scholarly journals Plasma calcitonin gene-related peptide is increased prior to obesity, and sensory nerve desensitization by capsaicin improves oral glucose tolerance in obese Zucker rats

2005 ◽  
Vol 153 (6) ◽  
pp. 963-969 ◽  
Author(s):  
Dorte X Gram ◽  
Anker J Hansen ◽  
Michael Wilken ◽  
Torben Elm ◽  
Ove Svendsen ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Glucose Tolerance ◽  
Sensory Nerve ◽  
Zucker Rats ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Nerve Activity ◽  
Calcitonin Gene ◽  
Obese Rats ◽  
Obese Zucker Rats

Objective: It has earlier been demonstrated that capsaicin-induced desensitization improves insulin sensitivity in normal rats. However, whether increased capsaicin-sensitive nerve activity precedes the onset of insulin resistance in diet-induced obesity – and therefore might be involved in the pathophysiology – is not known. Further, it is of relevance to investigate whether capsaicin desensitization improves glycaemic control even in obese individuals and we therefore chose the obese Zucker rats to test this. Design and methods: Plasma levels of calcitonin gene-related peptide (CGRP; a marker of sensory nerve activity) was assessed in 8-week-old Zucker rats. To investigate whether capsaicin desensitization (100 mg/kg at 9 weeks of age) would also ameliorate glycaemia in this non-diabetic model, we assessed oral glucose tolerance at 7 weeks after capsaicin. Results: It was found that plasma CGRP levels were elevated in obese Zucker rats prior to the onset of obesity (16.1±3.4 pmol/l in pre-obese Zucker rats vs 6.9±1.1 pmol/l in lean littermates; P = 0.015) despite similar body weights. Furthermore, capsaicin desensitization reduced both fasting blood glucose (4.3±0.2 mmol/l vs 5.1±0.2 mmol/l in controls; P = 0.050) as well as the mean blood glucose level during an oral glucose tolerance test (OGTT) (6.8±0.3 mmol/l vs 8.6±0.5 mmol/l in control obese rats; P = 0.024) whereas the plasma insulin levels during the OGTT were unchanged. However this did not lead to an improvement in insulin resistance or to a reduction of tissue triglyceride accumulation in muscle or liver. Conclusion: We concluded that capsaicin-induced sensory nerve desensitization improves glucose tolerance in Zucker rats. Since, in this study, plasma CGRP levels, a marker of sensory nerve activity, were increased in the pre-obese rats, our data support the hypothesis that increased activity of sensory nerves precedes the development of obesity and insulin resistance in Zucker rats.

Sensory nerve inactivation by resiniferatoxin improves insulin sensitivity in male obese Zucker rats

2005 ◽  
Vol 288 (6) ◽  
pp. E1137-E1145 ◽  
Author(s):  
Sophia G. Moesgaard ◽  
Christian L. Brand ◽  
Jeppe Sturis ◽  
Bo Ahrén ◽  
Michael Wilken ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Insulin Sensitivity ◽  
Glucose Tolerance ◽  
Sensory Nerve ◽  
Sensory Nerves ◽  
Zucker Rats ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Obese Zucker Rat ◽  
Obese Zucker Rats

Recent studies have suggested that sensory nerves may influence insulin secretion and action. The present study investigated the effects of resiniferatoxin (RTX) inactivation of sensory nerves (desensitization) on oral glucose tolerance, insulin secretion and whole body insulin sensitivity in the glucose intolerant, hyperinsulinemic, and insulin-resistant obese Zucker rat. After RTX treatment (0.05 mg/kg RTX sc given at ages 8, 10, and 12 wk), fasting plasma insulin was reduced ( P < 0.0005), and oral glucose tolerance was improved ( P < 0.005). Pancreas perfusion showed that baseline insulin secretion (7 mM glucose) was lower in RTX-treated rats ( P = 0.01). Insulin secretory responsiveness to 20 mM glucose was enhanced in the perfused pancreas of RTX-treated rats ( P < 0.005) but unaffected in stimulated, isolated pancreatic islets. At the peak of spontaneous insulin resistance in the obese Zucker rat, insulin sensitivity was substantially improved after RTX treatment, as evidenced by higher glucose infusion rates (GIR) required to maintain euglycemia during a hyperinsulinemic euglycemic (5 mU·kg−1·min−1) clamp (GIR60–120min: 5.97 ± 0.62 vs. 11.65 ± 0.83 mg·kg−1·min−1 in RTX-treated rats, P = 0.003). In conclusion, RTX treatment and, hence, sensory nerve desensitization of adult male obese Zucker rats improved oral glucose tolerance by enhancing insulin secretion, and, in particular, by improving insulin sensitivity.

