Galanin
Galanin, the 30 residue human GAL gene product
Written by Aaron CuhaReviewed Sep 2026
Also known as: GAL, Galanin (1-30)
Infused into healthy human volunteers since 1986, and every one of those studies measured a hormone or a blood pressure. It is a potent growth hormone secretagogue in humans, plasma half-life about 3.7 minutes, and one controlled infusion raised supine heart rate from 70 to 99 beats per minute. Nobody has ever run a cognitive endpoint with it.
Overview
Galanin is the human compound in this batch with the longest record of actually being given to people, and the widest gap between that record and its nootropic reputation.
It is a 30 residue neuropeptide, annotated in UniProt P22466 at residues 33 to 62. Human galanin differs from the porcine peptide used in the earliest studies, which matters when reading the older literature.
Human infusion studies begin in 1986 with a Lancet report in healthy volunteers and continue through the mid-1990s. They are consistent and they are endocrine. Galanin is a potent growth hormone secretagogue: in one study, plasma growth hormone rose from a baseline of 2.8 mU/L to a mean peak of 48.5 mU/L during high-dose infusion. Human galanin infused during a hyperglycaemic clamp raised growth hormone eightfold and had no effect on insulin, C-peptide, glucagon or glucose metabolism at the concentrations achieved. High-dose porcine galanin had no effect on plasma glucose or serum insulin during an intravenous glucose tolerance test, which led those authors to warn explicitly against extrapolating a physiological role for galanin in humans from animal results.
One of these studies is worth knowing about before considering this compound. A 60-minute infusion of human galanin in eight healthy men lowered supine plasma noradrenaline, blunted the noradrenaline response to standing, and increased supine heart rate from 70 to 99 beats per minute, while blunting the blood pressure response to standing. That is a substantial autonomic effect in healthy young men, measured, published, and almost never mentioned where galanin is sold.
The animal literature that gives galanin its neurological reputation, work on addiction, feeding, sleep and inflammation, is animal literature. The route used in that work is intracerebroventricular or local. There is no peripheral route shown to deliver galanin to a central target.
Mechanism of action
Demonstrated peripherally in humans, proposed centrally. Galanin acts at three G protein-coupled receptors, GALR1, GALR2 and GALR3. In humans, intravenous infusion demonstrably stimulates growth hormone secretion, potentiates the growth hormone response to growth hormone-releasing hormone, and modulates sympathetic outflow, lowering plasma noradrenaline while raising heart rate. The central roles in addiction, feeding and mood that drive its reputation are demonstrated in rodents by central administration, and there is no evidence that a peripheral dose reaches those central receptors.
Human evidence
Substantial and controlled, dating from 1986, and entirely endocrine and cardiovascular. Growth hormone, insulin, noradrenaline, heart rate, blood pressure. Not one study measured cognition, mood, addiction or appetite behaviour.
- Galanin is a potent growth hormone secretagogue in humans: plasma growth hormone rose from 2.8 to a mean peak of 48.5 mU/L during high-dose infusion in healthy volunteers (PMID 2425204), and human galanin raised growth hormone eightfold during a hyperglycaemic clamp (PMID 7689499).
- Plasma half-life 3.7 plus or minus 0.4 minutes for human galanin, measured during infusion (PMID 7689499).
- No effect on insulin, C-peptide, glucagon or glucose metabolism in humans at the concentrations achieved, despite clear inhibitory effects on insulin release in dogs and rodents (PMID 7689499, PMID 2475378).
- A 60-minute infusion in eight healthy men raised supine heart rate from 70 to 99 beats per minute, lowered supine plasma noradrenaline from 0.84 to 0.33 nmol/L, and blunted the blood pressure response to standing (PMID 7539818).
- Further human studies measured the growth hormone response to growth hormone-releasing hormone with and without galanin, prolactin, antidiuretic hormone, gonadotropins and cortisol, and postprandial gastrointestinal motility.
- No trial of galanin has used a cognitive endpoint, a mood endpoint or an addiction endpoint in humans.
What this does not tell you: These are acute single-infusion physiology experiments in small groups of healthy volunteers, typically four to eight people, with a peptide cleared in under four minutes. They establish what happens to hormones and haemodynamics during an hour of intravenous exposure. They establish nothing about repeated dosing, nothing about a central effect, and nothing about any behavioural outcome. The earliest studies used porcine galanin, which differs from the human peptide, so results are not directly interchangeable across the older literature.
Reading the research record
A published research review on this project previously recorded that galanin has no human interventional data. That was wrong, and the correction is worth stating plainly: galanin has been infused into human volunteers in controlled studies since 1986, and there are dozens of such reports through the mid-1990s. Anyone searching only recent literature or only for galanin plus a behavioural term will miss them.
What the correction changes is smaller than it sounds. The human data are real and they are all endocrine and cardiovascular. Galanin in a human is a growth hormone secretagogue with autonomic effects and no measurable effect on insulin or glucose, and that is the complete picture the human record provides.
The reputation is built elsewhere. Galanin's standing as a neuropeptide of interest comes from rodent work on addiction, feeding, sleep and inflammation, delivered intracerebroventricularly or locally. The gap between that route and anything a person could take is the whole problem, and one of the human studies names it directly: after finding that galanin did not affect insulin in humans the way it does in dogs and rodents, those authors concluded that caution should be exercised in extrapolating a physiological role for galanin in humans from animal results. That sentence was published in 1989 and it is still the correct summary.
The heart rate finding deserves more attention than it gets. A rise from 70 to 99 beats per minute at rest, in healthy young men, during a one-hour infusion, is not a subtle signal.
