title: IL-6 gene expression in human adipose tissue in response to exercise--effect of carbohydrate ingestion.
abstract: Interleukin-6 (IL-6) is a cytokine involved in a number of immunological processes, but it is also linked to exercise and possibly energy status. During exercise, muscle IL-6 mRNA levels and plasma IL-6 levels are increased and further augmented when intramuscular glycogen levels are low. In contrast, the increase in plasma IL-6 is blunted if carbohydrate is administered, indicating a substrate-regulated induction of IL-6 in human skeletal muscle. Recent studies have demonstrated that IL-6 is also released from adipose tissue in response to an exercise bout. Furthermore, IL-6 has been demonstrated to have a lipolytic effect, thus possibly playing a role in mobilisation of energy as free fatty acids (FFA) in response to exercise. The purpose of the present study was to investigate the gene expression pattern of IL-6 in adipose tissue in response to exercise, and to determine whether gene expression was affected by the ingestion of carbohydrate. Eight male subjects performed 3 h of bicycling with ingestion of a carbohydrate drink or placebo. Fat biopsy samples and blood samples were obtained before, during and in the recovery phase of exercise. Both plasma IL-6 and adipose IL-6 mRNA levels increased in response to exercise. IL-6 gene expression was lower (P<0.05) in the CHO trial (1.98-fold increase, confidence interval (CI) 1.16-3.83) compared with the control (6.49-fold increase, CI 3.57-13.91) at end of exercise. Furthermore, CHO ingestion blunted the increase in plasma IL-6 levels (P<0.05) at end of exercise (26.0+/-3.7 pg ml(-1) in the control vs. 15.6+/-2.4 pg ml(-1) in the CHO trial). In conclusion, exercise results in an increase in IL-6 gene expression in adipose tissue in response to exercise, an effect that is significantly blunted by ingestion of carbohydrate.
authors.affiliation: Department of Infectious Diseases, Rigshospitalet, Denmark.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Keller
authors.forename: Pernille
authors.initials: P
authors.lastname: Keller
authors.forename: Sonya
authors.initials: S
authors.lastname: Marshal
authors.forename: Bente Klarlund
authors.initials: BK
authors.lastname: Pedersen
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000328:Adult; D000818:Animals; D001642:Bicycling / Q000502:physiology; D001786:Blood Glucose / Q000378:metabolism; D016466:CHO Cells; D006224:Cricetinae; D017931:DNA Primers; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D015444:Exercise / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics*; D008297:Male; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D001786:Blood Glucose; D017931:DNA Primers; D004040:Dietary Carbohydrates; D005230:Fatty Acids, Nonesterified; D015850:Interleukin-6; D012313:RNA