Ghrelin, Alcohol Craving, and Addiction
Peptides & Alcohol Use
50% less drinking
Ghrelin knockout mice consumed approximately 50% less alcohol voluntarily than wild-type controls and showed reduced ethanol-conditioned place preference.
Bahi et al., Neuroscience Letters, 2013
Bahi et al., Neuroscience Letters, 2013
View as imageThe same 28-amino-acid peptide that makes you want food also makes you want alcohol. Ghrelin, produced primarily by the stomach during fasting, is best known as the "hunger hormone." It drives appetite by activating growth hormone secretagogue receptor 1A (GHS-R1A) in the hypothalamus. But ghrelin's reach extends far beyond meal initiation. It activates GHS-R1A on dopamine neurons in the ventral tegmental area (VTA), the brain's core reward circuit, amplifying the motivational salience of any rewarding stimulus, including alcohol.
This overlap between hunger and addiction is not a metaphor. It is a shared molecular mechanism operating through the same receptor, the same neurons, and the same neurotransmitter. Leggio (2010) identified the ghrelin system as a novel target for treating alcohol dependence, proposing that blocking GHS-R1A could reduce alcohol craving by interrupting the peptide signal that tells the brain to seek reward.[1] The subsequent decade of research has largely supported this hypothesis, culminating in the first randomized controlled trial of a ghrelin receptor blocker in people with alcohol use disorder (AUD). For a broader look at how peptides modulate dopamine-driven motivation, see our article on dopamine and peptide modulation.
Key Takeaways
- Ghrelin knockout mice consumed ~50% less alcohol voluntarily and showed reduced ethanol-conditioned place preference compared to wild-type controls (Bahi et al., 2013)
- Acylated ghrelin levels in early abstinent alcohol-dependent patients correlated positively with alcohol craving, with higher ghrelin predicting stronger urges to drink (Koopmann et al., 2012)
- A 2024 randomized, double-blind, placebo-controlled trial tested a GHS-R blocker (PF-5190457) in people with AUD, the first clinical trial directly targeting the ghrelin system for alcohol dependence (Faulkner et al., 2024)
- Ghrelin receptor antagonism reduced nicotine-induced dopamine release in the nucleus accumbens by blocking the same VTA mechanism that drives alcohol reward (Jerlhag et al., 2011)
- LEAP-2, a liver-derived endogenous ghrelin antagonist, represents a natural counter-regulatory system that may be pharmacologically exploitable for addiction treatment (Lu et al., 2021)
- Epigenetic changes in ghrelin (GHRL) and ghrelin receptor (GHSR) gene methylation differ between AUD patients and controls, suggesting alcohol exposure alters ghrelin system regulation (Ozkan-Kotiloglu et al., 2024)
How Ghrelin Drives Reward-Seeking
Ghrelin's connection to reward is not a side effect of its metabolic function. It is a core feature of the peptide's biology. Abizaid et al. (2006) demonstrated that ghrelin doubled the firing rate of dopamine neurons in the VTA and reorganized their synaptic inputs, shifting the balance toward more excitatory and less inhibitory tone.[2] This is not a subtle modulation. It is a reconfiguration of the brain's motivational circuitry.
Wei et al. (2015) showed that ghrelin signaling in the VTA mediates both reward-based feeding and fasting-induced hyperphagia on high-fat diets, establishing that ghrelin's reward effects are not limited to a single type of rewarding stimulus.[3] The VTA dopamine neurons that respond to ghrelin do not distinguish between food and drugs. They respond to any stimulus that the organism has learned to associate with reward. Ghrelin's role is to amplify the gain on this system: when ghrelin is high (during fasting, stress, or alcohol withdrawal), the brain's reward circuits become more responsive to all rewarding cues.
The mechanism involves two complementary pathways. First, ghrelin increases the excitability of VTA dopamine neurons by modulating ion channel activity and synaptic input balance, making them more likely to fire in response to any excitatory input. Second, ghrelin enhances the release of dopamine in the nucleus accumbens for a given level of VTA neuron firing, amplifying the downstream signal. The combined effect is a multiplicative increase in the dopamine response to rewards, which the brain interprets as heightened motivational salience. A glass of wine that produces a moderate dopamine signal under low-ghrelin conditions produces a substantially larger signal when ghrelin is elevated.
Wren et al. (2001) conducted one of the earliest human studies showing that ghrelin enhances appetite and increases food intake when administered to healthy volunteers.[4] This established ghrelin as a bona fide appetite-stimulating hormone in humans, not just rodents. The parallel with alcohol is direct: ghrelin does not create the desire for a specific reward. It creates a state of heightened motivation that makes any available reward more compelling.
