Lower Endogenous Glucose Production Research Articles

Effects of Sodium Thiosulfate During Resuscitation From Trauma-and-Hemorrhage in Cystathionine Gamma Lyase (CSE) Knockout Mice.

Sodium thiosulfate (Na2S2O3) is a clinically established drug with antioxidant and sulphide-releasing properties. Na2S2O3 mediated neuro- and cardioprotective effects in ischemia/reperfusion models and anti-inflammatory effects in LPS-induced acute lung injury. Moreover, Na2S2O3 improved lung function during resuscitation from hemorrhagic shock in swine with pre-existing atherosclerosis, characterized by decreased expression of cystathionine γ-lyase (CSE), a major source of hydrogen sulfide (H2S) synthesis in the vasculature. Based on these findings, we investigated the effects of Na2S2O3 administration during resuscitation from trauma-and-hemorrhage in mice under conditions of whole body CSE deficit. After blast wave-induced blunt chest trauma and surgical instrumentation, CSE knockout (CSE-/-) mice underwent 1 h of hemorrhagic shock (MAP 35 ± 5 mm Hg). At the beginning of resuscitation comprising retransfusion, norepinephrine support and lung-protective mechanical ventilation, animals received either i.v. Na2S2O3 (0.45 mg g-1, n = 12) or vehicle (saline, n = 13). Hemodynamics, acid-base status, metabolism using stable isotopes, and visceral organ function were assessed. Blood and organs were collected for analysis of cytokines, mitochondrial respiratory capacity, and immunoblotting. Na2S2O3 treatment improved arterial paO2 (P = 0.03) coinciding with higher lung tissue glucocorticoid receptor expression. Norepinephrine requirements were lower in the Na2S2O3 group (P < 0.05), which was associated with lower endogenous glucose production and higher urine output. Na2S2O3 significantly increased renal tissue IκBα and heme oxygenase-1 expression, whereas it lowered kidney IL-6 and MCP-1 levels. Na2S2O3 exerted beneficial effects during resuscitation of murine trauma-and-hemorrhage in CSE-/- mice, confirming and extending the previously described organ-protective and anti-inflammatory properties of Na2S2O3. The findings make Na2S2O3 a potentially promising therapeutic option in the context of impaired CSE activity and/or reduced endogenous H2S availability.

1898-P: Colonic Short-Chain Fatty Acids Lower Endogenous Glucose Production

Hyperglycemia is a hallmark characteristic of diabetes, resulting in elevated blood glucose levels, due in part to a chronic elevation in endogenous hepatic glucose production (GP). Recent work has highlighted the gut microbiota as a salient contributor to energy and glucose homeostasis. One potential mechanism may be through increased short-chain fatty acid (SCFA) signaling mechanisms. SCFAs are bacterial breakdown products of nondigestible dietary fibers, occurring mainly in the colon, and have been shown to improve glucose homeostasis. Interestingly, recent work has highlighted that ingested nutrients can activate small intestinal nutrient-sensing mechanisms to lower hepatic glucose production via a neuronal gut-brain-liver axis mediated via gut peptide signaling. However, no one has directly tested whether colonic SCFAs can regulate GP via a similar colonic neuronal mechanism. To test this, we directly infused SCFAs (acetate, propionate, butyrate; 10mM or 100mM) into the colon during a pancreatic euglycemic clamp, the gold standard for measuring endogenous glucose production and uptake, in high-fat diet (HFD) fed rats that we previously found to have diminished levels of SCFAs in the large intestine. Administration of either acetate, propionate or butyrate (10mM or 100mM) directly into the colon of HFD-fed rats resulted in an increased glucose infusion rate needed to maintain euglycemia, which was due to a significant decrease in endogenous GP compared to saline infusion. Furthermore, we found that this was mediated via GLP-1 receptor signaling, as co-administration of exendin-9 with either SCFA (10mM) abolished the GP-lowering effect. Additionally, portal levels of GLP-1 were significantly increased at the end of the pancreatic clamp in rats receiving infusion of acetate, butyrate, or propionate compared to saline. Taken together, this work demonstrates that colonic SCFAs can activate a GLP-1 receptor mediated pathway in the colon to lower endogenous GP. Disclosure A.I.L. Lane: None. S.N. Weninger: None. F. Duca: None. Funding National Institutes of Health (R01DK121804)

115-OR: Epinephrine Contributes to Hypoglycemia-Associated Autonomic Failure (HAAF)

