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Podlasz P, Wasowicz K. Effect of partial hysterectomy on the neurons of the paracervical ganglion (PCG) of the pig. PLoS One 2021; 16:e0245974. [PMID: 33497400 PMCID: PMC7837480 DOI: 10.1371/journal.pone.0245974] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 01/11/2021] [Indexed: 12/14/2022] Open
Abstract
Autonomic neurons innervating uterine horn is probably the only nerve cell population capable of periodical physiological degeneration and regeneration. One of the main sources of innervation of the uterus is paracervical ganglion (PCG). PCG is a unique structure of the autonomic nervous system. It contains components of both the sympathetic and parasympathetic nervous system. The present study examines the response of neurons of PCG innervating uterine horn to axotomy caused by partial hysterectomy in the domestic pig animal model. The study was performed using a neuronal retrograde tracing and double immunofluorescent staining for tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DβH), choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), neuronal nictric oxide synthase (nNOS), galanin, neuropeptide Y (NPY), vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating peptide (PACAP), somatostatin and substance P (SP). Our study showed that virtually all neurons of the porcine PCG innervating uterine horn are adrenergic and we did not confirm that PCG is the source of cholinergic fibers innervating uterine horn of the pig. After axotomy there was a decrease in expression of catecholamine-synthesizing enzymes (TH, DβH) and a strong increase in the galanin expression. The increase of the number of NPY-IR neurons in the ganglia after axotomy was observed. There were no changes in the expression of other studied substances in the PCG neurons innervating the uterine horn, what was often found in rodents studies. This indicates that neurons can respond to damage in a species-specific way.
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Affiliation(s)
- Piotr Podlasz
- Department of Pathophysiology, Forensic Veterinary Medicine and Administration, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
- * E-mail:
| | - Krzysztof Wasowicz
- Department of Pathophysiology, Forensic Veterinary Medicine and Administration, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
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A glycolytic shift in Schwann cells supports injured axons. Nat Neurosci 2020; 23:1215-1228. [PMID: 32807950 DOI: 10.1038/s41593-020-0689-4] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 07/07/2020] [Indexed: 01/09/2023]
Abstract
Axon degeneration is a hallmark of many neurodegenerative disorders. The current assumption is that the decision of injured axons to degenerate is cell-autonomously regulated. Here we show that Schwann cells (SCs), the glia of the peripheral nervous system, protect injured axons by virtue of a dramatic glycolytic upregulation that arises in SCs as an inherent adaptation to axon injury. This glycolytic response, paired with enhanced axon-glia metabolic coupling, supports the survival of axons. The glycolytic shift in SCs is largely driven by the metabolic signaling hub, mammalian target of rapamycin complex 1, and the downstream transcription factors hypoxia-inducible factor 1-alpha and c-Myc, which together promote glycolytic gene expression. The manipulation of glial glycolytic activity through this pathway enabled us to accelerate or delay the degeneration of perturbed axons in acute and subacute rodent axon degeneration models. Thus, we demonstrate a non-cell-autonomous metabolic mechanism that controls the fate of injured axons.
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Nukada H, Baba M, Ogasawara S, McMorran D, Yagihashi S. Neuropathy in the spontaneously hypertensive rat: An electrophysiological and histological study. Muscle Nerve 2016; 54:756-62. [PMID: 26970072 DOI: 10.1002/mus.25098] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 02/24/2016] [Accepted: 03/03/2016] [Indexed: 02/04/2023]
Abstract
INTRODUCTION Hypertension is identified as a risk factor for development of polyneuropathy. In this study we examined nerve conduction and morphological alteration of peripheral nerves in spontaneously hypertensive rats (SHR). METHODS Motor nerve conduction velocity (MNCV) in the sciatic-tibial nerve and sensory nerve conduction velocity (SNCV) in the sural nerve were measured. Pathological investigations included spinal cord, dorsal root ganglion, and hindlimb nerves in SHR and Wistar-Kyoto rats (WKY) aged 4-64 weeks. RESULTS Blood pressure was significantly higher in SHR than WKY animals at 4 weeks and elevated further with aging. MNCV and SNCV were significantly slower in SHR compared with WKY after age 24 weeks. Prominent morphological changes in SHR nerves included axonal atrophy and myelin splitting. SHR also had endoneurial microangiopathy with reduplication of basement membrane. CONCLUSIONS SHR showed slowed nerve conduction velocity and pathological abnormalities of hindlimb nerves. Sustained severe hypertension may cause axonal atrophy and endoneurial microangiopathy. Muscle Nerve 54: 756-762, 2016.
