Journal of Neuroscience, Vol 2, 394-398, Copyright © 1982 by Society for Neuroscience
Specific uptake of norepinephrine and dopamine by homogenates of rat cerebral cortex after locus ceruleus lesion
WJ Logan and SI Harik
Unilateral injection of 6-hydroxydopamine into the locus ceruleus led to
long lasting depletion of norepinephrine in the ipsilateral parietal
cerebral cortex of the rat up to 8 weeks after injection. The uptake of
both norepinephrine and dopamine by homogenates of parietal cortex was
decreased markedly on the ipsilateral, but not on the contralateral, side.
The uptake of four other neurotransmitter candidates or precursors was
unaffected by the lesion. Desipramine (DMI) markedly inhibited the uptake
of both norepinephrine and dopamine by cortical preparations from the
contralateral side and from control rats, but this effect was not seen in
preparations from the norepinephrine- depleted, ipsilateral cortex. The
decreases DMI-sensitive uptake of norepinephrine or dopamine was highly
correlated with decreased norepinephrine in the ipsilateral cortex. These
results suggest that the specific uptake of norepinephrine and dopamine is
a valid marker of noradrenergic innervation of the parietal cortex and that
dopamine seems to be accumulated primarily by norepinephrine terminals in
this region. Two and 8 weeks after locus ceruleus lesion, a
DMI-insensitive, benztropine-sensitive dopamine uptake becomes apparent in
ipsilateral cortical preparations, This may represent proliferation or
increased function of dopaminergic cortical projections, compensating for
noradrenergic denervation.