1
|
Huang H, Lv Y, Chen Q, Huang X, Qin J, Liu Y, Liao Q, Xing X, Chen L, Liu Q, Li S, Long Z, Wang Q, Chen W, Wei Q, Hou M, Hu Q, Xiao Y. Empirical analysis of lead neurotoxicity mode of action and its application in health risk assessment. ENVIRONMENTAL RESEARCH 2024; 251:118708. [PMID: 38493858 DOI: 10.1016/j.envres.2024.118708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 02/28/2024] [Accepted: 03/11/2024] [Indexed: 03/19/2024]
Abstract
The mode of action (MOA) framework is proposed to inform a biological link between chemical exposures and adverse health effects. Despite a significant increase in knowledge and awareness, the application of MOA in human health risk assessment (RA) remains limited. This study aims to discuss the adoption of MOA for health RA within a regulatory context, taking our previously proposed but not yet validated MOA for lead neurotoxicity as an example. We first conducted a quantitative weight of evidence (qWOE) assessment, which revealed that the MOA has a moderate confidence. Then, targeted bioassays were performed within an in vitro blood-brain barrier (BBB) model to quantitatively validate the scientific validity of key events (KEs) in terms of essentiality and concordance of empirical support (dose/temporal concordance), which increases confidence in utilizing the MOA for RA. Building upon the quantitative validation data, we further conducted benchmark dose (BMD) analysis to map dose-response relationships for the critical toxicity pathways, and the lower limit of BMD at a 5% response (BMDL5) was identified as the point of departure (POD) value for adverse health effects. Notably, perturbation of the Aryl Hydrocarbon Receptor (AHR) signaling pathway exhibited the lowest POD value, measured at 0.0062 μM. Considering bioavailability, we further calculated a provisional health-based guidance value (HBGV) for children's lead intake, determining it to be 2.56 μg/day. Finally, the health risk associated with the HBGV was assessed using the hazard quotient (HQ) approach, which indicated that the HBGV established in this study is a relative safe reference value for lead intake. In summary, our study described the procedure for utilizing MOA in health RA and set an example for MOA-based human health risk regulation.
Collapse
Affiliation(s)
- Hehai Huang
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China; Department of Occupational Health, Public Health Service Center, Bao'an District, Shenzhen, 518126, China
| | - Yanrong Lv
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Qingfei Chen
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xiaowei Huang
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, 530021, China
| | - Jingyao Qin
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Yan Liu
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Qilong Liao
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xiumei Xing
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Liping Chen
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Qing Liu
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Shuangqi Li
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Zihao Long
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Qing Wang
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Wen Chen
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Qing Wei
- Guangdong Provincial Key Laboratory of Food, Nutrition, and Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Mengjun Hou
- Guangdong Provincial Key Laboratory of Food, Nutrition, and Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Qiansheng Hu
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Yongmei Xiao
- Department of Occupational and Environmental Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China; Guangdong Provincial Key Laboratory of Food, Nutrition, and Health, School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China.
| |
Collapse
|
2
|
Püschel ML, Freise F, Carlson R, Tipold A, Nessler J. The Reibergram for immunoglobulin A in dogs: Evaluation of intrathecal IgA synthesis using a quotient graph in dogs with neurological diseases. Vet Med (Auckl) 2022; 37:191-203. [PMID: 36507577 PMCID: PMC9889711 DOI: 10.1111/jvim.16601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 11/18/2022] [Indexed: 12/14/2022]
Abstract
BACKGROUND Increased cerebrospinal fluid (CSF) protein concentration is a common finding in neurological diseases of dogs. Distinguishing between intrathecally-produced proteins and proteins that have passed the blood-CSF barrier because of barrier disruption facilitates diagnosis. Albumin is a microprotein mainly produced extrathecally that can be used as a reference marker for blood-CSF barrier dysfunction. OBJECTIVES Develop a quotient graph based on the CSF/serum quotient of albumin and immunoglobulin A (IgA; Reibergram) to visualize intrathecal IgA synthesis and blood-CSF barrier dysfunction. ANIMALS AND METHODS Retrospective single-center cohort study. A hyperbolic function was developed using data from 6 healthy Beagles and 38 dogs with neurological diseases in which an isolated blood-CSF barrier dysfunction was expected. The function was validated using data from 10 dogs with expected intrathecal IgA synthesis and was visualized as a quotient graph. Finally, the graph was used to evaluate data of 118 dogs with various neurological diseases. RESULTS Within the Reibergram, the function QLim IgA = 0.13 QAlb 2 + 11.9 · 10 - 6 - 1.01 · 10 - 3 describes the upper values of physiological IgA quotients. It detects diseases with expected intrathecal IgA synthesis with higher sensitivity (85%) and specificity (89%) than the IgA index. The upper value of the physiological albumin quotient is 2.22 and detects diseases with expected blood-CSF barrier dysfunction (sensitivity: 81%; specificity: 88%). CONCLUSION AND CLINICAL IMPORTANCE The canine Reibergram can detect blood-CSF barrier dysfunction and intrathecal IgA synthesis in the majority of cases. The graphical visualization simplifies data evaluation and makes it a feasible tool in routine CSF diagnostic testing.
