[Implication of melatonin in the control of the interdigestive ileocecal-colic electromyographic profile in rats].

In the interdigestive period, intestinal motility displays myoelectrical complexes occurring cyclically at a constant rhythm. Since it is established that the pineal gland plays an important role in the control of circadian rhythms via its melatonin secretion, we decided to study the effects of pinealectomy and melatonin on the organization of the ileo-ceco-colic electromyogram of the rat. Pinealectomy resulted in the disappearance of ileal myoelectrical complexes and, concurrently, an excitomotor effect on the cecocolic tract. In pinealectomized rats a single intravenous injection of melatonin during lighting period induced an immediate recovery of the ileal myoelectrical complexes and a progressive return to the control electromyographic pattern of the ceco-colic tract. The melatonin action was definitive.