CONICET | Buscador de Institutos y Recursos Humanos

Mechanisms that control oligodendroglial cell (OLGc) differentiation are the focus of intensive research in molecular neurobiology. However, the physiological relevance of proteinglycan interactions in this process is still uncertain. Our previous results showed that galectin-3 is up-regulated upon maturation in OLGc primary cultures. Consistently, treatment with recombinant galectin-3 promotes OLGc maturation as shown by the increased number of myelin-basic protein (MBP) positive cells and a decrease in A2B5-positive oligodendrocyte progenitors. Participation of galectin-3 in the myelination process was investigated. For this purpose we used Gal-3 KO and WT mice at 4 and 8 weeks of age. Myelination was evaluated by electron microscopy and immunohistochemistry, and by Western blots. KO mice were significantly demyeliniated as compared to controls. On corpus callosum and striatum sections, large patches appeared without any stainable myelin surrounded by weakly stained myelinated axons. Accordingly, myelin basic protein (MBP) and RIP showed a decresed immunoreactivity in the experimental animals compared to controls. Results on Western blots of MBP are in close agreement with those obtained by immunohistochemistry. EM shows that the most common lesion in axons of Gal-3 -/- mice was the detachment of the axon from the inner myelin lamella with areas of axonal collapse surrounded by myelin sheaths of abnormal morphology. The parameters that were submitted to a quantitative evaluation were a) total number of myelinated axons b) width of myelin in different axons and c) ratio of diameter of an axon over the diameter of axon plus associated myelin sheath. The abnormalities in myelin and in myelinated axons were present in 4 and 8-week old animals.