Glucose Tolerance In Male Mice Research Articles

Inhibition of mammalian mtDNA transcription acts paradoxically to reverse diet-induced hepatosteatosis and obesity.

The oxidative phosphorylation system1 in mammalian mitochondria plays a key role in transducing energy from ingested nutrients2. Mitochondrial metabolism is dynamic and can be reprogrammed to support both catabolic and anabolic reactions, depending on physiological demands or disease states. Rewiring of mitochondrial metabolism is intricately linked to metabolic diseases and promotes tumour growth3-5. Here, we demonstrate that oral treatment with an inhibitor of mitochondrial transcription (IMT)6 shifts whole-animal metabolism towards fatty acid oxidation, which, in turn, leads to rapid normalization of body weight, reversal of hepatosteatosis and restoration of normal glucose tolerance in male mice on a high-fat diet. Paradoxically, the IMT treatment causes a severe reduction of oxidative phosphorylation capacity concomitant with marked upregulation of fatty acid oxidation in the liver, as determined by proteomics and metabolomics analyses. The IMT treatment leads to a marked reduction of complex I, the main dehydrogenase feeding electrons into the ubiquinone (Q) pool, whereas the levels of electron transfer flavoprotein dehydrogenase and other dehydrogenases connected to the Q pool are increased. This rewiring of metabolism caused by reduced mtDNA expression in the liver provides a principle for drug treatment of obesity and obesity-related pathology.

Hepatic lipid droplet-associated proteome changes distinguish dietary-induced fatty liver from glucose tolerance in male mice.

Fatty liver is characterized by the expansion of lipid droplets (LDs) and is associated with the development of many metabolic diseases. We assessed the morphology of hepatic LDs and performed quantitative proteomics in lean, glucose-tolerant mice compared to high-fat diet (HFD) fed mice that displayed hepatic steatosis and glucose intolerance as well as high-starch diet (HStD) fed mice who exhibited similar levels of hepatic steatosis but remained glucose tolerant. Both HFD and HStD-fed mice had more and larger LDs than Chow-fed animals. We observed striking differences in liver LD proteomes of HFD and HStD-fed mice compared to Chow-fed mice, with fewer differences between HFD and HStD. Taking advantage of our diet strategy, we identified a fatty liver LD proteome consisting of proteins common in HFD- and HStD-fed mice, as well as a proteome associated with glucose tolerance that included proteins shared in Chow and HStD but not HFD-fed mice. Notably, glucose intolerance was associated with changes in the ratio of adipose triglyceride lipase to perilipin 5 in the LD proteome, suggesting dysregulation of neutral lipid homeostasis in glucose-intolerant fatty liver. We conclude that our novel dietary approach uncouples ectopic lipid burden from insulin resistance-associated changes in the hepatic lipid droplet proteome.

Adipocyte Subpopulations Mediate Growth Hormone-induced Lipolysis and Glucose Tolerance in Male Mice.

In adipose tissue, growth hormone (GH) stimulates lipolysis, leading to an increase in plasma free fatty acid levels and a reduction in insulin sensitivity. In our previous studies, we have found that GH increases lipolysis by reducing peroxisome proliferator-activated receptor γ (PPARγ) transcription activity, leading to a reduction of tat-specific protein 27 (FSP27, also known as CIDEC) expression. In previous studies, our laboratory uncovered 3 developmentally distinct subpopulations of white adipocytes. In this manuscript, we show that one of the subpopulations, termed type 2 adipocytes, has increased GH-induced signaling and lipolysis compared to other adipocyte subtypes. To assess the physiological role of GH-mediated lipolysis mediated by this adipocyte subpopulation, we specifically expressed human FSP27 (hFSP27) transgene in type 2 adipocytes (type2Ad-hFSP27tg mice). Systemically, male type2Ad-hFSP27tg mice displayed reduced serum glycerol release and nonesterified fatty acids levels after acute GH treatment, and improvement in acute, but not chronic, GH-induced glucose intolerance. Furthermore, we demonstrate that type2Ad-hFSP27tg mice displayed improved hepatic insulin signaling. Taken together, these results indicate that this adipocyte subpopulation is a critical regulator of the GH-mediated lipolytic and metabolic response. Thus, further investigation of adipocyte subpopulations may provide novel treatment strategies to regulate GH-induced glucose intolerance in patients with growth and metabolic disorders.

