INS and nicotine dependence: KEGG analysis of miR-199a-5p target genes showed that a total of 7 signaling pathways (FC > 2, P < 0.05, Fig. 5C) were screened, such as GABAergic synapse, insulin signaling pathway, Lysosome, HIF-1 signaling pathway, retrograde endocannabinoid signaling, glycine, serine and threonine metabolism, nicotine addiction.