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Affiliation(s)
- Hitoshi Nukada
- The Nukada Institute for Medical & Biological Research, 5-18 Inage-machi, Inage-ku, Chiba, 263-0035, Japan. .,Department of Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand.
| | - Masayuki Baba
- Department of Neurology, Aomori Prefectural Central Hospital, Aomori, Japan
| | - Saori Ogasawara
- Department of Pathology and Molecular Medicine, Hirosaki University, Hirosaki, Japan
| | - Denise McMorran
- Department of Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Soroku Yagihashi
- Department of Pathology and Molecular Medicine, Hirosaki University, Hirosaki, Japan
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Abstract
The mechanism underlying acrylamide-induced neurotoxicity remains controversial. Previous studies have focused on acrylamide-induced toxicity in adult rodents, but neurotoxicity in weaning rats has not been investigated. To explore the neurotoxic effect of acrylamide on the developing brain, weaning rats were gavaged with 0, 5, 15, and 30 mg/kg acrylamide for 4 consecutive weeks. No obvious neurotoxicity was observed in weaning rats in the low-dose acrylamide group (5 mg/kg). However, rats from the moderate- and high-dose acrylamide groups (15 and 30 mg/kg) had an abnormal gait. Furthermore, biochemical tests in these rats demonstrated that glutamate concentration was significantly reduced, and γ-aminobutyric acid content was significantly increased and was dependent on acrylamide dose. Immunohistochemical staining showed that in the cerebral cortex, γ-aminobutyric acid, glutamic acid decarboxylase and glial fibrillary acidic protein expression increased remarkably in the moderate- and high-dose acrylamide groups. These results indicate that in weaning rats, acrylamide is positively associated with neurotoxicity in a dose-dependent manner, which may correlate with upregulation of γ-aminobutyric acid and subsequent neuronal degeneration after the initial acrylamide exposure.
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Affiliation(s)
- Su-Min Tian
- School of Basic Medicine, Guangdong Pharmaceutical University, Guangzhou, Guangdong Province, China
| | - Yu-Xin Ma
- School of Basic Medicine, Guangdong Pharmaceutical University, Guangzhou, Guangdong Province, China
| | - Jing Shi
- Xiqiao People's Hospital, Foshan, Guangdong Province, China
| | - Ting-Ye Lou
- Clinical Laboratory of First Affiliated Hospital, Xinxiang Medical University, Xinxiang, Henan Province, China
| | - Shuai-Shuai Liu
- Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
| | - Guo-Ying Li
- School of Basic Medicine, Guangdong Pharmaceutical University, Guangzhou, Guangdong Province, China
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5
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Abstract
Toxic neuropathy, although rare, is an important consideration in the setting of a known or suspected toxic exposure in the workplace or other environment. This chapter discusses the clinical and electrodiagnostic evaluation of peripheral neuropathies, highlighting findings that direct further workup and may point to specific toxins as etiology. The difficulty of establishing causality of a toxin in relation to peripheral neuropathy is discussed; guidelines for establishing causality are presented. Examples of common industrial toxins are listed, including their typical industrial uses and their mechanisms of action in producing neuropathy. Characteristic clinical presentations of specific toxic neuropathies are highlighted with selected case studies.
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Affiliation(s)
- Ann A Little
- Department of Neurology, University of Michigan Health System, Ann Arbor, MI, USA
| | - James W Albers
- Department of Neurology, University of Michigan Health System, Ann Arbor, MI, USA.
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Kaufmann W, Bolon B, Bradley A, Butt M, Czasch S, Garman RH, George C, Gröters S, Krinke G, Little P, McKay J, Narama I, Rao D, Shibutani M, Sills R. Proliferative and nonproliferative lesions of the rat and mouse central and peripheral nervous systems. Toxicol Pathol 2012; 40:87S-157S. [PMID: 22637737 DOI: 10.1177/0192623312439125] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Harmonization of diagnostic nomenclature used in the pathology analysis of tissues from rodent toxicity studies will enhance the comparability and consistency of data sets from different laboratories worldwide. The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of four major societies of toxicologic pathology to develop a globally recognized nomenclature for proliferative and nonproliferative lesions in rodents. This article recommends standardized terms for classifying changes observed in tissues of the mouse and rat central (CNS) and peripheral (PNS) nervous systems. Sources of material include academic, government, and industrial histopathology databases from around the world. Covered lesions include frequent, spontaneous, and aging-related changes as well as principal toxicant-induced findings. Common artifacts that might be confused with genuine lesions are also illustrated. The neural nomenclature presented in this document is also available electronically on the Internet at the goRENI website (http://www.goreni.org/).
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Nielson JL, Sears-Kraxberger I, Strong MK, Wong JK, Willenberg R, Steward O. Unexpected survival of neurons of origin of the pyramidal tract after spinal cord injury. J Neurosci 2010; 30:11516-28. [PMID: 20739574 PMCID: PMC2941508 DOI: 10.1523/jneurosci.1433-10.2010] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 07/02/2010] [Accepted: 07/08/2010] [Indexed: 11/21/2022] Open
Abstract
There is continuing controversy about whether the cells of origin of the corticospinal tract (CST) undergo retrograde cell death after spinal cord injury (SCI). All previous attempts to assess this have used imaging and/or histological techniques to assess upper motoneurons in the cerebral cortex. Here, we address the question in a novel way by assessing Wallerian degeneration and axon numbers in the medullary pyramid of Sprague Dawley rats after both acute SCI, either at cervical level 5 (C5) or thoracic level 9 (T9), and chronic SCI at T9. Our findings demonstrate that only a fraction of a percentage of the total axons in the medullary pyramid exhibit any sign of degeneration at any time after SCI--no more so than in uninjured control rats. Moreover, design-based counts of myelinated axons revealed no decrease in axon number in the medullary pyramid after SCI, regardless of injury level, severity, or time after injury. Spinal cord-injured rats had fewer myelinated axons in the medullary pyramid at 1 year after injury than aged matched controls, suggesting that injury may affect ongoing myelination of axons during aging. We conclude that SCI does not cause death of the CST cell bodies in the cortex; therefore, therapeutic strategies aimed at promoting axon regeneration of the CST in the spinal cord do not require a separate intervention to prevent retrograde degeneration of upper motoneurons in the cortex.