295-LB: Pancreatic Peroxisomes Are Required for Physiological Regulation of Insulin Secretion and Maintenance of Normal Glucose Tolerance in Male Mice

The regulation of glucose-stimulated insulin secretion (GSIS) is central to maintenance of glucose disposal. The role of lipid storage and lipid oxidation to regulate pancreatic islet β-cell insulin secretion is not completely understood. Peroxisomes are enriched in insulin-producing β-cells, but their contribution to β-cell function and maturity is lacking. Therefore, we generated a novel model of peroxisomal dysfunction to test the hypothesis that peroxisomal lipid metabolism is required to prevent a hyperlipidemic environment that interferes with β-cell function and maturity. Pex5 plays a critical role in importing the majority of peroxisomal proteins into the peroxisomal matrix; thus, deletion of the Pex5 gene creates a cellular environment with reductions in function of this organelle. In this study, we bred Pex5 mice on a C57BL/6J background containing ‘floxed’ alleles to Pdx1-cre mice to generate offspring with a pancreas-wide deficiency in Pex5 expression and abundance. Glucose tolerance was impaired by 12 weeks in male mice (n=20; AUC p<0.05). Surprisingly, GSIS was elevated in Pex5Pdx1-/- mice compared to littermate controls both in vivo (n=15; AUC p<0.05) and ex vivo in isolated islets as measured by perifusion analysis (n=12; AUC p<0.01). We further found that a subset of β-cells from Pex5Pdx1-/- mice expressed the de-differentiation marker Aldh1a3, while a subset of β-cells showed reductions in MafA and Nkx6.1 staining compared to controls. Perilipin-1 staining showed increased presence of lipid droplets in pancreatic tissue of Pex5Pdx1-/- mice versus controls. Thus, pancreatic deletion of peroxisomal function results in increased lipid storage in pancreatic tissue that is correlated with exaggerated insulin secretion. Collectively, these data are in support of a model whereby peroxisomal function supports β-cell insulin secretion and maintenance of the fully differentiated state. Disclosure S. Burke: None. S. Ghosh: None. D. Burk: None. R. Noland: None. J. Collier: None.

1538-P: Brain TGFß Regulates Glucose Tolerance in Male Mice with Metabolic Syndrome

Hypothalamic inflammation contributes to insulin resistance and obesity. Transforming growth factor beta (TGFβ) is among the inflammatory mediators inducing hypothalamic inflammation. In this study, we investigated the role of brain TGFβ on metabolic function. We hypothesized that TGFβ in the brain promotes insulin resistance and reduces glucose tolerance in diabetic and obese mice. C57BL/J male mice were fed either hypercaloric diet (HCD, 52% fat) or regular diet (RD) from weaning. At 3 months age, intraperitoneal glucose tolerance test (GTT), insulin tolerance test (ITT) and weight confirmed the acquisition of metabolic syndrome. Hypothalamic protein expression was assessed for TGFβ receptor 2, phosphorylated SMAD3, SMAD6 and SMAD7, as downstream signal transducer proteins for TGFβ. Compared to RD male mice (n=6), mice on HCD (n=6) showed glucose intolerance (AUC; 60587 ±2460 vs. 30802±1923, p<0.0001), insulin intolerance (AUC; Mean±SEM; 19025836.0 vs.11436±1087, p=0.02) and weight gain (33.67±2.028 vs. 26.89±0.4231 g). HCD mice also exhibited increased protein levels of TGFβR2 (normalized to total protein, Fold Change (FC)±SEM to RD group; 3.54±0.3, p<0.0001), pSMAD3 (FC 2±0.5, p=0.04) while inhibitors for TGFβ signaling such as SMAD6 and SMAD7, were downregulated (FC 0.7±0.1, p=0.03 and 0.8±0.04, p=0.03, respectively). To understand the role of brain TGFβ on metabolic regulation, 3 months HCD mice were subjected to intracerebroventricular (ICV) infusion with either TGFβ neutralizing antibody (nAb, n=4) or IgG control antibody (n=4) using subcutaneous osmotic pumps connected to ICV cannula for 2 weeks. GTT was measured after 2-week infusion. Treatment with TGFβ nAb resulted in lower fasting blood glucose compared to before treatment (166.1 ±6.878 vs. 229.9 ±3.923 mg/dL) and at 120 min time point (229.9 ±28.69 vs. 382.2 ±24.33 mg/dL). In conclusion, brain TGFβ plays a key role in regulating glucose metabolism probably through inflammation-induced insulin resistance. Disclosure M.Elgazzaz: None. K.Miao: None. A.R.Nuzzo: None. L.Restivo: None. K.Moles: None. E.D.Lazartigues: None. Funding American Diabetes Association (1-19-IBS-291 to E.D.L.)

