scholarly journals Glucose Transporter Expression and Regulation Following a Fast in the Ruby-throated Hummingbird, Archilochus colubris

2020 ◽  
Author(s):  
Raafay S. Ali ◽  
Morag F. Dick ◽  
Saad Muhammad ◽  
Dylan Sarver ◽  
G. William Wong ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Glucose Transporter ◽  
Flight Muscle ◽  
Sugar Transport ◽  
Uptake Capacity ◽  
High Blood Glucose ◽  
Glucose Levels ◽  
High Fructose ◽  
Sugar Regulation ◽  
Ad Libitum

AbstractHummingbirds subsist almost exclusively on nectar sugar and face extreme challenges blood sugar regulation. Transmembrane sugar transport is mediated by facilitative glucose transporters (GLUTs) and the capacity for sugar transport is dependent on both the activity of GLUTs and their localisation to the plasma membrane (PM). In this study, we determined the relative protein abundance in whole-tissue (WT) homogenates and PM fractions via immunoblot using custom antibodies for GLUT1, GLUT2, GLUT3, and GLUT5 in flight muscle, heart, and, liver of ruby-throated hummingbirds (Archilochus colubris). GLUTs examined were detected in nearly all tissues tested. Hepatic GLUT1 was minimally present in WT homogenates and absent in PM fractions. GLUT5 was expressed in hummingbird flight muscles at levels comparable to that of their liver, consistent with the hypothesised uniquely high fructose-uptake and oxidation capacity of this tissue. To assess GLUT regulation, we fed ruby-throated hummingbirds 1M sucrose ad libitum for 24 hours followed by either 1 hour of fasting or continued ad libitum feeding until sampling. We measured relative GLUT abundance and concentrations of circulating sugars. Blood fructose concentration in fasted hummingbirds declined from ∼5mM to ∼0.18mM, while fructose-transporting PM GLUT2 and PM GLUT5 did not change in abundance. Blood glucose concentrations remained elevated in both fed and fasted hummingbirds, at ∼30mM, while glucose-transporting PM GLUT1 and PM GLUT3 in the flight muscle and liver, respectively, declined in fasted birds. Our results suggest that glucose uptake capacity is dynamically reduced in response to fasting, allowing for maintenance of elevated blood glucose levels, while fructose uptake capacity remains constitutively elevated promoting depletion of blood total fructose within the first hour of a fast.Summary statementHummingbird ingest nectar rich in glucose and fructose. When fasted, tissue capacity for circulating glucose import declines while remaining elevated for fructose. This may underlie maintenance of high blood glucose and rapid depletion of blood fructose.

scholarly journals Glucose transporter expression and regulation following a fast in the ruby-throated hummingbird, Archilochus colubris

2020 ◽  
Vol 223 (20) ◽  
pp. jeb229989 ◽  
Author(s):  
Raafay S. Ali ◽  
Morag F. Dick ◽  
Saad Muhammad ◽  
Dylan Sarver ◽  
Lily Hou ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Glucose Transporter ◽  
Flight Muscle ◽  
Sugar Transport ◽  
Uptake Capacity ◽  
Glucose Levels ◽  
High Fructose ◽  
Sugar Regulation ◽  
Tissue Homogenates ◽  
Flight Muscles

ABSTRACTHummingbirds, subsisting almost exclusively on nectar sugar, face extreme challenges to blood sugar regulation. The capacity for transmembrane sugar transport is mediated by the activity of facilitative glucose transporters (GLUTs) and their localisation to the plasma membrane (PM). In this study, we determined the relative protein abundance of GLUT1, GLUT2, GLUT3 and GLUT5 via immunoblot using custom-designed antibodies in whole-tissue homogenates and PM fractions of flight muscle, heart and liver of ruby-throated hummingbirds (Archilochus colubris). The GLUTs examined were detected in nearly all tissues tested. Hepatic GLUT1 was minimally present in whole-tissue homogenates and absent win PM fractions. GLUT5 was expressed in flight muscles at levels comparable to those of the liver, consistent with the hypothesised uniquely high fructose uptake and oxidation capacity of hummingbird flight muscles. To assess GLUT regulation, we fed ruby-throated hummingbirds 1 mol l−1 sucrose ad libitum for 24 h followed by either 1 h of fasting or continued feeding until sampling. We measured relative GLUT abundance and concentration of circulating sugars. Blood fructose concentration in fasted hummingbirds declined (∼5 mmol l−1 to ∼0.18 mmol l−1), while fructose-transporting GLUT2 and GLUT5 abundance did not change in PM fractions. Blood glucose concentrations remained elevated in fed and fasted hummingbirds (∼30 mmol l−1), while glucose-transporting GLUT1 and GLUT3 in flight muscle and liver PM fractions, respectively, declined in fasted birds. Our results suggest that glucose uptake capacity is dynamically reduced in response to fasting, allowing for maintenance of elevated blood glucose levels, while fructose uptake capacity remains constitutively elevated promoting depletion of blood total fructose within the first hour of a fast.

