In addition, the anterior division of the BNST is rich in CRF receptor type 1 (CRFR1), whereas the posterior division is richer in CRF receptor type 2 (CRFR2) [43], and a dysbalance between these receptors may contribute to hyperactivity of the HPA axis, anxiety, and depression, which can be observed during nicotine withdrawal [57]. This evidence concerns the gene CRHR1 and depressive disorder.