TY - JOUR
T1 - Pioglitazone stimulates AMP-activated protein kinase signalling and increases the expression of genes involved in adiponectin signalling, mitochondrial function and fat oxidation in human skeletal muscle in vivo
T2 - A randomised trial
AU - Coletta, D. K.
AU - Sriwijitkamol, A.
AU - Wajcberg, E.
AU - Tantiwong, P.
AU - Li, M.
AU - Prentki, M.
AU - Madiraju, M.
AU - Jenkinson, C. P.
AU - Cersosimo, E.
AU - Musi, N.
AU - DeFronzo, R. A.
N1 - Funding Information:
Trial registration: NCT 00816218 Funding: This trial was funded by National Institutes of Health Grant DK24092, VA Merit Award, GCRC Grant RR01346, Executive Research Committee Research Award from the University of Texas Health Science Center at San Antonio, American Diabetes Association Junior Faculty Award, American Heart Association National Scientist Development Grant, Takeda Pharmaceuticals North America Grant and Canadian Institute of Health Research Grant.
Funding Information:
Acknowledgements This work was supported by NIH grant DK24092 (R. A. DeFronzo), a VA Merit Award (R. A. DeFronzo), GCRC grant RR01346, an Executive Research Committee Research Award from the University of Texas Health Science Center at San Antonio (N. Musi), an American Diabetes Association Junior Faculty Award (N. Musi), an American Heart Association National Scientist Development Grant (D. K. Coletta), a grant from Takeda Pharmaceuticals North America and a grant from the Canadian Institute of Health Research (M. Prentki). We thank all the patients who participated in the studies and the Texas Diabetes Institute nurses who helped to perform the studies. We thank N. Cyr for excellent technical assistance.
PY - 2009/4
Y1 - 2009/4
N2 - Aims/hypothesis: The molecular mechanisms by which thiazolidinediones improve insulin sensitivity in type 2 diabetes are not fully understood. We hypothesised that pioglitazone would activate the adenosine 5́- monophosphate-activated protein kinase (AMPK) pathway and increase the expression of genes involved in adiponectin signalling, NEFA oxidation and mitochondrial function in human skeletal muscle. Methods: A randomised, double-blind, parallel study was performed in 26 drug-naive type 2 diabetes patients treated with: (1) pioglitazone (n∈=∈14) or (2) aggressive nutritional therapy (n∈=∈12) to reduce HbA1c to levels observed in the pioglitazone-treated group. Participants were assigned randomly to treatment using a table of random numbers. Before and after 6 months, patients reported to the Clinical Research Center of the Texas Diabetes Institute for a vastus lateralis muscle biopsy followed by a 180 min euglycaemic-hyperinsulinaemic (80 mU m-2 min-1) clamp. Results: All patients in the pioglitazone (n∈=∈14) or nutritional therapy (n∈=∈12) group were included in the analysis. Pioglitazone significantly increased plasma adiponectin concentration by 79% and reduced fasting plasma NEFA by 35% (both p∈<∈0.01). Following pioglitazone, insulin-stimulated glucose disposal increased by 30% (p∈<∈0.01), and muscle AMPK and acetyl-CoA carboxylase (ACC) phosphorylation increased by 38% and 53%, respectively (p∈<∈0.05). Pioglitazone increased mRNA levels for adiponectin receptor 1 and 2 genes (ADIPOR1, ADIPOR2), peroxisome proliferator-activated receptor gamma, coactivator 1 gene (PPARGC1) and multiple genes involved in mitochondrial function and fat oxidation. Despite a similar reduction in HbA1c and similar improvement in insulin sensitivity with nutritional therapy, there were no significant changes in muscle AMPK and ACC phosphorylation, or the expression of ADIPOR1, ADIPOR2, PPARGC1 and genes involved in mitochondrial function and fat oxidation. No adverse (or unexpected) effects or side effects were reported from the study. Conclusions/ interpretations: Pioglitazone increases plasma adiponectin levels, stimulates muscle AMPK signalling and increases the expression of genes involved in adiponectin signalling, mitochondrial function and fat oxidation. These changes may represent an important cellular mechanism by which thiazolidinediones improve skeletal muscle insulin sensitivity. Trial registration: NCT 00816218 Funding: This trial was funded by National Institutes of Health Grant DK24092, VA Merit Award, GCRC Grant RR01346, Executive Research Committee Research Award from the University of Texas Health Science Center at San Antonio, American Diabetes Association Junior Faculty Award, American Heart Association National Scientist Development Grant, Takeda Pharmaceuticals North America Grant and Canadian Institute of Health Research Grant.
