Circulating Insulin Concentrations Research Articles

74 Feeding style and its influence on growth, circulating insulin, and spatial preference of young pigs

Abstract In this study, we investigated the influence of feeding style on growth performance, circulating insulin concentrations, and spatial preference within the home-cages (HC) of young pigs. Pigs (n = 43 boars) were weaned on postnatal day (PND) 2, allotted to treatment based on litter of origin and body weight (BW), and reared artificially over a 15-d period. Pigs were provided a nutritionally adequate milk replacer 20 h per day using one of two feeding styles: 1) ad libitum (i.e., continual access to milk replacer), and 2) prescribed [330 mL/kg of BW from PND 3-7 (wk 1), and 357.5 mL/kg of BW from PND 8-18 (wk 2)]. In addition to water in the reconstituted milk replacer, free choice access to fresh water was provided throughout the study. Milk intake (i.e., disappearance) and BW were recorded daily, with pigs undergoing continuous top-down video surveillance throughout the study. On PND 17, blood was collected from a subset of pigs (n = 24) for quantification of insulin concentrations. Video analysis of pigs (n = 43) was performed to establish time spent in each HC quadrant. All data were analyzed via a 1-way ANOVA using the MIXED procedure of SAS. During wk 1, ad libitum pigs exhibited increased (P < 0.05) average daily BW gain (152 g/d) and average daily milk intake (728 g/d) compared with the prescribed treatment (127 g/d and 570 g/d, respectively). This same effect continued in wk 2 for average daily BW gain and average daily milk intake, with ad libitum-fed pigs consuming more (P < 0.05) milk replacer (256 g/d and 1,356 g/d, respectively) compared with prescribed-fed pigs (192 g/d and 974 g/d, respectively). Over the entire 15-d feeding study, average daily BW gain (234 g/d), average daily feed intake (1,140 g/d) and milk intake-to-BW ratio (4.60) were greater (P < 0.05) in the ad libitum treatment compared with prescribed feeding (180 g/d, 830 g/d, and 3.81 respectively). Insulin concentrations were greater (P < 0.05) in the ad libitum treatment (348 µIU/mL) 30 min after feed provision compared with the prescribed treatment (190 µIU/mL). Video analysis of spatial preference within HC suggested pigs in the prescribed treatment spent more (P < 0.05) time in quadrant 4 during wk 1 (5.43% of time recorded) compared with the ad libitum treatment (3.82% of time recorded), likely due to quadrant 4 housing the feed bowl. However, all other time points had no effect on spatial preference. Overall, the type of feeding style altered growth performance and insulin concentrations within young pigs and may impact the spatial preference of pigs within their home-cage environment.

Thiazolidinedione enhances the efficacy of anti-PD-1 monoclonal antibody in murine melanoma.

Several clinical studies observed a surprising beneficial effect of obesity on enhancing immunotherapy responsiveness in patients with melanoma, highlighting an as-yet insufficiently understood relationship between metabolism and immunogenicity. Here, we demonstrate that the thiazolidinedione (TZD) rosiglitazone, a drug commonly used to treat diabetes by sequestering fatty acids in metabolically inert subcutaneous adipose tissue, improved sensitivity to anti-programmed cell death protein 1 (PD-1) treatment in YUMMER1.7 tumor-bearing mice, an initially immunotherapy-sensitive murine melanoma model. We observed a transition from high to intermediate PD-1 expression in tumor-infiltrating CD8+ T cells. Moreover, TZD inhibited PD-1 expression in mouse and human T cells treated in vitro. In addition to its direct impact on immune cells, TZD also decreased circulating insulin concentrations, while insulin induced T cell exhaustion in culture. In TZD-treated mice, we observed higher fatty acid concentrations in the tumor microenvironment, with fatty acids protecting against exhaustion in culture. Together, these data are consistent with an indirect mechanism of TZD inhibiting T cell exhaustion. Finally, we analyzed imaging data from patients with melanoma before and after anti-PD-1 treatment, confirming the beneficial effect of increased subcutaneous fat on anti-PD-1 responsiveness in patients. We also found that the expression of peroxisome proliferator-activated receptor gamma (PPARγ), the canonical activator of lipid uptake and adipogenesis activated by TZD, correlated with overall survival time. Taken together, these data identify a new adjuvant to enhance immunotherapy efficacy in YUMMER1.7 melanoma mice, and discover a new metabolism-based prognostic marker in human melanoma.NEW & NOTEWORTHY Zhang et al. demonstrate that the diabetes drug rosiglitazone improves the efficacy of immunotherapy in mouse melanoma. This effect is both direct and indirect: TZD directly reduces PD-1 expression in CD8+ T cells (i.e., reduces exhaustion), and indirectly reduces exhaustion by lowering insulin levels and increasing local fat. Finally, they demonstrate that hallmarks of TZD action (such as PPARγ expression and subcutaneous fat content) correlate with improved immunotherapy efficacy in humans with melanoma.

