Calcium channels in enteric neurons

American Journal of Physiology-Gastrointestinal and Liver Physi

Jiang

Srinivasan

et al. 2013

S, Mittal RK. Morphological, immunocytochemical, and functional characterization of esophageal enteric neurons in primary culture. Am J Physiol Gastrointest Liver Physiol 305: G129-G138, 2013. First published May 9, 2013 doi:10.1152/ajpgi.00040.2013The enteric nervous system of the esophagus plays an important role in its sensory and motor functions. Although the esophagus contains enteric neurons, they have never been isolated and characterized in primary culture. We isolated and cultured enteric neurons of the rat esophagus and determined their morphological appearance, chemical coding for neurotransmitters, and functional characteristics. After primary culture for 2 wk, dendrites and axons appeared in the enteric neurons, which usually have one axon and several dendrites. Although the size of neuronal bodies varied from Dogiel type I to type II, their average size was 39 Ϯ 1.8 m in length and 23 Ϯ 1.4 m in width. Immmunocytochemical studies revealed that over 95% of these cells were positively stained for two general neuronal markers, PGP 9.5 or Milli-Mark Fluoro. Chemical coding showed that the neurons were positively stained for choline acetyltransferease (53 Ϯ 6%) or nNOS (66 Ϯ 13%). In functional studies, membrane depolarization and stimulation of several G protein-coupled receptors (GPCRs) induced Ca 2ϩ signaling in the esophageal enteric neurons. The GPCR stimulation was found to induce both intracellular Ca 2ϩ release and extracellular Ca 2ϩ entry. The functional expressions of Ca 2ϩ channels (voltage-gated Ca 2ϩ channels and store-operated channels) and Ca 2ϩ pump (sarcoplasmic reticulum Ca 2ϩ -ATPase) were also demonstrated on these neurons. We have grown, for the first time, esophageal enteric neurons in primary culture, and these contain excitatory and inhibitory neurotransmitters. The functional integrity of GPCRs, Ca 2ϩ channels, and Ca 2ϩ pump in these neurons makes them a useful cell model for further studies. choline acetyltransferease; nitric oxide synthase; cytoplasmic free calcium ion; G protein-coupled receptors; calcium ion channels; calcium ion pump THE ENTERIC NERVOUS SYSTEM (ENS) plays an essential role in the regulation of gastrointestinal motility (4,19,35). Enteric neurons have many different functions in the ENS, and broadly they are divided into three major types, 1) sensory neurons (intrinsic primary afferent neurons), 2) interneurons, and 3) motor neurons (4, 19). Motor neurons are further divided into excitatory and inhibitory types based on their regulatory functions on the gastrointestinal motility (4, 18). Excitatory motor neurons contain excitatory neurotransmitters, such as acetylcholine (ACh), substance P, and N-methyl-D-aspartate (NMDA) (19). On the other hand, inhibitory motor neurons predominantly contain inhibitory neurotransmitters, such as NO, ATP, and VIP (19,35).Enteric neurons located in the wall of esophagus play an important role in its sensory and motor functions (18,19,42). The esophageal enteric motor neurons have their cell bodies in the myenteric ganglia, ...

Section: Discussionmentioning

confidence: 99%

“…Figure 5C shows histograms of the summary data of neuronal responses to high K ϩ in the absence and presence of nifedipine. These data suggest the functional expression of VGCC on esophageal neurons, although the subtypes of VGCC need further identification (36).…”

Section: Ca 2ϩ -Permeable Channels and Ca 2ϩ Pumpsmentioning

confidence: 99%

Morphological, immunocytochemical, and functional characterization of esophageal enteric neurons in primary culture

