ILEOCECAL JUNCTION MOTILITY DISORDER IN THE HORSE - A HYPOTHESIS OF THE PATHOGENESIS OF INTUSSUSCEPTION OF THE ILEUM IN THIS SPECIES

In the thorse, the tonus of the ileal sphincter and the ileal peristal sis hindered the reflux of caecal content into the ileum. The tonus of the ileal sphincter was reinforced by the stimulation of alpha1 adren ergic receptors. Serotonin increased ileal peristalsis. This excitomot or serotonin effect corresponded to a stimulation of 5-HT2 receptors. Nicergoline (an alpha1 adrenergic blocking agent) stimulated ileal per istalsis, by inhibiting the tonic activity of the sphincter. This last result suggested that, in case of a decrease in the sphincter tonus, the reflux of caecal content into the ileum could be enhanced, and thu s exacerbate, by a reflex route, ileal peristalsis. The amplification of this phenomenom could induce intussusception of the ileum into the caecum.