Glucose Dyshomeostasis Research Articles

Associations between environmental glyphosate exposure and glucose homeostasis indices in US general adults: a national population-based cross-sectional study

As glyphosate’s application becomes increasingly widespread across the globe, its potential adverse effects on humans have garnered growing concerns. Little evidence has revealed the associations between glyphosate and glucose homeostasis. A total of 2094 individuals were recruited from the NHANES 2013–2018. Urinary glyphosate, alkaline phosphatase (ALP), fasting plasma glucose (FPG), fasting insulin, and glycated hemoglobin A1c (HbA1c) were measured. Homeostatic model assessment of beta-cell function (HOMA2-β), insulin resistance (HOMA2-IR), and insulin sensitivity (HOMA2-IS) were assessed. Generalized linear models and mediation analyses were fitted to estimate the potential associations between glyphosate, glucose homeostasis, and ALP. Urinary glyphosate demonstrated a statistically significant positive association with FPG and HbA1c in a linear positive dose–response manner, while showing a linear negative association with HOMA2-β. Each doubling increase in urinary glyphosate was associated with a 1.13%, 1.50%, and − 2.80% alteration in FPG, HbA1c, and HOMA2-β, respectively. Obesity modified the association between urinary glyphosate and glucose dyshomeostasis with stronger associations in obese individuals. In addition, elevated ALP significantly mediated the associations of urinary glyphosate with FPG and HbA1c, with mediated proportions of 9.91% and 20.23%, respectively. Environmental glyphosate exposure was associated with glucose dyshomeostasis, which was more pronounced in obese individuals and was partly mediated by ALP.

Acute inhibition of iron-sulfur cluster biosynthesis disrupts metabolic flexibility in mice.

Acute ISC inhibition leads to rapid loss of adiposity in miceMulti-metabolic pathway disruption upon ISC deficiency blocks energy storageNfs1 inhibition induces glucose dyshomeostasis due to ISC deficiency in β-cellsEnergy distress caused by inhibition of ISC synthesis is attenuated in aged mice.

Associations between Glyphosate Exposure and Glycemic Disorders: A Focus on the Modifying Effect of Sex Hormones.

Widespread glyphosate contamination in the environment and its endocrine-disrupting potential are concerning. However, evidence of glyphosate's effects on glycemic health is limited. To examine the association between glyphosate and glucose homeostasis in the general US population, a total of 3038 individuals were enrolled from the 2013-2016 cycles of the National Health and Nutrition Examination Survey (NHANES). Survey-weighted linear regression and restricted cubic spline curves were used to detect the associations between glyphosate and glycemic disorders. The effects of interactions between sex hormones and glyphosate on glycemic outcomes were evaluated. The results showed that glyphosate was significantly linked to increased glycated hemoglobin A1c (HbA1c) levels (β = 0.01; 95%CI, 0.01 to 0.02; p = 0.001) and the compromised homeostatic model assessment of beta-cell function (HOMA-beta) scores (β = -0.09; 95%CI, -0.17 to -0.01; p = 0.024). More importantly, these "glyphosate-glycemic disorder" associations were significantly modified by sex hormone-binding globulin (SHBG; P for interaction < 0.05), with more pronounced relationships being identified in individuals with low SHBG levels. Our findings indicate that glyphosate is correlated with glucose dyshomeostasis. Individuals with low SHBG levels exhibited susceptibility to glyphosate-related glycemic toxicity; therefore, it might be prudent to determine glycemic health in those subjects with glyphosate exposure.

The MODY-associated KCNK16 L114P mutation increases islet glucagon secretion and limits insulin secretion resulting in transient neonatal diabetes and glucose dyshomeostasis in adults.

