1
|
Warner SO, Wadian AM, Smith M, Farmer B, Dai Y, Sheanon N, Edgerton DS, Winnick JJ. Liver glycogen-induced enhancements in hypoglycemic counterregulation require neuroglucopenia. Am J Physiol Endocrinol Metab 2021; 320:E914-E924. [PMID: 33779306 PMCID: PMC8424545 DOI: 10.1152/ajpendo.00501.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 03/24/2021] [Accepted: 03/24/2021] [Indexed: 01/24/2023]
Abstract
Iatrogenic hypoglycemia is a prominent barrier to achieving optimal glycemic control in patients with diabetes, in part due to dampened counterregulatory hormone responses. It has been demonstrated that elevated liver glycogen content can enhance these hormonal responses through signaling to the brain via afferent nerves, but the role that hypoglycemia in the brain plays in this liver glycogen effect remains unclear. During the first 4 h of each study, the liver glycogen content of dogs was increased by using an intraportal infusion of fructose to stimulate hepatic glucose uptake (HG; n = 13), or glycogen was maintained near fasting levels with a saline infusion (NG; n = 6). After a 2-h control period, during which the fructose/saline infusion was discontinued, insulin was infused intravenously for an additional 2 h to bring about systemic hypoglycemia in all animals, whereas brain euglycemia was maintained in a subset of the HG group by infusing glucose bilaterally into the carotid and vertebral arteries (HG-HeadEu; n = 7). Liver glycogen content was markedly elevated in the two HG groups (43 ± 4, 73 ± 3, and 75 ± 7 mg/g in NG, HG, and HG-HeadEu, respectively). During the hypoglycemic period, arterial plasma glucose levels were indistinguishable between groups (53 ± 2, 52 ± 1, and 51 ± 1 mg/dL, respectively), but jugular vein glucose levels were kept euglycemic (88 ± 5 mg/dL) only in the HG-HeadEu group. Glucagon and epinephrine responses to hypoglycemia were higher in HG compared with NG, whereas despite the increase in liver glycogen, neither increased above basal in HG-HeadEu. These data demonstrate that the enhanced counterregulatory hormone secretion that accompanies increased liver glycogen content requires hypoglycemia in the brain.NEW & NOTEWORTHY It is well known that iatrogenic hypoglycemia is a barrier to optimal glycemic regulation in patients with diabetes. Our data confirm that increasing liver glycogen content 75% above fasting levels enhances hormonal responses to insulin-induced hypoglycemia and demonstrate that this enhanced hormonal response does not occur in the absence of hypoglycemia in the brain. These data demonstrate that information from the liver regarding glycogen availability is integrated in the brain to optimize the counterregulatory response.
Collapse
Affiliation(s)
- Shana O Warner
- Department of Internal Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Abby M Wadian
- Department of Internal Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Marta Smith
- Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Ben Farmer
- Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Yufei Dai
- Department of Internal Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Nicole Sheanon
- Department of Endocrinology, University of Cincinnati College of Medicine and Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Dale S Edgerton
- Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Jason J Winnick
- Department of Internal Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
| |
Collapse
|
2
|
Warner SO, Yao MV, Cason RL, Winnick JJ. Exercise-Induced Improvements to Whole Body Glucose Metabolism in Type 2 Diabetes: The Essential Role of the Liver. Front Endocrinol (Lausanne) 2020; 11:567. [PMID: 32982968 PMCID: PMC7484211 DOI: 10.3389/fendo.2020.00567] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/13/2020] [Indexed: 01/22/2023] Open
Abstract
Type 2 diabetes (T2D) is a metabolic disease characterized by obesity, insulin resistance, and the dysfunction of several key glucoregulatory organs. Among these organs, impaired liver function is recognized as one of the earliest contributors to impaired whole-body glucose homeostasis, with well-characterized hepatic insulin resistance resulting in elevated rates of hepatic glucose production (HGP) and fasting hyperglycemia. One portion of this review will provide an overview of how HGP is regulated during the fasted state in healthy humans and how this process becomes dysregulated in patients with T2D. Less well-appreciated is the liver's role in post-prandial glucose metabolism, where it takes up and metabolizes one-third of orally ingested glucose. An abundance of literature has shown that the process of hepatic glucose uptake is impaired in patients with T2D, thereby contributing to glucose intolerance. A second portion of this review will outline how hepatic glucose uptake is regulated during the post-prandial state, and how it becomes dysfunctional in patients with T2D. Finally, it is well-known that exercise training has an insulin-sensitizing effect on the liver, which contributes to improved whole-body glucose metabolism in patients with T2D, thereby making it a cornerstone in the management of the disease. To this end, the impact of exercise on hepatic glucose metabolism will be thoroughly discussed, referencing key findings in the literature. At the same time, sources of heterogeneity that contribute to inconsistent findings in the field will be pointed out, as will important topics for future investigation.
