Clearance Rate Of Glucose Research Articles

Identification and Characterization of a Novel Insulin-like Receptor (LvRTK2) Involved in Regulating Growth and Glucose Metabolism of the Pacific White Shrimp Litopenaeus vannamei.

The insulin receptor (IR) plays a crucial role in the growth and metabolism of animals. However, there are still many questions regarding the IR in crustaceans, particularly their role in shrimp growth and glucose metabolism. In this study, we identified a novel insulin-like receptor gene in Litopenaeus vannamei and cloned its full length of 6439 bp. This gene exhibited a highly conserved sequence and structural characteristics. Phylogenetic analysis confirmed it as an unreported RTK2-type IR, namely, LvRTK2. Expression pattern analysis showed that LvRTK2 is primarily expressed in female reproductive and digestive organs. Through a series of in vivo and in vitro experiments, including glucose treatment, exogenous insulin treatment, and starvation treatment, LvRTK2 was confirmed to be involved in the endogenous glucose metabolic pathway of shrimp under different glucose variations. Moreover, long-term and short-term interference experiments with LvRTK2 revealed that the interference significantly reduced the shrimp growth rate and serum glucose clearance rate. Further studies indicated that LvRTK2 may regulate shrimp growth by modulating the downstream PI3K/AKT signaling pathway and a series of glucose metabolism events, such as glycolysis, gluconeogenesis, glycogen synthesis, and glycogenolysis. This report on the characteristics and functions of LvRTK2 confirms the important role of RTK2-type IRs in regulating shrimp growth and glucose metabolism.

Fetal sex effects on maternal health can now be tested via randomization: A first-in-class illustration in cows on glucoregulatory outcomes

BackgroundThe maternal-offspring relationship, such as whether fetal sex influences maternal health, is essential to explore to advance prenatal and maternal health. While associations exist between fetal sex and maternal health outcomes, it is unclear whether these reflect a causal relationship. ObjectiveTo demonstrate that fetal sex can be randomly assigned to test the causal effect of fetal sex on maternal outcomes. MethodsHolstein dairy cows were stratified and randomized using sealed opaque envelopes to be artificially inseminated with either X- or Y-sorted bull semen until 40 cows became pregnant. Monthly body weight measurements were recorded, and an intravenous glucose tolerance test was performed 30 days before the expected calving day. The primary outcome was insulin area under the curve (AUC), and secondary outcomes were clearance rate, half-life, and AUC for glucose, insulin, and non-esterified fatty acid concentrations. An intention-to-treat (ITT) approach using multiple imputation was employed for primary analysis, and an as-treated (AT) approach was used for secondary analysis. ResultsWe demonstrated that we could successfully randomize the assignment of fetal sex to dams and test for causal effects of fetal sex on glucoregulatory outcomes using dairy cows as a model. Insulin AUC was not statistically different between groups (ITT p = 0.857, AT p = 0.874), and other outcomes were also not statistically different (p > 0.05). ConclusionWe demonstrated that causal effects of fetal sex on maternal outcomes can be causally tested in dairy cows. Our study did not provide statistical evidence to support an effect of fetal sex on maternal glucose-related outcomes.

Heat stress affects mammary metabolism by influencing the plasma flow to the glands

BackgroundEnvironmental heat stress (HS) can have detrimental effects on milk production by compromising the mammary function. Mammary plasma flow (MPF) plays a crucial role in nutrient supply and uptake in the mammary gland. In this experiment, we investigated the physiological and metabolic changes in high-yielding cows exposed to different degrees of HS: no HS with thermal-humidity index (THI) below 68 (No-HS), mild HS (Mild-HS, 68 ≤ THI ≤ 79), and moderate HS (Mod-HS, 79 < THI ≤ 88) in their natural environment. Our study focused on the changes in blood oxygen supply and mammary glucose uptake and utilization.ResultsCompared with No-HS, the MPF of dairy cows was greater (P < 0.01) under Mild-HS, but was lower (P < 0.01) in cows under Mod-HS. Oxygen supply and consumption exhibited similar changes to the MPF under different HS, with no difference in ratio of oxygen consumption to supply (P = 0.46). The mammary arterio-vein differences in glucose concentration were lower (P < 0.05) under Mild- and Mod-HS than under no HS. Glucose supply and flow were significantly increased (P < 0.01) under Mild-HS but significantly decreased (P < 0.01) under Mod-HS compared to No-HS. Glucose uptake (P < 0.01) and clearance rates (P < 0.01) were significantly reduced under Mod-HS compared to those under No-HS and Mild-HS. Under Mild-HS, there was a significant decrease (P < 0.01) in the ratio of lactose yield to mammary glucose supply compared to that under No-HS and Mod-HS, with no difference (P = 0.53) in the ratio of lactose yield to uptaken glucose among different HS situations.ConclusionsDegrees of HS exert different influences on mammary metabolism, mainly by altering MPF in dairy cows. The output from this study may help us to develop strategies to mitigate the impact of different degrees of HS on milk production.

CTRP9 Promotes Brown Adipose Tissue Lipolysis in Mice Fed a High-Fat Diet.

