Molecular and Cellular Substrates for the Friedreich Ataxia. Significance of Contactin Expression and of Antioxidant Administration

This study explores the neural phenotype in rodent models of the spinocerebellar disorder Friedreich Ataxia (FA). The M12 mouse line, bearing a mutation that disrupts the Frataxin gene exon 4 was used, together with the M02 line, which, in addition, is hemizygous for the human Frataxin gene carrying 82-190 GAA repeats within its first intron (Pook transgene). The mutant mice phenotype was compared to the one of wild type littermates in regions undergoing differential profiles of neurogenesis, including the cerebellar cortex and the spinal cord by using neuronal (β-tubulin) and glial (Glial Fibrillary Acidic Protein) markers as well as the Contactin 1 axonal glycoprotein, involved in neurite growth control. Morphological/morphometric analyses revealed that in Frataxin mutant mice a reduction of β-tubulin immunostaining was observed, together with glial upregulation. Furthermore, Contactin 1 downregulation suggested that changes in the expression of this gene contributed to the pathogenesis. Therefore, the FA phenotype implies an alteration of the developmental profile of neuronal and glial precursors. Finally, epigallocatechin gallate polyphenol administration counteracted the disorder, indicating protective effects of antioxidant administration.

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