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pubmed:abstractText |
Bergmann glial cells are specialized astrocytes in the cerebellum. In the mature cerebellar molecular layer, Bergmann glial processes are closely associated with Purkinje cells, enclosing Purkinje cell dendritic synapses with a glial sheath. There is intensive gap junctional coupling between Bergmann glial processes, but their significance in cerebellar functions is not known. Connexin43 (Cx43), a major component of astrocytic gap junction channels, is abundantly expressed in Bergmann glial cells. To examine the role of Cx43-mediated gap junctions between Bergmann glial cells in cerebellar functions, we generated Cx43 conditional knockout mice with the S100b-Cre transgenic line (Cx43(fl/fl):S100b-Cre), which exhibited a significant loss of Cx43 in the Bergmann glial cells and astrocytes in the cerebellum with a postnatal onset. The Cx43(fl/fl):S100b-Cre mice had normal cerebellar architecture. Although gap junctional coupling between the Bergmann glial cells measured by spreading of microinjected Lucifer yellow was virtually abolished in Cx43(fl/fl):S100b-Cre mice, electrophysiologic analysis revealed that cerebellar long-term depression could be induced and maintained normally in their cerebellar slices. In addition, at the behavioral level, Cx43(fl/fl):S100b-Cre mice had normal motor coordination in the rotarod task and normal conditioned eyelid response. Our findings suggest that Cx43-mediated gap junctional coupling between Bergmann glial cells is not necessary for the neuron-glia interactions required for cerebellum-dependent motor coordination and motor learning.
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