title: Post-receptor crosstalk between growth hormone and insulin signal in rats born small for gestational age with catch-up growth.
abstract: OBJECTIVE
  Insulin resistance has been observed in individuals born small for gestational age (SGA) with catch-up growth (CUG), yet the mechanisms involved remain unclear. This study examined the role of GH and insulin signaling crosstalk in insulin resistance of SGA rats with CUG.
  
  
  METHODS
  SGA rats were developed by dietary restriction in pregnant rats. GH receptor inhibition was performed on four-week old CUG-SGA and AGA rats. Phosphorylation of IRS-1, AKT, and ERK, and expression of SOCS3 in the skeletal muscle were determined via immunoblot analysis at baseline and after insulin stimulation in CUG-SGA, NCUG-SGA and AGA groups.
  
  
  RESULTS
  Compared to AGA controls, phosphorylation of IRS-1 and AKT in response to insulin stimulation in CUG-SGA rats was significantly blunted (P<0.05), and phosphorylation of ERK at baseline was dramatically activated (P<0.05). SOCS3 expression was significantly increased in CUG-SGA compared to AGA (P = 0.001) and NCUG-SGA (P = 0.006) rats, and was significantly suppressed following GHR inhibition (P<0.05). Furthermore, phosphorylation of IRS-1 and AKT in response to insulin stimulation increased after GHR inhibition (P<0.05).
  
  
  CONCLUSIONS
  Insulin resistance in CUG-SGA rats is associated with impairment of IRS-1-PI3K-AKT signaling, which may result from GH signaling-induced up-regulation of SOCS3.
authors: Department of Pediatrics, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China; Department of Pediatrics, the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
authors: Hong-Zhu
authors: HZ
authors: Deng
authors: Department of Infectious diseases, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
authors: Hong
authors: H
authors: Deng
authors: Department of Pediatrics, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
authors: Chao-Qun
authors: CQ
authors: Cen
authors: Department of Pediatrics, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
authors: Kai-Yun
authors: KY
authors: Chen
authors: Department of Pediatrics, the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.
authors: Min-Lian
authors: ML
authors: Du
mesh_terms: D000818:Animals; D001724:Birth Weight; D005260:Female; D005786:Gene Expression Regulation; D005865:Gestational Age; D007333:Insulin Resistance; D008297:Male; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D020239:Receptor Cross-Talk; D011972:Receptor, Insulin / Q000378:metabolism*; D011986:Receptors, Somatotropin / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D011986:Receptors, Somatotropin; D011972:Receptor, Insulin