Glucose utilization and insulin action in adult rats submitted to prolonged food restriction

1992 ◽  
Vol 263 (1) ◽  
pp. E1-E7 ◽  
Author(s):  
F. Escriva ◽  
C. Rodriguez ◽  
J. Cacho ◽  
C. Alvarez ◽  
B. Portha ◽  
...  

Glucose tolerance and insulin effects on glucose production and utilization by various tissues were studied in 70-day-old anesthetized rats submitted to food restriction from the fetal stage. Basal and glucose-induced plasma insulin levels were reduced in food-restricted rats without alterations in glucose tolerance. Insulin action was quantified by using the euglycemic-hyperinsulinemic clamp technique. Glucose turnover rates were measured by using D-[6-3H]glucose. Exogenous insulin failed to decrease glucose production in food-restricted rats. Weight-related whole body glucose utilization was higher in restricted rats than in controls both in the basal (21.9 +/- 0.7 vs. 9.4 +/- 0.6 mg.min-1.kg-1) and hyperinsulinemic states (37.5 +/- 1.1 vs. 14.0 +/- 1.2 mg.min-1.kg-1). Local glucose utilization by peripheral tissues was estimated by a 2-deoxy-D-[1-3H]glucose technique. In both basal and hyperinsulinemic conditions glucose utilization was increased in various adipose and muscle tissues of the food-restricted rats as compared with the controls. Thus we conclude that food restriction leads to an increase in the insulin-mediated glucose uptake by various peripheral tissues and to insulin resistance in the liver.

1986 ◽  
Vol 251 (5) ◽  
pp. E537-E541 ◽  
Author(s):  
A. F. Burnol ◽  
A. Leturque ◽  
P. Ferre ◽  
J. Kande ◽  
J. Girard

In 12-day lactating rats blood glucose and plasma insulin were decreased by, respectively, 20 and 35% when compared with nonlactating rats, despite a 25% increase of their glucose turnover rate. Then, by using the euglycemic hyperinsulinemic clamp technique, dose-response curves for the effects of insulin on glucose production and utilization in lactating and nonlactating rats were performed. Glucose production rate was totally suppressed at 250 microU/ml of insulin in lactating rats and for plasma insulin concentrations higher than 500 microU/ml in nonlactating rats. Plasma insulin level inducing half-maximal inhibition of glucose production was decreased by 60% during lactation. The maximal effect of insulin on glucose utilization rate and glucose metabolic clearance rate was, respectively, increased 1.5- and 2.4-fold during lactation and was obtained for plasma insulin concentrations lower in lactating than in nonlactating rats (250 vs. 500 microU/ml). Insulin concentrations inducing half-maximal stimulation of glucose utilization and glucose metabolic clearance were decreased by 50% during lactation. In conclusion, this study has shown that insulin sensitivity and responsiveness of liver and peripheral tissues are improved at peak lactation in the rat.


1996 ◽  
Vol 270 (6) ◽  
pp. E946-E954 ◽  
Author(s):  
M. J. Holness

Glucoregulation and insulin action were examined in adult female progeny of dams fed an 8% protein diet during gestation and lactation. Progeny were provided with standard (20% protein) diet at weaning (24 days), at which time body weight was reduced by 21%. Basal (postabsorptive) endogenous glucose production (Ra) and glucose utilization by oxidative muscles was decreased in offspring that had experienced early growth retardation. The glucose disappearance rate after intravenous glucose and the glucose infusion rate required to maintain euglycemia during insulin infusion were both increased (by 35 and 24%, respectively) by early growth retardation. Insulin secretion was unimpaired. During euglycemic-hyperinsulinemic clamp, Ra was suppressed further, and there was a twofold greater increment in the stimulation of whole body glucose clearance rate in the offspring that experienced early growth retardation. Insulin-stimulated glucose utilization by peripheral tissues was unaffected.


1985 ◽  
Vol 54 (2) ◽  
pp. 449-458 ◽  
Author(s):  
A. N. Janes ◽  
T. E. C. Weekes ◽  
D. G. Armstrong

