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Hwang Y, Park JH, Kim HC, Shin EJ. GABA B receptor activation alters astrocyte phenotype changes induced by trimethyltin via ERK signaling in the dentate gyrus of mice. Life Sci 2023; 319:121529. [PMID: 36841471 DOI: 10.1016/j.lfs.2023.121529] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/11/2023] [Accepted: 02/20/2023] [Indexed: 02/25/2023]
Abstract
AIMS We examined the effect of γ-aminobutyric acid (GABA)B receptor activation on astrocyte phenotype changes induced by trimethyltin (TMT) in the dentate gyrus of mice. MAIN METHODS Male C57BL/6N mice received TMT (2.6 mg/kg, i.p.), and the expression of GABAB receptors was evaluated in the hippocampus. The GABAB receptor agonist baclofen (2.5, 5, or 10 mg/kg, i.p. × 5 at 12-h intervals) was administered 3-5 days after TMT treatment, and the expression of Iba-1, GFAP, and astrocyte phenotype markers was evaluated 6 days after TMT. SL327 (30 mg/kg, i.p.), an extracellular signal-related kinase (ERK) inhibitor, was administered 1 h after each baclofen treatment. KEY FINDINGS TMT insult significantly induced the astroglial expression of GABAB receptors in the dentate molecular layer. Baclofen significantly promoted the expression of S100A10, EMP1, and CD109, but not that of C3, GGTA1, and MX1 induced by TMT. In addition, baclofen significantly increased the TMT-induced expression of p-ERK in the dentate molecular layer. Interestingly, p-ERK was more colocalized with S100A10 than with C3 after TMT insult, and a significant positive correlation was found between the expression of p-ERK and S100A10. Consistently, SL327 reversed the effect of baclofen on astrocyte phenotype changes. Baclofen also enhanced the TMT-induced astroglial expression of glial cell-derived neurotrophic factor (GDNF), an anti-inflammatory astrocytes-to-microglia mediator, and consequently attenuated Iba-1 expression and delayed apoptotic neuronal death. SIGNIFICANCE Our results suggest that GABAB receptor activation increases S100A10-positive anti-inflammatory astrocytes and astroglial GDNF expression via ERK signaling after TMT excitotoxicity in the dentate molecular layer of mice.
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Affiliation(s)
- Yeonggwang Hwang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Jung Hoon Park
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea.
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea.
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Hwang Y, Kim HC, Shin EJ. Effect of rottlerin on astrocyte phenotype polarization after trimethyltin insult in the dentate gyrus of mice. J Neuroinflammation 2022; 19:142. [PMID: 35690821 PMCID: PMC9188234 DOI: 10.1186/s12974-022-02507-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 06/01/2022] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND It has been demonstrated that reactive astrocytes can be polarized into pro-inflammatory A1 phenotype or anti-inflammatory A2 phenotype under neurotoxic and neurodegenerative conditions. Microglia have been suggested to play a critical role in astrocyte phenotype polarization by releasing pro- and anti-inflammatory mediators. In this study, we examined whether trimethyltin (TMT) insult can induce astrocyte polarization in the dentate gyrus of mice, and whether protein kinase Cδ (PKCδ) plays a role in TMT-induced astrocyte phenotype polarization. METHODS Male C57BL/6 N mice received TMT (2.6 mg/kg, i.p.), and temporal changes in the mRNA expression of A1 and A2 phenotype markers were evaluated in the hippocampus. In addition, temporal and spatial changes in the protein expression of C3, S100A10, Iba-1, and p-PKCδ were examined in the dentate gyrus. Rottlerin (5 mg/kg, i.p. × 5 at 12-h intervals) was administered 3-5 days after TMT treatment, and the expression of A1 and A2 transcripts, p-PKCδ, Iba-1, C3, S100A10, and C1q was evaluated 6 days after TMT treatment. RESULTS TMT treatment significantly increased the mRNA expression of A1 and A2 phenotype markers, and the increased expression of A1 markers remained longer than that of A2 markers. The immunoreactivity of the representative A1 phenotype marker, C3 and A2 phenotype marker, S100A10 peaked 6 days after TMT insult in the dentate gyrus. While C3 was expressed evenly throughout the dentate gyrus, S100A10 was highly expressed in the hilus and inner molecular layer. In addition, TMT insult induced microglial p-PKCδ expression. Treatment with rottlerin, a PKCδ inhibitor, decreased Iba-1 and C3 expression, but did not affect S100A10 expression, suggesting that PKCδ inhibition attenuates microglial activation and A1 astrocyte phenotype polarization. Consistently, rottlerin significantly reduced the expression of C1q and tumor necrosis factor-α (TNFα), which has been suggested to be released by activated microglia and induce A1 astrocyte polarization. CONCLUSION We demonstrated the temporal and spatial profiles of astrocyte polarization after TMT insult in the dentate gyrus of mice. Taken together, our results suggest that PKCδ plays a role in inducing A1 astrocyte polarization by promoting microglial activation and consequently increasing the expression of pro-inflammatory mediators after TMT insult.