Collapse
Affiliation(s)
- Mirja L. Püschel
- Department of Small Animal Medicine and SurgeryUniversity of Veterinary Medicine, FoundationHannoverGermany
| | - Fritjof Freise
- Institute for Biometry, Epidemiology, and Information Processing, University of Veterinary Medicine, FoundationHannoverGermany
| | - Regina Carlson
- Department of Small Animal Medicine and SurgeryUniversity of Veterinary Medicine, FoundationHannoverGermany
| | - Andrea Tipold
- Department of Small Animal Medicine and SurgeryUniversity of Veterinary Medicine, FoundationHannoverGermany
| | - Jasmin Nessler
- Department of Small Animal Medicine and SurgeryUniversity of Veterinary Medicine, FoundationHannoverGermany
| |
Collapse
|
3
|
Abstract
Ischemic brain edema, the accumulation of fluid within the brain parenchyma following stroke, is a predictable consequence of both ischemic and hemorrhagic strokes. Its development is the result of injury to both brain parenchyma and the blood vessels supplying the parenchyma. Ischemic stroke produces both cytotoxic (intracellular) edema, which develops when cells are damaged, and vasogenic (extracellular) edema, which arises from injury to structures essential to blood-brain barrier integrity. An understanding of the distinction between cytotoxic and vasogenic edema is essential in preventing secondary brain injury, since the treatments for the two entities differ. The development of new brain imaging technologies has advanced our understanding of brain edema. Both computed tomography (CT) and magnetic resonance imaging (MRI) can detect edema. Specific MRI sequences such as diffusion-weighted imaging can distinguish cytotoxic and vasogenic subtypes, and thereby detect ischemic cell injury within minutes of the onset of symptoms. Brain edema causes neurologic deterioration predominantly through its mass effect, which leads to distortion of the intracranial contents and impairment of both regional and global cerebral blood flow (CBF). Edema may also cause local tissue dysfunction. Management of the intracranial hypertension and tissue shifts caused by ischemic brain swelling is based on the fundamental relationship between pressure, flow, and resistance. Interventions are directed at preserving CBF and preventing secondary brain injury. Strategies include reducing intracranial blood volume with hypocapnia, reducing brain volume with osmotic agents, reducing cerebral metabolism with hypothermia and barbiturates, reducing resistance with rheologic agents, increasing blood pressure with vasoconstrictors, and expanding the cranial vault with decompressive surgery. All individual therapies must be used as part of a structured approach that involves frequent serial neurologic assessments, quantitative measures of pressure, flow, and resistance, and prespecified protocols for intervention.
Collapse
Affiliation(s)
- Jonathan Rosand
- Stroke Service, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Lee H. Schwamm
- Stroke Service, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
| |
Collapse
|
4
|
Abstract
Lead is a metal that has been implicated in toxic processes, which affect several organ systems in humans and other animals. The purpose of this study was to investigate the ultrastructural effects of lead on the brain of rats.Wistar Albino rats (180-200 g body weight) were divided into a controlled and lead acetate-exposed group. Rats received lead acetate at 500 ppm in their drinking water for 60 days. Both groups were fed with the same standard food, but lead acetate was added to the drinking water. During the experimental period, blood samples were drawn from the abdominal aorta of the anesthetised animals. At the end of exposure, body weight and blood lead levels were measured. The brain tissue samples were preapared and analysed by light and transmission electron microscopy. In the brain cortex, degeneration in some of the neuron cells, in the lumens of the blood vessels, dilation, hemorhagia and free floating erytrocytes were observed. Ultrastructural changes were revealed in the form of vacularisation of cell cytoplasm and degeneration in mitochondria, in the perinuclear cytoplasm, electron-dense inclusion bodies were detected, and dilation were in the endopasmic reticulum. Toxicology and Industrial Health 2006; 22: 419-422.
Collapse
Affiliation(s)
- Engin Deveci
- Department of Histology and Embryology, Dicle University Medical Faculty, Diyarbakir, Turkey.
| |
Collapse
|
5
|
Lassiter MG, Owens EO, Patel MM, Kirrane E, Madden M, Richmond-Bryant J, Hines EP, Davis JA, Vinikoor-Imler L, Dubois JJ. Cross-species coherence in effects and modes of action in support of causality determinations in the U.S. Environmental Protection Agency's Integrated Science Assessment for Lead. Toxicology 2015; 330:19-40. [PMID: 25637851 DOI: 10.1016/j.tox.2015.01.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 12/24/2014] [Accepted: 01/26/2015] [Indexed: 01/26/2023]
Abstract
The peer-reviewed literature on the health and ecological effects of lead (Pb) indicates common effects and underlying modes of action across multiple organisms for several endpoints. Based on such observations, the United States (U.S.) Environmental Protection Agency (EPA) applied a cross-species approach in the 2013 Integrated Science Assessment (ISA) for Lead for evaluating the causality of relationships between Pb exposure and specific endpoints that are shared by humans, laboratory animals, and ecological receptors (i.e., hematological effects, reproductive and developmental effects, and nervous system effects). Other effects of Pb (i.e., cardiovascular, renal, and inflammatory responses) are less commonly assessed in aquatic and terrestrial wildlife limiting the application of cross-species comparisons. Determinations of causality in ISAs are guided by a framework for classifying the weight of evidence across scientific disciplines and across related effects by considering aspects such as biological plausibility and coherence. As illustrated for effects of Pb where evidence across species exists, the integration of coherent effects and common underlying modes of action can serve as a means to substantiate conclusions regarding the causal nature of the health and ecological effects of environmental toxicants.
Collapse
Affiliation(s)
- Meredith Gooding Lassiter
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Elizabeth Oesterling Owens
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Molini M Patel
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Ellen Kirrane
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Meagan Madden
- Oak Ridge Institute for Science and Education Research Participation Program, National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Jennifer Richmond-Bryant
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Erin Pias Hines
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - J Allen Davis
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Lisa Vinikoor-Imler
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Jean-Jacques Dubois
- Southern Region Integrated Pest Management Center, North Carolina State University, 1730 Varsity Drive, Suite 110, Raleigh, NC 27606, USA.
