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Selective Requirement for Maintenance of Synaptic Contacts onto Motoneurons by Target-Derived trkB Receptors.

Zhu X, Ward PJ, English AW - Neural Plast. (2016)

Bottom Line: Selective knockout of the trkB gene resulted in a marked reduction in contacts made by VGLUT2- and GAD67-immunoreactive structures in both sexes and a significant reduction in contacts containing only glycine in male mice.No reduction was found for glycinergic contacts in female mice or for VGLUT1 immunoreactive contacts in either sex.Signaling through postsynaptic trkB receptors is considered to be an essential part of a cellular mechanism for maintaining the contacts of some, but not all, synaptic contacts onto motoneurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.

ABSTRACT
Synaptic contacts onto motoneurons were studied in mice in which the gene for the trkB neurotrophin receptor was knocked out selectively in a subset of spinal motoneurons. The extent of contacts by structures immunoreactive for either of two different vesicular glutamate transporters (VGLUT1 and VGLUT2), the vesicular GABA transporter, or glutamic acid decarboxylase 67 (GAD67) with the somata of motoneurons, was studied in wild type and trkB knockout cells in tamoxifen treated male and female SLICK-trkB(-/-) mice. Selective knockout of the trkB gene resulted in a marked reduction in contacts made by VGLUT2- and GAD67-immunoreactive structures in both sexes and a significant reduction in contacts containing only glycine in male mice. No reduction was found for glycinergic contacts in female mice or for VGLUT1 immunoreactive contacts in either sex. Signaling through postsynaptic trkB receptors is considered to be an essential part of a cellular mechanism for maintaining the contacts of some, but not all, synaptic contacts onto motoneurons.

No MeSH data available.


Related in: MedlinePlus

Cumulative frequency plots of percent coverage by structures immunoreactive to different synapse-associated proteins onto the soma and proximal-most dendrites of labeled motoneurons in tamoxifen treated and untreated SLICK::trkBf/f male (left) and tamoxifen treated female (right) mice. WT (black symbols) refers to wildtype motoneurons in tamoxifen treated mice, without YFP, that still retain trkB receptors. KO (white symbols) refers to knockout motoneurons labeled with YFP that do not have trkB receptors. Control (dashed line) refers to data from male SLICK::trkBf/f mice not treated with tamoxifen. Data from all the mice in each group were pooled. (a) VGLUT1. (b) VGLUT2. (c) GAD67. (d) VGAT.
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fig3: Cumulative frequency plots of percent coverage by structures immunoreactive to different synapse-associated proteins onto the soma and proximal-most dendrites of labeled motoneurons in tamoxifen treated and untreated SLICK::trkBf/f male (left) and tamoxifen treated female (right) mice. WT (black symbols) refers to wildtype motoneurons in tamoxifen treated mice, without YFP, that still retain trkB receptors. KO (white symbols) refers to knockout motoneurons labeled with YFP that do not have trkB receptors. Control (dashed line) refers to data from male SLICK::trkBf/f mice not treated with tamoxifen. Data from all the mice in each group were pooled. (a) VGLUT1. (b) VGLUT2. (c) GAD67. (d) VGAT.

Mentions: We pooled data from all of the mice in each group and tested whether the frequency distributions of coverages by VGLUT1 immunoreactive contacts were significantly different between pairs of groups using the nonparametric Mann-Whitney U test. These distributions for VGLUT1+ contacts are shown in Figure 3(a). In male mice, no significant differences were found between the distributions of coverages in WT and KO cells, or between either of these and cells from control mice (Figure 3(a), left). In females, a slight but significant (U test, p < 0.04) shift to the left in the distributions of synaptic coverages onto KO cells was found relative to that of WT cells (Figure 3(a), right). This difference is due to slightly larger synaptic coverage in the WT cells of females (U test, WT male versus female, p < 0.05), as the distributions of coverages in the KO cells of both sexes were not significantly different (U test, n.s.).