Abnormal oral glucose tolerance in genetically obese (fa/fa) rats

1985 ◽  
Vol 248 (5) ◽  
pp. E500-E506 ◽  
Author(s):  
E. Ionescu ◽  
J. F. Sauter ◽  
B. Jeanrenaud
Keyword(s):  
Insulin Resistance ◽  
Glucose Tolerance ◽  
Beta Cell ◽  
Oral Glucose ◽  
Base Line ◽  
Oral Glucose Tolerance ◽  
Intravenous Glucose ◽  
Insulin Levels ◽  
Glucose Ingestion ◽  
Obese Rats

The effect of intravenous glucose or tolbutamide administration on plasma glucose and insulin levels was compared with that following spontaneous ingestion of glucose in freely moving 6- to 7-wk- and 13- to 14-wk-old lean and obese (fa/fa) rats. Irrespective of age, the obese rats had a normal blood glucose tolerance when glucose or tolbutamide load was given intravenously, whereas the glucose ingestion [oral glucose tolerance test (OGTT) caused a marked glucose intolerance that became more pronounced with the duration of the syndrome. This suggests that factors other than insulin resistance could play a role in the occurrence of abnormal OGTT in obese rats. When blood insulin levels were expressed as percent change over base line and when compared with age-matched normal rats, the 6- to 7-wk obese rats showed a normal and even higher beta-cell responsiveness to intravenous or oral glucose as well as to tolbutamide. In contrast, the 13- to 14-wk obese rats presented a decreased beta-cell responsiveness to all such stimuli. Thus the beta-cell function of obese rats worsens with time. Inasmuch as 13- to 14-wk-old obese fa/fa rats have insulin resistance, high basal glycemia, and abnormal oral glucose tolerance, they can be viewed as a potential model of type II diabetes.

Tesaglitazar, a dual PPARα/γ agonist, ameliorates glucose and lipid intolerance in obese Zucker rats

2005 ◽  
Vol 289 (4) ◽  
pp. R938-R946 ◽  
Author(s):  
Nicholas D. Oakes ◽  
Pia Thalén ◽  
Therese Hultstrand ◽  
Severina Jacinto ◽  
Germán Camejo ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Glucose Tolerance ◽  
Zucker Rats ◽  
Oral Glucose ◽  
Therapeutic Effects ◽  
The Metabolic Syndrome ◽  
Increased Risk ◽  
Mass Load ◽  
Obese Zucker Rats

