Plasticity of vagal brainstem circuits in the control of gastric function

Here, we review the available evidence suggesting that vagal efferent output to the GI tract is regulated, perhaps even controlled, in an 'on-demand' and efficient manner in response to ever-changing homeostatic conditions. The focus of this review is on the plasticity induced by variations in the levels of second messengers in the brainstem neurons that form vago-vagal reflex circuits. Emphasis is placed upon the modulation of GABAergic transmission to DMV neurons and the modulation of afferent input from the GI tract by neurohormones/neurotransmitters and macronutrients. Derangement of this 'on-demand' organization of brainstem vagal circuits may be one of the factors underlying the pathophysiological changes observed in functional dyspepsia or hyperglycemic gastroparesis.