Expression of insulin-like growth factor-I (IGF-I) and IGF-II in the avian brain: relationship of in situ hybridization patterns with IGF type 1 receptor expression.
Int J Dev Neurosci
; 18(1): 69-82, 2000 Feb.
Article
en En
| MEDLINE
| ID: mdl-10708908
ABSTRACT
Insulin-like growth factors (IGFs) are expressed in defined spatiotemporal patterns during the development of the mammalian central nervous system (CNS). Since IGF expression in avian species is less well documented, we studied here the expression of IGF-I and IGF-II during chicken CNS development, using in situ hybridization and reverse transcriptase-PCR, and compared the results with the expression of the IGF type 1 receptor (IGF-1R). IGF-II expression started early in embryonic life, shortly after the onset of IGF-1R expression. During organogenesis, IGF-II was strongly expressed in kidney, liver and gut primordia, in contrast with IGF-1R mRNA, which is highly enriched in proliferating neuroepithelia. During the second half of embryonic development, IGF-I and IGF-II had distinct expression patterns, suggesting specific roles for each ligand during brain maturation. IGF-II mRNA was found in numerous brainstem nuclei and in the optic tectum, whereas IGF-I mRNA was found predominantly in telencephalic regions. Both ligands were expressed in the cerebellum, but each by different cell layers. Some brain regions (olfactory bulb and olivo-cerebellar system) did not exhibit the postnatal downregulation typical of extrahepatic IGF-I expression, but continued to express IGF-I into adulthood. Purkinje cells expressed IGF-II in the embryo, but switched to IGF-I expression in the adult. The conservation of embryonic and postnatal IGF expression patterns in the CNS between avians and mammals suggests that the involvement of the IGF system in neurogenesis and differentiation, and possibly in neural plasticity and learning, may have arisen early during tetrapode/vertebrate evolution.
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Bases de datos:
MEDLINE
Asunto principal:
Encéfalo
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Química Encefálica
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Factor I del Crecimiento Similar a la Insulina
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Factor II del Crecimiento Similar a la Insulina
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Regulación del Desarrollo de la Expresión Génica
Límite:
Animals
Idioma:
En
Revista:
Int J Dev Neurosci
Año:
2000
Tipo del documento:
Article
País de afiliación:
Francia