CB1 receptor signaling at the cingulate-striatal circuit is anxiogenic

Cannabinoids, such as Δ⁹-tetrahydrocannabinol (THC), produce anxiety at high doses, yet the underlying neural mechanisms remain poorly understood. The anterior cingulate cortex (ACC) sends dense monosynaptic projections to the dorsomedial striatum (DMS). Optogenetic excitation of the ACC → DMS pathway promotes anxiolytic-like behavior, suggesting that its suppression could induce anxiogenic states. We hypothesized that CB1 receptor-mediated suppression of this circuit contributes to cannabinoid-induced anxiogenic effects. We found that endocannabinoid (eCB) system components are expressed in ACC → DMS neurons and that cannabinoids depress excitatory transmission in this circuit in mice. Additionally, in vivo fiber photometry revealed that anxiogenic and aversive stimuli trigger eCB release from the DMS, which activates CB1 receptors on ACC axon terminals. Notably, pathway-specific deletion of CB1 receptors in the ACC → DMS circuit reduced both innate anxiety-like behaviors and conditioned place aversion to THC in mice. Collectively, these findings identify a circuit-level mechanism whereby cannabinoid signaling promotes anxiety and aversion.