Pregnancy glucagon-like peptide 1 predicts insulin but not glucose concentrations

AimsIncretin hormones glucagon-like peptide 1 (GLP-1) and gastric inhibitory peptide (GIP) cause increased insulin secretion in non-pregnant adults, but their role in pregnancy, where there are additional metabolically-active hormones from the placenta, is less clear. The aim of the present study was to assess if fasting and post-load incretin concentrations were predictive of pregnancy insulin and glucose concentrations.MethodsPregnant women (n = 394) with one or more risk factors for gestational diabetes were recruited at 28 weeks for a 75 g oral glucose tolerance test (OGTT). Glucose, insulin, GLP-1 and GIP were measured in the fasting state and 120 min after glucose ingestion.ResultsFasting plasma GLP-1 concentrations were associated with plasma insulin (standardised β’ 0.393 (0.289–0.498), p = 1.3 × 10–12; n = 306), but not with glucose concentrations (p = 0.3). The association with insulin was still evident when adjusting for BMI (β’ 0.271 (0.180–0.362), p = 1.1 × 10–8; n = 297). Likewise, at 120 min the OGTT GLP-1 concentrations were associated with plasma insulin concentrations (β’ 0.216 (0.100–0.331), p = 2.7 × 10–4; n = 306) even after adjusting for BMI (β’ 0.178 (0.061–0.294), p = 2.9 × 10–3; n = 296), but not with glucose (p = 0.9). GIP concentrations were not associated with insulin or glucose concentrations at either time point (all p > 0.2). In pregnancy plasma GLP-1, but not GIP, concentrations appear to be predictive of circulating insulin concentrations, independently of associations with BMIs.ConclusionsThese results suggest that the relationship between insulin and incretins is preserved in pregnancy, but that other factors, such as placental hormones or counter-regulatory hormones, may be more important determinants of glycaemia and gestational diabetes aetiology.

Antidiabetic actions of GPR55 agonist Abn-CBD and sitagliptin in obese-diabetic high fat fed mice

GPR55 has been recognized as a novel anti-diabetic target exerting positive effects on beta cell function and mass. This study evaluated the metabolic actions and therapeutic efficacy of GPR55 agonist abnormal cannabidiol (Abn-CBD) administered alone and in combination with sitagliptin in diet-induced obese-diabetic mice.Chronic effects of 21-day oral administration of Abn-CBD (0.1 µmol/kg BW) monotherapy and in combination with sitagliptin (50 mg/kg BW) were assessed in obese-diabetic HFF mice (n = 8). Assessments of plasma glucose, circulating insulin, DPP-IV activity, CRP, amylase, lipids, body weight and food intake were undertaken. Glucose tolerance, insulin sensitivity, DEXA scanning and islet morphology analysis were performed at 21-days.Sitagliptin, Abn-CBD alone and in combination with sitagliptin attenuated plasma glucose by 37–53 % (p < 0.01 – p < 0.001) and enhanced circulating insulin concentrations by 23–31 % (p < 0.001). Abn-CBD alone and with sitagliptin reduced bodyweight by 9–10 % (p < 0.05). After 21-days, Abn-CBD in combination with sitagliptin (44 %; p < 0.01) improved glucose tolerance, whilst enhancing insulin sensitivity by 79 % (p < 0.01). Abn-CBD increased islet area (86 %; p < 0.05), beta cell mass (p < 0.05) and beta cell proliferation (164 %; p < 0.001), whilst in combination with sitagliptin islet area was decreased (50 %; p < 0.01). Abn-CBD alone, in combination with sitagliptin or sitagliptin alone decreased triglycerides by 34–65 % (p < 0.001) and total cholesterol concentrations by 15–25 % (p < 0.001). In addition, Abn-CBD in combination with sitagliptin reduced fat mass by 19 % (p < 0.05) and reduced CRP concentrations (39 %; p < 0.05).These findings advocate Abn-CBD monotherapy and in combination with sitagliptin as a novel and effective approach for bodyweight control and the treatment of glucose intolerance and dyslipidaemia in type-2-diabetes.

Comparison of production-related responses to hyperinsulinemia and hypoglycemia induced by clamp procedures or heat stress of lactating dairy cattle.

