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Santiago NA, He B, Howard SL, Beaudin S, Strupp BJ, Smith DR. Developmental Manganese Exposure Causes Lasting Attention Deficits Accompanied by Dysregulation of mTOR Signaling and Catecholaminergic Gene Expression in Brain Prefrontal Cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.16.549215. [PMID: 37503220 PMCID: PMC10370122 DOI: 10.1101/2023.07.16.549215] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Elevated manganese (Mn) exposure is associated with attentional deficits in children, and is an environmental risk factor for attention deficit hyperactivity disorder (ADHD). We have shown that developmental Mn exposure causes lasting attention and sensorimotor deficits in a rat model of early childhood Mn exposure, and that these deficits are associated with a hypofunctioning catecholaminergic system in the prefrontal cortex (PFC), though the mechanistic basis for these deficits is not well understood. To address this, male Long-Evans rats were exposed orally to Mn (50 mg/kg/d) over PND 1-21 and attentional function was assessed in adulthood using the 5-Choice Serial Reaction Time Task. Targeted catecholaminergic system and epigenetic gene expression, followed by unbiased differential DNA methylation and gene regulation expression transcriptomics in the PFC, were performed in young adult littermates. Results show that developmental Mn exposure causes lasting focused attention deficits that are associated with reduced gene expression of tyrosine hydroxylase, dopamine transporter, and DNA methyltransferase 3a. Further, developmental Mn exposure causes broader lasting methylation and gene expression dysregulation associated with epigenetic regulation, inflammation, cell development, and hypofunctioning catecholaminergic neuronal systems. Pathway enrichment analyses uncovered mTOR and Wnt signaling pathway genes as significant transcriptomic regulators of the Mn altered transcriptome, and Western blot of total, C1 and C2 phospho-mTOR confirmed mTOR pathway dysregulation. Our findings deepen our understanding of the mechanistic basis of how developmental Mn exposure leads to lasting catecholaminergic dysfunction and attention deficits, which may aid future therapeutic interventions of environmental exposure associated disorders. Significance Statement Attention deficit hyperactivity disorder (ADHD) is associated with environmental risk factors, including exposure to neurotoxic agents. Here we used a rodent model of developmental manganese (Mn) exposure producing lasting attention deficits to show broad epigenetic and gene expression changes in the prefrontal cortex, and to identify disrupted mTOR and Wnt signaling pathways as a novel mechanism for how developmental Mn exposure may induce lasting attention and catecholaminergic system impairments. Importantly, our findings establish early development as a critical period of susceptibility to lasting deficits in attentional function caused by elevated environmental toxicant exposure. Given that environmental health threats disproportionately impact communities of color and low socioeconomic status, our findings can aid future studies to assess therapeutic interventions for vulnerable populations.
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Fernandes J, Hao L, Bijli KM, Chandler JD, Orr M, Hu X, Jones DP, Go YM. From the Cover: Manganese Stimulates Mitochondrial H2O2 Production in SH-SY5Y Human Neuroblastoma Cells Over Physiologic as well as Toxicologic Range. Toxicol Sci 2016; 155:213-223. [PMID: 27701121 DOI: 10.1093/toxsci/kfw196] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Manganese (Mn) is an abundant redox-active metal with well-characterized mitochondrial accumulation and neurotoxicity due to excessive exposures. Mn is also an essential co-factor for the mitochondrial antioxidant protein, superoxide dismutase-2 (SOD2), and the range for adequate intake established by the Institute of Medicine Food and Nutrition Board is 20% of the interim guidance value for toxicity by the Agency for Toxic Substances and Disease Registry, leaving little margin for safety. To study toxic mechanisms over this critical dose range, we treated human neuroblastoma SH-SY5Y cells with a series of MnCl2 concentrations (from 0 to 100 μM) and measured cellular content to compare to human brain Mn content. Concentrations ≤10 μM gave cellular concentrations comparable to literature values for normal human brain, whereas concentrations ≥50 μM resulted in values comparable to brains from individuals with toxic Mn exposures. Cellular oxygen consumption rate increased as a function of Mn up to 10 μM and decreased with Mn dose ≥50 μM. Over this range, Mn had no effect on superoxide production as measured by aconitase activity or MitoSOX but increased H2O2 production as measured by MitoPY1. Consistent with increased production of H2O2, SOD2 activity, and steady-state oxidation of total thiol increased with increasing Mn. These findings have important implications for Mn toxicity by re-directing attention from superoxide anion radical to H2O2-dependent mechanisms and to investigation over the entire physiologic range to toxicologic range. Additionally, the results show that controlled Mn exposure provides a useful cell manipulation for toxicological studies of mitochondrial H2O2 signaling.
