Galanin: natural brain peptide that calms pain and nerve activity
A hormone made naturally in the brain and gut that damps down nerve signals, easing nerve-related pain and helping control seizures; used as a lab research tool, not an approved drug.
A researcher, an agent, or an algorithm wrote down the sequence and picked a target to hit.
An AI model like OpenFold3 or AlphaFold built a 3D structure and scored how well it fits the binding site.
A second contributor repeated the computation on their own hardware and the scores matched.
A chemistry service or a researcher ordered the sequence, it was manufactured, and mass spectrometry confirmed the right molecule was produced.
A binding or activity measurement confirmed that it actually does what the computer predicted — or didn't.
What this is
Galanin is a brain and gut signaling peptide that the body makes naturally. Human galanin is 30 amino acids long and is found throughout the central and peripheral nervous system, where it dampens nerve cell activity in regions tied to pain, mood, seizures, memory, and feeding (Webling 2012). The human form differs from the rat and bovine versions in one important chemical detail — where rat and bovine galanin are 29 residues long and amidated at the C-terminus, the human peptide is 30 residues long and is not amidated (Schmidt 1991). Researchers study galanin and its receptors as potential targets for epilepsy, neuropathic pain, anxiety, and metabolic disease (Freimann 2015).
History
Galanin was first identified in 1983 from porcine intestine, and the rat and bovine forms were sequenced soon after from their cDNA. The human sequence was harder to obtain because the peptide is present at low abundance — it took Schmidt and colleagues (1991) extracting 280 postmortem human pituitaries in trifluoroacetic acid and running three successive HPLC purifications, guided by a radioreceptor assay, before they could Edman-sequence the intact peptide. They reported a 30-residue, non-amidated structure, which was confirmed in the same year by molecular cloning of the human galanin precursor (Evans 1991). A second receptor (GalR2) was cloned in 1997 (Wang 1997), and a third (GalR3) in 1998 (Smith 1998), completing the three-receptor family galanin acts through.
What it does
Galanin binds three G-protein-coupled receptors — GalR1, GalR2, and GalR3 — that are coupled mostly to inhibitory Gi/o-type G proteins. The net effect at most synapses is quieter nerve cells: galanin reduces neurotransmitter release and decreases firing in hippocampus, amygdala, and spinal cord neurons, which is why it has anticonvulsant and antinociceptive effects in animal models (Kapur 2011; Freimann 2015). In the pancreas, galanin suppresses insulin release from β cells, an effect mediated through the Gαo2 subtype of Gi/o-family G proteins (Tang 2012). The peptide also influences feeding behavior, learning and memory, and anxiety-related behaviors (Tang 2012; Webling 2012).
Mechanism
The full 30-residue human peptide (hGal 1–30) binds GalR1, GalR2, and GalR3 with low-nanomolar affinity at all three subtypes (Freimann 2015). Most signaling proceeds through Gi/o-family G proteins, lowering cAMP and modulating downstream ion channels — the canonical Gi/o pathway behind the peptide's inhibitory effects on neuronal firing (Webling 2012). The pancreatic β-cell inhibition of insulin release maps specifically onto the Gαo2 subtype rather than the broader Gαi pool, which Tang and colleagues (2012) showed using subtype-selective knockouts. The N-terminal region of galanin carries most of the receptor-binding pharmacophore: truncated fragments such as galanin(2–11) retain binding at GalR3, although with caveats about pharmacological subtype selectivity in transfected cell lines (Lu 2005).
Evidence
- Human: Galanin's structure, distribution, and receptor pharmacology have been characterized from human tissue (Schmidt 1991; Evans 1991), and galanin-receptor pharmacology has been mapped on cloned human GalR1/2/3 (Wang 1997; Smith 1998; Freimann 2015). No published clinical trials of the native human peptide as a therapeutic.
- Animal: Anticonvulsant effects in rodent seizure models and a role for galanin receptors in modulating seizure thresholds are reviewed in Kapur (2011). Inhibition of insulin release from pancreatic β cells via Gαo2 demonstrated in genetically modified mice (Tang 2012).
