Severity: Warning
Message: file_get_contents(https://...@pubfacts.com&api_key=b8daa3ad693db53b1410957c26c9a51b4908&a=1): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 176
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 176
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 250
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3122
Function: getPubMedXML
File: /var/www/html/application/controllers/Detail.php
Line: 575
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 489
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
Neuromodulatory facilitation of long-term synaptic plasticity is important in learning, memory, and experience-dependent cortical plasticity. Although muscarinic-induced long-term depression (mLTD) in the visual cortex is well known, its cellular mechanisms are not fully understood yet. Since endocannabinoid signaling mediates presynaptic expression of LTD in various brain areas including the primary visual cortex of rats, we investigated the involvement of endocannabinoids in the induction of mLTD in different dendritic compartments of layer 2/3 pyramidal neurons. With an unloading experiment of FM1-43 as an indicator of synaptic vesicle recycling, we confirmed that layer 1 and layer 4 stimulations mainly activated distal apical (in layer 1) and perisomatic (in layer 2/3) dendritic compartments, respectively. Bath application of muscarine (10 min) induced LTD in synaptic inputs activated by stimulation of layers 1 (L1-mLTD) and 4 (L2/3-mLTD). Both mLTDs were blocked by intracellular Ca chelator BAPTA and bath application of NMDA receptor antagonist d-AP5. However, only L2/3-mLTD exhibited an increase in paired-pulse ratio. In addition, only L2/3-mLTD was blocked by treatment with CB receptor antagonist AM251. Both mLTDs were blocked by intracellular NMDA receptor antagonist MK801, but not by glia-specific metabolic inhibitor fluoroacetate, implying that neither presynaptic NMDA receptors nor astrocytes are involved in mLTD. These results suggest that L2/3-mLTD is expressed presynaptically via retrograde endocannabinoid signaling while L1-mLTD is endocannabinoid independent in layer 2/3 pyramidal neurons of the visual cortex. Therefore, layer-specific involvement of endocannabinoids in the induction of mLTD might play an important role in cortical development and information processing in the neocortex.
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Source |
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http://dx.doi.org/10.1016/j.brainres.2019.02.007 | DOI Listing |
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