| |
Collapse
|
6
|
Li M, Ma RN, Li LH, Qu YZ, Gao GD. Astragaloside IV reduces cerebral edema post-ischemia/reperfusion correlating the suppression of MMP-9 and AQP4. Eur J Pharmacol 2013; 715:189-95. [DOI: 10.1016/j.ejphar.2013.05.022] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 05/09/2013] [Accepted: 05/24/2013] [Indexed: 11/25/2022]
|
7
|
Walker I, Coleman MD. The blood-brain barrier: In vitro methods and toxicological applications. Toxicol In Vitro 2012; 9:191-204. [PMID: 20650079 DOI: 10.1016/0887-2333(94)00202-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/1994] [Indexed: 12/16/2022]
Abstract
The blood-brain barrier (BBB) is reviewed with reference to in vitro cell culture models and their use and potential use in toxicological studies. The structure, function and in vitro study of brain microvessel endothelial cells (BMEC) is briefly described, as well as the effects of a number of xenobiotics, such as solvents, metals, polycations and herbicides, on the viability and barrier function of the BBB model. The biotransformation of xenobiotics is increasingly thought to be responsible for many toxic reactions seen in living systems. Few studies have addressed the effects of the products of biotransformation on the integrity of the barrier model. Many of the specific human bioactivating enzymes, such as cytochrome P-450s, can now be conveniently studied in eukaryotic in vitro gene expression systems. The combination of such systems with a well characterized porcine BMEC culture model might be useful in the study of reactive metabolites on the BBB, in terms of changes in indices of functional and structural BMEC viability. The potential applications and the value of such an experimental approach are discussed.
Collapse
Affiliation(s)
- I Walker
- Pharmaceutical Sciences Institute, Aston University, Birmingham B4 7ET, UK
| | | |
Collapse
|
8
|
Ek CJ, Dziegielewska KM, Habgood MD, Saunders NR. Barriers in the developing brain and Neurotoxicology. Neurotoxicology 2011; 33:586-604. [PMID: 22198708 DOI: 10.1016/j.neuro.2011.12.009] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 12/11/2011] [Accepted: 12/11/2011] [Indexed: 01/16/2023]
Abstract
The brain develops and grows within a well-controlled internal environment that is provided by cellular exchange mechanisms in the interfaces between blood, cerebrospinal fluid and brain. These are generally referred to by the term "brain barriers": blood-brain barrier across the cerebral endothelial cells and blood-CSF barrier across the choroid plexus epithelial cells. An essential component of barrier mechanisms is the presence of tight junctions between the endothelial and epithelial cells of these interfaces. This review outlines historical evidence for the presence of effective barrier mechanisms in the embryo and newborn and provides an up to date description of recent morphological, biochemical and molecular data for the functional effectiveness of these barriers. Intercellular tight junctions between cerebral endothelial cells and between choroid plexus epithelial cells are functionally effective as soon as they differentiate. Many of the influx and efflux mechanisms are not only present from early in development, but the genes for some are expressed at much higher levels in the embryo than in the adult and there is physiological evidence that these transport systems are functionally more active in the developing brain. This substantial body of evidence supporting the concept of well developed barrier mechanisms in the developing brain is contrasted with the widespread belief amongst neurotoxicologists that "the" blood-brain barrier is immature or even absent in the embryo and newborn. A proper understanding of the functional capacity of the barrier mechanisms to restrict the entry of harmful substances or administered therapeutics into the developing brain is critical. This knowledge would assist the clinical management of pregnant mothers and newborn infants and development of protocols for evaluation of risks of drugs used in pregnancy and the neonatal period prior to their introduction into clinical practice.
Collapse
Affiliation(s)
- C Joakim Ek
- Department of Pharmacology, University of Melbourne, Parkville, Victoria 3010, Australia
| | | | | | | |
Collapse
|
9
|
Qu YZ, Li M, Zhao YL, Zhao ZW, Wei XY, Liu JP, Gao L, Gao GD. Astragaloside IV attenuates cerebral ischemia-reperfusion-induced increase in permeability of the blood-brain barrier in rats. Eur J Pharmacol 2009; 606:137-41. [PMID: 19374856 DOI: 10.1016/j.ejphar.2009.01.022] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 01/08/2009] [Accepted: 01/09/2009] [Indexed: 10/21/2022]
Abstract
Astragalus membranaceus is widely used to treat stroke and chronic debilitating diseases in China, but the mechanism has not been fully demonstrated to data. In the present study, we, using astragaloside IV, a purified extract from astragalus membranaceus, to a focal cerebral ischemia/reperfusion rat model, aimed to investigate the effect of astragaloside IV on the permeability of the blood-brain barrier since disruption of blood-brain barrier induced by ischemia/reperfusion leads to serious brain injuries. We found that astragaloside IV (10, 20 mg/kg) significantly attenuated the permeability of blood-brain barrier in comparison with vehicle group after ischemia/reperfusion assessed via Evans blue leakage (P<0.05). This was further confirmed by examination of blood-brain barrier permeability under the electron microscope, using lanthanum as a tracer of blood vessel permeability. Lanthanum was usually found within the blood vessel in sham group, rather than in perivascular tissues as shown in vehicle group. In drug groups, lanthanum stain was mainly restricted within the cerebral capillary, indicating the potential protective effect of astragaloside IV on the integrity of blood-brain barrier in ischemia/reperfusion rats. Furthermore, we found that expression of occludin and zonae occludens-1 (ZO-1), the tight junction proteins, was decreased in endothelial cells in vehicle group, which, however, could be reversed by astragaloside IV administration. We propose that regulation of tight junctional proteins in the endothelial cells may be one mechanism astragaloside IV-mediated in attribution to blood-brain barrier protection in the ischemia/reperfusion rats.
