Effects of GH and IGF-I administration on GHRH and somatostatin mRNA levels: I. A study on ad libitum fed and starved adult male rats.
J Endocrinol Invest
; 20(3): 144-50, 1997 Mar.
Article
em En
| MEDLINE
| ID: mdl-9186821
ABSTRACT
The individual role played by GH and IGF-I in the regulation of hypothalamic GHRH and SRIF gene expression is still object of debate. We have investigated the effect of exogenously administered recombinant hGH (rhGH) and recombinant hIGF-I (rhIGF-I) in ad libitum fed control and starved rats, the latter an animal model which is characterized by low circulating levels of endogenous GH and IGF-I. Adult male rats were fed ad libitum (C) or food-deprived (S) for 72 hours; rats in either C or S groups were treated with systemic administration of rhGH and rhIGF-I for 3 days. GHRH, SRIF and GH mRNA levels were evaluated by Northern and slot blot hybridization. Administration of rhGH (250 micrograms/kg/twice daily, sc) induced a significant inhibition of GHRH and a significant stimulation of SRIF mRNA levels in C rats; GH treatment was, however, ineffective on both neuropeptide mRNA levels in the S group. Continuous infusion of rhIGF-I (300 micrograms/kg/day, sc) induced a significant increase of SRIF levels in both C and S rats but did not modify GHRH mRNA levels in either group. In the pituitary, GH mRNA levels followed a pattern very similar to that of GHRH. These results provide evidence for a direct role of GH in the inhibition of GHRH mRNA levels; IGF-I appears more involved in the direct stimulation of SRIF mRNA levels.
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Base de dados:
MEDLINE
Assunto principal:
RNA Mensageiro
/
Fator de Crescimento Insulin-Like I
/
Somatostatina
/
Hormônio Liberador de Hormônio do Crescimento
/
Hormônio do Crescimento Humano
/
Privação de Alimentos
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
J Endocrinol Invest
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Itália