In vivo exposure to cocaine or methamphetamine decreases GABABR-activated GIRK currents in VTA neurons (Arora et al., 2011; Padgett et al., 2012) and cortical neurons (Hearing et al., 2013), all appearing to result from reduced surface expression of GIRK channels. For VTA GABA neurons and PFC pyramidal neurons, a change in phosphorylation of the GABAB receptor may guide the change in GABABR-activated GIRK currents (Hearing et al., 2013; Padgett et al., 2012). However, the subcellular mechanism underlying the decrease in GABABR-activated GIRK currents in VTA DA neurons is not well understood. In rats sensitized to psychostimulants, mRNA for SNX27b (Mrt1b) increases (Kajii et al., 2003), raising the possibility that some of these effects of psychostimulants may be mediated by SNX27.