Collapse
Affiliation(s)
- Shana O. Warner
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Michael V. Yao
- Division of Endocrinology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Rebecca L. Cason
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Jason J. Winnick
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States
- *Correspondence: Jason J. Winnick
| |
Collapse
|
3
|
Gregory JM, Kraft G, Scott MF, Neal DW, Farmer B, Smith MS, Hastings JR, Madsen P, Kjeldsen TB, Hostrup S, Brand CL, Fledelius C, Nishimura E, Cherrington AD. Peripherally delivered hepatopreferential insulin analog insulin-406 mimics the hypoglycaemia-sparing effect of portal vein human insulin infusion in dogs. Diabetes Obes Metab 2019; 21:2294-2304. [PMID: 31183936 PMCID: PMC8132115 DOI: 10.1111/dom.13808] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 05/26/2019] [Accepted: 06/05/2019] [Indexed: 12/16/2022]
Abstract
AIMS We previously quantified the hypoglycaemia-sparing effect of portal vs peripheral human insulin delivery. The current investigation aimed to determine whether a bioequivalent peripheral vein infusion of a hepatopreferential insulin analog, insulin-406, could similarly protect against hypoglycaemia. MATERIALS AND METHODS Dogs received human insulin infusions into either the hepatic portal vein (PoHI, n = 7) or a peripheral vein (PeHI, n = 7) for 180 minutes at four-fold the basal secretion rate (6.6 pmol/kg/min) in a previous study. Insulin-406 (Pe406, n = 7) was peripherally infused at 6.0 pmol/kg/min, a rate determined to decrease plasma glucose by the same amount as with PoHI infusion during the first 60 minutes. Glucagon was fixed at basal concentrations, mimicking the diminished α-cell response seen in type 1 diabetes. RESULTS Glucose dropped quickly with PeHI infusion, reaching 41 ± 3 mg/dL at 60 minutes, but more slowly with PoHI and Pe406 infusion (67 ± 2 and 72 ± 4 mg/dL, respectively; P < 0.01 vs PeHI for both). The hypoglycaemic nadir (c. 40 mg/dL) occurred at 60 minutes with PeHI infusion vs 120 minutes with PoHI and Pe406 infusion. ΔAUCepinephrine during the 180-minute insulin infusion period was two-fold higher with PeHI infusion compared with PoHI and Pe406 infusion. Glucose production (mg/kg/min) was least suppressed with PeHI infusion (Δ = 0.79 ± 0.33) and equally suppressed with PoHI and Pe406 infusion (Δ = 1.16 ± 0.21 and 1.18 ± 0.17, respectively; P = NS). Peak glucose utilization (mg/kg/min) was highest with PeHI infusion (4.94 ± 0.17) and less with PoHI and Pe406 infusion (3.58 ± 0.58 and 3.26 ± 0.08, respectively; P < 0.05 vs Pe for both). CONCLUSIONS Peripheral infusion of hepatopreferential insulin can achieve a metabolic profile that closely mimics portal insulin delivery, which reduces the risk of hypoglycaemia compared with peripheral insulin infusion.
Collapse
Affiliation(s)
- Justin M. Gregory
- Ian Burr Division of Pediatric Endocrinology and Diabetes, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Melanie F. Scott
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Doss W. Neal
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Marta S. Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Jon R. Hastings
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Peter Madsen
- Global Research Technologies, Novo Nordisk A/S, Maaleov, Denmark
| | | | - Susanne Hostrup
- Global Research Technologies, Novo Nordisk A/S, Maaleov, Denmark
| | | | | | | | - Alan D. Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| |
Collapse
|
4
|
Gregory JM, Muldowney JA, Engelhardt BG, Tyree R, Marks-Shulman P, Silver HJ, Donahue EP, Edgerton DS, Winnick JJ. Aerobic exercise training improves hepatic and muscle insulin sensitivity, but reduces splanchnic glucose uptake in obese humans with type 2 diabetes. Nutr Diabetes 2019; 9:25. [PMID: 31474750 PMCID: PMC6717736 DOI: 10.1038/s41387-019-0090-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 07/30/2019] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Aerobic exercise training is known to have beneficial effects on whole-body glucose metabolism in people with type 2 diabetes (T2D). The responses of the liver to such training are less well understood. The purpose of this study was to determine the effect of aerobic exercise training on splanchnic glucose uptake (SGU) and insulin-mediated suppression of endogenous glucose production (EGP) in obese subjects with T2D. METHODS Participants included 11 obese humans with T2D, who underwent 15 ± 2 weeks of aerobic exercise training (AEX; n = 6) or remained sedentary for 15 ± 1 weeks (SED; n = 5). After an initial screening visit, each subject underwent an oral glucose load clamp and an isoglycemic/two-step (20 and 40 mU/m2/min) hyperinsulinemic clamp (ISO-clamp) to assess SGU and insulin-mediated suppression of EGP, respectively. After the intervention period, both tests were repeated. RESULTS In AEX, the ability of insulin to suppress EGP was improved during both the low (69 ± 9 and 80 ± 6% suppression; pre-post, respectively; p < 0.05) and high (67 ± 6 and 82 ± 4% suppression, respectively; p < 0.05) insulin infusion periods. Despite markedly improved muscle insulin sensitivity, SGU was reduced in AEX after training (22.9 ± 3.3 and 9.1 ± 6.0 g pre-post in AEX, respectively; p < 0.05). CONCLUSIONS In obese T2D subjects, exercise training improves whole-body glucose metabolism, in part, by improving insulin-mediated suppression of EGP and enhancing muscle glucose uptake, which occur despite reduced SGU during an oral glucose challenge.
