Effects Of Glucocorticoids On The Glucose Transport Of Skeletal Muscle In Broiler Chickens

The experiments were conducted to investigate the characteristics of glucose transport on the skeletal muscles of broilers (Gallus gallus domesticus). In vivo, exogenous glucocorticoid was used to treat the chicken. Changes of subtype and mRNA expression level of glucose transporters were measured and analyzed. In vitro, chicken myoblast was used to study. Changes of mRNA expression level of glucose transporters and glucose uptake were measured and analyzed. We hope our study can provide the evidence of theory for the insulin resistance and turbulence of glucose metabolism on skeletal muscles of broilers.In experiment 1, 72 male broilers (Arbor Acres) with similar body weight of 7 day were divided into 3 groups at random: DEX, NC and PF. The results indicate that, after seven days DEX exposure, birds of DEX show lower body weight and higher feed/weight ratio. The breast yield (%) and thigh yield (%) had no significant difference. The concentration of plasma uric acid (UA), insulin (INS) and glucose (GLU) were increased. The mRNA of five glucose transporters (GLUT) was determined in chicken muscles, and we did not find the GLUT4-like protein.In experiment 2, the chicken myoblast was cultured in basal medium, with 10% FBS, 37℃, 5% CO2. After 72 h, Cell was cultured 4h without FBS. Trial 1, Cells were divided into 4 groups: Control, LY294002+DEX, Rapamycin+DEX and DEX group. After 3h, the 2-DG uptake speed was determined. Trial 2, Cells were divided into 4 groups at random: Control, INS, INS+DEX and RU486+INS+DEX group. After 3h, the 2-DG uptake speed was determined. The results in trial 1 indicate that the 2-DG uptake speed was declined significantly by DEX and this decline is relieved by LY294002 or Rapamycin; in trial 2, insulin increases the 2-DG uptake speed and this effect is esesd by DEX, but not significantly.In experiment 3, the chicken myoblast was cultured in high glucose DMEM medium as basal medium, with 10% FBS, 37℃, 5% CO2 . After 72 h, Cell was cultured 4h without FBS. Trial 1, Cells were divided into 5 groups at random and cultured with the basis medium which has 0, 0.2, 1, 5 or 25 U/ml insulin. After 12h, the RNA was obtained. Trial 2, Cells were divided into 4 groups at random: Control, DEX, INS and INS+DEX. After 12h, the RNA was obtained.The results indicate that: In trial 1, following the insulin increasing, the mRNA level of GLUT1 and insulin receptor (IR) was respectively increased and then decreased. In trial 2, the significantly increased GLUT1 mRNA level indicated the insulin sensitive,indicating that GLUT1 may play an important role in the insulin stimulated glucose transport in chicken muscle.In experiment 4, the chicken myoblast was cultured in basal medium, with 10% FBS, 37℃, 5% CO2. After 72 h, Cell was cultured 4h without FBS. Trial 1, Cells were divided into 2 groups at random: the high glucose group (with 4.5 g/liter glucose), the control group (with 1g/liter glucose). After 12h, the RNA was obtained. Trial 2, Cells were divided into 2 groups at random: the control group (with 1 g/liter glucose), the no glucose group (with 0 g/liter glucose). After 12h, the RNA was obtained. The results in trial 1 indicate that the mRNA level of GLUT1 and GLUT3 were increased significantly by the hidh glucose; results of Trial 2 showed that there is no significantly effect on GLUT1, GLUT3, GLUT8 and the mRNA levels of GLUT11, GLUT12 were too low to be detected.In conclusion, in broiler chickens skeletal muscle the characteristics of GLUT1 which is sensitive to insulin stimulation and reduced by glucocorticoids, may play an important role in glucose metabolic disorder which is induced by glucocorticoids.