AB - Aims/hypothesis: The molecular mechanisms by which thiazolidinediones improve insulin sensitivity in type 2 diabetes are not fully understood. We hypothesised that pioglitazone would activate the adenosine 5́- monophosphate-activated protein kinase (AMPK) pathway and increase the expression of genes involved in adiponectin signalling, NEFA oxidation and mitochondrial function in human skeletal muscle. Methods: A randomised, double-blind, parallel study was performed in 26 drug-naive type 2 diabetes patients treated with: (1) pioglitazone (n∈=∈14) or (2) aggressive nutritional therapy (n∈=∈12) to reduce HbA1c to levels observed in the pioglitazone-treated group. Participants were assigned randomly to treatment using a table of random numbers. Before and after 6 months, patients reported to the Clinical Research Center of the Texas Diabetes Institute for a vastus lateralis muscle biopsy followed by a 180 min euglycaemic-hyperinsulinaemic (80 mU m-2 min-1) clamp. Results: All patients in the pioglitazone (n∈=∈14) or nutritional therapy (n∈=∈12) group were included in the analysis. Pioglitazone significantly increased plasma adiponectin concentration by 79% and reduced fasting plasma NEFA by 35% (both p∈<∈0.01). Following pioglitazone, insulin-stimulated glucose disposal increased by 30% (p∈<∈0.01), and muscle AMPK and acetyl-CoA carboxylase (ACC) phosphorylation increased by 38% and 53%, respectively (p∈<∈0.05). Pioglitazone increased mRNA levels for adiponectin receptor 1 and 2 genes (ADIPOR1, ADIPOR2), peroxisome proliferator-activated receptor gamma, coactivator 1 gene (PPARGC1) and multiple genes involved in mitochondrial function and fat oxidation. Despite a similar reduction in HbA1c and similar improvement in insulin sensitivity with nutritional therapy, there were no significant changes in muscle AMPK and ACC phosphorylation, or the expression of ADIPOR1, ADIPOR2, PPARGC1 and genes involved in mitochondrial function and fat oxidation. No adverse (or unexpected) effects or side effects were reported from the study. Conclusions/ interpretations: Pioglitazone increases plasma adiponectin levels, stimulates muscle AMPK signalling and increases the expression of genes involved in adiponectin signalling, mitochondrial function and fat oxidation. These changes may represent an important cellular mechanism by which thiazolidinediones improve skeletal muscle insulin sensitivity. Trial registration: NCT 00816218 Funding: This trial was funded by National Institutes of Health Grant DK24092, VA Merit Award, GCRC Grant RR01346, Executive Research Committee Research Award from the University of Texas Health Science Center at San Antonio, American Diabetes Association Junior Faculty Award, American Heart Association National Scientist Development Grant, Takeda Pharmaceuticals North America Grant and Canadian Institute of Health Research Grant.
KW - AMP kinase
KW - Adiponectin
KW - Insulin sensitivity
KW - Mitochondrial
KW - Muscle
KW - Pioglitazone
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U2 - 10.1007/s00125-008-1256-9
DO - 10.1007/s00125-008-1256-9
M3 - Article
C2 - 19169664
AN - SCOPUS:61449222837
SN - 0012-186X
VL - 52
SP - 723
EP - 732
JO - Diabetologia
JF - Diabetologia
IS - 4
ER -