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Tao S, Liu L, Shi L, Li X, Shen P, Xun Q, Guo X, Yu Z, Wang J. Spatial learning and memory deficits in young adult mice exposed to a brief intense noise at postnatal age. J Otol 2015; 10:21-28. [PMID: 29937778 PMCID: PMC6002560 DOI: 10.1016/j.joto.2015.07.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 07/14/2015] [Indexed: 02/07/2023] Open
Abstract
Noise pollution is a major hazardous factor to human health and is likely harmful for vulnerable groups such as pre-term infants under life-support system in an intensive care unit. Previous studies have suggested that noise exposure impairs children's learning ability and cognitive performance and cognitive functions in animal models in which the effect is mainly attributed to the oxidant stress of noise on the cognitive brain. The potential role of noise induced hearing loss (NIHL), rather than the oxidant stress, has also been indicated by a depression of neurogenesis in the hippocampus long after a brief noise exposure, which produces only a tentative oxidant stress. It is not clear if noise exposure and NIHL during early development exerts a long term impact on cognitive function and neurogenesis towards adulthood. In the present study, a brief noise exposure at high sound level was performed in neonatal C57BL/6J mice (15 days after birth) to produce a significant amount of permanent hearing loss as proved 2 months after the noise. At this age, the noise-exposed animals showed deteriorated spatial learning and memory abilities and a reduction of hippocampal neurogenesis as compared with the control. The averaged hearing threshold was found to be strongly correlated with the scores for spatial learning and memory. We consider the effects observed are largely due to the loss of hearing sensitivity, rather than the oxidant stress, due to the long interval between noise exposure and the observations.
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Affiliation(s)
- Shan Tao
- Department of Physiology, Medical College of Southeast University, Nanjing, China
| | - Lijie Liu
- Department of Physiology, Medical College of Southeast University, Nanjing, China
| | - Lijuan Shi
- Department of Physiology, Medical College of Southeast University, Nanjing, China
| | - Xiaowei Li
- Department of Physiology, Medical College of Southeast University, Nanjing, China
| | - Pei Shen
- Department of Physiology, Medical College of Southeast University, Nanjing, China
| | - Qingying Xun
- Department of Physiology, Medical College of Southeast University, Nanjing, China
| | - Xiaojing Guo
- Department of Physiology, Medical College of Southeast University, Nanjing, China.,Children's Medical Center, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Zhiping Yu
- School of Human Communication Disorders, Dalhousie University, Halifax, Canada
| | - Jian Wang
- Department of Physiology, Medical College of Southeast University, Nanjing, China.,School of Human Communication Disorders, Dalhousie University, Halifax, Canada
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Cui B, Li K, Gai Z, She X, Zhang N, Xu C, Chen X, An G, Ma Q, Wang R. Chronic Noise Exposure Acts Cumulatively to Exacerbate Alzheimer's Disease-Like Amyloid-β Pathology and Neuroinflammation in the Rat Hippocampus. Sci Rep 2015; 5:12943. [PMID: 26251361 PMCID: PMC4528219 DOI: 10.1038/srep12943] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 07/10/2015] [Indexed: 11/27/2022] Open
Abstract
A putative etiological association exists between noise exposure and Alzheimer’s disease (AD). Amyloid-β (Aβ) pathology is thought to be one of the primary initiating factors in AD. It has been further suggested that subsequent dysregulation of Aβ may play a mechanistic role in the AD-like pathophysiology associated with noise exposure. Here, we used ELISA, immunoblotting, cytokine arrays, and RT-PCR, to examine both hippocampal Aβ pathology and neuroinflammation in rats at different time points after noise exposure. We found that chronic noise exposure significantly accelerated the progressive overproduction of Aβ, which persisted for 7 to 14 days after the cessation of exposure. This effect was accompanied by up-regulated expression of amyloid precursor protein (APP) and its cleavage enzymes, β- and γ-secretases. Cytokine analysis revealed that chronic noise exposure increased levels of tumor necrosis factor-α and the receptor for advanced glycation end products, while decreasing the expression of activin A and platelet-derived growth factor- AA. Furthermore, we found persistent elevations of glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1 expression that closely corresponded to the noise-induced increases in Aβ and neuroinflammation. These studies suggest that lifelong environmental noise exposure may have cumulative effects on the onset and development of AD.