This study aimed to elucidate the molecular mechanism through which C1q/tumor necrosis factor (TNF)-related protein 9 (CTRP9) acts in the formation and differentiation of brown adipose tissue (BAT). Adenovirus particles encoding CTRP9 and green fluorescent protein were inoculated into the scapula of C57BL/6J mice and fed a high-fat diet for 8 weeks; the body weight, lipid droplet morphology, glucose tolerance, insulin tolerance, and protein expression levels were analyzed. In addition, CTRP9 adenovirus was transfected into brown preadipocytes, and differentiation was induced to identify the effect of CTRP9 overexpression on adipocyte differentiation. CTRP9 overexpression significantly increased the weight gain of mice. Additionally, the CTRP9 overexpression group exhibited significantly increased adipose tissue weight and glucose clearance rates and decreased insulin sensitivity and serum triglyceride levels compared to the control group. Furthermore, CTRP9 overexpression significantly upregulated the adipose triglyceride lipase (ATGL) and perilipin 1 protein expression levels in BAT. The cell experiment results confirmed that CTRP9 overexpression significantly inhibited the adipogenesis of brown adipocytes as evidenced by the downregulation of uncoupling protein 1, beta-3 adrenergic receptor, ATGL, and hormone-sensitive lipase mRNA levels and the significant suppression of uncoupling protein 1, ATGL, and perilipin 1 protein levels in brown adipocytes. The finding of this study demonstrated that CTRP9 promotes lipolysis by upregulating ATGL expression in vivo and inhibits the differentiation of brown preadipocytes in vitro.

Association of postabsorptive glucose and acetate metabolism with feed intake, growth, and efficiency in finishing beef heifers

The objective of this experiment was to determine whether acetate and glucose metabolism and insulin response to glucose are associated with the growth, feed intake, and feed efficiency of finishing heifers. Charolais heifers ( n = 18; initial body weight = 415.7 ± 45.17 kg) were acclimated to restraint with a halter and fed a finishing diet ad libitum using an Insentec feeding system. Following a 12 h fast, a jugular catheter was inserted, and an acetate clearance test was performed followed by a glucose clearance test. Four days after the metabolic tests, heifers began an 84-day DMI and ADG test period. Heifers gained 1.69 ± 0.03 kg/day and consumed 10.4 ± 0.19 kg/day. Acetate and glucose clearance rates were not associated with any production trait ( P ≥ 0.40). Insulin time to peak concentration after the glucose challenge was associated ( r = 0.69; P = 0.003) with G:F, but not peak concentration ( P = 0.45). The increased time to insulin peak could indicate that efficient heifers have pancreatic β-cell dysfunction, which is a contributor to insulin resistance. These data indicate that insulin resistance early in the finishing period could be related to improved feed efficiency in finishing heifers.

Hypoxia impairs blood glucose homeostasis in naked mole-rat adult subordinates but not queens.

Naked mole-rats (NMRs) are among the most hypoxia-tolerant mammals and metabolize only carbohydrates in hypoxia. Glucose is the primary building block of dietary carbohydrates, but how blood glucose is regulated during hypoxia has not been explored in NMRs. We hypothesized that NMRs mobilize glucose stores to support anaerobic energy metabolism in hypoxia. To test this, we treated newborn, juvenile and adult (subordinate and queen) NMRs in normoxia (21% O2) or hypoxia (7, 5 or 3% O2), while measuring metabolic rate, body temperature and blood [glucose]. We also challenged animals with glucose, insulin or insulin-like growth factor-1 (IGF-1) injections and measured the rate of glucose clearance in normoxia and hypoxia. We found that: (1) blood [glucose] increases in moderate hypoxia in queens and pups, but only in severe hypoxia in adult subordinates and juveniles; (2) glucose tolerance is similar between developmental stages in normoxia, but glucose clearance times are 2- to 3-fold longer in juveniles and subordinates than in queens or pups in hypoxia; and (3) reoxygenation accelerates glucose clearance in hypoxic subordinate adults. Mechanistically, (4) insulin and IGF-1 reduce blood [glucose] in subordinates in both normoxia but only IGF-1 impacts blood [glucose] in hypoxic queens. Our results indicate that insulin signaling is impaired by hypoxia in NMRs, but that queens utilize IGF-1 to overcome this limitation and effectively regulate blood glucose in hypoxia. This suggests that sexual maturation impacts blood glucose handling in hypoxic NMR queens, which may allow queens to spend longer periods of time in hypoxic nest chambers.

β-Cell Function, Incretin Effect, and Glucose Kinetics in Response to a Mixed Meal in Patients With Type 2 Diabetes Treated With Dapagliflozin Plus Saxagliptin.