Effect of Addition of WZB117 as an Inhibitor of Glucose Transporter 1 for Venous Blood Glucose Determination

2020 ◽  
Author(s):  
Lei Zhang ◽  
Yaqiong Ran ◽  
Yan Zhu ◽  
Qianna Zhen
Keyword(s):  
Blood Glucose ◽  
Glucose Level ◽  
Glucose Transporter ◽  
Venous Blood ◽  
Sugar Transport ◽  
Glucose Transporter 1 ◽  
Glucose Determination ◽  
Glucose Levels ◽  
Significant Difference ◽  
Blood Glucose Determination

Abstract Objective Sodium fluoride (NaF) has been applied to inhibit glycolysis in venous specimens for decades. However, it has had little effect on the rate of glycolysis in the first 1 to 2 hours, resulting in a decrease of glucose, so a more efficient method is needed. Recently, we discovered that WZB117, a specific Glut1 inhibitor, restricts glycolysis by inhibiting the passive sugar transport of human red blood cells and cancer cells. The purpose of this study was to evaluate the results of intravenous blood glucose determination after the addition of WZB117. Methods Venous specimens from 40 pairs of healthy volunteers were collected for several days and placed in tubes containing NaF plus EDTA-disodium (Na2) without WZB117 (the A group); citric acid, trisodium citrate, and EDTA-Na2 without WZB117 (B group); and NaF plus EDTA-Na2 with WZB117 (C group). The glucose concentration was measured after venipuncture and compared with test tubes treated for 1 hour, 2 hours, and 3 hours before centrifugation. Glucose level was determined by the hexokinase method. The paired t-test was used to examine differences in glucose values at baseline and at different time points. The number of misdiagnoses and the misdiagnosis rate were calculated at 2 diagnostic stages: high risk of diabetes (glucose level of 6.1 mmol/L) and diagnosis of diabetes (glucose level of 7.0 mmol/L). Results Glucose levels decreased by 1.0% at 1 hour and by 2.1% at 3 hours in the C group tubes and simultaneously decreased by 1.7% at 1 hour and by 2.5% at 3 hours in the B group tubes. In contrast, glucose levels decreased by 4.1% at 1 hour and by 6.3% at 3 hours in the A group tubes. There was a statistically significant difference in glucose levels measured in the A group tubes and B group tubes at 1 hour, 2 hours, and 3 hours. The misdiagnosis rate of clinical diagnosis in diabetes was highest in the A group tubes (7.0‰ at 1 hour, 0.1‰ at 3 hours at 7.0 mmol/L point; 14.6‰ at 1 hour, 0.4‰ at 3 hours at 6.1 mmol/L point) and lowest in the C group tubes (2.95‰ at 1 hour, 0‰ at 3 hours at 7.0 mmol/L point; 4.8‰ at 1 hour, 0.1‰ at 3 hours at 6.1 mmol/L point). Conclusion The tube addition of WZB117 is more suitable for minimizing glycolysis and has no effect on glucose levels even if specimens are left uncentrifuged for up to 3 hours.

High Blood Glucose Levels Affect Auditory Brainstem Responses after Acoustic Overexposure in Rats

2021 ◽  
pp. 1-8
Author(s):  
Jae-Hun Lee ◽  
Sang Hee Ji ◽  
Jae Yun Jung ◽  
Min Young Lee ◽  
Chi-Kyou Lee
Keyword(s):  
Blood Glucose ◽  
Hearing Threshold ◽  
Auditory Brainstem ◽  
Diabetic Rats ◽  
Control Groups ◽  
High Blood Glucose ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Hearing Function ◽  
Brainstem Response

Introduction: Diabetes mellitus (DM) is a systemic disease characterized by hyperglycemia and several pathological changes. DM-related hearing dysfunctions are associated with histological changes. Here, we explore hearing function and synaptic changes in the inner hair cells (IHCs) of rats with streptozotocin (STZ)-induced diabetes. Methods: STZ was injected to trigger diabetes. Rats with DM were exposed to narrow-band noise (105 dB SPL) for 2 h, and hearing function was analyzed 1, 3, 7, and 14 days later. Both the hearing threshold and the peak 1 amplitude of the tone auditory brainstem response were assessed. After the last functional test, animals were sacrificed for histological evaluation. Results: We found no changes in the baseline hearing threshold; however, the peak 1 amplitude at the low frequency (4 kHz) was significantly higher in both DM groups than in the control groups. The hearing threshold had not fully recovered at 14 days after diabetic rats were exposed to noise. The peak 1 amplitude at the higher frequencies (16 and 32 kHz) was significantly larger in both DM groups than in the control groups. The histological analysis revealed that the long-term DM group had significantly more synapses in the 16 kHz region than the other groups. Conclusions: We found that high blood glucose levels increased peak 1 amplitudes without changing the hearing threshold. Diabetic rats were less resilient in threshold changes and were less vulnerable to peak 1 amplitude and synaptic damage than control animals.