Collapse
Affiliation(s)
- You Zhi Qu
- Department of Neurosurgery, Tangdu Hospital and Institute for Functional Brain Disorders, Baqiao District, Xi'an, PR China
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Shi LZ, Zheng W. Early lead exposure increases the leakage of the blood-cerebrospinal fluid barrier, in vitro. Hum Exp Toxicol 2007; 26:159-67. [PMID: 17439918 PMCID: PMC3980856 DOI: 10.1177/0960327107070560] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The cell type constructing the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCB) is entirely different, ie, endothelia in BBB and epithelia in BCB. Nonetheless, both barriers share a common character--the tight junctions (TJ) between adjacent cells. This study investigated the consequence of lead (Pb) exposure on the tightness of BCB. In an in vitro BCB transwell model, using immortalized choroidal epithelial Z310 cells, we found that early exposure to Pb (prior to the formation of tight barrier) at 5 and 10 microM, significantly reduced the tightness of BCB, as evidenced by a 20% reduction in transepithelial electrical resistance (TEER) values (P <0.05), and >20% increase in the paracellular permeability of [(14)C]sucrose (P <0.05). Exposure to Pb after the formation of tight barrier, however, did not cause any detectable barrier dysfunction. RT-PCR and Western blot analyses on typical TJ proteins revealed that Pb exposure decreased both the mRNA and protein levels of claudin-1, with the membrane-bound claudin-1 more profoundly affected than cytosolic claudin-1. Pb exposure, however, had no significant effect on ZO1 and occludin. These data suggest that Pb exposure selectively alters the cellular level of claudin-1, which, in turn, reduces the tightness and augments the permeability of tight blood-CSF barrier. The immature barrier appears to be more vulnerable to Pb toxicity than the mature, well-developed, brain barrier, the fact possibly contributing to Pb-induced neurotoxicity among young children.
Collapse
Affiliation(s)
| | - Wei Zheng
- Correspondence: Wei Zheng, PhD, Professor of Health Sciences, Purdue University School of Health Sciences, 550 Stadium Mall Drive, CIVL-1163D, West Lafayette, IN 47907-2051, USA
| |
Collapse
|
11
|
Hirooka T, Fujiwara Y, Yamamoto C, Yasutake A, Kaji T. Methylmercury Retards the Repair of Wounded Monolayer of Human Brain Microvascular Endothelial Cells by Inhibiting Their Proliferation without Nonspecific Cell Damage. ACTA ACUST UNITED AC 2007. [DOI: 10.1248/jhs.53.450] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Takashi Hirooka
- Organization for Frontier Research in Preventive Pharmaceutical Sciences, Hokuriku University
| | - Yasuyuki Fujiwara
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Hokuriku University
| | - Chika Yamamoto
- Organization for Frontier Research in Preventive Pharmaceutical Sciences, Hokuriku University
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Hokuriku University
| | | | - Toshiyuki Kaji
- Organization for Frontier Research in Preventive Pharmaceutical Sciences, Hokuriku University
- Department of Environmental Health, Faculty of Pharmaceutical Sciences, Hokuriku University
| |
Collapse
|
12
|
Wang Q, Luo W, Zheng W, Liu Y, Xu H, Zheng G, Dai Z, Zhang W, Chen Y, Chen J. Iron supplement prevents lead-induced disruption of the blood-brain barrier during rat development. Toxicol Appl Pharmacol 2006; 219:33-41. [PMID: 17234227 PMCID: PMC3982216 DOI: 10.1016/j.taap.2006.11.035] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2006] [Revised: 11/06/2006] [Accepted: 11/08/2006] [Indexed: 10/23/2022]
Abstract
Children are known to be venerable to lead (Pb) toxicity. The blood-brain barrier (BBB) in immature brain is particularly vulnerable to Pb insults. This study was designed to test the hypothesis that Pb exposure damaged the integrity of the BBB in young animals and iron (Fe) supplement may prevent against Pb-induced BBB disruption. Male weanling Sprague-Dawley rats were divided into four groups. Three groups of rats were exposed to Pb in drinking water containing 342 microg Pb/mL as Pb acetate, among which two groups were concurrently administered by oral gavage once every other day with 7 mg Fe/kg and 14 mg Fe/kg as FeSO(4) solution as the low and high Fe treatment group, respectively, for 6 weeks. The control group received sodium acetate in drinking water. Pb exposure significantly increased Pb concentrations in blood by 6.6-folds (p<0.05) and brain tissues by 1.5-2.0-folds (p<0.05) as compared to controls. Under the electron microscope, Pb exposure in young animals caused an extensive extravascular staining of lanthanum nitrate in brain parenchyma, suggesting a leakage of cerebral vasculature. Western blot showed that Pb treatment led to 29-68% reduction (p<0.05) in the expression of occludin as compared to the controls. Fe supplement among Pb-exposed rats maintained the normal ultra-structure of the BBB and restored the expression of occludin to normal levels. Moreover, the low dose Fe supplement significantly reduced Pb levels in blood and brain tissues. These data suggest that Pb exposure disrupts the structure of the BBB in young animals. The increased BBB permeability may facilitate the accumulation of Pb. Fe supplement appears to protect the integrity of the BBB against Pb insults, a beneficial effect that may have significant clinical implications.
