LEP and major depressive disorder: The CRF, which can be divided into “inflammation-driven” (high IL-6/miR-223), “leptin-related” (high leptin/miR-34a) and “depression-related type”, in which miR-223 exacerbates mitochondrial dysfunction by inhibiting PGC-1 α (Schmidt et al., 2024), illustrates the complementary mechanism of mitochondria inhibition of mitochondrial biosynthesis.