Figure 1.

Interaction of the central nervous system (CNS), enteric nervous system (ENS), the gastrointestinal (GI) tract, and the gut microbiota in normal and stress conditions. In each case, the interaction is bidirectional and can be mediated by many factors; some of them are shown. Stress conditions may influence, directly or indirectly, CNS, gut, and microbiota, resulting in psychoneurological disorders and functional GI diseases (FGIDs). The stress may also result in organic GI or CNS diseases, which are not subjected to this review.