The Ghrelin-Alcohol Link: Preclinical Evidence
Knockout Studies
Bahi et al. (2013) provided some of the strongest causal evidence by studying ghrelin knockout mice. Animals lacking the ghrelin gene consumed approximately 50% less alcohol voluntarily than wild-type controls.[5] They also showed reduced ethanol-induced conditioned place preference, a behavioral measure of how rewarding an animal finds a drug. Ghrelin-deficient mice were not incapable of consuming alcohol; they simply found it less motivating. This is consistent with ghrelin's role in "wanting" rather than "liking": the hedonic properties of alcohol may be intact, but the drive to seek and consume it is diminished.
The knockout data is complemented by administration studies. When exogenous ghrelin is injected directly into the VTA of rats, alcohol consumption increases dose-dependently. When it is injected into the nucleus accumbens, the effect is smaller, suggesting the VTA is the primary site where ghrelin amplifies alcohol reward. Peripheral ghrelin administration (mimicking the natural rise that occurs during fasting or stress) also increases alcohol-seeking behavior in animal models, though the effect is less pronounced than central administration because of the blood-brain barrier's partial restriction of ghrelin access to the CNS.
Receptor Blockade
Jerlhag et al. (2011) demonstrated that blocking GHS-R1A with a receptor antagonist reduced nicotine-induced locomotor stimulation and dopamine release in the nucleus accumbens.[6] While this study focused on nicotine, the mechanism is directly relevant to alcohol: GHS-R1A blockade reduces the dopamine response to drugs of abuse by interrupting ghrelin's amplification of VTA dopamine neuron firing.
Engel et al. (2015) extended this to opioid reward, showing that a GHS-R1A antagonist attenuated the rewarding properties of morphine and simultaneously increased endogenous opioid peptide levels in reward-related brain regions.[7] This finding suggests that ghrelin receptor blockade does not simply suppress reward. It shifts the balance between the ghrelin system and the endogenous opioid system, potentially compensating for the loss of ghrelin-mediated reward with enhanced opioid peptide signaling. For more on how opioid peptides interact with reward circuits, see our article on neuropeptides and alcohol dependence.
Human Clinical Evidence
Ghrelin and Craving
Koopmann et al. (2012) measured acylated ghrelin levels in early abstinent alcohol-dependent patients and found a positive correlation between ghrelin concentration and alcohol craving scores.[8] Patients with higher circulating ghrelin reported stronger urges to drink. This correlation held after controlling for confounders including body mass index and time since last drink. The finding is clinically significant because it identifies a measurable biomarker (plasma ghrelin) that tracks with the subjective experience of craving.
The relationship between ghrelin and alcohol is bidirectional and temporally dynamic. Alcohol consumption acutely suppresses ghrelin levels within 30-60 minutes of ingestion, similar to how a meal suppresses ghrelin. But alcohol withdrawal causes ghrelin to rebound above baseline, often exceeding pre-drinking levels. This rebound may contribute to the intense craving that characterizes early abstinence: the same peptide surge that makes fasting uncomfortable also amplifies the desire for alcohol during the withdrawal period.
The temporal pattern matters for treatment. During active drinking, ghrelin is suppressed and may not be driving consumption. During abstinence, especially the first 1-2 weeks, ghrelin levels are elevated and correlate with craving intensity. This suggests a therapeutic window: ghrelin receptor blockade may be most valuable during early abstinence when ghrelin rebound is at its peak, rather than as a maintenance medication for long-term sobriety. This contrasts with GLP-1 agonists, which appear to reduce drinking during both active consumption and abstinence phases.
Genetic and Epigenetic Evidence
Landgren et al. (2008) identified polymorphisms in the pro-ghrelin and GHS-R1A genes that were associated with heavy alcohol use and elevated body mass.[9] Specific haplotypes of the GHS-R1A gene were overrepresented in heavy drinkers compared to controls, suggesting genetic variation in ghrelin signaling influences susceptibility to AUD. The association with body mass is notable: it implies that ghrelin-related genetic variants simultaneously influence both appetite regulation and alcohol preference, providing molecular evidence for the shared biology of food and alcohol reward.
Ozkan-Kotiloglu et al. (2024) extended this to epigenetics, finding that methylation patterns of both the GHRL (ghrelin) and GHSR (ghrelin receptor) genes differed between AUD patients and controls.[10] This suggests that chronic alcohol exposure does not just interact with the ghrelin system through receptor activation. It remodels the regulation of ghrelin-related genes themselves, potentially creating long-lasting changes in ghrelin signaling that persist after alcohol cessation. These epigenetic modifications could explain why craving persists long after the acute pharmacological effects of alcohol have cleared.