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Affiliation(s)
- Yeonggwang Hwang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea.
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon, 24341, Republic of Korea.
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Hwang Y, Kim HC, Shin EJ. Enhanced neurogenesis is involved in neuroprotection provided by rottlerin against trimethyltin-induced delayed apoptotic neuronal damage. Life Sci 2020; 262:118494. [PMID: 32991881 DOI: 10.1016/j.lfs.2020.118494] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/12/2020] [Accepted: 09/20/2020] [Indexed: 12/26/2022]
Abstract
AIMS We here investigated the effect of late- and post-ictal treatment with rottlerin, a polyphenol compound isolated from Mallotus philippinensis, on delayed apoptotic neuronal death induced by trimethyltin (TMT) in mice. MAIN METHODS Male C57BL/6N mice received a single injection of TMT (2.4 mg/kg, i.p.), and mice were treated with rottlerin after a peak time (i.e., 2 d post-TMT) of convulsive behaviors and apoptotic cell death (5.0 mg/kg, i.p. at 3 and 4 d after TMT injection). Object location test and tail suspension test were performed at 5 d after TMT injection. In addition, changes in the expression of apoptotic and neurogenic markers in the dentate gyrus were examined. KEY FINDINGS Late- and post-ictal treatment with rottlerin suppressed delayed neuronal apoptosis in the dentate gyrus, and attenuated memory impairments (as evaluated by object location test) and depression-like behaviors (as evaluated by tail suspension test) at 5 days after TMT injection in mice. In addition, rottlerin enhanced the expression of Sox2 and DCX, and facilitated p-ERK expression in BrdU-incorporated cells in the dentate gyrus of TMT-treated mice. Rottlerin also increased p-Akt expression, and attenuated the increase in the ratio of pro-apoptotic factors/anti-apoptotic factors, and consequent cytosolic cytochrome c release and caspase-3 cleavage. Rottlerin-mediated action was significantly reversed by SL327, an ERK inhibitor. SIGNIFICANCE Our results suggest that late- and post-ictal treatment with rottlerin attenuates TMT-induced delayed neuronal apoptosis in the dentate gyrus of mice via promotion of neurogenesis and inhibition of an on-going apoptotic process through up-regulation of p-ERK.
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Affiliation(s)
- Yeonggwang Hwang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea.
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea.
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Evans HL. Behaviors in the Home Cage Reveal Toxicity: Recent Findings and Proposals for the Future. ACTA ACUST UNITED AC 2016. [DOI: 10.3109/10915818909009092] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Nervous system impairment is prominent among signs of chemical toxicity in humans and animals, yet evaluation of behavioral and neurologic responses is seldom included in premarket screening. The sensitivity and validity of automatically recorded rodent locomotor activity, whether inside or outside of the home cage, justifies its inclusion in first-tier testing. Home cage behaviors are studied in the toxicologic laboratory using quantitative techniques from behavioral neuroscience. A practical, noninvasive, automated system was developed and validated at New York University, in accord with Federal guidelines for testing neurotoxicity. Effects of neurotoxicants on motor activity, eating, drinking, and the daily cycle of rest-activity indicate sensitivity to a variety of chemicals as well as new avenues to the understanding of mechanisms of toxicity. The rat's pattern of nocturnal activity is particularly sensitive to neurotoxicants and thus deserves additional attention. The coefficient of variability of various end points did not correlate with sensitivity to toxicants. This underscores the need for behavioral data to supplement theoretical considerations in test selection. The system's advantages are economy, high data capacity, humaneness, accessible and well-known end points, widely available equipment, automation, and the potential for direct comparisons of several different animal species.
