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  • 1
    ISSN: 1432-1106
    Keywords: Substantia nigra ; Neuronal transplantation ; Trophic Factors ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Embryonic substantia nigra cells when transplanted into the striatum can reverse many of the defects of Parkinson's disease. The efficacy of such grafts is compromised by the poor survival of grafted dopaminergic neurones; typically, 3–10% survive transplantation. We used three tissue culture models to identify stages in the procedure for the preparation and insertion of grafts which might be responsible for this cell death and to identify environments in which survival is optimised. (1) The ventral mesencephalon was dissected from the donor brain, then placed immediately into culture contained in a collagen gel. (2) The dissected tissue fragments were enzymatically dissociated, then the cells placed into monolayer culture. (3) Enzymatically dissociated tissue was packed into 0.5-mm-diameter porous tubes, to simulate the compaction of cells into a graft deposit in the host brain. Dissociation of the tissue by itself caused the death of approximately 30% of dopaminergic neurones, as judged by the difference in cell counts between the intact embryonic day 14 (E14) mesencephalon, and cells dissociated then packed into tubes. Of the dissociated neurones approximately 60% died during the first 24 h and 87% during the first 3 days in monolayer culture, while only 7% of dopaminergic neurones in three-dimensional cultures and 11% of neurones in explant cultures died over the first 3 days. Embryonic dopaminergic neurones are clearly very vulnerable to adverse conditions during the first days after their removal from the donor brain. The excellent survival of neurones in three-dimensional and explant cultures indicates that close association with other cells, which may provide greatly improved access to trophic factors, can enable the cells to survive this period of vulnerability. In contrast to its effects in monolayer cultures, bFGF had no effect on dopaminergic neuronal survival in either explant or three-dimensional cultures.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 87 (1985), S. 357-363 
    ISSN: 1432-2072
    Keywords: Delayed matching ; Short-term memory ; Cholinergic systems ; Nucleus basalis ; Fimbria-fornix ; Scopolamine ; Physostigmine ; Methamphetamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To provide a more specific test of memory impairments following lesions to central cholinergic systems, rats were trained on an operant delayed matching task. Ibotenic acid lesions of the nucleus basalis produced a disruption of performance at all delay intervals (a parallel downward shift in the delay-performance curve). By contrast, fimbriafornix transections had no effects at short delays, but produced a progressively greater impairment as the delays lengthened (an increased downward slope of the delay-performance curve). Scopolamine produced a dose-dependent disruption of performance, apparent at the shortest delays but greater at longer delays, that was similar to the two lesion deficits combined, whereas physostigmine induced a mild but significant enhancement of performance. The results support the hypothesis that disruption of hippocampal circuitries, including cholinergic afferents via the fimbria-fornix, produces short-term or working memory impairments, whereas disruption of the cortical cholinergic system implicates more stable long-term aspects of task performance. Peripherally administered cholinergic drugs produce both types of effect and thus may influence both systems.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 101 (1994), S. 365-374 
    ISSN: 1432-1106
    Keywords: 6-Hydroxydopamine ; Ibotenic acid ; Rotation ; Amphetamine ; Apomorphine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Lesions of the dopaminergic nigrostriatal tract produce a range of motor and sensorimotor deficits. One of the simplest and most reliable is the rotational response of the animal following activation with drugs that stimulate the dopaminergic network, most notably amphetamine and apomorphine. Consequently, the rotation test has been extensively used in assessing the success of treatments designed to restore dopaminergic function, including neural transplants. The present study investigates whether rotation induced by 6-hydroxydopamine lesions of the nigrostriatal bundle in rats is modified by additional lesions in the neostriatum. It was found that apomorphine-induced rotation can be reduced by ibotenic acid lesions of the dopamine-deafferented striatum, and that the extent of the reduction was proportional to the size of the lesions. In contrast, such lesions produced a non-significant reduction in amphetamine-induced rotation, although the correlation between the extent of the reduction and the size of the lesion was again apparent. Since the pattern of change was similar in direction, albeit smaller in magnitude, than the previously reported effects of intrastriatal transplantation in rats with similar nigrostriatal lesions, rotation tests alone do not provide an unequivocal test of graft survival and function.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1106
    Keywords: Neural transplantation ; Parkinson's disease ; Tissue cultures ; Mesencephalon ; Human embryo ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Free-floating roller tube cultures of human fetal (embryonic age 6–10 weeks post-conception) and rat fetal (embryonic day 13) ventral mesencephalon were prepared. After 7–15 days in vitro, the mesencephalic tissue cultures were transplanted into the striatum of adult rats that had received unilateral injections of 6-hydroxydopamine into the nigrostriatal bundle 3–5 weeks prior to transplantation. Graft survival was assessed in tyrosine hydroxylase (TH)-immunostained serial sections of the grafted brains up to post-transplantation week 4 for the human fetal xenografts and post-transplantation week 11 for the rat fetal allografts. d-amphetamine-induced rotation was monitored up to 10 weeks after transplantation in the allografted animals and compared with that of lesioned-only control animals. All transplanted animals showed large, viable grafts containing TH-immunoreactive (ir) neurons. The density of TH-ir neurons in the human fetal xenografts and in rat fetal allografts was similar. A significant amelioration of the amphetamine-induced rotation was observed in the animals that received cultured tissue allografts. These results promote the feasibility of in vitro maintenance of fetal human and rat nigral tissue prior to transplantation using the free-floating roller tube technique.
    Type of Medium: Electronic Resource
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