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García-Jácome D, Martínez-Mota L, Páez-Martínez N. Effects of housing condition on the development and persistence of addictive-like behavior induced by toluene. Neurotoxicology 2024; 103:9-15. [PMID: 38801998 DOI: 10.1016/j.neuro.2024.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/16/2024] [Accepted: 05/17/2024] [Indexed: 05/29/2024]
Abstract
Environmental factors can modify addictive responses induced by drugs of abuse; however, little is known about the impact of environmental conditions on behavioral responses induced by inhalants. In this study, we analyzed the effects of housing conditions, considering environmental enrichment (EE; n = 10), social isolation (SI; n = 10), and standard housing (STD; n = 10), as positive, negative, and control environments, respectively, on the development and persistence of behavioral sensitization induced by toluene. Mice exposed to air were used as a comparative control groups for each housing condition (EE: n = 11, SI: n = 10 and STD: n = 11). Results showed that a history of toluene exposure induced the development of locomotor sensitization in mice, independent of their housing conditions. However, SI increased the expression of behavioral sensitization to toluene after a drug-free period.
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Affiliation(s)
- David García-Jácome
- Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Salvador Díaz Mirón, Casco de Santo Tomas, Miguel Hidalgo, 11340, Ciudad de México, México
| | - Lucía Martínez-Mota
- Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz. Calzada México-Xochimilco 101, Colonia San Lorenzo Huipulco, Tlalpan, 14370, Ciudad de México, México
| | - Nayeli Páez-Martínez
- Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Salvador Díaz Mirón, Casco de Santo Tomas, Miguel Hidalgo, 11340, Ciudad de México, México; Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz. Calzada México-Xochimilco 101, Colonia San Lorenzo Huipulco, Tlalpan, 14370, Ciudad de México, México.
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Davidson CJ, Hannigan JH, Perrine SA, Bowen SE. Abuse-like toluene exposure during early adolescence alters subsequent ethanol and cocaine behavioral effects and brain monoamines in male mice. Neurotoxicol Teratol 2024; 101:107317. [PMID: 38199311 DOI: 10.1016/j.ntt.2023.107317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 12/01/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024]
Abstract
Currently, there is a gap in understanding the neurobiological impact early adolescent toluene exposure has on subsequent actions of other drugs. Adolescent (PND 28-32) male Swiss-Webster mice (N = 210) were exposed to 0, 2000, or 4000 ppm of toluene vapor for 30 min/day for 5 days. Immediately following the last toluene exposure (PND 32; n = 15) or after a short delay (PND 35; n = 15), a subset of subjects' brains was collected for monoamine analysis. Remaining mice were assigned to one of two abstinence periods: a short 4-day (PND 36) or long 12-day (PND 44) delay after toluene exposure. Mice were then subjected to a cumulative dose response assessment of either cocaine (0, 2.5, 5, 10, 20 mg/kg; n = 60), ethanol (0, 0.5, 1, 2, 4 g/kg; n = 60), or saline (5 control injections; n = 60). Toluene concentration-dependently increased locomotor activity during exposure. When later challenged, mice exposed previously to toluene were significantly less active after cocaine (10 and 20 mg/kg) compared to air-exposed controls. Animals were also less active at the highest dose of alcohol (4 g/kg) following prior exposure to 4000 ppm when compared to air-exposed controls. Analysis of monoamines and their metabolites using High Pressure Liquid Chromatography (HPLC) within the medial prefrontal cortex (mPFC), nucleus accumbens (NAc), dorsal striatum (dSTR), and ventral tegmental area (VTA) revealed subtle effects on monoamine or metabolite levels following cumulative dosing that varied by drug (cocaine and ethanol) and abstinence duration. Our results suggest that early adolescent toluene exposure produces behavioral desensitization to subsequent cocaine-induced locomotor activity with subtle enhancement of ethanol's depressive effects and less clear impacts on levels of monoamines.
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Affiliation(s)
- Cameron J Davidson
- Department of Psychology, Wayne State University, Detroit, MI, USA; School of Medicine, Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, MI, USA.
| | - John H Hannigan
- Department of Psychology, Wayne State University, Detroit, MI, USA; School of Medicine, Department of Obstetrics & Gynecology, Wayne State University, Detroit, MI, USA; Merrill Palmer Skillman Institute for Child & Family Development, Wayne State University, Detroit, MI, USA; Center for Urban Responses to Environmental Stressors, Wayne State University, Detroit, MI, USA
| | - Shane A Perrine
- School of Medicine, Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, MI, USA
| | - Scott E Bowen
- Department of Psychology, Wayne State University, Detroit, MI, USA; Center for Urban Responses to Environmental Stressors, Wayne State University, Detroit, MI, USA; School of Medicine, Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, MI, USA.
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3
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Guo D, Zhan C, Liu J, Wang Z, Cui M, Zhang X, Su X, Pan L, Deng M, Zhao L, Liu J, Song Y. Alternations in neural oscillation related to attention network reveal influence of indoor toluene on cognition at low concentration. INDOOR AIR 2022; 32:e13067. [PMID: 35904384 DOI: 10.1111/ina.13067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/17/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Despite accumulative literature reporting negative impacts of high-concentration toluene, cognitive effects of toluene at low concentration are still unclear. Twenty-two healthy college students were exposed in a closed environmental chamber to investigate the influence of indoor toluene on cognitive performance and brain activity. During each toluene exposure condition (0 ppb, 17.5 ppb, 35 ppb, and 70 ppb), attention network test and electroencephalogram (EEG) recording were synchronously performed after 4-hour toluene exposure. Characteristic neural oscillation patterns in three attention networks were compared between four groups. The statistical analyses indicated that short-term exposure to toluene had no significant impact on behavioral performance of attention network. However, there was a significant increase in the power of theta and alpha band of executive network and orienting network in the whole brain, especially in frontal region when exposed to toluene. Besides, no significant difference was observed in alerting network. The alternations in neural oscillation demonstrated that more effort was required to accomplish the same tasks when exposed to toluene. The present study revealed that short-term exposure to toluene affected brain activity of attention network even at low concentration, which provided a theoretical basis for the development of safer evaluation methods and standards in the future.