A cognitive endpoint is a measured one: a validated test of working memory, processing speed, attention, executive function or episodic recall, administered before and after, against a control group who did not know which arm they were in. None of the compounds in this batch has ever been tested that way. Rating scales of fatigue, global clinical impression, anxiety or hyperphagia are not cognitive endpoints, and neither is a hormone level. This matters because the marketing for several of these compounds describes focus, clarity and mental energy, and the underlying studies measured none of those things.
The evidence, charted
Fig. 1 · evidence composition
4of 6 citations (67%) are in people
Counted from the citation list on this page. The Human count is the same number shown in the badge at the top. Both understate any literature larger than the sources we cite.
Fig. 2 · evidence over time
Evidence spans 6 distinct years, 1986 to 2020, counted from the citation list on this page. The newest citation on file is from 2020, more than five years ago; the published record may have gone quiet.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Key studies & citations
- Human1986
Growth hormone release in man induced by galanin, a new hypothalamic peptide
The first human study. Galanin infused for 60 minutes into healthy volunteers at 7.8 pmol/kg per minute (n=4) or 33.2 pmol/kg per minute (n=6). Plasma growth hormone rose from 2.8 to a mean peak of 48.5 mU/L at the high dose and from 2.5 to 23.5 mU/L at the low dose; prolactin rose from 176 to 274 mU/L. No change in cortisol, TSH, FSH or LH. No change in heart rate or blood pressure at these doses; the only symptoms were a transitory bitter taste and slight hypersalivation. Galanin reduced glucose clearance after an intravenous glucose bolus without significantly affecting plasma insulin.
The Lancet - Human1993
On the effects of human galanin in man
Human galanin, not porcine, infused at 74 pmol/kg per minute for 60 minutes into six healthy volunteers during a hyperglycaemic clamp. Galanin concentrations plateaued around 1500 pmol/L against pre-infusion levels of 20 to 30 pmol/L. Growth hormone rose eightfold. Insulin, C-peptide, glucagon and glucose curves were indistinguishable from control. Galanin was eliminated from plasma with a half-life of 3.7 plus or minus 0.4 minutes. The authors conclude that human galanin powerfully stimulates growth hormone secretion in man but has no effect on pancreatic endocrine secretion or glucose metabolism at these concentrations.
Diabetologia - Human1995
Human galanin reduces plasma norepinephrine levels in man
The safety-relevant human study, in eight healthy male volunteers given a 60-minute infusion of human galanin at 80 pmol/kg per minute or saline. Galanin lowered supine plasma noradrenaline from 0.84 to 0.33 nmol/L and blunted the noradrenaline response to standing from 1.68 to 0.44 nmol/L, while enhancing the adrenaline response to standing. It raised supine heart rate from 70 to 99 beats per minute and the standing heart rate from 82 to 107, and blunted the systolic and diastolic blood pressure responses to standing. A substantial autonomic effect in healthy young men.
The Journal of Clinical Endocrinology and Metabolism - Human1989
High-dose porcine galanin infusion and effect on intravenous glucose tolerance in humans
Seven healthy male volunteers given an intravenous glucose tolerance test alone and with porcine galanin at 80 and 160 pmol/kg per minute. Galanin inhibits glucose-stimulated insulin release in dogs and rodents; in humans it had no effect on plasma glucose or serum insulin, though growth hormone still rose. The authors' explicit conclusion is that caution should be exercised in extrapolating a physiological role for galanin in humans from animal results, which is the central lesson of this entry.
Diabetes - Review2020
Neuropeptide modulation of addiction: Focus on galanin
The review behind galanin's reputation in addiction and reward. It reviews animal and cell work. No human interventional study of galanin for addiction, mood or cognition exists to review.
Neuroscience and Biobehavioral Reviews - Animal2018
Galanin Administration Partially Restores Erectile Function After Cavernous Nerve Injury and Mediates Endogenous Nitrergic Nerve Outgrowth In Vitro
Rats, with an in vitro component. Galanin administration partially restored erectile function after cavernous nerve injury and mediated nitrergic nerve outgrowth in culture. Included because this rat result circulates in consumer settings without its species attached.
The Journal of Sexual Medicine
Frequently asked questions
Has galanin ever been given to humans?
Yes, many times, starting with a Lancet report in 1986. Healthy volunteers have received intravenous galanin in controlled studies through the 1990s. Every one of those studies measured hormones or cardiovascular variables. None measured cognition, mood or appetite behaviour.
What does galanin actually do in a person?
It raises growth hormone, powerfully and reproducibly. In one study growth hormone went from 2.8 to a peak of 48.5 mU/L; in another it rose eightfold. It does not measurably affect insulin, C-peptide, glucagon or glucose in humans, despite doing so in dogs and rodents. And it has a clear autonomic effect: supine heart rate rose from 70 to 99 beats per minute during a one-hour infusion in healthy men.
Does galanin help with addiction or cravings?
That idea comes from rodent work, delivered directly into the brain. No human study has ever tested galanin for addiction, craving, mood or any behavioural outcome. Galanin given peripherally has no demonstrated route to the central receptors that hypothesis depends on.
Is galanin safe?
The acute human safety record is thin but not empty. Subjects in the earliest studies reported a transitory bitter taste and slight hypersalivation and showed no change in heart rate or blood pressure at those doses. At a higher dose in a later study, supine heart rate rose from 70 to 99 beats per minute and the blood pressure response to standing was blunted. There is no repeated-dose human safety data at all, and the peptide clears from plasma in under four minutes, so nothing is known about what sustained exposure would do.
How long does galanin last?
About 3.7 minutes in plasma, measured directly in healthy volunteers during intravenous infusion of human galanin. That is the measured elimination half-life, not an estimate.