Gabra5 plays a sexually dimorphic role in POMC neuron activity and glucose balance.

Pro-opiomelanocortin (POMC) neurons are important for the regulation of body weight and glucose balance. The inhibitory tone to POMC neurons is mediated primarily by the GABA receptors. However, the detailed mechanisms and functions of GABA receptors are not well understood. The α5 subunit of GABAA receptor, Gabra5, is reported to regulate feeding, and we found that Gabra5 is highly expressed in POMC neurons. To explore the function of Gabra5 in POMC neurons, we knocked down Gabra5 specifically from mature hypothalamic POMC neurons using the clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 strategy. This POMC-specific knock-down of Gabra5 did not affect body weight or food intake in either male or female mice. Interestingly, the loss of Gabra5 caused significant increases in the firing frequency and resting membrane potential, and a decrease in the amplitude of the miniature inhibitory postsynaptic current (mIPSC) in male POMC neurons. However, the loss of Gabra5 only modestly decreased the frequency of mIPSC in female POMC neurons. Consistently, POMC-specific knock-down of Gabra5 significantly improved glucose tolerance in male mice but not in female mice. These results revealed a sexually dimorphic role of Gabra5 in POMC neuron activity and glucose balance, independent of body weight control.

1319-P: Gabra5 Plays a Sexually Dimorphic Role in POMC Neuron Activity and Glucose Balance

Pro-opiomelanocortin (POMC) neurons are important for body weight and glucose balance. The inhibitory tone to POMC neurons is mediated primarily by GABA receptor complex. However, the detailed mechanisms and functions of GABA receptors are not well understood. We found that α5 subunit of GABA receptor complex, Gabra5, is highly expressed in POMC neurons. To explore the function of Gabra5 in POMC neurons, we deleted Gabra5 specifically from mature POMC neurons using the CRISPR-Cas9 strategy. Body weight and food intake were not affected in either male mice or female mice by the deletion of Gabra5 from POMC neurons. We found that the deletion of Gabra5 caused a significant increase in the firing frequency and rest membrane potential, and a decrease in the amplitude of mIPSC in male POMC neurons. However, the deletion of Gabra5 just modestly decreased the frequency of mIPSC in female POMC neurons. Consistently, loss of Gabra5 from POMC neurons significantly improved the glucose tolerance in male mice but not in female mice. These results revealed a sexually dimorphic role of Gabra5 in POMC neuron activity and glucose balance, independent of body weight control. Disclosure Z.Pei: None. Y.He: None. Y.He: None. Y.Xu: None. C.Wang: None. Funding National Institutes of Health (KDK119471)

Mapping and specific viral targeting of peripheral pancreatic innervation

Neuronal inputs from central nervous system (CNS) are essential in regulating pancreatic endocrine function. It has been shown that perturbation of CNS activity alters pancreatic hormone release. CNS and peripheral organs constantly communicate through the peripheral nervous system (PNS), which can be divided into autonomic efferent (parasympathetic and sympathetic) and afferent sensory nervous systems. While we know that the pancreas is densely innervated by the PNS, we lack a comprehensive map of peripheral ganglia providing inputs to the pancreas. These data could provide crucial information about pancreatic function. Published studies suggest parasympathetic inputs to the pancreas lower blood glucose by enhancing insulin secretion. On the other hand, sympathetic action results in increased blood glucose levels by stimulating glucagon secretion and inhibiting insulin. However, these studies are based on electrical stimulation or transection of peripheral splachnic and vagal nerves that may affect the activity of other metabolically active organs (liver, stomach, intestine,). Highly targeted modulation of specific pancreatic nerve activity in health and pancreatic diseases requires new approaches.In the present project, we provide a detailed map of the distribution of peripheral pancreas‐innervating neurons using retrograde tracing, tissue clearing and 3D imaging techniques (Idisco+). We show that a substantial pancreatic innervation (Fig 1b) with significant neuronal populations in sympathetic, parasympathetic and sensory ganglia projecting to pancreatic tissue (Fig 1 c,d). In addition, we achieved targeted gene delivery to specific pancreatic efferent and afferent pathways by optimizing adeno‐associated viral serotypes (AAV), promoters, titers and delivery (Fig2 a‐d). By utilizing our optimized approach, we show that highly targeted chemogenetic neural activation of intrapancreatic parasympathetic cholinergic neurons increased plasma insulin and significantly improved glucose tolerance in male mice (Fig 2 e,f). Additionally, using a dual viral strategy to specifically target pancreas‐projecting sympathetic neurons, we demonstrated that targeted activation of pancreas‐projecting sympathetic neurons impaired glucose tolerance in male mice (Fig 2g,h).Our innovative viral approaches allow highly targeted gene expression and neuromodulation of defined pancreatic nerves. These methodologies will allow examination of functional roles of pancreatic parasympathetic and sympathetic innervation in glucose metabolism as well as in digestion (exocrine function). Our work also allow for future studies to determine the specific contribution of pancreatic innervation to metabolic diseases, pancreatic inflammation and cancer.

