• A member of a class of protein-like molecules made in the brain. Neuropeptides consist of short chains of amino acids, with some functioning as neurotransmitters and some functioning as hormones.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• Peptides released by neural tissue as intercellular messengers; many are also hormones released by non-neuronal cells.
  CRISP Thesaurus
  National Institutes of Health, 2006
• Peptides with direct synaptic effects or indirect modulatory effects on the nervous system. A neuropeptide is a molecule released by neurons as an intercellular neurotransmitter. Alternatively, neuropeptides can be released by non-neuronal cells as hormones. They are endogenous peptides such as endorphins that influence neural activity or functioning.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• Peptides released by NEURONS as intercellular messengers. Many neuropeptides are also hormones released by non-neuronal cells.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2021
• Small proteins that aid in transmitting signals between nerve cells.
  Harvard Dictionary of Health Terms
  Harvard Medical Publishing, 2011