scholarly journals Effect of diabetes and fasting on GLUT-4 (muscle/fat) glucose-transporter expression in insulin-sensitive tissues. Heterogeneous response in heart, red and white muscle

1992 ◽  
Vol 282 (3) ◽  
pp. 765-772 ◽  
Author(s):  
M Camps ◽  
A Castelló ◽  
P Muñoz ◽  
M Monfar ◽  
X Testar ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
White Adipose Tissue ◽  
White Muscle ◽  
Glucose Transporter ◽  
Mrna Levels ◽  
Glut 4 ◽  
Brown Adipose ◽  
Red Muscle

1. GLUT-4 glucose-transporter protein and mRNA levels were assessed in heart, red muscle and white muscle, as well as in brown and white adipose tissue from 7-day streptozotocin-induced diabetic and 48 h-fasted rats. 2. In agreement with previous data, white adipose tissue showed a substantial decrease in GLUT-4 mRNA and protein levels in response to both diabetes and fasting. Similarly, GLUT-4 mRNA and protein markedly decreased in brown adipose tissue in both insulinopenic conditions. 3. Under control conditions, the level of expression of GLUT-4 protein content differed substantially in heart, red and white skeletal muscle. Thus GLUT-4 protein was maximal in heart, and red muscle had a greater GLUT-4 content compared with white muscle. In spite of the large differences in GLUT-4 protein content, GLUT-4 mRNA levels were equivalent in heart and red skeletal muscle. 4. In heart, GLUT-4 mRNA decreased to a greater extent than GLUT-4 protein in response to diabetes and fasting. In contrast, red muscle showed a greater decrease in GLUT-4 protein than in mRNA in response to diabetes or fasting, and in fact no decrease in GLUT-4 mRNA content was detectable in fasting. On the other hand, preparations of white skeletal muscle showed a substantial increase in GLUT-4 mRNA under both insulinopenic conditions, and that was concomitant to either a modest decrease in GLUT-4 protein in diabetes or to no change in fasting. 5. These results indicate that (a) the effects of diabetes and fasting are almost identical and lead to changes in GLUT-4 expression that are tissue-specific, (b) white adipose tissue, brown adipose tissue and heart respond similarly to insulin deficiency by decreasing GLUT-4 mRNA to a larger extent than GLUT-4 protein, and (c) red and white skeletal muscle respond to insulinopenic conditions in a heterogeneous manner which is characterized by enhanced GLUT-4 mRNA/protein ratios.

scholarly journals Glucose transporter expression and glucose utilization in skeletal muscle and brown adipose tissue during starvation and re-feeding

1992 ◽  
Vol 282 (1) ◽  
pp. 231-235 ◽  
Author(s):  
D M Smith ◽  
S R Bloom ◽  
M C Sugden ◽  
M J Holness
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Tibialis Anterior ◽  
Glucose Transporter ◽  
Glucose Utilization ◽  
Interscapular Brown Adipose Tissue ◽  
Glut 4 ◽  
Mrna Concentration ◽  
Brown Adipose ◽  
Transporter Expression

Starvation (48 h) decreased the concentration of mRNA of the insulin-responsive glucose transporter isoform (GLUT 4) in interscapular brown adipose tissue (IBAT) (56%) and tibialis anterior (10%). Despite dramatic [7-fold (tibialis anterior) and 40-fold (IBAT)] increases in glucose utilization after 2 and 4 h of chow re-feeding, no significant changes in GLUT 4 mRNA concentration were observed in these tissues over this re-feeding period. The results exclude changes in GLUT 4 mRNA concentration in mediating the responses of glucose transport in these tissues to acute re-feeding after prolonged starvation.

scholarly journals Immuno-localization of the insulin regulatable glucose transporter in brown adipose tissue of the rat.

1991 ◽  
Vol 113 (1) ◽  
pp. 123-135 ◽  
Author(s):  
J W Slot ◽  
H J Geuze ◽  
S Gigengack ◽  
G E Lienhard ◽  
D E James
Keyword(s):  
Adipose Tissue ◽  
Cell Surface ◽  
Brown Adipose Tissue ◽  
Glucose Transporter ◽  
Cell Labeling ◽  
Coated Pits ◽  
Fixed Tissue ◽  
Glut 4 ◽  
Brown Adipose ◽  
Early Endosomes