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Affiliation(s)
| | | | | | - Jamie K. Wong
- Reeve–Irvine Research Center
- Neurobiology and Behavior, and
| | - Rafer Willenberg
- Reeve–Irvine Research Center
- Departments of Anatomy and Neurobiology
| | - Oswald Steward
- Reeve–Irvine Research Center
- Departments of Anatomy and Neurobiology
- Neurobiology and Behavior, and
- Neurosurgery, University of California, Irvine, Irvine, California 92697
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Schaumburg HH, Zotova E, Raine CS, Tar M, Arezzo J. The rat caudal nerves: a model for experimental neuropathies. J Peripher Nerv Syst 2010; 15:128-39. [PMID: 20626776 DOI: 10.1111/j.1529-8027.2010.00262.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study provides a detailed investigation of the anatomy of the rat caudal nerve along its entire length, as well as correlated nerve conduction measures in both large and small diameter axons. It determines that rodent caudal nerves provide a simple, sensitive experimental model for evaluation of the pathophysiology of degeneration, recovery, and prevention of length-dependent distal axonopathy. After first defining the normal anatomy and electrophysiology of the rat caudal nerves, acrylamide monomer, a reliable axonal toxin, was administered at different doses for escalating time periods. Serial electrophysiological recordings were obtained, during intoxication, from multiple sites along caudal and distal sciatic nerves. Multiple sections of the caudal and sciatic nerves were examined with light and electron microscopy. The normal distribution of conduction velocities was determined and acrylamide-induced time- and dose-related slowing of velocities at the vulnerable ultraterminal region was documented. Degenerative morphological changes in the distal regions of the caudal nerves appeared well before changes in the distal sciatic nerves. Our study has shown that (1) rat caudal nerves have a complex neural structure that varies along a distal-to-proximal gradient and (2) correlative assessment of both morphology and electrophysiology of rat caudal nerves is easily achieved and provides a highly sensitive index of the onset and progression of the length-dependent distal axonopathy.
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Affiliation(s)
- Herbert H Schaumburg
- Department of Neurology, Albert Einstein College of Medicine, Bronx, NY 10461-1602, USA.
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Bowyer JF, Latendresse JR, Delongchamp RR, Warbritton AR, Thomas M, Divine B, Doerge DR. The mRNA expression and histological integrity in rat forebrain motor and sensory regions are minimally affected by acrylamide exposure through drinking water. Toxicol Appl Pharmacol 2009; 240:401-11. [DOI: 10.1016/j.taap.2009.07.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 07/27/2009] [Accepted: 07/30/2009] [Indexed: 02/06/2023]
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10
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Yu S, Son F, Yu J, Zhao X, Yu L, Li G, Xie K. Acrylamide alters cytoskeletal protein level in rat sciatic nerves. Neurochem Res 2006; 31:1197-204. [PMID: 17043767 DOI: 10.1007/s11064-006-9176-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2006] [Accepted: 09/15/2006] [Indexed: 11/24/2022]
Abstract
Occupational exposure and experimental intoxication with acrylamide (ACR) produce neuropathy characterized by nerve degeneration. To investigate the mechanism of ACR-induced neuropathy, male adult Wistar rats were given ACR (20, 40 mg/kg i.p. 3 days/week) for 8 weeks. Sciatic nerves were Triton-extracted and centrifuged at a high speed (100,000 x g) to yield pellet and supernatant fractions. The contents of six cytoskeletal proteins (NF-L, NF-M, NF-H, alpha-tubulin, beta-tubulin, and beta-actin) in both fractions were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Results showed that the three neurofilament (NF) subunits (NF-L, NF-M, NF-H) in both the pellet and the supernatant fraction decreased significantly (P < 0.01) in the high-dosing group, except for NF-M in the pellet. alpha-tubulin, beta-tubulin, and beta-actin increased significantly in the supernatant (P < 0.01), whereas both alpha-tubulin and beta-tubulin decreased significantly in the pellet (P < 0.01). However, beta-actin was not altered significantly in the sciatic nerves pellet. These findings suggest that ACR altered the cytoskeletal protein level in sciatic nerve, which may be one of the molecular mechanisms of ACR-induced peripheral neuropathy.
