Finally, all these targets—Bdnf, NF-kB, CREB and Sort1—were critical regulators of the neurotrophin pathway, and various aspects of the relationship between nicotine addiction and the neurotrophin pathway have been studied in dozens of publications especially dealing with tyrosine kinase (Trk) receptor A, postnatal rat hippocampus and Trk receptor signalling30, 31, 32. This evidence concerns the gene SORT1 and nicotine dependence.