receptors occur in peripheral nervous system, especially nociceptive afferent neurons and
enteric neurons and in CNS, chiefly in the area postrema (a region of the
medulla involved in vomiting) and other parts of the brainstem, extending to the dorsal
horn of the spinal cord. They are also widely, but more sparsely, present in certain parts
of the cortex. Effects are excitatory, mediated via direct receptor-couped
5-HT4 – receptors occur mainly in the enteric nervous system
(also in CNS). Effects are excitatory, causing increased gastrointestinal motility. Acts
by stimulation adenylate cyclase.