Figure 9.

Schema of excitatory and inhibitory recurrent network in the dentate gyrus. In the molecular layer close to the granule cell layer, glutamatergic terminals of mossy cell axons are densely distributed, and most of them express low levels of CB₁. The portions of granule cell dendrite in contact with mossy cell terminals express a high level of DGLα. In contrast, inhibitory terminals are sparsely distributed, and 30% of them express high levels of CB₁. The portions of granule cell dendrite with which inhibitory terminals are in contact express low levels of DGLα. Therefore, knock-out of DGLα may result in more selective deletion of retrograde synaptic suppression of recurrent excitatory network than that of CB₁ receptor.