American Journal of Physiology-Gastrointestinal and Liver Physi

Jiang

Srinivasan

et al. 2013

“…Similar to many other types of mammalian cells, different Ca 2ϩ influx pathways, voltage-gated Ca 2ϩ channels (VGCCs) (3,40), receptor-operated Ca 2ϩ channels, and storeoperated Ca 2ϩ channels are observed in various types of neurons. A Ca 2ϩ influx pathway, Ca 2ϩ -permeable channels activated by mechanical stretch, so-called stretch-activated cation channels (SACs), has been found in various cell types, including neurons (32,35).…”

mentioning

confidence: 99%

Inhibitory motor neurons of the esophageal myenteric plexus are mechanosensitive

Jiang

American Journal of Physiology-Cell Physiology

et al. 2015

Mittal RK. Inhibitory motor neurons of the esophageal myenteric plexus are mechanosensitive. Am J Physiol Cell Physiol 308: C405-C413, 2015. First published December 24, 2014; doi:10.1152/ajpcell.00159.2014.-Mechanosensitivity of enteric neurons has been reported in the small intestine and colon, but not in the esophagus. Our earlier in vivo studies show that mechanical stretch of the esophagus in the axial direction induces neurally mediated relaxation of the lower esophageal sphincter, possibly through mechanosensitive motor neurons. However, this novel notion that the motor neurons are mechanosensitive has not been examined in isolated esophageal myenteric motor neurons. The goal of our present study was to examine the mechanosensitivity of esophageal motor neurons in primary culture and elucidate the underlying molecular mechanisms. Immmunocytochemical analysis revealed that Ͼ95% cells were positive for the neuronal marker protein gene product 9.5 and that 66% of these cells costained with protein gene product 9.5 and neuronal nitric oxide (NO) synthase. Hypotonic solution induced an increase in the cytoplasm volume in all cells that was independent of extracellular Ca 2ϩ . Hypotonic solution and mechanical stretch induced cytoplasmic free Ca 2ϩ signaling in ϳ65% of neurons in the presence, but not absence, of extracellular Ca 2ϩ . Neurons grown on the elastic membrane responded to mechanical stretch by an increase in neuronal size and Ca 2ϩ signaling simultaneously. Hypotonic stretch-induced cytoplasmic free Ca 2ϩ signaling was not affected by extracellular Mg 2ϩ , 5-nitro-2-(3-phenylpropylamino)benzoic acid, and nifedipine but was attenuated by 2-aminoethoxydiphenyl borate, Gd 3ϩ , and Grammostola mechanotoxin 4, blockers of the stretch-activated ion channels. In ϳ57% of the neurons, hypotonic stretch also induced Ca 2ϩ -dependent cytoplasmic NO production, which was abolished by Grammostola mechanotoxin 4. These results prove that the esophageal inhibitory motor neurons possess a mechanosensitive property and also provide novel insights into the stretch-activated ion channel-Ca 2ϩ -NO signaling pathway in these neurons. neuronal nitric oxide synthase; nitric oxide production; cytoplasmic free calcium; stretch-activated cation channels THE ENTERIC NERVOUS SYSTEM regulates gastrointestinal (GI) functions, such as digestion, absorption, secretion, motility, and sensation (1, 14, 37). The enteric nervous system contains three types of neurons: 1) sensory neurons [intrinsic primary afferent neurons (IPANs)], 2) interneurons, and 3) motor neurons (1, 14). The latter are further subdivided into excitatory and inhibitory motor neurons on the basis of their regulatory functions (1, 15): excitatory motor neurons contain neurotransmitters, such as acetylcholine, substance P, and glutamate (14), and inhibitory motor neurons contain nitric oxide (NO), ATP, and vasoactive intestinal polypeptide (14, 37).Similar to neurons in the rest of the GI tract, neurons in the wall of esophagus also play an important role in the s...

“…This is significant because once these cells invade, complex signaling mechanisms, that to date remain elusive, controls their migration, proliferation and differentiation into many different neuronal subtypes (Heanue and Pachnis, 2006). The contribution to this signaling by γ3 is not known, but this subunit is coupled to L-type Ca 2+ channel activity (MacrezLepretre et al, 1997), which has a major influence in the enteric nervous system (reviewed in Smith et al, 2003).…”

Section: B C D Ementioning

confidence: 99%

Mouse G-protein gamma3 expression in the developing CNS and neural crest cell derivatives

Kelly¹,

Saijoh²,

Finkielsztein³

et al. 2008

Int. J. Dev. Biol.