Neuropeptides

Neuropeptides are small protein-like molecules (peptides) used by neurons to communicate with each other. They are neuronal signaling molecules that influence the activity of the brain and the body in specific ways. Different neuropeptides are involved in a wide range of brain functions, including analgesia, reward, food intake, metabolism, reproduction, social behaviors, learning and memory.

Structure and Function

Neuropeptides are typically composed of between 3 and 36 amino acids, and are often post-translationally modified. They are synthesized from larger precursor proteins, which are cleaved into the active neuropeptide. Neuropeptides are stored in vesicles and are released into the synaptic cleft by high-frequency neuronal firing.

Neuropeptides exert their effects by binding to specific cell surface receptors. These can be either G-protein coupled receptors or ionotropic receptors. The binding of a neuropeptide to its receptor initiates a cascade of intracellular events, which can result in changes in neuronal excitability, gene expression, or synaptic plasticity.

Types of Neuropeptides

There are many different types of neuropeptides, including endorphins, enkephalins, dynorphins, orexins, vasopressin, oxytocin, somatostatin, neuropeptide Y, cholecystokinin, gastrin-releasing peptide, neurotensin, substance P, corticotropin-releasing hormone, melanocyte-stimulating hormone, thyrotropin-releasing hormone, gonadotropin-releasing hormone, and growth hormone-releasing hormone.

Role in Disease

Alterations in neuropeptide function or expression can contribute to a variety of diseases, including neurodegenerative diseases, psychiatric disorders, cancer, pain, cardiovascular diseases, and obesity. For example, mutations in the gene encoding the neuropeptide orexin are associated with narcolepsy, a sleep disorder.

Therapeutic Potential

Because of their role in disease, neuropeptides are potential targets for therapeutic intervention. Several drugs that target neuropeptide systems are already in clinical use, and many more are under development. For example, drugs that target the endogenous opioid system (including endorphins, enkephalins, and dynorphins) are used for pain relief.

See Also

• Neurotransmitter
• Peptide hormone
• Signal transduction

References

Neuropeptides Resources
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