TRPV1 and major depressive disorder: Given the ubiquitous expression of TRPV1 throughout the brain, it is not surprising that TRPV1 has been implicated in several neurological and psychiatric disorders such as epilepsy, anxiety, and depression as well as drug-addiction disorders (Edwards, 2014; Singh et al., 2019; Escelsior et al., 2020; Allain et al., 2021; Asth et al., 2021; Zhou et al., 2021).