Soat2 ties cholesterol metabolism to β-oxidation and glucose tolerance in male mice.

Sterol O-acyltransferase 2 (Soat2) encodes acyl-coenzyme A:cholesterol acyltransferase 2 (ACAT2), which synthesizes cholesteryl esters in hepatocytes and enterocytes fated either to storage or to secretion into nascent triglyceride-rich lipoproteins. We aimed to unravel the molecular mechanisms leading to reduced hepatic steatosis when Soat2 is depleted in mice. Soat2-/- and wild-type mice were fed a high-fat, a high-carbohydrate, or a chow diet, and parameters of lipid and glucose metabolism were assessed. Glucose, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), oral glucose tolerance (OGTT), and insulin tolerance tests significantly improved in Soat2-/- mice, irrespective of the dietary regimes (2-way ANOVA). The significant positive correlations between area under the curve (AUC) OGTT (r = 0.66, p < 0.05), serum fasting insulin (r = 0.86, p < 0.05), HOMA-IR (r = 0.86, p < 0.05), Adipo-IR (0.87, p < 0.05), hepatic triglycerides (TGs) (r = 0.89, p < 0.05), very-low-density lipoprotein (VLDL)-TG (r = 0.87, p < 0.05) and the hepatic cholesteryl esters in wild-type mice disappeared in Soat2-/- mice. Genetic depletion of Soat2 also increased whole-body oxidation by 30% (p < 0.05) compared to wild-type mice. Our data demonstrate that ACAT2-generated cholesteryl esters negatively affect the metabolic control by retaining TG in the liver and that genetic inhibition of Soat2 improves liver steatosis via partitioning of lipids into secretory (VLDL-TG) and oxidative (fatty acids) pathways.

1243-P: The Chd4 Helicase Regulates Pdx1-Controlled Genes Involved in ß-Cell Function

Diabetes progression is partly characterized by a loss of key transcription factors (TFs) in a subset of failing β-cells. Among these TFs is Pdx1, which coordinates the expression of numerous genes related to β-cell function (MafA, Ins2, Ucn3), mitochondrial function (Tfam), and calcium signaling (Cacna1d, Camkk2, Atp2a2). Pdx1 requires the recruitment of transcriptional coregulators to modulate its activity and has recently been shown to interact with the Chd4 ATPase subunit of the Nucleosome Remodeling and Deacetylase complex. In other cellular contexts, Chd4 is required to maintain cellular identity and mitochondrial function; however, the contribution of Chd4 in controlling Pdx1-target genes in the β-cell has yet to be explored. Here, we confirmed the Pdx1:Chd4 interaction using co-IP in mouse β-cell lines and proximity ligation assay in mouse and human β-cell lines and tissue. We found, by ChIP-Sequencing, that Chd4 binds to 4796 genes in β-cell lines, 4463 of which are also bound by Pdx1, including MafA, Cacna1d, and Atp2a2. Transient siRNA knockdown of Chd4 in the βTC-3 murine insulinoma cell line led to a reduction of MafA at the transcript (41% ± 3, p &amp;lt; 0.05) and protein level, as well as reduced expression of mitochondrial TF Tfam (39% ± 8, p &amp;lt;0.05) and calcium regulators Camkk2 (53% ± 6, p &amp;lt;0.05) and Serca2b (51% ± 13, p &amp;lt;0.05). Furthermore, glucose-stimulated insulin secretion in the INS1 832/13 rat insulinoma cell line was impaired (p = 0.0504) in Chd4 knockdown cells. We next generated a tamoxifen-inducible, β-cell-specific (MIP-CreERT) mouse knockout line of Chd4 and found significant impairment in glucose tolerance in male mice 2 weeks post-tamoxifen. Together, these data indicate Chd4 is required for the expression of numerous Pdx1-controlled genes important for β-cell function and whole-body glucose homeostasis. Future efforts are focused on defining the contributions of Chd4 in regulating gene expression and chromatin accessibility in β-cells using our β-cell-specific Chd4 knockout model. Disclosure R. K. Davidson: None. N. Casey: None. S. Kanojia: None. J. Spaeth: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases (K01DK115633)