To explore the complementary effects of a combination of dipeptidyl peptidase 4 and sodium-glucose cotransporter 2 inhibitors added to metformin on hormonal and metabolic responses to meal ingestion. Forty-five patients (age 58 ± 8 years; HbA1c 58 ± 6 mmol/mol; BMI 30.7 ± 3.2 kg/m2) with type 2 diabetes uncontrolled with metformin were evaluated at baseline and 3 and 28 days after 5 mg saxagliptin (SAXA), 10 mg dapagliflozin (DAPA), or 5 mg saxagliptin plus 10 mg dapagliflozin (SAXA+DAPA) using a mixed-meal tolerance test (MMTT) spiked with dual-tracer glucose to assess glucose metabolism, insulin secretion, and sensitivity. At day 3, fasting and mean MMTT glucose levels were lower with SAXA+DAPA (-31.1 ± 1.6 and -91.5 ± 12.4 mg/dL) than with SAXA (-7.1 ± 2.1 and -53 ± 10.5 mg/dL) or DAPA (-17.0 ± 1.1 and -42.6 ± 10.0 mg/dL, respectively; P < 0.001). Insulin secretion rate (SAXA+DAPA +75%; SAXA +11%; DAPA +3%) and insulin sensitivity (+2.2 ± 1.7, +0.4 ± 0.7, and +0.4 ± 0.4 mg ⋅ kg-1⋅ min-1, respectively) improved with SAXA+DAPA (P < 0.007). Mean glucagon-like peptide 1 (GLP-1) was higher with SAXA+DAPA than with SAXA or DAPA. Fasting glucagon increased with DAPA and SAXA+DAPA but not with SAXA. Fasting endogenous glucose production (EGP) increased with SAXA+DAPA and DAPA. During MMTT, EGP suppression was greater (48%) with SAXA+DAPA (vs. SAXA 44%; P = 0.02 or DAPA 34%; P = 0.2). Metabolic clearance rate of glucose (MCRglu) increased more with SAXA+DAPA. At week 4, insulin secretion rate, β-cell glucose sensitivity, and insulin sensitivity had further increased in the SAXA+DAPA group (P = 0.02), with no additional changes in GLP-1, glucagon, fasting or MMTT EGP, or MCRglu. SAXA+DAPA provided superior glycemic control compared with DAPA or SAXA, with improved β-cell function, insulin sensitivity, GLP-1 availability, and glucose clearance.

Abstract P429: Coffee Intake is Associated With Enhanced Insulin Sensitivity, Lower Post-Load Glucose Responses, and Lower Truncal Adiposity

Higher coffee consumption has been associated with lower type 2 diabetes (T2D) risk, but the underlying mechanisms remain unclear. We tested the hypothesis that coffee intake is associated with improved glycemia insulin sensitivity, and reduced adiposity. We leveraged data in the VITamin D and OmegA-3 Trial (VITAL), a completed placebo-controlled 5-year trial including 25871 participants. Coffee intake was assessed by a diet questionnaire at baseline and year 2. In the VITAL clinical subcohort (n= 1054), glucose metabolism and insulin resistance were assessed by a 2-hr oral glucose tolerance test, body composition was measured by the dual X-ray absorptiometry, at baseline and year 2. We analyzed the association of coffee intake with glycemic traits and body composition, leveraging repeated assessments using multivariable-adjusted linear mixed models. Secondarily, we tested associations between coffee intake and T2D risk, in 22327 initially T2D-free individuals (482 cases in 5 years of follow-up) using multivariable-adjusted Cox regression. While coffee intake was not associated with fasting glucose or insulin levels, it was significantly associated with lower levels of 2-hr post-load glucose (SD difference per cup increment β = -0.062, P = 0.04) and insulin (β = -0.064, P = 0.02), and a higher metabolic clearance rate of glucose (β= 0.057, P = 0.007) and insulin sensitivity index (β= 0.059, P = 0.02). The associations were consistent for caffeinated and decaffeinated coffee. Further, caffeinated coffee intake was associated with higher body weight (β= 0.018, P = 0.02), but total coffee intake was associated with a lower truncal to limb fat ratio before and after adjusting for BMI (β= -0.057, P = 0.03). We did not observe evidence of association with incident T2D (HR =0.63; 95% CI 0.15-2.50). Higher coffee intake was associated with improved post-load glucose metabolism and insulin sensitivity, and lower truncal adiposity. The figure displays result estimates of linear mixed models. Asterisks represent associations P &lt; 0.05.

Impaired plasma glucose clearance is a key determinant of fasting hyperglycemia in people with obesity.

The objective of this study was to evaluate the relative importance of the basal rate of glucose appearance (Ra) in the circulation and the basal rate of plasma glucose clearance in determining fasting plasma glucose concentration in people with obesity and different fasting glycemic statuses. The authors evaluated basal glucose kinetics in 33 lean people with normal fasting glucose (<100 mg/dL; Lean < 100 group) and 206 people with obesity and normal fasting glucose (Ob < 100 group, n = 118), impaired fasting glucose (100-125 mg/dL; Ob 100-125 group, n = 66), or fasting glucose diagnostic of diabetes (≥126 mg/dL; Ob ≥ 126 group, n = 22). Although there was a large (up to three-fold) range in glucose Ra within each group, the ranges in glucose concentration in the Lean < 100, Ob < 100, and Ob 100-125 groups were small because of a close relationship between glucose Ra and clearance rate. However, the glucose clearance rate at any Ra value was lower in the hyperglycemic than the normoglycemic groups. In the Ob ≥ 126 group, plasma glucose concentration was primarily determined by glucose Ra, because glucose clearance was markedly attenuated. Fasting hyperglycemia in people with obesity represents a disruption of the precisely regulated integration of glucose production and clearance rates.