- In vitro: Binding affinities for GalR1, GalR2, and GalR3 reported in transfected cell lines (Freimann 2015; Webling 2012). GalR3 binding by the galanin(2–11) fragment characterized in transfected lines, with the authors flagging assay-dependent limits on subtype-selectivity claims (Lu 2005).
Known effects
- Anticonvulsant activity — Preclinical (rodent seizure models, reviewed in Kapur 2011)
- Antinociceptive activity — Preclinical, primarily through spinal cord GalR1 (Freimann 2015)
- Suppression of insulin release — Preclinical, Gαo2-mediated in β cells (Tang 2012)
- Modulation of feeding and metabolism — Mechanistic / preclinical (Tang 2012; Webling 2012)
- Effects on learning, memory, and anxiety-related behavior — Mechanistic / preclinical (Tang 2012; Webling 2012)
Regulatory status
- US / EU: Not an approved drug. Galanin and its receptor agonists/antagonists are investigational research tools; no human therapeutic has reached approval.
- WADA: Not specifically listed as the native peptide.
Open questions
- Whether any galanin-receptor-selective ligand (rather than the pan-GalR native peptide) can be advanced into clinical development for epilepsy, neuropathic pain, or anxiety (Freimann 2015).
- The degree of true pharmacological subtype selectivity of galanin fragments in vivo versus in transfected lines (Lu 2005).
- The relative contribution of GalR1, GalR2, and GalR3 to each of galanin's many physiological effects, given heavy co-expression and overlapping signaling (Webling 2012).
Research directions for this peptide, selected from the current sources — hypotheses you can explore and model. None of it is proven yet; tap any one to see the full thinking.
Does galanin really bind the same receptor targeted by diabetes drugs like Ozempic?
If this target annotation is wrong, researchers could avoid wasting resources on a drug design based on a false connection. If it turns out to be real, it could point to a brain peptide with untapped metabolic effects.
Does the brain's own galanin system break down in people with long-term nerve pain?
If chronic pain patients lose their natural galanin brake, a galanin-based treatment could restore this missing signal and relieve pain through a completely different mechanism than opioids, potentially without addiction risk.
Could joining the active parts of two natural brain peptides create a more powerful anti-seizure candidate?
For patients with drug-resistant epilepsy, a dual-action peptide could in principle provide seizure control that neither component achieves alone, using the brain's own signaling molecules as a starting point.
Does the small structural difference between human and rat galanin change how the peptide behaves?
If confirmed, pain and epilepsy researchers could design modified galanin drugs that restore the missing chemical feature and test whether they outperform the natural human peptide.
Does the chemical difference at the tail of human galanin change how well it calms seizure activity in the brain?
If it holds, epilepsy researchers could design a galanin-based drug with the missing chemical group restored and test it for patients whose seizures resist current medications.
▸full evidence table1 metrics
| metric | value | tool |
|---|---|---|
| Ki | 545 nM | GPCRDB/ChEMBL |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.921 | global PDE — lower = better |
| disorder | 0.179 | fraction disordered |
| chain pair ipTM (A, B) | 0.465 | interface quality |
▸3-letter notation
▸recipeopenfold3-mlx 0.3.1
| parameter | value |
|---|---|
| model | openfold3-mlx 0.3.1 |
| weights | aedd8f3eb814e392… |
| hardware | apple_m4_base_16gb |
| mlx version | 0.31.1 |
| python | 3.14.3 |
| random seed | 42 |
| msa strategy | colabfold |
| diffusion samples | 1 |
| runtime | 237s |
| predicted by | mlx@peptide |
| predicted at | 2026-04-23 |
python3 openfold3/run_openfold.py predict --query_json {query.json} --runner_yaml examples/example_runner_yamls/mlx_runner.yml --output_dir {output_dir} --num_diffusion_samples 1 ▸citationbibtex
@peptide{pep10336,
sequence = {GWTLNSAGYLLGPHAVGNHRSFSDKNGLTS},
target = {galr1},
author = {peptidemodel},
year = {2026},
status = {bioassayed}
}