Recurrent hypoglycemia leads to HAAF, with blunted counterregulatory hormone responses to subsequent hypoglycemic episodes. A recent report suggested inter-individual differences in susceptibility to HAAF (JCEM 102:3571, 2017). Since adrenergic receptor blockade prevents HAAF (Diabetes 60:602, 2011), we investigated to what extent the rises in plasma epinephrine (EPI) associated with hypoglycemia predict the development of HAAF. Healthy non-diabetic subjects (n=18, age 43±2years, BMI 25±1 kg/m2) underwent two 2-hour hypoglycemic clamp studies (nadir 54mg/dl; 0-2h and 4-6 h) on Day 1 followed by a third 2-hour hypoglycemic clamp on Day 2. Twelve subjects (67%) developed HAAF by the third episode, as defined by at least 20% reductions in peak EPI levels (peak EPI 1st vs. 3rd episode: HAAF subjects 1072±156 vs. 530±87pg/ml, p&amp;lt;0.001). Importantly, peak EPI levels during the 1st hypoglycemic episode were ∼83% higher in the subjects who developed HAAF compared to those who did not (p=0.02). To specifically define the role of EPI in the pathogenesis of HAAF, we challenged an additional seven non-diabetic subjects (age 32±4 years, BMI 25±1 kg/m2) with two 2-hour infusions of EPI (0.03 μg/kg/min;0-2h and 4-6 h) on Day 1 followed by 200-minute stepped hypoglycemic clamps (90, 80, 70 and 60 mg/dl, each for 50 minutes) on Day 2. Compared to saline, EPI infusion on Day 1 induced 40% and 28% reductions in epinephrine response to hypoglycemia at the 70 and 60 mg/dl glucose steps on Day 2, respectively (all p&amp;lt;0.05). There were parallel reductions in hypoglycemic symptoms (all p&amp;lt;0.05). Furthermore, the rate of glucose infusion was higher at all steps after EPI infusion (all p&amp;lt;0.05), consistent with a trend towards lower endogenous glucose production (6,6-D2-glucose). Thus, rises in EPI similar to those seen with hypoglycemia reproduce key features of HAAF in non-diabetic subjects. Marked inter-individual variability in EPI levels in response to hypoglycemia may explain why some people are more prone to develop HAAF. Disclosure E. Lontchi Yimagou: None. S. Aleksic: None. L. Upadhyay: None. S. Sharma: None. M. Carey: None. A. Goyal: None. J. You: None. R. Hulkower: None. S. Murthi: None. W.G. Mitchell: None. H. Shamoon: None. M. Hawkins: Other Relationship; Self; Novo Nordisk Inc. Funding American Diabetes Association (1-18-PMF-024 to E.L.Y.); National Institutes of Health (R01DK079974)

1846-P: The Insulin-Sensitizing Effects of Palmitic Acid Esters of Hydroxy Stearic Acids Involve Intertissue Communication

Palmitic Acid esters of Hydroxy Stearic Acids (PAHSAs), bioactive lipids with anti-inflammatory and antidiabetic effects, improve glucose tolerance and insulin sensitivity in insulin-resistant mice. We found that PAHSA treatment enhances insulin action to suppress endogenous glucose production (EGP) in chow and HFD mice and promotes glucose uptake in glycolytic muscle and heart in HFD-fed mice. We aimed to determine the mechanisms by which PAHSAs enhance hepatic insulin sensitivity. We examined both direct effects in hepatocytes and indirect effects resulting from augmentation of insulin-mediated suppression of WAT lipolysis. Here, we show that PAHSAs inhibit lipolysis in WAT explants to the same extent as insulin. PAHSAs also enhance the anti-lipolytic effect of insulin in vivo, as indicated by a 30% reduction in FFAs during the clamp in PAHSA-treated mice under conditions with no suppression in Vehicle treated mice. To determine whether lowering FFAs is necessary for PAHSA effects on insulin sensitivity, we infused intralipid during a hyperinsulinemic-euglycemic clamp. In chow-fed mice infused with intralipid, PAHSAs still have a partial effect to lower EGP (Intralipid: vehicle 12±0.8 vs. PAHSA 7±1.7 mg/kg/minute), whereas in HFD-fed mice, preventing PAHSA-induced FFA reduction blocks PAHSA effects on hepatic insulin sensitivity (EGP Intralipid: vehicle 13±0.6 vs. PAHSA 12±1.7 mg/kg/minute). Our mechanistic studies show that PAHSAs inhibit basal EGP and reduce glucagon stimulated EGP directly in isolated hepatocytes. This is mediated by a cAMP-dependent pathway involving Gα/i protein-coupled receptors. Hepatic phospho-CREB is also reduced by PAHSAs in vivo. Sum: PAHSAs enhance hepatic insulin sensitivity through direct and indirect actions involving inter-tissue communication between adipose tissue and liver. These data reveal new mechanisms underlying the beneficial effects of PAHSAs, which will clarify their roles in healthy and disease states. Disclosure P. Zhou: None. A. Santoro: None. O.D. Peroni: None. A.T. Nelson: None. A. Saghatelian: None. D. Siegel: None. B. Kahn: Advisory Panel; Self; Alterna Therapeutics, Inc., American Diabetes Association, Harrington Discovery Institute, Janssen Research &amp; Development. Consultant; Self; Ironwood Pharmaceuticals, Inc. Research Support; Self; National Institute of Diabetes and Digestive and Kidney Diseases. Funding American Diabetes Association (1-18-PDF-134 to P.Z.); National Institutes of Health (R01DK43051 to B.K.), (R01DK106210 to B.K., A.S.); JPB Foundation (to B.K.); American Heart Association (to A.T.N.)

