Restricted occurrence of an unusual ganglioside GD1 alpha in rat brain and its possible involvement in dendritic growth of cerebellar Purkinje neurons.

The spatial pattern of expression of a minor disialosyl ganglioside GD1 alpha in the rat brain was investigated immunohistochemically using a specific murine monoclonal antibody KA-17. The antibody shows noticeable immunoreactivity in the proximal dendrites and neuronal cell bodies of restricted populations of neurons including cerebral pyramidal neurons and cerebellar Purkinje neurons. Immunocytochemical analysis revealed that Purkinje neurons maintained in a dissociate culture condition also express GD1 alpha in the dendrites and cell bodies. We have examined the functional involvement of this ganglioside in the growth of brain neurons using KA-17 antibody. Addition of the antibody to cerebellar primary cultures caused perturbation of the dendritic development of Purkinje neurons in a dose-dependent manner. The length and branching of the dendrites were severely decreased by the antibody treatment. When other anti-glycoconjugate or sphingolipid monoclonal antibodies were tested, only HNK-1 monoclonal antibody that recognizes sulfoglucuronic residues in glycolipids and glycoproteins had similar but moderate inhibitory actions on the dendritic development of these neurons. In contrast to the morphological alterations observed in Purkinje cells, other cerebellar cells including granule neurons appear to be almost normal following the antibody treatment. These observations lead to the possibility that GD1 alpha ganglioside has a role in the development of Purkinje cell dendrites.