Collapse
Affiliation(s)
- Qiang Wang
- Department of Occupational and Environmental Health, Faculty of Military Preventive Medicine, Fourth Military Medical University, 17 Changlexi Street, Xi’an, 710032, China
| | - Wenjing Luo
- Department of Occupational and Environmental Health, Faculty of Military Preventive Medicine, Fourth Military Medical University, 17 Changlexi Street, Xi’an, 710032, China
| | - Wei Zheng
- School of Health Sciences, Purdue University, West Lafayette, IN, USA
| | - Yiping Liu
- Institute of Microbiology Epidemiology, Academy of Military Medical Siences, Beijing 100071, China
| | - Hui Xu
- Department of Occupational and Environmental Health, Faculty of Military Preventive Medicine, Fourth Military Medical University, 17 Changlexi Street, Xi’an, 710032, China
| | - Gang Zheng
- Department of Occupational and Environmental Health, Faculty of Military Preventive Medicine, Fourth Military Medical University, 17 Changlexi Street, Xi’an, 710032, China
| | - Zhongming Dai
- Department of Occupational and Environmental Health, Faculty of Military Preventive Medicine, Fourth Military Medical University, 17 Changlexi Street, Xi’an, 710032, China
| | - Wenbin Zhang
- Department of Occupational and Environmental Health, Faculty of Military Preventive Medicine, Fourth Military Medical University, 17 Changlexi Street, Xi’an, 710032, China
| | - Yaoming Chen
- Department of Occupational and Environmental Health, Faculty of Military Preventive Medicine, Fourth Military Medical University, 17 Changlexi Street, Xi’an, 710032, China
| | - Jingyuan Chen
- Department of Occupational and Environmental Health, Faculty of Military Preventive Medicine, Fourth Military Medical University, 17 Changlexi Street, Xi’an, 710032, China
- Corresponding author: Fax: +86 29 8474863. (J. Chen)
| |
Collapse
|
13
|
Struzynska L, Dabrowska-Bouta B, Koza K, Sulkowski G. Inflammation-Like Glial Response in Lead-Exposed Immature Rat Brain. Toxicol Sci 2006; 95:156-62. [PMID: 17047031 DOI: 10.1093/toxsci/kfl134] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Numerous studies on lead (Pb) neurotoxicity have indicated this metal to be a dangerous toxin, particularly during developmental stages of higher organisms. Astrocytes are responsible for sequestration of this metal in brain tissue. Activation of astroglia may often lead to loss of the buffering function and contribute to pathological processes. This phenomenon is accompanied by death of neuronal cells and may be connected with inflammatory events arising from the production of a wide range of cytokines and chemokines. The effects of prolonged exposure to Pb upon glial activation are examined in immature rats to investigate this potential proinflammatory effect. When analyzed at the protein level, glial activation is observed after Pb exposure, as reflected by the increased level of glial fibrillary acidic protein and S-100beta proteins in all parts of the brain examined. These changes are associated with elevation of proinflammatory cytokines. Production of interleukin (IL)-1beta and tumor necrosis factor-alpha is observed in hippocampus, and production of IL-6 is seen in forebrain. The expression of fractalkine is observed in both hippocampus and forebrain but inconsiderably in the cerebellum. In parallel with cytokine expression, signs of synaptic damage in hippocampus are seen after Pb exposure, as indicated by decreased levels of the axonal markers synapsin I and synaptophysin. Obtained results indicate chronic glial activation with coexisting inflammatory and neurodegenerative features as a new mechanism of Pb neurotoxicity in immature rat brain.
Collapse
Affiliation(s)
- Lidia Struzynska
- Department of Neurochemistry, Medical Research Centre, Laboratory of Pathoneurochemistry, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | | | | | | |
Collapse
|
14
|
Ruan S, Gu Z. Toxic Effects of Low Level Lead on the Blood‐Brain Barrier in Rats. J Occup Health 2006. [DOI: 10.1539/joh.41.39] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Su‐yun Ruan
- Shanghai Institute of Labour Hygiene and Occupational Diseases
| | - Zu‐wei Gu
- Shanghai Institute of Labour Hygiene and Occupational Diseases
| |
Collapse
|
15
|
Witt KA, Davis TP. CNS drug delivery: opioid peptides and the blood-brain barrier. AAPS JOURNAL 2006; 8:E76-88. [PMID: 16584136 PMCID: PMC2751425 DOI: 10.1208/aapsj080109] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Peptides are key regulators in cellular and intercellular physiological responses and possess enormous promise for the treatment of pathological conditions. Opioid peptide activity within the central nervous system (CNS) is of particular interest for the treatment of pain owing to the elevated potency of peptides and the centrally mediated actions of pain processes. Despite this potential, peptides have seen limited use as clinically viable drugs for the treatment of pain. Reasons for the limited use are primarily based in the physiochemical and biochemical nature of peptides. Numerous approaches have been devised in an attempt to improve peptide drug delivery to the brain, with variable results. This review describes different approaches to peptide design/modification and provides examples of the value of these strategies to CNS delivery of peptide drugs. The various modes of modification of therapeutic peptides may be amalgamated, creating more efficacious "hybrid" peptides, with synergistic delivery to the CNS. The ongoing development of these strategies provides promise that peptide drugs may be useful for the treatment of pain and other neurologically-based disease states in the future.
Collapse
Affiliation(s)
- Ken A. Witt
- />Pharmaceutical Sciences, School of Pharmacy, Southern Illinois University, Edwardsville, 200 University Park Drive, 62026 Edwardsville, IL. USA
| | - Thomas P. Davis
- />Department of Medical Pharmacology, College of Medicine, The University of Arizona, LSN 542, 1501 N. Campbell Avenue, P.O. Box 245050, 85724 Tucson, Arizona
| |
Collapse
|
16
|
Zheng W, Aschner M, Ghersi-Egea JF. Brain barrier systems: a new frontier in metal neurotoxicological research. Toxicol Appl Pharmacol 2003; 192:1-11. [PMID: 14554098 PMCID: PMC3982148 DOI: 10.1016/s0041-008x(03)00251-5] [Citation(s) in RCA: 326] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The concept of brain barriers or a brain barrier system embraces the blood-brain interface, referred to as the blood-brain barrier, and the blood-cerebrospinal fluid (CSF) interface, referred to as the blood-CSF barrier. These brain barriers protect the CNS against chemical insults, by different complementary mechanisms. Toxic metal molecules can either bypass these mechanisms or be sequestered in and therefore potentially deleterious to brain barriers. Supportive evidence suggests that damage to blood-brain interfaces can lead to chemical-induced neurotoxicities. This review article examines the unique structure, specialization, and function of the brain barrier system, with particular emphasis on its toxicological implications. Typical examples of metal transport and toxicity at the barriers, such as lead (Pb), mercury (Hg), iron (Fe), and manganese (Mn), are discussed in detail with a special focus on the relevance to their toxic neurological consequences. Based on these discussions, the emerging research needs, such as construction of the new concept of blood-brain regional barriers, understanding of chemical effect on aged or immature barriers, and elucidation of the susceptibility of tight junctions to toxicants, are identified and addressed in this newly evolving field of neurotoxicology. They represent both clear challenges and fruitful research domains not only in neurotoxicology, but also in neurophysiology and pharmacology.
