The Journal of Neuroscience, July 1, 1999, 19(13):5563-5573
Diminished Viability, Growth, and Behavioral Efficacy of Fetal
Dopamine Neuron Grafts in Aging Rats with Long-Term Dopamine Depletion:
An Argument for Neurotrophic Supplementation
Timothy J.
Collier,
Caryl E.
Sortwell, and
Brian F.
Daley
Department of Neurological Sciences and Research Center for Brain
Repair, Rush Presbyterian-St. Luke's Medical Center, Chicago, Illinois
60612
We examined the behavioral and morphological correlates of the
response to a single intrastriatal dispersed cell graft of fetal rat
ventral mesencephalic tissue in male Fischer-344 rats of varying age
(4, 17, and 24-26 months old) and history of mesostriatal dopamine
(DA) depletion (1 or 14 months). Our goal was to determine the impact
of advancing age and duration of DA depletion in the host on DA graft
viability and function. The findings can be summarized as follows. (1)
Fetal DA neuron grafts that were effective in completely ameliorating
amphetamine-induced rotational behavior in young rats with short-term
lesions were virtually without effect in aged rats with long-term
lesions. Middle-aged rats with long-term lesions responded to these
grafts with partial behavioral recovery. (2) Age of the host at the
time of transplantation, and not duration of DA depletion, was the
primary determinant of response to DA grafts. (3) Diminished efficacy
of grafts in lesioned aging rats was related to decreased survival and
neurite extension of transplanted DA neurons. (4) Co-grafts of DA
neurons with Schwann cells as a source of neurotrophic support improved
the behavioral outcome of grafts in aged lesioned rats. These findings
support the view that the DA-depleted striatum of aged rats is an
impoverished environment for survival, growth, and function of DA
grafts. Consistent with this view, local supplementation of the
neurotrophic environment of grafted DA neurons with products of
co-grafted Schwann cells, a demonstrated source of neurotrophic
activity for embryonic DA neurons, improved graft outcome.
Key words:
dopamine; fetal; transplant; graft; aging; neurotrophic; long-term lesion; co-graft; Schwann cells; Parkinson's disease; rotational behavior; amphetamine; striatum
Copyright © 1999 Society for Neuroscience 0270-6474/99/19135563-11$05.00/0