Collapse
Affiliation(s)
- Justin M Gregory
- Ian M. Burr Division of Pediatric Endocrinology and Diabetes, Vanderbilt University School of Medicine, 1500 21st Ave, Suite 1514, Nashville, TN, 37212, USA
| | - James A Muldowney
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Brian G Engelhardt
- Division of Hematology and Oncology, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Regina Tyree
- Center for Human Nutrition, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Pam Marks-Shulman
- Section of Surgical Sciences, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Heidi J Silver
- Center for Human Nutrition, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - E Patrick Donahue
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Dale S Edgerton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Jason J Winnick
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0547, USA.
| |
Collapse
|
5
|
Gregory JM, Lautz M, Moore LM, Williams PE, Reddy P, Cherrington AD. Enterically delivered insulin tregopil exhibits rapid absorption characteristics and a pharmacodynamic effect similar to human insulin in conscious dogs. Diabetes Obes Metab 2019; 21:160-169. [PMID: 30095210 PMCID: PMC6281755 DOI: 10.1111/dom.13498] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 07/29/2018] [Accepted: 08/06/2018] [Indexed: 12/12/2022]
Abstract
AIMS Current therapy fails to emulate rapid (first-phase) insulin release in relation to a meal, a key defect in types 1 and 2 diabetes. We aimed to quantify the pharmacokinetic (PK) and pharmacodynamic (PD) profile of insulin tregopil, an enterically-absorbed insulin analog that restores the normal distribution of insulin between the hepatic portal and peripheral circulations. MATERIALS AND METHODS The PK and PD profiles of insulin tregopil were studied in overnight-fasted, catheterized, conscious canines using four approaches: (1) equimolar intraportal infusions of tregopil vs human insulin; (2) escalating doses of oral tregopil; (3) identical, consecutive enteric doses of tregopil; and (4) comparison of oral tregopil to inhaled and subcutaneous human insulin administration. RESULTS Equimolar intraportal infusions of tregopil and human insulin resulted in very similar PK profiles and PD profiles were nearly identical. Enteric delivery of tregopil brought about rapid absorption with tmax = 20 minutes in most cases. Median tmax was 20 minutes for oral tregopil and inhaled insulin and 88 minutes for subcutaneous human insulin. The time required for arterial plasma insulin levels to return to baseline was approximately 90, 210 and 360 minutes for oral tregopil, inhaled insulin and subcutaneous insulin, respectively. CONCLUSIONS Enterically delivered tregopil is rapidly absorbed and restores a portal-to-peripheral vascular distribution. These characteristics should improve postprandial hyperglycaemia in types 1 and 2 diabetes.
Collapse
Affiliation(s)
- Justin M. Gregory
- Vanderbilt Ian Burr Division of Pediatric Endocrinology and Diabetes, Vanderbilt University School of Medicine, Nashville, TN
| | - Margaret Lautz
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - L. Merkle Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Phillip E. Williams
- Section of Surgical Sciences, Vanderbilt University School of Medicine, Nashville, TN
| | | | - Alan D. Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| |
Collapse
|
6
|
Moore MC, Smith MS, Farmer B, Coate KC, Kraft G, Shiota M, Williams PE, Cherrington AD. Morning Hyperinsulinemia Primes the Liver for Glucose Uptake and Glycogen Storage Later in the Day. Diabetes 2018; 67:1237-1245. [PMID: 29666062 PMCID: PMC6014555 DOI: 10.2337/db17-0979] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 04/10/2018] [Indexed: 12/13/2022]
Abstract
We observed that a 4-h morning (AM) duodenal infusion of glucose versus saline doubled hepatic glucose uptake (HGU) and storage during a hyperinsulinemic-hyperglycemic (HIHG) clamp that afternoon (PM). To separate the effects of AM hyperglycemia versus AM hyperinsulinemia on the PM response, we used hepatic balance and tracer ([3-3H]glucose) techniques in conscious dogs. From 0 to 240 min, dogs underwent a euinsulinemic-hyperglycemic (GLC; n = 7) or hyperinsulinemic-euglycemic (INS; n = 8) clamp. Tracer equilibration and basal sampling occurred from 240 to 360 min, followed by an HIHG clamp (360-600 min; four times basal insulin, two times basal glycemia) with portal glucose infusion (4 mg ⋅ kg-1 ⋅ min-1). In the HIHG clamp, HGU (5.8 ± 0.9 vs. 3.3 ± 0.3 mg ⋅ kg-1 ⋅ min-1) and net glycogen storage (6.0 ± 0.8 vs. 2.9 ± 0.5 mg ⋅ kg-1 ⋅ min-1) were approximately twofold greater in INS than in GLC. PM hepatic glycogen content (1.9 ± 0.2 vs. 1.3 ± 0.2 g/kg body weight) and glycogen synthase (GS) activity were also greater in INS versus GLC, whereas glycogen phosphorylase (GP) activity was reduced. Thus AM hyperinsulinemia, but not AM hyperglycemia, enhanced the HGU response to a PM HIHG clamp by augmenting GS and reducing GP activity. AM hyperinsulinemia can prime the liver to extract and store glucose more effectively during subsequent same-day meals, potentially providing a tool to improve glucose control.