Insulin resistance, impaired glucose tolerance, high circulating levels of free fatty acids (FFA), and postprandial hyperlipidemia are associated with the metabolic syndrome, which has been linked to increased risk of cardiovascular disease. We studied the metabolic responses to an oral glucose/triglyceride (TG) (1.7/2.0 g/kg lean body mass) load in three groups of conscious 7-h fasted Zucker rats: lean healthy controls, obese insulin-resistant/dyslipidemic controls, and obese rats treated with the dual peroxisome proliferator-activated receptor α/γ agonist, tesaglitazar, 3 μmol·kg−1·day−1 for 4 wk. Untreated obese Zucker rats displayed marked insulin resistance, as well as glucose and lipid intolerance in response to the glucose/TG load. The 2-h postload area under the curve values were greater for glucose (+19%), insulin (+849%), FFA (+53%), and TG (+413%) compared with untreated lean controls. Treatment with tesaglitazar lowered fasting plasma glucose, improved glucose tolerance, substantially reduced fasting and postload insulin levels, and markedly lowered fasting TG and improved lipid tolerance. Fasting FFA were not affected, but postprandial FFA suppression was restored to levels seen in lean controls. Mechanisms of tesaglitazar-induced lowering of plasma TG were studied separately using the Triton WR1339 method. In anesthetized, 5-h fasted, obese Zucker rats, tesaglitazar reduced hepatic TG secretion by 47%, increased plasma TG clearance by 490%, and reduced very low-density lipoprotein (VLDL) apolipoprotein CIII content by 86%, compared with obese controls. In conclusion, the glucose/lipid tolerance test in obese Zucker rats appears to be a useful model of the metabolic syndrome that can be used to evaluate therapeutic effects on impaired postprandial glucose and lipid metabolism. The present work demonstrates that tesaglitazar ameliorates these abnormalities and enhances insulin sensitivity in this animal model.

Insulin resistance of obese Zucker rats exercise trained at two different intensities

1991 ◽  
Vol 261 (5) ◽  
pp. E613-E619 ◽  
Author(s):  
M. Y. Cortez ◽  
C. E. Torgan ◽  
J. T. Brozinick ◽  
J. L. Ivy
Keyword(s):  
Glucose Tolerance ◽  
Glucose Uptake ◽  
Citrate Synthase ◽  
Exercise Group ◽  
Zucker Rats ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Equal Work ◽  
Obese Zucker Rats ◽  
Fast Twitch

The effect of exercise intensity on oral glucose tolerance and hindlimb glucose uptake and transport was studied in 26 female obese Zucker rats after a treadmill training program. The rats were randomly assigned to either a low-intensity (LI) or high-intensity (HI) exercise group, with equal work being performed by the two groups. A third group of rats served as sedentary controls (SED). The trained rats demonstrated a significant improvement in oral glucose tolerance while maintaining significantly lower plasma insulin concentrations when compared with the SED rats. However, no significant differences in plasma glucose or insulin concentrations were observed between the LI and HI exercise-trained groups. During hindlimb perfusion (500 microU/ml insulin, 8 mM glucose), the rate of muscle glucose uptake for the HI rats (13.5 +/- 0.8 mumol.h-1.g-1) was significantly faster than that of the LI rats (11.4 +/- 0.8 mumol.h-1.g-1), which was significantly faster than that of the SED rats (8.3 +/- 0.6 mumol.h-1.g-1). The rates of 3-O-methyl-D-glucose (3-MG) transport were substantially greater in the fast-twitch red fibers of the HI (10.11 +/- 0.49 mumol.h-1.g-1) and LI (9.08 +/- 0.46 mumol.h-1.g-1) rats when compared with those of the SED rats (6.15 +/- 0.41 mumol.h-1.g-1). However, only the HI training resulted in a significant increase in the 3-MG transport of the fast-twitch white fibers (HI, 2.37 +/- 0.27; LI, 1.48 +/- 0.11; SED, 1.31 +/- 0.15 mumol.h-1.g-1). Only muscles with an increased citrate synthase activity demonstrated an improved insulin-stimulated glucose transport.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Improved functional vasodilation in obese Zucker rats following exercise training

2011 ◽  
Vol 301 (3) ◽  
pp. H1090-H1096 ◽  
Author(s):  
Mohamad Sebai ◽  
Silu Lu ◽  
Lusha Xiang ◽  
Robert L. Hester
Keyword(s):  
Insulin Resistance ◽  
Exercise Training ◽  
Glucose Tolerance ◽  
Tolerance Test ◽  
Zucker Rats ◽  
Oral Glucose ◽  
Global Effect ◽  
Thromboxane Receptor ◽  
Improve Insulin Resistance ◽  
Obese Zucker Rats

