Receptor subunits for 3 other neurotransmitter systems, dopamine, acetylcholine and serotonin, all had reduced gene expression. Acetylcholine injected into the ventral lateral PAG causes hypotension (Delindo, et al., 2010), indicating that acetylcholine signaling can limit physiological changes associated with anxiety and stress. Genes for serotonin signaling were also largely decreased in the DRN of adolescent alcohol drinking P rats (McClintick et al., 2015). Release of serotonin in the dorsal lateral PAG inhibits stress induced sympathetic activity via the Htr1a receptor (Johnson et al., 2004), which was decreased −1.5 fold in these binge drinking animals. Adra1a, an alpha-adrenergic receptor subunit gene, also had decreased expression. Since norepinephrine injected into the PAG has an anxiolytic effect (Pelosi, et al., 2009) the decrease in Adra1a could make these animals more prone to anxiety in stressful situations.
