Zuh and Lovinger utilized an isolated neuron/synaptic bouton preparation to examine the effects of CB1 receptor activation on the regulation of GABAergic transmission in BLA principal neurons (Zhu and Lovinger, 2005). Application of Win 55212-2 to this preparation produced a rapidly reversible reduction in the frequency and amplitude of sIPSCs. These authors also found that blockade of the CB1 receptor with either AM 251 or SR141716 increased sIPSC frequency. This effect was eliminated when the post-synaptic neuron was filled with a calcium chelator or extracellular calcium concentrations were reduced, suggesting a tonic CB1 receptor activation via calcium-dependent, post-synaptic eCB production in this preparation. Recent work by Yoshida et al. demonstrated that DSI in the BA is absent in DAGLα knock-out mice, implicating 2-AG as the relevant eCB ligand mediating this form of eCB signaling (Yoshida et al., 2011).