Hyperinsulinemia concurrent with hypoglycemia is one of a myriad of physiological changes typically experienced by lactating dairy cows exposed to heat stress, the consequences of which are not yet well defined or understood. Therefore, the objective of this experiment was to separate the production-related effects of hyperinsulinemia with hypoglycemia from those of a hyperthermic environment. Multiparous lactating Holstein cows (n = 23; 58 ± 4 d in milk, 3.1 ± 0.3 lactations) were housed in temperature-controlled rooms and all were subjected to 4 experimental periods as follows: (1) thermoneutral (TN; temperature-humidity index of 65.1 ± 0.2; d 1-5), (2) TN + hyperinsulinemic-hypoglycemic clamp (HHC; insulin infused at 0.3 µg/kg of BW per h, glucose infused to maintain 90 ± 10% of baseline blood glucose for 96 h; d 6-10), (3) heat stress (HS; temperature-humidity index of 72.5 ± 0.2; d 16-20), and (4) HS + euglycemic clamp (EC; glucose infused to reach 100 ± 10% of TN baseline blood glucose for 96 h; d 21-25). Cows were fed and milked twice daily. Feed refusals were collected once daily for calculation of daily dry matter intake, and milk samples were collected at the beginning and end of each period for component analyses. Circulating insulin concentrations were measured in daily blood samples, whereas glucose concentrations were measured more frequently and variably in association with clamp procedures. Rectal temperatures and respiration rates were greater during HS than TN, as expected, and states of hyperinsulinemia and hypoglycemia were successfully induced by the HHC and high ambient temperatures (HS and EC). Feed intake differed based upon thermal environment as it was similar during TN and HHC periods, and declined for HS and EC. Milk production was not entirely reflective of feed intake as it was greatest during TN, intermediate during HHC, and lowest during HS and EC. All milk components differed with the experimental period, primarily in response to the thermal environment. Interestingly, TN baseline glucose concentrations were highly correlated with the change in glucose from TN to HS, and were related to glycemic status during HS. Furthermore, although few in number, those cows that failed to become hypoglycemic during HS tended to have a greater reduction in milk yield. The work presented here addresses a critical knowledge gap by broadening our understanding of the physiological response to heat stress and the related changes in glycemic state. This broadened understanding is fundamental for the development of novel, innovative management strategies as the dairy industry is compelled to become increasingly efficient in spite of global warming.

Fatty liver indices and their association with glucose metabolism in pregnancy – An observational cohort study

AimsNon-invasive hepatic steatosis indices can be used to assess the risk for metabolic (dysfunction) associated fatty liver disease (MAFLD). This may be helpful to detect metabolic disorders in pregnancy, specifically gestational diabetes (GDM). We aimto examine the association of these indices with parameters of glucose metabolism. Methods109 women underwent a metabolic characterization at 16 weeks of gestation andwere classified according to the fatty-liver index (FLI) andhepatic-steatosis index (HSI) into low (G1), intermediate (G2) and high risk (G3). At 26 weeks, participants received an oral glucose tolerance test (OGTT) to assess insulin action, β-cell function and GDM status. ResultsBoth MAFLD indices wereassociated with impaired insulin sensitivityand compensatory increase of insulin release. G3 groups showedimpaired insulin action. The higher circulating insulin concentrations were not able to compensate for insulin resistance in women with higher MAFLD scores, resulting in an increased risk of GDM(OR: 1.05, 95% CI 1.03 to 1.08, p < 0.001 for FLI). MAFLD scores were associated with fetal overgrowth. ConclusionsMaternal MAFLD represents a high-risk obstetric condition. Hepatic steatosis indices are associated with impaired glucose regulation and may provide a useful tool for early risk assessment for impaired glucose metabolism.

Anticipated Basal Insulin Reduction to Prevent Exercise-Induced Hypoglycemia in Adults and Adolescents Living with Type 1 Diabetes.

Objective: We investigated the effect of two key timings for basal insulin rate reduction on exercise-induced glucose changes and explored the association between circulating insulin concentrations and muscle vasoreactivity. Research Design and Methods: Twenty adults and adolescents performed 60-min exercise sessions (ergocycle) at 60% VO2peak, 240 min after a standardized lunch. In a randomized order, we compared an 80% basal insulin reduction applied 40 min (T-40) or 90 min (T-90) before exercise onset. Near-infrared spectroscopy was used to investigate muscle hemodynamics at vastus lateralis. Glucose and insulin plasma concentrations were measured. Results: Reduction in plasma glucose (PG) level during exercise was attenuated during T-90 versus T-40 strategy (-0.89 ± 1.89 mmol/L vs. -2.17 ± 2.49 mmol/L, respectively; P = 0.09). Linear mixed model analysis showed that PG dropped by an additional 0.01 mM per minute in T-40 versus T-90 (time × strategy interaction, P < 0.05). The absolute number of hypoglycemic events was not different between the two strategies, but they occurred later with T-90. Free insulin tends to decrease more during the pre-exercise period in the T-90 strategy (P = 0.08). Although local muscle vasodilatation (ΔTHb) was comparable between the two strategies, we found that PG dropped more in cases of higher exercise-induced skeletal muscle vasodilatation (ΔTHb × time interaction P < 0.005, e: -0.0086 mM/min and additional mM of ΔTHb). Conclusion: T-90 timing reduced exercise-induced drop in PG and delayed the occurrence of hypoglycemic episodes compared with T-40 timing without a significant reduction in the number of events requiring treatment. Trial registration: ClinicalTrials.gov identifier: NCT03349489.

