Molecular Signaling in the Gut–Brain Axis in Stress

Abstract The bidirectional communication between the gastrointestinal tract (GI) and the brain is termed the gut–brain axis. It involves endocrine and neural pathways (parasympathetic nerves and sympathetic nerves) and interactions with the GI immune system and the gut microbiota. The gut–brain axis plays a crucial role in the modulation of the physiological functioning of the GI tract and the brain. This complex communication system is extremely sensitive to stress. In response to stress the molecular signaling in the gut–brain axis can be altered, in both descending and ascending pathways. The alterations can be adaptive responses, allowing the body to cope with environmental threats and maintain homeostasis. However, it can also lead to malfunctions in the GI tract and brain contributing to the development of many GI and brain associated disorders.