Levodopa attenuates the feed intake reduction caused by ergot alkaloids in cattle.

Consumption of ergot alkaloids from endophyte-infected tall fescue results in losses to the livestock industry in many countries and a means to mitigate these losses is needed. The objective of this study was to evaluate intra-abomasal infusion of the dopamine precursor, levodopa (L-DOPA), on dopamine metabolism, feed intake, and serum metabolites of steers exposed to ergot alkaloids. Twelve Holstein steers (344.9 ± 9.48kg) fitted with ruminal cannula were housed with a cycle of heat challenge during the daytime (32 °C) and thermoneutral at night (25 °C). The steers received a basal diet of alfalfa cubes containing equal amounts of tall fescue seed composed of a mixture of endophyte-free (E-) or endophyte-infected tall fescue seeds (E+) equivalent to 15 µg ergovaline/kg body weight (BW) for 9d followed by intra-abomasal infusion of water (L-DOPA-) or levodopa (L-DOPA+; 2mg/kg BW) for an additional 9d. Afterward, the steers were pair-fed for 5d to conduct a glucose tolerance test. The E+ treatment decreased (P = 0.005) prolactin by approximately 50%. However, prolactin increased (P = 0.050) with L-DOPA+. Steers receiving E+ decreased (P < 0.001) dry matter intake (DMI); however, when supplemented with L-DOPA+ the decrease in DMI was less severe (L-DOPA × E, P = 0.003). Also, L-DOPA+ infusion increased eating duration (L-DOPA × E, P = 0.012) when steers were receiving E+. The number of meals, meal duration, and intake rate were not affected (P > 0.05) by E+ or L-DOPA+. The L-DOPA+ infusion increased (P < 0.05) free L-DOPA, free dopamine, total L-DOPA, and total dopamine. Conversely, free epinephrine and free norepinephrine decreased (P < 0.05) with L-DOPA+. Total epinephrine and total norepinephrine were not affected (P > 0.05) by L-DOPA+. Ergot alkaloids did not affect (P > 0.05) circulating free or total L-DOPA, dopamine, or epinephrine. However, free and total norepinephrine decreased (P = 0.046) with E+. Glucose clearance rates at 15 to 30min after glucose infusion increased with L-DOPA+ (P < 0.001), but not with E+ (P = 0.280). Administration of L-DOPA as an agonist therapy to treat fescue toxicosis provided a moderate increase in DMI and eating time and increased plasma glucose clearance for cattle dosed with E+ seed.

Glucocorticoid excess and insulin resistance in rat models of vascular contributions to cognitive impairment and dementia

AbstractBackgroundHypertension and insulin resistance are major risk factors for the development of dementia. While insulin resistance is considered an important risk factor for the development of hypertension and dementia, little consideration has been given to the idea that vascular disease could initiate insulin resistance and fuel a destructive cycle that hastens dementia. We previously showed that bilateral carotid artery stenosis results in HPA‐axis dysfunction and insulin resistance (Lansdell et al., 2022). We hypothesized that hypertension would also cause glucocorticoid excess and insulin resistance.MethodTo test this hypothesis, we measured fecal corticosterone and the expression of steroid biosynthetic genes in the adrenal glands of six‐month‐old spontaneously hypertensive rat/stroke‐prone (SHRSP) and normotensive Sprague Dawley (SD) rats. To assess glycemic control, rats were subjected to glucose and insulin tolerance tests.ResultSHRSP were hypertensive and cognitively impaired. Corticosterone was elevated in hypertensive compared to normotensive rats (Male SD vs. SHRSP: 167±29 pg/g vs.1091±166 pg/g, P&lt;0.0001; Female SD vs. SHRSP: 134±19 pg/g vs. 376±47 pg/g, P = 0.0017). Adrenal CYP11B1 mRNA expression was increased in SHRSP (Males 14.44±1.44, P = 0.0009; Females 710±59, P = 0.0016). STARD1 mRNA expression provided a marker of HPA negative feedback. Male SHRSPs had decreased STARD1 mRNA expression (0.56±0.09, P = 0.0217). However, female SHRSPs had increased STARD1 mRNA expression (12.5± 2.25, P = 0.0028). Female, but not male, hypertensive rats had increased fasting blood glucose, decreased fasting insulin, and reduced rates of glucose clearance (female SD vs. SHRSP: 73±6 vs. 92±4 mg/dL glucose, P = 0.0045; 33±2.0 vs. 12±5 pmol/L insulin, P = 0.0111; AUC 185±37 vs. 279±27 mg/dL/h, P = 0.0368). When fasting rats were challenged with insulin, both male and female hypertensive rats had decreased clearance of glucose compared to normotensive rats (Male SD vs. SHRSP AUC 87 ± 2 vs. 58 ± 4 mg/dL/h, P&lt; 0.0001, Female SD vs. SHRSP AUC 82 ± 2 vs. 68 ± 3 mg/dL/h, P = 0.0007).ConclusionThese results indicate that hypertension is associated with impaired HPA function and insulin resistance, with female hypertensive rats developing hyperglycemia at an earlier age than males.

