Rapid Changes in Cholinergic Signaling, Myelination, and Thyroid Signaling Pathway Gene Expression in Amygdala Subnuclei in Response to Social Status Maintenance and Reorganization.

Male CD-1 mice form linear social hierarchies and can rapidly reform them following social reorganization. Through tag-based sequencing in the medial amygdala (MeA), we identified several genes regulating cholinergic signaling, myelination, and thyroid signaling that rapidly shift expression 70 min after animals change social status. Here, we further characterize the expression patterns of individual genes within these pathways in both stable and reorganized hierarchies. We find that genes related to cholinergic signaling show higher expression in the MeA of dominant males in stable hierarchies as well as when reestablishing dominance in reorganized hierarchies. Dominant males also show higher levels of myelination-related genes than socially descending males when reestablishing their social status during social reorganization but less so in stable groups. Conversely, thyroid signaling genes show higher expression in the MeA in subordinate males and previously dominant males who are socially descending. Using RNAscope, we were able to demonstrate broadly similar patterns of gene expression immediately following social reorganization across the MeA, basolateral, and central amygdala for seven genes of interest (chat, slc5a7, ache, mbp, mog, crym, and mybpc1). High levels of coexpression of cholinergic signaling and myelination gene expression in dominant males suggest that these processes work together to promote resilience to the social challenge and promote dominance. In summary, we demonstrate that rapid changes in amygdala gene expression in each pathway are associated with the formation and maintenance of dominance and subordinate social status in stable and reorganized environments.