Collapse
Affiliation(s)
- Mary Courtney Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN
| | - Marta S Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN
| | - Katie C Coate
- Department of Nutrition and Dietetics, Samford University, Birmingham, AL
| | - Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Masakazu Shiota
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN
| | - Phillip E Williams
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN
- Department of Surgery, Vanderbilt University School of Medicine, Nashville, TN
| | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN
| |
Collapse
|
7
|
Honka MJ, Latva-Rasku A, Bucci M, Virtanen KA, Hannukainen JC, Kalliokoski KK, Nuutila P. Insulin-stimulated glucose uptake in skeletal muscle, adipose tissue and liver: a positron emission tomography study. Eur J Endocrinol 2018; 178. [PMID: 29535167 PMCID: PMC5920018 DOI: 10.1530/eje-17-0882] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVE Insulin resistance is reflected by the rates of reduced glucose uptake (GU) into the key insulin-sensitive tissues, skeletal muscle, liver and adipose tissue. It is unclear whether insulin resistance occurs simultaneously in all these tissues or whether insulin resistance is tissue specific. DESIGN AND METHODS We measured GU in skeletal muscle, adipose tissue and liver and endogenous glucose production (EGP), in a single session using 18F-fluorodeoxyglucose with positron emission tomography (PET) and euglycemic-hyperinsulinemic clamp. The study population consisted of 326 subjects without diabetes from the CMgene study cohort. RESULTS Skeletal muscle GU less than 33 µmol/kg tissue/min and subcutaneous adipose tissue GU less than 11.5 µmol/kg tissue/min characterized insulin-resistant individuals. Men had considerably worse insulin suppression of EGP compared to women. By using principal component analysis (PCA), BMI inversely and skeletal muscle, adipose tissue and liver GU positively loaded on same principal component explaining one-third of the variation in these measures. The results were largely similar when liver GU was replaced by EGP in PCA. Liver GU and EGP were positively associated with aging. CONCLUSIONS We have provided threshold values, which can be used to identify tissue-specific insulin resistance. In addition, we found that insulin resistance measured by GU was only partially similar across all insulin-sensitive tissues studied, skeletal muscle, adipose tissue and liver and was affected by obesity, aging and gender.
Collapse
Affiliation(s)
| | | | - Marco Bucci
- Turku PET Centre, Åbo Akademi UniversityTurku, Finland
| | - Kirsi A Virtanen
- Turku PET Centre, University of TurkuTurku, Finland
- Turku PET Centre, Institute of Public Health and Clinical NutritionUniversity of Eastern Finland, Kuopio, Finland
| | | | | | - Pirjo Nuutila
- Turku PET Centre, University of TurkuTurku, Finland
- Department of EndocrinologyTurku University Hospital, Turku, Finland
| |
Collapse
|
8
|
Gregory JM, Rivera N, Kraft G, Winnick JJ, Farmer B, Allen EJ, Donahue EP, Smith MS, Edgerton DS, Williams PE, Cherrington AD. Glucose autoregulation is the dominant component of the hormone-independent counterregulatory response to hypoglycemia in the conscious dog. Am J Physiol Endocrinol Metab 2017; 313:E273-E283. [PMID: 28512154 PMCID: PMC5625082 DOI: 10.1152/ajpendo.00099.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/04/2017] [Accepted: 05/09/2017] [Indexed: 12/26/2022]
Abstract
The contribution of hormone-independent counterregulatory signals in defense of insulin-induced hypoglycemia was determined in adrenalectomized, overnight-fasted conscious dogs receiving hepatic portal vein insulin infusions at a rate 20-fold basal. Either euglycemia was maintained (group 1) or hypoglycemia (≈45 mg/dl) was allowed to occur. There were three hypoglycemic groups: one in which hepatic autoregulation against hypoglycemia occurred in the absence of sympathetic nervous system input (group 2), one in which autoregulation occurred in the presence of norepinephrine (NE) signaling to fat and muscle (group 3), and one in which autoregulation occurred in the presence of NE signaling to fat, muscle, and liver (group 4). Average net hepatic glucose balance (NHGB) during the last hour for groups 1-4 was -0.7 ± 0.1, 0.3 ± 0.1 (P < 0.01 vs. group 1), 0.7 ± 0.1 (P = 0.01 vs. group 2), and 0.8 ± 0.1 (P = 0.7 vs. group 3) mg·kg-1·min-1, respectively. Hypoglycemia per se (group 2) increased NHGB by causing an inhibition of net hepatic glycogen synthesis. NE signaling to fat and muscle (group 3) increased NHGB further by mobilizing gluconeogenic precursors resulting in a rise in gluconeogenesis. Lowering glucose per se decreased nonhepatic glucose uptake by 8.9 mg·kg-1·min-1, and the addition of increased neural efferent signaling to muscle and fat blocked glucose uptake further by 3.2 mg·kg-1·min-1 The addition of increased neural efferent input to liver did not affect NHGB or nonhepatic glucose uptake significantly. In conclusion, even in the absence of increases in counterregulatory hormones, the body can defend itself against hypoglycemia using glucose autoregulation and increased neural efferent signaling, both of which stimulate hepatic glucose production and limit glucose utilization.