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Affiliation(s)
- Hugh L. Evans
- Institute of Environmental Medicine New York University Medical Center 550 First Avenue New York, NY 10016
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Crofton KM, Foss JA, Hass U, Jensen KF, Levin ED, Parker SP. Undertaking positive control studies as part of developmental neurotoxicity testing: a report from the ILSI Research Foundation/Risk Science Institute expert working group on neurodevelopmental endpoints. Neurotoxicol Teratol 2007; 30:266-87. [PMID: 17681747 DOI: 10.1016/j.ntt.2007.06.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2007] [Revised: 04/26/2007] [Accepted: 06/07/2007] [Indexed: 10/23/2022]
Abstract
Developmental neurotoxicity testing involves functional and neurohistological assessments in offspring during and following maternal and/or neonatal exposure. Data from positive control studies are an integral component in developmental neurotoxicity risk assessments. Positive control data are crucial for evaluating a laboratory's capability to detect chemical-induced changes in measured endpoints. Positive control data are also valuable in a weight-of-evidence approach to help determine the biological significance of results and provide confidence in negative results from developmental neurotoxicity (DNT) studies. This review is a practical guide for the selection and use of positive control agents in developmental neurotoxicology. The advantages and disadvantages of various positive control agents are discussed for the endpoints in developmental neurotoxicity studies. Design issues specific to positive control studies in developmental neurotoxicity are considered and recommendations on how to interpret and report positive control data are made. Positive control studies should be conducted as an integral component of the incorporation and use of developmental neurotoxicity testing methods in laboratories that generate data used in risk decisions.
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Affiliation(s)
- Kevin M Crofton
- Neurotoxicology Division, NHEERL, ORD, US EPA, Research Triangle Park, NC, USA.
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Halladay AK, Wilson DT, Wagner GC, Reuhl KR. Trimethyltin-induced alterations in behavior are linked to changes in PSA-NCAM expression. Neurotoxicology 2006; 27:137-46. [PMID: 16426681 DOI: 10.1016/j.neuro.2005.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Accepted: 06/08/2005] [Indexed: 10/25/2022]
Abstract
The neurotoxic heavy metal trimethyltin (TMT) primarily damages neurons of the hippocampus and limbic areas of the temporal lobe, and causes a dose-dependent decrease in the polysialated form of the neural cell adhesion molecule (PSA-NCAM) in the mouse hippocampus. In the current study, we attempted to associate deficits in spatial learning following TMT exposure at various stages in learning with changes in levels of NCAM-180 and PSA-NCAM in both the hippocampus and frontal cortex. Mice were treated with TMT either before or after training on a spatial learning paradigm and examined for changes in NCAM and PSA-NCAM 12h later. In the first set of experiments, male BALB/c mice were injected with TMT (2.25 mg/kg) or saline i.p. and tested 24-168 h later using hidden and visible versions of the water maze, as well as light avoidance and motor activity. Mice in both treated and control groups which demonstrated a significant improvement in water maze performance also showed an elevation in hippocampal PSA-NCAM at all time points examined. TMT exposure impaired spatial learning and blocked learning-induced elevations in PSA-NCAM expression 24-96 h post-treatment, but these deficits disappeared by 168 h post-treatment. Mice exposed to TMT during reconsolidation of spatial learning (after repeated water maze training) demonstrated a mild and transient difference in escape latency compared to saline exposed mice. TMT administration during this period did not result in the attenuation of PSA-NCAM expression observed when animals were exposed before training. These results confirm a specific role for PSA-NCAM in acquisition and consolidation of spatial memory.