1. Sheep fitted with re-entrant canulas in the proximal duodenum and terminal ileum were used to determine the amount of α-glucoside entering, and apparently disappearing from, the small intestine when either dried-grass or ground maize-based diets were fed. The fate of any α-glucoside entering the small intestine was studied by comparing the net disappearance of such a-glucoside from the small intestine with the absorption of glucose into the mesenteric venous blood.2. Glucose absorption from the small intestine was measured in sheep equipped with catheters in the mesenteric vein and carotid artery. A continuous infusion of [6-3H]glucose was used to determine glucose utilization by the mesenteric-drained viscera and the whole-body glucose turnover rate (GTR).3. The amounts of α-glucoside entering the small intestine when the dried-grass and maize-based diets were given were 13.9 (SE 1.5) and 95.4 (SE 16.2) g/24 h respectively; apparent digestibilities of such α-glucoside in the small intestine were 60 and 90% respectively.4. The net absorption of glucose into the mesenteric venous blood was —2.03 (SE 1.20) and 19.28 (SE 0.75) mmol/h for the dried-grass and maize-based diets respectively. Similarly, total glucose absorption amounted to 1.52 (SE 1.35) and 23.33 (SE 1.86) mmol/h (equivalent to 7 and 101 g/24 h respectively). These values represented 83 and 11 1% of the a-glucoside apparently disappearing from the small intestine, determined using the re-entrant cannulated sheep.5. Total glucose absorption represented 8 and 61% of the whole-body GTR for the dried-grass and maize-based diets respectively. Endogenous glucose production was significantly lower when the sheep were fed on the maize-based diet compared with the dried-grass diet.6. The mesenteric-drained viscera metabolized a small amount of glucose, equivalent to 234 and 17% of the total glucose absorbed for the dried-grass and maize-based diets respectively.7. It is concluded that a large proportion of the starch entering the small intestine of sheep given a maize-based diet is digested and absorbed as glucose, and thus contributes to the whole-body GTR.


1990 ◽  
Vol 259 (2) ◽  
pp. E210-E215 ◽  
Author(s):  
J. R. Lupien ◽  
M. F. Hirshman ◽  
E. S. Horton

The effect of a continuous infusion of norepinephrine (NE) on glucose disposal in vivo was examined in conscious restrained rats using the euglycemic-hyperinsulinemic clamp technique. NE, 1,000 micrograms.kg-1.day-1 (130 nmol.kg-1.h-1) or vehicle (CO) was infused for 10 days in adult male Sprague-Dawley rats using subcutaneously implanted osmotic minipumps. Body weight and food intake were similar in both groups of animals throughout the study. Fasting basal plasma glucose and insulin concentrations were similar in both groups. However, basal hepatic glucose production (HGP) was increased by NE treatment (9.03 +/- 0.63 vs. 13.20 +/- 1.15 mg.kg-1.min-1, P less than 0.05, CO vs. NE, respectively). Insulin infusions of 2, 6, and 200 mU.kg-1.min-1 suppressed HGP to the same degree in both groups. During 2, 6, and 200 mU.kg-1.h-1 insulin infusions the glucose disposal rate was 65, 60, and 13% greater in NE-treated animals than in controls. Acute beta-adrenergic blockade with propranolol infused at 405 nmol.kg-1.h-1 during the glucose clamps did not normalize glucose disposal. These results demonstrate that chronic NE infusion is associated with increased basal glucose turnover and increased insulin sensitivity of peripheral tissues.


1992 ◽  
Vol 12 (4) ◽  
pp. 273-280 ◽  
Author(s):  
M. Kergoat ◽  
Ch. Gespach ◽  
G. Rosselin ◽  
B. Portha

Milk diet has long been recommended in the management of gastrointestinal pathologies. Since milk feeding represents a high fat-low carbohydrate diet and it is acknowledged that insulin resistance is one of the consequences of high fat feeding, it is important to know whether or not chronic milk feeding leads to an impairment of the insulin-mediated glucose metabolism. To examine this question, adult female rats were given raw cow's milk (50% of total calories as lipids) for 18 days. They were compared to rats raised in parallel and fed the standard laboratory diet (15% of total calories as lipids). At the end of the 18 day period, body weight, daily caloric intake, basal plasma glucose and insulin levels in the milk-fed rats were similar to those in the control rats. In vivo insulin action was assessed with the euglycemichyperinsulinemic clamp technique in anesthetized animals. These studies were coupled with the 2-deoxyglucose technique allowing a measurement of glucose utilization by individual tissues. In the milk fed rats: 1) the basal rate of endogenous glucose production was significantly (p<0.01) reduced (by 20%); 2) their hepatic glucose production was however normally suppressed by hyperinsulinemia; 3) their basal glucose utilization rate was significantly (p<0.01) reduced (by 20%); 4) their glucose utilization rate by the whole-body mass or by individual tissues was normally increased by hyperinsulinemia. These results indicate that insulin action in adult rats is not grossly altered after chronic milk-feeding, at least under the present experimental conditions.


