs widespread clinical use.

Adapting Physiology in Functional Human Islet Organogenesis

Generation of three-dimensional (3D)-structured functional human islets is expected to be an alternative cell source for cadaveric human islet transplantation for the treatment of insulin-dependent diabetes. Human pluripotent stem cells (hPSCs), such as human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), offer infinite resources for newly synthesized human islets. Recent advancements in hPSCs technology have enabled direct differentiation to human islet-like clusters, which can sense glucose and secrete insulin, and those islet clusters can ameliorate diabetes when transplanted into rodents or non-human primates (NHPs). However, the generated hPSC-derived human islet-like clusters are functionally immature compared with primary human islets. There remains a challenge to establish a technology to create fully functional human islets in vitro, which are functionally and transcriptionally indistinguishable from cadaveric human islets. Understanding the complex differentiation and maturation pathway is necessary to generate fully functional human islets for a tremendous supply of high-quality human islets with less batch-to-batch difference for millions of patients. In this review, I summarized the current progress in the generation of 3D-structured human islets from pluripotent stem cells and discussed the importance of adapting physiology for in vitro functional human islet organogenesis and possible improvements with environmental cues.

Testosterone Deficiency Promotes Hypercholesteremia and Attenuates Cholesterol Liver Uptake via AR/PCSK9/LDLR Pathways

BACKGROUND

Testosterone deficiency is reportedly correlated with an elevation of cholesterol in plasma, but the mechanism remains unclear. Our objective was to investigate the effects of testosterone deficiency on cholesterol metabolism and the corresponding molecular changes in vivo and in vitro.

METHODS

SD rats were randomized into three groups: sham-operated (SHAM), subtotal orchiectomized (SO), and orchiectomized (ORX) and fed for 8 weeks. HepG2 cells were cultured with medium containing testosterone with the final concentrations of 0, 10, 30, and 300 nM. Method of isotope tracing and fluorescence labelling was adopted to investigate cholesterol metabolism. Several key molecules of cholesterol metabolism were also analyzed.

RESULTS

SO and ORX rats displayed dysfunctional liver uptake of cholesterol. HepG2 cells incubated with testosterone of lower and excessive level exhibited reduced capacity of cholesterol uptake. Further investigation revealed that lack of testosterone induced increased proprotein convertase subtilisin/kexin type 9 (PCSK9) and decreased low-density lipoprotein receptor (LDLR) both in vivo and in vitro. Moreover, the androgen receptor (AR) antagonist flutamide mimicked the effects of testosterone deficiency on PCSK9 and LDLR indicating the role of AR as a mediator in triggering attenuating liver cholesterol uptake in which testosterone instead of dihydrotestosterone (DHT) is the major functional form of androgen.

CONCLUSION

Testosterone deficiency attenuated cholesterol liver uptake mediated by the PCSK9-LDLR pathway, in which AR and testosterone without transforming to DHT play important roles.

Maternal antagonism of Glp1 reverses the adverse outcomes of sleeve gastrectomy on mouse offspring

Mothers that underwent bariatric surgery are at higher risk for delivering a small-for-gestational age (SGA) infant. This phenomenon is attributed to malabsorption and rapid weight loss following surgery. We compared pregnancy outcomes in lean mice that underwent sham surgery or sleeve gastrectomy (SG). SG led to a reduction in glucose levels and an increase in postprandial levels of glucagon-like peptide 1 (Glp1) without affecting mice weight during pregnancy. Pups of SG-operated mice (SG pups) were born SGA. The placenta and pancreas of the pups were not affected by SG, although a high-fat diet caused hepatic steatosis and glucose intolerance in male SG pups. Treatment with a Glp1 receptor antagonist during pregnancy normalized the birth weight of SG pups and diminished the adverse response to a high-fat diet without affecting glucose levels of pregnant mice. The antagonist did not affect the birth weight of pups of sham-operated mice. Our findings link elevated Glp1 signaling, rather than weight loss, to the increased prevalence of SGA births following bariatric surgery with metabolic consequences for the offspring. The long-term effects of bariatric surgery on the metabolic health of offspring of patients require further investigation.