The gain-of-function mutation in the TALK-1 K+ channel (p.L114P) is associated with maturity-onset diabetes of the young (MODY). TALK-1 is a key regulator of β-cell electrical activity and glucose-stimulated insulin secretion. The KCNK16 gene encoding TALK-1 is the most abundant and β-cell-restricted K+ channel transcript. To investigate the impact of KCNK16 L114P on glucose homeostasis and confirm its association with MODY, a mouse model containing the Kcnk16 L114P mutation was generated. Heterozygous and homozygous Kcnk16 L114P mice exhibit increased neonatal lethality in the C57BL/6J and the CD-1 (ICR) genetic background, respectively. Lethality is likely a result of severe hyperglycemia observed in the homozygous Kcnk16 L114P neonates due to lack of glucose-stimulated insulin secretion and can be reduced with insulin treatment. Kcnk16 L114P increased whole-cell β-cell K+ currents resulting in blunted glucose-stimulated Ca2+ entry and loss of glucose-induced Ca2+ oscillations. Thus, adult Kcnk16 L114P mice have reduced glucose-stimulated insulin secretion and plasma insulin levels, which significantly impairs glucose homeostasis. Taken together, this study shows that the MODY-associated Kcnk16 L114P mutation disrupts glucose homeostasis in adult mice resembling a MODY phenotype and causes neonatal lethality by inhibiting islet insulin secretion during development. These data suggest that TALK-1 is an islet-restricted target for the treatment for diabetes.

The MODY-associated KCNK16 L114P mutation increases islet glucagon secretion and limits insulin secretion resulting in transient neonatal diabetes and glucose dyshomeostasis in adults

The gain-of-function mutation in the TALK-1 K+ channel (p.L114P) is associated with maturity-onset diabetes of the young (MODY). TALK-1 is a key regulator of β-cell electrical activity and glucose-stimulated insulin secretion. The KCNK16 gene encoding TALK-1 is the most abundant and β-cell-restricted K+ channel transcript. To investigate the impact of KCNK16 L114P on glucose homeostasis and confirm its association with MODY, a mouse model containing the Kcnk16 L114P mutation was generated. Heterozygous and homozygous Kcnk16 L114P mice exhibit increased neonatal lethality in the C57BL/6J and the CD-1 (ICR) genetic background, respectively. Lethality is likely a result of severe hyperglycemia observed in the homozygous Kcnk16 L114P neonates due to lack of glucose-stimulated insulin secretion and can be reduced with insulin treatment. Kcnk16 L114P increased whole-cell β-cell K+ currents resulting in blunted glucose-stimulated Ca2+ entry and loss of glucose-induced Ca2+ oscillations. Thus, adult Kcnk16 L114P mice have reduced glucose-stimulated insulin secretion and plasma insulin levels, which significantly impairs glucose homeostasis. Taken together, this study shows that the MODY-associated Kcnk16 L114P mutation disrupts glucose homeostasis in adult mice resembling a MODY phenotype and causes neonatal lethality by inhibiting islet insulin secretion during development. These data suggest that TALK-1 is an islet-restricted target for the treatment for diabetes.

Imbalance in Glucose Metabolism Regulates the Transition of Microglia from Homeostasis to Disease-Associated Microglia Stage 1.

Microglia undergo two-stage activation in neurodegenerative diseases, known as disease-associated microglia (DAM). TREM2 mediates the DAM2 stage transition, but what regulates the first DAM1 stage transition is unknown. We report that glucose dyshomeostasis inhibits DAM1 activation and PKM2 plays a role. As in tumors, PKM2 was aberrantly elevated in both male and female human AD brains, but unlike in tumors, it is expressed as active tetramers, as well as among TREM2+ microglia surrounding plaques in 5XFAD male and female mice. snRNAseq analyses of microglia without Pkm2 in 5XFAD mice revealed significant increases in DAM1 markers in a distinct metabolic cluster, which is enriched in genes for glucose metabolism, DAM1, and AD risk. 5XFAD mice incidentally exhibited a significant reduction in amyloid pathology without microglial Pkm2 Surprisingly, microglia in 5XFAD without Pkm2 exhibited increases in glycolysis and spare respiratory capacity, which correlated with restoration of mitochondrial cristae alterations. In addition, in situ spatial metabolomics of plaque-bearing microglia revealed an increase in respiratory activity. These results together suggest that it is not only glycolytic but also respiratory inputs that are critical to the development of DAM signatures in 5XFAD mice.

