The Journal of Neuroscience, August 15, 2001, 21(16):6252-6263
Restorative Plasticity of Dopamine Neuronal Transplants
Depends on the Degree of Hemispheric Dominance
Guido
Nikkhah,
Gero
Falkenstein, and
Christoph
Rosenthal
Neurosurgical Clinic, Nordstadt Hospital, D-30167 Hannover,
Germany
The ability of dopaminergic (DA) transplants to restore complex
sensorimotor behaviors in experimental Parkinson's disease is
dependent on graft survival and reinnervation and is likely to be
further modified by complex functional graft-host interactions. Here,
we examined the impact of hemispheric dominance and extensive testing
regimes on the functional capabilities of DA transplants to restore
skilled forelimb movements in rats with unilateral 6-hydroxydopamine
lesions. Interestingly, a near complete recovery was observed in
DA-grafted animals that did not exhibit a strong hemispheric
lateralization for paw use before lesion and implantation surgery,
whereas animals with a clear lateralization of paw use and
grafted into the contralateral hemisphere exhibited only
moderate recovery. Finally, animals grafted ipsilateral to the
preferred paw were most resistant to functional improvements in skilled forelimb use. However, the influence of hemispheric dominance on the
degree of functional DA graft-induced restoration was specific for
skilled forelimb use, whereas no such differences were observed in
other tests for motor and sensory functions related to the DA system.
Furthermore, functional recovery of DA-grafted animals in skilled
forelimb use was significantly promoted by extensive behavioral testing
regimes indicative of a "learning how to use" the transplant effect.
These findings indicate the importance of the underlying functional
architecture of complex sensorimotor behaviors, such as skilled
forelimb use, and the DA neurotransmitter system for the plasticity of
DA transplants to promoting a more complete behavioral recovery
in experimental, and potentially, also in clinical forms of
Parkinson's disease.
Key words:
Parkinson's disease; 6-hydroxydopamine; skilled forelimb
use; stepping; sensorimotor behavior; nigrostriatal dopamine system; hemispheric lateralization
Copyright © 2001 Society for Neuroscience 0270-6474/01/21166252-12$05.00/0