Enteric RET inhibition attenuates gastrointestinal secretion and motility via cholinergic signaling in rat colonic mucosal preparations

• Published in: Neurogastroenterology and motility 2019-04, Vol.31 (4), p.e13479-n/a
• Main Authors: Russell, John P., Mohammadi, Ehsan, Ligon, Casey, Latorre, Rocco, Johnson, Anthony C., Hoang, Bao, Krull, David, Ho, Melisa W.‐Y., Eidam, Hilary S., DeMartino, Michael P., Cheung, Mui, Oliff, Allen I., Kumar, Sanjay, Greenwood‐Van Meerveld, Beverley
• Format: Article
• Language: English
• Subjects: Acetylcholine; Acetylcholinesterase; Acetyltransferase; Animals; Carbachol; Choline; Choline O-acetyltransferase; Choline O-Acetyltransferase - metabolism; cholinergic; Cholinergic Agonists - pharmacology; Cholinergic nerves; Cholinergic Neurons - drug effects; Cholinergic Neurons - metabolism; Colon; Colon - drug effects; Colon - metabolism; Defecation - drug effects; Diarrhea; Enteric nervous system; Enteric Nervous System - drug effects; Enteric Nervous System - metabolism; Enzyme inhibitors; Ganglia; Gastrointestinal Motility - drug effects; Gastrointestinal Transit - drug effects; Intestinal Mucosa - drug effects; Intestinal Mucosa - metabolism; Intestine; Ion Transport - drug effects; Irritable bowel syndrome; Male; Motility; Mucosa; Neostigmine; Proto-Oncogene Proteins c-ret - antagonists & inhibitors; Proto-Oncogene Proteins c-ret - metabolism; Rats; Rats, Sprague-Dawley; RET; Secretion; Signal Transduction - drug effects
• ISSN: 1350-1925; 1365-2982
• DOI: 10.1111/nmo.13479

Background The expression of RET in the developing enteric nervous system (ENS) suggests that RET may contribute to adult intestinal function. ENS cholinergic nerves play a critical role in the control of colonic function through the release of acetylcholine (ACh). In the current study, we hypothesized that a RET‐mediated mechanism may regulate colonic ion transport and motility through modulation of cholinergic nerves. Methods The effect of RET inhibition on active ion transport was assessed electrophysiologically in rat colonic tissue mounted in Ussing chambers via measurements of short circuit current (Isc) upon electrical field stimulation (EFS) or pharmacologically with cholinergic agonists utilizing a gastrointestinal (GI)‐restricted RET inhibitor. We assessed the effect of the RET inhibitor on propulsive motility via quantification of fecal pellet output (FPO) induced by the acetylcholinesterase inhibitor neostigmine. Key Results We found that enteric ganglia co‐expressed RET and choline acetyltransferase (ChAT) transcripts. In vitro, the RET kinase inhibitor GSK3179106 attenuated the mean increase in Isc induced by either EFS or carbachol but not bethanechol. In vivo, GSK3179106 significantly reduced the prokinetic effect of neostigmine. Conclusion and Inferences Our findings provide evidence that RET‐mediated mechanisms regulate colonic function by maintaining cholinergic neuronal function and enabling ACh‐evoked chloride secretion and motility. We suggest that modulating the cholinergic control of the colon via a RET inhibitor may represent a novel target for the treatment of intestinal disorders associated with increased secretion and accelerated GI transit such as irritable bowel syndrome with diarrhea (IBS‐D). In the current study, we hypothesized that a RET‐mediated mechanism may regulate colonic ion transport and motility through modulation of cholinergic nerves. Our findings provide evidence that RET‐mediated mechanisms regulate colonic function by maintaining cholinergic neuronal function and enabling ACh‐evoked chloride secretion and motility. We suggest that modulating the cholinergic control of the colon via a RET inhibitor may represent a novel target for the treatment of intestinal disorders associated with increased secretion and accelerated GI transit such as irritable bowel syndrome with diarrhea (IBS‐D).