The First Clinical Trial: PF-5190457
Faulkner et al. (2024) reported results from the first randomized, double-blind, placebo-controlled trial of a GHS-R blocker (PF-5190457) in people with alcohol use disorder.[11] This trial represented the culmination of over a decade of preclinical work suggesting that ghrelin receptor blockade could reduce alcohol consumption. PF-5190457 is a small molecule inverse agonist of GHS-R1A, meaning it does not simply block ghrelin from binding the receptor; it actively suppresses the receptor's constitutive (baseline) activity. GHS-R1A is unusual among G protein-coupled receptors in that it has high constitutive activity, signaling even in the absence of ghrelin. This constitutive activity may contribute to baseline reward-seeking behavior, and inverse agonists that suppress it could have effects beyond what a neutral antagonist would achieve. The study was designed as a proof-of-concept trial and measured alcohol craving, consumption, and related outcomes. While the full results require careful interpretation in the context of the specific compound's pharmacology and trial design, the trial itself is a milestone: it established that targeting the ghrelin system for AUD is clinically feasible and that GHS-R antagonists can be safely administered to patients with active alcohol use disorder. For more on how NPY intersects with alcohol seeking, see our article on neuropeptide Y and alcohol.
LEAP-2: The Body's Own Ghrelin Blocker
The discovery of liver-expressed antimicrobial peptide 2 (LEAP-2) as an endogenous ghrelin receptor antagonist reshaped the understanding of ghrelin regulation. Al-Massadi et al. (2018) described ghrelin and LEAP-2 as "rivals in energy metabolism," showing that LEAP-2 directly competes with ghrelin for GHS-R1A binding.[12]
Lu et al. (2021) reviewed LEAP-2's role as an emerging endogenous ghrelin receptor antagonist, noting that LEAP-2 levels rise after meals and fall during fasting, creating a mirror-image pattern to ghrelin.[13] When ghrelin is high (fasting), LEAP-2 is low, permitting ghrelin-driven appetite and reward-seeking. When LEAP-2 is high (fed state), ghrelin signaling is suppressed.
The implications for addiction are tantalizing but unproven. If LEAP-2 functions as a natural brake on ghrelin-driven reward-seeking, then patients with low LEAP-2 levels might be more vulnerable to ghrelin-amplified craving. Pharmacological LEAP-2 analogs or strategies to increase endogenous LEAP-2 production could theoretically reduce alcohol craving without the side effects associated with synthetic GHS-R1A antagonists. This remains speculative; no clinical trials of LEAP-2 for addiction exist. However, the discovery of an endogenous ghrelin counter-regulatory system opens a conceptually different therapeutic approach: rather than blocking ghrelin's receptor with a synthetic antagonist, enhancing the body's own ghrelin-suppressing mechanism could achieve similar effects with potentially better tolerability and fewer off-target effects.
Ghrelin Beyond Alcohol: A General Addiction Signal?
The ghrelin-reward connection is not specific to alcohol. Sustkova-Fiserova et al. (2022) reviewed ghrelin's role in nonalcohol drug addictions, documenting its involvement in the reward and reinforcement of nicotine, cocaine, amphetamine, and opioid use.[14] The common mechanism is ghrelin's action at GHS-R1A on VTA dopamine neurons: regardless of which substance triggers dopamine release, ghrelin amplifies the signal.
Gupta et al. (2022) reviewed the therapeutic potential of GHS-R1A antagonism specifically for alcohol dependence, concluding that the preclinical evidence is strong and consistent but that clinical translation has been slowed by the pharmacological challenges of developing orally bioavailable, brain-penetrant GHS-R1A antagonists with acceptable side effect profiles.[15]
Meyer et al. (2014) added a stress dimension, showing that a ghrelin-growth hormone axis drives stress-induced vulnerability to enhanced fear responses.[16] Since stress is a primary trigger for alcohol relapse, this connection provides another pathway through which ghrelin could drive drinking behavior: stress raises ghrelin, which amplifies both anxiety and reward-seeking, creating a combined push-pull toward alcohol consumption. The stress-ghrelin-alcohol axis may be particularly relevant in patients who drink primarily to cope with anxiety or negative affect, a subtype of AUD that is associated with worse treatment outcomes using existing pharmacotherapies. If ghrelin mediates the stress-to-craving pathway, targeting ghrelin in stress-driven drinkers could address the specific biology driving their alcohol use in a way that current treatments do not. See our article on oxytocin for alcohol use disorder for how another peptide system approaches this problem.