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Affiliation(s)
- Sufang Yu
- Institute of toxicology, Shandong University, 44 Wenhua Xi Road, Jinan, 250012, Shandong, P.R. China
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11
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Lee KY, Shibutani M, Kuroiwa K, Takagi H, Inoue K, Nishikawa H, Miki T, Hirose M. Chemoprevention of acrylamide toxicity by antioxidative agents in rats—effective suppression of testicular toxicity by phenylethyl isothiocyanate. Arch Toxicol 2005; 79:531-41. [PMID: 15864552 DOI: 10.1007/s00204-005-0656-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Accepted: 01/24/2005] [Indexed: 10/25/2022]
Abstract
The efficacies of N-acetylcysteine (NAC), phenylethyl isothiocyanate (PEITC), and 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ) at preventing the neurotoxicity and testicular toxicity of acrylamide (ACR) were investigated in rats. To this end, Sprague-Dawley males were given 0.02% ACR in drinking water, with or without 1% NAC, 0.5% PEITC or 0.1% HTHQ in the diet for four weeks. A group of untreated controls was also included in the study. All ACR-treated animals exhibited progressive neurotoxicity as judged by gait scores, and among the chemicals co-administered, only HTHQ caused any suppression by the end of the experiment, and this was slight. The severity of the neurotoxicity, as judged by axonal degeneration in the spinal gracile fasciculus and sciatic nerve (distal portion) and aberrant dot-like synaptophysin immunoreactivity, reflecting nerve terminal degeneration in the cerebellar molecular layer, was not clearly reduced by co-administration of HTHQ, NAC or PEITC either. ACR-induced sciatic nerve axon atrophy was marginally and non-significantly reduced by HTHQ. In contrast, in terms of ACR-induced testicular toxicity, exfoliation of spermatids into seminiferous lumen was clearly reduced by co-administered PEITC and was marginally reduced by co-administered HTHQ. These antioxidative agents may therefore reduce/prevent ACR-induced toxicity, at least in the testes.
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Affiliation(s)
- Kyoung-Youl Lee
- Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
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Beirowski B, Adalbert R, Wagner D, Grumme DS, Addicks K, Ribchester RR, Coleman MP. The progressive nature of Wallerian degeneration in wild-type and slow Wallerian degeneration (WldS) nerves. BMC Neurosci 2005; 6:6. [PMID: 15686598 PMCID: PMC549193 DOI: 10.1186/1471-2202-6-6] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Accepted: 02/01/2005] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The progressive nature of Wallerian degeneration has long been controversial. Conflicting reports that distal stumps of injured axons degenerate anterogradely, retrogradely, or simultaneously are based on statistical observations at discontinuous locations within the nerve, without observing any single axon at two distant points. As axon degeneration is asynchronous, there are clear advantages to longitudinal studies of individual degenerating axons. We recently validated the study of Wallerian degeneration using yellow fluorescent protein (YFP) in a small, representative population of axons, which greatly improves longitudinal imaging. Here, we apply this method to study the progressive nature of Wallerian degeneration in both wild-type and slow Wallerian degeneration (WldS) mutant mice. RESULTS In wild-type nerves, we directly observed partially fragmented axons (average 5.3%) among a majority of fully intact or degenerated axons 37-42 h after transection and 40-44 h after crush injury. Axons exist in this state only transiently, probably for less than one hour. Surprisingly, axons degenerated anterogradely after transection but retrogradely after a crush, but in both cases a sharp boundary separated intact and fragmented regions of individual axons, indicating that Wallerian degeneration progresses as a wave sequentially affecting adjacent regions of the axon. In contrast, most or all WldS axons were partially fragmented 15-25 days after nerve lesion, WldS axons degenerated anterogradely independent of lesion type, and signs of degeneration increased gradually along the nerve instead of abruptly. Furthermore, the first signs of degeneration were short constrictions, not complete breaks. CONCLUSIONS We conclude that Wallerian degeneration progresses rapidly along individual wild-type axons after a heterogeneous latent phase. The speed of progression and its ability to travel in either direction challenges earlier models in which clearance of trophic or regulatory factors by axonal transport triggers degeneration. WldS axons, once they finally degenerate, do so by a fundamentally different mechanism, indicated by differences in the rate, direction and abruptness of progression, and by different early morphological signs of degeneration. These observations suggest that WldS axons undergo a slow anterograde decay as axonal components are gradually depleted, and do not simply follow the degeneration pathway of wild-type axons at a slower rate.
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Affiliation(s)
- Bogdan Beirowski
- Center for Molecular Medicine Cologne (CMMC) and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50647 Cologne, Germany
- Department of Anatomy I, University of Cologne, Joseph-Stelzmann Strasse 9, D-50931 Cologne, Germany
| | - Robert Adalbert
- Center for Molecular Medicine Cologne (CMMC) and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50647 Cologne, Germany
- Babraham Institute, Babraham, Cambridge CB2 4 AT, UK
| | - Diana Wagner
- Center for Molecular Medicine Cologne (CMMC) and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50647 Cologne, Germany
| | - Daniela S Grumme
- Center for Molecular Medicine Cologne (CMMC) and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50647 Cologne, Germany
| | - Klaus Addicks
- Department of Anatomy I, University of Cologne, Joseph-Stelzmann Strasse 9, D-50931 Cologne, Germany
| | - Richard R Ribchester
- Division of Neuroscience, University of Edinburgh, 1 George Square, Edinburgh, EH8 9JZ, UK
| | - Michael P Coleman
- Center for Molecular Medicine Cologne (CMMC) and Institute for Genetics, University of Cologne, Zuelpicher Strasse 47, D-50647 Cologne, Germany
- Babraham Institute, Babraham, Cambridge CB2 4 AT, UK