Insulin and the insulin receptor collaborate to promote human gastric cancer

BackgroundGastric adenocarcinoma is common and consequent mortality high. Presentation and mortality are increased in obese individuals, many of whom have elevated circulating insulin concentrations. High plasma insulin concentrations may promote, and increase mortality from, gastric adenocarcinoma. Tumour promotion activities of insulin and its receptor are untested in gastric cancer cells.MethodsTumour gene amplification and expression were computed from sequencing and microarray data. Associations with patient survival were assessed. Insulin-dependent signal transduction, growth, apoptosis and anoikis were analysed in metastatic cells from gastric adenocarcinoma patients and in cell lines. Receptor involvement was tested by pharmacological inhibition and genetic knockdown. RNA was analysed by RT-PCR and proteins by western transfer and immunofluorescence.ResultsINSR expression was higher in tumour than in normal gastric tissue. High tumour expression was associated with worse patient survival. Insulin receptor was detected readily in metastatic gastric adenocarcinoma cells and cell lines. Isoforms B and A were expressed. Pharmacological inhibition prevented cell growth and division, and induced caspase-dependent cell death. Rare tumour INS expression indicated tumours would be responsive to pancreatic or therapeutic insulins. Insulin stimulated gastric adenocarcinoma cell PI3-kinase/Akt signal transduction, proliferation, and survival. Insulin receptor knockdown inhibited proliferation and induced programmed cell death. Type I IGF receptor knockdown did not induce cell death.ConclusionsThe insulin and IGF signal transduction pathway is dominant in gastric adenocarcinoma. Gastric adenocarcinoma cell survival depends upon insulin receptor. That insulin has direct cancer-promoting effects on tumour cells has implications for clinical management of obese and diabetic cancer patients.

Factors Influencing Insulin Absorption Around Exercise in Type 1 Diabetes.

International charities and health care organizations advocate regular physical activity for health benefit in people with type 1 diabetes. Clinical expert and international diabetes organizations’ position statements support the management of good glycemia during acute physical exercise by adjusting exogenous insulin and/or carbohydrate intake. Yet research has detailed, and patients frequently report, variable blood glucose responses following both the same physical exercise session and insulin to carbohydrate alteration. One important source of this variability is insulin delivery to the circulation. With modern insulin analogs, it is important to understand how different insulins, their delivery methods, and inherent physiological factors, influence the reproducibility of insulin absorption from the injection site into circulation. Furthermore, contrary to the adaptive pancreatic response to exercise in the person without diabetes, the physiological and metabolic shifts with exercise may increase circulating insulin concentrations that may contribute to exercise-related hyperinsulinemia and consequent hypoglycemia. Thus, a furthered understanding of factors underpinning insulin delivery may offer more confidence for healthcare professionals and patients when looking to improve management of glycemia around exercise.

Correlating Circulating Vitamin D3 with Aspects of the Metabolic Syndrome and Nonalcoholic Fatty Liver Disease in Healthy Female Volunteers

Background: Significant inverse correlations between circulating vitamin D3 and the presence and strength of common clinical entities influenced by insulin resistance (IR) have been reported. Among these entities are common maladies such as the metabolic syndrome (MS) and nonalcoholic fatty liver disease (NAFLD). Since hypovitaminosis D3 is considered a common worldwide health disturbance, the consequences emanating from such relationships once soundly established might reasonably be ameliorated by vitamin replacement. Accordingly, a need exists for definitive confirmatory support for the existence of these linkages particularly in ordinary, relatively healthy individuals.Methodology: Many aspects of MS and NAFLD were examined in healthy females via linear regression analyses to determine significant correlations mainly using vitamin D3 and fasting blood glucose (FBG), the latter a surrogate for IR, as independent variables.Results: A descending linear regression between vitamin D3 and FBG did not reach full statistical significance, but a negative correlation of vitamin D3 with HbA1C was statistically significant and that with circulating insulin concentrations showed a downward statistical trend. These findings are consistent with previous ones by others suggesting an ameliorating effect of vitamin D3 on IR. Body weight, body mass index (BMI), and body fat correlated statistically significantly with vitamin D3 levels, as did systolic blood pressure. Again, these correlations were negative instead of positive unlike the case when FBG was the independent variable. The significant negative correlation of ALT with vitamin D3 was also consistent with previous reports that higher circulating vitamin D3 favorably influences the extent and intensity of NAFLD.Conclusions: Employing FBG as a surrogate for IR and ALT for status of NAFLD, linear correlations reasonably suggest that increasing circulating vitamin D3 can favorably influence the initial development of and/or strength of risk factors for MS including NAFLD in relatively fit females.