Gender differences in new hypoglycemic drug effects on renal outcomes: a systematic review

INTRODUCTION

Lifetime diabetes risk is greater in women than in men. Women with diabetes mellitus (DM) have a greater prevalence of diabetic kidney disease (DKD) risk factors. The diagnosis of DM is often delayed in women, with poorer outcomes and with expected therapeutic goals missed.

AREA COVERED

A systematic literature review following PRISMA guidelines was conducted in the PubMed gateway of the MEDLINE database and Clinicaltrials.gov. The purpose of our research was to establish the sex differences on renal outcomes in users of the new hypoglycemic drugs: sodium-glucose transport protein 2 inhibitors (SGLT-2i), dipeptidyl peptidase-IV Inhibitors (DPP-IVi) and glucagon-like peptide-1 inhibitors (GLP-1i).

EXPERT OPINION

New hypoglycemic drugs represent promising tools in the treatment and prevention of severe complications of diabetes, cardiovascular diseases and chronic kidney disease. Even if renal outcomes are investigated in both randomized controlled trials and cardiovascular outcome trials, gender-based analysis is not always performed. Our systematic review demonstrated that the gap among sexes in DKD can be partially filled using new hypoglycemic drugs. Sexual dimorphism analysis could represent a keystone for the development of adequate gender-specific therapies.

Comparative analysis of oral and intraperitoneal glucose tolerance tests in mice

Objective

The glucose tolerance test (GTT) is widely used in preclinical research to investigate glucose metabolism, but there is no standardised way to administer glucose. The aim of this study was to directly compare the effect of the route of glucose administration on glucose and insulin kinetics during a GTT in mice.

Methods

A GTT was performed in lean male and female mice and obese male mice and glucose was administered via the oral or intraperitoneal (I.P.) route. Samples were collected frequently during the GTT to provide a full time-course of the insulin and glucose excursions. In another cohort of lean male mice, plasma concentrations of insulin, c-peptide, and incretin hormones were measured at early time points after glucose administration. A stable-isotope labelled GTT (SiGTT) was then performed to delineate the contribution of exogenous and endogenous glucose to glycemia during the GTT, comparing both methods of glucose administration. Finally, we present a method to easily measure insulin from small volumes of blood during a GTT by directly assaying whole-blood insulin using ELISA and show a good concordance between whole-blood and plasma insulin measurements.

Results

We report that I.P. glucose administration results in an elevated blood glucose excursion and a largely absent elevation in blood insulin and plasma incretin hormones when compared to oral administration. Utilising stable-isotope labelled glucose, we demonstrate that the difference in glucose excursion between the two routes of administration is mainly due to the lack of suppression of glucose production in I.P. injected mice. Additionally, rates of exogenous glucose appearance into circulation were different between lean and obese mice after I.P., but not after oral glucose administration.

Conclusion

Reflecting on these data, we suggest that careful consideration be given to the route of glucose administration when planning a GTT procedure in mice and that in most circumstances the oral route of glucose administration should be preferred over the I.P. route to avoid possible artifacts originating from a non-physiological route.

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Intraperitoneal glucose administration does not promote insulin secretion.

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Exogenous glucose appearance is delayed in obese mice after intraperitoneal administration.

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Hepatic glucose production is suppressed after administering oral not intraperitoneal glucose.

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Measuring insulin from whole blood is comparable to that from plasma.

Intestinal Gpr17 deficiency improves glucose metabolism by promoting GLP-1 secretion

G protein-coupled receptors (GPCRs) in intestinal enteroendocrine cells (EECs) respond to nutritional, neural, and microbial cues and modulate the release of gut hormones. Here we show that Gpr17, an orphan GPCR, is co-expressed in glucagon-like peptide-1 (GLP-1)-expressing EECs in human and rodent intestinal epithelium. Acute genetic ablation of Gpr17 in intestinal epithelium improves glucose tolerance and glucose-stimulated insulin secretion (GSIS). Importantly, inducible knockout (iKO) mice and Gpr17 null intestinal organoids respond to glucose or lipid ingestion with increased secretion of GLP-1, but not the other incretin glucose-dependent insulinotropic polypeptide (GIP). In an in vitro EEC model, overexpression or agonism of Gpr17 reduces voltage-gated calcium currents and decreases cyclic AMP (cAMP) production, and these are two critical factors regulating GLP-1 secretion. Together, our work shows that intestinal Gpr17 signaling functions as an inhibitory pathway for GLP-1 secretion in EECs, suggesting intestinal GPR17 is a potential target for diabetes and obesity intervention.