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Pradat PF, Kennel P, Naimi-Sadaoui S, Finiels F, Orsini C, Revah F, Delaere P, Mallet J. Continuous delivery of neurotrophin 3 by gene therapy has a neuroprotective effect in experimental models of diabetic and acrylamide neuropathies. Hum Gene Ther 2001; 12:2237-49. [PMID: 11779407 DOI: 10.1089/10430340152710577] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Neurotrophic factors (NFs) are promising agents for the treatment of peripheral neuropathies such as diabetic neuropathy. However, the value of treatment with recombinant NF is limited by the short half-lives of these molecules, which reduces efficiency, and by their potential toxicity. We explored the use of intramuscular injection of a recombinant adenovirus encoding NT-3 (AdNT-3) to deliver sustained low doses of NT-3. We assessed its effect in two rat models: streptozotocin (STZ)-induced diabetes, a model of early diabetic neuropathy characterized by demyelination, and acrylamide experimental neuropathy, a model of diffuse axonal neuropathy which, like late-onset human diabetic neuropathy, results in a diffuse sensorimotor neuropathy with dysautonomy. Treatment of STZ-diabetic rats with AdNT-3 partially prevented the slowing of motor and sensory nerve conduction velocities (p < 0.01 and p < 0.0001, respectively). Treatment with AdNT-3 of acrylamide-intoxicated rats prevented the slowing of motor and nerve conduction velocities (p < 0.001 and p < 0.0001, respectively) and the decrease in amplitude of compound muscle potentials (p < 0.0001), an index of denervation. Acrylamide-intoxicated rats treated with NT-3 had higher than control levels of muscle choline acetyltransferase activity (p < 0.05), suggesting greater muscle innervation. In addition, treatment of acrylamide-intoxicated rats with AdNT-3 significantly improved behavioral test results. Treatment with AdNT-3 was well tolerated with minimal muscle inflammation and no detectable general side effects. Therefore, our results suggest that NT-3 delivery by adenovirus-based gene therapy is a promising strategy for the prevention of both early diabetic neuropathy and axonal neuropathies, especially late axonal diabetic neuropathy.
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Affiliation(s)
- P F Pradat
- Laboratoire de Génétique Moléculaire de la Neurotransmission et des Processus Neurodégénératifs (LGN), UMR C9923, Centre National de la Recherche Scientifique, Hôpital de la Pitié-Salpétrière, 75651 Paris Cedex 13, France
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LoPachin RM, Lehning EJ, Opanashuk LA, Jortner BS. Rate of neurotoxicant exposure determines morphologic manifestations of distal axonopathy. Toxicol Appl Pharmacol 2000; 167:75-86. [PMID: 10964758 DOI: 10.1006/taap.2000.8984] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exposure to a variety of agricultural, industrial, and pharmaceutical chemicals produces nerve damage classified as a central-peripheral distal axonopathy. Morphologically, this axonopathy is characterized by distal axon swellings and secondary degeneration. Over the past 25 years substantial research efforts have been devoted toward deciphering the molecular mechanisms of these presumed hallmark neuropathic features. However, recent studies suggest that axon swelling and degeneration are related to subchronic low-dose neurotoxicant exposure rates (i.e., mg toxicant/kg/day) and not to the development of neurophysiological deficits or behavioral toxicity. This suggests these phenomena are nonspecific and of uncertain pathophysiologic relevance. This possibility has significant implications for research investigating mechanisms of neurotoxicity, development of exposure biomarkers, design of risk assessment models, neurotoxicant classification schemes, and clinical diagnosis and treatment of toxic neuropathies. In this commentary we will review the evidence for the dose-related dependency of distal axonopathies and discuss how this concept might influence our current understanding of chemical-induced neurotoxicities.
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Affiliation(s)
- R M LoPachin
- Department of Anesthesiology, Albert Einstein College of Medicine/Montefiore Medical Center, 111 E. 210th Street, Bronx, New York, 10467-2490, USA.
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15
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Abstract
Nerve damage classified as a central-peripheral distal axonopathy is produced by a variety of chemicals (e.g. acrylamide, n-hexane). Historically, axon swelling and secondary degeneration have been considered the morphologic hallmarks of toxic axonopathies and substantial research has been devoted toward deciphering corresponding molecular mechanisms. However, recent studies from the author's laboratory investigating rate (mg toxicant/kg/day) and route (i.p. vs gavage) of intoxication have shown that swelling and degeneration were related to neurotoxicant dosing conditions (i.e. low-dose, subchronic exposure) and not to development of neurophysiological deficits or classic behavioral toxicity. This suggests the presumed hallmarks of distal axonopathy are epiphenomena of uncertain pathophysiologic significance. Therefore, the current definition of and chemical classification scheme for toxic distal axonopathies requires re-evaluation.
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Affiliation(s)
- R M LoPachin
- Anesthesia Research - Moses 7, Montefiore Medical Center, 111 E. 210th St., Bronx, New York, NY, USA.
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Lopachin RM. Electron Probe X-Ray Microanalysis: a Tool for Elucidating the Role of Ions in Neuronal Physiology and Pathophysiology. Neuroscientist 1999. [DOI: 10.1177/107385849900500612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Electron probe x-ray microanalysis (EPMA) is a quantitative electron microscope technique that measures both water content (percentage water) and total (free plus bound) concentrations of biological elements in selected morphological compartments. Unlike other methods for determination of ion/element concentrations, EPMA permits simultaneous quantitation of several elements (Na, P, S, Cl, K, Ca, and Mg) and allows optical differentiation of nervous tissue cell types (i.e, neurons, glia) with subsequent analysis of respective submembrane regions or organelles (e.g, axoplasm, mitochondria, nuclei). EPMA, therefore, represents a powerful tool for extending our current understanding of elements/ions in neurophysiological processes. In addition, it is presumed that neuropathic injury disrupts normal intraneuronal Na+, K+, and Ca2+ distribution and that the structural and functional consequences are mediated by ion translocation. However, little specific information is available regarding how translocated ions distribute among subcellular anatomical compartments after injury. EPMA quantification of ion/element changes associated with various nervous tissue injury models has helped to elucidate corresponding pathophysiological mechanisms. In this review, we will discuss EPMA and the realized, as well as potential, contributions of this technique to deciphering the role of ions in neuronal physiology and pathophysiology. Our recent studies of axon degeneration during acrylamide intoxication will be described to illustrate the utility of EPMA.
