Borna disease virus infection alters synaptic input of neurons in rat dentate gyrus.
Granule cells are major targets of entorhinal afferents terminating in a laminar fashion in the outer molecular layer of the dentate gyrus. Since Borna disease virus (BDV) infection of newborn rats causes a progressive loss of granule cells in the dentate gyrus, entorhinal fibres become disjoined from their main targets. We have investigated the extent to which entorhinal axons react to this loss of granule cells. Unexpectedly, anterograde DiI tracing has shown a prominent layered termination of the entorhinal projection, despite an almost complete loss of granule cells at 9 weeks after infection. Combined light- and electron-microscopic analysis of dendrites at the outer molecular layer of the dentate gyrus at 6 and 9 weeks post-infection has revealed a transient increase in the synaptic density of calbindin-positive granule cells and parvalbuminergic neurons after 6 weeks. In contrast, synaptic density reaches values similar to those of uninfected controls 9 weeks post-infection. These findings indicate that, after BDV infection, synaptic reorganization processes occur at peripheral dendrites of the remaining granule cells and parvalbuminergic neurons, including the unexpected persistence of entorhinal axons in the absence of their main targets.
Heimrich
Bernd
B
Institute of Anatomy and Cell Biology, Department of Neuroanatomy, University of Freiburg, Freiburg, Germany. bernd.heimrich@zfn.uni-freiburg.de
Hesse
Daniel-Alexander
DA
Wu
Yuan-Ju
YJ
Schmid
Sonja
S
Schwemmle
Martin
M
D000344:Afferent Pathways; D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D001890:Borna Disease / Q000473:pathology* / Q000503:physiopathology; D001891:Borna disease virus; D064026:Calbindins; D003712:Dendrites / Q000502:physiology / Q000648:ultrastructure; D018891:Dentate Gyrus / Q000473:pathology; D018728:Entorhinal Cortex / Q000473:pathology*; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure / Q000821:virology; D010320:Parvalbumins / Q000378:metabolism; D051381:Rats; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D013569:Synapses / Q000502:physiology / Q000648:ultrastructure / Q000821:virology*
D064026:Calbindins; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G