Investigating Circadian Dynamics and Dopaminergic Control of Neuronal Cilia in the Basolateral Amygdala

Abstract

Emotional responses such as fear and anxiety are regulated by intricate neural circuits that are modulated by various neuromodulators, including dopamine. Dopamine signaling in brain regions such as the basolateral amygdala (BLA) for emotional responses, may involve primary cilia and may be regulated by circadian rhythms. We investigated how primary cilia in BLA neurons function as signaling compartments for dopaminergic signaling and how cilia morphology changes in response to circadian time and activity of dopamine receptors. Using immunofluorescence imaging and a geometry-driven skeleton merging pipeline in anterior and posterior regions of the BLA, we found that cilia are longer and more numerous in the light phase, especially in posterior BLA, while vesicles are more prominent in the dark phase. We also found that activating D1R receptors in posterior BLA decreases cilia length, while inhibiting D1R receptors increases cilia length. However, In anterior BLA, D1-receptor activity does not affect cilia length. To assess the functional significance of ciliary signaling, we used CRISPR to knock out BBS4 in Drd1-expressing BLA neurons. We found that this disrupted ciliary signaling and altered exploration patterns in the EZM, although levels of anxiety were not significantly different, probably because of the small sample size. This study demonstrates that primary cilia in BLA neurons are subject to regulation by circadian and dopaminergic signaling and that ciliary compartmentalization may fine-tune emotional behaviors.