Embryonic TCDD exposure disrupts neural network formation. Dorsal confocal images of axon tracts in control (A) and TCDD-exposed (B) embryos at 48 hpf. The brain parenchyma is marked by Hoechst staining (DNA, blue) and axon tracts are immunolabeled with an anti-acetylated α tubulin (α-tubulin) antibody (white and inverted black signal). Projections emanating from the optic neuropils (green shading and purple arrowheads) were reduced in TCDD-exposed embryos. The posterior commissure (yellow shading) appears defasciculated following TCDD exposure. Purkinje cells in the cerebellum (black arrowheads) were malformed in TCDD-exposed zebrafish relative to controls. Although the area covered by acetylated α-tubulin in the hindbrain was not statistically different between groups, we noted that the acetylated α-tubulin projections in the hindbrain (pink arrows) appear diminished in TCDD-exposed embryos. (C) Fold change of acetylated α-tubulin in the forebrain, optic tectum, cerebellum, hindbrain, and whole brain calculated relative to average α-tubulin area coverage in controls. Statistical significance determined by Welch’s t-test, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. n = 21–26 fish/group across 3 replicates. Anterior (Ant) is left in all confocal micrographs. First 2 panels containing confocal micrographs in A and B are at a 10x magnification. All other confocal micrographs are at a 10x magnification with a 2.5 digital zoom). Scale bar = 100 μm.
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