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Affiliation(s)
- Dandan Guo
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin, China
- Key Laboratory of Post-Neuroinjury Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Neurological Institute, Tianjin, China
| | - Changqing Zhan
- Department of Neurology, Wuhu No.2 People's Hospital, Wuhu, China
| | - Jie Liu
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin, China
- Key Laboratory of Post-Neuroinjury Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Neurological Institute, Tianjin, China
| | - Zukun Wang
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Mingrui Cui
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin, China
- Key Laboratory of Post-Neuroinjury Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Neurological Institute, Tianjin, China
| | - Xin Zhang
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin, China
- Key Laboratory of Post-Neuroinjury Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Neurological Institute, Tianjin, China
| | - Xiao Su
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin, China
- Key Laboratory of Post-Neuroinjury Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Neurological Institute, Tianjin, China
| | - Liping Pan
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin, China
- Key Laboratory of Post-Neuroinjury Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Neurological Institute, Tianjin, China
| | - Meili Deng
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin, China
- Key Laboratory of Post-Neuroinjury Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Neurological Institute, Tianjin, China
| | - Lei Zhao
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Junjie Liu
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Yijun Song
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin, China
- Key Laboratory of Post-Neuroinjury Neuro-repair and Regeneration in Central Nervous System, Ministry of Education, Tianjin Neurological Institute, Tianjin, China
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Campos-Ordoñez T, Alcalá E, Ibarra-Castañeda N, Buriticá J, González-Pérez Ó. Chronic exposure to cyclohexane induces stereotypic circling, hyperlocomotion, and anxiety-like behavior associated with atypical c-Fos expression in motor- and anxiety-related brain regions. Behav Brain Res 2021; 418:113664. [PMID: 34780858 DOI: 10.1016/j.bbr.2021.113664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 10/29/2021] [Accepted: 11/07/2021] [Indexed: 12/27/2022]
Abstract
Recreational abuse of solvents continues, despite cyclohexane (CHX) is used as a safe replacement in gasoline or adhesive formulations. Increasing evidence indicates that CHX inhalation affects brain functioning; however, scanty information is available about its effects on behavior and brain activity upon drug removal. In this study, we used CD1 adult mice to mimic an intoxication period of recreational drugs for 30 days. During the CHX exposure (~30,000 ppm), we analyzed exploratory and biphasic behaviors, stereotypic circling, and locomotion. After CHX removal (24 h or a month later), we assessed anxiety-like behaviors and quantified c-Fos cells in motor- and anxiety-related brain regions. Our findings indicate that the repeated inhalation of CHX produced steady hyperactivity and reduced ataxia, sedation, and seizures as the exposure to CHX progressed. Also, CHX decreased grooming and rearing behaviors. In the first week of CHX inhalation, a stereotypic circling behavior emerged, and locomotion increased gradually. One month after CHX withdrawal, mice showed low activity in the center zone of the open field and more buried marbles. Twenty-four hours after CHX removal, c-Fos expression was low in the dorsal striatum, ventral striatum, motor cortex, dorsomedial prefrontal cortex, basolateral amygdala, lateral hypothalamus, and ventral hippocampus. One month later, c-Fos expression remained low in the ventral striatum and lateral hypothalamus but increased in the dorsomedial prefrontal cortex and primary motor cortex. This study provides a comprehensive behavioral characterization and novel histological evidence of the CHX effects on the brain when is administered in a recreational-like mode.
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Affiliation(s)
- Tania Campos-Ordoñez
- Laboratory of Neuroscience, School of Psychology, University of Colima, Colima, Mexico; Centro de Estudios e Investigaciones en Comportamiento, University of Guadalajara, Jalisco, Mexico.
| | - Emmanuel Alcalá
- Centro de Estudios e Investigaciones en Comportamiento, University of Guadalajara, Jalisco, Mexico; Research Laboratory on Optimal Design, Devices and Advanced Materials, Department of Mathematics and Physics, ITESO, Jalisco, Mexico
| | - Nereida Ibarra-Castañeda
- Laboratory of Neuroscience, School of Psychology, University of Colima, Colima, Mexico; Medical Science PhD Program, School of Medicine, University of Colima, Colima, Mexico
| | - Jonathan Buriticá
- Centro de Estudios e Investigaciones en Comportamiento, University of Guadalajara, Jalisco, Mexico
| | - Óscar González-Pérez
- Laboratory of Neuroscience, School of Psychology, University of Colima, Colima, Mexico.
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Kryszkowski W, Boczek T. The G Protein-Coupled Glutamate Receptors as Novel Molecular Targets in Schizophrenia Treatment-A Narrative Review. J Clin Med 2021; 10:jcm10071475. [PMID: 33918323 PMCID: PMC8038150 DOI: 10.3390/jcm10071475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/24/2021] [Accepted: 03/28/2021] [Indexed: 12/02/2022] Open
Abstract
Schizophrenia is a severe neuropsychiatric disease with an unknown etiology. The research into the neurobiology of this disease led to several models aimed at explaining the link between perturbations in brain function and the manifestation of psychotic symptoms. The glutamatergic hypothesis postulates that disrupted glutamate neurotransmission may mediate cognitive and psychosocial impairments by affecting the connections between the cortex and the thalamus. In this regard, the greatest attention has been given to ionotropic NMDA receptor hypofunction. However, converging data indicates metabotropic glutamate receptors as crucial for cognitive and psychomotor function. The distribution of these receptors in the brain regions related to schizophrenia and their regulatory role in glutamate release make them promising molecular targets for novel antipsychotics. This article reviews the progress in the research on the role of metabotropic glutamate receptors in schizophrenia etiopathology.