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Affiliation(s)
| | | | | | | | | | | | | | - Young-Mi Go
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Emory University, Atlanta, Georgia 30322
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Foster ML, Bartnikas TB, Johnson LC, Herrera C, Pettiglio MA, Keene AM, Taylor MD, Dorman DC. Pharmacokinetic evaluation of the equivalency of gavage, dietary, and drinking water exposure to manganese in F344 rats. Toxicol Sci 2015; 145:244-51. [PMID: 25724921 DOI: 10.1093/toxsci/kfv047] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Concerns exist as to whether individuals may be at greater risk for neurotoxicity following increased manganese (Mn) oral intake. The goals of this study were to determine the equivalence of 3 methods of oral exposure and the rate (mg Mn/kg/day) of exposure. Adult male rats were allocated to control diet (10 ppm), high manganese diet (200 ppm), manganese-supplemented drinking water, and manganese gavage treatment groups. Animals in the drinking water and gavage groups were given the 10 ppm manganese diet and supplemented with manganese chloride (MnCl(2)) in drinking water or once-daily gavage to provide a daily manganese intake equivalent to that seen in the high-manganese diet group. No statistically significant difference in body weight gain or terminal body weights was seen. Rats were anesthetized following 7 and 61 exposure days, and samples of bile and blood were collected. Rats were then euthanized and striatum, olfactory bulb, frontal cortex, cerebellum, liver, spleen, and femur samples were collected for chemical analysis. Hematocrit was unaffected by manganese exposure. Liver and bile manganese concentrations were elevated in all treatment groups on day 61 (relative to controls). Increased cerebellum manganese concentrations were seen in animals from the high-manganese diet group (day 61, relative to controls). Increased (relative to all treatment groups) femur, striatum, cerebellum, frontal cortex, and olfactory bulb manganese concentrations were also seen following gavage suggesting that dose rate is an important factor in the pharmacokinetics of oral manganese. These data will be used to refine physiologically based pharmacokinetic models, extending their utility for manganese risk assessment by including multiple dietary exposures.
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Affiliation(s)
- Melanie L Foster
- *North Carolina State University, College of Veterinary Medicine, 1060 William Moore Drive, Raleigh, North Carolina 27607, USA, Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Rm. 522, Providence, Rhode Island 02912, USA, Afton Chemical Corporation, 500 Spring Street, Richmond, Virginia 23219, USA and Nickel Producers Environmental Research Association (NiPERA), 2525 Meridian Parkway, Suite 240 Durham, North Carolina 27713, USA
| | - Thomas B Bartnikas
- *North Carolina State University, College of Veterinary Medicine, 1060 William Moore Drive, Raleigh, North Carolina 27607, USA, Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Rm. 522, Providence, Rhode Island 02912, USA, Afton Chemical Corporation, 500 Spring Street, Richmond, Virginia 23219, USA and Nickel Producers Environmental Research Association (NiPERA), 2525 Meridian Parkway, Suite 240 Durham, North Carolina 27713, USA
| | - Laura C Johnson
- *North Carolina State University, College of Veterinary Medicine, 1060 William Moore Drive, Raleigh, North Carolina 27607, USA, Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Rm. 522, Providence, Rhode Island 02912, USA, Afton Chemical Corporation, 500 Spring Street, Richmond, Virginia 23219, USA and Nickel Producers Environmental Research Association (NiPERA), 2525 Meridian Parkway, Suite 240 Durham, North Carolina 27713, USA
| | - Carolina Herrera
- *North Carolina State University, College of Veterinary Medicine, 1060 William Moore Drive, Raleigh, North Carolina 27607, USA, Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Rm. 522, Providence, Rhode Island 02912, USA, Afton Chemical Corporation, 500 Spring Street, Richmond, Virginia 23219, USA and Nickel Producers Environmental Research Association (NiPERA), 2525 Meridian Parkway, Suite 240 Durham, North Carolina 27713, USA
| | - Michael A Pettiglio