Daily fluctuations in blood glucose with normal aging are inversely related to hippocampal synaptic mitochondrial proteins

Defective brain glucose utilization is a hallmark of Alzheimer’s disease (AD) while Type II diabetes and elevated blood glucose escalate the risk for AD in later life. Isolating contributions of normal aging from coincident metabolic or brain diseases could lead to refined approaches to manage specific health risks and optimize treatments targeted to susceptible older individuals. We evaluated metabolic, neuroendocrine, and neurobiological differences between young adult (6 months) and aged (24 months) male rats. Compared to young adults, blood glucose was significantly greater in aged rats at the start of the dark phase of the day but not during the light phase. When challenged with physical restraint, a potent stressor, aged rats effected no change in blood glucose whereas blood glucose increased in young adults. Tissues were evaluated for markers of oxidative phosphorylation (OXPHOS), neuronal glucose transport, and synapses. Outright differences in protein levels between age groups were not evident, but circadian blood glucose was inversely related to OXPHOS proteins in hippocampal synaptosomes, independent of age. The neuronal glucose transporter, GLUT3, was positively associated with circadian blood glucose in young adults whereas aged rats tended to show the opposite trend. Our data demonstrate aging increases daily fluctuations in blood glucose and, at the level of individual differences, negatively associates with proteins related to synaptic OXPHOS. Our findings imply that glucose dyshomeostasis may exacerbate metabolic aspects of synaptic dysfunction that contribute to risk for age-related brain disorders.

Puberty as a DOHaD programming window: high-fat diet induces long-term hepatic dysfunction in male rats.

The aim of this study was to evaluate whether high-fat (HF) diet intake during puberty can program obesity as well as generate glucose imbalance and hepatic metabolic dysfunctions in adult life. Male Wistar rats were randomly assigned into two groups: rats fed standard chow (NF) and rats fed a HF from postnatal 30-day-old (PND30) until PND60. Then, both groups were fed a standard chow from PND60 until PND120. Euthanasia and samples collections occurred at PND120. HF animals were overweight (+11%) and had increased adiposity, hyperphagia (+12%), hyperglycaemia (+13%), hyperinsulinemia (+69%), and hypertriglyceridemia (+34%). Plasma glucose levels during intravenous glucose tolerance test (ivGTT) and intraperitoneal insulin tolerance test (ipITT) were also higher in the HF group, whereas Kitt was significantly lower (-34%), suggesting reduced insulin sensitivity. In the same sense, HF animals present pancreatic islets hypertrophy and high β-cell mass. HF animals also had a significant increase in blood glucose levels during pyruvate tolerance test, indicating increased gluconeogenesis. Hepatic morphology analyses showed an increase in lipid inclusion in the HF group. Moreover, PEPCK and FAS protein expression were higher in the livers of the HF animals (+79% and + 37%, respectively). In conclusion, HF during puberty causes obese phenotype leading to glucose dyshomeostasis and nonalcoholic fatty liver disease, which can be related to the overexpression of proteins PEPCK and FAS.

Astrocytic FoxO1 in the hypothalamus regulates metabolic homeostasis by coordinating neuropeptide Y neuron activity.

The forkhead box transcription factor O1 (FoxO1) is expressed ubiquitously throughout the central nervous system, including in astrocytes, the most prevalent glial cell type in the brain. While the role of FoxO1 in hypothalamic neurons in controlling food intake and energy balance is well-established, the contribution of astrocytic FoxO1 in regulating energy homeostasis has not yet been determined. In the current study, we demonstrate the essential role of hypothalamic astrocytic FoxO1 in maintaining normal neuronal activity in the hypothalamus and whole-body glucose metabolism. Inhibition of FoxO1 function in hypothalamic astrocytes shifts the cellular metabolism from glycolysis to oxidative phosphorylation, enhancing astrocyte ATP production and release meanwhile decreasing astrocytic export of lactate. As a result, specific deletion of astrocytic FoxO1, particularly in the hypothalamus, causes a hyperactivation of hypothalamic neuropeptide Y neurons, which leads to an increase in acute feeding and impaired glucose regulation and ultimately results in diet-induced obesity and systemic glucose dyshomeostasis.

85-OR: Swi/Snf Controls Transcriptional Programs Required for ß-Cell Development and Postnatal Islet Function

