HTR1A and major depressive disorder: In the context of antidepressant action, CBD reverses the upregulation of miR-16 and miR-135 in the PFC of CUMS-induced models, thereby alleviating depression-like behaviors through epigenetic normalization; second, it activates 5-HT1A receptors to counteract CUMS-induced transcriptional repression of the htr1a gene, ultimately enhancing serotonergic system function (Bright and Akirav, 2023).