VAGAL CONTROL OF DIGESTION - MODULATION BY CENTRAL NEURAL AND PERIPHERAL ENDOCRINE FACTORS

Vago-vagal reflex control circuits in the dorsal vagal complex of the brainstem provide overall coordination over digestive functions of the stomach, small intestine and pancreas. The neural components forming these reflex circuits are under significant descending neural control. By adjusting the excitability of the different components of the refl ex, alterations in digestion control can be produced by the central ne rvous system. Additionally, the dorsal vagal complex is situated withi n a circumventricular region without an effective ''blood-brain barrie r''. As a result, vago-vagal reflex circuitry is also exposed to humor al influences which profoundly alter digestive functions by acting dir ectly on brainstem neurons. Behavioral and endocrine physiological obs ervations suggest that this ''humoral afferent pathway'' may significa ntly alter the regulation of food intake.