GSK962040: a small molecule, selective motilin receptor agonist, effective as a stimulant of human and rabbit gastrointestinal motility

Gastroduodenal motility

PURPOSE OF REVIEW

Abnormalities of gastroduodenal motility are considered key players in the pathogenesis of upper gastrointestinal symptoms in disorders such as functional dyspepsia and gastroparesis. Abnormalities of sensory control are considered another important factor that contributes to symptom generation. This review summarizes recent progress in our understanding of gastroduodenal motility and sensitivity in health and in disease.

RECENT FINDINGS

Although gastric and small intestinal motility remain an important focus of research, including the application of the SmartPill (SmartPill Corp., Buffalo, New York, USA) wireless motility monitoring capsule, duodenal sensitivity and low-grade duodenal inflammation are new areas of interest in the pathogenesis of functional dyspepsia. A number of genetic polymorphisms associated with functional dyspepsia are being investigated, but large-scale studies are still lacking. Central processing of visceral stimuli, and its role in the pathogenesis of functional dyspepsia, is another important emerging topic. Therapeutic studies have reported on novel pharmacological approaches in functional dyspepsia and gastroparesis, as well as gastric electrical stimulation in the treatment of refractory gastroparesis.

SUMMARY

There is gradual progress in our understanding of the pathogenesis of gastroduodenal symptoms. Areas of recent advances including the recognition of low-grade duodenal inflammation, the role of central nervous system processing in visceral hypersensitivity and the exploration of novel pharmacotherapeutic approaches.

Challenges and prospects for pharmacotherapy in functional gastrointestinal disorders

Functional gastrointestinal disorders, such as irritable bowel syndrome and functional dyspepsia, are complex conditions with multiple factors contributing to their pathophysiology. As a consequence they are difficult to treat and have posed significant challenges to the pharmaceutical industry when trying to develop new and effective treatments. This review provides an overview of these difficulties and how the industry is reshaping its drug developmental strategies. It describes some of the more significant and encouraging advances that have occurred, and discusses how future research might embrace the opportunities provided by advances in genetic and in particular, epigenetic research.

Integrating GHS into the Ghrelin System

Oligopeptide derivatives of metenkephalin were found to stimulate growth-hormone (GH) release directly by pituitary somatotrope cells in vitro in 1977. Members of this class of peptides and nonpeptidyl mimetics are referred to as GH secretagogues (GHSs). A specific guanosine triphosphatate-binding protein-associated heptahelical transmembrane receptor for GHS was cloned in 1996. An endogenous ligand for the GHS receptor, acylghrelin, was identified in 1999. Expression of ghrelin and homonymous receptor occurs in the brain, pituitary gland, stomach, endothelium/vascular smooth muscle, pancreas, placenta, intestine, heart, bone, and other tissues. Principal actions of this peptidergic system include stimulation of GH release via combined hypothalamopituitary mechanisms, orexigenesis (appetitive enhancement), insulinostasis (inhibition of insulin secretion), cardiovascular effects (decreased mean arterial pressure and vasodilation), stimulation of gastric motility and acid secretion, adipogenesis with repression of fat oxidation, and antiapoptosis (antagonism of endothelial, neuronal, and cardiomyocyte death). The array of known and proposed interactions of ghrelin with key metabolic signals makes ghrelin and its receptor prime targets for drug development.