The Role of IGF-I in Cerebellar Granule Cell Survival and Terminal Differentiation
Insulin-like growth factor (IGF) I is a pleiotropic agent for the survival and differentiation of different types of nerve cells during development . IGF-I over- expression in transgenic mice induces a marked increase in size and number of neurones in most cerebral areas . The most thorough studies on IGF-I action within the context of brain are those performed in the last decade on cerebellar neuronal populations. In cerebellum, this somatomedin, its receptor and its specific binding proteins are developmentally expressed in such a fashion as to suggest a crucial role in circuit formation [3, 4]. Similar functions have been previously demonstrated or hypothesised for nerve growth factor (NGF) and other growth factors of the neurotrophin family. The action of neuronal growth factors may be exerted either via retrograde transport from target cells to the perikarion of the innervating neuron or, vice versa, via orthograde transport from the innervating neuron to the target cells . The best characterized example of the former case is represented by NGF , while IGF-I displays the second type of trophic interaction with target cells .
KeywordsNerve Growth Factor Conditioned Medium Glutamate Receptor Terminal Differentiation Cerebellar Granule Cell
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