Collapse
Affiliation(s)
- Justin M Gregory
- Vanderbilt Ian Burr Division of Pediatric Endocrinology and Diabetes, Vanderbilt University School of Medicine, Nashville, Tennessee;
| | - Noelia Rivera
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Jason J Winnick
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Eric J Allen
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - E Patrick Donahue
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Marta S Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Dale S Edgerton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Phillip E Williams
- Section of Surgical Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| |
Collapse
|
9
|
Winnick JJ, Kraft G, Gregory JM, Edgerton DS, Williams P, Hajizadeh IA, Kamal MZ, Smith M, Farmer B, Scott M, Neal D, Donahue EP, Allen E, Cherrington AD. Hepatic glycogen can regulate hypoglycemic counterregulation via a liver-brain axis. J Clin Invest 2016; 126:2236-48. [PMID: 27140398 DOI: 10.1172/jci79895] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 03/10/2016] [Indexed: 11/17/2022] Open
Abstract
Liver glycogen is important for the counterregulation of hypoglycemia and is reduced in individuals with type 1 diabetes (T1D). Here, we examined the effect of varying hepatic glycogen content on the counterregulatory response to low blood sugar in dogs. During the first 4 hours of each study, hepatic glycogen was increased by augmenting hepatic glucose uptake using hyperglycemia and a low-dose intraportal fructose infusion. After hepatic glycogen levels were increased, animals underwent a 2-hour control period with no fructose infusion followed by a 2-hour hyperinsulinemic/hypoglycemic clamp. Compared with control treatment, fructose infusion caused a large increase in liver glycogen that markedly elevated the response of epinephrine and glucagon to a given hypoglycemia and increased net hepatic glucose output (NHGO). Moreover, prior denervation of the liver abolished the improved counterregulatory responses that resulted from increased liver glycogen content. When hepatic glycogen content was lowered, glucagon and NHGO responses to insulin-induced hypoglycemia were reduced. We conclude that there is a liver-brain counterregulatory axis that is responsive to liver glycogen content. It remains to be determined whether the risk of iatrogenic hypoglycemia in T1D humans could be lessened by targeting metabolic pathway(s) associated with hepatic glycogen repletion.
Collapse
|
10
|
Gregory JM, Kraft G, Scott MF, Neal DW, Farmer B, Smith MS, Hastings JR, Allen EJ, Donahue EP, Rivera N, Winnick JJ, Edgerton DS, Nishimura E, Fledelius C, Brand CL, Cherrington AD. Insulin Delivery Into the Peripheral Circulation: A Key Contributor to Hypoglycemia in Type 1 Diabetes. Diabetes 2015; 64:3439-51. [PMID: 26085570 PMCID: PMC4587648 DOI: 10.2337/db15-0071] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 06/10/2015] [Indexed: 12/25/2022]
Abstract
Hypoglycemia limits optimal glycemic control in type 1 diabetes mellitus (T1DM), making novel strategies to mitigate it desirable. We hypothesized that portal (Po) vein insulin delivery would lessen hypoglycemia. In the conscious dog, insulin was infused into the hepatic Po vein or a peripheral (Pe) vein at a rate four times of basal. In protocol 1, a full counterregulatory response was allowed, whereas in protocol 2, glucagon was fixed at basal, mimicking the diminished α-cell response to hypoglycemia seen in T1DM. In protocol 1, glucose fell faster with Pe insulin than with Po insulin, reaching 56 ± 3 vs. 70 ± 6 mg/dL (P = 0.04) at 60 min. The change in area under the curve (ΔAUC) for glucagon was similar between Pe and Po, but the peak occurred earlier in Pe. The ΔAUC for epinephrine was greater with Pe than with Po (67 ± 17 vs. 36 ± 14 ng/mL/180 min). In protocol 2, glucose also fell more rapidly than in protocol 1 and fell faster in Pe than in Po, reaching 41 ± 3 vs. 67 ± 2 mg/dL (P < 0.01) by 60 min. Without a rise in glucagon, the epinephrine responses were much larger (ΔAUC of 204 ± 22 for Pe vs. 96 ± 29 ng/mL/180 min for Po). In summary, Pe insulin delivery exacerbates hypoglycemia, particularly in the presence of a diminished glucagon response. Po vein insulin delivery, or strategies that mimic it (i.e., liver-preferential insulin analogs), should therefore lessen hypoglycemia.
