title: Lack of Connexin43-mediated bergmann glial gap junctional coupling does not affect cerebellar long-term depression, motor coordination, or eyeblink conditioning.
abstract: 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.
authors.affiliation: RIKEN Brain Science Institute (BSI) Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Tanaka
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Tatsukawa
authors.forename: Chieko
authors.initials: C
authors.lastname: Nishioka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishiyama
authors.forename: Martin
authors.initials: M
authors.lastname: Theis
authors.forename: Klaus
authors.initials: K
authors.lastname: Willecke
authors.forename: Shigeyoshi
authors.initials: S
authors.lastname: Itohara