1985 ◽  
Vol 54 (2) ◽  
pp. 459-471 ◽  
Author(s):  
A. N. Janes ◽  
T. E. C. Weekes ◽  
D. G. Armstrong

1. The effect of an exogenous supply of glucose, provided by the digestion of maize starch in the small intestine, on endogenous glucose metabolism and insulin action was studied in sheep using the euglycaemic insulin clamp procedure.2. Insulin was infused intravenously at rates of 0.2, 0.5, 1.0 and 6.0 mU/min per kg live weight for four consecutive periods in each of four sheep fed on dried-grass and maize-based diets. Glucose was also infused intravenously at a variable rate, sufficient to maintain the plasma glucose concentration at basal levels. Whole-body rates of glucose metabolism were determined using a continuous infusion of [6-3H]glucose.3. From the resultinginsulin dose-response curves, it was observed that, when the sheep were fed on the dried-grass diet, the responsiveness of glucose metabolism to insulin was less than that reported for non-ruminants.4. When fed the maize-based diet, the glucose metabolic clearance rates (MCR) observed during insulin infusions were significantly greater (P < 0.05) than those observed for the dried-grass diet. However, after correcting for the non-insulin-mediated glucose disposal, differences between diets were not significant.5. The sensitivity of glucose utilization to insulin was not affected by diet. The plasma insulin concentrations causing half-maximal insulin-mediated glucose MCR were 103 (SE 21) and 85 (SE 11) mU/l for the dried-grass and maize-based diets respectively.6. The sensitivity of endogenous glucose production to insulin was also unaffected by diet. The plasma insulin concentrations resulting in the suppression of endogenous glucose production to half the basal level were 80 (SE 26) and 89 (SE 29) mU/l for the dried-grass and maize-based diets respectively.7. It is concluded that the observed increase in glucose utilization on the maize-based diet was due partly to a slight change in responsiveness to insulin and also partly to a change in the rate of non-insulin-mediated glucose disposal.


1990 ◽  
Vol 270 (2) ◽  
pp. 505-510 ◽  
Author(s):  
C Smadja ◽  
J Morin ◽  
P Ferré ◽  
J Girard

A gastric [U-14C]glucose load (4.8 mg/g body wt.) was delivered to unrestrained post-absorptive or 30 h-starved rats bearing peripheral and portal vein catheters and continuously perfused with [3-3H]glucose, in order to compare their metabolic and hormonal responses. In the basal state, portal and peripheral glycaemia were less in starved rats than in rats in the post-absorptive period (P less than 0.01), whereas blood lactate was similar. Portal insulinaemia (P less than 0.05) and protal glucagonaemia (P less than 0.005) were lower in starved rats, but insulin/glucagon ratio was higher in post-absorptive rats (P less than 0.005). The glucose turnover rate was decreased by starvation (P less than 0.005). After glucose ingestion, blood glucose was similar in post-absorptive and starved rats. A large portoperipheral gradient of lactate appeared in starved rats. Portal insulinaemia reached a peak at 9 min, and was respectively 454 +/- 68 and 740 +/- 65 mu-units/ml in starved and post-absorptive rats. Portal glucagonaemia remained stable, but was higher in post-absorptive rats (P less than 0.05). At 60 min after the gastric glucose load, 30% of the glucose was delivered at the periphery in both groups. The total glucose appearance rate was higher in starved rats (P less than 0.05), as was the glucose utilization rate (P less than 0.05), whereas the rate of appearance of exogenous glucose was similar. This was due to a non-suppressed hepatic glucose production in the starved rats, whereas it was totally suppressed in post-absorptive rats. At 1 h after the glucose load, the increase in both liver and muscle glycogen concentration was greater in starved rats. Thus short-term fasting induces an increased portal lactate concentration after a glucose load, and produces a state of liver insulin unresponsiveness for glucose production, whereas the sensitivity of peripheral tissues for glucose utilization is unchanged or even increased. This might allow preferential replenishment of the peripheral stores of glycogen.


1993 ◽  
Vol 265 (2) ◽  
pp. R356-R364 ◽  
Author(s):  
C. H. Lang ◽  
N. Skrepnik ◽  
C. Dobrescu ◽  
A. H. Burns

The present study was performed to determine the time-course for the development of peripheral and hepatic insulin resistance in rats as a result of an increasing tumor burden. Animals were inoculated with Yoshida ascites hepatoma, and studies were conducted during the early phase of tumor growth (day 4) at which time there was no change in food intake and at a later time point (day 8) when the tumor burden was increased and rats demonstrated anorexia. In vivo insulin action was accessed under euglycemic hyperinsulinemic conditions, in which insulin was infused at rates sufficient to produce arterial insulin levels that represent high physiological (3.5 ng/ml) or maximally stimulating values (180 ng/ml). On day 4, tumor-bearing (TB) rats were euglycemic, and whole body glucose turnover was elevated 32%. Insulin-mediated glucose uptake (IMGU) in TB rats was similar to control values at the low insulin infusion rate but reduced by 53% under maximally stimulating conditions. The insulin-induced suppression of glucose production was similar in TB and control animals at this time point. In contrast, on day 8, TB rats were hypoglycemic and glucose turnover was reduced 35%. The impairment in IMGU was more severe than seen earlier, with glucose uptake being reduced 39 and 61% at both levels of hyperinsulinemia. At this time point, the ability of insulin to inhibit glucose production was also impaired. These results indicate that the insulin resistance induced by the Yoshida hepatoma was manifested initially by a reduction in IMGU by peripheral tissues. As the tumor burden increased peripheral insulin resistance became more severe and an impairment in hepatic insulin action was observed.


