Expression of insulin‐like growth factors in remyelination following ethidium bromide‐induced demyelination in the mouse spinal cord

Abstract

Insulin-like growth factors, IGF-I and IGF-II, play important roles in development and myelination in the CNS, but little is known about the response of IGF after demyelination. The present study investigated the expression of IGF and their cognitive receptors in the process of remyelination following ethidium bromide (EBr)-induced demyelination in the adult mouse spinal cord. The present results, in a quantitative real-time PCR, showed significant increases in the levels of the mRNA for both IGF-I and IGF-II during both the demyelination and remyelination stages. The levels of IGF-I receptor (IGF-IR) mRNA increased from 10 days to 4 weeks after the EBr injection. The levels of IGF-II receptor (IGF-IIR) mRNA decreased for 6 days and then increased 10 days after the EBr injection. In situ hybridization studies showed the cells expressing IGF-I mRNA to be mainly macrophage-like cells, while those expressing IGF-II mRNA were predominantly Schwann cell-like cells invading the demyelinating lesion. The immunoreactivity for the IGF-IR and IGF-IIR increased in various kinds of cells within and around the demyelinating lesions from 6 days to 4 weeks after the EBr injection. These results suggest that locally produced IGF could partly be involved in some mechanisms underlying remyelination processes following the EBr-induced demyelination in the mouse spinal cord.

The Insulin-Like Growth Factor (IGF) Receptor Type 1 (IGF1R) as an Essential Component of the Signalling Network Regulating Neurogenesis

“…IGF-I, produced locally or delivered to the CNS from the circulation, induces a constitutive level of IGF1R-mediated signalling in the adult CNS, which is important for brain functions and adult neurogenesis [68]. This level can increase in response to a pathological process in the CNS [69] or as a result of adaptive response to exercise and correlates with increased hippocampal neurogenesis [70]. Secretion of IGF1R ligands in organising centres or its expression in a graded manner is not characteristic for the developing mammalian CNS whose patterning, by contrast to the neurogenesis in Xenopus laevis [71][72][73], is not known to depend on IGF1R activation.…”

From blood to brain: amoeboid microglial cell, a nascent macrophage and its functions in developing brain

“…In the developing white matter, AMC have also been reported to function as guides for developing axons, perhaps through the manufacture of extracellular matrix molecules, such as thrombospondin [49,50] . Insulin-like growth factors Insulin-like growth factor (IGF) I and II are known to regulate the development of the nervous system [51] . IGF-I plays an important role in promoting cell proliferation and differentiation [52] in the devel-oping brain.…”

Administration of vitamin D 3 induces CNPase and myelin oligodendrocyte glycoprotein expression in the cerebral cortex of the murine model of cuprizone-induced demyelination

“…Several studies have shown a role of antibodies against MOG in the pathogenesis of MS [10]. Growth factors including insulin like growth factor were shown to be important in repair processes of demyelination [12]. Ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) have been shown to have an important role in the process of remyelination by increasing Opalin (34 KDa) and MOG expression [23,29].…”