Molecular and functional diversity of basal forebrain neurons during aging /
The medial septum and nucleus of the diagonal band (MS/nDB) contain cholinergic and GABAergic neuronal populations that have been identified based on immunohistochemical staining and/or electrophysiological properties. We explored the molecular diversity of MS/nDB neurons using single-cell reverse...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2002.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=726464411&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The medial septum and nucleus of the diagonal band (MS/nDB) contain cholinergic and GABAergic neuronal populations that have been identified based on immunohistochemical staining and/or electrophysiological properties. We explored the molecular diversity of MS/nDB neurons using single-cell reverse transcription/polymerase chain reaction (scRT-PCR) to assess gene expression profiles during aging in individual neurons acutely isolated from young (1.5-4 mo) and aged (22-27 mo) Fischer 344 rats. Neuronal gene expression profiles were characterized by detection of mRNAs for choline acetyltransferase (ChAT, cholinergic) and glutamate decarboxylase (GAD67, GABAergic), as well as mRNAs for calcium binding proteins (CaBPs) calbindin-D28k, calretinin and parvalbumin. Four major neuronal populations were identified: ChAT-positive (ChAT+) cells, GAD-positive (GAD+) cells, ChAT+/GAD+ cells, and ChAT negative/GAD negative (ChAT-/GAD-) cells. With age, the percentage of cells expressing both ChAT and GAD67 mRNA was reduced while the percentage of ChAT-/GAD- cells increased. Of the CaBPs, calretinin expression was observed most frequently in this study, and its detection decreased with age. Observations concerning the CaBPs were confirmed using in situ hybridization. The diversity of MS/nDB cells during aging was further verified using semi-quantitative mRNA expression levels and functional analysis of voltage-dependent calcium currents. The amount of ChAT mRNA in single cells increased during aging and this was accompanied by an increase in the current density of low voltage-activated (LVA) calcium currents. These age-related changes were specific for ChAT+ neurons but not observed in another cholinergic phenotype, ChAT+/GAD+ cells. ChAT+ and ChAT+/GAD+ cells were the only phenotypes to show typical LVA currents, whereas, GAD+ and ChAT-/GAD- cells displayed a fast inactivating current. Also relative ChAT mRNA levels in ChAT+ and ChAT+/GAD+ cells were very similar, however GAD mRNA levels within ChAT+/GAD+ cells were very low relative to GAD+ cells. All these results suggest a shift in the mRNA expression profiles of MS/nDB neuronal populations during aging and exemplify the molecular diversity of cholinergic and GABAergic cells. |
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| Item Description: | Vita. "Major Subject: Medical Sciences". |
| Physical Description: | xii, 180 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 154-179). |