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Affiliation(s)
- Richard M. Lopachin
- Department of Anesthesiology Montefiore Medical Center Albert Einstein College of Medicine Bronx, New York
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17
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Ko MH, Chen WP, Lin-Shiau SY, Hsieh ST. Age-dependent acrylamide neurotoxicity in mice: morphology, physiology, and function. Exp Neurol 1999; 158:37-46. [PMID: 10448416 DOI: 10.1006/exnr.1999.7102] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Acrylamide intoxication produces peripheral neuropathy characterized by weakness and ataxia in both humans and experimental animals. Previous studies on animals of different ages and species indicate that the longest and largest nerves are affected earlier with the major pathology in the terminal parts of axons, i.e., distal axonopathy. However, several issues have remained elusive; for example, what are the earliest pathological changes? An equally intriguing question is whether younger animals are more susceptible to acrylamide than older animals. To address these issues, we compared the vulnerability to acrylamide of 3- and 8-week-old mice. These mice were intoxicated with acrylamide in drinking water (400 ppm). The sequence of intoxication could be categorized into three stages. In the initial stage, there was no visible weakness or ataxia. The only noticeable changes were poor performance on the rota-rod test and swelling of motor nerve terminals. Obvious weakness and ataxia of hindlimbs developed gradually (here designated as the early stage). The weakness and ataxia progressed at variable speeds in mice of different ages, and eventually the forelimbs (quadriparesis) were affected in the late stage. Each stage appeared earlier in 3-week-old mice than in 8-week-old mice (7.1 +/- 1.1 vs 15.6 +/- 4.0 days, P < 0.01 for the early stage; and 15.3 +/- 2.1 vs 31.7 +/- 6.0 days, P < 0.01 for the late stage). The progression of neurological deficits was also faster in the younger mice (7.2 +/- 1.8 vs 16.3 +/- 4.2 days, P < 0.01). Pathological changes in the distal parts of motor nerves innervating hindfoot muscles were evaluated by combined cholinesterase histochemistry and immunocytochemistry for neuronal markers to demonstrate motor nerve terminals and neuromuscular junctions simultaneously. In the initial stage, there was axonal swelling in motor nerve terminals. As acrylamide intoxication continued, axonal swelling extended into junctional folds and into the intramuscular nerves, which resulted in Wallerian-like degeneration. Our results indicate that younger mice show a much higher susceptibility to acrylamide intoxication, and pathological changes precede neurological symptoms.
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Affiliation(s)
- M H Ko
- Department of Anatomy, College of Medicine, National Taiwan University, Taipei, Taiwan
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18
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Aschner M, Allen JW, Kimelberg HK, LoPachin RM, Streit WJ. Glial cells in neurotoxicity development. Annu Rev Pharmacol Toxicol 1999; 39:151-73. [PMID: 10331080 DOI: 10.1146/annurev.pharmtox.39.1.151] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neuroglial cells of the central nervous system include the astrocytes, oligodendrocytes, and microglia. Their counterparts in the peripheral nervous system are the Schwann cells. The term neuroglia comes from an erroneous concept originally coined by Virchow (1850), in which he envisioned the neurons to be embedded in a layer of connective tissue. The term, or its shortened form--glia, has persisted as the preferred generic term for these cells. A reciprocal relationship exists between neurons and glia, and this association is vital for mutual differentiation, development, and functioning of these cell types. Therefore, perturbations in glial cell function, as well as glial metabolism of chemicals to active intermediates, can lead to neuronal dysfunction. The purpose of this review is to explore neuroglial sites of neurotoxicant actions, discuss potential mechanisms of glial-induced or glial-mediated central nervous system and peripheral nervous system damage, and review the role of glial cells in neurotoxicity development.
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Affiliation(s)
- M Aschner
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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19
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Fullerton SM, Strittmatter WJ, Matthew WD. Peripheral sensory nerve defects in apolipoprotein E knockout mice. Exp Neurol 1998; 153:156-63. [PMID: 9743578 DOI: 10.1006/exnr.1998.6872] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Apolipoprotein E (apoE), a plasma lipoprotein involved in lipid metabolism, is also proposed to have important functions within the central and peripheral nervous systems. To investigate the function of apoE in the peripheral nervous system, we examined the structure of sciatic nerves in apoE-deficient (apoE KO) mice. In the normal peripheral nervous system, apoE is produced by nonmyelinating Schwann cells, suggesting a role for apoE in the support of unmyelinated thermal and nociceptive sensory afferents. Using electron microscopy, we have found that apoE KO mice have abnormal and reduced numbers of unmyelinated axons within the sciatic nerve. ApoE KO unmyelinated axons are irregularly shaped and separated by very little Schwann cell cytoplasm. ApoE KO myelinated fibers and myelin are ultrastructurally normal. Consistent with these morphological findings, apoE KO mice display reduced sensitivity to noxious thermal stimuli. These data provide in vivo support for the hypothesis that apoE promotes neuronal health and survival.