Allelic insufficiency of Znt8 had improved glucose tolerance in male mice after high fat intake

Zinc transporter 8 (ZNT8) is mainly expressed in the pancreatic β‐cell. ZNT8 transports zinc from the cytosol into the insulin‐containing secretory vesicle for insulin crystallization and secretion. Reduced ZNT8 expression affects glucose‐stimulated insulin secretion. Genome Wide‐Association Studies revealed that people with one null allele of ZNT8 are 65% less likely to develop type 2 diabetes (T2D) than those with two normal alleles. The molecular mechanism underling this protective function of ZNT8 allelic insufficiency is not clear. Our specific aim was to uncover this mechanism using Znt8+/− mice. We hypothesized that Znt8 allelic insufficiency caused a decrease in glucose‐stimulated insulin secretion which triggered a compensatory action that ensured normal blood glucose levels after a meal. In the current study, we fed Znt8+/− and control mice a high‐fat diet to induce insulin resistance. The results from this study suggest a gender‐dependent role of Znt8 allelic insufficiency in the protection of mice from T2D. We found that male mice were benefited from Znt8 heterozygosity for controlling glucose levels whereas Znt8 heterozygosity helped female mice for handling dietary lipids. Importantly, we found that glucagon may play a key role in controlling glucose levels in Znt8+/− mice. In conclusion, our data support the notion that allelic Znt8 insufficiency can provide a protective effect against diet‐induced glucose intolerance, possibly through regulation of glucagon secretion.Support or Funding InformationUSDA/ARS 2032‐51000‐005‐00D.

Dietary Supplementation with Galactooligosaccharides Attenuates High-Fat, High-Cholesterol Diet-Induced Glucose Intolerance and Disruption of Colonic Mucin Layer in C57BL/6 Mice and Reduces Atherosclerosis in Ldlr–/– Mice

BackgroundA Western-type diet (WD), rich in fat and cholesterol but deficient in fiber, induces development of diabetes and atherosclerosis. Colonic bacteria use the gut's mucous lining as an alternate energy source during periods of fiber deficiency, resulting in intestinal barrier erosion. ObjectiveWe hypothesized that supplementing a WD with galactooligosaccharide (GOS) fiber would attenuate WD-induced mucin layer disruption and attenuate development of metabolic diseases. MethodsC57BL/6 mice (both sexes, 8–10 wk of age) were fed a standard rodent diet (TD7012, reference) or a high-fat, high-cholesterol–containing WD (TD88137, 21% fat, 0.15% cholesterol, 19.5% caesin) or a WD supplemented with 5% GOS fiber (TD170432, WD + GOS) for 16 wk. WD-fed mice that were gavaged daily with curcumin (100 mg/kg) served as positive controls. Glucose tolerance, colonic mucin layer, gene expression, and circulating macrophage/neutrophil levels were determined. Hyperlipidemic Ldlr–/– mice (both sexes, 8–10 wk of age) fed a WD with or without GOS supplementation (for 16 wk) were used to assess plasma LPS and atherosclerosis. Effects of dietary supplementation on different parameters were compared for each genotype. ResultsCompared with a WD, glucose tolerance was significantly improved in male C57BL/6 mice fed a WD + GOS (mean ± SEM: AUC = 53.6 ± 43.9 compared with 45.4 ± 33.3 g · min/dL; P = 0.015). Continuity of colonic mucin layer (MUC-2 expression) was improved in mice receiving GOS supplementation, indicating improved intestinal barrier. GOS supplementation also reduced circulating macrophages (30% decrease) and neutrophils (60% decrease), suggesting diminished systemic inflammation. In Ldlr–/– mice, GOS supplementation significantly reduced plasma LPS concentrations (mean ± SEM: 0.81 ± 0.43 EU/mL compared with 0.32 ± 0.26 EU/mL,P < 0.0001, in females and 0.56 ± 0.24 EU/mL compared with 0.34 ± 0.12 EU/mL, P = 0.036, in males), improved glucose tolerance in male mice, and attenuated atherosclerotic lesion area (mean ± SEM: 54.2% ± 6.19% compared with 43.0% ± 35.12%, P = 0.0006, in females and 54.6% ± 3.99% compared with 43.1% ± 8.11%, P = 0.003, in males). ConclusionsGOS fiber supplementation improves intestinal barrier in C57BL/6 and Ldlr–/– mice and significantly attenuates WD-induced metabolic diseases and, therefore, may represent a novel strategy for management of these diseases.