A key feature of diabetes is insufficient functional β-cell mass. Strategies to augment functional β-cell mass include directed differentiation of stem cells towards a β-cell fate, which requires extensive knowledge of transcriptional programs governing differentiation in vivo. Pdx1, an essential transcription factor involved in β-cell differentiation, dynamically recruits coregulators to drive different gene expression programs. A recent study identified the ATP-dependent Swi/Snf chromatin remodeling complex as an important Pdx1-interacting partner. In the developing pancreas, conditional removal of the Brg Swi/Snf ATPase subunit compromised final pancreas mass, and loss of both ATPase subunits, Brg1 and Brm, led to glucose dyshomeostasis. While Swi/Snf is essential during early pancreas development and mature β-cell function, the role of Swi/Snf during endocrine cell development has yet to be explored. Here, we generated a conditional knockout of either Brg1 (Brg1ΔendoBrm+/-), Brm (Brg1Δendo/+Brm-/-), or both subunits (DKOΔendo) during endocrine development using Neurogenin 3 Cre. Four-week-old Brg1ΔendoBrm+/- mice are glucose intolerant, hyperglycemic, and hypoinsulinemic, with no phenotype observed in Brg1Δendo/+Brm-/-mice. Impaired glucose homeostasis of Brg1ΔendoBrm+/- mice was due in part to reduced islet number, impaired insulin secretion, and altered gene expression programs. DKOΔendo mice have not been found at weaning; however, postnatal day 6 DKOΔendo mice are severely hyperglycemic with reduced plasma insulin levels. Single-cell RNA-Seq of embryonic day 15.5 lineage-labeled cells revealed reduced insulin and glucagon transcript in the β-cell and α-cell clusters, respectively, in both Brg1ΔendoBrm+/- and DKOΔendo mice and reduced Neurogenin 3­ transcript in DKOΔendo endocrine progenitor clusters. These data suggest Swi/Snf plays a critical role in governing gene-expression programs essential for endocrine cell development. Disclosure R.K.Davidson: Employee; Eli Lilly and Company. S.Kanojia: None. M.E.Osmulski: None. J.Spaeth: None. Funding National Institutes of Health (R01DK129287, R03DK127129)

Acrolein Exposure Impaired Glucose Homeostasis and Increased Risk of Type 2 Diabetes: An Urban Adult Population-Based Cohort Study with Repeated Measures

Acrolein is an identified high-priority hazardous air pollutant ubiquitous in daily life and associated with cardiometabolic risk that attracts worldwide attention. However, the etiology role of acrolein exposure in glucose dyshomeostasis and type 2 diabetes (T2D) is unclear. This repeated-measurement prospective cohort study included 3522 urban adults. Urine/blood samples were repeatedly collected for determinations of acrolein metabolites (N-acetyl-S-(3-hydroxypropyl)-l-cysteine, N-acetyl-S-(2-carboxyethyl)-l-cysteine; acrolein exposure biomarkers), glucose homeostasis, and T2D at baseline and a three-year follow-up. We found that each 3-fold increment in acrolein metabolites was cross-sectionally associated with 5.91-6.52% decrement in homeostasis model assessment-insulin sensitivity (HOMA-IS) and 0.07-0.14 mmol/L, 4.02-4.57, 5.91-6.52, 19-20, 18-19, and 23-31% increments in fasting glucose (FPG), fasting insulin (FPI), HOMA-insulin resistance (HOMA-IR), risks of prevalent IR, impaired fasting glucose (IFG), and T2D, respectively; longitudinally, participants with sustained-high acrolein metabolite levels had increased risks of incident IR, IFG, and T2D by 63-80, 87-99, and 120-154%, respectively (P < 0.05). In addition, biomarkers of heme oxygenase-1 activity (exhaled carbon monoxide), lipid peroxidation (8-iso-prostaglandin-F2α), protein carbonylation (protein carbonyls), and oxidative DNA damage (8-hydroxy-deoxyguanosine) mediated 5.00-38.96% of these associations. Our study revealed that acrolein exposure may impair glucose homeostasis and increase T2D risk via mediating mechanisms of heme oxygenase-1 activation, lipid peroxidation, protein carbonylation, and oxidative DNA damage.

Obesity modifies the association of environmental pyrethroid exposure with glucose homeostasis in the US general adults