Changes to insulin sensitivity in glucose clearance systems and redox following dietary supplementation with a novel cysteine-rich protein: A pilot randomized controlled trial in humans with type-2 diabetes

We recently developed a novel keratin-derived protein (KDP) rich in cysteine, glycine, and arginine, with the potential to alter tissue redox status and insulin sensitivity. The KDP was tested in 35 human adults with type-2 diabetes mellitus (T2DM) in a 14-wk randomised controlled pilot trial comprising three 2×20 g supplemental protein/day arms: KDP-whey (KDPWHE), whey (WHEY), non-protein isocaloric control (CON), with standardised exercise. Outcomes were measured morning fasted and following insulin-stimulation (80 mU/m2/min hyperinsulinaemic-isoglycaemic clamp). With KDPWHE supplementation there was good and very-good evidence for moderate-sized increases in insulin-stimulated glucose clearance rate (GCR; 26%; 90% confidence limits, CL 2%, 49%) and skeletal-muscle microvascular blood flow (46%; 16%, 83%), respectively, and good evidence for increased insulin-stimulated sarcoplasmic GLUT4 translocation (18%; 0%, 39%) vs CON. In contrast, WHEY did not effect GCR (-2%; -25%, 21%) and attenuated HbA1c lowering (14%; 5%, 24%) vs CON. KDPWHE effects on basal glutathione in erythrocytes and skeletal muscle were unclear, but in muscle there was very-good evidence for large increases in oxidised peroxiredoxin isoform 2 (oxiPRX2) (19%; 2.2%, 35%) and good evidence for lower GPx1 concentrations (-40%; -4.3%, -63%) vs CON; insulin stimulation, however, attenuated the basal oxiPRX2 response (4%; -16%, 24%), and increased GPx1 (39%; -5%, 101%) and SOD1 (26%; -3%, 60%) protein expression. Effects of KDPWHE on oxiPRX3 and NRF2 content, phosphorylation of capillary eNOS and insulin-signalling proteins upstream of GLUT4 translocation AktSer437 and AS160Thr642 were inconclusive, but there was good evidence for increased IRSSer312 (41%; 3%, 95%), insulin-stimulated NFκB-DNA binding (46%; 3.4%, 105%), and basal PAK-1Thr423/2Thr402 phosphorylation (143%; 66%, 257%) vs WHEY. Our findings provide good evidence to suggest that dietary supplementation with a novel edible keratin protein in humans with T2DM may increase glucose clearance and modify skeletal-muscle tissue redox and insulin sensitivity within systems involving peroxiredoxins, antioxidant expression, and glucose uptake.

Genetic Deletion of DNAJB3 Using CRISPR-Cas9, Produced Discordant Phenotypes.

Several pathways and/or genes have been shown to be dysregulated in obesity-induced insulin resistance (IR) and type 2 diabetes (T2D). We previously showed, for the first time, impaired expression of DNAJB3 mRNA and protein in subjects with obesity, which was concomitant with increased metabolic stress. Restoring the normal expression of DNAJB3 attenuated metabolic stress and improved insulin signaling both in vivo and in vitro, suggesting a protective role of DNAJB3 against obesity and T2D. The precise underlying mechanisms remained, however, unclear. This study was designed to confirm the human studies in a mouse model of dietary obesity-induced insulin resistance, and, if validated, to understand the underlying mechanisms. We hypothesized that mice lacking DNAJB3 would be more prone to high-fat (HF)-diet-induced increase in body weight and body fat, inflammation, glucose intolerance and insulin resistance as compared with wild-type (WT) littermates. Three DNAJB3 knockout (KO) lines were generated (KO 30, 44 and 47), using CRISPR-Cas9. Male and female KO and WT mice were fed a HF diet (45% kcal fat) for 16 weeks. Body weight was measured biweekly, and a glucose tolerance test (GTT) and insulin tolerance test (ITT) were conducted at week 13 and 14, respectively. Body composition was determined monthly by nuclear magnetic resonance (NMR). Following euthanasia, white adipose tissue (WAT) and skeletal muscle were harvested for further analyses. Compared with WT mice, male and female KO 47 mice demonstrated higher body weight and fat mass. Similarly, KO 47 mice also showed a slower rate of glucose clearance in GTT that was consistent with decreased mRNA expression of the GLUT4 gene in WAT but not in the muscle. Both male and female KO 47 mice exhibited higher mRNA levels of the pro-inflammatory marker TNF-a in WAT only, whereas increased mRNA levels of MCP1 chemokine and the ER stress marker BiP/Grp78 were observed in male but not in female KO 47 mice. However, we did not observe the same changes in the other KO lines. Taken together, the phenotype of the DNAJB3 KO 47 mice was consistent with the metabolic changes and low levels of DNAJB3 reported in human subjects. These findings suggest that DNAJB3 may play an important role in metabolic functions and glucose homeostasis, which warrants further phenotyping and intervention studies in other KO 47 and other KO mice, as well as investigating this protein as a potential therapeutic target for obesity and T2D.

