Sex differences in cannabinoid addiction-like behaviors and exploratory miRNA findings in a WIN 55,212-2 self-administration mouse model

Cannabis is one of the most widely used psychoactive substances worldwide, and cannabis use disorder (CUD) is increasingly recognized as a major public health concern. Clinical evidence indicates that women may be particularly vulnerable to developing addiction, exhibiting a faster transition from initial drug use to loss of control and increased relapse vulnerability. However, females remain underrepresented in both preclinical and clinical research, limiting our understanding of the neurobiological mechanisms underlying this susceptibility. Here, we investigated sex differences in behavioral and epigenetic susceptibility to cannabinoid addiction using a mouse operant self-administration model with the synthetic cannabinoid agonist WIN 55,212-2. Females showed significantly greater persistence of responding during drug-free periods and more compulsive-like responding under punishment than males, whereas motivation, extinction, cue-induced drug seeking, impulsivity, reward sensitivity, drug intake, and the proportion of animals meeting the addiction-like phenotype did not differ significantly between sexes. Exploratory PCA identified a dominant behavioral dimension that differentiated addiction-like from non-addiction-like animals and revealed a significant sex × phenotype interaction, indicating that the relationship between this multidimensional behavioral profile and the addiction-like phenotype differed according to sex. A pooled differential-expression contrast comparing females meeting the addiction-like criteria with all other animals identified five candidate miRNAs (downregulated mmu-miR-669j, mmu-miR-7036b-5p, mmu-miR-878-3p, mmu-miR-7017-3p and upregulated mmu-miR-3092-5p). However, within-sex phenotype contrasts yielded no miRNAs significant after multiple-testing correction, and candidate miRNAs were not consistently associated with the individual criteria defining the phenotype. Enrichment analyses of predicted targets highlighted synaptic organization, axon guidance, neurotransmission, and structural plasticity pathways. In summary, our findings reveal sex differences in specific core addiction-like behaviors and identify candidate miRNAs and related biological pathways in the mPFC, providing a hypothesis-generating foundation for future studies designed to disentangle sex and phenotype effects and experimentally validate the predicted molecular targets.