Collapse
Affiliation(s)
- Wei Zheng
- School of Health Sciences, Purdue University, West Lafayette, IN 47907, USA.
| | | | | |
Collapse
|
17
|
Lidsky TI, Schneider JS. Lead neurotoxicity in children: basic mechanisms and clinical correlates. Brain 2003; 126:5-19. [PMID: 12477693 DOI: 10.1093/brain/awg014] [Citation(s) in RCA: 621] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Lead has been recognized as a poison for millennia and has been the focus of public health regulation in much of the developed world for the better part of the past century. The nature of regulation has evolved in response to increasing information provided by vigorous scientific investigation of lead's effects. In recognition of the particular sensitivity of the developing brain to lead's pernicious effects, much of this legislation has been addressed to the prevention of childhood lead poisoning. The present review discusses the current state of knowledge concerning the effects of lead on the cognitive development of children. Addressed are the reasons for the child's exquisite sensitivity, the behavioural effects of lead, how these effects are best measured, and the long-term outlook for the poisoned child. Of particular importance are the accumulating data suggesting that there are toxicological effects with behavioural concomitants at exceedingly low levels of exposure. In addition, there is also evidence that certain genetic and environmental factors can increase the detrimental effects of lead on neural development, thereby rendering certain children more vulnerable to lead neurotoxicity. The public health implications of these findings are discussed.
Collapse
Affiliation(s)
- Theodore I Lidsky
- Center for Trace Element Studies and Environmental Neurotoxicology, NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA.
| | | |
Collapse
|
18
|
Villeda-Hernández J, Barroso-Moguel R, Méndez-Armenta M, Nava-Ruíz C, Huerta-Romero R, Ríos C. Enhanced brain regional lipid peroxidation in developing rats exposed to low level lead acetate. Brain Res Bull 2001; 55:247-51. [PMID: 11470323 DOI: 10.1016/s0361-9230(01)00512-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Neurotoxicity associated with lead exposure may be the result of a series of small perturbations in brain metabolism, and, in particular, of oxidative stress. Some studies have suggested a lead-induced enhancement on lipid peroxidation as a possible mechanism for some toxic effects of lead. However, there are no reports about the association between lipid peroxidation enhancement and brain lead content. In this study, we determined the concentration of lead and the formation of lipid fluorescence products in the blood, as well as in the parietal cortex, striatum, hippocampus, thalamus, and cerebellum of rats exposed prenatally and postnatally to variable concentrations of lead acetate through drinking water. Pregnant Wistar rats were intoxicated throughout gestation with solutions containing either 320 or 160 ppm of lead. The pups were treated after birth in the same way until 45 days of age. Control animals received deionized water for the same period of time. The developing rats were sacrificed at postnatal day 45 and lead level was assessed biochemically in the blood and different brain regions. Results showed that blood lead levels were increased in a dose-dependent manner. In the brain, lead accumulated preferentially in the parietal cortex, striatum, and thalamus as compared to the control group, while lipid fluorescence products were significantly increased in the striatum, thalamus, and hippocampus of the treated animals. These data suggest that in the brain of rats exposed to lead acetate, lead produces a neurotoxic effect with a complex correlation with both lead regional content and lipid peroxidation.
Collapse
Affiliation(s)
- J Villeda-Hernández
- Laboratorio de Neuromorfología Celular, Instituto Nacional de Neurología y Neurocirugía "M. Velasco Suárez", Mexico City, Mexico
| | | | | | | | | | | |
Collapse
|
19
|
|
20
|
Struzyńska L, Walski M, Gadamski R, Dabrowska-Bouta B, Rafałowska U. Lead-induced abnormalities in blood-brain barrier permeability in experimental chronic toxicity. MOLECULAR AND CHEMICAL NEUROPATHOLOGY 1997; 31:207-24. [PMID: 9336764 DOI: 10.1007/bf02815125] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The aim of this paper was to determine whether prolonged drinking of lead acetate-containing water by adult rats, which imitates environmental exposure to lead (Pb), affects some morphological and biochemical properties of rat brain microvessels. We noted a significant increase of lead level in capillaries and synaptosomes obtained from brains of rats under chronic toxicity conditions. Intravenously injected horseradish peroxidase (HRP) was used to evaluate the functional state of the blood-brain barrier (BBB). The results indicate that, systematically administered at low doses, lead induces BBB dysfunction. The changes, revealed in light microscopy and confirmed by electron microscopic studies, are typical for "leaky" microvessels, reported for variety of neuropathological conditions associated with BBB damage. Enhanced pinocytotic activity of the endothelial cells and the opening of interendothelial tight junctions, together with enormous phagocytizing action of the pericytes, are the most characteristic ultrastructural features noted. The presence of specific type of perivascular cells containing droplets of lipids in the cytoplasm, together with changes in phospholipid profile in brain capillaries, suggest that altered lipid composition of membranes may, at least in part, be responsible for changes in observed membrane permeability.