Supplementation of an organic mineral source modulated metabolic profile, insulin sensitivity, and oxidative stress in dairy calves with different birth body weights

The present study was conducted to investigate the effects of partial replacement of inorganic minerals (IM) with advanced chelated minerals (ACMS) in the starter diets of calves of different birth body weights (BBW) on metabolic indices and glucose tolerance test. Fifty-two Holstein calves were assigned to one of 4 treatments in a 2 × 2 factorial arrangement with two mineral sources (IM or ACMS) and two BBW (low or normal birth weight; LBW or NBW). Calves were weaned on day 56 and remained in the study until day 71 of the study. Blood samples for blood metabolite analysis were collected from the jugular vein on days 30, 60, and 70 of the study, and for hematology on days 36, 56, and 70. The results showed that the interaction of starter mineral sources (MS) and BBW affected the overall plasma concentration of β-hydroxybutyrate (BHB), with the highest value being obtained during treatment with LBW-ACMS. In addition, an interaction between MS and BBW was observed in plasma insulin concentrations, with LBW-IM calves having the lowest concentrations compared to the other treatments. Plasma albumin concentrations were lower in LBW calves than in NBW calves. In addition, NBW calves had greater plasma concentrations of glucose (day 60), insulin (day 30), BHB (day 30), and malondialdehyde (MDA; day 60 and the overall period) than LBW calves, while total antioxidant capacity (TAC) tended to reverse at day 70. The ACMS starter increased plasma glucose concentration at day 30 and tended to increase plasma BHB concentration in the overall period. In addition, plasma MDA concentrations were lower in calves receiving ACMS than in calves receiving IM during the overall period. NBW calves tended to have more eosinophils (day 70), basophils (day 36), and erythrocytes (RBC, day 56, and the overall period) in plasma than LBW calves. Regardless of BBW, feeding ACMS starter increased white blood cells (WBC), neutrophils, and eosinophils at day 70 and also tended to increase neutrophils during the overall period compared with the IM groups. Red blood cell concentrations were greater in calves fed ACMS than in calves fed IM during the overall period. Glucose tolerance test showed that basal glucose concentration and clearance rate (CR) of glucose tended to be lower and higher, respectively, in calves fed ACMS than in calves fed IM. ACMS supplementation increased basal concentrations and also tended to increase maximum insulin concentrations compared with IM supplementation. In addition, calves receiving ACMS starter had greater plasma insulin area under the curve (AUC) and CR compared with calves receiving IM. Feeding ACMS tended to increase the ratio CR of insulin to CR of glucose and increased the AUC of insulin to AUC of glucose compared with feeding IM. Overall, feeding ACMS resulted in a decrease in plasma MDA concentration and an increase in neutrophil concentration, suggesting that ACMS may improve immune function in these calves. A potential insulinotropic effect was noted with ACMS feeding, which was accompanied by an improvement in glucose control rate. This is likely due to higher bioavailability of chelated minerals such as Zn and should be further investigated.

222-OR: Metformin Reduces Fasting Glycemia in Well-Controlled Type 2 Diabetes by Promoting Aerobic Glycolysis Independent of Decreasing Endogenous Glucose Production

It is well established that metformin improves glycemic control in individuals with poorly-controlled type 2 diabetes (T2D) by reducing rates of endogenous glucose production (EGP) mediated by inhibition of hepatic gluconeogenesis. However, the mechanism by which metformin reduces blood glucose levels in well-controlled individuals with T2D is still unknown. To address this question, we examined rates of EGP, lactate turnover and hepatic triglyceride (TAG), ATP and glycogen content in near-normoglycemic individuals with T2D (n=10, HbA1c 7±1%) with (M+; 1000 mg bid x 2 wks) and without (M-; 2 wks) metformin treatment using the PINTA method with [2H7]glucose and [3-13C]lactate tracer infusions in combination with 1H- /31P- /13C- magnetic resonance spectroscopy. Metformin treatment did not affect rates of EGP, but reduced fasting plasma glucose concentrations by 30% (p&amp;lt;0.01 vs. M-), which could be attributed to increased rates of glucose clearance (+18%, p&amp;lt;0.005 vs. M-) resulting in increased lactate production (+14%, p&amp;lt;0.01 vs. M-). These changes were associated with decreased hepatic ATP content (-20%, p&amp;lt;0.05 vs. M-), increased hepatic glycogen content (+40%, p&amp;lt;0.05 vs. M-) and no changes in hepatic TAG content. Conclusion: In contrast to the glucose-lowering effect of metformin in poorly-controlled T2D, which is due to reductions in gluconeogenesis, this study demonstrates that in well-controlled T2D metformin reduces fasting glycemia - independent of reductions in EGP - primarily by increasing rates of aerobic glycolysis as reflected by increased peripheral glucose clearance and lactate production as well as reduced hepatic ATP content, which is consistent with metformin-induced inhibition of mitochondrial electron transport chain activity. Disclosure T.Sarabhai: None. T.E.Lamoia: None. S.Friesl: None. M.Jonuscheit: None. K.Petersen: Advisory Panel; Novo Nordisk, Research Support; Merck Sharp &amp; Dohme Corp., Gilead Sciences, Inc. G.I.Shulman: Consultant; Novo Nordisk, DiCerna Pharmaceuticals, Inc., Bayer Consumer Care AG, Kriya Therapeutics, Arrowhead Pharmaceuticals, Inc., ESPERION Therapeutics, Inc., Other Relationship; AstraZeneca, Merck &amp; Co., Inc., Janssen Research &amp; Development, LLC, iMetabolic Biopharma Corporation, Maze Therapeutics, 89bio, Inc., Equator Therapeutics, Inc., Generian Pharmaceuticals, Fortress Biotech, Inc., OrsoBio, Aro Biotherapeutics Company, Stock/Shareholder; Levels Health, Inc. M.Roden: Advisory Panel; Eli Lilly and Company, Consultant; TARGET PharmaSolutions, Inc., Research Support; Boehringer-Ingelheim, Novo Nordisk, Novartis, Sanofi.