Collapse
Affiliation(s)
- Justin M Gregory
- Ian M. Burr Division of Pediatric Endocrinology and Diabetes, Vanderbilt University School of Medicine, Nashville, TN
| | - Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Melanie F Scott
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Doss W Neal
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Marta S Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Jon R Hastings
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Eric J Allen
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - E Patrick Donahue
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Noelia Rivera
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Jason J Winnick
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Dale S Edgerton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | | | | | | | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| |
Collapse
|
11
|
Coate KC, Kraft G, Moore MC, Smith MS, Ramnanan C, Irimia JM, Roach PJ, Farmer B, Neal DW, Williams P, Cherrington AD. Hepatic glucose uptake and disposition during short-term high-fat vs. high-fructose feeding. Am J Physiol Endocrinol Metab 2014; 307:E151-60. [PMID: 24865981 PMCID: PMC4101635 DOI: 10.1152/ajpendo.00083.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In dogs consuming a high-fat and -fructose diet (52 and 17% of total energy, respectively) for 4 wk, hepatic glucose uptake (HGU) in response to hyperinsulinemia, hyperglycemia, and portal glucose delivery is markedly blunted with reduction in glucokinase (GK) protein and glycogen synthase (GS) activity. The present study compared the impact of selective increases in dietary fat and fructose on liver glucose metabolism. Dogs consumed weight-maintaining chow (CTR) or hypercaloric high-fat (HFA) or high-fructose (HFR) diets diet for 4 wk before undergoing clamp studies with infusion of somatostatin and intraportal insulin (3-4 times basal) and glucagon (basal). The hepatic glucose load (HGL) was doubled during the clamp using peripheral vein (Pe) glucose infusion in the first 90 min (P1) and portal vein (4 mg·kg(-1)·min(-1)) plus Pe glucose infusion during the final 90 min (P2). During P2, HGU was 2.8 ± 0.2, 1.0 ± 0.2, and 0.8 ± 0.2 mg·kg(-1)·min(-1) in CTR, HFA, and HFR, respectively (P < 0.05 for HFA and HFR vs. CTR). Compared with CTR, hepatic GK protein and catalytic activity were reduced (P < 0.05) 35 and 56%, respectively, in HFA, and 53 and 74%, respectively, in HFR. Liver glycogen concentrations were 20 and 38% lower in HFA and HFR than CTR (P < 0.05). Hepatic Akt phosphorylation was decreased (P < 0.05) in HFA (21%) but not HFR. Thus, HFR impaired hepatic GK and glycogen more than HFA, whereas HFA reduced insulin signaling more than HFR. HFA and HFR effects were not additive, suggesting that they act via the same mechanism or their effects converge at a saturable step.
Collapse
Affiliation(s)
- Katie C Coate
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Mary Courtney Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee;
| | - Marta S Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Christopher Ramnanan
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Jose M Irimia
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Peter J Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Doss W Neal
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Phil Williams
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, Tennessee; and Department of Surgery, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| |
Collapse
|
12
|
Moore MC, Smith MS, Sinha VP, Beals JM, Michael MD, Jacober SJ, Cherrington AD. Novel PEGylated basal insulin LY2605541 has a preferential hepatic effect on glucose metabolism. Diabetes 2014; 63:494-504. [PMID: 24089512 PMCID: PMC5361402 DOI: 10.2337/db13-0826] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 09/23/2013] [Indexed: 01/08/2023]
Abstract
The impact of the novel basal insulin LY2605541 (LY) on hepatic and nonhepatic glucose uptake (non-HGU) was evaluated. Conscious dogs underwent euglycemic clamps with tracer and hepatic balance measurements. Clamp period infusions were peripheral venous regular insulin (0.1 nmol ⋅ kg(-1) ⋅ h(-1) [control], n = 6) or LY (bolus [nmol/kg], continuous [nmol ⋅ kg(-1) ⋅ h(-1)]: 0.5, 0.5 [n = 6]; 0.375, 0.375 [n = 5]; 0.25, 0.25 [n = 4]), somatostatin, and glucose, as well as intraportal glucagon (basal). During the clamp, the dogs switched from net hepatic glucose output to uptake (rates reached 2.1 ± 1.2, 0.9 ± 2.1, 8.6 ± 2.3, and 6.0 ± 1.1 µmol ⋅ kg(-1) ⋅ min(-1) within 5 h in control, LY0.25, LY0.375, and LY0.5, respectively). Non-HGU in LY increased less than in control; the ratio of change from basal in non-HGU to change in net hepatic glucose balance, calculated when glucose infusion rates (GIRs) were ~20 µmol ⋅ kg(-1) ⋅ min(-1) in all groups, was higher in control (1.17 ± 0.38) versus LY0.25 (0.39 ± 0.33), LY0.375 (-0.01 ± 0.13), and LY0.5 (-0.09 ± 0.07). Likewise, the change from baseline in glucose Rd-to-Ra ratio was greatest in control (1.4 ± 0.3 vs. 0.6 ± 0.4, 0.5 ± 0.2, and 0.6 ± 0.2 in LY0.25, LY0.375, and LY0.5, respectively). In contrast to exogenously administered human insulin, LY demonstrated preferential hepatic effects, similar to endogenously secreted insulin. Therefore, the analog might reduce complications associated with current insulin therapy.