Yan et al. locate GPR17 expression in the enteroendocrine cells of human and rodent intestinal epithelium. They find that GPR17 signaling inhibits intracellular rise of cAMP and calcium and that loss of intestinal Gpr17 in rodents leads to better glucose tolerance via increased hormone secretion in response to nutrient ingestion.

Androgens and Development of Posttransplantation Diabetes Mellitus in Male Kidney Transplant Recipients: A Post Hoc Analysis of a Prospective Study

OBJECTIVE

Posttransplantation diabetes mellitus (PTDM) effects up to 30% of all kidney transplant recipients (KTR). Recent studies in mice found that sufficient androgen levels are necessary for β-cell health and adequate insulin secretion. This raises the question whether a similar relationship might be present in KTR. Hence, we hypothesized that dihydrotestosterone and testosterone are associated with the development of PTDM in male KTR.

RESEARCH DESIGN AND METHODS

We conducted a post hoc analyses of a prospective single-center cohort study including adult male KTR with a functioning graft ≥1 year posttransplantation. Androgen levels were assessed by liquid chromatography-tandem mass spectrometry. Development of PTDM was defined according to the American Diabetes Association's criteria.

RESULTS

We included 243 male KTR (aged 51 ± 14 years), with a median dihydrotestosterone 0.9 (0.7-1.3) nmol/L and testosterone of 12.1 (9.4-15.8) nmol/L. During 5.3 (3.7-5.8) years of follow-up, 28 KTR (11.5%) developed PTDM. A clear association was observed, as 15 (19%), 10 (12%), and 3 (4%) male KTR developed PTDM in the respective tertiles of dihydrotestosterone (P = 0.008). In Cox regression analyses, both dihydrotestosterone and testosterone as continuous variables were inversely associated with the risk to development PTDM, independent of glucose and HbA_1c (hazard ratio [HR] 0.31 [95% CI 0.16-0.59], P < 0.001; and HR 0.32 [95% CI 0.15-0.68], P = 0.003, respectively).

CONCLUSIONS

Our results suggest that low androgen levels are a novel potential modifiable risk factor for the development of PTDM in male KTR.

Sex hormones regulate metainflammation in diet-induced obesity in mice

Men have a statistically higher risk of metabolic and cardiovascular disease than premenopausal women, but the mechanisms mediating these differences are elusive. Chronic inflammation during obesity contributes to disease risk and is significantly more robust in males. Prior work demonstrated that compared with obese males, obese females have reduced proinflammatory adipose tissue macrophages (ATMs). Given the paucity of data on how sex hormones contribute to macrophage responses in obesity, we sought to understand the role of sex hormones in promoting obesity-induced myeloid inflammation. We used gonadectomy, estrogen receptor-deficient alpha chimeras, and androgen-insensitive mice to model sex hormone deficiency. These models were evaluated in diet-induced obesity conditions (high-fat diet [HFD]) and in vitro myeloid assays. We found that ovariectomy increased weight gain and adiposity. Ovariectomized females had increased ATMs and bone marrow myeloid colonies compared with sham-gonadectomized females. In addition, castrated males exposed to HFD had improved glucose tolerance, insulin sensitivity, and adiposity with fewer Ly6chi monocytes and bone marrow myeloid colonies compared with sham-gonadectomized males, although local adipose inflammation was enhanced. Similar findings were observed in androgen-insensitive mice; however, these mice had fewer CD11c+ ATMs, implying a developmental role for androgens in myelopoiesis and adipose inflammation. We concluded that gonadectomy results in convergence of metabolic and inflammatory responses to HFD between the sexes, and that myeloid estrogen receptor alpha contributes minimally to diet-induced inflammatory responses, whereas loss of androgen-receptor signaling improves metabolic and inflammatory outcomes. These studies demonstrate that sex hormones play a critical role in sex differences in obesity, metabolic dysfunction, and myeloid inflammation.