Antibodies specific for the insulin-regulatable glucose transporter (GLUT 4) were used to immunolocalize this protein in brown adipose tissue from basal- and insulin-treated rats. Cryosections of fixed tissue were incubated with antibodies, which were subsequently labeled with Protein A/gold and examined by EM. Antibodies against albumin and cathepsin D were also used with gold particles of different sizes to identify early and late endosomes, respectively. Under basal conditions 99% of the GLUT 4 labeling was located within the cell. Labeling was predominantly in the trans-Golgi reticulum and tubulo-vesicular structures elsewhere in the cytoplasm. In insulin-stimulated cells approximately 40% of the GLUT 4 labeling was at the cell surface, where it was randomly distributed, except for occasional clustering in coated pits. Moreover, after insulin treatment, GLUT 4 was also enriched in early endosomes. We conclude that translocation of GLUT 4 to the cell surface is the major mechanism by which insulin increases glucose transport. In addition, these results suggest that in the presence of insulin GLUT 4 recycles from the cell surface, probably via the coated pit-endosome pathway that has been characterized for cell surface receptors, and also that insulin causes the redistribution of GLUT 4 by stimulating exocytosis from GLUT 4-containing tubulo-vesicular structures, rather than by slowing endocytosis of GLUT 4.

Increased expression of glucose transporter GLUT-4 in brown adipose tissue of fasted rats after cold exposure

1993 ◽  
Vol 264 (6) ◽  
pp. E890-E895 ◽  
Author(s):  
Y. Shimizu ◽  
H. Nikami ◽  
K. Tsukazaki ◽  
U. F. Machado ◽  
H. Yano ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Glucose Uptake ◽  
Cold Exposure ◽  
De Novo ◽  
Mrna Levels ◽  
Glut 4 ◽  
Increase Glucose Uptake ◽  
Brown Adipose ◽  
Stimulation Of

Cold exposure has been shown to increase glucose uptake specifically in brown adipose tissue (BAT), the major site for sympathetically controlled metabolic heat production. In this study, the relationship between glucose uptake and glucose transporters (GLUT) was examined in rats exposed to cold for various periods. To minimize the stimulatory effect of circulating insulin, all animals were starved for 20-24 h before the measurements. Acute (4 h) cold exposure had no effect on protein and mRNA levels of GLUT-4, the predominant isoform of GLUT in BAT, despite a significant increase in cellular glucose uptake. Prolonged (1-10 days) cold exposure produced a parallel increase in GLUT-4 expression and glucose uptake in BAT. In contrast, cold exposure had no noticeable effect on GLUT-1, another isoform of GLUT in BAT, and on GLUT-4 in other insulin-sensitive tissues such as white adipose tissue and muscles. The increased glucose uptake and GLUT-4 expression were completely abolished after surgical sympathetic denervation. These findings suggest that cold exposure increases glucose uptake in BAT by at least two distinct mechanisms, both of which are dependent on sympathetic nerve: 1) an increase in the amount of GLUT-4 due to the stimulation of its de novo synthesis, and 2) an increase without stimulation of GLUT synthesis, probably due to the change in the transport activity of GLUT-4 and/or its translocation from an intracellular pool to the plasma membrane.

scholarly journals Changes in insulin-receptor mRNA levels in skeletal muscle and brown adipose tissue of weanling rats during fasting and refeeding

1992 ◽  
Vol 68 (3) ◽  
pp. 583-592 ◽  
Author(s):  
Rachel M. Knott ◽  
Paul Trayhurn ◽  
John E. Hesketh
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Insulin Receptor ◽  
Uncoupling Protein ◽  
Mrna Level ◽  
Mrna Levels ◽  
Receptor Mrna ◽  
Brown Adipose ◽  
Fasting And Refeeding

Tissue-specific alterations in insulin sensitivity occur in response to fasting and refeeding, as part of the integrated adaptive mechanisms employed to adjust to major changes in nutritional status. In the present study the effects of fasting and refeeding on insulin-receptor, actin and myosin mRNA levels in skeletal muscle, and insulin-receptor and uncoupling-protein mRNA in brown adipose tissue of rats have been examined. Insulin-receptor mRNA levels increased markedly in both skeletal muscle and brown adipose tissue after a 40 h fast, the increase being greater in brown fat (8-fold) than in muscle (2-fold). On refeeding for 4 h, the insulin-receptor mRNA level in both tissues declined rapidly to control levels. An increase in insulin-receptor mRNA level was also observed in brown adipose tissue after a 16 h fast, although not in skeletal muscle. In contrast to the insulin-receptor mRNA, the level of the mRNA for the mitochondrial uncoupling protein declined markedly in brown adipose tissue during a 40 h fast. These results indicate that insulin-receptor mRNA levels are modulated in response to the alterations in nutritional status that occur during fasting and refeeding; this may reflect a nutritional influence on transcription of the receptor-protein gene