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Affiliation(s)
- A K Halladay
- Joint Graduate Program in Toxicology, Rutgers University, Piscataway, NJ, USA
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MacPhail RC, O'Callaghan JP, Cohn J. Acquisition, steady-state performance, and the effects of trimethyltin on the operant behavior and hippocampal GFAP of Long-Evans and Fischer 344 rats. Neurotoxicol Teratol 2003; 25:481-90. [PMID: 12798965 DOI: 10.1016/s0892-0362(03)00012-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Strain differences represent an overlooked variable that may play an important role in neurotoxic outcomes that can impact regulatory decision making. Here, we examined the strain-dependent effects of trimethyltin (TMT), a compound used as a positive control for behavioral and neurochemical assessments of neurotoxicity. Adult male Long-Evans (LE) and Fischer 344 (F344) rats (n=12 each) were trained to respond under a multiple, fixed-interval 3-min fixed-ratio 10-response (multi FI 3-min FR10) schedule of milk reinforcement. Acquisition was characterized by time-dependent changes in several behavioral endpoints in both strains, although rate of acquisition of the fixed-interval pattern of responding was slower in F344 rats. Steady-state (baseline) performance was characterized by slower overall rates of responding in F344 rats. There was little evidence of strain differences in many of the other baseline performance measures. Rats of each strain were then divided into two equal groups that received either 1 ml/kg saline or 8.0 mg/kg iv TMT approximately 18 h before the next test session. TMT produced transient changes in the performance of LE and F344 rats that lasted for several sessions. For many behavioral measures, F344 rats were more affected by TMT than were LE rats. TMT-induced reactive gliosis, as assessed by assaying glial fibrillary acidic protein (GFAP), was also greater in F344 rats than in LE rats. These results suggest F344 rats may be more susceptible to TMT-induced neurotoxicity than are LE rats.
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Affiliation(s)
- R C MacPhail
- Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
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8
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Abstract
Injury to the brain usually manifests not in a diffuse uniform manner but rather with selective sites of damage indicative of differential vulnerability. This question of neuronal susceptibility has been one of major interest both in disease processes as well as damage induced by environmental factors. For experimental examination, brain structures with obvious neuronal subpopulations and organization such as the cerebellum and the hippocampus have offered the most promise. In the hippocampus distinct neuronal populations exist that demonstrate differential vulnerability to various forms of insult including ischemia, excitotoxicity, and environmental factors. The more recent data regarding the presence of neuronal progenitor cells in the subgranular zone of the dentate offers the opportunity to expand such experimental examination to the process of injury-induced neurogenesis. Thus, more recent studies have expanded the examination of the hippocampus to include models of damage to the dentate neurons in addition to the highly vulnerable pyramidal neurons. A number of these models are presented for both human disease and experimental animal conditions. Examination of the responses between these distinct cell populations offers the potential for understanding factors that are critical in neuronal death and survival.
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Affiliation(s)
- G Jean Harry
- Neurotoxicology Group, Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, 27709, Research Triangle Park, NC, USA.
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Ekuta JE, Allgood JC, O'Neal JM, Matthews JC. Detection and Analysis of Methyltins in Extracts from Mouse Tissues Following Injection of Trimethyltin. ANAL LETT 1998. [DOI: 10.1080/00032719808005291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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10
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Abstract
Sixteen week old male AKR/J, Balb/cByJ, C57B1/6J and DBA/2J mice received single i.p. injections of trimethyltin (TMT). The toxic effects were weight loss, hyperexcitability, tremor, clonic-tonic convulsion, posterior paresis and death. The minimum toxic dose was 1.8 mg/kg, for the AKR strain and 2.3 mg/kg for the other strains. The highest non-lethal dose was 2.7 mg/kg for the AKR, DBA/2 and C57B1/6 strains and 3.0 mg/kg for the Balb/c strain. Blood levels of TMT peaked within 1 h and declined with half-lives of approximately 1.5 days. Blood levels of TMT were lower in the C57B1/6 mice due to greater tissue binding of TMT in C57B1/6 mice. Some of the toxic endpoints showed different rank orders among the strains, leading us to conclude that more than one biological process is responsible for the acute toxic effects of TMT in mice.
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Affiliation(s)
- J E Ekuta
- Department of Pharmacology, School of Pharmacy, The University of Mississippi, University 38677, USA
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Abstract
Behavioral toxicology is a discipline which has evolved out of the need for data on the effects of toxic agents on the function of the central nervous system. To date the field is divided over the question of which behavioral models to use to detect behavioral toxicities. Operant conditioning and schedule-controlled responding have been used as baselines for testing pharmacological agents for nearly 40 years, and there is no reason that the developing field of behavioral toxicology cannot take advantage of the lessons learned during this 40-year period. Behaviors maintained by operant conditioning procedures have proven to be sensitive to a wide range of chemicals. Using these procedures, behavior has been shown to; be sensitive to toxic agents, provide data relevant to the question of behavioral specificity, provide a stable baseline for extended periods of time, and allow for the assessment of specific functions such as temporal discrimination, learning and memory, and sensory system function.