Selective Requirement for Maintenance of Synaptic Contacts onto Motoneurons by Target-Derived trkB Receptors.

Zhu X, Ward PJ, English AW - Neural Plast. (2016)

Cumulative frequency plots of percent coverage by structures immunoreactive to different synapse-associated proteins onto the soma and proximal-most dendrites of labeled motoneurons in tamoxifen treated and untreated SLICK::trkBf/f male (left) and tamoxifen treated female (right) mice. WT (black symbols) refers to wildtype motoneurons in tamoxifen treated mice, without YFP, that still retain trkB receptors. KO (white symbols) refers to knockout motoneurons labeled with YFP that do not have trkB receptors. Control (dashed line) refers to data from male SLICK::trkBf/f mice not treated with tamoxifen. Data from all the mice in each group were pooled. (a) VGLUT1. (b) VGLUT2. (c) GAD67. (d) VGAT.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig3: Cumulative frequency plots of percent coverage by structures immunoreactive to different synapse-associated proteins onto the soma and proximal-most dendrites of labeled motoneurons in tamoxifen treated and untreated SLICK::trkBf/f male (left) and tamoxifen treated female (right) mice. WT (black symbols) refers to wildtype motoneurons in tamoxifen treated mice, without YFP, that still retain trkB receptors. KO (white symbols) refers to knockout motoneurons labeled with YFP that do not have trkB receptors. Control (dashed line) refers to data from male SLICK::trkBf/f mice not treated with tamoxifen. Data from all the mice in each group were pooled. (a) VGLUT1. (b) VGLUT2. (c) GAD67. (d) VGAT.
Mentions: We pooled data from all of the mice in each group and tested whether the frequency distributions of coverages by VGLUT1 immunoreactive contacts were significantly different between pairs of groups using the nonparametric Mann-Whitney U test. These distributions for VGLUT1+ contacts are shown in Figure 3(a). In male mice, no significant differences were found between the distributions of coverages in WT and KO cells, or between either of these and cells from control mice (Figure 3(a), left). In females, a slight but significant (U test, p < 0.04) shift to the left in the distributions of synaptic coverages onto KO cells was found relative to that of WT cells (Figure 3(a), right). This difference is due to slightly larger synaptic coverage in the WT cells of females (U test, WT male versus female, p < 0.05), as the distributions of coverages in the KO cells of both sexes were not significantly different (U test, n.s.).

Bottom Line: Selective knockout of the trkB gene resulted in a marked reduction in contacts made by VGLUT2- and GAD67-immunoreactive structures in both sexes and a significant reduction in contacts containing only glycine in male mice.No reduction was found for glycinergic contacts in female mice or for VGLUT1 immunoreactive contacts in either sex.Signaling through postsynaptic trkB receptors is considered to be an essential part of a cellular mechanism for maintaining the contacts of some, but not all, synaptic contacts onto motoneurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.

ABSTRACT
Synaptic contacts onto motoneurons were studied in mice in which the gene for the trkB neurotrophin receptor was knocked out selectively in a subset of spinal motoneurons. The extent of contacts by structures immunoreactive for either of two different vesicular glutamate transporters (VGLUT1 and VGLUT2), the vesicular GABA transporter, or glutamic acid decarboxylase 67 (GAD67) with the somata of motoneurons, was studied in wild type and trkB knockout cells in tamoxifen treated male and female SLICK-trkB(-/-) mice. Selective knockout of the trkB gene resulted in a marked reduction in contacts made by VGLUT2- and GAD67-immunoreactive structures in both sexes and a significant reduction in contacts containing only glycine in male mice. No reduction was found for glycinergic contacts in female mice or for VGLUT1 immunoreactive contacts in either sex. Signaling through postsynaptic trkB receptors is considered to be an essential part of a cellular mechanism for maintaining the contacts of some, but not all, synaptic contacts onto motoneurons.

No MeSH data available.


Related in: MedlinePlus