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.

Non-glucose modulators of insulin secretion in healthy humans: (dis)similarities between islet and in vivo studies

Optimal metabolic homeostasis requires precise temporal and quantitative control of insulin secretion. Both in vivo and in vitro studies have often focused on the regulation by glucose although many additional factors including other nutrients, neurotransmitters, hormones and drugs, modulate the secretory function of pancreatic β-cells. This review is based on the analysis of clinical investigations characterizing the effects of non-glucose modulators of insulin secretion in healthy subjects, and of experimental studies testing the same modulators in islets isolated from normal human donors. The aim was to determine whether the information gathered in vitro can reliably be translated to the in vivo situation. The comparison evidenced both convincing similarities and areas of discordance. The lack of coherence generally stems from the use of exceedingly high concentrations of test agents at too high or too low glucose concentrations in vitro, which casts doubts on the physiological relevance of a number of observations made in isolated islets. Future projects resorting to human islets should avoid extreme experimental conditions, such as oversized stimulations or inhibitions of β-cells, which are unlikely to throw light on normal insulin secretion and contribute to the elucidation of its defects.

Development of diabetes mellitus following hormone therapy in prostate cancer patients is associated with early progression to castration resistance

To identify risk factors for the prognosis of prostate cancer (PC), we retrospectively analyzed the impact of lifestyle-related disorders as well as PC characteristics at initial diagnosis on the progression to castration-resistant PC (CRPC) in PC patients undergoing hormone therapy. Of 648 PC patients, 230 who underwent hormone therapy and met inclusion criteria were enrolled in this study. CRPC developed in 48 patients (20.9%). Univariate analysis using Cox proportional hazard model indicated that newly developed diabetes mellitus (DM) following hormone therapy (postDM), but not preexisting DM, as well as PC characteristics at initial diagnosis including prostate-specific antigen (PSA) ≥ 18 were significantly associated with the progression to CRPC. A similar tendency was also observed in the relationship between newly developed hypertension following hormone therapy and CRPC progression. On the other hand, neither dyslipidemia nor hyperuricemia, regardless the onset timing, exhibited any association with CRPC progression. In multivariate analysis, postDM and PSA ≥ 18 were extracted as independent risk factors for CRPC progression (adjusted hazard ratios, 3.38 and 2.34; p values, 0.016 and 0.019, respectively). Kaplan–Meier analysis and log-rank test clearly indicated earlier progression to CRPC in PC patients who developed postDM or had relatively advanced initial PC characteristics including PSA ≥ 18. Together, the development of lifestyle-related disorders, particularly DM, following hormone therapy, as well as advanced PC characteristics at initial diagnosis is considered to predict earlier progression to CRPC and poor prognosis in PC patients undergoing hormone therapy.

Testosterone Therapy Effects on Bone Mass and Turnover in Hypogonadal Men with Type 2 Diabetes

CONTEXT

Male hypogonadism is associated with low bone mineral density (BMD) and increased fragility fracture risk. Patients with type 2 diabetes (T2D) have relatively higher BMD, but greater fracture risk.

OBJECTIVE

Evaluate the skeletal response to testosterone therapy in hypogonadal men with T2D compared with hypogonadal men without T2D.

METHODS

Single arm, open-label clinical trial (NCT01378299) involving 105 men (40-74 years old), with average morning testosterone <300 ng/dL. Subjects were injected intramuscularly with testosterone cypionate (200 mg) every 2 weeks for 18 months. Testosterone and estradiol were assessed by liquid chromatography/mass spectrometry; serum C-terminal telopeptide of type I collagen (CTX), osteocalcin and sclerostin by enzyme-linked immunosorbent assay; glycated hemoglobin (HbA1c) by high-performance liquid chromatography, areal BMD (aBMD) and body composition by dual-energy x-ray absorptiometry; tibial volumetric BMD (vBMD) and bone geometry by peripheral quantitative computed tomography.

