Central actions of calcitonin on body temperature and intestinal motility in rats: evidence for different mediations

The effects of intracerebroventricular (i.c.v.) administration of calcitonin and PGE2 on intestinal motility and body temperature were examined in conscious rats chronically fitted with intraparietal electrodes in the small intestine, a cannula in a cerebral lateral ventricle and a subcutaneous thermistor probe. Both calcitonin and PGE2 restored the fasted pattern of intestinal motility in fed rats and induced an increase in body temperature. Indomethacin, an inhibitor of the cyclooxygenase with calcium antagonistic properties, and TMB-8, an intracellular calcium antagonist, blocked the effects of calcitonin on intestinal motility and body temperature. Piroxicam, an inhibitor of the cyclooxygenase which does not affect calcium uptake blocked the thermic but not the intestinal effects of calcitonin. TMB-8 but not indomethacin or piroxicam partially blocked the effects of PGE2 on both intestinal motility and body temperature. It is concluded that the central hyperthermic effect of calcitonin is mediated through the formation and the release of prostaglandins whereas the central action of calcitonin on digestive motility results from intracerebral effects on calcium fluxes.