Serum IGF-I levels and IGF-I gene splicing in muscle of healthy young males receiving rhGH.
Growth Horm IGF Res
; 19(1): 61-7, 2009 Feb.
Article
em En
| MEDLINE
| ID: mdl-18799338
OBJECTIVE: Elevated growth hormone (GH) levels lead to increased circulating insulin-like growth factor-I (IGF-I), but the effects on localised muscle IGF-I splice variant expression is not known. The effects of rhGH administration, with or without an acute bout of high resistance exercise, were measured on serum IGF-I and on the mRNA levels of IGF-I splice variants in the vastus lateralis muscle of healthy young men. DESIGN: The study was a randomised double blind trial with a crossover design. Seven subjects were randomly assigned to a group receiving daily injections of rhGH (0.075IU kg(-1)day(-1)) or placebo for a two week period. Following a one month washout, the groups were reversed. RESULTS: Administration of rhGH increased circulating IGF-I from 31.8+/-3.2 to 109+/-5.4 nmol/L (p<0.05). There was no effect of the exercise bout. RNA was extracted from muscle biopsies obtained from exercised and non-exercised legs 2.5h after the cessation of the exercise. Transcript expression was measured using Real-time QPCR. There was no effect of either exercise or rhGH administration on IGF-I 5' (Class 1 or Class 2) or 3' (IGF-IEa, or MGF) transcripts. CONCLUSION: Although rhGH administration has an effect on liver IGF-I expression, as shown by increase in circulating IGF-I, muscle IGF-I expression is unaffected in young healthy subjects with normal GH profile. The findings contrast with those of a previous study in which GH deficient elderly men showed higher muscle IGF-I 3' splice variant levels following rhGH administration with and without resistance training. Unlike in the liver, muscle Class1 and 2 IGF-I expression do not change significantly following administration of rhGH.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fator de Crescimento Insulin-Like I
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Processamento Alternativo
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Músculo Esquelético
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Hormônio do Crescimento Humano
Tipo de estudo:
Clinical_trials
Limite:
Adult
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Humans
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Male
Idioma:
En
Revista:
Growth Horm IGF Res
Ano de publicação:
2009
Tipo de documento:
Article