BNC2 and depressive symptom measurement: In a previous study, mmu_circ_0001223 (derived from Bnc2 gene, also called circ‐Bnc2) was found to be significantly downregulated in a chronic unpredictable mild stress mice model, and its overexpression could promote the protein expression of CREB1 and BDNF to alleviate depression progression (Zhang et al., 2018).