Collapse
Affiliation(s)
- L Struzyńska
- Department of Neurochemistry, Polish Academy of Sciences, Warsaw, Poland
| | | | | | | | | |
Collapse
|
21
|
Boivin MJ, Giordani B. A risk evaluation of the neuropsychological effects of childhood lead toxicity. Dev Neuropsychol 1995. [DOI: 10.1080/87565649509540611] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
22
|
Lead and Neuropsychological Function in Children: Progress and Problems in Establishing Brain-Behavior Relationships. ADVANCES IN CHILD NEUROPSYCHOLOGY 1995. [DOI: 10.1007/978-1-4612-4178-2_2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
23
|
Laterra J, Bressler JP, Indurti RR, Belloni-Olivi L, Goldstein GW. Inhibition of astroglia-induced endothelial differentiation by inorganic lead: a role for protein kinase C. Proc Natl Acad Sci U S A 1992; 89:10748-52. [PMID: 1438272 PMCID: PMC50419 DOI: 10.1073/pnas.89.22.10748] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Microvascular endothelial function in developing brain is particularly sensitive to lead toxicity, and it has been hypothesized that this results from the modulation of protein kinase C (PKC) by lead. We examined the effects of inorganic lead on an in vitro model of central nervous system endothelial differentiation in which astroglial cells induce central nervous system endothelial cells to form capillary-like structures. Capillary-like structure formation within C6 astroglial-endothelial cocultures was inhibited by lead acetate with 50% maximal inhibition at 0.5 microM total lead. Inhibition was independent of effects on cell viability or growth. Under conditions that inhibited capillary-like structure formation, we found that lead increased membrane-associated PKC in both C6 astroglial and endothelial cells. Prolonged exposure of C6 cells to 5 microM lead for up to 16 h resulted in a time-dependent increase in membranous PKC as determined by immunoblot analysis. Membranous PKC increased after 5-h exposures to as little as 50 nM lead and was maximal at approximately 1 microM. Phorbol esters were used to determine whether PKC modulation was causally related to the inhibition of endothelial differentiation by lead. Phorbol 12-myristate 13-acetate (10 nM) inhibited capillary-like structure formation by 65 +/- 5%, whereas 4 alpha-phorbol 12,13-didecanoate was without effect. These findings suggest that inorganic lead induces cerebral microvessel dysfunction by interfering with PKC modulation in microvascular endothelial or perivascular astroglial cells.
Collapse
Affiliation(s)
- J Laterra
- Kennedy Krieger Research Institute, Johns Hopkins Medical Institutions, Baltimore, MD 21205
| | | | | | | | | |
Collapse
|
24
|
Lindh U, Conradi NG, Sourander P. Distribution of lead in the cerebellum of suckling rats following low and high dose lead exposure. A micro-PIXE analysis. Acta Neuropathol 1989; 79:149-53. [PMID: 2596264 DOI: 10.1007/bf00294372] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The distribution of lead in the cerebellum of suckling Sprague-Dawley rats was examined using a nuclear microprobe for elemental mapping of tissue sections (particle-induced X-ray emission, 3-microns beam of 2.5 MeV protons; micro-PIXE). The rats were injected intraperitoneally with a lead-containing vehicle or vehicle only from ages 1 to 14 days. The calculated doses were 7.8 (low-dose) and 15.6 (high-dose) micrograms lead/g body weight. The rats were killed at 20 days of age. The vascular system was rinsed quickly with 0.15 M ammonium acetate to obtain determinations of intra-parenchymal lead with minimal influence of lead bound to erythrocytes and plasma proteins. Brains were frozen in propane/propylene in liquid nitrogen. Cryostat sections, 15 microns thick, were air dried on formvar coats that covered a hole, 15 mm in diameter, in a plastic disc, and were used for lead analysis by micro-PIXE. Very low concentrations of lead were found in the brain of controls. Lead levels in homogenates from cerebrum and cerebellum measured by atomic absorption spectrometry (AAS) were: low-dose 1.2-2.2 micrograms/g wet weight and high-dose 1.4-2.4 micrograms/g wet weight. The lead levels measured with the micro-PIXE method were in good agreement with the levels found with AAS. Lead was present in the cerebellar white matter in two to three times higher amounts than in the cortical grey (low-dose white matter 11-18 micrograms/g dry weight, grey matter 2.0-5.5 micrograms/g dry weight). This was true for both low and high dose exposed rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- U Lindh
- Department of Radiation Sciences, University of Uppsala, Sweden
| | | | | |
Collapse
|
25
|
Moorhouse SR, Carden S, Drewitt PN, Eley BP, Hargreaves RJ, Pelling D. The effect of chronic low level lead exposure on blood-brain barrier function in the developing rat. Biochem Pharmacol 1988; 37:4539-47. [PMID: 3144282 DOI: 10.1016/0006-2952(88)90670-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Blood-brain barrier (BBB) function was assessed in 19-21-day-old rats exposed to low level lead from birth. Newborn rats received lead via milk from lactating dams given drinking water containing 0.1% lead acetate [Pb(Ac)2]. The treatment regime produced lead levels in the neonates within the range 20-80 micrograms dl-1 blood, without affecting growth. Cerebrovascular permeability (PS-product) to the diffusion-limited solute mannitol was unchanged in six regions of the cerebral hemisphere, the cerebellum and the brainstem, suggesting that barrier integrity was not affected by the low dose lead treatment. Regional cerebrovascular permeability to nutrient tracers representing seven BBB transport classes was not impaired by lead treatment. However, the PS estimates for the amino acids lysine and histidine and for thiamine were greater than control in some regions of the cerebral hemisphere. These alterations in nutrient supply to the brain may reflect altered substrate utilization associated with repair processes or delayed maturation of the CNS.
Collapse
Affiliation(s)
- S R Moorhouse
- Department of Pharmacology, British Industrial Biological Research Association, Carshalton, Surrey, U.K
| | | | | | | | | | | |
Collapse
|
26
|
Salahuddin TS, Kalimo H, Johansson BB, Olsson Y. Observations on exsudation of fibronectin, fibrinogen and albumin in the brain after carotid infusion of hyperosmolar solutions. An immunohistochemical study in the rat indicating longlasting changes in the brain microenvironment and multifocal nerve cell injuries. Acta Neuropathol 1988; 76:1-10. [PMID: 3293343 DOI: 10.1007/bf00687674] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
An immunohistochemical study was carried out on rat brain to determine if a transient opening of the blood-brain barrier (BBB), leading to extravasation of serum albumin, is also associated with exudation and cellular uptake of fibronectin and fibrinogen. Both of them might exert important biological effects provided that they pass the BBB and come into contact with cells of the brain parenchyma. Hyperosmolar solutions of urea or mannitol were infused in the carotid artery for 30 s to open the BBB and the animals were killed at various time intervals thereafter. Formaldehyde-fixed, paraffin-embedded material was used for immunohistochemical demonstration of extravasated proteins by an avidin-biotin peroxidase technique. Multifocal, often confluent areas of widely different sizes with signs of albumin extravasation were observed both in the grey and the white matter of the cerebral hemispheres exposed to the hyperosmolar solutions. Much less pronounced changes were observed in rats given an intracarotid saline infusion alone. Immunoreactive material indicating extravasation of fibronectin and fibrinogen was present in the infused cerebral hemispheres but albumin immunoreactivity was much more widespread. Reaction product was observed in vascular walls, presumably in extracellular spaces and in nerve cells. Immunoreactivity in the perikaryon of neurons formed different patterns in various cells. A granular type most probably represents accumulation of the proteins in lysosomal organelles after pinocytotic uptake into the neuron. The second so-called diffuse variety is presumably the result of a severe nerve cell injury with an uncontrolled leakage of proteins into the cytoplasm. Our results indicate that vascular walls, extracellular spaces, glial cells and neurons will be exposed to extravasated fibronectin and fibrinogen as well as to albumin and that antigenic sites in such compounds remain for a long period after the BBB opening. In addition, there are indications that carotid infusions of hyperosmolar solutions may cause nerve cell injuries in regions with BBB opening. These findings have obvious clinical and experimental significance.
