Peptide Neurotransmitters and Hormones

Miguel A Gonzalez‐Lozano, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
Ka Wan Li, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands

Published online: May 2020

DOI: 10.1002/9780470015902.a0000063.pub3

Abstract

Neuropeptides are a structurally diverse class of chemical messengers that play important roles in the coordination of many physiological and behavioural events. Neuropeptides are derived from the cleavage of larger precursor proteins at the dibasic amino acid sites by prohormone convertases. They are synthesised in the cell body, packaged in the large dense core vesicles and released in a neuronal activity‐dependent manner. The neuropeptides may function as blood‐borne hormones or as mediators/transmitters affecting neuronal activity in the nervous system. In the target cells, neuropeptides activate the complementary G protein‐coupled receptors and elicit responses that are specific to these cells. The released peptide is subsequently inactivated by the actions of several nonspecific extracellular peptidases.

Key Concepts

  • Neuropeptides are a structurally diverse class of chemical messengers produced by nerve cells to coordinate many physiological and behavioural processes.
  • The major neuroendocrine centre in the brain is the pituitary gland.
  • Neuropeptides are derived from the cleavage of the larger precursor proteins by specific endoproteases that are copackaged in the dense core secretory granules.
  • Receptors for neuropeptides belong mainly to the family of G protein‐coupled receptor.
  • G protein‐coupled receptor may be activated in complex modes beyond their interaction with G proteins.

Keywords: peptides; biosynthesis; function; degradation; endocrine/neuronal communication

Figure 1. In situ hybridisation (ISH) of mouse brain reveals regional expression pattern of neuropeptides. The images and data are generated from Allen Brain Atlas mouse brain ISH data (http://mouse.brain‐map.org/) for (a) PACAP, (b) Cholecystokinin and (c) Oxytocin. Panels from left to right show the ISH images, the expression images and the quantified expression of the neuropeptide in each brain regions. Adapted from Allen Brain Atlas.
Figure 2. Schematic diagram of the biosynthesis of peptide transmitter/hormone and its effects on the target cell. The mRNA encoding the peptide precursor is transcribed in the nucleus and translated at the rough endoplasmic reticulum into a biological inactive precursor protein. The precursor protein is transported to the Golgi apparatus (Golgi) and packaged into the dense core secretory granules for further proteolytic processing and storage. Exocytosis of secretory granule releases the biological active peptides. When the peptide binds to its receptor (GPCR) in the target cell, it dissociates the Gα from Gβ and Gγ and activates the corresponding downstream effector proteins. In addition to the classic G proteins routes, GPCR activation can involve other signalling pathways such as β‐arrestin. The peptide–receptor interaction also initiates desensitisation through receptor endocytosis. The receptor could recycle back to the plasma membrane for another round of receptor activation.
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Further Reading

Van den Pol A (2012) Neuropeptide transmission in brain circuits. Neuron 76: 98–115.

Wang W, Qiao Y and Li Z (2018) New insights into modes of GPCR activation. Trends in Pharmacological Sciences 39: 367–386.

Related Sub-Topics:

Neurotransmitters | Receptors for Neurotransmitters | Intracellular and Extracellular Signalling | Cellular Transport | Cell Signalling
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Article Title: Peptide Neurotransmitters and Hormones
 
How to Cite close
Gonzalez‐Lozano, Miguel A, and Li, Ka Wan(May 2020) Peptide Neurotransmitters and Hormones. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0000063.pub3]