Peripheral serotonin regulates glucose and insulin metabolism in Holstein dairy calves

Peripheral serotonin regulates energy metabolism in several mammalian species, however, the potential contribution of serotonergic mechanisms as metabolic and endocrine regulators in growing dairy calves remain unexplored. Objectives were to characterize the role of serotonin in glucose and insulin metabolism in dairy calves with increased serotonin bioavailability. Milk replacer was supplemented with saline, 5-hydroxytryptophan (90 mg/d), or fluoxetine (40 mg/d) for 10-d (n = 8/treatment). Blood was collected daily during supplementation and on days 2, 7, and 14 during withdrawal. Calves were euthanized after 10-d supplementation or 14-d withdrawal periods to harvest liver and pancreas tissue. 5-hydroxytryptophan increased circulating insulin concentrations during the supplementation period, whereas both treatments increased circulating glucose concentration during the withdrawal period. The liver and pancreas of preweaned calves express serotonin factors (ie, TPH1, SERT, and cell surface receptors), indicating their ability to synthesize, uptake, and respond to serotonin. Supplementation of 5-hydroxytryptophan increased hepatic and pancreatic serotonin concentrations. After the withdrawal period, fluoxetine cleared from the pancreas but not liver tissue. Supplementation of 5-hydroxytryptophan upregulated hepatic mRNA expression of serotonin receptors (ie, 5-HTR1B, -1D, -2A, and -2B), and downregulated pancreatic 5-HTR1F mRNA and insulin-related proteins (ie, Akt and pAkt). Fluoxetine-supplemented calves had fewer pancreatic islets per microscopic field with reduced insulin intensity, whereas 5-hydroxytryptophan supplemented calves had increased islet number and area with greater insulin and serotonin and less glucagon intensities. After the 14-d withdrawal of 5-hydroxytryptophan, hepatic mRNA expression of glycolytic and gluconeogenic enzymes were simultaneously downregulated. Improving serotonin bioavailability could serve as a potent regulator of endocrine and metabolic processes in dairy calves.

OR26-07 Mild Physiologic Hyperglycemia Does Not Affect Glucose Mediated but Impairs Insulin-Mediated Suppression of Plasma Glucagon in Healthy Normal Glucose Tolerant Subjects

Plasma glucagon levels are regulated by plasma glucose concentrations as well as intra-islet and circulating insulin concentrations. Hyperglycemia adversely affects skeletal muscle and hepatic insulin sensitivity (glucotoxicity). However, the effect of physiologic hyperglycemia on glucose-mediated and insulin-mediated suppression of glucagon is not known. The aim of the present study was to evaluate effect of chronic (48 or 72 hours) physiologic increase (+45 mg/dl) in plasma glucose concentration on the suppression of plasma glucagon concentration in healthy NGT individuals: 12 without family history of T2DM (FH-) (9M/3F, age = 50± 4 yrs, BMI = 27 ± 1 kg/m2) and 8 with FH of T2DM (FH+) (4M/4F, age = 48±2, BMI = 26±1 kg/m2). Subjects received an OGTT and 2-step hyperglycemic (+125 and +300 mg/dl) clamp (duration of each step = 80 minutes) before and after 72 hour glucose infusion. On another occasion subjects participated in a 3-step hyperinsulinemic (10, 20, 40 mU/m2·min) euglycemic clamp before and after a 48 hour glucose infusion. Plasma insulin and C-peptide concentrations were obtained every 2-5 minutes during each hyperglycemic clamp step and plasma glucagon concentrations were measured every 10 minutes. The ratio of insulin/glucagon was measured and used as an index of insulin-medicated suppression of plasma glucagon. FPG concentration increased from 97±4 to 140±4 mg/dl during the 72 hour glucose infusion. Following chronic glucose infusion, plasma insulin levels were significantly higher during the basal state and during each hyperglycemic clamp step (by 59% and 78%). There was no difference in plasma glucagon levels following chronic glucose infusion and the degree of suppression of glucagon during 2-step hyperglycemic (+125 and +300 mg/dl) were similar. However, the plasma insulin/glucagon ratio was significantly higher during the fasting state (by 76%) and during the first (by 128%) and second (by 178%) hyperglycemic clamp steps. Similarly during the three step euglycemic clamp (10, 20, 40 mU/m2·min) studies following 48 hr glucose infusion, despite similar plasma glucose concentrations during each clamp step, plasma insulin and glucagon concentrations were higher following chronic glucose infusion. These results demonstrate that sustained physiologic hyperglycemia for 48 hrs or 72 hours (i.e. glucotoxicity) does not affect the glucose mediated suppression of glucagon, but impairs insulin-mediated suppression of glucagon, and could contribute to fasting and post-prandial hyperglycemia in T2DM patients.