The GLP-1 Connection
While this article focuses on ghrelin, the convergent evidence that GLP-1 receptor agonists reduce alcohol consumption deserves mention because GLP-1 and ghrelin are functional antagonists. Chuong et al. (2023) showed that the GLP-1 analogue semaglutide reduced alcohol drinking in rodent models and modulated central GABA neurotransmission in reward-processing brain regions.[17] The mechanism may involve suppression of ghrelin-mediated VTA dopamine activation: GLP-1 receptor activation in the VTA directly opposes ghrelin's excitatory effects on dopamine neurons.
The clinical observation that patients on semaglutide for diabetes or obesity spontaneously report reduced interest in alcohol supports this mechanistic connection. If ghrelin amplifies reward-seeking and GLP-1 suppresses it, then the ratio of these two peptide signals may be a more important determinant of craving than the absolute level of either one.
This framework suggests a multi-target approach to alcohol craving: combining ghrelin receptor blockade (to reduce the "push" toward reward-seeking) with GLP-1 receptor activation (to increase the "brake" on reward circuits). No trial has tested this combination directly, but the biological rationale is stronger than for either intervention alone. The challenge is that ghrelin receptor antagonists are still in early clinical development, while GLP-1 agonists are already widely prescribed for diabetes and obesity, creating an asymmetry in clinical readiness.
What Remains Unknown
The ghrelin-alcohol field has generated compelling preclinical data but limited clinical evidence. Only one randomized trial of a ghrelin receptor antagonist for AUD has been completed, and the results require replication with larger samples and longer follow-up. The optimal pharmacological approach (GHS-R1A inverse agonist, neutral antagonist, or biased ligand) has not been determined.
Whether ghrelin system interventions would work for all AUD patients or only a subpopulation is unknown. Patients with specific GHSR genotypes or elevated baseline ghrelin levels might respond preferentially. The genetic and epigenetic data from Landgren et al. (2008) and Ozkan-Kotiloglu et al. (2024) suggest biological heterogeneity that could guide patient selection, but no biomarker-stratified trials have been conducted.
The interaction between ghrelin and other peptide systems involved in alcohol dependence (NPY, CRF, dynorphin, oxytocin) is poorly characterized. Alcohol dependence involves dysregulation of multiple neuropeptide systems simultaneously. Targeting ghrelin alone may be insufficient if compensatory changes in other systems maintain craving through alternative pathways.
The LEAP-2 pathway remains entirely unexplored in the context of addiction. If LEAP-2 is the body's natural ghrelin brake, understanding how alcohol exposure affects LEAP-2 levels and whether LEAP-2 supplementation could reduce craving would be valuable. Since LEAP-2 is produced by the liver, and chronic alcohol use damages the liver, it is plausible that alcohol-related liver injury reduces LEAP-2 production, further disinhibiting ghrelin signaling and creating a vicious cycle: alcohol damages the liver, which produces less LEAP-2, which allows more ghrelin-driven craving, which drives more alcohol consumption.
The sex differences in ghrelin-alcohol interactions are understudied. Baseline ghrelin levels differ between men and women, ghrelin's response to alcohol varies by sex, and the prevalence and presentation of AUD differ between sexes. Whether ghrelin receptor blockade would be equally effective in men and women has not been tested. The limited preclinical data suggests sex-dependent effects, but no clinical trial has stratified results by sex.
The relationship between ghrelin and other approved AUD medications (naltrexone, acamprosate, disulfiram) is unknown. If ghrelin receptor blockade reduces craving through a mechanism distinct from opioid receptor blockade (naltrexone) or glutamate modulation (acamprosate), combination therapy could provide additive benefits. Conversely, if the mechanisms overlap, adding a ghrelin blocker to existing treatment might offer limited additional benefit.
The Bottom Line
Ghrelin drives alcohol craving through the same GHS-R1A/VTA dopamine mechanism that drives food-seeking behavior. Preclinical evidence is strong: ghrelin knockout mice drink ~50% less, ghrelin receptor antagonists reduce drug reward, and ghrelin levels correlate with human craving scores. The first clinical trial of a ghrelin receptor blocker for AUD has been completed. LEAP-2, an endogenous ghrelin antagonist, represents a novel angle. Genetic and epigenetic studies show the ghrelin system is remodeled by chronic alcohol exposure. The field is at the translational stage, with robust animal data awaiting broader clinical validation.