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Manganese-Enhanced MRI Reflects Both Activity-Independent and Activity-Dependent Uptake within the Rat Habenulomesencephalic Pathway
Manganese-enhanced magnetic resonance imaging (MEMRI) is a powerful technique for assessing the functional connectivity of neurons within the central nervous system. Despite the widely held proposition that MEMRI signal is dependent on neuronal activity, few studies have directly tested this implici...
Autores principales: | , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443977/ https://www.ncbi.nlm.nih.gov/pubmed/26009889 http://dx.doi.org/10.1371/journal.pone.0127773 |
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author | Wang, Leiming Lu, Hanbing Brown, P. Leon Rea, William Vaupel, Bruce Yang, Yihong Stein, Elliot Shepard, Paul D. |
author_facet | Wang, Leiming Lu, Hanbing Brown, P. Leon Rea, William Vaupel, Bruce Yang, Yihong Stein, Elliot Shepard, Paul D. |
author_sort | Wang, Leiming |
collection | PubMed |
description | Manganese-enhanced magnetic resonance imaging (MEMRI) is a powerful technique for assessing the functional connectivity of neurons within the central nervous system. Despite the widely held proposition that MEMRI signal is dependent on neuronal activity, few studies have directly tested this implicit hypothesis. In the present series of experiments, MnCl(2) was injected into the habenula of urethane-anesthetized rats alone or in combination with drugs known to alter neuronal activity by modulating specific voltage- and/or ligand-gated ion channels. Continuous quantitative T1 mapping was used to measure Mn(2+) accumulation in the interpeduncular nucleus, a midline structure in which efferents from the medial habenula terminate. Microinjection of MnCl(2) into the habenular complex using a protocol that maintained spontaneous neuronal activity resulted in a time-dependent increase in MEMRI signal intensity in the interpeduncular nucleus consistent with fast axonal transport of Mn(2+) between these structures. Co-injection of the excitatory amino-acid agonist AMPA, increased the Mn(2+)-enhanced signal intensity within the interpeduncular nucleus. AMPA-induced increases in MEMRI signal were attenuated by co-injection of either the sodium channel blocker, TTX, or broad-spectrum Ca(2+) channel blocker, Ni(2+), and were occluded in the presence of both channel blockers. However, neither Ni(2+) nor TTX, alone or in combination, attenuated the increase in signal intensity following injection of Mn(2+) into the habenula. These results support the premise that changes in neuronal excitability are reflected by corresponding changes in MEMRI signal intensity. However, they also suggest that basal rates of Mn(2+) uptake by neurons in the medial habenula may also occur via activity-independent mechanisms. |
format | Online Article Text |
id | pubmed-4443977 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-44439772015-06-16 Manganese-Enhanced MRI Reflects Both Activity-Independent and Activity-Dependent Uptake within the Rat Habenulomesencephalic Pathway Wang, Leiming Lu, Hanbing Brown, P. Leon Rea, William Vaupel, Bruce Yang, Yihong Stein, Elliot Shepard, Paul D. PLoS One Research Article Manganese-enhanced magnetic resonance imaging (MEMRI) is a powerful technique for assessing the functional connectivity of neurons within the central nervous system. Despite the widely held proposition that MEMRI signal is dependent on neuronal activity, few studies have directly tested this implicit hypothesis. In the present series of experiments, MnCl(2) was injected into the habenula of urethane-anesthetized rats alone or in combination with drugs known to alter neuronal activity by modulating specific voltage- and/or ligand-gated ion channels. Continuous quantitative T1 mapping was used to measure Mn(2+) accumulation in the interpeduncular nucleus, a midline structure in which efferents from the medial habenula terminate. Microinjection of MnCl(2) into the habenular complex using a protocol that maintained spontaneous neuronal activity resulted in a time-dependent increase in MEMRI signal intensity in the interpeduncular nucleus consistent with fast axonal transport of Mn(2+) between these structures. Co-injection of the excitatory amino-acid agonist AMPA, increased the Mn(2+)-enhanced signal intensity within the interpeduncular nucleus. AMPA-induced increases in MEMRI signal were attenuated by co-injection of either the sodium channel blocker, TTX, or broad-spectrum Ca(2+) channel blocker, Ni(2+), and were occluded in the presence of both channel blockers. However, neither Ni(2+) nor TTX, alone or in combination, attenuated the increase in signal intensity following injection of Mn(2+) into the habenula. These results support the premise that changes in neuronal excitability are reflected by corresponding changes in MEMRI signal intensity. However, they also suggest that basal rates of Mn(2+) uptake by neurons in the medial habenula may also occur via activity-independent mechanisms. Public Library of Science 2015-05-26 /pmc/articles/PMC4443977/ /pubmed/26009889 http://dx.doi.org/10.1371/journal.pone.0127773 Text en https://creativecommons.org/publicdomain/zero/1.0/ This is an open-access article distributed under the terms of the Creative Commons Public Domain declaration, which stipulates that, once placed in the public domain, this work may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. |
spellingShingle | Research Article Wang, Leiming Lu, Hanbing Brown, P. Leon Rea, William Vaupel, Bruce Yang, Yihong Stein, Elliot Shepard, Paul D. Manganese-Enhanced MRI Reflects Both Activity-Independent and Activity-Dependent Uptake within the Rat Habenulomesencephalic Pathway |
title | Manganese-Enhanced MRI Reflects Both Activity-Independent and Activity-Dependent Uptake within the Rat Habenulomesencephalic Pathway |
title_full | Manganese-Enhanced MRI Reflects Both Activity-Independent and Activity-Dependent Uptake within the Rat Habenulomesencephalic Pathway |
title_fullStr | Manganese-Enhanced MRI Reflects Both Activity-Independent and Activity-Dependent Uptake within the Rat Habenulomesencephalic Pathway |
title_full_unstemmed | Manganese-Enhanced MRI Reflects Both Activity-Independent and Activity-Dependent Uptake within the Rat Habenulomesencephalic Pathway |
title_short | Manganese-Enhanced MRI Reflects Both Activity-Independent and Activity-Dependent Uptake within the Rat Habenulomesencephalic Pathway |
title_sort | manganese-enhanced mri reflects both activity-independent and activity-dependent uptake within the rat habenulomesencephalic pathway |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443977/ https://www.ncbi.nlm.nih.gov/pubmed/26009889 http://dx.doi.org/10.1371/journal.pone.0127773 |
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