title: Effects of adrenal hormones on the expression of adiponectin and adiponectin receptors in adipose tissue, muscle and liver.
abstract: BACKGROUND
  Adiponectin, an insulin-sensitive hormone that is primarily synthesized in adipose tissue, exerts its effects by binding to two receptors, adipoR1 and adipoR2. Little is known regarding the effects of glucocorticoids on the expression of adiponectin receptors.
  
  
  METHODS
  Male Wistar rats were bilaterally adrenalectomized and treated with dexamethasone (0.2 mg/100 g) twice daily for 3 days. To analyze the potential effects of glucocorticoids, rats received two daily injections of the glucocorticoid receptor antagonist (RU-486, 5.0 mg) over the course of 3 days. Additionally, 3T3-L1 adipocytes and C2C12 myotubes were treated with dexamethasone, adrenaline or RU-486. The gene expression of adiponectin, adipoR1 and adipoR2 was determined by real-time PCR, and protein secretion was examined by Western blotting using lysates from retroperitoneal, epididymal and subcutaneous adipose tissue depots, liver and muscle.
  
  
  RESULTS
  In rats, excess glucocorticoids increased the levels of insulin in serum and decreased serum adiponectin concentrations, whereas adrenalectomy decreased the mRNA expression of adiponectin (3-fold) and adipoR2 (7-fold) in epididymal adipose tissue and increased adipoR2 gene expression in muscle (3-fold) compared to control group sham-operated. Dexamethasone treatment did not reverse the effects of adrenalectomy, and glucocorticoid receptor blockade did not reproduce the effects of adrenalectomy. In 3T3-L1 adipocytes, dexamethasone and adrenaline both increased adipoR2 mRNA levels, but RU-486 reduced adipoR2 gene expression in vitro.
  
  
  CONCLUSIONS
  Dexamethasone treatment induces a state of insulin resistance but does not affect adiponectin receptor expression in adipose tissue. However, the effects of catecholamines on insulin resistance may be due to their effects on adipoR2.
authors: Disciplina de Fisiologia da Nutrição, Departamento de Fisiologia, Universidade Federal de São Paulo, São Paulo, Brazil. crioliva@uol.com.br
authors: Cristiane
authors: C
authors: de Oliveira
authors: Carla
authors: C
authors: Iwanaga-Carvalho
authors: João F
authors: JF
authors: Mota
authors: Lila M
authors: LM
authors: Oyama
authors: Eliane B
authors: EB
authors: Ribeiro
authors: Cláudia M
authors: CM
authors: Oller do Nascimento
mesh_terms: D041721:3T3-L1 Cells; D052242:Adiponectin / Q000235:genetics / Q000378:metabolism*; D000273:Adipose Tissue / Q000378:metabolism*; D000305:Adrenal Cortex Hormones / Q000378:metabolism*; D000315:Adrenalectomy; D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D015870:Gene Expression; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D015735:Mifepristone / Q000494:pharmacology; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D009132:Muscles / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D054419:Receptors, Adiponectin / Q000235:genetics / Q000378:metabolism*
chemical_list: D052242:Adiponectin; D000305:Adrenal Cortex Hormones; D054419:Receptors, Adiponectin; C504339:adiponectin receptor 1, rat; C506573:adiponectin receptor 2, rat; D015735:Mifepristone; D003907:Dexamethasone; D004837:Epinephrine