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Affiliation(s)
- G R Wenger
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock 72205
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12
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Bushnell PJ. Delay-dependent impairment of reversal learning in rats treated with trimethyltin. BEHAVIORAL AND NEURAL BIOLOGY 1990; 54:75-89. [PMID: 2378608 DOI: 10.1016/0163-1047(90)91261-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recent theories of hippocampal function focus on its role in the formation of associations in the temporal domain. A reversal learning paradigm based on leverpress automaintenance was developed to vary the CS-US relationship along two independent dimensions, one temporal and one not: CS(+)-US delay and the probability of reinforcement [P(RFT)] following the CS+. Eight male hooded Long-Evans rats were trained to reverse these automaintained discriminations repeatedly, until stable performance was achieved. The neurotoxicant trimethyltin (TMT) was used to induce lesions in the CNS, including the CA3-4 region of Ammon's Horn in dorsal hippocampus. Following iv injection of 7 mg/kg TMT to half the rats, reversal learning was assessed under varying conditions of delay and P(RFT). After recovery from the acute effects of TMT (1-2 weeks), treated rats reversed normally when no delay separated the CS+ and US; with delays of 2 to 4 s, they reversed less completely within a session than did controls. Changing P(RFT) did not affect reversal learning in either group, but reduced response rates similarly in both groups. Morphological damage was quantified by measuring the length of the remaining pyramidal cell line in sections of dorsal hippocampus. The degree of behavioral impairment correlated significantly with hippocampal damage only at nonzero CS(+)-US delays. These results indicate that TMT impaired ability of rats to integrate temporal relationships between stimulus events, and are consistent with theories of hippocampal mediation of temporal associations.
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Affiliation(s)
- P J Bushnell
- Neurotoxicology Division, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711
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Christ D, Chang LW, McMillan DE. Neurotoxicological effects of trimethyltin on the stellate ganglion. Neurotoxicol Teratol 1989; 11:453-60. [PMID: 2593985 DOI: 10.1016/0892-0362(89)90023-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hamsters treated with trimethyltin (TMT), 3 or 4 mg/kg IP, developed neurological symptoms, including tremor, within 24 hours. Postganglionic action potentials were recorded from isolated stellate ganglia of untreated hamsters (control ganglia) and TMT-treated hamsters (TMT ganglia). Compound action potentials (nicotinic transmission) of control and TMT ganglia were not significantly different. The afterdischarges induced by preganglionic stimulation at 30 Hz for 2 sec in the presence of 10(-3) M hexamethonium (muscarinic transmission) were significantly smaller in TMT ganglia than in control ganglia. The discharges induced by the muscarinic cholinoceptor agonist. McN-A-343, were also smaller in the TMT ganglia. Two other muscarinic processes, posttetanic potentiation and potentiation of the compound action potential by McN-A-343, were not significantly reduced in the TMT ganglia. Morphological studies of the ganglia revealed marked changes in the TMT ganglia with severe neuronal degeneration including vacuole formations and accumulations of lysosomes in the cytoplasm. These results demonstrate that TMT has marked anatomical effects on the stellate ganglion that may lead to the reduction in muscarinic cholinergic transmission.
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Affiliation(s)
- D Christ
- Department of Pharmacology & Interdisciplinary Toxicology, University of Arkansas for Medical Sciences, Little Rock 72205
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Golub MS, Donald JM, Gershwin ME, Keen CL. Effects of aluminum ingestion on spontaneous motor activity of mice. Neurotoxicol Teratol 1989; 11:231-5. [PMID: 2755419 DOI: 10.1016/0892-0362(89)90064-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Aluminum (Al) as aluminum lactate in a purified diet was fed to adult female Swiss-Webster mice over a six week period. Comparison groups were: controls (CON), 25 micrograms Al/g diet; low Al (LO), 500 micrograms Al/g diet; high Al (HI), 1000 micrograms Al/g diet; and pair fed (PF) 25 micrograms Al/g diet pair fed to HI group. Weights, food intake and toxic signs were recorded at 3-day intervals and activity levels were measured during a 24-hr session during week 5 using an automated apparatus. Food intake was not reduced overall in Al-treated groups but they demonstrated a cyclic pattern of food intake. Mean weight gain over the 6-week period in the HI (0.5 g) and PF(0.1 g) groups was somewhat less than that in the CON (2.3 g) and LO (2.0 g) groups. No neurotoxic signs were recorded in any group, but a dose dependent increase in localized fur loss was seen. Overall activity level was 20% lower in HI than CON groups, with vertical movement more affected than horizontal movement. HI mice were less active during the diurnal period of peak activity than CON mice and their activity periods were also somewhat shorter (130 vs. 200 min). Activity of LO and PF mice did not differ significantly from controls, although PF activity levels were more variable. These data demonstrate that short term feeding of aluminum at levels within an order of magnitude of estimated human intake can influence neurobehavioral function as indexed by motor activity.
