Journal of Neuroscience, Vol 12, 1001-1009, Copyright © 1992 by Society for Neuroscience
Rapid and reversible astrocytic reaction to afferent activity blockade in chick cochlear nucleus
KS Canady and EW Rubel
Hearing Development Laboratory, University of Washington, Seattle 98195.
We describe here rapid proliferation of astrocytic processes immunoreactive
for glial fibrillary acidic protein (GFAP) in the chick cochlear nucleus
following blockade of action potentials in the afferent nerve. Unilateral
eighth nerve activity blockade was achieved through intralabyrinthine
injection of TTX. Within 1 hr of activity blockade, a 56% increase in area
density of GFAP-immunoreactive processes was found in the ipsilateral
cochlear nucleus as compared to the contralateral side of the brain. This
increase reached 152% by 3 hr. When eighth nerve activity was allowed to
recover and animals were studied 1 week after TTX injection, no difference
was found in GFAP immunoreactivity between the ipsilateral and
contralateral cochlear nuclei. This is the first report of a glial reaction
to documented neuronal inactivity in the absence of neuropathology. These
results indicate that neuronal activity may regulate the structure of
astrocytic processes.