Galanin

GAL; galanin-like peptide (GALP) and alarin are separate products of related genes; receptors GalR1, GalR2, GalR3

Cognitive & neuro

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Summary

Class: Naturally occurring neuropeptide — 29 amino acids in most species, 30 in humans, with the human form lacking the C-terminal amide found in rat galanin
Mechanism: Acts at three G-protein-coupled receptors (GalR1–3), mostly inhibitory: it quietens neuronal firing, suppresses insulin release, dampens pain signalling and limits seizure spread
Routes studied: Intravenous infusion in human physiology studies; intracerebroventricular and intrathecal in animals. No practical systemic route for central effects — galanin does not cross the blood–brain barrier well
Half-life: Short; minutes in plasma
Storage: Research peptide; lyophilised, cold storage. Not a consumer product
Regulatory status: Not approved anywhere. No galanin-receptor drug has reached the market

Doses are as reported in studies or by the community — never recommendations.

1What it is

Galanin is one of your own neuropeptides, isolated in 1983 and named for its first and last amino acids — glycine at one end, alanine at the other. It is widely distributed: in the hypothalamus, the locus coeruleus, the spinal cord, the gut, the pancreas and the adrenal medulla.

Its defining feature is that it is a brake. Where galanin is released it generally reduces activity — neuronal firing, insulin secretion, pain transmission, seizure propagation. It is also strongly upregulated after nerve injury and in the hippocampus after seizures, which looks like an endogenous protective response, and that observation is the core of the therapeutic interest.

The practical obstacle is delivery. The effects people want are central, and a 30-amino-acid peptide given into a vein does not reach the brain in useful amounts. So the field has worked on small-molecule and peptidomimetic GalR rather than on galanin itself. Community use: essentially none documented, and the blood–brain barrier is the reason informal use would be pointless.

2How it's thought to work

GalR1 and GalR3. couple through Gi/Go: they lower cAMP, open potassium channels and hyperpolarise neurons — straightforwardly inhibitory.

GalR2. couples through Gq and can be excitatory or trophic, which is why galanin's effects sometimes look contradictory: the net result depends on which receptor dominates in a given tissue.

Anticonvulsant action. in the hippocampus is attributed mainly to GalR1 and GalR2 suppressing glutamate release from excitatory terminals.

Pancreas. inhibits insulin secretion from beta cells, acting as a sympathetic co-transmitter.

Pituitary. paradoxically stimulates growth hormone release in humans, which was the subject of several early human infusion studies.

Nerve injury and regeneration. galanin expression rises sharply in injured sensory neurons and supports axonal regrowth in animal models.

Feeding. stimulates intake, particularly of fat, when given centrally in rodents.

Galanin at its Gi-coupled receptors: potassium leaves the cell and calcium entry is held back, so the neuron fires less. It is an inhibitory brake rather than a driver, which is why its effects read as quietening across several systems.Schematic — not to scale

3What the research shows

Growth hormone release in humans

Intravenous galanin reliably stimulates GH secretion in healthy volunteers, and amplifies GHRH-induced GH release — one of the better-replicated human findings about this peptide (Bauer 1986, Lancet; Davis and colleagues; Giustina and colleagues, 1990s). These were endocrine physiology experiments, not treatments. [2]

Insulin suppression in humans

Human infusion studies report inhibition of insulin secretion and effects on glucose tolerance, consistent with the pancreatic physiology. Small and short.

Epilepsy

This is the strongest preclinical case. Galanin and GalR suppress seizures across multiple rodent models, galanin knockout animals are more seizure-prone, and gene-therapy and cell-delivery approaches for focal epilepsy using galanin have shown benefit in animals. No human trial.

Pain

Spinal galanin has complex, dose- and receptor-dependent effects on nociception, generally inhibitory at higher doses via GalR1. Intrathecal animal work only.

Depression and anxiety

Galanin interacts tightly with the noradrenergic locus coeruleus and the serotonergic system. Animal work points to GalR3 antagonism as antidepressant-like and GalR2 agonism as anxiolytic-like. Small-molecule GalR3 antagonists were pursued by industry; none reached approval, and published human efficacy data are lacking †.

Feeding, obesity and alcohol intake

Rodent studies tie central galanin to fat preference and to alcohol consumption. Attractive mechanistically, untranslated.

