Figure 4. Quantitatively differential distribution of the molecular players of retrograde 2-AG signaling in cortical areas.

A) Laminar distribution of DGL-α in association with glutamatergic synapses in the hippocampus (Katona et al., 2006) and B) in the neocortex (courtesy of Barna Dudok). C,D) In the amygdala, high density of DGL-α occurs at invaginating - but not at flat - GABAergic synapses (C) as well as at glutamatergic (D) axospinous contacts (Yoshida et al., 2011). E) In situ hybridization in the hippocampus reveals high levels of CB₁ mRNA in interneurons, lower levels in CA3, and even lower in CA1 pyramidal cells. Dentate granule cells are devoid of labeling. F) Immunostaining for the CB₁ receptor protein reveals a striking laminar pattern associated with both GABAergic and glutamatergic terminals (Katona et al., 2006). G-L) Great variability in MGL content between glutamatergic pathways is revealed by double-labeling for vGluT₁ (green) and MGL (red). No co-localization in the dentate inner molecular layer (G,H), but a high degree of overlap in recurrent axon terminals in CA3 (I,J), and moderate co-localization in Schaffer collateral terminals in CA1 (K,L) (Uchigashima et al., 2011). The individual figures have been modified from the originals with permission from the authors.