Dietary supplementation of artificial sweetener and capsicum oleoresin as a strategy to mitigate the negative consequences of heat stress on pig performance.

Pigs exposed to elevated ambient temperatures exhibit reduced daily gain, alterations in muscle and fat deposition, and decreased health. Negative aspects of gastrointestinal (GI) function, integrity, and permeability also occur. High-intensity sweeteners can ameliorate the negative effects of heat stress (HS) by increasing GI glucagon-like peptide-2 production while capsicum oleoresin has been shown to reduce inflammatory response. The effects of an artificial high-intensity sweetener and capsicum oleoresin (CAPS-SUC; TakTik X-Hit, Pancosma, Switzerland) on growth performance of pigs were examined. Forty-eight pigs (12 wk of age, 43.2 ± 4.3 kg) were assigned to six treatments: thermoneutral conditions (21 ± 1.1 °C; 40% to 70% relative humidity) fed ad libitum with (TN+) or without supplement (TN-), heat stress (35 ± 1 °C; 20% to 40% relative humidity) fed ad libitum with (HS+) or without supplement (HS-), and thermoneutral conditions pair-fed to HS intake with (PFTN+) or without supplement (PFTN-). Supplementation (0.1 g/kg feed) began 2 d prior to the 3-d environmental treatment period. Body weights (BWs) and blood samples were collected on days -1 and 3. Rectal temperature (RT) and respiration rate (RR) were measured thrice daily and the feed intake (FI) was recorded daily. Intestinal sections were collected for histology. Pigs in HS conditions exhibited increased RT (~1.2 °C) and RR (~2.7-fold) compared with TN and PFTN groups (P < 0.01). HS+ animals had increased RR when compared with HS- animals (P < 0.02). Heat stress decreased FI compared with TN. HS and PFTN decreased (P < 0.05) average daily gain compared with TN. Supplement did not alter the BW gain. HS and PFTN decreased (P < 0.05) Gain:Feed compared with TN during environmental treatment. Supplementation with CAPS-SUC increased Gain:Feed by 0.12 (P < 0.05). Circulating glucose concentrations tended to decrease in CAPS-SUC vs. non-supplemented HS and PFTN animals (P ≤ 0.1). Circulating insulin concentrations as well as monocyte count increased in HS compared with PFTN (P < 0.04) but did not differ from TN and likely linked to altered FI. CAPS-SUC increased basophil count (P < 0.02), irrespective of environment. Ileal villus height tended to decrease during HS and PFTN compared with TN (P < 0.08), indicating an effect of intake. Overall, CAPS-SUC supplementation increased pig feed efficiency and may improve immune response.

Cancer Attenuates Nutrient Activation of Skeletal Muscle mTORC1 in Female Mice

Cancer‐induced metabolic disruptions can alter tissue specific energy demands and has the potential to alter muscle responses to feeding. Mechanistic target of rapamycin complex 1 (mTORC1) signaling axis is activated by nutrient stimuli, and cancer cachexia can suppress basal muscle mTORC1 signaling in mice. However, gaps still remain in our understanding of how the cancer environment effects skeletal muscle nutrient regulation of mTORC1 signaling.PurposeWe examined the effect of feeding on skeletal muscle mTORC1 signaling in female tumor bearing mice.MethodsFemale C57BL/6 (B6) and ApcMin/+ (MIN) mice were fasted for 12‐hrs during the light cycle. Following the 12‐hr fast, mice were given access to a food pellet for 1‐hr (B6 FED:N=7, MIN FED:N=8) or fasted for another hour (B6 FAST:N=6, MIN FAST:N=7). Circulating blood glucose, and plasma IL‐6 and insulin were taken prior to sacrifice. Gastrocnemius muscle was homogenized for protein analysis. Statistical significance was set at p£0.05.ResultsThe MIN FED and MIN FAST groups were not different in percent body weight change, polyp number, plasma IL‐6, and hindlimb muscle mass. 1‐hour food intake was not different between B6 FED and MIN FED mice. Both MIN FED and B6 FED increased stomach mass, blood glucose, and circulating insulin levels. Compared to FAST mice, FED mice increased p70S6K and rpS6 phosphorylation, and was positively associated to insulin in both B6 and MIN mice. 4E‐BP1 phosphorylation was increased in the B6 FED compared to B6 FAST, but this response was blunted in the MIN FED. Additionally, circulating insulin concentration was associated to 4E‐BP1 phosphorylation in the B6 FED, but not in the MIN FED.ConclusionThe cancer environment can suppress the nutrient‐induced phosphorylation of skeletal muscle 4E‐BP1. Future studies are warranted to determine if the combination of exercise or muscle contraction can improve skeletal muscle mTORC1’s response to nutrients in the female cancer environmentAcknowledgementsNCI R01‐CA121249

Insulin does not stimulate β-alanine transport into human skeletal muscle.

