title: GH signaling in human adipose and muscle tissue during 'feast and famine': amplification of exercise stimulation following fasting compared to glucose administration.
abstract: OBJECTIVE
  Fasting and exercise stimulates, whereas glucose suppresses GH secretion, but it is uncertain how these conditions impact GH signaling in peripheral tissues. To test the original 'feast and famine hypothesis' by Rabinowitz and Zierler, according to which the metabolic effects of GH are predominant during fasting, we specifically hypothesized that fasting and exercise act in synergy to increase STAT-5b target gene expression.
  
  
  METHODS
  Eight healthy men were studied on two occasions in relation to a 1 h exercise bout: i) with a concomitant i.v. glucose infusion ('feast') and ii) after a 36 h fast ('famine'). Muscle and fat biopsy specimens were obtained before, immediately after, and 30 min after exercise.
  
  
  RESULTS
  GH increased during exercise on both examination days and this effect was amplified by fasting, and free fatty acid (FFA) levels increased after fasting. STAT-5b phosphorylation increased similarly following exercise on both occasions. In adipose tissue, suppressors of cytokine signaling 1 (SOCS1) and SOCS2 were increased after exercise on the fasting day and both fasting and exercise increased cytokine inducible SH2-containing protein (CISH). In muscle, SOCS2 and CISH mRNA were persistently increased after fasting. Muscle SOCS1, SOCS3, and CISH mRNA expression increased, whereas SOCS2 decreased after exercise on both examination days.
  
  
  CONCLUSIONS
  This study demonstrates that fasting and exercise act in tandem to amplify STAT-5b target gene expression (SOCS and CISH) in adipose and muscle tissue in accordance with the 'feast and famine hypothesis'; the adipose tissue signaling responses, which hitherto have not been scrutinized, may play a particular role in promoting FFA mobilization.
authors.affiliation: Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark Mikkel.Vendelbo@ki.au.dk.
authors.forename: Mikkel H
authors.initials: MH
authors.lastname: Vendelbo
authors.affiliation: Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark.
authors.forename: Britt
authors.initials: B
authors.lastname: Christensen
authors.affiliation: Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark.
authors.forename: Solbritt B
authors.initials: SB
authors.lastname: Grønbæk
authors.affiliation: Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Høgild
authors.affiliation: Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Madsen
authors.affiliation: Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark.
authors.forename: Steen B
authors.initials: SB
authors.lastname: Pedersen
authors.affiliation: Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark.
authors.forename: Jens O L
authors.initials: JO
authors.lastname: Jørgensen
authors.affiliation: Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Jessen
authors.affiliation: Departments of Endocrinology and Internal MedicineNuclear Medicine and PET CenterResearch Laboratory for Biochemical PathologyAarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Møller
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000328:Adult; D015444:Exercise / Q000502:physiology*; D005215:Fasting / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology*; D019382:Human Growth Hormone / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*; D050799:STAT5 Transcription Factor / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D000071222:Suppressor of Cytokine Signaling 1 Protein; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D013549:Sweetening Agents / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D005230:Fatty Acids, Nonesterified; D005947:Glucose; D019382:Human Growth Hormone; D012333:RNA, Messenger; D050799:STAT5 Transcription Factor; D000071222:Suppressor of Cytokine Signaling 1 Protein; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D013549:Sweetening Agents; C108944:SOCS1 protein, human; C106643:SOCS2 protein, human; C106644:SOCS3 protein, human; C494095:STAT5B protein, human