- *North Carolina State University, College of Veterinary Medicine, 1060 William Moore Drive, Raleigh, North Carolina 27607, USA, Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Rm. 522, Providence, Rhode Island 02912, USA, Afton Chemical Corporation, 500 Spring Street, Richmond, Virginia 23219, USA and Nickel Producers Environmental Research Association (NiPERA), 2525 Meridian Parkway, Suite 240 Durham, North Carolina 27713, USA
| | - Athena M Keene
- *North Carolina State University, College of Veterinary Medicine, 1060 William Moore Drive, Raleigh, North Carolina 27607, USA, Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Rm. 522, Providence, Rhode Island 02912, USA, Afton Chemical Corporation, 500 Spring Street, Richmond, Virginia 23219, USA and Nickel Producers Environmental Research Association (NiPERA), 2525 Meridian Parkway, Suite 240 Durham, North Carolina 27713, USA
| | - Michael D Taylor
- *North Carolina State University, College of Veterinary Medicine, 1060 William Moore Drive, Raleigh, North Carolina 27607, USA, Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Rm. 522, Providence, Rhode Island 02912, USA, Afton Chemical Corporation, 500 Spring Street, Richmond, Virginia 23219, USA and Nickel Producers Environmental Research Association (NiPERA), 2525 Meridian Parkway, Suite 240 Durham, North Carolina 27713, USA
| | - David C Dorman
- *North Carolina State University, College of Veterinary Medicine, 1060 William Moore Drive, Raleigh, North Carolina 27607, USA, Department of Pathology and Laboratory Medicine, Brown University, 70 Ship Street, Rm. 522, Providence, Rhode Island 02912, USA, Afton Chemical Corporation, 500 Spring Street, Richmond, Virginia 23219, USA and Nickel Producers Environmental Research Association (NiPERA), 2525 Meridian Parkway, Suite 240 Durham, North Carolina 27713, USA
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Rahbar MH, Samms-Vaughan M, Dickerson AS, Loveland KA, Ardjomand-Hessabi M, Bressler J, Shakespeare-Pellington S, Grove ML, Pearson DA, Boerwinkle E. Blood manganese concentrations in Jamaican children with and without autism spectrum disorders. Environ Health 2014; 13:69. [PMID: 25149876 PMCID: PMC4237806 DOI: 10.1186/1476-069x-13-69] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 08/07/2014] [Indexed: 05/16/2023]
Abstract
BACKGROUND Manganese is an essential element for human health and development. Previous studies have shown neurotoxic effects in children exposed to higher levels of manganese. Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that impairs social interaction and communication. Several studies have hypothesized that ASD is caused through environmental exposures during crucial stages in brain development. We investigated the possible association between blood manganese concentrations (BMC) and ASD. We also identified factors associated with BMC in typically developing (TD) Jamaican children. METHODS We used data from 109 ASD cases with their 1:1 age- and sex-matched TD controls to compare mean BMC in Jamaican children (2-8 years of age) with and without ASD. We administered a pre-tested questionnaire to assess demographic and socioeconomic information, medical history, and potential exposure to manganese. Finally, we collected 2 mL of whole blood from each child for analysis of manganese levels. Using General Linear Models (GLM), we assessed the association between BMC and ASD status. Furthermore, we used two independent sample t-tests to identify factors associated with BMC in TD children. RESULTS In univariable GLM analysis, we found no significant association between BMC and ASD, (10.9 μg/L for cases vs. 10.5 μg/L for controls; P = 0.29). In a multivariable GLM adjusting for paternal age, parental education, place of child's birth (Kingston parish), consumption of root vegetables, cabbage, saltwater fish, and cakes/buns, there was still no significant association between BMC and ASD status, (11.5 μg/L for cases vs. 11.9 μg/L for controls; P = 0.48). Our findings also indicated TD children who ate fresh water fish had a higher BMC than children who did not (11.0 μg/L vs. 9.9 μg/L; P = 0.03) as younger TD children (i.e., 2 ≤ age ≤4), (12.0 μg/L vs. 10.2 μg/L; P = 0.01). CONCLUSIONS While these results cannot be used to assess early exposure at potentially more susceptible time period, our findings suggest that there is no significant association between manganese exposures and ASD case status in Jamaica. Our findings also indicate that BMC in Jamaican children resemble those of children in the developed world and are much lower than those in the developing countries.