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Affiliation(s)
- M S Golub
- Department of Internal Medicine, School of Medicine, University of California, Davis 95616
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Abstract
Naturalistic behaviors are behaviors that organisms exhibit 'in nature'. Eating, sleeping and sexual behaviors are examples. Since naturalistic behaviors are observed to occur without any apparent training or learning, some people mistakenly believe that all naturalistic behaviors are unlearned, and are thus different from laboratory behaviors. We maintain that naturalistic behaviors can be studied profitably in the toxicological laboratory, using quantitative techniques from behavioral neuroscience. Understanding of toxicity and underlying mechanisms is enhanced when naturalistic behaviors are thought of as responses to stimuli. Stimuli that influence naturalistic behaviors may arise inside the organisms (e.g., physiological signals of hunger) or outside the organisms (e.g., the smell of food or the start of the nocturnal lighting cycle). A practical, noninvasive, automated system can be used to improve upon the cage-side observation currently used to evaluate naturalistic behaviors in toxicity screening. Effects of alkyltins and other neurotoxicants upon eating, drinking, rearing, and the daily cycle of rest-activity will be shown. The rodent's pattern of nocturnal activity has proven to be particularly sensitive to neurotoxicants, and thus deserves additional attention in developing neurobehavioral toxicology.
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Affiliation(s)
- H L Evans
- Institute of Environmental Medicine, New York University Medical Center, NY 10016
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Chang LW. Possible pathogenic mechanisms on trimethyltin-induced lesions in the hippocampus of adult and neonatal rats : An overview. Biol Trace Elem Res 1987; 13:77-88. [PMID: 24254667 DOI: 10.1007/bf02796623] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The extent of trimethyltin (TMT) induced lesions in the rat hippocampal formation was reviewed. Adult rats were treated with a single dose of 6.0 mg TMT/kg body wt and were sacrificed between 3-60 d following exposure. In the hippocampal formation, the granule cells of fascia dentata showed early changes, which subsided considerably at a later time of the intoxication. On the other hand, destruction of the pyramidal neurons in the Ammon's horn became more pronounced with time, resulting in an extensive destruction of this structure. It is interesting to note that the CA3 neurons in the septal portion of the Ammon's horn were more vulnerable than those located more temporally, whereas the reverse pattern was observed for the dentate granule cells as well as for the CA1,2 neurons of the Ammon's horn. Special stain for zinc (Timm's method) also revealed a progressive depletion of zinc in the mossy fibers. When neonatal rats were treated at various times with a single injection of TMT, rapid and progressive destruction of the Ammon's horn was observed in animals injected between postnatal day (PND) 5-15. The progression of neuronal involvement was CA3b →CA3a, b →CA3(a,b,c)→CA3+CA2→entire Ammon's horn (CA1,2,3). This pattern of pathological lesion was in good concert with morphological development and functional maturity of the hippocampal formation. Destruction of the Ammon's horn neurons was proposed to be the result of hyperexcitation of the dentate granule neurons under the influence of TMT. Other possible mechanisms are also discussed.
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Affiliation(s)
- L W Chang
- Department of Pathology, University of Arkansas for Medical Sciences, 72205-7199, Little Rock, AR
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Ali SF, Newport GD, Slikker W, Bondy SC. Effect of trimethyltin on ornithine decarboxylase in various regions of the mouse brain. Toxicol Lett 1987; 36:67-72. [PMID: 3564070 DOI: 10.1016/0378-4274(87)90042-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Male C57B1/6N mice, 8-10 weeks old were given a single oral dose of 0, 1.0 or 3.0 mg/kg body weight of trimethyltin hydroxide (TMT). Levels of ornithine decarboxylase (ODC) activity were measured in several brain areas, 1, 2 and 7 days later. The lower dose of TMT produced a decrease of ODC in the caudate nucleus and hippocampus at all time points studied. Hypothalamus, cerebellum and brain stem levels of this enzyme were unaltered. At the higher dose of TMT, ODC activity in hippocampus, cerebellum and brain stem were increased relative to controls at 1 and 2 days after treatment, while other regions were not significantly affected. These elevated ODC levels returned to control values within 7 days. Thus, trimethyltin treatment causes changes in ODC activity in a region and dose-specific manner.