Aromatase deficiency in hematopoietic cells improves glucose tolerance in male mice through skeletal muscle-specific effects.

Estrogens are important for maintaining metabolic health in males. However, the key sources of local estrogen production for regulating energy metabolism have not been fully defined. Immune cells exhibit aromatase activity and are resident in metabolic tissues. To determine the relative contribution of immune cell-derived estrogens for metabolic health in males, C57BL6/J mice underwent bone marrow transplant with marrow from either wild-type (WT(WT)) or aromatase-deficient (WT(ArKO)) donors. Body weight, body composition, and glucose and insulin tolerance were assessed over 24 weeks with mice maintained on a regular chow diet. No differences were found in insulin sensitivity between groups, but WT(ArKO) mice were more glucose tolerant than WT(WT) mice 20 weeks after transplant, suggestive of enhanced glucose disposal (AUCglucose 6061±3349 in WT(WT) mice versus 3406±1367 in WT(ArKO) mice, p = 0.01). Consistent with this, skeletal muscle from WT(ArKO) mice showed higher expression of the mitochondrial genes Ppargc1a (p = 0.03) and Nrf1 (p = 0.01), as well as glucose transporter type 4 (GLUT4, Scl2a4; p = 0.02). Skeletal muscle from WT(ArKO) mice had a lower concentration of 17β-estradiol (5489±2189 pg/gm in WT(WT) mice versus 3836±2160 pg/gm in WT(ArKO) mice, p = 0.08) but higher expression of estrogen receptor-α (ERα, Esr1), raising the possibility that aromatase deficiency in immune cells led to a compensatory increase in ERα signaling. No differences between groups were found with regard to body weight, adiposity, or gene expression within adipose tissue or liver. Immune cells are a key source of local 17β-estradiol production and contribute to metabolic regulation in males, particularly within skeletal muscle. The respective intracrine and paracrine roles of immune cell-derived estrogens require further delineation, as do the pathways that regulate aromatase activity in immune cells specifically within metabolic tissues.

Gender specific effects of Nr4a1 on functional β‐cell mass

Nuclear hormone receptor4a1 (Nr4a1) plays a critical role in β‐cell replication, function, and survival. β‐cell replication is tightly regulated, most β‐cells in the body are formed during development and shortly after birth. Nr4a1 full body knock‐out mice have a 50% reduction in total β‐cell area. Nr4a1 knock down INS‐1 832/13 β‐cells have decreased mitochondrial respiration, glucose stimulated insulin secretion and cellular proliferation. Fatty acids regulate Nr4a1 activity and expression. Here we present the effects of β‐cell specific Nr4a1 deletion on mice exposed to a high fat or normal chow diet beginning at 3‐months of age. Our data demonstrate that loss of β‐cell Nr4a1 results in improved non‐fasting blood glucose and glucose tolerance in male mice fed a high fat diet for 4 months. Interestingly, female mice deficient for Nr4a1 have impaired glucose tolerance as early as 1 months of high fat feeding. Furthermore, we show data regarding β‐cell mass and glucose stimulated insulin secretion. These data demonstrate a clear gender bias in Nr4a1 function in the β‐cell.Support or Funding InformationADA 1‐17‐IBS‐101 to JSTThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Reduced body weight at weaning followed by increased post-weaning growth rate interacts with part-per-trillion fetal serum concentrations of bisphenol A (BPA) to impair glucose tolerance in male mice.

