Journal of Neuroscience, Vol 13, 3864-3877, Copyright © 1993 by Society for Neuroscience
Adrenal medulla grafts in the hemiparkinsonian rat: profile of behavioral recovery predicts restoration of the symmetry between the two striata in measures of pre- and postsynaptic dopamine function
EJ Curran, RL Albin and JB Becker
Neuroscience Program, University of Michigan, Ann Arbor 48104-1687.
Following unilateral striatal dopamine depletion, the hemiparkinsonian rat
exhibits rotational behavior in response to amphetamine and apomorphine.
The rotational behaviors induced by these drugs are thought to reflect an
asymmetry in presynaptic striatal dopamine release and an asymmetry in
postsynaptic striatal dopamine receptor function, respectively. Grafts of
adrenal medulla cells in the lateral ventricle of hemiparkinsonian rats
have been reported to reduce behavioral asymmetry. More than one profile of
behavioral recovery, however, is observed. Some animals show a
graft-induced decrease only in the response to apomorphine, but others show
a decrease in the response to amphetamine, and still others show a decrease
in the behavioral responses to amphetamine and apomorphine. In this report,
amphetamine- and apomorphine-induced turning behaviors were determined in
hemiparkinsonian rats prior to and following intraventricular grafts of
adrenal medulla or control tissue. Both bilateral intrastriatal
microdialysis in freely moving animals and quantitative dopamine receptor
autoradiography procedures were conducted in each animal so as to determine
the relations between pre- and postsynaptic dopaminergic measures as well
as the association between these measures and the different profiles of
behavioral recovery after adrenal medulla grafts. We report here that in
animals with an adrenal medulla graft-induced decrease in the behavioral
response to amphetamine, the balance between the two striata in
extracellular striatal dopamine concentrations and D2 dopamine receptor
binding was restored. Furthermore, enhanced extracellular striatal dopamine
concentrations were highly correlated with the graft-induced symmetry in
striatal D2 dopamine receptor binding. In contrast to animals with
decreased amphetamine-induced turning, in animals with a graft-induced
decrease exclusively in response to apomorphine, the presynaptic symmetry
was not restored and there was a significantly smaller effect on D2
receptor binding. We conclude that those animals that show decreased
amphetamine-induced turning after adrenal medulla grafts had the most
effective grafts, and suggest that methods designed to optimize this
behavioral profile are most likely to lead to enhanced clinical efficacy
with this procedure.