NSM
From NeuronBankWiki
NSM is a neurosecretory-motor neuron found in the pharynx of Caenorhabditis elegans.
Contents |
General Information
NSM is a neurosecretory-motor neuron located in the pharynx of C. elegans. The neurons are bipolar and they exist in pairs (NSML/NSMR) and localize on the right and left sides of the animal in a bilaterally symmetric manner. These cells may have both neurosecretory and motor function and may signal the presence of food to the rest of the animal’s body. NSM contains serotonin and uses it as a neurotransmitter. Cell’s release of serotonin contributes to such behaviors including increased rate of pharyngeal pumping, decreased locomotion, and more egg-laying. The cell is stained most strongly and reliably with anti-serotonin. NSMs receive extensive synapses from I2 (interneuron at the most anterior end of the subventral nerve cords).
Anatomy
Soma of NSM is located in the pharyngeal subventral nerve cords just anterior to the nerve ring. The cell extends one major process which bifurcates near the cell body. One branch of the process crosses to the opposite side of the body, turns dorsally and continues its pathway posteriorly within the dorsal nerve cord of the isthmus (Media:isthmus.bmp) . The other branch runs posteriorly within the subventral nerve cord of the isthmus. Within the isthmus, these processes periodically swell to form vesicles. Major processes of NSMs run very close to pseudocoelom.
Along with these major processes NSM's also have small, synapse-free processes with free endings just under the cuticle of the pharyngeal lumen at the boundary between the corpus and isthmus (where bacteria accumulate). These endings are attached to the adjacent muscle cells by desmosomes and are thought to act as stretch receptors.
Molecular profile
Neurotransmitter: Serotonin works as a direct and indirect excitatory for the pharynx of C. elegans. Glutamate is a direct inhibitory.
Function
NSM functions to signal the presence of food to the rest of animal’s body using a neurotransmitter, serotonin. Release of serotonin induces physical responses such as faster pharyngeal pumping, slowing of locomotion, and more egg-laying. However, there have been some researches suggesting that NSM only has subtle effects on pharyngeal pumping action and may be redundant for this function.
Synaptic Connections
NSMs make synapses to the pharyngeal basement membrane and muscle cells.
Synaptic Inputs
NSMs receive extensive synapses from I2 (pharyngeal interneuron at the most anterior end of the subventral nerve cords).
References
1. Avery, L. Bargmann, C.I. and Horvitz, H.R. 1993. The Caenorhabditis elegans unc-31 gene affects multiple nervous system-controlled functions . Genetics 134: 454-464.
2. WormAtlas, Altun, Z.F., Herndon, L.A., Crocker, C., Lints, R. and Hall, D.H. (ed.s) 2002-2009. http://www.wormatlas.org
