Alcohol dependence (AD) afflicts ~10% of the US population and causes serious morbidity and mortality. Ghrelin is a 28-aminoacid peptide that stimulates appetite and food intake. It is an endogenous ligand for the growth hormone secretagogue receptor (GHSR1a). Preclinical studies suggest that ghrelin also modulates alcohol reward processing. Central ghrelin administration to mice significantly increased alcohol intake, and this increase was even more robust when ghrelin was administered bilaterally into specific brain reward nodes, e.g. the ventral tegmental area. Similarly, in alcoholic individuals, higher plasma ghrelin concentrations are associated with higher alcohol craving and consumption. Collectively, these studies provide evidence that manipulations of the ghrelin system affect alcohol craving and consumption. Therefore, an orally bioavailable, ghrelin receptor antagonist, that can pass through the blood brain barrier holds particular promise as an AD treatment. This proposal will allow us to generate preliminary evidence on the safety and efficacy of such pharmacological agent via three projects, i.e.: (P1) a set of experiments testing the effect of this drug in well-validated animal models of alcohol-seeking behavior; (P2) a drug/alcohol interaction study to establish safety in humans (Phase 1b); and (P3) a human laboratory study to assess the efficacy of this drug on alcohol-seeking behavior via a set of well- validated procedures (alcohol cue-reactivity, alcohol self-administration, intravenous alcohol progressive ratio infusion) as well as characterization of the drug effect on reward processing neurocircuitry in the context of alcohol using fMRI (Phase 2a). These projects will be conducted in the NIAAA Intramural Program (PI: Leggio). Furthermore, all three projects will include pharmacokinetics (PK) and pharmacodynamic (PD) investigations conducted at University of Rhode Island (URI; PI: Akhlaghi). The PK/PD component will include (i) measuring total, unbound or tissue concentrations of the drug using liquid chromatography tandem mass spectrometry (LC- MS/MS) and evaluation of biomarkers of effect and (ii) estimation of PK and PD parameters in both animal and human studies by the use of conventional and semimechanistic modeling approaches to assist in identifying an optimal dosing regimen of the drug in AD. In summary, this research will investigate the tolerability, efficacy and mechanism of this novel pharmacological approach for AD thus leading to the potential identification of a new treatment for AD.
Alcohol dependence (AD) afflicts ~10% of the US population, therefore discovering new, more effective treatments for AD is essential. Antagonism of the ghrelin receptor represents a novel and promising pharmacological approach to treat AD; a better characterization of this approach may lead to a more effective pharmacotherapy for AD. This project is highly significant as it has the potential to identify a new more effective medication for AD and possibly other addictions (e.g. smoking).