Environmental pyrethroids are concerning due to their widespread residues and potential implications on human health. We aimed to assess the association of pyrethroid exposure with glucose homeostasis and examine the interaction between obesity and pyrethroid exposure. A total of 4233 US general adults from the National Health and Nutrition Examination Survey with measured urinary pyrethroid metabolites, fasting plasma glucose (FPG), fasting insulin (FINS), and glycated hemoglobin A1c (HbA1c) were included in the study. The homeostasis model assessment (HOMA2) calculator was utilized to assess insulin resistance (HOMA2-IR), insulin sensitivity (HOMA2-IS), and beta-cell function (HOMA2-β). We estimated the associations of pyrethroid metabolites with glucose homeostasis parameters (FPG, FINS, HbA1c, HOMA2-IR, HOMA2-IS, and HOMA2-β) using multivariate linear regression models and restricted cubic spline models and further assessed the interaction between obesity and pyrethroid metabolites on glucose dyshomeostasis. Urinary 3-phenoxybenzoic acid (3-PBA) was the most detected pyrethroid metabolite (81%) with a median concentration of 0.43 (interquartile range 0.20–1.01) μg/g urinary creatinine. Compared with the participants in the lowest quartile, those in the highest quartile of 3-PBA had a 1.93% (95% confidence interval: 0.46%, 3.42%), 6.69% (1.96%, 11.64%), 1.60% (0.64%, 2.57%), 7.06% (2.33%, 12.01%), −6.59% (−10.72%, −2.28%), and 1.10% (−2.69%, 5.04%) alteration in FPG, FINS, HbA1c, HOMA2-IR, HOMA2-IS, and HOMA2-β, respectively. The restricted cubic spline model displayed a linear positive association between 3-PBA and FPG, FINS, HbA1c, and HOMA2-IR, and a negative association with HOMA2-IS (all P for overall <0.05 and P for non-linear >0.05). Additionally, the association between urinary 3-PBA and FPG was modified by general obesity (P for interaction <0.05), with a more pronounced association observed in obese participants than in non-obese participants. Our findings suggested that pyrethroid exposure was associated with glucose dyshomeostasis. General obesity significantly heightened the association between pyrethroid exposure and increased FPG level.

Abstract P170: The Association of Urinary Cadmium and Zinc With Lower Extremity Amputations. Evidence From the Strong Heart Study

Background: Cadmium is a cardiotoxic divalent metal that accumulates in the liver and kidney. It resembles the essential metal zinc, replacing it in numerous enzymes and proteins. Zinc plays a major role in insulin function. Glucose dyshomeostasis increases the loss of zinc through the urine. Cadmium has been associated with peripheral artery disease and critical limb ischemia, conditions that lead to limb amputations. Chelation treatment with edetate disodium, an agent that facilitates the excretion of cadmium from the body, was beneficial for individuals with critical limb ischemia and diabetes in several small studies. This study evaluated the association of urinary levels of cadmium and zinc with amputations in a population with a high burden of diabetes from Arizona, Oklahoma, North Dakota and South Dakota. Hypothesis: We hypothesize that urinary cadmium and zinc levels are related to prevalent amputations in the SHS cohort. Methods: We included 2,724 participants from the Strong Heart Study, a population-based cohort study in 12 American Indian communities, recruited in 1989-1991 and followed for amputations through 1998-1999. Trained staff identified amputations of the lower extremity through visual examination at the baseline visit. We censored traumatic amputations. Baseline metal levels in spot urine samples were divided by urinary creatinine to account for urine dilution. Results: Mean age was 56.4 years, 41.5% participants were male, and 42% had diabetes. We identified a total of 35 (1.3%) amputations of the lower extremities during the study period. Median urinary levels were 0.97 μg/g for cadmium and 0.56 mg/g for zinc. Higher levels of urinary cadmium and zinc were positively associated with the presence of amputations. The odds ratios of prevalent amputations for an IQR of cadmium and zinc distribution were 1.54 (1.00, 2.38) and 2.24 (1.48, 3.39), respectively, in models adjusted for sociodemographic, lifestyle (tobacco and alcohol intake), and other factors (BMI, hypertension and diabetes status, HDL and LDL-cholesterol, and estimated glomerular filtration rate). The associations remained after further adjustment for fasting plasma glucose levels. Urinary cadmium and zinc levels were positively correlated (r=0.24, P&lt;0.001). Conclusions: Urinary cadmium and zinc were positively associated with the presence of lower extremity amputations in American Indian adults with a high burden of diabetes. These results support the current evidence of cadmium as a cardiometabolic risk factor, and the potential role of impaired zinc metabolism, reflected as increased urinary zinc excretion, in vascular complications of diabetes.