Neuroprotection and nerve regeneration

Animal models of nerve injury and neurodegeneration report protective effects. Galanin is also found in high concentrations in some Alzheimer's brain tissue, with debate over whether that is compensatory or harmful. The literature on galanin is broad and mechanistically rich but thin in humans: the human evidence is essentially a handful of endocrine infusion studies from three decades ago.

4Reported side effects and interactions

Literature-reported

Short human infusions were tolerated; the documented effects were endocrine (GH rise, insulin suppression) rather than symptomatic. No modern human safety dataset exists.

Community-reported

None. Not in self-directed use.

Theoretical. The obvious hazards from mechanism are impaired insulin secretion with sustained exposure, and unpredictable central effects if a brain-penetrant were used — galanin's receptor subtypes pull in different directions, and a non-selective agonist could plausibly worsen the thing it was meant to treat.

Interactions. Conceptual interaction with anything affecting insulin secretion or the GH axis; with noradrenergic and serotonergic drugs on the central side. No formal studies.

Markers researchers commonly monitor

Based on the human endocrine studies and on mechanism, not on any clinical protocol:

Marker	Why it's watched
Growth hormone and IGF-1	the one reproducible human pharmacodynamic effect is GH release.
Fasting glucose, insulin and C-peptide	galanin suppresses insulin secretion; this is the clearest metabolic safety concern.
Seizure frequency, where relevant	the epilepsy hypothesis is the main therapeutic rationale, but it is animal-level.
Mood and anxiety rating scales	used in the preclinical-to-clinical translation discussion; no validated human galanin data.
CBC and CMP	general baseline for any investigational peptide.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Not applicable as a consumer practice. Research-grade galanin is prepared for infusion in laboratory and clinical-physiology settings. Because the peptide does not meaningfully cross the blood–brain barrier, peripheral administration cannot deliver the central effects described in the animal literature — a point worth stating plainly, since it is the main thing that would mislead someone reading the preclinical papers. No calculator preset applies.

6Commonly studied alongside

Neuropeptide Y (#157 — the other major inhibitory/orexigenic neuropeptide, often studied together in feeding and in epilepsy gene therapy), somatostatin (#160 — another inhibitory peptide co-expressed in overlapping circuits), GHRH analogues in the endocrine studies.

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	Not FDA-approved; research use only
European Union	Not authorised
United Kingdom	Not licensed
Australia	Not approved
South Africa	Not registered
Sport	Not specifically listed by WADA. Note that galanin stimulates GH release in humans, so a galanin-receptor agonist used for that purpose would arguably fall under S2 (peptide hormones and growth factors) as well as S0. Check the current list

8Open questions

Can a brain-penetrant, receptor-selective galanin be made, and would GalR1/GalR2 agonism be anticonvulsant in humans?
Is galanin's upregulation after injury and seizure protective, or a marker of damage?
Does the GalR3-antagonist antidepressant hypothesis survive a proper human trial?
What does galanin's effect on insulin secretion mean for metabolic health in people with naturally high galanin signalling?

9References

1Tatemoto K, Rökaeus Å, Jörnvall H, McDonald TJ, Mutt V (1983). Galanin — a novel biologically active peptide from porcine intestine. FEBS Lett. PubMed · DOI
2Bauer FE et al. (1986). Effect of galanin on human gastrointestinal and pancreatic function. Lancet [verify exact title]. PubMed
3Lang R, Gundlach AL, Kofler B (2007). The galanin peptide family: receptor pharmacology, pleiotropic biological actions, and implications in health and disease. Pharmacol Ther. PubMed · DOI
4Mazarati AM et al. (1998). Galanin modulation of seizures and seizure modulation of hippocampal galanin in animal models of status epilepticus. J Neurosci. PubMed · DOI
5Holmes A et al. (2003). Galanin: a novel therapeutic target for depression, anxiety disorders and drug addiction? CNS Neurol Disord Drug Targets [verify journal]. PubMed
6Webling KEB, Runesson J, Bartfai T, Langel Ü (2012). Galanin receptors and ligands. Front Endocrinol. PubMed · DOI

References are being resolved to PubMed/DOI identifiers; links search PubMed for the citation until then.

† Being confirmed by our reviewers against current sources.

10Community

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11Page history

30 Oct 2026Profile published — awaiting medical review

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