PVDL, PVDR

Type: Sensory neuron (polymodal nociceptive for mechanosensation and thermosensation)
In MoW: PVD
Male Wiring Project: PVDL, PVDR
In Wormbase: PVD, PVDL, PVDR
Lineage: V5L.paapa, V5R.paapa
Location: Tail; lumbar ganglion
Description: Postembryonically born (see V lineage). PVDL/R have extensive branching pattern in adult animals. In early larval stages 3 major processes are discerned; one anteriorly directed, one posteriorly directed and one ventrally directed. The anteriorly- and posteriorly-directed processes show short extensions and branches along their length at this stage. As the animal ages, starting from L2, this branching pattern is elaborated extensively by growth and retraction, finally forming well-ordered, repeating menorah-like units at L4 (Oren-Suissa et al., 2010). The quaternary branches of these menorahs are about 30-60 nm in diameter. Unlike touch receptor neuron (TRN) processes, these branches have no prominent cytoskeletons inside and are not

linked to the body wall through a specialized mantle of extracellular matrix outside (See e.g., NeuroFig 9D-J in Nervous System)(Hall & Treinin, 2011.) In the final form, the "menorahs" are non-overlapping and regularly spaced in an array. Topologically PVD neuron processes cover most of the body except neck and head (Hall & Treinin, 2011; Oren-Suissa et al., 2010; Smith et al., 2010; Hall & Altun, 2008). FLP neurons, which have similar dendritic arborization structure cover the neck and head instead (Hall & Altun, 2008).
Neurotransmitter/ Neuropeptide:
- Glutamate
- NLP-11; neuropeptide-like protein
(Nathoo et al., 2001; Lee et al., 1999)
Innexin expression:
- INX-12
- UNC-7
- UNC-9
(Altun et al., 2009)
Receptor expression:
- DEG-3; alpha subunit of a nicotinic acetylcholine receptor
- DEGT-1; mechanically gated ion channel subunit; amiloride-sensitive Na+ channel (ASC) protein (DEG/ENaC subunit). - part of a mechanosensory transduction channel. Colocalizes with MEC-10 on the primary and tertiary branches of PVD
- DES-2; alpha subunit of a nicotinic acetylcholine receptor
- GLR-4; glutamate receptor subunit
- MEC-6; part of the degenerin/epithelial Na+channel complex - interacts physically with the MEC-4 degenerin ion channel
- MEC-9; provides an extracellular attachment point for the mechanosensory channels in touch cells
- MEC-10; mechanically gated ion channel subunit; amiloride-sensitive Na+ channel (ASC) protein (DEG/ENaC subunit). - part of a mechanosensory transduction channel. Colocalizes with DEGT-1 on the primary and tertiary branches of PVD
- OSM-9; transient receptor potential (TRPV) ion channel protein
- SER-2; splice variant of the tyramine receptor .
- TRPA-1; transient receptor potential ion channel (TRPA, TRPM and TRPV ion channel families are considered "thermoTRPs" that sense temperature"). Activation of TRPA-1 in cold-sensitive neurons and the intestine is required for cold-induced longevity via DAF-16.
(Wormbase; Xiao et al., 2013; Altun, 2011; Kindt et al., 2007; Tsalik et al., 2003; Rex and Komuniecki, 2002; Brockie et al., 2001; Chelur et al., 2002; Colbert et al., 1997; Treinin et al., 1998; Treinin and Chalfie, 1995; Huang and Chalfie, 1994; Du et al., 1996)
Function:
- PVD neurons are multidendritic nociceptors that respond to harsh touch (as stretch-sensing mechanosensor) and cold temperatures (cold hyperalgesia). Animals in which PVD neurons are laser-ablated fail to respond to harsh touch to the central region of the body but can respond to harsh touch to the head and tail tap. The harsh touch modality specifically requires the DEG/ENaC proteins MEC-10 and DEGT-1, while responses to cold require the TRPA-1 channel and are MEC-10- and DEGT-1-independent . Hence, polymodal nociception in PVD neurons involves parallel sensory transduction channels (Chatzigeorgiou et al., 2010; Way and Chalfie, 1989). It has been suggested that application of a harsh mechanical stimulus stretches the tertiary processes by displacing the quarternary branches, which do not contain any mechanosensory ion channels themselves. The pulling force transmitted to the tertiary processes leads to local DEG/ENaC opening in primary and tertiary neurites instead (See image below; Hall & Treinin, 2011). PVD is possibly not involved in the circuit that mediates suppression of pharyngeal pumping in response to a touch stimulus in adults (Keane and Avery, 2003).
Click image for closeup view Click pictures for higher resolution images


Last revision: March 3, 2015
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