Associations of urinary 1,3-butadiene metabolite with glucose homeostasis, prediabetes, and diabetes in the US general population: Role of alkaline phosphatase

The chemical – 1,3-butadiene (BD) is a volatile organic compound ubiquitous in the environment. However, the relationships and underlying mechanisms between BD exposure and glucose dyshomeostasis and diabetes in the general population remain unclear. We sought to explore the associations of BD exposure with glucose homeostasis, prediabetes, and diabetes, as well as the role of serum alkaline phosphatase (ALP) in these associations. This study included 5092 US general residents from the National Health and Nutrition Examination Survey with measurements of urinary BD metabolite (N-Acetyl-S-(3,4-dihydroxybutyl)-L-cysteine, DHBMA) and serum ALP. Glucose homeostasis was evaluated by fasting plasma glucose (FPG), fasting serum insulin (FINS), glycohemoglobin (HbA1c), and homeostasis model assessment of insulin resistance (HOMA-IR). HOMA-IR>2.6 was considered as insulin resistance (IR). Prediabetes and diabetes were determined according to the recommendations of the American Diabetes Association. The associations of DHBMA with glucose homeostasis, prediabetes, and diabetes were assessed by linear regression models and logistic regression models. The mediating role of ALP was evaluated by mediation analysis. We observed positive dose-response relationships of DHBMA level with glucose homeostasis indices and ALP levels, as well as with the risks of prediabetes and diabetes (all P < 0.05 and/or P for trend <0.05). Each 2-fold increase in DHBMA was associated with a 1.32%, 9.20%, 0.72%, and 10.64% increase in FPG, FINS, HbA1c, and HOMA-IR, respectively (all P < 0.05). And the corresponding odds ratios (ORs) and 95% confidence intervals (CIs) for IR, prediabetes, and diabetes were 1.36 (1.14, 1.61), 1.51 (1.26, 1.83), and 1.20 (0.90, 1.61), respectively. Furthermore, increased ALP significantly mediated 15.29%–41.12% of the associations of DHBMA with glucose dyshomeostasis and increased risks of prediabetes and diabetes. Our findings indicated that BD exposure was associated with glucose dyshomeostasis and increased risks of prediabetes and diabetes. The upregulation of ALP might play a significant role in these associations.

Associations of bifenthrin exposure with glucose homeostasis and type 2 diabetes mellitus in a general Chinese population: Roles of protein carbonylation

The adverse health effects of pyrethroids exposure have attracted wide concern. We aimed to assess the associations of bifenthrin, a widely used pyrethroid, with glucose homeostasis and risk of type 2 diabetes mellitus (T2DM) and to explore the underlying mechanism. Serum bifenthrin, fasting plasma glucose (FPG), fasting plasma insulin (FPI), and plasma protein carbonyl (PCO) were determined among 3822 participants from the Wuhan-Zhuhai cohort. Glucose homeostasis was evaluated by FPG, FPI, homeostasis model assessment of insulin resistance (HOMA-IR), impaired fasting glucose (IFG), and abnormal glucose regulation (AGR). The associations of serum bifenthrin with glucose homeostasis and risk of T2DM were assessed by generalized linear models and logistic regression models. The role of PCO in the above associations was evaluated by mediation analyses. After adjusting for covariates, each 2-fold increase in serum bifenthrin was associated with a 0.21 mmol/L increase in FPG and a 5.19%, 10.49%, and 12.18% increase in FPI, HOMA-IR, and PCO levels, respectively. Monotonically elevated ORs of IFG and AGR (all P and P for trend <0.05), but not T2DM (P > 0.05) were detected to be associated with increased bifenthrin. Compared with the participants with low bifenthrin and low PCO, participants with high bifenthrin exposure and high PCO showed a 0.40 mmol/L, 11.07%, and 22.50% increase in FPG, FPI, and HOMA-IR, as well as a 119.97% and 48.88% increase in risks of IFG and AGR, respectively (P for trend <0.05). Moreover, PCO mediated 13.61%–24.98% of the serum bifenthrin-associated glucose dyshomeostasis. The study suggested that bifenthrin exposure was dose-dependently associated with glucose dyshomeostasis in the general Chinese urban adults, and these associations were exacerbated and partly mediated by PCO. Given that other pollutants were not included in this study, the effect of co-exposure of pyrethroids with multiple pollutants is necessary to be considered in future studies.