To test whether high circulating insulin concentrations influence the transport of β-alanine into skeletal muscle at either saturating or subsaturating β-alanine concentrations, we conducted two experiments whereby β-alanine and insulin concentrations were controlled. In experiment 1, 12 men received supraphysiological amounts of β-alanine intravenously (0.11 g·kg-1·min-1 for 150 min), with or without insulin infusion. β-Alanine and carnosine were measured in muscle before and 30 min after infusion. Blood samples were taken throughout the infusion protocol for plasma insulin and β-alanine analyses. β-Alanine content in 24-h urine was assessed. In experiment 2, six men ingested typical doses of β-alanine (10 mg/kg) before insulin infusion or no infusion. β-Alanine was assessed in muscle before and 120 min following ingestion. In experiment 1, no differences between conditions were shown for plasma β-alanine, muscle β-alanine, muscle carnosine and urinary β-alanine concentrations (all P > 0.05). In experiment 2, no differences between conditions were shown for plasma β-alanine or muscle β-alanine concentrations (all P > 0.05). Hyperinsulinemia did not increase β-alanine uptake by skeletal muscle cells, neither when substrate concentrations exceed the Vmax of β-alanine transporter TauT nor when it was below saturation. These results suggest that increasing insulin concentration is not necessary to maximize β-alanine transport into muscle following β-alanine intake.

Association of Insulin Secretion Level on Lipid Fractions and Risk of Arterial Hypertension

Background: The existing literature reports results on the association of lipid parameters with the level of insulin secretion and the risk of arterial hypertension. Objective: This study evaluated the role of the insulin dosage and lipid fractions in the risk of arterial hypertension in type 2 diabetic patients in Western Algeria. Methods: This was a cross-sectional observational study involving 101 subjects with type 2 diabetes mellitus. The data collected was about the biodemographic profile of the participants. We performed multiple regressions to test the effect of insulin concentration on the parameters studied. Results: The multiple regression analytical study showed that HOMA-IR, BMI and waist circumference were predictors for the insulinemia response variable (P&lt;0.05). It should be noted that in insulinopenia, insulin secretion is positively and significantly correlated with non-HDL-C (P=0.037), and it is also significantly and positively correlated with LDL-C (P=0.042). Multiple regression also shows that SBP and DBP are significantly and positively related to insulin resistance. Our data suggest a possible direct relationship between fasting insulin and blood pressure. Conclusion: Monitoring of circulating insulin concentrations is critically important in a population of type 2 diabetics.

Glucose Metabolism and Cecal Microbiome Populations Are Improved and Hepatic Biochemical Levels Altered with Consumption of Grape Powder by High-fat Fed C57BL/6 J Mice (P06-024-19)

ObjectivesGrapes are nutrient-dense, particularly in polyphenolic compounds. Previous research demonstrates benefits of whole grape and grape skin, seed, and polyphenol intake on glucose homeostasis along with other health benefits. We tested the hypothesis that intake of 4 servings per day of table grape would remediate metabolic complications in C57BL/6 J (C57) male mice fed a high-fat diet with added cholesterol and fructose diet modeling an obesogenic and diabetogenic western-style diet. MethodsGroups of mice (n = 12) were provided either low-fat plus placebo diet (LF, 10% kcal fat), high-fat plus placebo (HF, 45% kcal fat), or HF plus grape powder (HF + G), for 8 weeks. Grape powder was provided at ∼10% of total energy of diet. C57 mice were provided experimental diets ad libitum. Body weights, food intake, and glucose tolerance were determined. Postmortem, inflammatory markers, cecal microbiome, and the relative concentrations of hepatic metabolites were determined. ResultsFasting blood glucose was reduced in the HF + G group compared to HF-fed mice. The glucose tolerance test demonstrated that the Area Under the Curve (AUC) was also reduced. Further, a significant decrease in circulating levels of insulin were observed with HF + G supplementation. The cecal microbiome from HF + G fed mice overlapped with both the HF and LF controls, but also had characteristic shifts that were unique to grape powder consumption. Metabolomic analysis indicated grape consumption impacted inflammation and β-oxidation biomarkers indicating some remediation of hepatic pathologies associated with HF food consumption. The most significantly different hepatic metabolites included grape-derived S-methymethionine and trigonelline, while other murine hepatic metabolites significantly regulated by diet included myo-inositol and 15-HETE. ConclusionsTable grape supplementation with a HF western-style diet significantly improved fasting blood glucose, circulating insulin concentrations, and HOMA-IR in C576J/Bl male mice. demonstrating an anti-diabetic effect of grape powder. At modest level of supplementation equivalent to 4 servings/day, grape powder also improved microbiome composition and changed relative levels of specific hepatic metabolites. Up-regulation of 15-HETE by diet suggests grape powder consumption may enhance PPARγ-directed gene expression, consistent with increases in glucose sensitivity observed in this study. Funding SourcesCalifornia Table Grape Commission.

