GABA and Gut Motility

Motility in the gut is a complex series of movements with an underlying orderliness that ensures descending propulsion of the intestinal contents.Prominent amongst these are rhythmic contractile activity and coordinated descending waves of contraction and relaxation. Rhythmic activity can occur in the absence of obvious stimulation but probably has a mixing function, whereas propulsive activity is triggered by distension or by chemical stimulation of the mucosa. There is an obvious polarity in the propulsive activity; contractions occur above the stimulated region and relaxation below. This is the basis of the peristaltic reflex [3] which persists in extrinsically denervated gut segments having no connections with the central nervous system. Indeed, isolated segments continue to exhibit a range of motility, including the peristaltic reflex, even when totally removed and maintained in artificial media. Such isolated preparations lend themselves to pharmacological investigation and have formed the basis of our studies on GABA involvement in motility patterns of the gut.