The cytoskeletal components of the myelin fraction are affected by a single intracranial injection of apotransferrin in young rats

We have previously shown that in rat pups intracranially injected with a si ngle dose of apotransferrin (aTf), there is an early oligodendroglial cell OLGc differentiation. The expression of the mRNAs of myelin basic proteins and of 2',3' cyclic nucleotide 3'-phosphodiesterase and the amount of the c orresponding proteins, as well as myelin glycolipids and phospholipids, wer e significantly increased in these animals at 10 and 17 days of age. Microt ubules and myelin basic proteins appear to be closely associated in OLGc an d it has been shown that the mRNAs of myelin basic proteins are concentrate d in the OLGc processes. The aim of this work was to clarify if the acceler ated myelination produced by aTf could be linked to changes in certain cyto skeletal elements present in the myelin fraction such as tubulin, actin, an d different microtubule-associated proteins (MAPs). A significant increase in the expression of the mRNA of tubulin and actin was observed in the brai n of the aTf-treated animals. Several MAPs, particularly MAP 1B and stable tubule only peptide as well as actin and tubulin, were markedly increased i n the Triton X-100 insoluble pellet obtained from the myelin fraction of th ese animals. The changes that we have previously described in the myelin of aTf intracranially injected rats, could be the consequence of its action o n the cytoskeletal network of the OLGc. An enlargement of this structure wo uld result in a more efficient and faster movement of the different compone nts that are normally transported to the myelin by the cytoskeleton of this cell.