Acute sub-diaphragmatic anterior vagus nerve stimulation increases peripheral glucose uptake in anaesthetized rats

The sub-diaphragmatic vagus innervates various organs involved in the control of glucose homeostasis including the liver, pancreas and the intestines. In the current study, we investigated the effect of acute electrical stimulation of the anterior trunk of the sub-diaphragmatic vagus on glucose fluxes in anaesthetized adult male rats.After overnight fast, rats underwent either vagus nerve stimulation (VNS+, n = 11; rectangular pulses at 5 Hz, 1.5 mA, 1 msec pulse width) or sham stimulation (VNS-; n = 11) for 120 min under isoflurane anesthesia. Before stimulation, the rats received an i.v. bolus of 1 mL/kg of a sterilized aqueous solution containing 125 mg/mL of D-[6,6-2H2] glucose. Endogenous glucose production (EGP) and glucose clearance rate (GCR) were calculated by kinetic analysis from the wash-out of injected D-[6,6–2H2]glucose from the circulation.VNS+ resulted in lower glucose levels compared to the VNS- group (p < 0.05), with similar insulin levels. EGP was similar in both groups, but the GCR was higher in the VNS+ group compared to the VNS- group (p < 0.001). Circulating levels of the sympathetic transmitter norepinephrine were reduced by VNS+ relative to VNS- treatment (p < 0.01).It is concluded that acute anterior sub-diaphragmatic VNS causes stimulation of peripheral glucose uptake, while plasma insulin levels remained similar, and this is associated with lower activity of the sympathetic nervous system.

Dual amylin and calcitonin receptor agonist treatment improves insulin sensitivity and increases muscle-specific glucose uptake independent of weight loss

Dual amylin and calcitonin receptor agonists (DACRAs) are known to induce significant weight loss as well as improve glucose tolerance, glucose control, and insulin action in rats. However, to what extent DACRAs affect insulin sensitivity beyond that induced by weight loss and if DACRAs affect glucose turnover including tissue-specific glucose uptake is still unknown. Hyperinsulinemic glucose clamp studies were carried out in pre-diabetic ZDSD and diabetic ZDF rats treated with either the DACRA KBP or the long-acting DACRA KBP-A for 12 days. The glucose rate of disappearance was assessed using 3-3H glucose and tissue-specific glucose uptake was evaluated using 14C-2-deoxy-D-glucose (14C-2DG). In diabetic ZDF rats, KBP treatment significantly reduced fasting blood glucose and improved insulin sensitivity independent of weight loss. Furthermore, KBP increased the rate of glucose clearance, likely by increasing glucose storage, but without altering the endogenous glucose production. This was confirmed in pre-diabetic ZDSD rats. Direct assessment of tissue-specific glucose uptake showed, that both KBP and KBP-A significantly increased glucose uptake in muscles. In summary, KBP treatment significantly improved insulin sensitivity in diabetic rats and markedly increased glucose uptake in muscles. Importantly, in addition to their well-established weight loss potential, the KBPs have an insulin-sensitizing effect independent of weight loss, highlighting DACRAs as promising agents for the treatment of type 2 diabetes and obesity.

Colostrum insulin supplementation to neonatal Holstein bulls affects small intestinal histomorphology, mRNA expression, and enzymatic activity with minor influences on peripheral metabolism