Collapse
Affiliation(s)
- Mary Courtney Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Marta S. Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Vikram P. Sinha
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - John M. Beals
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | - M. Dodson Michael
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN
| | | | - Alan D. Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| |
Collapse
|
13
|
Coate KC, Smith MS, Shiota M, Irimia JM, Roach PJ, Farmer B, Williams PE, Moore MC. Hepatic glucose metabolism in late pregnancy: normal versus high-fat and -fructose diet. Diabetes 2013; 62:753-61. [PMID: 23223020 PMCID: PMC3581200 DOI: 10.2337/db12-0875] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Net hepatic glucose uptake (NHGU) is an important contributor to postprandial glycemic control. We hypothesized that NHGU is reduced during normal pregnancy and in a pregnant diet-induced model of impaired glucose intolerance/gestational diabetes mellitus (IGT/GDM). Dogs (n = 7 per group) that were nonpregnant (N), normal pregnant (P), or pregnant with IGT/GDM (pregnant dogs fed a high-fat and -fructose diet [P-HFF]) underwent a hyperinsulinemic-hyperglycemic clamp with intraportal glucose infusion. Clamp period insulin, glucagon, and glucose concentrations and hepatic glucose loads did not differ among groups. The N dogs reached near-maximal NHGU rates within 30 min; mean ± SEM NHGU was 105 ± 9 µmol·100 g liver⁻¹·min⁻¹. The P and P-HFF dogs reached maximal NHGU in 90-120 min; their NHGU was blunted (68 ± 9 and 16 ± 17 µmol·100 g liver⁻¹·min⁻¹, respectively). Hepatic glycogen synthesis was reduced 20% in P versus N and 40% in P-HFF versus P dogs. This was associated with a reduction (>70%) in glycogen synthase activity in P-HFF versus P and increased glycogen phosphorylase (GP) activity in both P (1.7-fold greater than N) and P-HFF (1.8-fold greater than P) dogs. Thus, NHGU under conditions mimicking the postprandial state is delayed and suppressed in normal pregnancy, with concomitant reduction in glycogen storage. NHGU is further blunted in IGT/GDM. This likely contributes to postprandial hyperglycemia during pregnancy, with potential adverse outcomes for the fetus and mother.
Collapse
Affiliation(s)
- Katie C. Coate
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Marta S. Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Masakazu Shiota
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Jose M. Irimia
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Peter J. Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Phillip E. Williams
- Department of Surgery, Vanderbilt University School of Medicine, Nashville, Tennessee
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Mary Courtney Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
- Corresponding author: Mary Courtney Moore,
| |
Collapse
|
14
|
Moore MC, Coate KC, Winnick JJ, An Z, Cherrington AD. Regulation of hepatic glucose uptake and storage in vivo. Adv Nutr 2012; 3:286-94. [PMID: 22585902 PMCID: PMC3649460 DOI: 10.3945/an.112.002089] [Citation(s) in RCA: 229] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
In the postprandial state, the liver takes up and stores glucose to minimize the fluctuation of glycemia. Elevated insulin concentrations, an increase in the load of glucose reaching the liver, and the oral/enteral/portal vein route of glucose delivery (compared with the peripheral intravenous route) are factors that increase the rate of net hepatic glucose uptake (NHGU). The entry of glucose into the portal vein stimulates a portal glucose signal that not only enhances NHGU but concomitantly reduces muscle glucose uptake to ensure appropriate partitioning of a glucose load. This coordinated regulation of glucose uptake is likely neurally mediated, at least in part, because it is not observed after total hepatic denervation. Moreover, there is evidence that both the sympathetic and the nitrergic innervation of the liver exert a tonic repression of NHGU that is relieved under feeding conditions. Further, the energy sensor 5'AMP-activated protein kinase appears to be involved in regulation of NHGU and glycogen storage. Consumption of a high-fat and high-fructose diet impairs NHGU and glycogen storage in association with a reduction in glucokinase protein and activity. An understanding of the impact of nutrients themselves and the route of nutrient delivery on liver carbohydrate metabolism is fundamental to the development of therapies for impaired postprandial glucoregulation.
Collapse
Affiliation(s)
- Mary Courtney Moore
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Katie C. Coate
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN,current address: Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Jason J. Winnick
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Zhibo An
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN,current address: Department of Medicine, Division of Endocrinology, University of Cincinnati Medical Center, Cincinnati, OH
| | - Alan D. Cherrington
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| |
Collapse
|
15
|
Erejuwa OO, Sulaiman SA, Wahab MSA. Fructose might contribute to the hypoglycemic effect of honey. Molecules 2012; 17:1900-15. [PMID: 22337138 PMCID: PMC6268125 DOI: 10.3390/molecules17021900] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 02/09/2012] [Accepted: 02/09/2012] [Indexed: 12/20/2022] Open
Abstract
Honey is a natural substance with many medicinal properties, including antibacterial, hepatoprotective, hypoglycemic, antioxidant and antihypertensive effects. It reduces hyperglycemia in diabetic rats and humans. However, the mechanism(s) of its hypoglycemic effect remain(s) unknown. Honey comprises many constituents, making it difficult to ascertain which component(s) contribute(s) to its hypoglycemic effect. Nevertheless, available evidence indicates that honey consists of predominantly fructose and glucose. The objective of this review is to summarize findings which indicate that fructose exerts a hypoglycemic effect. The data show that glucose and fructose exert a synergistic effect in the gastrointestinal tract and pancreas. This synergistic effect might enhance intestinal fructose absorption and/or stimulate insulin secretion. The results indicate that fructose enhances hepatic glucose uptake and glycogen synthesis and storage via activation of hepatic glucokinase and glycogen synthase, respectively. The data also demonstrate the beneficial effects of fructose on glycemic control, glucose- and appetite-regulating hormones, body weight, food intake, oxidation of carbohydrate and energy expenditure. In view of the similarities of these effects of fructose with those of honey, the evidence may support the role of fructose in honey in mediating the hypoglycemic effect of honey.