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Affiliation(s)
- Mohammad H Rahbar
- Division of Epidemiology, Human Genetics, and Environmental Sciences (EHGES), University of Texas School of Public Health at Houston, Houston, Texas, USA
- Division of Clinical and Translational Sciences, Department of Internal Medicine, University of Texas Medical School at Houston, Houston, Texas 77030, USA
- Biostatistics/Epidemiology/Research Design (BERD) component, Center for Clinical and Translational Sciences (CCTS), University of Texas Health Science Center at Houston, UT Professional Building Suite 1100.05, 6410 Fannin Street, Houston, TX 77030, USA
| | - Maureen Samms-Vaughan
- Department of Child & Adolescent Health, The University of the West Indies (UWI), Mona Campus, Kingston, Jamaica
| | - Aisha S Dickerson
- Biostatistics/Epidemiology/Research Design (BERD) component, Center for Clinical and Translational Sciences (CCTS), University of Texas Health Science Center at Houston, UT Professional Building Suite 1100.05, 6410 Fannin Street, Houston, TX 77030, USA
| | - Katherine A Loveland
- Department of Psychiatry and Behavioral Sciences, University of Texas Medical School at Houston, Houston, Texas 77054, USA
| | - Manouchehr Ardjomand-Hessabi
- Biostatistics/Epidemiology/Research Design (BERD) component, Center for Clinical and Translational Sciences (CCTS), University of Texas Health Science Center at Houston, UT Professional Building Suite 1100.05, 6410 Fannin Street, Houston, TX 77030, USA
| | - Jan Bressler
- Human Genetics Center, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | | | - Megan L Grove
- Human Genetics Center, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
| | - Deborah A Pearson
- Department of Psychiatry and Behavioral Sciences, University of Texas Medical School at Houston, Houston, Texas 77054, USA
| | - Eric Boerwinkle
- Division of Epidemiology, Human Genetics, and Environmental Sciences (EHGES), University of Texas School of Public Health at Houston, Houston, Texas, USA
- Human Genetics Center, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA
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Hamadani JD, Tofail F, Nermell B, Gardner R, Shiraji S, Bottai M, Arifeen SE, Huda SN, Vahter M. Critical windows of exposure for arsenic-associated impairment of cognitive function in pre-school girls and boys: a population-based cohort study. Int J Epidemiol 2012; 40:1593-604. [PMID: 22158669 DOI: 10.1093/ije/dyr176] [Citation(s) in RCA: 192] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Exposure to arsenic through drinking water has been associated with impaired cognitive function in school-aged children in a few cross-sectional studies; however, there is little information on critical windows of exposure. METHODS We conducted a population-based longitudinal study in rural Bangladesh. We assessed the association of arsenic exposure, based on urinary arsenic (U-As; twice during pregnancy and twice in childhood), with the development of about 1700 children at 5 years of age using Wechsler Pre-school and Primary Scale of Intelligence [intelligence quotient (IQ)]. RESULTS Median maternal U-As in pregnancy was 80 µg/l (10-90 percentiles: 25-400 µg/l). Children's urine contained 35 (12-155) µg/l and 51 (20-238) µg/l at 1.5 and 5 years, respectively. Using multivariable-adjusted regression analyses, controlling for all potential confounders and loss to follow-up, we found that verbal IQ (VIQ) and full scale IQ (FSIQ) were negatively associated with (log) U-As in girls. The associations were consistent, but somewhat stronger with concurrent arsenic exposure [VIQ: B = -2.4, 95% confidence interval (CI) = -3.8 to -1.1; FSIQ: B = -1.4, 95% CI = -2.7 to -0.1, n = 817), compared with that at 1.5 years (VIQ: B = -0.85, 95% CI = -2.1 to 0.4; FSIQ: B = -0.74, 95% CI = -1.9 to 0.4, n = 902), late gestation (VIQ: B = -1.52, 95% CI = -2.6 to -0.4; FSIQ: B = -1.35, 95% CI = -2.4 to -0.3, n = 874) and early gestation (VIQ: B = -1.23, 95% CI = -2.4 to -0.06; FSIQ: B = -0.92, 95% CI = -2.0 to -0.2, n = 833). In boys, U-As showed consistently low and non-significant associations with all IQ measures. An effect size calculation indicated that 100 µg/l U-As was associated with a decrement of 1-3 points in both VIQ and FSIQ in girls. CONCLUSION We found adverse effects of arsenic exposure on IQ in girls, but not boys, at 5 years of age.
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Affiliation(s)
- J D Hamadani
- International Center for Diarrhoeal Disease Research, Dhaka, Bangladesh.
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