RRC ID 65624
Author Kimura E, Kohda M, Maekawa F, Fujii-Kuriyama Y, Tohyama C.
Title Neurons expressing the aryl hydrocarbon receptor in the locus coeruleus and island of Calleja major are novel targets of dioxin in the mouse brain.
Journal Histochem Cell Biol
Abstract The aryl hydrocarbon receptor (AhR) acts as a receptor that responds to ligands, including dioxin. The AhR-ligand complex translocates from the cytoplasm into the nucleus to induce gene expression. Because dioxin exposure impairs cognitive and neurobehavioral functions, AhR-expressing neurons need to be identified for elucidation of the dioxin neurotoxicity mechanism. Immunohistochemistry was performed to detect AhR-expressing neurons in the mouse brain and confirm the specificity of the anti-AhR antibody using Ahr-/- mice. Intracellular distribution of AhR and expression level of AhR-target genes, Cyp1a1, Cyp1b1, and Ahr repressor (Ahrr), were analyzed by immunohistochemistry and quantitative RT-PCR, respectively, using mice exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The mouse brains were shown to harbor AhR in neurons of the locus coeruleus (LC) and island of Calleja major (ICjM) during developmental period in Ahr+/+ mice but not in Ahr-/- mice. A significant increase in nuclear AhR of ICjM neurons but not LC neurons was found in 14-day-old mice compared to 5- and 7-day-old mice. AhR was significantly translocated into the nucleus in LC and ICjM neurons of TCDD-exposed adult mice. Additionally, the expression levels of Cyp1a1, Cyp1b1, and Ahrr genes in the brain, a surrogate of TCDD in the tissue, were significantly increased by dioxin exposure, suggesting that dioxin-activated AhR induces gene expression in LC and ICjM neurons. This histochemical study shows the ligand-induced nuclear translocation of AhR at the single-neuron level in vivo. Thus, the neurotoxicological significance of the dioxin-activated AhR in the LC and ICjM warrants further studies.
Volume 156(2)
Pages 147-163
Published 2021-8-1
DOI 10.1007/s00418-021-01990-1
PII 10.1007/s00418-021-01990-1
PMID 33963922
PMC PMC8397641
MeSH Animals Basic Helix-Loop-Helix Transcription Factors / analysis Basic Helix-Loop-Helix Transcription Factors / genetics* Basic Helix-Loop-Helix Transcription Factors / metabolism Brain / metabolism* Dioxins / metabolism* Female Immunohistochemistry Locus Coeruleus / metabolism* Male Mice Mice, Inbred C57BL Mice, Knockout Neurons / metabolism* Receptors, Aryl Hydrocarbon / analysis Receptors, Aryl Hydrocarbon / genetics* Receptors, Aryl Hydrocarbon / metabolism
IF 3.418
Mice RBRC01710