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Affiliation(s)
- Waldemar Kryszkowski
- General Psychiatric Ward, Babinski Memorial Hospital in Lodz, 91229 Lodz, Poland;
| | - Tomasz Boczek
- Department of Molecular Neurochemistry, Medical University of Lodz, 92215 Lodz, Poland
- Correspondence:
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Crossin R, Qama A, Andrews ZB, Lawrence AJ, Duncan JR. The effect of adolescent inhalant abuse on energy balance and growth. Pharmacol Res Perspect 2019; 7:e00498. [PMID: 31384470 PMCID: PMC6664821 DOI: 10.1002/prp2.498] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/21/2019] [Accepted: 05/25/2019] [Indexed: 12/20/2022] Open
Abstract
The abuse of volatile solvents such as toluene is a significant public health concern, predominantly affecting adolescents. To date, inhalant abuse research has primarily focused on the central nervous system; however, inhalants also exert effects on other organ systems and processes, including metabolic function and energy balance. Adolescent inhalant abuse is characterized by a negative energy balance phenotype, with the peak period of abuse overlapping with the adolescent growth spurt. There are multiple components within the central and peripheral regulation of energy balance that may be affected by adolescent inhalant abuse, such as impaired metabolic signaling, decreased food intake, altered dietary preferences, disrupted glucose tolerance and insulin release, reduced adiposity and skeletal density, and adrenal hypertrophy. These effects may persist into abstinence and adulthood, and the long-term consequences of inhalant-induced metabolic dysfunction are currently unknown. The signs and symptoms resulting from chronic adolescent inhalant abuse may result in a propensity for the development of adult-onset metabolic disorders such as type 2 diabetes, however, further research investigating the long-term effects of inhalant abuse upon energy balance and metabolism are needed. This review addresses several aspects of the short- and long-term effects of inhalant abuse relating to energy and metabolic processes, including energy balance, intake and expenditure; dietary preferences and glycemic control; and the dysfunction of metabolic homeostasis through altered adipose tissue, bone, and hypothalamic-pituitary-adrenal axis function.
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Affiliation(s)
- Rose Crossin
- Florey Institute of Neuroscience and Mental HealthParkvilleVIC
- Turning Point, Eastern HealthRichmondVIC
- Eastern Health Clinical SchoolMonash UniversityBox HillVIC
| | - Ashleigh Qama
- Florey Institute of Neuroscience and Mental HealthParkvilleVIC
- WHO Collaborating Centre for Viral HepatitisPeter Doherty Institute for Infection and ImmunityMelbourneVIC
| | - Zane B. Andrews
- Monash Biomedicine Discovery InstituteMonash UniversityClaytonVIC
| | - Andrew J. Lawrence
- Florey Institute of Neuroscience and Mental HealthParkvilleVIC
- Florey Department of Neuroscience and Mental HealthUniversity of MelbourneParkvilleVIC
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Attenuation of toluene-induced brain stimulation reward enhancement and behavioral disturbances by N-acetylcysteine in mice. Toxicology 2018; 408:39-45. [DOI: 10.1016/j.tox.2018.06.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 06/04/2018] [Accepted: 06/20/2018] [Indexed: 12/21/2022]
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Malloul H, Bennis M, Ba-M'hamed S. Positive reinforcement and c-Fos expression following abuse-like thinner inhalation in mice: Behavioural and immunohistochemical assessment. Eur J Neurosci 2018; 48:2182-2198. [PMID: 30070747 DOI: 10.1111/ejn.14095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 07/01/2018] [Accepted: 07/18/2018] [Indexed: 01/11/2023]
Abstract
Thinners are organic solvents widely used in industrial applications, but they have also been subject to abuse by inhalation for their psychoactive and rewarding properties. In spite of the prevalence of inhalant abuse, the addictive potential and pathways mediating their reinforcing effects are not yet fully understood and thus still subject of further investigations. Here, we assessed in mice the locomotor activity and the ability of paint thinner to reinforce the conditioning in the place preference paradigm following acute (1 day), subchronic (6 weeks) and chronic (12 weeks) exposures to 300 and 600 ppm of thinner vapor. While locomotor activity was unaffected by the different thinner treatments, a positive conditioned place preference to inhaled thinner was found upon subchronic and chronic exposures. To investigate the activated brain structures underlying such behavioural changes, we analyzed the distribution of c-Fos immunoreactivity, a marker for neuronal activation, following acute and repeated exposures to 600 ppm of thinner. Notably, thinner exposure increased the number of c-Fos immunoreactive neurons with increasing duration of exposure in the majority of structures examined; including those typically involved in the processing of rewarding or emotionally stimuli (e.g., ventral tegmental area, core and shell of nucleus accumbens, amygdala, bed nucleus of the stria terminalis, and cingulate cortex), and olfactory stimuli (e.g., piriform cortex and olfactory tubercle). Moreover, prolonged, but not acute thinner inhalation significantly increased c-Fos immunoreactivity in all hippocampal subregions. Taken together, the expanded distribution of thinner-induced c-Fos expression may underlie the observed positive reinforcement upon long-term thinner inhalation.
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Affiliation(s)
- Hanaa Malloul
- Laboratory of Pharmacology, Neurobiology and Behavior (URAC-37), Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech, Morocco
| | - Mohammed Bennis
- Laboratory of Pharmacology, Neurobiology and Behavior (URAC-37), Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech, Morocco
| | - Saadia Ba-M'hamed
- Laboratory of Pharmacology, Neurobiology and Behavior (URAC-37), Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech, Morocco
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Toluene inhalation exposure for 13 weeks causes persistent changes in electroretinograms of Long-Evans rats. Neurotoxicology 2016; 53:257-270. [PMID: 26899397 DOI: 10.1016/j.neuro.2016.02.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 02/12/2016] [Accepted: 02/15/2016] [Indexed: 11/22/2022]
Abstract
Studies of humans chronically exposed to volatile organic solvents have reported impaired visual functions, including low contrast sensitivity and reduced color discrimination. These reports, however, lacked confirmation from controlled laboratory experiments. To address this question experimentally, we examined visual function by recording visual evoked potentials (VEP) and/or electroretinograms (ERG) from four sets of rats exposed repeatedly to toluene. In addition, eyes of the rats were examined with an ophthalmoscope and some of the retinal tissues were evaluated for rod and M-cone photoreceptor immunohistochemistry. The first study examined rats following exposure to 0, 10, 100 or 1000ppm toluene by inhalation (6hr/d, 5d/wk) for 13 weeks. One week after the termination of exposure, the rats were implanted with chronically indwelling electrodes and the following week pattern-elicited VEPs were recorded. VEP amplitudes were not significantly changed by toluene exposure. Four to five weeks after completion of exposure, rats were dark-adapted overnight, anesthetized, and several sets of electroretinograms (ERG) were recorded. In dark-adapted ERGs recorded over a 5-log (cd-s/m(2)) range of flash luminance, b-wave amplitudes were significantly reduced at high stimulus luminance values in rats previously exposed to 1000ppm toluene. A second set of rats, exposed concurrently with the first set, was tested approximately one year after the termination of 13 weeks of exposure to toluene. Again, dark-adapted ERG b-wave amplitudes were reduced at high stimulus luminance values in rats previously exposed to 1000ppm toluene. A third set of rats was exposed to the same concentrations of toluene for only 4 weeks, and a fourth set of rats exposed to 0 or 1000ppm toluene for 4 weeks were tested approximately 1year after the completion of exposure. No statistically significant reductions of ERG b-wave amplitude were observed in either set of rats exposed for 4 weeks. No significant changes were observed in ERG a-wave amplitude or latency, b-wave latency, UV- or green-flicker ERGs, or in photopic flash ERGs. There were no changes in the density of rod or M-cone photoreceptors. The ERG b-wave reflects the firing patterns of on-bipolar cells. The reductions of b-wave amplitude after 13 weeks of exposure and persisting for 1year suggest that alterations may have occurred in the inner nuclear layer of the retina, where the bipolar cells reside, or the outer or inner plexiform layers where the bipolar cells make synaptic connections. These data provide experimental evidence that repeated exposure to toluene may lead to subtle persistent changes in visual function. The fact that toluene affected ERGs, but not VEPs, suggests that elements in the rat retina may be more sensitive to organic solvent exposure than the rat visual cortex.