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Affiliation(s)
- Bo Cui
- Department of Occupational Hygiene, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Kang Li
- Department of Occupational Hygiene, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Zhihui Gai
- 1] Department of Occupational Hygiene, Tianjin Institute of Health and Environmental Medicine, Tianjin, China [2] Shandong academy of occupational health and occupational medicine, Shandong academy of medical sciences, Jinan, China
| | - Xiaojun She
- Department of Occupational Hygiene, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Na Zhang
- Department of Occupational Hygiene, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Chuanxiang Xu
- Department of Occupational Hygiene, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Xuewei Chen
- Department of Occupational Hygiene, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Gaihong An
- Department of Occupational Hygiene, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Qiang Ma
- Department of Occupational Hygiene, Tianjin Institute of Health and Environmental Medicine, Tianjin, China
| | - Rui Wang
- Shandong academy of occupational health and occupational medicine, Shandong academy of medical sciences, Jinan, China
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53
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Olivito L, Saccone P, Perri V, Bachman JL, Fragapane P, Mele A, Huganir RL, De Leonibus E. Phosphorylation of the AMPA receptor GluA1 subunit regulates memory load capacity. Brain Struct Funct 2014; 221:591-603. [PMID: 25381005 PMCID: PMC4425615 DOI: 10.1007/s00429-014-0927-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/17/2014] [Indexed: 01/13/2023]
Abstract
Memory capacity (MC) refers to the number of elements one can maintain for a short retention interval. The molecular mechanisms underlying MC are unexplored. We have recently reported that mice as well as humans have a limited MC, which is reduced by hippocampal lesions. Here, we addressed the molecular mechanisms supporting MC. GluA1 AMPA-receptors (AMPA-R) mediate the majority of fast excitatory synaptic transmission in the brain and are critically involved in memory. Phosphorylation of GluA1 at serine residues S831 and S845 is promoted by CaMKII and PKA, respectively, and regulates AMPA-R function in memory duration. We hypothesized that AMPA-R phosphorylation may also be a key plastic process for supporting MC because it occurs in a few minutes, and potentiates AMPA-R ion channel function. Here, we show that knock-in mutant mice that specifically lack both of S845 and S831 phosphorylation sites on the GluA1 subunit had reduced MC in two different behavioral tasks specifically designed to assess MC in mice. This demonstrated a causal link between AMPA-R phosphorylation and MC. We then showed that information load regulates AMPA-R phosphorylation within the hippocampus, and that an overload condition associated with impaired memory is paralleled by a lack of AMPA-R phosphorylation. Accordingly, we showed that in conditions of high load, but not of low load, the pharmacological inhibition of the NMDA–CaMKII–PKA pathways within the hippocampus prevents memory as well as associated AMPA-R phosphorylation. These data provide the first identified molecular mechanism that regulates MC.
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Affiliation(s)
- Laura Olivito
- Institute of Genetics and Biophysics, CNR, Via P. Castellino 111, 80131, Naples, Italy
| | - Paola Saccone
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | - Valentina Perri
- Dipartimento di Biologia e Biotecnologie, Università degli Studi di Roma "La Sapienza", Rome, Italy
- Centro di Ricerca in Neurobiologia-D. Bovet, Università degli Studi di Roma "La Sapienza", Rome, Italy
| | - Julia L Bachman
- Department of Neuroscience and Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Hunterian 1001, 725 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Paola Fragapane
- Istituto di Biologia e Patologia Molecolare, CNR, Rome, Italy
| | - Andrea Mele
- Dipartimento di Biologia e Biotecnologie, Università degli Studi di Roma "La Sapienza", Rome, Italy
- Centro di Ricerca in Neurobiologia-D. Bovet, Università degli Studi di Roma "La Sapienza", Rome, Italy
| | - Richard L Huganir
- Department of Neuroscience and Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Hunterian 1001, 725 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Elvira De Leonibus
- Institute of Genetics and Biophysics, CNR, Via P. Castellino 111, 80131, Naples, Italy.
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy.
