RHYTHMIC OSCILLATING COMPLEXES IN GASTROINTESTINAL-TRACT OF CHICKENS - A ROLE FOR MOTILIN

Rhythmic oscillating complex (ROC) is a highly organized gastrointesti nal motility pattern recently described in fasted avian species. ROCs show several high-speed aborad-propagated contractions that progressiv ely change into others of orad direction. In addition, chickens show m igrating motor complexes (MMC) in both fed and fasting states. Recentl y, motilin was isolated and characterized from chicken small intestine . Accordingly, the aim of this study was to learn whether chicken moti lin might be involved in either ROC or MMC induction. Electromyographi c recordings were obtained from different areas of the gastrointestina l tract of chickens while motilin was infused. The response to chicken motilin was dose dependent in both fed and fasted animals; a bolus of 4 x 10(-11) mol/kg (n = 5) did not modify the intestinal motor patter n, whereas 4 x 10(-10) and 4 x 10(-9) mol/kg(n = 5 each) induced a com plete ROC pattern of 5.2 +/- 0.6 and 10.8 +/- 0.9 min, respectively. R OCs induced by chicken motilin presented exactly the same pattern as t hat described during a spontaneous ROC. Furthermore, motilin concentra tion in plasma, measured by radioimmunoassay, increased during a spont aneous ROC. This study suggests that chicken motilin triggers an ROC i n chickens. The fact that plasma motilin levels increased during spont aneous ROC strongly suggests that motilin is involved in the induction of the ROC pattern. Motilin seems to play a different role in avian a nd mammalian species, because a phase III of the MMC was never induced by motilin infusion.