The objectives of this study were to evaluate how varying colostral insulin concentrations influenced small intestinal development and peripheral metabolism in neonatal Holstein bulls. Insulin was supplemented to approximately 5× (70.0 μg/L; n = 16) or 10× (149.7 μg/L; n = 16) the basal colostrum insulin (12.9 μg/L; BI, n = 16) concentration to maintain equivalent macronutrient intake (crude fat: 4.1 ± 0.06%; crude protein: 11.7 ± 0.05%; and lactose: 1.9 ± 0.01%) among treatments. Colostrum was fed at 2, 14, and 26 h postnatal and blood metabolites and insulin concentration were measured at 0, 30, 60, 90, 120, 180, 240, 360, 480, and 600 min postprandial respective to the first and second colostrum meal. At 30 h postnatal, a subset of calves (n = 8/treatment) were killed to excise the gastrointestinal and visceral tissues. Gastrointestinal and visceral gross morphology and dry matter and small intestinal histomorphology, gene expression, and carbohydrase activity were assessed. Insulin supplementation tended to linearly reduce the glucose clearance rate following the first meal, whereas after the second meal, supplementation linearly increased the rate of glucose absorption and nonesterified fatty acid clearance rate, decreased the time to maximum glucose concentrations, and decreased the time to reach minimum nonesterified fatty acid concentrations. Additionally, insulin clearance rate was linearly increased by insulin supplementation following the second colostrum feeding. However, there were no overall differences between treatments in the concentrations of glucose, nonesterified fatty acids, or insulin in plasma or serum. With respect to macroscopic intestinal development, dry rumen tissue mass linearly decreased when insulin was supplemented in colostrum, and supplementation linearly increased duodenal dry tissue density (g dry matter/cm) while tending to increase duodenal dry tissue weight. Increasing the colostrum insulin concentration improved small intestinal histomorphological development in the distal small intestine, as ileal villi height and mucosal-serosal surface area index were increased by supplementing insulin. Lactase enzymatic activity linearly increased in the proximal jejunum while ileal isomaltase activity linearly decreased with insulin supplementation. These data indicate that changes in colostrum insulin concentrations rapidly affect gastrointestinal growth prioritization and carbohydrase activity. The changes in gastrointestinal ontology result in minor changes in postprandial metabolite availability and clearance.

Effect of &lt;i&gt;Gymnema sylvestre&lt;/i&gt; Extract on the Regulation of AMPK-GLUT4 Mediated Signaling Pathway on Insulin Resistance in a PCOS Rat Model

This study was intended to assess the effect of Gymnema sylvestre leaf extract on the AMPK-GLUT4 mediated signalling pathway on insulin resistance in polycystic ovarian syndrome-induced rats. For the induction of PCOS in rats, 1 mg/kg of letrozole was given orally for 21 days, after that metformin (300 mg/kg), Gymnema sylvestre leaf extract (200 mg/kg, and 400 mg/kg p. o.) were administered for further 28 days. Letrozole-induced PCOS rats illustrated significant estrus irregularity, and sex hormonal abnormality, and developed insulin resistance as indicated by increased fasting glucose levels, an increased rate of glucose clearance, and also decreases in GLUT4 and AMPK mRNA expression in ovarian cells. Ovarian histology in PCOS rats also showed many follicular cysts, atretic follicles, and the absence of the corpus luteum. These changes were significantly reversed by the treatment of G. sylvestre in a dose-dependent manner. It might be mediated through its insulin resistance modulating property by the activation of AMPK &amp; GLUT4 expression on ovarian endometrial cells.

Glucocorticoid excess and insulin resistance in aged spontaneously hypertensive rats/stroke-prone

Vascular diseases cause chronic cerebral hypoperfusion and neuronal injury and are the second most common cause of dementia. A significant cause of chronic cerebral hypoperfusion is hypertension. Insulin resistance is an important risk factor for hypertension. Aside from age, insulin resistance is also the most important risk factor for the development of dementia. While Insulin resistance is considered an important risk factor for the development of hypertension and dementia, little consideration has been given to the idea that hypertension could initiate insulin resistance and fuel a destructive cycle that hastens dementia. We hypothesized that hypertension initiates insulin resistance through sustained activation of the hypothalamic-pituitary-adrenal axis. To test this hypothesis, we measured corticosterone and the expression of steroid biosynthetic genes in six-month-old spontaneously hypertensive rat/stroke-prone (SHRSP) and normotensive Sprague Dawley (SD) rats. To measure glycemic control, rats were subjected to glucose tolerance and insulin tolerance tests. SHRSP were hypertensive and cognitively impaired. SHRSPs had increased corticosterone compared to SD (Male SD vs. SHRSP: 167±29 pg/g vs.1091±166 pg/g, P&lt;0.0001; Female SD vs. SHRSP: 134±19 pg/g vs. 376±47 pg/g, P=0.0017). Adrenal CYP11B1 mRNA expression was increased in SHRSP (Males 14.44±1.44, P=0.0009; Females 710±59, P=0.0016). STARD1 mRNA expression provided a marker of HPA negative feedback. Male SHRSPs had decreased STARD1 mRNA expression (0.56±0.09, P = 0.0217). However, female SHRSPs had increased STARD1 mRNA expression (12.5± 2.25, P=0.0028). Female, but not male, SHRSPs had increased fasting blood glucose, decreased fasting insulin, and reduced rates of glucose clearance (SD vs. SHRSP: 73±6 vs. 92±4 mg/dL glucose, P=0.0045; 33±2.0 vs. 12±5 pmol/L insulin, P=0.0111; AUC 185±37 vs. 279±27 mg/dL/h, P=0.0368). When fasting rats were challenged with insulin, both male and female SHRSPs had decreased clearance of glucose compared to SDs (Male SD vs. SHRSP AUC 87 ± 2 vs. 58 ± 4 mg/dL/h, P&lt; 0.0001, Female SD vs. SHRSP AUC 82 ± 2 vs. 68 ± 3 mg/dL/h, P=0.0007). These results indicate that hypertension is associated with impaired HPA function and insulin resistance, with female SHRSP succumbing faster to hyperglycemia than males. Alzheimer's Association Research Fellowship This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.