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Hu R, Huang D, Tong J, Liao Q, Hu Z, Ouyang W. Aspartic acid in the hippocampus: a biomarker for postoperative cognitive dysfunction. Neural Regen Res 2014; 9:143-52. [PMID: 25206795 PMCID: PMC4146156 DOI: 10.4103/1673-5374.125343] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/27/2013] [Indexed: 12/25/2022] Open
Abstract
This study established an aged rat model of cognitive dysfunction using anesthesia with 2% isoflurane and 80% oxygen for 2 hours. Twenty-four hours later, Y-maze test results showed that isoflurane significantly impaired cognitive function in aged rats. Gas chromatography-mass spectrometry results showed that isoflurane also significantly increased the levels of N,N-diethylacetamide, n-ethylacetamide, aspartic acid, malic acid and arabinonic acid in the hippocampus of isoflurane-treated rats. Moreover, aspartic acid, N,N-diethylacetamide, n-ethylacetamide and malic acid concentration was positively correlated with the degree of cognitive dysfunction in the isoflurane-treated rats. It is evident that hippocampal metabolite changes are involved in the formation of cognitive dysfunction after isoflurane anesthesia. To further verify these results, this study cultured hippocampal neurons in vitro, which were then treated with aspartic acid (100 μmol/L). Results suggested that aspartic acid concentration in the hippocampus may be a biomarker for predicting the occurrence and disease progress of cognitive dysfunction.
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Affiliation(s)
- Rong Hu
- Department of Anesthesia, Third Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Dong Huang
- Department of Anesthesia, Third Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Jianbin Tong
- Department of Anatomy & Neurobiology, Xiangya School of Medicine, Central South University, Changsha, Hunan Province, China
| | - Qin Liao
- Department of Anesthesia, Third Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Zhonghua Hu
- Department of Anesthesia, Third Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Wen Ouyang
- Department of Anesthesia, Third Xiangya Hospital, Central South University, Changsha, Hunan Province, China
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55
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Tzivian L, Winkler A, Dlugaj M, Schikowski T, Vossoughi M, Fuks K, Weinmayr G, Hoffmann B. Effect of long-term outdoor air pollution and noise on cognitive and psychological functions in adults. Int J Hyg Environ Health 2014; 218:1-11. [PMID: 25242804 DOI: 10.1016/j.ijheh.2014.08.002] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 08/20/2014] [Accepted: 08/26/2014] [Indexed: 10/24/2022]
Abstract
It has been hypothesized that air pollution and ambient noise might impact neurocognitive function. Early studies mostly investigated the associations of air pollution and ambient noise exposure with cognitive development in children. More recently, several studies investigating associations with neurocognitive function, mood disorders, and neurodegenerative disease in adult populations were published, yielding inconsistent results. The purpose of this review is to summarize the current evidence on air pollution and noise effects on mental health in adults. We included studies in adult populations (≥18 years old) published in English language in peer-reviewed journals. Fifteen articles related to long-term effects of air pollution and eight articles on long-term effects of ambient noise were extracted. Both exposures were separately shown to be associated with one or several measures of global cognitive function, verbal and nonverbal learning and memory, activities of daily living, depressive symptoms, elevated anxiety, and nuisance. No study considered both exposures simultaneously and few studies investigated progression of neurocognitive decline or psychological factors. The existing evidence generally supports associations of environmental factors with mental health, but does not suffice for an overall conclusion about the independent effect of air pollution and noise. There is a need for studies investigating simultaneously air pollution and noise exposures in association mental health, for longitudinal studies to corroborate findings from cross-sectional analyses, and for parallel toxicological and epidemiological studies to elucidate mechanisms and pathways of action.
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Affiliation(s)
- Lilian Tzivian
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.
