Layer-specific endocannabinoid-mediated LTD of GABAergic neurotransmission onto principal neurons in mouse visual cortex.

Visually induced endocannabinoid-mediated long-term depression of GABAergic neurotransmission (iLTD) mediates the maturation of GABAergic release in layer 2/3 of visual cortex. Here we examined whether the maturation of GABAergic transmission in other layers of visual cortex also requires endocannabinoids. The developmental plasticity of GABAergic neurotransmission onto the principal neurons in different layers of mouse visual cortex was examined in cortical slices by whole-cell recordings of IPSCs evoked by presynaptic inhibitory inputs. Theta burst stimulation of GABAergic inputs induced an endocannabinoid-mediated long-term depression of GABAergic neurotransmission onto pyramidal cells in layer 2/3 from postnatal day 10 to 30 and in layer 5 from P10 to 40 respectively, whereas that of GABAergic inputs did not induce iLTD onto star pyramidal neurons in layer 4 at any postnatal days, indicating that this plasticity is laminar specific. The developmental loss of iLTD paralleled the maturation of GABAergic inhibition in both layer 2/3 and layer 5. Visual deprivation delayed the developmental loss of iLTD in layer 3 and layer 5 during a critical period, while two day light exposure eliminated iLTD in both layers. Furthermore, the GABAergic synapses in layer 2/3 and layer 5 did not normally mature in the type 1 cannabinoid receptor knock-out mice, whereas those in layer 4 did not require endocannabinoid receptor for maturation. These results suggest that visually induced endocannabinoid-dependent iLTD mediates the maturation of GABAergic release in extra-granular layer rather than in granular layer of mouse visual cortex. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.