Neuropeptide
Neuropeptides produce a prolonged action. Neurotransmitters trigger short-term responses.
Neuropeptides act on a number of receptor proteins. Most neurotransmitters only act on a specific receptor.
🤖 AI addition (14/06/26):
What is a Neuropeptide?
A neuropeptide is a short chain of amino acids (3–40+) synthesized by neurons that acts as a signaling molecule. Unlike classical neurotransmitters, neuropeptides are released into the extracellular space and diffuse broadly — a mechanism called volume transmission — modulating entire networks rather than single synapses.
Synaptic vesicle types — neuropeptides in large dense-core vesicles (LDCVs) vs small clear vesicles for classical NTs (Wikimedia Commons, CC BY-SA)
Neuropeptide synthesis: prepropeptide → cleavage in ER → Golgi processing → dense-core vesicle → release (based on Nestler et al., Molecular Pharmacology 2009; Wikimedia Commons, CC BY-SA 3.0)
Synthesis & Release
- Gene expression in cell soma → prepropeptide (large precursor protein)
- Cleavage in the endoplasmic reticulum → propeptide
- Post-translational processing in Golgi apparatus (cleaving, glycosylation, amidation)
- Packaged into large dense-core vesicles (LDCVs) — bigger and darker than regular synaptic vesicles
- Transported along axons to terminals, but also released at cell bodies and along axons (not just at synapses)
- Released by high-frequency firing or burst activity (higher Ca²⁺ threshold than classical NTs)
Key Properties
| Property | Neuropeptide | Classical Neurotransmitter |
|---|---|---|
| Size | 3–40+ amino acids | Small molecule |
| Vesicle type | Large dense-core vesicle | Small clear vesicle |
| Release site | Synapses, soma, axon en passant | Synaptic terminal only |
| Diffusion range | Wide (volume transmission) | Narrow (synaptic cleft) |
| Effect duration | Minutes to hours | Milliseconds to seconds |
| Receptor types | Multiple (often GPCRs) | Often more specific |
| Degradation | Enzymatic cleavage (peptidases) | Reuptake or enzymatic |
Subtypes
Neuropeptides can also act as hormones when released into the bloodstream — this dual function is one of the most important features of this class:
- Hypothalamic releasing hormones — CRH (CRH), LHRH (LHRH) — control the pituitary
- Pituitary hormones — Growth Hormone, Prolactin — released into blood
- Social neuropeptides — Oxytocin, Vasopressin — act locally in brain and as hormones in blood
- Opioid neuropeptides — Endorphins, enkephalins, dynorphin — pain modulation, reward
- Gut-brain peptides — Ghrelin (hunger), CCK (satiety), Substance P (pain)
Examples from the Vault
| Neuropeptide | Primary Function | Vault Note |
|---|---|---|
| Oxytocin | Bonding, trust, prosociality | Oxytocin |
| Vasopressin | Monogamy, paternal behavior, social memory | Vasopressin |
| Endorphins | Pain inhibition, runner’s high | Endorphins |
| CRH | Stress response initiation (→ ACTH) | CRH |
| LHRH | Reproductive hormone release | LHRH |
Why Neuropeptides Are Evolutionarily Ancient
Neuropeptide signaling predates classical neurotransmitter systems. Peptide signaling is found in almost all animals, including simple invertebrates without a full nervous system. This suggests peptide-based communication was the original intercellular signaling mode, with small-molecule NTs evolving later for faster, more localized signaling.
Clinical Relevance
- Pain — opioid neuropeptides (Endorphins) are the targets of morphine and all opioid drugs
- Stress disorders — CRH antagonists are being studied for depression/PTSD
- Autism/social behavior — oxytocin nasal spray research for social deficits
- Appetite regulation — GLP-1 (a gut neuropeptide) is the basis of Ozempic/semaglutide
see also
Tags: neuroscience HormoneNeurotransmitter science
Superlink: 052 🫧Hormone und Neurotransmitter 051 ☣Neurobiology 050 🧠Neuroscience
Linked notes: Neurotransmitter · Neurotransmitter vs Neuropeptide vs Hormone · Oxytocin · Vasopressin · Endorphins · CRH · LHRH · Growth Hormone · Prolactin
Source
Neuropeptide – Wikipedia
Large Dense Core Vesicles – Wikipedia
Created: 01-02-24 16:24
Erweitert: 14/06/26