title: Improved outcome of facial nerve repair in rats is associated with enhanced regenerative response of motoneurons and augmented neocortical plasticity.
abstract: Within a recent study on the vibrissae motor performance after facial nerve repair in strains of blind (SD/RCS) and sighted (SD) rats we found that, despite persisting myotopic disorganization in the facial nucleus, the blind animals fully restored vibrissal whisking. Here we searched for morphological substrates of better recovery in the regenerating motoneurons and in the cerebral motor cortex. Expression analyses of the neurite growth-related proteins f-actin, neuronal class III beta-tubulin and plasticity-related gene-1, and stereological estimates of growth cone densities revealed a more vigorous regenerative response in the proximal nerve stump of blind SD/RCS rats compared with SD animals at 5-7 days after buccal nerve transection. Using c-Fos immunoreactivity as a marker for neuronal activation, we found that the volume of the cortex acutely responding to nerve transection (facial muscles reactive volume, FMRV) in both hemispheres of intact sighted rats was twofold smaller than that measured in blind animals. One month after transection and suture of the right facial nerve (FFA) we found a twofold increase in the FMRV in both rat strains compared with intact animals. The FMRV in SD/RCS animals, but not in SD rats, returned to the values in intact rats 2 months after FFA. Our findings suggest that enhanced plasticity in the CNS and an augmented regenerative response of the injured motoneurons contribute to better functional recovery in blind rats.
authors.affiliation: Department of Anatomy I, University of Cologne, Germany.
authors.forename: Gergana P
authors.initials: GP
authors.lastname: Peeva
authors.forename: Srebrina K
authors.initials: SK
authors.lastname: Angelova
authors.forename: Orlando
authors.initials: O
authors.lastname: Guntinas-Lichius
authors.forename: Michael
authors.initials: M
authors.lastname: Streppel
authors.forename: Andrey
authors.initials: A
authors.lastname: Irintchev
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schütz
authors.forename: Anastas
authors.initials: A
authors.lastname: Popratiloff
authors.forename: Nicolai E
authors.initials: NE
authors.lastname: Savaskan
authors.forename: Anja U
authors.initials: AU
authors.lastname: Bräuer
authors.forename: Athanasia
authors.initials: A
authors.lastname: Alvanou
authors.forename: Robert
authors.initials: R
authors.lastname: Nitsch
authors.forename: Doychin N
authors.initials: DN
authors.lastname: Angelov
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001369:Axons / Q000502:physiology; D001766:Blindness / Q000503:physiopathology; D015153:Blotting, Western; D003627:Data Interpretation, Statistical; D005154:Facial Nerve / Q000502:physiology*; D016762:Genes, fos / Q000187:drug effects; D020439:Growth Cones / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D009044:Motor Cortex / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology*; D019579:Neocortex / Q000166:cytology / Q000502:physiology*; D009416:Nerve Regeneration / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014404:Tubulin / Q000096:biosynthesis; D015854:Up-Regulation / Q000502:physiology; D014738:Vibrissae / Q000294:innervation / Q000502:physiology
chemical_list: D000199:Actins; D009419:Nerve Tissue Proteins; D014404:Tubulin