Calcitonin--C.N.S. Action to Control the Pattern of Intestinal Motility in Rats

Synthetic calcitonin injected into the lateral ventricles (ICV) of rats at picomolar concentration restores the "fasted' motility pattern of the small intestine in fed rats at doses as low as 0.083 picomoles. This effect which appeared in less than 5 min and persisted at least 2 hours for 0.83 picomole, was blocked by a previous intraventricular administration of 10 micrograms/ of calcium gluconate. At 0.83 picomole ICV, calcitonin also suppressed the disruption of the "fasted' pattern induced by intravenous infusion of Pentagastrin (6 micrograms.kg-1.h-1) but not that induced by insulin (0.5 U.kg-1). These findings support the hypothesis that calcitonin acts centrally to control the pattern of intestinal motility by inhibiting the digestive influences responsible for the "fed' pattern. All of these peripheral influences are mediated by a Ca++ sensitive central structure.