INS and nicotine dependence: In addition, the differential metabolites in the spermatozoa of the two pig breeds were mainly involved in the following metabolic pathways: glycerophospholipid metabolism, cholinergic synapse, bile secretion, ABC transporters, glycine, serine, and threonine metabolism, actin cytoskeleton regulation, nicotine addiction necroptosis, synaptic vesicle cycle, insulin secretion, gastric acid secretion, sphingolipid signaling pathway, and pancreatic secretion (Figure 5C).