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mGlu2 Receptor Agonism, but Not Positive Allosteric Modulation, Elicits Rapid Tolerance towards Their Primary Efficacy on Sleep Measures in Rats. PLoS One 2015; 10:e0144017. [PMID: 26658273 PMCID: PMC4684355 DOI: 10.1371/journal.pone.0144017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 11/12/2015] [Indexed: 12/17/2022] Open
Abstract
G-protein-coupled receptor (GPCR) agonists are known to induce both cellular adaptations resulting in tolerance to therapeutic effects and withdrawal symptoms upon treatment discontinuation. Glutamate neurotransmission is an integral part of sleep-wake mechanisms, which processes have translational relevance for central activity and target engagement. Here, we investigated the efficacy and tolerance potential of the metabotropic glutamate receptors (mGluR2/3) agonist LY354740 versus mGluR2 positive allosteric modulator (PAM) JNJ-42153605 on sleep-wake organisation in rats. In vitro, the selectivity and potency of JNJ-42153605 were characterized. In vivo, effects on sleep measures were investigated in rats after once daily oral repeated treatment for 7 days, withdrawal and consecutive re-administration of LY354740 (1–10 mg/kg) and JNJ-42153605 (3–30 mg/kg). JNJ-42153605 showed high affinity, potency and selectivity at mGluR2. Binding site analyses and knowledge-based docking confirmed the specificity of JNJ-42153605 at the mGluR2 allosteric binding site. Acute LY354740 and JNJ-42153605 dose-dependently decreased rapid eye movement (REM) sleep time and prolonged its onset latency. Sub chronic effects of LY354740 on REM sleep measures disappeared from day 3 onwards, whereas those of JNJ-42153605 were maintained after repeated exposure. LY354740 attenuated REM sleep homeostatic recovery, while this was preserved after JNJ-42153605 administration. JNJ-42153605 enhanced sleep continuity and efficiency, suggesting its potential as an add-on medication for impaired sleep quality during early stages of treatment. Abrupt cessation of JNJ-42153605 did not induce withdrawal phenomena and sleep disturbances, while the initial drug effect was fully reinstated after re-administration. Collectively, long-term treatment with JNJ-42153605 did not induce tolerance phenomena to its primary functional effects on sleep measures, nor adverse effects at withdrawal, while it promoted homeostatic recovery sleep. From the translational perspective, the present rodent findings suggest that mGluR2 positive allosteric modulation has therapeutic potential based on its superior long term efficacy over agonists in psychiatric disorders, particularly of those commonly occurring with REM sleep overdrive.
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11
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The group II metabotropic glutamate receptor agonist LY379268 reduces toluene-induced enhancement of brain-stimulation reward and behavioral disturbances. Psychopharmacology (Berl) 2015; 232:3259-68. [PMID: 26044619 PMCID: PMC4536139 DOI: 10.1007/s00213-015-3973-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 05/24/2015] [Indexed: 01/05/2023]
Abstract
RATIONALE Toluene, a widely abused solvent with demonstrated addictive potential in humans, hasbeen reported to negatively modulate N-methyl-D-aspartate receptors (NMDARs) and alter glutamatergicneurotransmission. The group II metabotropic glutamate receptor (mGluR) agonist LY379268 has beenshown to regulate glutamate release transmission and NMDAR function and block toluene-induced locomotorhyperactivity. However, remaining unknown is whether group II mGluRs are involved in the toluene-induced reward-facilitating effect and other behavioral manifestations. OBJECTIVES The present study evaluated the effects of LY379268 on toluene-induced reward enhancement, motor incoordination, recognition memory impairment, and social interaction deficits. RESULTS Our data demonstrated that LY379268 significantly reversed the toluene-induced lowering of intracranial self-stimulation (ICSS) thresholds and impairments in novel object recognition, rotarod performance, and social interaction with different potencies. CONCLUSIONS These results indicate a negative modulatory role of group II mGluRs in acute toluene-induced reward-facilitating and behavioral effects and suggest that group II mGluR agonists may have therapeutic potential for toluene addiction and the prevention of toluene intoxication caused by occupational or intentional exposure.
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12
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Apawu AK, Mathews TA, Bowen SE. Striatal dopamine dynamics in mice following acute and repeated toluene exposure. Psychopharmacology (Berl) 2015; 232:173-84. [PMID: 24994552 DOI: 10.1007/s00213-014-3651-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 06/02/2014] [Indexed: 02/02/2023]
Abstract
RATIONALE The abused inhalant toluene has potent behavioral effects, but only recently has progress been made in understanding the neurochemical actions that mediate the action of toluene in the brain. Available evidence suggests that toluene inhalation alters dopamine (DA) neurotransmission, but toluene's mechanism of action is unknown. OBJECTIVE The present study evaluated the effect of acute and repeated toluene inhalation (0, 2,000, or 4,000 ppm) on locomotor activity as well as striatal DA release and uptake using slice fast-scan cyclic voltammetry. RESULTS Acutely, 2,000 and 4,000 ppm toluene increased locomotor activity, while neurochemically only 4,000 ppm toluene potentiated electrically evoked DA release across the caudate-putamen and the nucleus accumbens. Repeated administration of toluene resulted in sensitization to toluene's locomotor activity effects. Brain slices obtained from mice repeatedly exposed to toluene demonstrated no difference in stimulated DA release in the caudate-putamen as compared to control animals. Repeated exposure to 2,000 and 4,000 ppm toluene caused a concentration-dependent decrease of 25-50 % in evoked DA release in the nucleus accumbens core and shell relative to air-exposed mice. CONCLUSIONS These voltammetric neurochemical findings following repeated toluene exposure suggest that there may be a compensatory downregulation of the DA system. Acute or repeated toluene exposure had no effect on the DA uptake kinetics. Taken together, these results demonstrate that acute toluene inhalation potentiates DA release, while repeated toluene exposure attenuates DA release in the nucleus accumbens only.