Collapse
Affiliation(s)
- T S Salahuddin
- Laboratory of Neuropathology, University Hospital, Uppsala, Sweden
| | | | | | | |
Collapse
|
27
|
Kerlero de Rosbo N, Jago MV, Carnegie PR, Bernard CC. Correlation of the onset of experimental autoimmune encephalomyelitis-like clinical signs with oedema of the spinal cord in tunicamycin-poisoned rats. J Neurol Sci 1987; 78:281-94. [PMID: 2438387 DOI: 10.1016/0022-510x(87)90042-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The neurological signs induced by injection of tunicamycin are, in young adult rats, virtually identical to those typical of acute experimental autoimmune encephalomyelitis (EAE). Vasogenic exudation, of which the occurrence in the spinal cord of EAE rats has been shown to coincide with the onset of clinical signs, was investigated by quantitative electroimmunoblotting of central nervous system (CNS) tissue at various times following tunicamycin injection of young adult rats. Highly elevated levels of extravasated plasma proteins were observed in the spinal cord from 48 h after injection and, as in EAE rats, these increases coincided with the onset of neurological impairment. At 72 h post-injection, significant increases were also found in the brain of affected animals, albeit at much reduced levels. This is in contrast to previously reported findings in nursling rats where oedema was shown to be predominantly located in the brain. Quantitative electroimmunoblotting for myelin basic protein (MBP) in the CNS of tunicamycin-treated young adult rats indicated that, as in acute EAE, no extensive demyelination had occurred. These data provided further evidence that in both neurological diseases, vasogenic oedema of the spinal cord may be causally related to the appearance of neurological signs and suggested that its differential localization in the CNS may lead to differential neurological impairment.
Collapse
|
28
|
Sundström R, Karlsson B. Myelin basic protein in brains of rats with low dose lead encephalopathy. Arch Toxicol 1987; 59:341-5. [PMID: 2437882 DOI: 10.1007/bf00295087] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Postnatal exposure of rats to lead has been shown previously to cause CNS hypo-myelination. Since rats intoxicated with lead often show retarded growth, the superimposed malnutrition, which as such can cause hypomyelination, may contribute to myelin deficit. In the present study control rats and lead exposed rats which did not have any retardation of growth were examined by radioimmunological assay of myelin basic protein (MBP) of homogenates of cerebrum and cerebellum at 30, 60 and 120 days of age. Lead was administered on postnatal days 1-15 by daily intraperitoneal injections of 10 mg lead nitrate/kg body weight. This lead dose results in light microscopically discernible hemorrhagic encephalopathy in the cerebellum of 15-day old rats, but does not induce growth retardation (Sundström et al. 1983). The controls were injected with vehicle only. The amount of lead in the blood and brain homogenates of lead-exposed and control rats 15-200 days old was estimated by atomic absorption spectrophotometry. Significant differences between the lead-exposed and control rats were not found in the cerebral or cerebellar content of MBP. Considering the results of previous investigations, the findings do not exclude a hypo-myelinating effect of lead, but they suggest that exposure to lead without concomitant malnutrition does not cause hypo-myelination in the cerebrum and cerebellum of the developing rat.
Collapse
|
29
|
Sundström R, Kalimo H. Extracellular edema and glial response to it in the cerebellum of suckling rats with low-dose lead encephalopathy. An electron microscopic and immunohistochemical study. Acta Neuropathol 1987; 75:116-22. [PMID: 3434220 DOI: 10.1007/bf00687071] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Newborn rats were exposed to daily intraperitoneal injections of 10 mg lead nitrate per kg body weight for the first 15 postnatal days. The growth and mortality of the lead-exposed animals did not differ from their control litter-mates, injected with vehicle only. In our previous studies, focal hemorrhages and spongy areas as well as breakdown of blood-brain barrier to plasma proteins were shown by light microscopy in the cerebellar parenchyma of 15-day-old rats exposed to this dose. In spite of these signs of edema, measurements of brain tissue specific gravity did not show increased water content. In the present investigation we examined the ultrastructure of the brain lesions in these rats with low-dose lead encephalopathy, focusing on signs of edema, and evaluated astroglial reaction by immunocytochemical staining for glial fibrillary acidic protein (GFAP). The electron microscopic findings were compatible with extracellular edema in the cerebellum of 15-day-old lead exposed rats. The number of GFAP-positive cell bodies in the gray substance of the cerebellar cortex was increased in the 15-day-old lead-exposed rats as compared with the controls of the same age, a finding which is presumably related to the leakage of plasma proteins. Both these findings were lacking at 20 days of age, suggesting reversibility of the lead-induced changes.
Collapse
Affiliation(s)
- R Sundström
- Department of Pathology, University of Göteborg, Sweden
| | | |
Collapse
|