BDNF and major depressive disorder: For this purpose, in post-traumatic stress syndrome (PTSD), CBD finds applicability by blocking FAAH and increasing available AEA [167,168,169]; in depression, CBD alleviates symptoms by stimulating serotoninergic neurotransmission, mediated by 5-HT1A, and by activating the BDNF-TrkB complex [170,171,172], whereas in anxiety and fear, these beneficial effects are mediated by the same 5-HT1A receptor, but also by GABAA receptors, respectively, by inhibiting the enzymatic activity of iNOS and FAAH [173].