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. Author manuscript; available in PMC: 2008 Jun 21.
Published in final edited form as: Neuron. 2007 Jun 21;54(6):889–903. doi: 10.1016/j.neuron.2007.05.015

Figure 2. GAD67-mediated GABA synthesis is limiting for perisomatic synapse maturation but not its maintenance.

Figure 2

A1, Control basket cell (green) at EP24 with exuberant innervation field characterized by extensive branching, dense boutons along axons (A2), and terminal branches (asterisks, A3) with prominent and clustered boutons (arrowheads) around pyramidal cell somata (NeuN immunostaining, red). B, Gad1−/− basket cell show overall similar axon arbor size and morphology (B1) but reduced axon branching (B2), terminal branching, bouton size and density (B3, arrow indicates larger inter-bouton intervals). C, Inactivation of only one Gad1 allele in basket cells yields a phenotype comparable to of Gad1−/− cells. A3, B3, C3 are from boxed regions in A2, B2, C2. A4, Immuno-EM of a typical GFP-labeled axonal bouton in a control basket cell, which forms symmetric synaptic contacts (arrowheads) with synaptic clefts, vesicle clustering, and thickening of the postsynaptic membrane. In Gad1−/− basket cells (B4), it is difficult to identify vesicles within the bouton-like structures and evidence of synaptic specialization throughout the bouton (arrow). Note that a neighboring GFP-negative symmetric synapse (arrowhead) from a Gad1+/+ cell appears entirely normal. Scale bar: A1, B1, C1: 50 μm; A2, B2, C2: 10 μm; A3, B3, C3: 5 μm; A4, B4: 0.5 μm. D–E, When transfected from EP16-24, bouton density and size are significantly reduced in Gad1−/− cells (7 basket cells and 50 pyramidal somata) and Gad1+/− cells (7 basket cells and 45 pyramidal somata) compared to aged-matched controls (8 basket cells and 50 pyramidal somata; One-way Anova, posthoc Dunn’s test p<0.05; also see Sppl Fig 3). When transfected from EP26-32, however, both parameters are unaffected in Gad1−/− cells (7 basket cells and 50 pyramidal somata) as compared to controls (7 basket cells and 45 pyramidal somata; Mann-Whitney U test, p>0.1; also see images in Sppl Fig 4). F, When transfected from EP16-24, Gad1−/− and Gad1+/− cells show reduced terminal branching compared to controls quantified as in Chattopadhyaya et al., 2004 (One-way Anova, posthoc Dunn’s test, p<0.05). When transfected from EP26-32, however, terminal branch complexity is maintained in Gad1−/− cells (Mann-Whitney U test, P>0.1).