title: Down-regulation of insulin-like growth factor I (IGF-I) in the mouse diaphragm during sepsis.
abstract: BACKGROUND
  Diaphragmatic muscle impairment is an important cause of respiratory failure during sepsis. Insulin-like growth factor I (IGF-I) is an anabolic growth factor which prevents muscle degradation and wasting during sepsis, but its role in the diaphragmatic muscle during sepsis is unknown. The aim of this study was to investigate the expression of IGF-I in the diaphragmatic muscle in a murine model of sepsis induced by lipopolysaccharide (LPS).
  
  
  METHODS
  Male B57 mice were peritoneally injected with LPS, and were killed and studied at different time-points, 24 h, 48 h, 72 h, and 96 h after injection. Diaphragm sarcolemmal damage was visualized by orange tracer dye infusion, and the expression of IGF-I, interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in diaphragm tissue extracts were measured using ELISA.
  
  
  RESULTS
  LPS induced sarcolemmal damage in diaphragm myofibers from 24 h to 96 h, which was accompanied by a significant increase in IL-1β expression in the tissues while IGF-I levels were down-regulated. No change in TNF-α was observed. Body weights of animals were also reduced, especially at 96 h.
  
  
  CONCLUSIONS
  The expression of IGF-I in diaphragm tissues was down-regulated during sepsis- induced diaphragm myofiber damage, suggesting that IGF-I may be an important factor in the regulation of diaphragm myofiber repair. Further studies are needed to examine the mechanisms involved.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan. mengchih@adm.cgmh.org.tw
authors.forename: Meng-Chih
authors.initials: MC
authors.lastname: Lin
authors.forename: Sum Yee
authors.initials: SY
authors.lastname: Leung
authors.forename: Wen-Feng
authors.initials: WF
authors.lastname: Fang
authors.forename: Chien-Hung
authors.initials: CH
authors.lastname: Chin
authors.forename: Kian Fan
authors.initials: KF
authors.lastname: Chung
mesh_terms: D000818:Animals; D001835:Body Weight; D003964:Diaphragm / Q000737:chemistry* / Q000473:pathology; D015536:Down-Regulation; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000502:physiology; D053583:Interleukin-1beta / Q000032:analysis; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018805:Sepsis / Q000378:metabolism* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
chemical_list: D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D007334:Insulin-Like Growth Factor I