RESULTS

Among our population of hypogonadal men, 49 had T2D and 56 were non-T2D. After 18 months of testosterone therapy, there were no differences in circulating testosterone and estradiol between the groups. Hypogonadal men with T2D had increased osteocalcin, reflecting increased osteoblast activity, compared with non-T2D men (P < .01). T2D men increased lumbar spine aBMD (P < .05), total area at 38% tibia (P < .01) and periosteal and endosteal circumferences at the same site (P < .01 for both). T2D men had reduced tibial vBMD (P < .01), but preserved bone mineral content (P = .01). Changes in HbA1c or body composition were similar between the 2 groups.

CONCLUSION

Testosterone therapy results in greater improvements in the skeletal health of hypogonadal men with T2D than their nondiabetic counterparts.

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.

Loss of growth hormone signaling in the mouse germline or in adulthood reduces islet mass and alters islet function with notable sex differences

In the endocrine pancreas, growth hormone (GH) is known to promote pancreatic islet growth and insulin secretion. In this study, we show that GH receptor (GHR) loss in the germline and in adulthood impacts islet mass in general but more profoundly in male mice. GHR knockout (GHRKO) mice have enhanced insulin sensitivity and low circulating insulin. We show that the total cross-sectional area of isolated islets (estimated islet mass) was reduced by 72% in male but by only 29% in female GHRKO mice compared with wild-type controls. Also, islets from GHRKO mice secreted ∼50% less glucose-stimulated insulin compared with size-matched islets from wild-type mice. We next used mice with a floxed Ghr gene to knock down the GHR in adult mice at 6 mo of age (6mGHRKO) and examined the impact on glucose and islet metabolism. By 12 mo of age, female 6mGHRKO mice had increased body fat and reduced islet mass but had no change in glucose tolerance or insulin sensitivity. However, male 6mGHRKO mice had nearly twice as much body fat, substantially reduced islet mass, and enhanced insulin sensitivity, but no change in glucose tolerance. Despite large losses in islet mass, glucose-stimulated insulin secretion from isolated islets was not significantly different between male 6mGHRKO and controls, whereas isolated islets from female 6mGHRKO mice showed increased glucose-stimulated insulin release. Our findings demonstrate the importance of GH to islet mass throughout life and that unique sex-specific adaptations to the loss of GH signaling allow mice to maintain normal glucose metabolism.NEW & NOTEWORTHY Growth hormone (GH) is important for more than just growth. GH helps to maintain pancreatic islet mass and insulin secretion throughout life. Sex-specific adaptations to the loss of GH signaling allow mice to maintain normal glucose regulation despite losing islet mass.

Single-cell RNA Sequencing Reveals Sexually Dimorphic Transcriptome and Type 2 Diabetes Genes in Mouse Islet β Cells

Type 2 diabetes (T2D) is characterized by the malfunction of pancreatic β cells. Susceptibility and pathogenesis of T2D can be affected by multiple factors, including sex differences. However, the mechanisms underlying sex differences in T2D susceptibility and pathogenesis remain unclear. Using single-cell RNA sequencing (scRNA-seq), we demonstrate the presence of sexually dimorphic transcriptomes in mouse β cells. Using a high-fat diet-induced T2D mouse model, we identified sex-dependent T2D altered genes, suggesting sex-based differences in the pathological mechanisms of T2D. Furthermore, based on islet transplantation experiments, we found that compared to mice with sex-matched islet transplants, sex-mismatched islet transplants in healthy mice showed down-regulation of genes involved in the longevity regulating pathway of β cells. Moreover, the diabetic mice with sex-mismatched islet transplants showed impaired glucose tolerance. These data suggest sexual dimorphism in T2D pathogenicity, indicating that sex should be considered when treating T2D. We hope that our findings could provide new insights for the development of precision medicine in T2D.