There is evidence from longitudinal studies that being light at birth and weaning is associated with subsequent rapid weight gain in infants. This is referred to as “centile crossing”, which can lead to increased risk of lifetime obesity, glucose dysregulation and type 2 diabetes. Here, pregnant CD-1 mice were hemi-ovariectomized so that the entire litter was contained in one uterine horn to increase variability in fetal growth rate. Pregnant females were implanted on gestation day (GD) 9 with a Silastic capsule containing 6, 60 or 600 μg bisphenol A (BPA). On GD 18 the mean fetal serum unconjugated BPA concentrations were 17, 177 and 1858 pg/ml, respectively. Capsules were not removed, to avoid maternal stress, and were predicted to release BPA for at least 3 weeks. Body weight at weaning was strongly negatively correlated with post-weaning weight gain in both control and BPA-treated male mice, consistent with human data; female offspring were excluded, avoiding complications associated with postpubertal estrogens. Within each treatment group, male offspring were sorted into tertiles based on relative weight gain during the two weeks after weaning, designated as having Rapid (R), Medium (M) or Slow (S) growth rate. BPA exposure was associated with altered growth rate between weaning and postnatal week 12 (young adulthood), when a low-dose (20 mg/kg, i.p.) glucose tolerance test (GTT) was performed. We found altered glucose regulation in response to all doses of BPA. However, glucose tolerance was only significantly impaired (blood glucose levels were elevated) compared to controls in males in the rapid post-weaning growth group exposed perinatally to BPA. We conclude that male mice that are light at weaning, but then experience rapid catch-up growth immediately after weaning, represent a sensitive sub-population that is vulnerable to the metabolic disrupting effects of very low pg/ml fetal serum concentrations of BPA.

Relation between type 2 diabetes and m.1382 A&gt;C polymorphism which occurs amino acid replacement (K14Q) of mitochondria‐derived MOTS‐c

IntroductionThe onset of type 2 diabetes is influenced by genetic background. However, it is not well defined. Low mitochondrial function has been related to insulin resistance. Recently, Lee et al. (Cell Metabolism, 2015) reported that mitochondrial derived peptide mitochondrial open‐reading‐frame of the twelve s rRNA –c (MOTS‐c) enhances muscular insulin sensitivity in mice. Actually, MOTS‐c which comprises 16 amino acid residues, also circulates in human blood. We have more recently reported that East Asian specific m.1382 A&gt;C polymorphism accompanies amino acid replacement from Lys (K) to Gln (Q) at the 14th amino‐acid residue of the MOTS‐c (Fuku et al., Aging Cell, 2015). However, the relation between m.1382 A&gt;C polymorphism and type 2 diabetes remain unknown. Therefore, we hypothesized that amino acid replacement (K14Q) of the MOTS‐c by m.1382 A&gt;C polymorphism affects the onset of type 2 diabetes because of changing insulin sensitivity on the skeletal muscle and/or liver in East Asian populations.AimThis study was conducted to clarify the relation between type 2 diabetes and m.1382 A&gt;C polymorphism [MOTS‐c (K14Q)] in Japanese individuals and to investigate the effect of MOTS‐c amino acid replacement (K14Q) on glucose metabolism.Methods and ResultsStudy 1: Prevalence of type 2 diabetes in m.1382A&gt;C genotype of JapaneseThis study examined 12, 069 community‐dwelling Japanese individuals (5078 men and 6991 women; aged 40–69 years). m.1382 A&gt;C genotype was determined using Luminex methods. Physical activity of participants was measured using an accelerometer. Results showed that type 2 diabetes in men (11.0%) was more prevalent than women (4.6%). A tendency relation was found between m.1382 A&gt;C polymorphism and prevalence of type 2 diabetes in men. Subjects with C allele had a higher prevalence of type 2 diabetes than those with A allele (P = .20). However, no relation was found for women. Because moderate to vigorous intensity physical activity (MVPA) alters type 2 diabetes in men, we combined analyses MVPA and m.1382 A&gt;C genotype. In the lowest tertile of MVPA, subjects with C allele had a significantly higher prevalence of type 2 diabetes than those with A allele in men (C allele, 18.5%; A allele, 11.2%; odds ratio = 1.8 (95% CI: 1.1–2.9; P = .02).Study 2: Effect of MOTS‐c [K/Q14] on glucose tolerance test in miceTen‐week old male C57BL/6 J mice were used for this experiment. We used two synthetic MOTS‐c peptides: K14 (wild type) and Q14 (mutant type). For glucose tolerance tests, mice were treated with MOTS‐c [K14] (0.5 mg/kg/day; IP), MOTS‐c [Q14] (0.5 mg/kg/day; IP), or vehicle (equal volume; IP), daily for 7 days. Then mice were injected with D‐glucose (1 g/kg; IP). Blood was sampled from the tail at 0, 15, 30, 45, 60, 90, and 120 min post‐glucose injection. Preliminary results of glucose tolerance tests showed MOTS‐c [K14] enhanced murine glucose clearance compared to vehicle. However, MOTS‐c [Q14] did not enhance glucose clearance.ConclusionEpidemiological studies have revealed that m.1382 A&gt;C polymorphism is associated with type 2 diabetes with lower MVPA in men, but not in women An animal model showed that MOTS‐c amino acid replacement (K14Q) affects glucose tolerance in male mice. Taken together, these results suggest that MOTS‐c amino acid replacement (K14Q) by m.1382 A&gt;C polymorphism may influence prevalence of type 2 diabetes.