Interplay of Glycemic Index, Glycemic Load, and Dietary Antioxidant Capacity with Insulin Resistance in Subjects with a Cardiometabolic Risk Profile.

Background: Dietary total antioxidant capacity (TAC), glycemic index (GI), and glycemic load (GL) are accepted indicators of diet quality, which have an effect on diet–disease relationships. The aim of this study was to evaluate potential associations of dietary TAC, GI, and GL with variables related to nutritive status and insulin resistance (IR) risk in cardiometabolic subjects. Methods: A total of 112 overweight or obese adults (age: 50.8 ± 9 years old) were included in the trial. Dietary intake was assessed by a validated 137-item food frequency questionnaire (FFQ), which was also used to calculate the dietary TAC, GI, and GL. Anthropometrics, blood pressure, body composition by dual-energy X-ray absorptiometry (DXA), glycemic and lipid profiles, C-reactive protein (CRP), as well as fatty liver quantification by magnetic resonance imaging (MRI) were assessed. Results: Subjects with higher values of TAC had significantly lower circulating insulin concentration and homeostatic model assessment of insulin resistance (HOMA-IR). Participants with higher values of HOMA-IR showed significantly higher GI and GL. Correlation analyses showed relevant inverse associations of GI and GL with TAC. A regression model evidenced a relationship of HOMA-IR with TAC, GI, and GL. Conclusion: This data reinforces the concept that dietary TAC, GI, and GL are potential markers of diet quality, which have an impact on the susceptible population with a cardiometabolic risk profile.

Insulinotropic activity of the host-defense peptide frenatin 2D: Conformational, structure-function and mechanistic studies

Of four naturally occurring frenatin peptides tested, frenatin 2D (DLLGTLGNLPLPFI.NH2) from Discoglossus sardus was the most potent and effective in producing concentration-dependent stimulation of insulin release from BRIN-BD11 rat clonal β-cells without displaying cytotoxicity. The peptide also stimulated insulin release from 1.1B4 human-derived clonal β-cells and isolated mouse islets and improved glucose tolerance concomitant with increased circulating insulin concentrations in mice following intraperitoneal administration. The insulinotropic activity of frenatin 2D was not associated with membrane depolarization or an increase in intracellular [Ca2+] but incubation of the peptide (1 μM) with BRIN-BD11 cells produced a modest, but significant (P < 0.05), increase in cAMP production. Stimulation of insulin release was abolished in protein kinase A-downregulated cells but maintained in protein kinase C-downregulated cells. Circular dichroism studies showed that, in the presence of dodecylphosphocholine micelles, frenatin 2D exhibited a helical content of 35% and a turn content of 28%. Substitution of the Thr5, Asn8, Pro10, and Ile14 residues in frenatin-2D by Trp and interchange of Pro12 and Phe13 led to loss of insulinotropic activity but the [D1W] and [G7W] analogues were as potent and effective as the native peptide. Frenatin 2D (1 μM) also stimulated proliferation of BRIN-BD11 cells and provided significant protection of the cells against cytokine-induced apoptosis. It is concluded that the insulinotropic activity of frenatin 2D is mediated predominantly, if not exclusively, by the KATP channel-independent pathway.

Increase in hepatic and decrease in peripheral insulin clearance characterize abnormal temporal patterns of serum insulin in diabetic subjects

Insulin plays a central role in glucose homeostasis, and impairment of insulin action causes glucose intolerance and leads to type 2 diabetes mellitus (T2DM). A decrease in the transient peak and sustained increase of circulating insulin following an infusion of glucose accompany T2DM pathogenesis. However, the mechanism underlying this abnormal temporal pattern of circulating insulin concentration remains unknown. Here we show that changes in opposite direction of hepatic and peripheral insulin clearance characterize this abnormal temporal pattern of circulating insulin concentration observed in T2DM. We developed a mathematical model using a hyperglycemic and hyperinsulinemic-euglycemic clamp in 111 subjects, including healthy normoglycemic and diabetic subjects. The hepatic and peripheral insulin clearance significantly increase and decrease, respectively, from healthy to borderline type and T2DM. The increased hepatic insulin clearance reduces the amplitude of circulating insulin concentration, whereas the decreased peripheral insulin clearance changes the temporal patterns of circulating insulin concentration from transient to sustained. These results provide further insight into the pathogenesis of T2DM, and thus may contribute to develop better treatment of this condition.