Volume 16, Number 21,
Issue of November 1, 1996
pp. 6965-6974
Copyright ©1996 Society for Neuroscience
Constructing a New Nigrostriatal Pathway in the Parkinsonian
Model with Bridged Neural Transplantation in Substantia Nigra
Received May 14, 1996; revised Aug. 2, 1996; accepted Aug. 12, 1996.
Feng C. Zhou1,
Yung H. Chiang1, and
Yun Wang2
1 Department of Anatomy and Medical Neurobiology
Program, Indiana University School of Medicine, Indianapolis, Indiana
46202, and 2 Department of Pharmacology, National Defense
Medical Center, Taipei, Taiwan
The physical repair and restoration of a completely damaged pathway
in the brain has not been achieved previously. In a previous study,
using excitatory amino acid bridging and fetal neural transplantation,
we demonstrated that a bridged mesencephalic transplant in the
substantia nigra generated an artificial nerve pathway that
reinnervated the striatum of 6-hydroxydopamine (6-OHDA)-lesioned rats.
In the current study, we report that a bridged mesencephalic transplant
can anatomically, neurochemically, and functionally reinstate the
6-OHDA-eradicated nigro-striatal pathway. An excitatory amino acid,
kainic acid, laid down in a track during the transplant generated a
trophic environment that effectively guided the robust growth of
transplanted neuronal fibers in a bundle to innervate the distal
striatum. Growth occurred at the remarkable speed of ~200 µm/d. Two
separate and distinct types of dopamine (DA) innervation from the
transplant have been achieved for the first time: (1) DA innervation of
the striatum, and (2) DA innervation of the pars reticularis of the
substantia nigra. In addition, neuronal tracing revealed that
reciprocal connections were achieved. The grafted DA neurons in the SNr
innervated the host's striatum, whereas the host's striatal neurons,
in turn, innervated the graft within 3-8 weeks. Electrochemical volt-
ammetry recording revealed the restoration of DA release and
clearance in a broad striatal area associated with the DA
reinnervation. Furthermore, the amphetamine-induced rotation was
attenuated, which indicates that the artificial pathways were motor
functional. This study provides additional evidences that our bridged
transplantation technique is a potential means for the repair of a
completely damaged neuronal pathway.
Key words:
excitatory amino acid;
neural transplant;
dopamine;
pathway repair;
voltammetry;
HRP/immunocytochemistry double staining;
rotational behavior