Obese individuals exhibit impaired functional vasodilation and exercise performance. We have demonstrated in obese Zucker rats (OZ), a model of morbid obesity, that insulin resistance impairs functional vasodilation via an increased thromboxane receptor (TP)-mediated vasoconstriction. Chronic treadmill exercise training improves functional vasodilation in the spinotrapezius muscle of the OZ, but the mechanisms responsible for the improvement in functional vasodilation are not clear. Based on evidence that exercise training improves insulin resistance, we hypothesized that, in the OZ, exercise training increases functional vasodilation and exercise capability due to decreases TP-mediated vasoconstriction associated with improved insulin sensitivity. Six-week-old lean Zucker rats (LZ) and OZ were exercised on a treadmill (24 m/min, 30 min/day, 5 days/wk) for 6 wk. An oral glucose tolerance test was performed at the end of the training period. We measured functional vasodilation in both exercise trained (spinotrapezius) and nonexercise trained (cremaster) muscles to determine whether the improved functional vasodilation following exercise training in OZ is due to a systemic improved insulin resistance. Compared with LZ, the sedentary OZ exhibited impairments in glucose tolerance and functional vasodilation in both muscles. The TP antagonist SQ-29548 improved the vasodilator responses in the sedentary OZ with no effect in the LZ. Exercising training of the LZ increased the functional vasodilation in spinotrapezius muscle, with no effect in the cremaster muscle. Exercising training of the OZ improved glucose tolerance, along with increased functional vasodilation, in both the spinotrapezius and cremaster muscles. SQ-29548 treatment had no effect on the vasodilator responses in either cremaster or spinotrapezius muscles of the exercise-trained OZ. These results suggest that, in the OZ, there is a global effect of exercising training to improve insulin resistance and increase functional vasodilation via a decreased TP-mediated vasoconstriction.

scholarly journals QOL-43. ENDOCRINE AND METABOLIC CHANGES IN CHILDREN TREATED FOR MEDULLOBLASTOMA

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii439-iii439
Author(s):  
Alexey Kalinin ◽  
Natalia Strebkova ◽  
Olga Zheludkova
Keyword(s):  
Insulin Resistance ◽  
Body Composition ◽  
Glucose Tolerance ◽  
Oral Glucose Tolerance Test ◽  
Impaired Glucose Tolerance ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Hormone Deficiency ◽  
Oral Glucose ◽  
Oral Glucose Tolerance

Abstract We examined 63 patients (40 males/23 females) after complex treatment of medulloblastoma. Patients had a median age (range) of 11.3 (5.5 ÷ 17.9) years. The median time after the end of treatment was 3.7 (1.5 ÷ 11.6) years. Endocrine disorders were detected with the following frequency: growth hormone deficiency - 98.41% (62 of 63 patients), thyroid hormone deficiency – 69.8% (44/63), adrenal hormone deficiency - 17.4% (11/63). Three cases (4.7%) of premature sexual development were also detected. Lipids levels, beta-cell function and insulin resistance (IR) during 2-h oral glucose tolerance test were evaluated. A mono frequent bioelectrical impedanciometer was used to measure body composition. Overweight (SDS BMI&gt; 1) was observed only in 16 patients (3 girls and 13 boys), obesity (SDS BMI&gt; 2) in 1 boy. Dyslipidemia was found in 34 patients (54%). All patients underwent oral glucose tolerance test. Insulin resistance (ISI Matsuda &lt;2.5 and/or HOMA-IR&gt; 3.2) was detected in 7 patients (11/1%), impaired glucose tolerance (120 min glucose ≥7.8 mmol / l) was observed in 2 patients with IR and in 2 patients without IR. At the same time, IR and impaired glucose tolerance were encountered in only 5 children with overweight and no one with obesity. All patients with impaired glucose tolerance had normal values of fasting glucose (4.3 ÷ 5.04 mmol / l) and HbA1c (4.8 ÷ 5.8%). A bioelectrical impedanciometer was used to measure body composition in 49 cases, the percentage of adipose tissue was increased in 14 patients (28%) with normal BMI.

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