2012 ◽  
Vol 302 (3) ◽  
pp. E334-E343 ◽  
Author(s):  
Melissa A. Burmeister ◽  
Tura Ferre ◽  
Jennifer E. Ayala ◽  
Emily M. King ◽  
Rochelle M. Holt ◽  
...  

Glucagon-like peptide-1 (GLP-1) receptor knockout (Glp1r−/−) mice exhibit impaired hepatic insulin action. High fat (HF)-fed Glp1r−/− mice exhibit improved, rather than the expected impaired, hepatic insulin action. This is due to decreased lipogenic gene expression and triglyceride accumulation. The present studies overcome these secondary adaptations by acutely modulating GLP-1R action in HF-fed wild-type mice. The central GLP-1R was targeted given its role as a regulator of hepatic insulin action. We hypothesized that acute inhibition of the central GLP-1R impairs hepatic insulin action beyond the effects of HF feeding. We further hypothesized that activation of the central GLP-1R improves hepatic insulin action in HF-fed mice. Insulin action was assessed in conscious, unrestrained mice using the hyperinsulinemic euglycemic clamp. Mice received intracerebroventricular (icv) infusions of artificial cerebrospinal fluid, GLP-1, or the GLP-1R antagonist exendin-9 (Ex-9) during the clamp. Intracerebroventricular Ex-9 impaired the suppression of hepatic glucose production by insulin, whereas icv GLP-1 improved it. Neither treatment affected tissue glucose uptake. Intracerebroventricular GLP-1 enhanced activation of hepatic Akt and suppressed hypothalamic AMP-activated protein kinase. Central GLP-1R activation resulted in lower hepatic triglyceride levels but did not affect muscle, white adipose tissue, or plasma triglyceride levels during hyperinsulinemia. In response to oral but not intravenous glucose challenges, activation of the central GLP-1R improved glucose tolerance. This was associated with higher insulin levels. Inhibition of the central GLP-1R had no effect on oral or intravenous glucose tolerance. These results show that inhibition of the central GLP-1R deteriorates hepatic insulin action in HF-fed mice but does not affect whole body glucose homeostasis. Contrasting this, activation of the central GLP-1R improves glucose homeostasis in HF-fed mice by increasing insulin levels and enhancing hepatic insulin action.


2015 ◽  
Vol 228 (3) ◽  
pp. 127-134 ◽  
Author(s):  
Amanda E Brandon ◽  
Ella Stuart ◽  
Simon J Leslie ◽  
Kyle L Hoehn ◽  
David E James ◽  
...  

An important regulator of fatty acid oxidation (FAO) is the allosteric inhibition of CPT-1 by malonyl-CoA produced by the enzyme acetyl-CoA carboxylase 2 (ACC2). Initial studies suggested that deletion of Acc2 (Acacb) increased fat oxidation and reduced adipose tissue mass but in an independently generated strain of Acc2 knockout mice we observed increased whole-body and skeletal muscle FAO and a compensatory increase in muscle glycogen stores without changes in glucose tolerance, energy expenditure or fat mass in young mice (12–16 weeks). The aim of the present study was to determine whether there was any effect of age or housing at thermoneutrality (29 °C; which reduces total energy expenditure) on the phenotype of Acc2 knockout mice. At 42–54 weeks of age, male WT and Acc2−/− mice had similar body weight, fat mass, muscle triglyceride content and glucose tolerance. Consistent with younger Acc2−/− mice, aged Acc2−/− mice showed increased whole-body FAO (24 h average respiratory exchange ratio=0.95±0.02 and 0.92±0.02 for WT and Acc2−/− mice respectively, P<0.05) and skeletal muscle glycogen content (+60%, P<0.05) without any detectable change in whole-body energy expenditure. Hyperinsulinaemic–euglycaemic clamp studies revealed no difference in insulin action between groups with similar glucose infusion rates and tissue glucose uptake. Housing Acc2−/− mice at 29 °C did not alter body composition, glucose tolerance or the effects of fat feeding compared with WT mice. These results confirm that manipulation of Acc2 may alter FAO in mice, but this has little impact on body composition or insulin action.


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