scholarly journals A Nutraceutical Combination of Cinnamon, Purple Onion, and Tea Linked with Key Enzymes on Treatment of Type 2 Diabetes

2021 ◽  
Author(s):  
Lebin Weng ◽  
Ting-Hsu Chen ◽  
Liyue Huang ◽  
Dong Lai ◽  
Yaw-Syan Fu ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Maximal Response ◽  
Oral Glucose ◽  
Postprandial Plasma Glucose ◽  
Glucose Levels ◽  
High Fructose ◽  
Tea Extract

Abstract Background: Diabetes mellitus (DM) is concomitant with significant morbidity and mortality and its prevalence is accumulative worldwide. The conventional antidiabetic agents are known to mitigate the symptoms of diabetes; however, they may also cause adverse effects. This study explores the efficacy of polyherbal dietary supplement cinnamon, purple onion, and tea on the mediation of postprandial hyperglycemia for in the search of combinations with a maximal response. Materials and methods: A starch solution (3 g/kg Bwt) of oral starch tolerance test (OSTT) and glucose solution (4 g/kg Bwt) of oral glucose tolerance test (OGTT) with and without cinnamon, purple onion, tea extract (15 mg/kg Bwt), and mixture (each 5 mg/kg Bwt, 1:1:1), metformin (14 mg/kg Bwt), or acarbose (50 mg/kg Bwt) was administered to high fat plus high fructose-induced diabetic mice after an overnight fast. Postprandial plasma glucose levels were measured and incremental areas under the response curve were calculated. Results: Compared with acarbose, the mixture of extracts (purple onion, cinnamon, and tea) indicated decreasing blood glucose in OSTT. In OGTT, the mixture of extracts showed greater efficacy for hypoglycemia when compared with metformin. The molecular docking of α-Amylase, α-Glucosidase, and AMPK confirmed the putatively acting molecules from the extracts of purple onion, cinnamon, and tea. Conclusions: Overall, this investigation evidenced a beneficial mediation for the progression of lowering blood glucose with a combinatory extract of cinnamon, dietary onion, and tea, implicating their prospective as nutraceuticals that might ameliorate hyperglycemia in diabetes.

Influence of glucose levels on clinical outcome after mechanical thrombectomy for large-vessel occlusion: a systematic review and meta-analysis

2021 ◽  
pp. neurintsurg-2021-017771
Author(s):  
Carlos Perez-Vega ◽  
Ricardo A Domingo ◽  
Shashwat Tripathi ◽  
Andres Ramos-Fresnedo ◽  
Samir Kashyap ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Clinical Outcome ◽  
Mechanical Thrombectomy ◽  
Meta Analysis ◽  
Large Vessel Occlusion ◽  
Vessel Occlusion ◽  
High Blood Glucose ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Increased Risk

Mechanical thrombectomy (MT) represents the mainstay of treatment for patients with acute ischemic stroke due to large-vessel occlusion (LVO). Intravenous thrombolysis has been associated with worse clinical outcome in patients presenting with high blood glucose levels at admission; to date the true effect of hyperglycemia in the setting of MT has not been fully elucidated. In this meta-analysis, we analyzed the influence of high blood glucose levels at admission on clinical outcome after MT. Ovid EMBASE, PubMed, Scopus, and Cochrane Library databases were searched from their dates of inception up to March 2021. An initial search identified 2118 articles representing 1235 unique studies. After applying selection criteria, three prospective and five retrospective studies were analyzed, yielding a pooled cohort of 5861 patients (2041 who presented with hyperglycemia, and 3820 who presented with normal blood glucose levels). Patients in the hyperglycemia group were less likely to have a modified Ranking Scale (mRS) score <3 (risk ratio (RR): 0.65; 95% CI 0.59 to 0.72; p<0.0001; I2=13%), and had an increased risk of symptomatic intracranial hemorrhage (sICH) (RR: 2.07; 95% CI 1.65 to 2.60; p<0.0001; I2=0%) and mortality (RR: 1.73; 95% CI 1.57 to 1.91; p<0.0001; I2=0%). Patients who present with hyperglycemia and undergo MT for treatment of LVO have an increased risk of unfavorable clinical outcome, sICH, and mortality. Glucose levels at admission appear to be a prognostic factor in this subset of patients. Further studies should focus on evaluating control of the glucose level at admission as a modifiable risk factor in patients undergoing MT for LVO.

