DFP exposure caused increased NR2B-NMDA subunit receptor accumulation combined with decreased gephyrin and GABA signaling. (a) As experimental set-up, 5 dpf larvae were exposed to either 15 µM DFP or vehicle (DMSO) for 6 h, prior to being processed for NR2B-NMDA, gephyrin or GAD 65/67 immunolabeling. (b) Scheme of 5 dpf larva head highlighting the tectal neuropils in green. (c,d) NR2B-NMDA receptor immunolabelling of 5 dpf larvae brains exposed to either DMSO (c) or 15 µM DFP (d). Scale bar: 5 µm. (e) Quantification of NR2B-NMDA puncta density in 5 dpf larvae treated for 6 h with either DMSO (N = 4; n = 22) or 15 µM DFP (N = 4; n = 26) (Mann Whitney : ****, p < 0.0001). (f) Scheme of 5 dpf larva head highlighting the tectal neuropils in green. (g,h) Gephyrin immunolabelling of 5 dpf larvae brains exposed to either DMSO (g) or 15 µM DFP (h). Scale bar: 5 µm. (i) Quantification of gephyrin puncta density in 5 dpf larvae treated for 6 h with either DMSO (N = 4; n = 18) or 15 µM DFP (N = 4; n = 18) (Student unpaired t-test: **, p < 0.01). (j) Scheme of 5 dpf larva head highlighting stratum periventriculare in blue and green. (k,l) GAD65/67 immunolabelling of neurons in the optic tectum of 5 dpf larvae brains exposed to either DMSO (k) or 15 µM DFP (l). Scale bar :10 µm. (m) Quantification of the density of neurons expressing GAD65/67 protein in the optic tectum of 5 dpf larvae exposed to either DMSO (N = 4; n = 18) or 15 µM DFP (N = 4; n = 19) (Student unpaired t-test : **, p < 0.01). N = number of larvae and n = number of slices.
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