Fig. 1.

Gut–brain communication through gut peptides. Gut peptides are released from enteroendocrine cells in response to preabsorptive nutrients and act to relay information regarding incoming energy to the brain. Once released into the subcellular space, gut peptides can act locally on gut peptide receptors expressed on vagal or spinal afferent nerve terminals innervating the gut to activate gut–brain neuronal signaling. Gut peptides might also act indirectly via receptors on intrinsic neurons of the enteric nervous system to relay neuronal signaling to afferent nerves. In contrast, gut peptides can diffuse into the systemic circulation or lymphatics to eventually reach the brain and act on central receptors in an endocrine fashion