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Affiliation(s)
- Aaron K Apawu
- Department of Chemistry, Wayne State University, 5101 Cass Ave, Detroit, MI, 48202, USA
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13
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Dick ALW, Lawrence AJ, Duncan JR. Chronic intermittent toluene inhalation initiated during adolescence in rats does not alter voluntary consumption of ethanol in adulthood. Alcohol 2014; 48:561-9. [PMID: 25212750 DOI: 10.1016/j.alcohol.2014.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Voluntary inhalation of organic solvents, such as toluene, is particularly prevalent in adolescent populations and is considered to be a contributing factor to substance use and dependence later in life. While inhalants are often the initial "drug" experienced during this period, alcohol is another substance readily abused by adolescent populations. Although both substances are thought to have similar actions within the brain, our understanding of the implications of adolescent inhalant abuse upon subsequent exposure to alcohol remains to be investigated. Thus, this study aimed to assess locomotor responses to acute ethanol and voluntary ethanol consumption following a period of toluene inhalation throughout adolescence/early adulthood. Adolescent male Wistar rats (postnatal day [PN] 27) inhaled air or toluene (3000 ppm) for 1 h/day, 3 days/week for 4 (PN 27-52) or 8 weeks (PN 27-80) to mimic the patterns observed in human inhalant abusers. Following the exposure period, cross-sensitization to acute ethanol challenge (0.5 g/kg, intra-peritoneally [i.p.]), and voluntary consumption of 20% ethanol in a chronic intermittent 2-bottle choice paradigm, were assessed. Hepatic ethanol and acetaldehyde metabolism and liver histopathology were also investigated. Chronic intermittent toluene (CIT) exposure throughout adolescence for up to 8 weeks did not alter the behavioral response to acute ethanol or voluntary consumption of ethanol in adulthood, although an age-dependent effect on ethanol consumption was observed (p<0.05). Both liver function and pathology did not differ between treatment groups. Thus, in the paradigm employed, CIT exposure throughout adolescence and early adulthood did not predispose rats to subsequent locomotor sensitivity or voluntary consumption of ethanol in adulthood.
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Affiliation(s)
- Alec L W Dick
- Florey Institute of Neuroscience & Mental Health, Australia; Florey Department of Neuroscience and Mental Health, Australia
| | - Andrew J Lawrence
- Florey Institute of Neuroscience & Mental Health, Australia; Florey Department of Neuroscience and Mental Health, Australia.
| | - Jhodie R Duncan
- Florey Institute of Neuroscience & Mental Health, Australia; Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Victoria 3010 Australia.
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Fifel K, Bennis M, Ba-M'hamed S. Effects of acute and chronic inhalation of paint thinner in mice: behavioral and immunohistochemical study. Metab Brain Dis 2014; 29:471-82. [PMID: 24218105 DOI: 10.1007/s11011-013-9449-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 10/30/2013] [Indexed: 12/26/2022]
Abstract
Abuse of volatile inhalants has become a worldwide issue mainly among adolescents of low income social class. Acute and chronic exposure to these substances results in serious neurological and behavioral impairments. Although real exposure consists largely of simultaneous inhalation of multiple solvents, the vast majority of basic research studies have evaluated the actions of a single volatile component leaving the behavioral and neuronal effects of chemical mixture not fully understood. In this study, we investigated the acute behavioral effects of 300, 450 and 600 ppm of paint thinner inhalation on anxiety, locomotor activity and spatial memory. Additionally, the cognitive impairments related to chronic exposure of the same concentrations of thinner for 45 days were assessed. To understand the neuronal correlates of acute exposure to thinner, we used c-Fos immunohistochemistry as an endogenous marker of neuronal activation following 600 ppm of thinner. The results reveal that (i) chronically thinner exposed mice showed cognitive deficits in Morris water maze and object recognition tasks; (ii) acute inhalation of thinner induces a wide range of behavioral changes. These changes include an anxiolytic effect toward the aversive environmental bright light and a dose dependent effect on explorative locomotion. The wide range of behavioral alterations induced by acute thinner inhalation is consistent with the widespread distribution of thinner-induced c-Fos expression in multiple brain structures.
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Affiliation(s)
- Karim Fifel
- Lab of Pharmacology, Neurobiology and Behavior, Associated CNRST Unit (URAC-37), Cadi Ayyad University, Marrakech, Morocco,
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15
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Beckley JT, Woodward JJ. Volatile solvents as drugs of abuse: focus on the cortico-mesolimbic circuitry. Neuropsychopharmacology 2013; 38:2555-67. [PMID: 23954847 PMCID: PMC3828545 DOI: 10.1038/npp.2013.206] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/12/2013] [Accepted: 08/13/2013] [Indexed: 12/15/2022]
Abstract
Volatile solvents such as those found in fuels, paints, and thinners are found throughout the world and are used in a variety of industrial applications. However, these compounds are also often intentionally inhaled at high concentrations to produce intoxication. While solvent use has been recognized as a potential drug problem for many years, research on the sites and mechanisms of action of these compounds lags behind that of other drugs of abuse. In this review, we first discuss the epidemiology of voluntary solvent use throughout the world and then consider what is known about their basic pharmacology and how this may explain their use as drugs of abuse. We next present data from preclinical and clinical studies indicating that these substances induce common addiction sequelae such as dependence, withdrawal, and cognitive impairments. We describe how toluene, the most commonly studied psychoactive volatile solvent, alters synaptic transmission in key brain circuits such as the mesolimbic dopamine system and medial prefrontal cortex (mPFC) that are thought to underlie addiction pathology. Finally, we make the case that activity in mPFC circuits is a critical regulator of the mesolimbic dopamine system's ability to respond to volatile solvents like toluene. Overall, this review provides evidence that volatile solvents have high abuse liability because of their selective effects on critical nodes of the addiction neurocircuitry, and underscores the need for more research into how these compounds induce adaptations in neural circuits that underlie addiction pathology.