Neuroendocrine inhibition of glucose production and resistance to cancer in dwarf mice

Pit1 null (Snell dwarf) and Proph1 null (Ames dwarf) mutant mice lack GH, PRL and TSH. Snell and Ames dwarf mice also exhibit reduced IGF-I, resistance to cancer and a longer lifespan than control mice. Endogenous glucose production during fasting is reduced in Snell dwarf mice compared to fasting control mice. In view of cancer cell dependence on glucose for energy, low endogenous glucose production may provide Snell dwarf mice with resistance to cancer. We investigated whether endogenous glucose production is lower in Snell dwarf mice during feeding. Inhibition of endogenous glucose production by glucose injection was enhanced in 12 to 14 month-old female Snell dwarf mice. Thus, we hypothesize that lower endogenous glucose production during feeding and fasting reduces cancer cell glucose utilization providing Snell dwarf mice with resistance to cancer. The elevation of circulating adiponectin, a hormone produced by adipose tissue, may contribute to the suppression of endogenous glucose production in 12 to 14 month-old Snell dwarf mice. We compared the incidence of cancer at time of death between old Snell dwarf and control mice. Only 18% of old Snell dwarf mice had malignant lesions at the time of death compared to 82% of control mice. The median ages at death for old Snell dwarf and control mice were 33 and 26 months, respectively. By contrast, previous studies showed a high incidence of cancer in old Ames dwarf mice at the time of death. Hence, resistance to cancer in old Snell dwarf mice may be mediated by neuroendocrine factors that reduce glucose utilization besides elevated adiponectin, reduced IGF-I and a lack of GH, PRL and TSH, seen in both Snell and Ames dwarf mice. Proteomics analysis of pituitary secretions from Snell dwarf mice confirmed the absence of GH and PRL, the secretion of ACTH and elevated secretion of Chromogranin B and Secretogranin II. Radioimmune assays confirmed that circulating Chromogranin B and Secretogranin II were elevated in 12 to 14 month-old Snell dwarf mice. In summary, our results in Snell dwarf mice suggest that the pituitary gland and adipose tissue are part of a neuroendocrine loop that lowers the risk of cancer during aging by reducing the availability of glucose.

The Role of Intramyocellular Lipids during Hypoglycemia in Patients with Intensively Treated Type 1 Diabetes

Endocrine defensive mechanisms provide for energy supply during hypoglycemia. Intramyocellular lipids (IMCL) were recently shown to contribute to energy supply during exercise. The objective of this study was to assess the contribution of IMCL compared with lipolysis and endogenous glucose production (EGP) to insulin-mediated hypoglycemia counterregulation in patients with type 1 diabetes mellitus (T1DM). This was a prospective explorative study performed in a university research facility. Six well-controlled T1DM (age, 29 +/- 4 yr; body mass index, 23.4 +/- 1.0 kg/m2; hemoglobin A1c, 6.3 +/- 0.1%) and six nondiabetic humans (controls; age, 28 +/- 2 yr; body mass index, 23.4 +/- 1.0 kg/m2; hemoglobin A1c, 5.1 +/- 0.1%) were studied. We performed 240-min hypoglycemic (approximately 3 mM)-hyperinsulinemic (0.8 mU/kg x min) clamps on separate days to measure: 1) systemic lipolysis ([2H5]glycerol turnover), EGP ([6,6-(2)H2]glucose), and local lipolysis in abdominal s.c. adipose tissue and gastrocnemius muscle (microdialysis); and 2) IMCL (by 1H nuclear magnetic resonance spectroscopy) in soleus and tibialis anterior muscle. The main outcome measures were changes in IMCL during prolonged hypoglycemia. At baseline, EGP, glycerol turnover, and IMCL were not different between the groups. During hypoglycemia, hormonal counterregulation was blunted in T1DM (peak: glucagon, 68 +/- 4 vs. 170 +/- 37 pg/ml; cortisol, 16 +/- 2 vs. 24 +/- 2 microg/dl; epinephrine, 274 +/- 84 vs. 597 +/- 212 pg/ml; all P < 0.05 vs. control). T1DM had approximately 50% lower EGP (4.6 +/- 0.6 vs. 10.9 +/- 0.5 micromol/kg x min; P < 0.005), but approximately 40% higher glycerol turnover (374 +/- 21 vs. 272 +/- 19 micromol/kg x min; P < 0.01). Glycerol concentrations in muscle (T1DM, 302 +/- 22 control, 346 +/- 17 micromol/liter) and adipose tissue (264 +/- 25 vs. 318 +/- 25 micromol/liter) did not differ between groups. IMCL in soleus and tibialis anterior muscle did not change from baseline during hypoglycemia. In well-controlled T1DM, impaired hypoglycemia counterregulation is associated with decreased glucose production and augmented whole body lipolysis, which cannot be explained by either hydrolysis of muscle triglycerides or increased abdominal s.c. adipose tissue lipolysis.