Therefore, experimental evidence from several recent studies supports the view that alterations in the endocrine system regulated by NK-1R and SP contribute to the development of pathologies such as depression, neural degeneration, alcohol addiction, pain, migraine, inflammatory bowel disease, pruritus, viral infection, bacterial infection, cancer, and emesis [27, 35, 61–65]. This evidence concerns the gene TACR1 and major depressive disorder.