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Affiliation(s)
- Jacob T Beckley
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA,Center for Drug and Alcohol Programs, Department of Psychiatry/Neurosciences, Medical University of South Carolina, Charleston, SC, USA
| | - John J Woodward
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA,Center for Drug and Alcohol Programs, Department of Psychiatry/Neurosciences, Medical University of South Carolina, Charleston, SC, USA,Department of Neurosciences, Medical University of South Carolina, IOP 4 North, 67 President Street, MSC 861, Charleston, SC 29425, USA, Tel: +(843) 792 5225, Fax: +(843) 792 7353, E-mail:
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Samuel-Herter SR, Slaght SL, McKay BE. Age-dependent time courses of recovery for motor functions following acute toluene intoxication in rats. Dev Psychobiol 2013; 56:657-73. [PMID: 23765908 DOI: 10.1002/dev.21134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Accepted: 04/12/2013] [Indexed: 12/13/2022]
Abstract
Toluene is a psychoactive chemical found in many household products including adhesives and thinners. Inhalation of these vapors can cause euphoria and impairments in motor control and neurological functioning. Misuse and abuse of toluene is most common in children, which may in part be due to an age-dependent neurobehavioral sensitivity to toluene. Here we assessed the effects of acute binge-like toluene inhalations (15 or 30 min; ∼5,000 ppm) on tasks that examine locomotion, exploration, balance, gait, and neurological functioning for adolescent (1 month), young adult (2-3 months), adult (5-6 months), and older adult (10-12 months) rats. Both motor and neurological functions were impaired following acute toluene inhalation at all ages. However, only the duration to recover from deficits in motor functions differed among age groups, with adolescent and young adult rats requiring notably longer recovery times than older rats. Our results are suggestive of an age-dependent vulnerability to the intoxicating effects of toluene.
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Affiliation(s)
- Susan R Samuel-Herter
- Department of Psychology, Wilfrid Laurier University, 75 University Ave W., Waterloo, Ontario, Canada, N2L 3C5
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Duncan JR, Lawrence AJ. Conventional Concepts and New Perspectives for Understanding the Addictive Properties of Inhalants. J Pharmacol Sci 2013; 122:237-43. [DOI: 10.1254/jphs.13r04cp] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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18
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Volatile substance misuse : clinical considerations, neuropsychopharmacology and potential role of pharmacotherapy in management. CNS Drugs 2012; 26:927-35. [PMID: 23018545 DOI: 10.1007/s40263-012-0001-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Volatile substance misuse is among the most prevalent and toxic forms of psychoactive drug use, and often results in highly deleterious social, psychological and medical consequences. The prevalence of this pernicious form of substance misuse owes in part to the fact that volatile substances of misuse are ubiquitous in the natural environment. Commonly misused commercial products include glue, shoe polish, nail polish remover, butane lighter fluid, gasoline and computer duster spray. National samples of volatile substance misusers tend to exhibit high rates of psychiatric problems and antisocial behaviour. In addition, cognitive impairments and affective dysregulation are often observed among these individuals. Volatile substances exert their complex neuropharmacological effects on dopaminergic, glutamatergic, GABAergic and serotoninergic receptor systems, as well as on cell membranes and ion channels. Concomitantly, pharmacotherapies for volatile substance abuse might profitably target a number of mechanisms, including reward circuitry in the brain, symptoms of craving and withdrawal, neuropsychiatric and emotional impairments that promote volatile substance abuse, and cognitive enhancement to rectify deficits in executive function. This review details the modes of use, subjective effects, epidemiology, adverse consequences, neuropsychopharmacology and drug treatment of volatile substance misuse, and discusses the potential role of novel forms of pharmacological intervention for this oft-overlooked public health threat of epidemic proportions.
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Chan MH, Chung SS, Stoker AK, Markou A, Chen HH. Sarcosine attenuates toluene-induced motor incoordination, memory impairment, and hypothermia but not brain stimulation reward enhancement in mice. Toxicol Appl Pharmacol 2012; 265:158-65. [PMID: 23067721 DOI: 10.1016/j.taap.2012.10.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 10/03/2012] [Accepted: 10/05/2012] [Indexed: 12/22/2022]
Abstract
Toluene, a widely used and commonly abused organic solvent, produces various behavioral disturbances, including motor incoordination and cognitive impairment. Toluene alters the function of a large number of receptors and ion channels. Blockade of N-methyl-d-aspartate (NMDA) receptors has been suggested to play a critical role in toluene-induced behavioral manifestations. The present study determined the effects of various toluene doses on motor coordination, recognition memory, body temperature, and intracranial self-stimulation (ICSS) thresholds in mice. Additionally, the effects of sarcosine on the behavioral and physiological effects induced by toluene were evaluated. Sarcosine may reverse toluene-induced behavioral manifestations by acting as an NMDA receptor co-agonist and by inhibiting the effects of the type I glycine transporter (GlyT1). Mice were treated with toluene alone or combined with sarcosine pretreatment and assessed for rotarod performance, object recognition memory, rectal temperature, and ICSS thresholds. Toluene dose-dependently induced motor incoordination, recognition memory impairment, and hypothermia and lowered ICSS thresholds. Sarcosine pretreatment reversed toluene-induced changes in rotarod performance, novel object recognition, and rectal temperature but not ICSS thresholds. These findings suggest that the sarcosine-induced potentiation of NMDA receptors may reverse motor incoordination, memory impairment, and hypothermia but not the enhancement of brain stimulation reward function associated with toluene exposure. Sarcosine may be a promising compound to prevent acute toluene intoxications by occupational or intentional exposure.