Central Adiponectin Acutely Improves Glucose Tolerance in Male Mice

Adiponectin, an adipocyte-derived hormone, regulates glucose and lipid metabolism. It is also antiinflammatory. During obesity, adiponectin levels and sensitivity are reduced. Whereas the action of adiponectin in the periphery is well established the neuroendocrine role of adiponectin is largely unknown. To address this we analyzed the expression of adiponectin and the 2 adiponectin receptors (AdipoR1 and AdipoR2) in response to fasting and to diet-induced and genetic obesity. We also investigated the acute impact of adiponectin on central regulation of glucose homeostasis. Adiponectin (1 μg) was injected intracerebroventricularly (ICV), and glucose tolerance tests were performed in dietary and genetic obese mice. Finally, the influence of ICV adiponectin administration on central signaling cascades regulating glucose homeostasis and on markers of hypothalamic inflammation was assessed. Gene expression of adiponectin was down-regulated whereas AdipoR1 was up-regulated in the arcuate nucleus of fasted mice. High-fat (HF) feeding increased AdipoR1 and AdipoR2 gene expression in this region. In mice on a HF diet and in leptin-deficient mice acute ICV adiponectin improved glucose tolerance 60 minutes after injection, whereas normoglycemia in control mice was unaffected. ICV adiponectin increased pAKT, decreased phospho-AMP-activated protein kinase, and did not change phospho-signal transducer and activator of transcription 3 immunoreactivity. In HF-fed mice, ICV adiponectin reversed parameters of hypothalamic inflammation and insulin resistance as determined by the number of phospho-glycogen synthase kinase 3 β(Ser9) and phospho-c-Jun N-terminal kinase (Thr183/Tyr185) immunoreactive cells in the arcuate nucleus and ventromedial hypothalamus. This study demonstrates that the insulin-sensitizing properties of adiponectin are at least partially based on a neuroendocrine mechanism that involves centrally synthesized adiponectin.

Adaptations to the loss of intestinal fatty acid binding protein in mice

It was shown previously that the intestinal fatty acid binding protein (I-FABP) is not essential for the absorption of dietary fat. One notable feature of I-FABP deficiency was the enhancement of body weight gain in male mice but not in female mice. To explore a possible cause for this gender dimorphic effect, we examined the changes in expression of genes that encode liver fatty acid binding protein (L-FABP) and ileal lipid binding protein in the small intestine resulting from I-FABP deficiency. The results indicate that both L-FABP and ilbp levels are modestly increased in the small intestine of chow-fed mice lacking I-FABP. There was no discernible alteration of overall morphology or histology in the small intestine but changes in liver histology were evident in I-FABP deficient male mice. Glucose tolerance was also investigated in aged mice. I-FABP deficiency had no effect on glucose tolerance in male mice but it appeared to be improved in female mice. Thus, male and female mice clearly respond differently to the loss of I-FABP from the small intestine but the observed changes in the abundance of L-FABP and ilbp protein do not readily account for this phenomenon.