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Bergmann glial ensheathment of dendritic spines regulates synapse number without affecting spine motility

Published online by Cambridge University Press:  02 November 2010

Jocelyn J. Lippman Bell
Affiliation:
Department of Neuroscience, Brown University, Providence, RI, USA
Tamar Lordkipanidze
Affiliation:
Department of Neuroscience, Brown University, Providence, RI, USA
Natalie Cobb
Affiliation:
Department of Neuroscience, Brown University, Providence, RI, USA
Anna Dunaevsky*
Affiliation:
Department of Neuroscience, Brown University, Providence, RI, USA
*
Correspondence should be addressed to: Anna Dunaevsky, Developmental Neuroscience Department, Munroe-Meyer Institute, University of Nebraska Medical Center, 985960 Nebraska Medical Center, Omaha, NE 68198-5960USA email: adunaevsky@unmc.edu

Abstract

In the cerebellum, lamellar Bergmann glial (BG) appendages wrap tightly around almost every Purkinje cell dendritic spine. The function of this glial ensheathment of spines is not entirely understood. The development of ensheathment begins near the onset of synaptogenesis, when motility of both BG processes and dendritic spines are high. By the end of the synaptogenic period, ensheathment is complete and motility of the BG processes decreases, correlating with the decreased motility of dendritic spines. We therefore have hypothesized that ensheathment is intimately involved in capping synaptogenesis, possibly by stabilizing synapses. To test this hypothesis, we misexpressed GluR2 in an adenoviral vector in BG towards the end of the synaptogenic period, rendering the BG α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) Ca2+-impermeable and causing glial sheath retraction. We then measured the resulting spine motility, spine density and synapse number. Although we found that decreasing ensheathment at this time does not alter spine motility, we did find a significant increase in both synaptic pucta and dendritic spine density. These results indicate that consistent spine coverage by BG in the cerebellum is not necessary for stabilization of spine dynamics, but is very important in the regulation of synapse number.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2010

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Footnotes

*

Current address: Department of Neurology, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA.

Current address: Developmental Neuroscience Department, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA.

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