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Abstract
Diurnal patterns of feeding, drinking, locomotor activity, and rearing in male Fischer-344 rats were examined for 2 weeks after a single oral dose of trimethyltin chloride (TMT) at 0, 3, 5, or 7 mg/kg. Body weights and feeding and drinking efficiency ratios (ratios of amount of food or water consumed per unit effort) were also determined daily. TMT caused a dose- and time-related drop in body weight; two of five rats in the 7 mg/kg group were killed moribund on 15 days after dosing. Feed consumption fell to 25% of control within 5 days after 7 mg/kg TMT, and to 50% of control for Days 2 and 3 after 5 mg/kg TMT. Water consumption doubled within 2 days after 7 mg/kg TMT and remained elevated for 2 weeks. Feeding efficiency dropped to 40% of control after 7 mg/kg, but drinking efficiency was unchanged. The diurnal patterns of drinking and of rearing were disrupted at all doses of TMT; a normal peak in rearing activity, occurring immediately prior to light onset, was markedly attenuated after all doses on Day 3, and at 5 and 7 mg/kg on Days 5 and 7 post-TMT. These results suggest (1) that the regulation of feed and water intake is severely compromised after a high dose of TMT, and (2) that the rat's cyclical patterns of homecage behavior are sensitive to TMT doses as low as 3 mg/kg.
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21
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Webber RJ, Dollins SC, Harris M, Hough AJ. Effect of alkyltins on rabbit articular and growth-plate chondrocytes in monolayer culture. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH 1985; 16:229-42. [PMID: 4078933 DOI: 10.1080/15287398509530736] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The effect of four different alkyltins (trimethyltin, triethyltin, dibutyltin, and dioctyltin) on the metabolism of rabbit articular and growth-plate chondrocytes was investigated using a monolayer cell-culture system. In most instances the compounds tested exhibited a general cytotoxic effect on these cells, inhibiting the synthesis of both DNA and sulfated proteoglycans. The effect of these compounds on proteoglycan synthesis was both quantitative and qualitative, as demonstrated by CsCl isopycnic density gradient centrifugation and gel exclusion chromatographic techniques. However, certain tin compounds tested, at specific concentrations, exerted a stimulatory effect on chondrocyte proliferation. Regarding DNA synthesis, growth-plate chondrocytes were more sensitive to the effect of the triethyltin, dibutyltin, and dioctyltin than were articular chondrocytes. The data are discussed in relation to the possible effects of the alkyltins on skeletal growth and development as well as the mechanism of action of the alkyltins at the molecular level.
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22
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Wenger GR, McMillan DE, Chang LW. Behavioral effects of trimethyltin in two strains of mice. II. Multiple fixed ratio, fixed interval. Toxicol Appl Pharmacol 1984; 73:89-96. [PMID: 6710519 DOI: 10.1016/0041-008x(84)90056-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Adult male C57BL/6N and BALB/c mice were trained to respond under a multiple fixed-ratio 30, fixed-interval 600-sec schedule of milk presentation. After performance had stabilized, each mouse received a single dose of trimethyltin X Cl (TMT) by ip administration. Three hours after administration, behavioral testing was started and continued at 24-hr intervals thereafter. The behavior of mice receiving 0.3 mg/kg was unaffected at 3, 27, and 51 hr after administration. Likewise, no effects were seen at 3 and 27 hr after 1 mg/kg. However, at 51 hr after administration there was a significant change in the temporal patterning of fixed-interval responding in the C57BL/6N strain, as shown by a decrease in the fixed-interval quarter-life. There was no significant change in the BALB/c strain at this dose. At 3 mg/kg the responding of both strains was greatly affected, and responding remained disrupted for at least 6 to 7 weeks. Neuropathological examination of the brains of both strains of mice showed no significant lesions (light microscopy) at 0.3 and 1 mg/kg. At 3 mg/kg, severe neuronal necrosis was observed in the fascia dentata region in both strains. Thus, in mice receiving TMT, the behavioral deficits were closely paralleled by the presence or absence of significant neuropathology.
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