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Affiliation(s)
- Ming-Huan Chan
- Department of Pharmacology and Toxicology, Tzu Chi University, Hualien, Taiwan
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20
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Metabotropic glutamate receptor 5 modulates behavioral and hypothermic responses to toluene in rats. Pharmacol Biochem Behav 2012; 103:418-24. [PMID: 23026060 DOI: 10.1016/j.pbb.2012.09.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 09/21/2012] [Accepted: 09/24/2012] [Indexed: 11/23/2022]
Abstract
Toluene, a widely used and commonly abused organic solvent, produces various behavioral disturbances in both humans and animals. Blockade of N-methyl-d-aspartate (NMDA) receptors has been suggested to play a critical role in acute toluene-induced behavioral manifestations. Activation of type 5 metabotropic glutamate receptors (mGluR5) attenuates behavioral responses induced by NMDA receptor blockade. The present study elucidated the role of mGluR5 on toluene-induced behavioral and hypothermic responses. Male Sprague-Dawley rats received the mGluR5 agonist (RS)-2-chloro-5-hydroxyphenylglycine (CHPG) or antagonist 6-methyl-2-[phenylethynyl]-pyridine (MPEP) prior to toluene administration. Rotarod test, step-down inhibitory avoidance learning task, and rectal temperature were monitored. Pretreatment of CHPG and MPEP attenuated and potentiated these toluene-induced responses, respectively. In addition, the inhibitory effects of CHPG on toluene-induced motor incoordination, learning impairment, and hypothermia were reversed by the protein kinase C (PKC) inhibitor chelerythrine chloride. These findings suggest that mGluR5 may modulate the neural circuits responsible for motor incoordination, learning impairment, and hypothermic action of toluene through a PKC-dependent signal transduction pathway.
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21
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Adolescent toluene inhalation in rats affects white matter maturation with the potential for recovery following abstinence. PLoS One 2012; 7:e44790. [PMID: 23028622 PMCID: PMC3445546 DOI: 10.1371/journal.pone.0044790] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 08/13/2012] [Indexed: 12/16/2022] Open
Abstract
Inhalant misuse is common during adolescence, with ongoing chronic misuse associated with neurobiological and cognitive abnormalities. While human imaging studies consistently report white matter abnormalities among long-term inhalant users, longitudinal studies have been lacking with limited data available regarding the progressive nature of such abnormalities, including the potential for recovery following periods of sustained abstinence. We exposed adolescent male Wistar rats (postnatal day 27) to chronic intermittent inhaled toluene (3,000 ppm) for 1 hour/day, 3 times/week for 8 weeks to model abuse patterns observed in adolescent and young adult human users. This dosing regimen resulted in a significant retardation in weight gain during the exposure period (p<0.05). In parallel, we performed longitudinal magnetic resonance imaging (T₂-weighted) and diffusion tensor imaging prior to exposure, and after 4 and 8 weeks, to examine the integrity of white matter tracts, including the anterior commissure and corpus callosum. We also conducted imaging after 8 weeks of abstinence to assess for potential recovery. Chronic intermittent toluene exposure during adolescence and early adulthood resulted in white matter abnormalities, including a decrease in axial (p<0.05) and radial (p<0.05) diffusivity. These abnormalities appeared region-specific, occurring in the anterior commissure but not the corpus callosum and were not present until after at least 4 weeks of exposure. Toluene-induced effects on both body weight and white matter parameters recovered following abstinence. Behaviourally, we observed a progressive decrease in rearing activity following toluene exposure but no difference in motor function, suggesting cognitive function may be more sensitive to the effects of toluene. Furthermore, deficits in rearing were present by 4 weeks suggesting that toluene may affect behaviour prior to detectable white matter abnormalities. Consequently, exposure to inhalants that contain toluene during adolescence and early adulthood appear to differentially affect white matter maturation and behavioural outcomes, although recovery can occur following abstinence.
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Conti AC, Lowing JL, Susick LL, Bowen SE. Investigation of calcium-stimulated adenylyl cyclases 1 and 8 on toluene and ethanol neurobehavioral actions. Neurotoxicol Teratol 2012; 34:481-8. [PMID: 22789433 DOI: 10.1016/j.ntt.2012.06.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 06/25/2012] [Accepted: 06/29/2012] [Indexed: 11/26/2022]
Abstract
The abused inhalant toluene has potent behavioral effects, but only recently has progress been made in understanding the molecular pathways that mediate the action of toluene in the brain. Toluene and ethanol induce similar behavioral effects and share some targets including NMDA and GABA receptors. In studies examining neuronal actions of ethanol, mice lacking the calcium-stimulated adenylyl cyclases (ACs), AC1 and AC8 (DKO), show increased sedation durations and impaired protein kinase A (PKA) phosphorylation following acute ethanol treatment. Therefore, using DKO mice, we compared the neurobehavioral responses following toluene exposure to that of ethanol exposure to determine if these abused substances share molecular mechanisms of action. In the present study, acute sensitivity to toluene- or ethanol-induced changes in locomotor activity was evaluated in DKO and wild type (WT) mice. Mice were exposed to toluene vapor (0, 500, 1000, 2000, 6000, or 8000ppm) for 30min in static exposure chambers equipped with activity monitors. Both WT and DKO mice demonstrated increased ambulatory distance during exposure to a 2000-ppm concentration of toluene compared to respective air-exposed (0ppm) controls. Significant increases in locomotor activity were also observed during an air-only recovery period following toluene exposure in WT and DKO mice that had been exposed to 2000ppm of toluene compared to respective air controls. Sedative effects of toluene were equivalent in WT and DKO mice, both during exposure and afterwards during recovery. Although no significant differences in locomotor activity were detected in DKO compared to WT mice at individual doses tested, a significant main effect of toluene was achieved, with DKO mice demonstrating a generalized reduction in locomotor activity during the post-toluene recovery period compared to WT mice (when analyzing all doses collectively). For comparison to toluene, additional WT and DKO mice were treated with 1.0 or 2.0g/kg ethanol (i.p.) and monitored for locomotor activation. In WT mice, both doses of ethanol increased distance traveled compared to saline controls. Conversely, DKO mice demonstrated no increase in locomotor activation at 1.0g/kg, with significantly reduced distances traveled at both doses compared to ethanol-treated WT mice. These behavioral activity results suggest that acute effects of ethanol and toluene are distinct in the mechanisms by which they induce acute sedating effects with respect to AC1 and AC8 activity, but may be similar in the mechanisms subserving locomotor stimulation.