Collapse
Affiliation(s)
- Omotayo O Erejuwa
- Department of Pharmacology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia.
| | | | | |
Collapse
|
16
|
Winnick JJ, An Z, Ramnanan CJ, Smith M, Irimia JM, Neal DW, Moore MC, Roach PJ, Cherrington AD. Hepatic glycogen supercompensation activates AMP-activated protein kinase, impairs insulin signaling, and reduces glycogen deposition in the liver. Diabetes 2011; 60:398-407. [PMID: 21270252 PMCID: PMC3028338 DOI: 10.2337/db10-0592] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The objective of this study was to determine how increasing the hepatic glycogen content would affect the liver's ability to take up and metabolize glucose. RESEARCH DESIGN AND METHODS During the first 4 h of the study, liver glycogen deposition was stimulated by intraportal fructose infusion in the presence of hyperglycemic-normoinsulinemia. This was followed by a 2-h hyperglycemic-normoinsulinemic control period, during which the fructose infusion was stopped, and a 2-h experimental period in which net hepatic glucose uptake (NHGU) and disposition (glycogen, lactate, and CO(2)) were measured in the absence of fructose but in the presence of a hyperglycemic-hyperinsulinemic challenge including portal vein glucose infusion. RESULTS Fructose infusion increased net hepatic glycogen synthesis (0.7 ± 0.5 vs. 6.4 ± 0.4 mg/kg/min; P < 0.001), causing a large difference in hepatic glycogen content (62 ± 9 vs. 100 ± 3 mg/g; P < 0.001). Hepatic glycogen supercompensation (fructose infusion group) did not alter NHGU, but it reduced the percent of NHGU directed to glycogen (79 ± 4 vs. 55 ± 6; P < 0.01) and increased the percent directed to lactate (12 ± 3 vs. 29 ± 5; P = 0.01) and oxidation (9 ± 3 vs. 16 ± 3; P = NS). This change was associated with increased AMP-activated protein kinase phosphorylation, diminished insulin signaling, and a shift in glycogenic enzyme activity toward a state discouraging glycogen accumulation. CONCLUSIONS These data indicate that increases in hepatic glycogen can generate a state of hepatic insulin resistance, which is characterized by impaired glycogen synthesis despite preserved NHGU.
Collapse
Affiliation(s)
- Jason J Winnick
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
An Z, Winnick JJ, Farmer B, Neal D, Lautz M, Irimia JM, Roach PJ, Cherrington AD. A soluble guanylate cyclase-dependent mechanism is involved in the regulation of net hepatic glucose uptake by nitric oxide in vivo. Diabetes 2010; 59:2999-3007. [PMID: 20823104 PMCID: PMC2992759 DOI: 10.2337/db10-0138] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 08/25/2010] [Indexed: 12/31/2022]
Abstract
OBJECTIVE We previously showed that elevating hepatic nitric oxide (NO) levels reduced net hepatic glucose uptake (NHGU) in the presence of portal glucose delivery, hyperglycemia, and hyperinsulinemia. The aim of the present study was to determine the role of a downstream signal, soluble guanylate cyclase (sGC), in the regulation of NHGU by NO. RESEARCH DESIGN AND METHODS Studies were performed on 42-h-fasted conscious dogs fitted with vascular catheters. At 0 min, somatostatin was given peripherally along with 4× basal insulin and basal glucagon intraportally. Glucose was delivered at a variable rate via a leg vein to double the blood glucose level and hepatic glucose load throughout the study. From 90 to 270 min, an intraportal infusion of the sGC inhibitor 1H-[1,2,4] oxadiazolo[4,3-a] quinoxalin-1-one (ODQ) was given in -sGC (n = 10) and -sGC/+NO (n = 6), whereas saline was given in saline infusion (SAL) (n = 10). The -sGC/+NO group also received intraportal SIN-1 (NO donor) to elevate hepatic NO from 180 to 270 min. RESULTS In the presence of 4× basal insulin, basal glucagon, and hyperglycemia (2× basal ), inhibition of sGC in the liver enhanced NHGU (mg/kg/min; 210-270 min) by ∼55% (2.9 ± 0.2 in SAL vs. 4.6 ± 0.5 in -sGC). Further elevating hepatic NO failed to reduce NHGU (4.5 ± 0.7 in -sGC/+NO). Net hepatic carbon retention (i.e., glycogen synthesis; mg glucose equivalents/kg/min) increased to 3.8 ± 0.2 in -sGC and 3.8 ± 0.4 in -sGC/+NO vs. 2.4 ± 0.2 in SAL (P < 0.05). CONCLUSIONS NO regulates liver glucose uptake through a sGC-dependent pathway. The latter could be a target for pharmacologic intervention to increase meal-associated hepatic glucose uptake in individuals with type 2 diabetes.
Collapse
Affiliation(s)
- Zhibo An
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee. USA.
| | | | | | | | | | | | | | | |
Collapse
|