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Yu D, Zhou H, Zou L, Jiang Y, Wu X, Jiang L, Zhou Q, Yang Y, Xu L, Mao R. Hippocampal Administration of Levothyroxine Impairs Contextual Fear Memory Consolidation in Rats. Front Cell Neurosci 2017; 11:223. [PMID: 28824379 PMCID: PMC5534464 DOI: 10.3389/fncel.2017.00223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 07/13/2017] [Indexed: 12/17/2022] Open
Abstract
Thyroid hormone (TH) receptors are highly distributed in the hippocampus, which plays a vital role in memory processes. However, how THs are involved in the different stages of memory process is little known. Herein, we used hippocampus dependent contextual fear conditioning to address the effects of hippocampal THs on the different stages of fear memory. First, we found that a single systemic levothyroxine (LT4) administration increased the level of free triiodothyronine (FT3) and free tetraiodothyroxine (FT4) not only in serum but also in hippocampus. In addition, a single systemic LT4 administration immediately after fear conditioning significantly impaired fear memory. These results indicated the important role of hippocampal THs in fear memory process. To further confirm the effects of hippocampal THs on the different stages of fear memory, LT4 (0.4 μg/μl, 1 μl/side) was injected bilaterally into hippocampus. Rats given LT4 into hippocampus before training or tests had no effect on the acquisition or retrieval of fear memory, however rats given LT4 into hippocampus either immediately or 2 h after training showed being significantly impaired fear memory, which demonstrated LT4 administration into hippocampus impairs the consolidation but has no effect on the acquisition and retrieval of fear memory. Furthermore, hippocampal injection of LT4 did not affect rats’ locomotor activity, thigmotaxis and THs level in prefrontal cortex (PFC) and serum. These findings may have important implications for understanding mechanisms underlying contribution of THs to memory disorders.
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Affiliation(s)
- Dafu Yu
- Department of Nuclear Medicine, First People's Hospital of Yunnan ProvinceKunming, China.,Laboratory of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of SciencesKunming, China
| | - Heng Zhou
- Laboratory of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of SciencesKunming, China.,School of Life Sciences, University of Science and Technology of ChinaHefei, China
| | - Lin Zou
- Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical UniversityChongqing, China
| | - Yong Jiang
- Department of Nuclear Medicine, First People's Hospital of Yunnan ProvinceKunming, China
| | - Xiaoqun Wu
- Respiratory Department, First People's Hospital of Yunnan ProvinceKunming, China
| | - Lizhu Jiang
- Laboratory of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of SciencesKunming, China.,Department of Neuropsychopathy, Clinical Medical School, Dali UniversityDali, China
| | - Qixin Zhou
- Laboratory of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of SciencesKunming, China
| | - Yuexiong Yang
- Laboratory of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of SciencesKunming, China
| | - Lin Xu
- Laboratory of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of SciencesKunming, China
| | - Rongrong Mao
- Laboratory of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of SciencesKunming, China
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Flamant F, Gauthier K, Richard S. Genetic Investigation of Thyroid Hormone Receptor Function in the Developing and Adult Brain. Curr Top Dev Biol 2017; 125:303-335. [PMID: 28527576 DOI: 10.1016/bs.ctdb.2017.01.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Thyroid hormones exert a broad influence on brain development and function, which has been extensively studied over the years. Mouse genetics has brought an important contribution, allowing precise analysis of the interplay between TRα1 and TRβ1 nuclear receptors in neural cells. However, the exact contribution of each receptor, the possible intervention of nongenomic signaling, and the nature of the genetic program that is controlled by the receptors remain poorly understood.
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Affiliation(s)
- Frédéric Flamant
- Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon 1, CNRS UMR 5242, INRA USC 1370, Ecole Normale Supérieure de Lyon, Lyon cedex, France.
| | - Karine Gauthier
- Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon 1, CNRS UMR 5242, INRA USC 1370, Ecole Normale Supérieure de Lyon, Lyon cedex, France
| | - Sabine Richard
- Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon 1, CNRS UMR 5242, INRA USC 1370, Ecole Normale Supérieure de Lyon, Lyon cedex, France
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Perfluoroalkyl substances, thyroid hormones, and neuropsychological status in older adults. Int J Hyg Environ Health 2016; 220:679-685. [PMID: 28065522 DOI: 10.1016/j.ijheh.2016.12.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 12/08/2016] [Accepted: 12/21/2016] [Indexed: 01/09/2023]
Abstract
Minimal data exist regarding the neurotoxicity of perfluoroalkyl substances (PFASs) in aging populations and the possible mediating effects of thyroid hormones (THs). Hence, the aims of this study were to: (i) assess associations between PFASs and neuropsychological function, and (ii) determine if such associations are mediated by changes in circulating THs in an aging population. We measured perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), total thyroxine (T4) and free thyroxine (fT4) in serum and performed neuropsychological tests in 126 men and women aged 55-74 years and living in upper Hudson River communities. Multivariable linear regressions were conducted to assess associations between PFASs and neuropsychological test scores. Mediation analyses were performed in a subset of 87 participants for whom information was available on both PFASs and THs. We calculated TH-mediated, non-TH mediated, and total effects of PFASs on neuropsychological test scores. Higher PFOA was associated with better performance in tasks of the California Verbal Learning Test and the Wisconsin Card Sorting Test. Higher PFOS was associated with improved performance in a Wechsler Memory Scale subtest and Block Design Subtest (BDT) total scores. There was no evidence of mediation by THs for PFOA-neuropsychological function associations. However, T4 and fT4 partially mediated the protective effect of PFOS on BDT total scores. Our findings do not suggest that PFASs are associated with poor neuropsychological function. There was some evidence of mediation for the association between PFASs and neuropsychological functions by THs, although some other modes of action also appear likely.
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