Submucosal enteric neurons of the cavine distal colon are sensitive to hypoosmolar stimuli

Abstract

Neurons of the enteric submucous plexus are challenged by osmolar fluctuations during digestion and absorption of nutrients. r Central neurons are very sensitive to changes in osmolality but knowledge on that issue related to enteric neurons is sparse. r The present study focuses on investigation of osmosensitivity of submucosal neurons including potential molecular mediating mechanisms. r Results show that submucosal neurons respond to hypoosmolar stimuli with increased activity which is partially mediated by the transient receptor potential vanilloid 4 channel. r We provided important information on osmosensitive properties of enteric neurons. These data are fundamental to better explain the nerve-mediated control of the gastrointestinal functions during physiological and pathophysiological (diarrhoea) conditions.

TRPV3 and TRPV4 as candidate proteins for intestinal ammonium absorption

“…11 A number of studies suggest an important role for TRPV4 in the regulation of gastric motility and emptying. 70 In the colon, the channel is thought to play diverse roles in osmosensation 6,71 and regulation of barrier function, 56 with possible implications for diseases such as ulcerative colitis. 72 In the current study, the largest amount of mRNA for TRPV4 was found in the mucosa of the stomach (cardia and fundus; Figure 1D).…”

Sensing osmolarity: a new player on the field

“…The study by Kollmann et al . (2020) additionally provides the first hints for the signal mechanism involved in osmosensation by enteric neurons as their pharmacological approaches – supported by the proof of expression on the mRNA level via qPCR – clearly indicate that TRPV4 plays an essential role in the reception mechanism. TRPV4 is a polymodal ionotropic receptor (Kumar et al .…”

“…In this issue of The Journal of Physiology , Kollmann et al . (2020) describe the response of submucosal neurons to hypoosmolar stimuli. Depending on the amplitude of the decrease in osmolarity, up to about one tenth of these neurons reacted with an action potential discharge concomitant with an increase in the cytosolic Ca 2+ concentration when exposed to a locally applied puff of a hypotonic solution.…”

“…The data from Kollmann et al . (2020) now reveal the existence of a new, previously unknown player on the field of osmosensitivity, i.e the submucosal plexus. Effector neurons of this part of the enteric nervous system are known to regulate, for example, ion transport across the intestinal epithelium, epithelial permeability or perfusion of the gut wall.…”

“…As should be the case for a study opening new perspectives in physiology, the present paper by Kollmann et al . (2020) evokes a plethora of questions to be addressed in future experiments by researchers in the relevant fields. A fundamental general biophysical question is how TRPV4, like many other members of this superfamily of cation channels, is activated by the different physical or chemical stimuli modifying its open probability.…”