Receptors on Autonomic Neurons and Neuroeffector Cells: Peptidergic Receptors.

Neuropeptides are peptides involved in various nervous system functions. They are synthesized in cells as large precursor proteins, and generally several biologically active peptides are contained in the same precursor molecule. Peptidergic signaling molecules are widely distributed throughout the central and peripheral nervous systems and in peripheral organs. They act by neurocrine, paracrine, autocrine and endocrine mechanisms and the same peptides may participate in inter-cellular communications through different modalities. For instance, many peptides expressed in the enteric nervous system belong to a class of agents known as brain-gut peptides, functioning both as neuropeptides and as gut hormones.