Sitagliptin: A DPP-4 Inhibitor for the Treatment of Type 2 Diabetes Mellitus

2011 ◽  
Vol 3 ◽  
pp. CMT.S6227 ◽  
Author(s):  
Kathryn MS Johnson ◽  
Kathleen Schurr
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Blood Glucose ◽  
Diabetes Therapy ◽  
High Blood Glucose ◽  
Adverse Side Effects ◽  
Glucose Levels ◽  
Blood Glucose Levels

Type 2 diabetes mellitus (T2DM) has become an epidemic, with worldwide projections indicating that more than 336 million people will be afflicted with the disease by 2030. T2DM is characterized by inappropriately high blood glucose levels due to a deficiency in insulin secretion, action, or both. Despite the horrific complications that occur with chronic elevations of blood glucose levels, less than half of those with T2DM do not maintain proper glycemic control. Sitagliptin (Januvia, Merck and Co., Whitehouse Station, New Jersey) is a novel diabetes therapy approved for use in the U.S. and Europe. This small molecule inhibits the activity of DPP-4, a peptidase that degrades the glucoregulatory hormone GLP-1. Sitagliptin increases glucoregulation in individuals with T2DM both as a monotherapy and in combination with other antihyperglycemic drugs, with a low risk of adverse side effects.

Liver glycogen content decreases during meals in rats

1982 ◽  
Vol 243 (3) ◽  
pp. R450-R453
Author(s):  
W. Langhans ◽  
N. Geary ◽  
E. Scharrer
Keyword(s):  
Blood Glucose ◽  
Glycogen Content ◽  
Liver Glycogen ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Liver Glycogen Content ◽  
Ad Libitum ◽  
Portal Veins ◽  
Hepatic Portal

The effects of feeding on liver glycogen content and blood glucose in the hepatic and hepatic portal veins were investigated in rats. Liver glycogen content decreased about 25% during meals both in rats refed after 12 h food deprivation (23 +/- 1 to 17 +/- 1 mg glycogen/g liver) and in ad libitum-fed rats taking fully spontaneous meals (44 +/- 2 to 32 +/- 2 mg/g). Liver glycogen began to increase within 30 min after meals in ad libitum-fed rats. Hepatic vein blood glucose levels at meal onset (118 +/- 4 mg/dl in the food-deprived rats, 127 +/- 4 in ad libitum-fed rats) and at meal end (155 +/- 3 and 166 +/- 5 mg/dl, respectively) were similar in the two groups. Portal vein blood glucose increased during meals in the previously food-deprived rats (83 +/- 4 to 116 +/- 6 mg/dl) but not in the ad libitum-fed rats (127 +/- 5 to 132 +/- 3 mg/dl). Mechanisms that may elicit prandial glycogenolysis and the possible role of this effect in the production of meal ending satiety are discussed.

scholarly journals High activity enables life on a high-sugar diet: blood glucose regulation in nectar-feeding bats

2011 ◽  
Vol 278 (1724) ◽  
pp. 3490-3496 ◽  
Author(s):  
Detlev H. Kelm ◽  
Ralph Simon ◽  
Doreen Kuhlow ◽  
Christian C. Voigt ◽  
Michael Ristow
Keyword(s):  
Blood Glucose ◽  
High Activity ◽  
Flight Time ◽  
Floral Nectar ◽  
High Blood Glucose ◽  
Natural Diet ◽  
Glucose Levels ◽  
Nectar Feeding ◽  
Blood Glucose Levels ◽  
Normal Feeding

High blood glucose levels caused by excessive sugar consumption are detrimental to mammalian health and life expectancy. Despite consuming vast quantities of sugar-rich floral nectar, nectar-feeding bats are long-lived, provoking the question of how they regulate blood glucose. We investigated blood glucose levels in nectar-feeding bats ( Glossophaga soricina ) in experiments in which we varied the amount of dietary sugar or flight time. Blood glucose levels increased with the quantity of glucose ingested and exceeded 25 mmol l −1 blood in resting bats, which is among the highest values ever recorded in mammals fed sugar quantities similar to their natural diet. During normal feeding, blood glucose values decreased with increasing flight time, but only fell to expected values when bats spent 75 per cent of their time airborne. Either nectar-feeding bats have evolved mechanisms to avoid negative health effects of hyperglycaemia, or high activity is key to balancing blood glucose levels during foraging. We suggest that the coevolutionary specialization of bats towards a nectar diet was supported by the high activity and elevated metabolic rates of these bats. High activity may have conferred benefits to the bats in terms of behavioural interactions and foraging success, and is simultaneously likely to have increased their efficiency as plant pollinators.

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