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Affiliation(s)
- S M Fullerton
- Joseph and Kathleen Bryan Alzheimer's Disease Research Center, Duke University Medical Center, Durham, North Carolina 27710, USA
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20
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Lehning EJ, Persaud A, Dyer KR, Jortner BS, LoPachin RM. Biochemical and morphologic characterization of acrylamide peripheral neuropathy. Toxicol Appl Pharmacol 1998; 151:211-21. [PMID: 9707497 DOI: 10.1006/taap.1998.8464] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To determine whether reduced Na+/K+-ATPase activity might be involved in acrylamide (ACR)-induced peripheral axon swelling and degeneration, rubidium (Rb+) transport was measured as an index of enzyme function. x-ray microanalysis was used to quantify elemental Rb uptake and accumulation in internodal myelinated axons, mitochondria, Schwann cells, and myelin of rat tibial nerve cryosections. Results demonstrated impairment of Rb uptake in tibial axons from orally intoxicated (2.8 mM ACR for 34 days), moderately affected rats. In severely affected oral rats (49 days), complete inhibition of Rb transport and frank axon degeneration were evident. However, in moderate-to-severely affected rats exposed to ACR via ip injection (50 mg/kg/day for 11 days), neither structural nor enzymatic changes were present in tibial fibers. These findings in nerve cryosections suggested inhibition of axolemmal Na+ pump activity and degeneration were dependent upon route of ACR administration. This possibility was substantiated by a quantitative longitudinal morphometric study of conventionally fixed tibial nerve. Oral ACR treatment (2.8 mM ACR for 15-49 days) was associated with progressive axon degeneration, which was preceded by atrophy. Axonal swellings were rarely (<1%) observed. In contrast, ip ACR injection (50 mg/kg/day for 5-11 days) produced classic behavioral neurotoxicity but did not alter axon morphology in tibial nerve. Thus, fiber degeneration and decreased Na+ pump activity were consequences of subchronic oral ACR administration. This parallel expression suggests a mechanistic relationship. However, the corresponding general neurotoxicological significance is unclear since, behavioral toxicity induced by ip ACR develops without structural and enzymatic changes in tibial nerve.
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Affiliation(s)
- E J Lehning
- Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York 10467-2490, USA
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21
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Minzenberg M, Berkelaar M, Bray G, McKerracher L. Changes in retinal ganglion cell axons after optic nerve crush: neurofilament expression is not the sole determinant of calibre. Biochem Cell Biol 1995; 73:599-604. [PMID: 8714678 DOI: 10.1139/o95-065] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
After injury in the central nervous system of adult mammals, many of the axons that remain attached to their intact cell bodies degenerate and decrease in calibre. To understand this process better, we have investigated the relationship between axonal loss, cell loss, and the time course of changes in axonal calibre. Optic nerves (ONs) were crushed and the numbers and sizes of axons remaining close to the cell bodies (2 mm from the eye) and near the site of the lesion (6 mm from the eye) were determined for nerves examined between 1 week and 3 months after injury. Comparison with the retinal ganglion cell (RGC) counts from the same animals revealed that axonal loss was concomitant with cell body loss for at least the first 2 weeks after injury. However, there was no significant change in the calibre of the surviving neurons until 1 month after injury. Thereafter, the axonal calibre was decreased equally along the ON. No progressive somatofugal atrophy was observed. These decreases in axonal calibre occur much later than the immediate drop in neurofilament (NF) expression that also follows injury. The late effect of injury on axonal calibre suggests that NF expression is not the sole determinant of axon size of the RGC fibers in the ON. Other factors are likely additional contributing factors, such as the decreased rate of axonal transport that would help maintain the axonal neurofilament content.
