THE NEUROENDOCRINE CONTROL OF GASTROINTESTINAL MOTOR-ACTIVITY

Here we describe interactions between peptide hormones and the enteric, autonomic and central innervation, and to the regulation of some major digestive events. The neuronal functions, the variety of neurochemically distinct neurons and some recent results on chemical marker combinations in the neurons are mentioned. A classification of the substances potentially acting as neurotransmitters or neuromodulators of gut motility is also reported. The major motor events taken into account include the migrating motor complex, the peristaltic reflex. the gastric emptying and the gallbladder/sphincter of Oddi relationships. The demonstration that numerous peptides may be detected in. and secreted by, the neurons has opened a fascinating area of study. Various difficulties hampering the comprehension of modalities according to which gastrointestinal motility is regulated, are discussed. Experimental evidence however, has to be considered cautiously. Expressions such as 'the peptidergic control of motility' may suggest that these peptides are the primary subjects in the strategy leading to the motor events, rather than the transmitters of impulses whose strategy is decided at higher levels. The autonomy of the peripheral regulatory system is apparent in certain conditions and has an important supplementary value. In general. however, the neuroendocrine regulation remains a global phenomenon testifying the unity of the living organism.