| Title | Mrgprd-expressing polymodal nociceptive neurons innervate most known classes of substantia gelatinosa neurons. | | Author(s) | Wang H, Zylka MJ | | Institution | Department of Cell and Molecular Physiology, University of North Carolina Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA. | | Source | J Neurosci 2009 Oct 21; 29(42):13202-9. | | MeSH | Animals
Biophysics
Calcitonin Gene-Related Peptide
Cells, Cultured
Electric Stimulation
Excitatory Postsynaptic Potentials
Ganglia, Spinal
Green Fluorescent Proteins
Lectins
Membrane Potentials
Mice
Mice, Inbred C57BL
Mice, Transgenic
Nerve Net
Nociceptors
Patch-Clamp Techniques
Photic Stimulation
Receptors, G-Protein-Coupled
Rhodopsin
Sensory Receptor Cells
Substantia Gelatinosa
| | Abstract | The Mas-related G-protein-coupled receptor D (Mrgprd) marks a distinct subset of sensory neurons that transmit polymodal nociceptive information from the skin epidermis to the substantia gelatinosa (SG, lamina II) of the spinal cord. Moreover, Mrgprd-expressing (Mrgprd(+)) neurons are required for the full expression of mechanical but not thermal nociception. While such anatomical and functional specificity suggests Mrgprd(+) neurons might synapse with specific postsynaptic targets in the SG, precisely how Mrgprd(+) neurons interface with spinal circuits is currently unknown. To study circuit connectivity, we genetically targeted the light-activated ion channel Channelrhodopsin-2-Venus (ChR2-Venus) to the Mrgprd locus. In these knock-in mice, ChR2-Venus was localized to nonpeptidergic Mrgprd(+) neurons and axons, while peptidergic CGRP(+) neurons were not significantly labeled. Dissociated Mrgprd(+) DRG neurons from mice expressing one or two copies of ChR2-Venus could be activated in vitro as evidenced by light-evoked currents and action potentials. In addition, illumination of Mrgprd-ChR2-Venus(+) axon terminals in spinal cord slices evoked EPSCs in half of all SG neurons. Within this subset, Mrgprd(+) neurons were monosynaptically connected to most known classes of SG neurons, including radial, tonic central, transient central, vertical, and antenna cells. This cellular diversity ruled out the possibility that Mrgprd(+) neurons innervate a dedicated class of SG neuron. Our findings set broad constraints on the types of spinal neurons that process afferent input from Mrgprd(+) polymodal nociceptors. | | Language | eng | | Pub Type(s) | In Vitro
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
| | PubMed ID | 19846708 |
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