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Physiology of Pregnancy
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
During pregnancy, the stomach and intestines are displaced cephalad by the gravid uterus. Progesterone relaxes smooth muscles and inhibits the contractile response of the gastrointestinal tract to acetylcholine and gastrin. These factors are important for changes in the gastrointestinal tract during pregnancy. The lower oesophageal sphincter (LOS) tone progressively decreases and, with changes in the angle of the gastro-oesophageal junction, the LOS becomes incompetent and results in gastric reflux. This makes pregnant women more prone to pulmonary aspiration during general anaesthesia. Gastric motility is reduced, and there is delayed gastric emptying at 12–14 weeks of gestation. Further prolongation of gastric emptying occurs during labour as a result of anxiety and pain. Gastrin production progressively increases during pregnancy, as it is produced by the placenta. Gastrin stimulates the secretion of water and enzymes from the gastrointestinal tract. Gastric acid production is increased during the third trimester. Administration of opioids during the post-partum period delays gastric emptying. The motility of the small and large intestines is reduced due to a reduced plasma concentration of motilin. In the second and third trimesters, the contractility of the gall bladder is reduced as a result of the diminished release of cholecystokinin from intestinal mucosa caused by progesterone.
Motilin and Gastric Inhibitory Polypeptide (GIP)
Published in Craig A. Johnston, Charles D. Barnes, Brain-Gut Peptides and Reproductive Function, 2020
A number of studies have demonstrated that motilin can act both directly on smooth muscle and via interaction with intrinsic gastrointestinal nerves. In addition, there is species specificity in smooth muscle responses to motilin with rat tissues, in particular, being refractory to porcine motilin (McIntosh and Brown, 1989, 1990). The canine duodenum contracted in response to both porcine and canine motilins in vivo (Itoh et al., 1990) but only to canine motilin in vitro (Poitras et al., 1987a).
Gastrointestinal Aspects of Eating Disorders
Published in Kevin W. Olden, Handbook of Functional Gastrointestinal Disorders, 2020
Bruce D. Waldholtz, Arnold E. Andersen
In addition, erythromycin has been shown to improve gastric emptying in diabetic gastroparesis, but has not been studied in gastroparesis associated with anorexia nervosa. It improves gastric emptying for solids and liquids by acting as a motilin-receptor agonist, a hormone responsible for phase III contractions during the intradigestive motor complex (38). While studies demonstrate that these agents can improve gastric emptying in patients with gastroparesis from diabetes or possibly in anorexia nervosa, the routine use of these agents cannot be recommended in anorexia nervosa until studies demonstrate them to be effective. On a case-by-case basis, cisapride may be usefully employed.
Gastroparesis syndromes: emerging drug targets and potential therapeutic opportunities
Published in Expert Opinion on Investigational Drugs, 2023
Le Yu Naing, Matthew Heckroth, Prateek Mathur, Thomas L Abell
There are a few medications that have successfully been used as off-label treatments for GpS. Erythromycin is a macrolide antibiotic that has a prokinetic effect on the GI tract by activating the motilin receptor. Motilin is a peptide synthesized and released in the small intestine, with smaller amounts in the gastric antrum, during fasting and postprandial phases. It acts on motilin receptors to stimulate gastric contractions and increase gastric emptying. Another macrolide, azithromycin, has also demonstrated activity as a motilin receptor agonist, although data is limited. Although not FDA approved for GI motility disorders, erythromycin has been widely used in the acute treatment of Gp. Due to concerns with tachyphylaxis, the risk of antibiotic resistance, poor availability of oral formulation, and its tendency for QT prolongation, long-term use is not widely recommended.
Motilin Receptor Expression Found in the Human Main and Accessory Lacrimal Glands
Published in Ocular Immunology and Inflammation, 2022
Richard R. Sadig, Alexandra Allende, Geoffrey Hall, Dinh Tran, Michele C Madigan, Stephanie L. Watson, Kenneth G. -J. Ooi
The motilin receptor is an important prokinetic receptor traditionally found in the antrum of the stomach as well as the duodenum.5 Motilin is a 22 amino acid ligand hormone secreted mainly by specialized enterochromaffin mucosal cells of the upper GIT system including the stomach antrum and the duodenum. Its secretion is usually in response to changes in the pH of the stomach, alkalinization of the duodenum and distention of the stomach.6–8 The actions of motilin also affect the cholinergic pathway to stimulate contractions of the gall bladder and the sphincter of Oddi.7 The motilin receptor is a guanine-coupled receptor of class 1 type 1. The motilin receptor has two main bindings site identified, an extracellular portion and a transcellular portion. The extracellular portion involves the docking of peptide-like structures (such as motilin) onto the extramembranous loop portion of the motilin receptor.9 Motilin is released with cholinergic vagal stimulation of local antral nerve plexuses.10 This suggests that motilin can be released both in local response and via central neuronal control – predominantly under cholinergic control.8,10 Motilin receptors have also been found in rabbit brains– with the highest densities found in the hippocampus, hypothalamus and amygdala, as well as in the cerebellum.4,11 Its role in the central nervous system is not entirely clear but it is postulated to be involved with neurotransmission via synaptosomes, as well as stimulating appetite, mood and memory6,11,12,13
Acupoint Massage Can Effectively Promote the Recovery of Gastrointestinal Function after Gynecologic Laparoscopy
Published in Journal of Investigative Surgery, 2021
Di Ruan, Jingjing Li, Junchang Liu, Dandan Li, Ning Ji, Cheng Wang, Yujiang Qu, Yongtao Li
The vagus nerve of the autonomic nervous system regulates gastrointestinal motility by stimulating the release of different gastrointestinal hormones [14]. Motilin is among the one that promotes the motility of gut intestine during digestion [15], and indeed, motilin is one of the indicators that have been clinically used to evaluate postoperative gastrointestinal function [16]. In past few years, the functional relationship between the meridian and autonomic nervous systems has been extensively studied. Acupoint massage was shown to modulate both heart rate variability and meridian electrical conductance [17]. Enhanced qi circulation is believed to promote the stimulating effect of the vagus nerve on gut motility. In accordance to this hypothesis, our data showed that the qi-promoting massage could profoundly elevate not only motilin but also cholecystokinin. Cholecystokinin mediates digestion in the small intestine, and stimulates digestive enzyme releases from the pancreas [18]. Somatostatin suppresses the release of gastrointestinal hormones including motilin and cholecystokinin [19]. Here, we showed that the acupoint massage could reduce somatostatin level in patients, resulting in the up-regulation of digestion-promoting hormones.