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Affiliation(s)
- M Minzenberg
- Centre for Research in Neuroscience, Montréal General Hospital Research Institute and McGill University, QC, Canada
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22
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Roberson MD, Toews AD, Bouldin TW, Weaver J, Goines ND, Morell P. NGFR-mRNA expression in sciatic nerve: a sensitive indicator of early stages of axonopathy. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1995; 28:231-8. [PMID: 7723622 DOI: 10.1016/0169-328x(94)00211-v] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Expression of the low-affinity nerve growth factor receptor (NGFR) in the sciatic nerve (particularly Schwann cells) is high during development but is downregulated upon establishment of the mature axon-Schwann cell relationship. NGFR is re-expressed by Schwann cells if this relationship is altered by degeneration of axons (axotomy) or myelin (tellurium intoxication). To determine the sensitivity of NGFR expression to axonal injury, we have assayed NGFR-mRNA levels in proximal and distal regions of nerves exposed to the axonopathic agents acrylamide and isoniazid, as well as in proximal and distal stumps of axotomized nerves. NGFR-mRNA was elevated in all three models and correlated regionally with sites of axonal perturbation. In distal regions of acrylamide- and isoniazid-intoxicated nerves, NGFR-mRNA was elevated at least 2 days prior to visible signs of axonal degeneration as assayed by morphological techniques utilizing light microscopy. NGFR-mRNA was also elevated in proximal regions of axotomized and acrylamide-intoxicated nerves prior to signs of axonal degeneration. In these models, increased mRNA expression correlated with alterations in the size distribution of axonal cross sections. The common response in all of these situations indicates that NGFR expression, in addition to being a marker for axonal degeneration, is also a sensitive indicator of less profound perturbations in normal axon-Schwann cell interactions, including early stages of axonopathy. We suggest that assay for NGFR-mRNA may be utilized as a rapid and simple method (relative to more labor-intensive morphological methods) to screen for peripheral neurotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M D Roberson
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill 27599, USA
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23
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Electron Probe X-Ray Microanalysis as a Tool for Discerning Mechanisms of Nerve Injury. Neurotoxicology 1995. [DOI: 10.1016/b978-012168055-8/50031-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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24
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Jabre JF. Electrophysiological Investigations of Toxic Neuropathies. Neurotoxicology 1995. [DOI: 10.1016/b978-012168055-8/50057-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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25
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Overgaard Larsen J, Tandrup T, Braendgaard H. The volume of Purkinje cells decreases in the cerebellum of acrylamide-intoxicated rats, but no cells are lost. Acta Neuropathol 1994; 88:307-12. [PMID: 7839823 DOI: 10.1007/bf00310374] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The effects of acrylamide intoxication on the numbers of granule and Purkinje cells and the volume of Purkinje cell perikarya have been evaluated with stereological methods. The analysis was carried out in the cerebella of rats that had received a dose of 33.3 mg/kg acrylamide, twice a week, for 7.5 weeks. The total numbers of cerebellar granule and Purkinje cells were estimated using the optical fractionator and the mean volume of the Purkinje cell perikarya was estimated with the vertical rotator technique. The volumes of the molecular layer, the granular cell layer and the white matter were estimated using the Cavalieri principle. The mean weight of the cerebellum of the intoxicated rats was 7% lower than that of the control rats (2P = 0.001). The numbers of the Purkinje cells and granule cells were the same in both groups, but the mean volume of the perikarya of the Purkinje cells in the intoxicated rats was 10.5% less than that of the control group (2P = 0.004). The volume of the granular cell layer was reduced by 15% (2P = 0.006) but there were no differences in the volumes of the molecular layer and the white matter in the intoxicated and control animals.
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26
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Tandrup T, Braendgaard H. Number and volume of rat dorsal root ganglion cells in acrylamide intoxication. JOURNAL OF NEUROCYTOLOGY 1994; 23:242-8. [PMID: 8035207 DOI: 10.1007/bf01275528] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Acrylamide intoxication induces a filamentous neuropathy with breakdown of distal axons and chromatolytic reaction of dorsal root ganglion cells. To obtain quantitative information about the perikaryal alterations neurons of the fifth lumbar dorsal root ganglion of rats were examined with stereological techniques following intoxication with a total dose of 500 mg acrylamide. Number, mean volume and distribution of neuron volume were estimated for each of the two cell subpopulations using optical disectors, the four-way-nucleator and systematic sampling techniques. In intoxicated rats perikaryal volume of A-cells was significantly reduced by 28%, from 63,200 micron3 (CV = 0.16) to 45,500 micron3 (CV = 0.19), whereas the volume of B-cells was unchanged. Numbers of A- and B-cells were preserved. The finding of a selective atrophy of A-cell perikaryal volume is in accordance with previous observations of predominant alterations of large myelinated sensory fibres and most likely reflects an attack on the perikaryal neurofilaments abundant in this cell type.
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Affiliation(s)
- T Tandrup
- Stereological Research Laboratory, University of Aarhus, Denmark
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27
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LoPachin RM, Castiglia CM, Lehning E, Saubermann AJ. Effects of acrylamide on subcellular distribution of elements in rat sciatic nerve myelinated axons and Schwann cells. Brain Res 1993; 608:238-46. [PMID: 8495358 DOI: 10.1016/0006-8993(93)91464-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Electron probe X-ray microanalysis was used to determine whether experimental acrylamide (ACR) neuropathy involves deregulation of subcellular elements (Na, P, S, Cl, K, Ca and Mg) and water in Schwann cells and small, medium and large diameter myelinated axons of rat sciatic nerve. Results show that in proximal but not distal sciatic nerve, ACR treatment (2.8 mM in drinking water) was associated with an early (15 days of exposure), moderate increase in mean axoplasmic K concentrations (mmol/kg) of medium and small diameter fibers. However, all axons in proximal and distal nerve regions displayed small increases in dry and wet weight contents of axoplasmic Na and P. As ACR treatment progressed (up to 60 days of exposure), Na and P changes persisted whereas proximal axonal K levels returned to control values or below. Alterations in mitochondrial elemental content paralleled those occurring in axoplasm. Schwann cells in distal sciatic nerve exhibited a progressive loss of K, Mg and P and an increase in Na, Cl and Ca. Proximal glia displayed less extensive elemental modifications. Elemental changes observed in axons are not typical of those associated with cell injury and might reflect compensatory or secondary responses. In contrast, distal Schwann cell alterations are consistent with injury, but whether these changes represent primary or secondary mechanisms remains to be determined.
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Affiliation(s)
- R M LoPachin
- Department of Anesthesiology, Medical School, SUNY, Stony Brook 11794-8480
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