GJB6 and major depressive disorder: In animals under chronic stress and in humans with major depression) there are drastically low levels of astrocytic gap junction proteins connexin 43 (Cx43) and connexin 30 (Cx30) in the prefrontal cortex (PFC) as compared to controls (Ernst et al., 2011; Sun et al., 2012; Miguel-Hidalgo et al., 2014, 2018; Nagy et al., 2016).