Anti-obesity and anti-diabetic effects of CL316,243, a highly specific β3-adrenoceptor agonist, in Otsuka Long-Evans Tokushima Fatty rats: induction of uncoupling protein and activation of glucose transporter 4 in white fat

1997 ◽  
Vol 136 (4) ◽  
pp. 429-437 ◽  
Author(s):  
Tsunekazu Umekawa ◽  
Toshihide Yoshida ◽  
Naoki Sakane ◽  
Masayuki Saito ◽  
Kenzo Kumamoto ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
White Adipose Tissue ◽  
Glucose Transporter ◽  
Uncoupling Protein ◽  
Glucose Transporter 4 ◽  
Adrenoceptor Agonist ◽  
Brown Adipose ◽  
Long Evans ◽  
White Fat

Abstract The anti-obesity and anti-diabetic effects of a highly specific β3-adrenoceptor agonist, CL316.243 (CL; β1:β2:β3=0:1:100 000), were investigated in Otsuka Long-Evans Tokushima Fatty (fatty) and LongEvans Tokushima Otsuka (control) rats. Daily injection of CL (0·1 mg/kg, s.c.) to these rats (10 weeks old) for 14 weeks caused a significant reduction in body weight (fatty, 27% control, 15%), associated with a marked decrease in fat pad weight (inguinal: fatty, 60%; control, 36%; retroperitoneal: fatty, 75%; control, 77%) without affecting food intake. The levels of uncoupling protein mRNA and protein levels of uncoupling protein (UCP), as well as guanosine 5′-diphosphate-binding (a reliable index of thermogenesis) in brown adipose tissue, were lower in the fatty than in the control rats. However, after CL treatment, these parameters in brown adipose tissue increased significantly 2- to 3-fold in both groups. Furthermore, uncoupling protein was induced in white adipose tissue as well as in brown adipose tissue. The fatty rats showed hyperglycemia and hyperinsulinemia during the glucose tolerance test, but CL ameliorated these parameters. These findings suggest that decreased thermogenesis in brown adipose tissue may be one of the causes of obesity in the fatty rats and that administration of CL prevents obesity by decreasing white fat mass, by activating brown adipose tissue thermogenesis, and by inducing uncoupling protein in white adipose tissue. Furthermore, CL treatment may inhibit diabetes mellitus by ameliorating obesity and by activating glucose transporter 4 in white adipose tissue and brown adipose tissue. European Journal of Endocrinology 136 429–437

Development and regulation of glucose transporter and hexokinase expression in rat

1994 ◽  
Vol 266 (4) ◽  
pp. E548-E559 ◽  
Author(s):  
C. Postic ◽  
A. Leturque ◽  
R. L. Printz ◽  
P. Maulard ◽  
M. Loizeau ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Insulin Sensitivity ◽  
Brown Adipose Tissue ◽  
Glucose Transporter ◽  
Fetal Liver ◽  
Rat Tissues ◽  
Fetal Life ◽  
Glut 1 ◽  
Glut 4 ◽  
Brown Adipose

The ontogenesis of the glucose transporters GLUT-1, GLUT-2, and GLUT-4 and the hexokinases HK-I, HK-II, and HK-IV (glucokinase) was studied in rat tissues. In brown adipose tissue, high levels of GLUT-4 and HK-II were observed during fetal life; both decreased at birth and then increased throughout development. At birth, cold exposure increased GLUT-4 and HK-II expression in brown adipose tissue, whereas fasting decreased it. GLUT-1 and HK-I were present in fetal muscle, but GLUT-4 and HK-II were absent. The coordinate appearance of GLUT-4 and HK-II in skeletal muscle was concomitant with the acquisition of insulin sensitivity after weaning. In the heart, the glucose transporter isoform switched from GLUT-1 to GLUT-4 during the suckling period. The coordinate expression of GLUT-4 and HK-II in heart was observed after weaning. GLUT-2, detected in fetal liver, increased throughout development. GLUT-1 and HK-I were detectable in fetal liver, whereas glucokinase appeared after weaning. Consumption of a high-carbohydrate diet after weaning increased GLUT-4 and HK-II in muscle and GLUT-2 in liver, whereas consumption of a high-fat diet prevented these changes. These results showed that 1) GLUT-1 and HK-I are abundant in most fetal rat tissues, 2) GLUT-4 and HK-II expression is associated with the appearance of tissue insulin sensitivity, and 3) GLUT-2 is expressed early in liver, before the appearance of glucokinase.

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