5-HT(2C) receptor RNA editing in the amygdala of C57BL/6J, DBA/2J, and BALB/cJ mice

Post-transcriptional RNA editing of the G-protein coupled 5-hydroxytryptamine-2C (5-HT(2C)) receptor predicts an array of 24 receptor isoforms, some of which are characterized by reduced constitutive activity and potency to initiate intracellular signaling. The amygdala is integral to anxiety, fear, and related psychiatric diseases. Activation of 5-HT(2C) receptors within the amygdala is anxiogenic. Here, we describe the RNA editing profiles from amygdala of two inbred mouse strains (BALB/cJ and DBA/2J) known to be more anxious than a third (C57BL/6J). We confirmed the strain anxiety differences using light<-->dark exploration, and we discovered that BALB/cJ and DBA/2J are each characterized by a higher functioning RNA editing profile than C57BL/6J. BALB/cJ and DBA/2J exhibit a roughly two-fold reduction in C site editing, and a corresponding two-fold reduction in the edited isoform VSV. C57BL/6J is characterized by a relative decrease in the unedited highly functional isoform INI. We estimated the heritability of editing at the C site to be approximately 40%. By sequencing genomic DNA, we found complete conservation between C57BL/6J, BALB/cJ, DBA/2J and 37 other inbred strains for the RNA edited region of Htr2c, suggesting Htr2c DNA sequence does not influence variation in Htr2c RNA editing between inbred strains of mice. We did, however, discover that serotonin turnover is reduced in BALB/cJ and DBA/2J, consistent with emerging evidence that synaptic serotonin levels regulate RNA editing. These results encourage further study of the causes and consequences of 5-HT(2C) receptor RNA editing in the amygdala of mice.