Journal of Neuroscience, Vol 12, 2321-2330, Copyright © 1992 by Society for Neuroscience
Noradrenaline depletion blocks behavioral sparing and alters cortical morphogenesis after neonatal frontal cortex damage in rats
B Kolb and RJ Sutherland
Department of Psychology, University of Lethbridge, Alberta, Canada.
The possibility that cortical noradrenaline (NA) is necessary for sparing
of function that occurs after neonatal frontal cortex damage was examined.
Spatial localization by rats with frontal cortex damage on postnatal day 7
(P7) was better than that by rats with similar damage sustained as adults.
The sparing was abolished in rats depleted of cortical NA by means of
neonatal 6-hydroxydopamine (6HDA) administration. The blockade of sparing
in the P7 frontal operates was associated with a smaller brain, thinner
cortex, and reduced cortical dendritic branching relative to saline-treated
P7 frontal operates. NA depletion alone in unoperated rats did not affect
spatial learning but did reduce brain size and dendritic branching. Rats
with frontal lesions on P4 did not show sparing of spatial localization,
and 6HDA administration had no additional behavioral effect. Overall, these
data are consistent with the notion that NA has some general function in
maintaining some forms of plasticity in posterior cortex.