Co-expression of serotonin type 3 receptor (5-HT3) and CB1 has been demonstrated within the BLA (Hermann et al., 2002; Morales and Backman, 2002; Morales et al., 2004). Between 16–36% of CB1-expressing neurons, depending on the subregion of the BLA, express transcript for 5-HT3 receptors. Conversely, 37–55% of 5-HT3 receptor-expressing neurons also express CB1 receptor transcript. These co-expressing neurons correspond to the GABAergic, high CB1-expressing population within the BLA (Morales et al., 2004).