| | - Angela Winkler
- Department of Neurology, University Hospital of Essen, University of Duisburg-Essen, Essen, Germany
| | - Martha Dlugaj
- Department of Neurology, University Hospital of Essen, University of Duisburg-Essen, Essen, Germany
| | - Tamara Schikowski
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany; Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland
| | - Mohammad Vossoughi
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Kateryna Fuks
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Gudrun Weinmayr
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Barbara Hoffmann
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany; Medical Faculty, Heinrich Heine University of Düsseldorf, Düsseldorf, Germany
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56
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Zhvania MG, Bikashvili TZ, Japaridze NJ, Lazrishvili II, Ksovreli M. White noise and neuronal porosome complex: transmission electron microscopic study. Discoveries (Craiova) 2014; 2:e25. [PMID: 32309553 PMCID: PMC6941563 DOI: 10.15190/d.2014.17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In the present electron microscopic study the effect of continuous white noise on the morphology of synapses and neuronal porosome complex (the neurotransmitter-release or secretory machinery) in two subcortical auditory brain regions - colliculus inferior and medial geniculate body in cat, were investigated. Several morphological alterations in some synapses were detected in both subcortical areas. These alterations mainly indicate to the decrease of functional activity of synapses. Rarely important pathological modifications in pre- and post-synaptic regions were detected. In addition to descriptive studies, the morphometric analysis of porosome diameter and depth was performed in colliculus inferior and medial geniculate body. The results revealed that while white noise has no effect on the porosome diameter and depth in colliculus inferior, it provokes significant alterations in the morphology of porosome complex in medial geniculate body. In particular, the significant increase of porosome depth in this nucleus may reflect the alteration in neurotransmission.
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Affiliation(s)
- Mzia G Zhvania
- Institute of Chemical Biology, Ilia State University, 3/5 K. Cholokashvili Avenue, 0162 Tbilisi, Georgia.,I. Beritashvili Center of Experimental Biomedicine, 14 Gotua Street, 0160 Tbilisi, Georgia
| | - Tamar Z Bikashvili
- I. Beritashvili Center of Experimental Biomedicine, 14 Gotua Street, 0160 Tbilisi, Georgia
| | - Nadezhda J Japaridze
- I. Beritashvili Center of Experimental Biomedicine, 14 Gotua Street, 0160 Tbilisi, Georgia.,New Vision University, 1a, Mikeladze Street, 0159 Tbilisi, Georgia
| | - Ilia I Lazrishvili
- I. Beritashvili Center of Experimental Biomedicine, 14 Gotua Street, 0160 Tbilisi, Georgia
| | - Mariam Ksovreli
- Institute of Chemical Biology, Ilia State University, 3/5 K. Cholokashvili Avenue, 0162 Tbilisi, Georgia
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Role of NMDA receptors in noise-induced tau hyperphosphorylation in rat hippocampus and prefrontal cortex. J Neurol Sci 2014; 340:191-7. [DOI: 10.1016/j.jns.2014.03.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/22/2014] [Accepted: 03/13/2014] [Indexed: 11/23/2022]
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58
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Zheng Y, Meng M, Zhao C, Liao W, Zhang Y, Wang L, Wen E. Impact of environmental noise on growth and neuropsychological development of newborn rats. Anat Rec (Hoboken) 2014; 297:949-54. [PMID: 24610866 DOI: 10.1002/ar.22872] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 09/06/2013] [Accepted: 09/22/2013] [Indexed: 11/07/2022]
Abstract
We aimed to investigate the effects of environmental noise exposure on the growth and neuropsychological development in neonatal rats. Twenty-four postnatal 7-day-old Sprague-Dawley rats were randomly assigned into control, high-noise and reduced noise groups. The rats in the high-noise group were exposed to 90 dB white noise, and those in the control group were grown under standard condition, while those in the reduced noise group were exposed to standard condition with sound-absorbing cotton. Ten, 15, and 20 days post noise exposure, both the body weight and length of the rats in high-noise group were lower than those in the control and reduced noise groups, respectively. The secretion of growth hormone was significantly decreased in the rats exposed to high noise environment, compared to those exposed to standard condition and reduced noise. More interestingly, the swimming distance was apparently increased and the swimming speed was significantly decreased in high-noise group compared with those in control and reduced noise groups. Importantly, the mRNA and protein levels of SYP in the rats hippocampus were significantly decreased in high-noise group compare with those in control and reduced noise groups. Similarly, the positive expression of SYP in the CA1 region of hippocampus was also significantly decreased in the high noise group rats. In conclusion, our results demonstrated that high noise exposure could decrease the production of growth hormone and SYP in neonatal rats, which may retard the growth of weight and length and the capability of learning and memory.
