¹Linköping University, Department of Biomedical and Clinical Sciences, Linkoping, Sweden, ²University of Texas at Austin, Departments of Neuroscience and Neurology, Austin, United States

Background: Alcohol use disorder (AUD) is a major public health challenge, contributing to an estimated 2.6 million deaths worldwide in 2019 and accounting for 4.7% of all deaths. A defining feature of AUD is the persistence of alcohol consumption despite negative consequences, commonly referred to as compulsive alcohol use. This behavior is strongly associated with the transition from controlled alcohol intake to addiction and distinguishes individuals who develop problematic drinking from those who maintain controlled consumption. In rodents, compulsive alcohol use can be modeled using a punishment-resistant self-administration paradigm, in which alcohol-seeking behavior is paired with mild footshock punishment. Similar to humans, most animals reduce alcohol seeking when punishment is introduced, whereas a subset continues responding despite adverse consequences.

Aims & Objectives: The aim of this study was to identify the neural and molecular mechanisms underlying individual vulnerability to compulsive alcohol drinking. Specifically, we sought to characterize cell-type-specific transcriptional changes associated with punishment-resistant alcohol self-administration and to identify potential therapeutic targets within relevant neuronal populations of the central nucleus of the amygdala (CeA).

Method: snRNA sequencing was performed in male rats displaying individual differences in punishment-resistant alcohol self-administration (n=12/groups). Transcriptomic alterations were examined across distinct CeA neuronal populations. High dimensional Weighted Gene Co-expression Network Analysis (hdWGCNA) was conducted to identify upstream regulatory pathways associated with compulsive drinking. To evaluate the functional role of identified targets, selective FgfR1 knockdown was performed in PKCδ+ neurons using transgenic Cre rat line that specifically expressed Cre in PKCδ+ cells. The effects on alcohol-seeking behavior were then assessed using punished alcohol self-administration. In parallel, the FGFR1 antagonist PD173074 was administered systemically to determine whether pharmacological inhibition of FGFR1 could reproduce the behavioral effects of genetic manipulation.

Results: Transcriptomic changes associated with compulsive-like alcohol self-administration were detected in a limited number of CeA neuronal populations, including PKCδ+ neurons. Network analysis identified fibroblast growth factor receptor 1 (FGFR1) as a druggable upstream regulator of a PKCδ+-specific gene module linked to compulsive drinking behavior. Selective knockdown of FgfR1 in PKCδ+ neurons normalized elevated PKCδ expression and significantly reduced punishment-resistant alcohol self-administration. Consistent with these findings, systemic administration of the FGFR1 antagonist PD173074 reduced compulsive alcohol seeking in a dose-dependent manner.

Discussion & Conclusions: These findings identify a CeA PKCδ–FGFR1 signaling pathway that contributes to the development and maintenance of compulsive-like alcohol use. The results provide mechanistic insight into individual vulnerability to punishment-resistant alcohol drinking and demonstrate that targeting FGFR1 can reduce compulsive alcohol-seeking behavior. Collectively, the study highlights FGFR1 as a promising therapeutic target for the treatment of AUD and supports further investigation of FGFR1-directed interventions in addiction.