The Journal of Neuroscience, May 15, 2001, 21(10):3521-3530
Enhancement of Sensorimotor Behavioral Recovery in
Hemiparkinsonian Rats with Intrastriatal, Intranigral, and
Intrasubthalamic Nucleus Dopaminergic Transplants
K.
Mukhida,
K. A.
Baker,
D.
Sadi, and
I.
Mendez
Neural Transplantation Laboratory, Departments of Anatomy and
Neurobiology and Surgery (Division of Neurosurgery), Dalhousie
University, Halifax, Nova Scotia, Canada B3H 4H7
One of the critical variables that influences the efficacy of
clinical neural transplantation for Parkinson's disease (PD) is
optimal graft placement. The current transplantation paradigm that
focuses on ectopic placement of fetal grafts in the striatum (ST) fails
to reconstruct the basal ganglia circuitry or normalize neuronal
activity in important basal ganglia structures, such as the substantia
nigra (SN) and the subthalamic nucleus (STN). The aim of this study was
to investigate a multitarget neural transplantation strategy for PD by
assessing whether simultaneous dopaminergic transplants in the ST, SN,
and STN induce functional recovery in hemiparkinsonian rats. Forty-six
female Wistar rats with unilateral 6-hydroxydopamine lesions of the
nigrostriatal pathway were randomly divided into eight groups and
received lesions only or injections of 900,000 embryonic rat ventral
mesencephalic cells in the (1) ST, (2) SN, (3) STN, (4) ST and SN, (5)
ST, SN, and STN, (6) ST and STN, or (7) SN and STN. The number of cells transplanted was equally divided among grafting sites. Animals with two
grafts received 450,000 cells in each structure, and animals with three
grafts received 300,000 cells per structure. Recovery was assessed by
amphetamine-induced rotations and the stepping tests. Graft survival
was assessed using tyrosine hydroxylase immunohistochemistry. At 8 weeks after transplantation, simultaneous dopaminergic transplants in
the ST, SN, and STN induced significant improvement in rotational
behavior and stepping test scores. Intrastriatal transplants were
associated with significant recovery of rotational asymmetry, whereas
SN and STN transplants were associated with improved forelimb function
scores. These results suggest that restoration of dopaminergic activity
to multiple basal ganglia targets, such as the ST and SN, or the ST and
STN, promotes a more complete functional recovery of complex
sensorimotor behaviors. A multitarget transplant strategy aimed at
optimizing dopaminergic reinnervation of the basal ganglia may be
crucial in improving clinical outcomes in PD patients.
Key words:
subthalamic nucleus; dopamine; Parkinson's disease; neural transplantation; behavior; rat
Copyright © 2001 Society for Neuroscience 0270-6474/01/21103521-10$05.00/0