257-LB: A Novel MODY-Associated Gain-of-Function Mutation in TALK-1 Leads to Islet Dysfunction and Glucose Intolerance

The most islet-restricted and abundantly expressed K+ channel of the human ꞵ-cell, TALK-1, regulates electrical activity and glucose-stimulated insulin secretion (GSIS) . Recently we identified a gain-of-function (GOF) mutation near the pore domain of TALK-1 (Leu114Pro) that causes Maturity-Onset Diabetes of the Young (MODY) in an autosomal dominant manner, but only in a single family. To confirm TALK-1-Leu114Pro as the mutation that causes the MODY phenotype and investigate the impact of TALK-1 GOF on glucose homeostasis, a mouse model containing the TALK-1-Leu114Pro mutation was generated. Interestingly, mice with TALK-1-Leu114Pro mutation show neonatal lethality which may be due to alterations of islet hormone secretion during neonatal development (this was observed in heterozygous TALK-1-Leu114Pro C57BL/6J and homozygous TALK-1-Leu114Pro CD-1 (ICR) mice) . We first confirmed that TALK-1-Leu114Pro mutation resulted in a GOF in β-cell whole-cell K+ currents. On the ꞵ-cell plasma membrane the resulting TALK-1-Leu114Pro hyperpolarizing current blunted glucose-stimulated Ca2+ entry and subsequent Ca2+ oscillations, whereas on the endoplasmic reticulum membrane TALK-1-Leu114Pro enhanced IP3-induced Ca2+ release. TALK-1-Leu114Pro+/- islets also showed decreased GSIS and reduced plasma insulin levels in TALK-1-Leu114Pro+/- mice when compared to controls. TALK-1-Leu114Pro+/- mice exhibit a significant impairment in glucose homeostasis which is likely due to reduced islet Ca2+ influx and GSIS. However, TALK-1 activity in other islet cell types may also contribute to glucose dyshomeostasis in TALK-1-Leu114Pro+/- mice. For example, pancreatic α-cell area and islet glucagon secretion are increased TALK-1-Leu114Pro+/- mice. Taken together, these data prove that the MODY-associated TALK-1-Leu114Pro mutation disrupts glucose homeostasis and suggests that TALK-1 is an islet-restricted target for the treatment for diabetes. Disclosure A. Y. Nakhe: None. P. Dadi: None. K. E. Zaborska: None. D. Jacobson: None.

Persistent exercise fatigue and associative learning deficits in combination with transient glucose dyshomeostasis in a mouse model of Gulf War Illness

AimsTo characterize exercise fatigue, metabolic phenotype and cognitive and mood deficits correlated with brain neuroinflammatory and gut microbiome changes in a chronic Gulf War Illness (GWI) mouse model. The latter have been described in an accompanying paper [1]. Main methodsAdult male C57Bl/6N mice were exposed for 28 days (5 days/week) to pyridostigmine bromide: 6.5 mg/kg, b.i.d., P.O. (GW1) or 8.7 mg/kg, q.d., P.O. (GW2); topical permethrin (1.3 mg/kg in 100% DMSO) and N,N-diethyl-meta-toluamide (DEET 33% in 70% EtOH) and restraint stress (5 min). Exercise, metabolic and behavioral endpoints were compared to sham stress control (CON/S). Key findingsRelative to CON/S, GW2 presented persistent exercise intolerance (through post-treatment (PT) day 161), deficient associative learning/memory, and transient insulin insensitivity. In contrast to GW2, GW1 showed deficient long-term object recognition memory, milder associative learning/memory deficit, and behavioral despair. SignificanceOur findings demonstrate that GW chemicals dose-dependently determine the presentation of exercise fatigue and severity/type of cognitive/mood-deficient phenotypes that show persistence. Our comprehensive mouse model of GWI recapitulates the major multiple symptom domains characterizing GWI, including fatigue and cognitive impairment that can be used to more efficiently develop diagnostic tests and curative treatments for ill Gulf War veterans.

Carbonyl reductase 1 amplifies glucocorticoid action in adipose tissue and impairs glucose tolerance in lean mice

