And the top enriched metabolic pathways in LC–MS platform were: Glycerophospholipid metabolism, Choline metabolism in cancer, Cholinergic synapse, Regulation of actin cytoskeleton, Biosynthesis of unsaturated fatty acids, Nicotine addiction, Synaptic vesicle cycle, Insulin secretion, Gastric acid secretion, Pancreatic secretion, Salivary secretion (p < 0.05; Figure 6B). Here, INS is linked to nicotine dependence.