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Affiliation(s)
- Yanyan Zheng
- Department of Pediatrics, Xinqiao Hospital, The Third Military Medical University, Chongqing, 400037, People's Republic of China
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60
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Chronic noise exposure and Alzheimer disease: Is there an etiological association? Med Hypotheses 2013; 81:623-6. [DOI: 10.1016/j.mehy.2013.07.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 06/27/2013] [Accepted: 07/05/2013] [Indexed: 11/19/2022]
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61
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Cui B, Zhu L, She X, Wu M, Ma Q, Wang T, Zhang N, Xu C, Chen X, An G, Liu H. Chronic noise exposure causes persistence of tau hyperphosphorylation and formation of NFT tau in the rat hippocampus and prefrontal cortex. Exp Neurol 2012; 238:122-9. [PMID: 22971273 DOI: 10.1016/j.expneurol.2012.08.028] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 08/05/2012] [Accepted: 08/28/2012] [Indexed: 10/27/2022]
Abstract
The non-auditory effects of noise exposure on the central nervous system have been established both epidemiologically and experimentally. Chronic noise exposure (CNE) has been associated with tau hyperphosphorylation and Alzheimer's disease (AD)-like pathological changes. However, experimental evidence for these associations remains limited. The aim of the current study was to explore the effects of CNE [100 dB sound pressure level (SPL) white noise, 4 h/d×14 d] on tau phosphorylation in the rat hippocampus and the prefrontal cortex. Forty-eight male Wistar rats were randomly assigned to two groups: a noise-exposed group and a control group. The levels of radioimmunoprecipitation assay (RIPA)-soluble and RIPA-insoluble phosphorylated tau at Ser202, Ser396, Ser404, and Ser422 in the hippocampus and the prefrontal cortex were measured at different time points (days 0, 3, 7, and 14) after the end of the last noise exposure. Exposure to white noise for 14 consecutive days significantly increased the levels of tau phosphorylation at Ser202, Ser396, Ser404, and Ser422, the sites typically phosphorylated in AD brains, in the hippocampus and the prefrontal cortex. Tau hyperphosphorylation persisted for 7 to 14 d after the cessation of noise exposure. These alterations were also concomitant with the generation of pathological neurofibrillary tangle (NFT) tau 3, 7 and 14 d after the end of the stimulus. Furthermore, lasting increases in proteins involved in hyperphosphorylation, namely glycogen synthase kinase 3β (GSK3β) and protein phosphatase 2A (PP2A), were found to occur in close correspondence with increase in tau hyperphosphorylation. The results of this study show that CNE leads to long-lasting increases in non-NFT hyperphosphorylated tau and delayed formation of misfolded NFT tau in the hippocampus and the prefrontal cortex. Our results also provide evidence for the involvement of GSK3β and PP2A in these processes.
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Affiliation(s)
- Bo Cui
- Department of Occupational Hygiene, Institute of Health and Environmental Medicine, Academy of Military Medical Sciences, Tianjin, China.
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Corticotropin-releasing factor receptor-dependent effects of repeated stress on tau phosphorylation, solubility, and aggregation. Proc Natl Acad Sci U S A 2012; 109:6277-82. [PMID: 22451915 DOI: 10.1073/pnas.1203140109] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Exposure and/or sensitivity to stress have been implicated as conferring risk for development of Alzheimer's disease (AD). Although the basis for such a link remains unclear, we previously reported differential involvement of corticotropin-releasing factor receptor (CRFR) 1 and 2 in acute stress-induced tau phosphorylation (tau-P) and solubility in the hippocampus. Here we examined the role of CRFRs in tau-P induced by repeated stress and the structural manifestations of altered tau solubility. Robust tau-P responses were seen in WT and CRFR2 null mice exposed to repeated stress, which were sustained at even 24 h after the final stress exposure. A portion of phosphorylated tau in these mice was sequestered in detergent-soluble cellular fractions. In contrast, CRFR1 and CRFR double-KO mice did not exhibit repeated stress-induced alterations in tau-P or solubility. Similarly, treatment with CRFR1 antagonist attenuated repeated stress-induced tau-P. Using histochemical approaches in a transgenic CRFR1 reporter mouse line, we found substantial overlap between hippocampal CRFR1 expression and cells positive for phosphorylated tau after exposure to repeated stress. Ultrastructural analysis of negatively stained extracts from WT and CRFR2 null mice identified globular aggregates that displayed positive immunogold labeling for tau-P, as well as conformational changes in tau (MC1) seen in early AD. Given that repeated stress exposure results in chronic increases in hippocampal tau-P and its sequestration in an insoluble (and potentially prepathogenic) form, our data may define a link between stress and an AD-related pathogenic mechanism.
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