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Ultrastructural localization of cannabinoid CB1 and mGluR5 receptors in the prefrontal cortex and amygdala.
- Source :
-
The Journal of comparative neurology [J Comp Neurol] 2019 Nov 01; Vol. 527 (16), pp. 2730-2741. Date of Electronic Publication: 2019 May 10. - Publication Year :
- 2019
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Abstract
- Stimulation of the postsynaptic metabotropic glutamate receptor mGluR5 triggers retrograde signaling of endocannabinoids that activate presynaptic cannabinoid CB1 receptors on juxtaposing axon terminals. To better understand the synaptic structure that supports mGluR5 mediation of CB1 activation in the prefrontal cortex (PFC) and basolateral amygdala (BLA), we examined electron microscopic dual immunolabeling of these receptors in the prelimbic PFC (prPFC) and BLA of adult male rats. CB1 immunoreactivity was detected in axon terminals that were typically large, complex, and contained dense-core and clear synaptic vesicles. Of terminals forming discernible synaptic specializations, 95% were symmetric inhibitory-type in the prPFC and 90% were inhibitory in the BLA. CB1-immunoreactive terminals frequently contacted dendrites containing mGluR5 adjacent to unlabeled terminals forming excitatory-type synapses. Because most CB1-containing terminals form inhibitory-type synapses, the unlabeled axon terminals forming asymmetric synapses are the likely source of the mGluR5 ligand glutamate. In the prPFC, serial section analysis revealed that GABAergic CB1-containing axon terminals targeted dendrites adjacent to glutamatergic axon terminals, often near dendritic bifurcations. These observations provide ultrastructural evidence that cortical CB1 receptors are strategically positioned for integration of synaptic signaling in response to stimulation of postsynaptic mGluR5 receptors and facilitation of heterosynaptic communication between multiple neurons.<br /> (© 2019 Wiley Periodicals, Inc.)
- Subjects :
- Animals
Axons metabolism
Axons ultrastructure
Dendrites metabolism
Dendrites ultrastructure
Immunohistochemistry
Male
Microscopy, Electron
Rats, Sprague-Dawley
Synapses metabolism
Synapses ultrastructure
Amygdala metabolism
Amygdala ultrastructure
Prefrontal Cortex metabolism
Prefrontal Cortex ultrastructure
Receptor, Cannabinoid, CB1 metabolism
Receptor, Metabotropic Glutamate 5 metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1096-9861
- Volume :
- 527
- Issue :
- 16
- Database :
- MEDLINE
- Journal :
- The Journal of comparative neurology
- Publication Type :
- Academic Journal
- Accession number :
- 31008528
- Full Text :
- https://doi.org/10.1002/cne.24704