ObjectiveCarbonyl reductase 1 (Cbr1), a recently discovered contributor to tissue glucocorticoid metabolism converting corticosterone to 20β-dihydrocorticosterone (20β-DHB), is upregulated in adipose tissue of obese humans and mice and may contribute to cardiometabolic complications of obesity. This study tested the hypothesis that Cbr1-mediated glucocorticoid metabolism influences glucocorticoid and mineralocorticoid receptor activation in adipose tissue and impacts glucose homeostasis in lean and obese states. MethodsThe actions of 20β-DHB on corticosteroid receptors in adipose tissue were investigated first using a combination of in silico, in vitro, and transcriptomic techniques and then in vivo administration in combination with receptor antagonists. Mice lacking one Cbr1 allele and mice overexpressing Cbr1 in their adipose tissue underwent metabolic phenotyping before and after induction of obesity with high-fat feeding. Results20β-DHB activated both the glucocorticoid and mineralocorticoid receptor in adipose tissue and systemic administration to wild-type mice induced glucose intolerance, an effect that was ameliorated by both glucocorticoid and mineralocorticoid receptor antagonism. Cbr1 haploinsufficient lean male mice had lower fasting glucose and improved glucose tolerance compared with littermate controls, a difference that was abolished by administration of 20β-DHB and absent in female mice with higher baseline adipose 20β-DHB concentrations than male mice. Conversely, overexpression of Cbr1 in adipose tissue resulted in worsened glucose tolerance and higher fasting glucose in lean male and female mice. However, neither Cbr1 haploinsfficiency nor adipose overexpression affected glucose dyshomeostasis induced by high-fat feeding. ConclusionsCarbonyl reductase 1 is a novel regulator of glucocorticoid and mineralocorticoid receptor activation in adipose tissue that influences glucose homeostasis in lean mice.

Pathology, Risk Factors, and Oxidative Damage Related to Type 2 Diabetes-Mediated Alzheimer's Disease and the Rescuing Effects of the Potent Antioxidant Anthocyanin.

The pathology and neurodegeneration in type 2 diabetes- (T2D-) mediated Alzheimer's disease (AD) have been reported in several studies. Despite the lack of information regarding the basic underlying mechanisms involved in the development of T2D-mediated AD, some common features of the two conditions have been reported, such as brain atrophy, reduced cerebral glucose metabolism, and insulin resistance. T2D phenotypes such as glucose dyshomeostasis, insulin resistance, impaired insulin signaling, and systemic inflammatory cytokines have been shown to be involved in the progression of AD pathology by increasing amyloid-beta accumulation, tau hyperphosphorylation, and overall neuroinflammation. Similarly, oxidative stress, mitochondrial dysfunction, and the generation of advanced glycation end products (AGEs) and their receptor (RAGE) as a result of chronic hyperglycemia may serve as critical links between diabetes and AD. The natural dietary polyflavonoid anthocyanin enhances insulin sensitivity, attenuates insulin resistance at the level of the target tissues, inhibits free fatty acid oxidation, and abrogates the release of peripheral inflammatory cytokines in obese (prediabetic) individuals, which are responsible for insulin resistance, systemic hyperglycemia, systemic inflammation, brain metabolism dyshomeostasis, amyloid-beta accumulation, and neuroinflammatory responses. In this review, we have shown that obesity may induce T2D-mediated AD and assessed the recent therapeutic advances, especially the use of anthocyanin, against T2D-mediated AD pathology. Taken together, the findings of current studies may help elucidate a new approach for the prevention and treatment of T2D-mediated AD by using the polyflavonoid anthocyanin.

Copper Ionophores as Novel Antiobesity Therapeutics.

The therapeutic utility of the copper ionophore disulfiram was investigated in a diet-induced obesity mouse model (C57BL/6J background), both through administration in feed (0.05 to 1% (w/w)) and via oral gavage (150 mg/kg) for up to eight weeks. Mice were monitored for body weight, fat deposition (perigonadal fat pads), metabolic changes (e.g., glucose dyshomeostasis) and pathologies (e.g., hepatic steatosis, hyperglycaemia and hypertriglyceridemia) associated with a high-fat diet. Metal-related pharmacological effects across major organs and serums were investigated using inductively coupled plasma mass spectrometry (ICP-MS). Disulfiram treatments (all modes) augmented hepatic copper in mice, markedly moderated body weight and abolished the deleterious systemic changes associated with a high-fat diet. Likewise, another chemically distinct copper ionophore H2(gtsm), administered daily (oral gavage), also augmented hepatic copper and moderated mouse body weight. Postmortem histological examinations of the liver and other major organs, together with serum aminotransferases, supported the reported therapeutic safety of disulfiram. Disulfiram specifically altered systemic copper in mice and altered hepatic copper metabolism, perturbing the incorporation of copper into ceruloplasmin (holo-ceruloplasmin biosynthesis) and subsequently reducing serum copper concentrations. Serum ceruloplasmin represents a biomarker for disulfiram activity. Our results establish copper ionophores as a potential class of antiobesity agents.