INDUCED HOMOTYPIC SPROUTING OF SEROTONERGIC RAPHE-HIPPOCAMPAL SYSTEM AND ITS REGULATION BY CORTICOSTERONE.
Item
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Title
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INDUCED HOMOTYPIC SPROUTING OF SEROTONERGIC RAPHE-HIPPOCAMPAL SYSTEM AND ITS REGULATION BY CORTICOSTERONE.
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Identifier
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AAI8401967
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identifier
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8401967
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Creator
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ZHOU, FENG CHIAO SIMON.
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Contributor
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Dr. Efrain C. Azmitia
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Date
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1983
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Anatomy
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Abstract
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Most studies of neuronal plasticity have concentrated on regeneration or heterotypic sprouting. Homotypic sprouting has the advantage of restoring both morphological and functional connections with relative ease. A model of homotypic sprouting using the rat raphe-hippocampal (RH) system has demonstrated structure, biochemical, and functional restoration of 5,7-dihydroxytryptamine (5,7-DHT) lesions in this system.;In the present work the 5-HT neurons which project to the dorsal hippocampus (DHipp) via the cingulem bundle (CB) and fimbria fornix (FF) are found to consist of two homologous groups in the median raphe nucleus (MRN). The termination of which have been studied. These fibers terminate in a coherent pattern, and densely innervate the fasciola cineria. These data provide an anatomical contribution to the RH model of homotypic sprouting.;Three days after 5,7-DHT lesions in the CB, a decrease was observed in the number of 5-HT neurons innervating DHipp (by HRP tracing) and in the fiber density of their projections in the DHipp (by immunocytochemistry). This decrement is not completely reversed until 21-42 days post-lesion. The restitution is a result of proliferation of undamaged 5-HT fibers from the FF. This is an example of homotypic collateral sprouting.;This homotypic compensatory growth in the DHipp is suppressed by adrenalectomy (ADX), The number of RH neurons remained low 21 days post-CB-lesion in these ADX animals (64% lower than sham). However, the suppression is reversed by subcutaneuous implantation of corticosterone pellets.;5,7-DHT lesion in the CB and FF removed most of the MRN innervation to the DHipp. No regeneration from the MRN occurred as late as 42 days post-lesion. However, collateral sprouting from DRN neurons, which normally innervate the ventral hippocampus, is observed innervating the DHipp.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biomedical Sciences