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Affiliation(s)
- Alana C Conti
- John D. Dingell VA Medical Center, Detroit, MI 48201, USA.
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23
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Huerta-Rivas A, López-Rubalcava C, Sánchez-Serrano SL, Valdez-Tapia M, Lamas M, Cruz SL. Toluene impairs learning and memory, has antinociceptive effects, and modifies histone acetylation in the dentate gyrus of adolescent and adult rats. Pharmacol Biochem Behav 2012; 102:48-57. [DOI: 10.1016/j.pbb.2012.03.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 03/14/2012] [Accepted: 03/24/2012] [Indexed: 12/18/2022]
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Davies AG, Friedberg RI, Gupta H, Chan CL, Shelton KL, Bettinger JC. Different genes influence toluene- and ethanol-induced locomotor impairment in C. elegans. Drug Alcohol Depend 2012; 122:47-54. [PMID: 21945072 PMCID: PMC3260412 DOI: 10.1016/j.drugalcdep.2011.08.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 08/12/2011] [Accepted: 08/31/2011] [Indexed: 01/25/2023]
Abstract
BACKGROUND The abused volatile solvent toluene shares many behavioral effects with classic central nervous system depressants such as ethanol. Similarities between toluene and ethanol have also been demonstrated using in vitro electrophysiology. Together, these studies suggest that toluene and ethanol may be acting, at least in part, via common mechanisms. METHODS We used the genetic model, Caenorhabditis elegans, to examine the behavioral effects of toluene in a simple system, and used mutant strains known to have altered responses to other CNS depressants to examine the involvement of those genes in the motor effects induced by toluene. RESULTS Toluene vapor brings about an altered pattern of locomotion in wild-type worms that is visibly distinct from that generated by ethanol. Mutants of the slo-1, rab-3 and unc-64 genes that are resistant to ethanol or the volatile anesthetic halothane show no resistance to toluene. A mutation in the unc-79 gene results in hypersensitivity to ethanol, halothane and toluene indicating a possible convergence of mechanisms of the three compounds. We screened for, and isolated, two mutations that generate resistance to the locomotor depressing effects of toluene and do not alter sensitivity to ethanol. CONCLUSIONS In C. elegans, ethanol and toluene have distinct behavioral effects and minimal overlap in terms of the genes responsible for these effects. These findings demonstrate that the C. elegans model system provides a unique and sensitive means of delineating both the commonalities as well as the differences in the neurochemical effects of classical CNS depressants and abused volatile inhalants.
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Affiliation(s)
- Andrew G. Davies
- Department of Pharmacology and Toxicology, Virginia Commonwealth University Richmond, VA 23298-0613 USA,Department of Psychiatry, Virginia Commonwealth University Richmond, VA 23298-0613 USA,Institute for Drug and Alcohol Studies, Virginia Commonwealth University Richmond, VA 23298-0613 USA,Virginia Commonwealth University – Alcohol Research Center Virginia Commonwealth University Richmond, VA 23298-0613 USA,Corresponding author Andrew G. Davies, Ph.D. Department of Pharmacology and Toxicology Virginia Commonwealth University P.O. Box 980613 Richmond VA, 23298-0613 (804) 828-2068 (w) (804) 828-4794 (fax)
| | - Ryan I. Friedberg
- Department of Pharmacology and Toxicology, Virginia Commonwealth University Richmond, VA 23298-0613 USA
| | - Hersh Gupta
- Department of Pharmacology and Toxicology, Virginia Commonwealth University Richmond, VA 23298-0613 USA
| | - Chung-Lung Chan
- Department of Pharmacology and Toxicology, Virginia Commonwealth University Richmond, VA 23298-0613 USA
| | - Keith L. Shelton
- Department of Pharmacology and Toxicology, Virginia Commonwealth University Richmond, VA 23298-0613 USA,Institute for Drug and Alcohol Studies, Virginia Commonwealth University Richmond, VA 23298-0613 USA
| | - Jill C. Bettinger
- Department of Pharmacology and Toxicology, Virginia Commonwealth University Richmond, VA 23298-0613 USA,Department of Psychiatry, Virginia Commonwealth University Richmond, VA 23298-0613 USA,Institute for Drug and Alcohol Studies, Virginia Commonwealth University Richmond, VA 23298-0613 USA,Virginia Commonwealth University – Alcohol Research Center Virginia Commonwealth University Richmond, VA 23298-0613 USA
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MacPhail RC, Farmer JD, Jarema KA. Toluene effects on the motor activity of adolescent, young-adult, middle-age and senescent male Brown Norway rats. Neurotoxicology 2011; 33:111-8. [PMID: 22192906 DOI: 10.1016/j.neuro.2011.12.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 12/08/2011] [Accepted: 12/08/2011] [Indexed: 11/25/2022]
Abstract
Life stage is an important risk factor for toxicity. Children and aging adults, for example, are more susceptible to certain chemicals than are young adults. In comparison to children, relatively little is known about susceptibility in older adults. Additionally, few studies have compared toxicant susceptibility across a broad range of life stages. Results are presented for behavioral evaluations of male Brown Norway rats obtained as adolescents (1 month), or young (4 months), middle-age (12 months) and senescent (24 months) adults. Motor activity was evaluated in photocell devices during 30-min sessions. Age-related baseline characteristics and sensitivity to toluene (0, 300, 650, or 1000mg/kg, p.o.) were determined. In Experiment 1, young-adult, middle-age and senescent rats were treated with corn-oil vehicle before five weekly test sessions. Baselines of horizontal and vertical activity decreased with age, but each age-group's averages remained stable across weeks of testing. Baseline activity of older rats was more variable than that of the young adults; older rats were also more variable individually from week to week. Toluene (1000mg/kg) increased horizontal activity proportionately more in senescent rats (ca. 300% of control) than in middle-age or young-adult rats (ca.145-175% of control). Experiment 2 established toluene dose-effect functions in individual adolescent, young-adult, middle-age and senescent rats; each rat received all treatments, counterbalanced across four weekly sessions. Toluene produced dose-related increases in horizontal activity that increased proportionately with age. Experiment 3 replicated the effects of toluene (1000mg/kg) in Experiment 1, showing that toluene-induced increases in horizontal activity were greatest in the oldest rats. Collectively, the results show that aging increased susceptibility to toluene and also increased variability in toluene response. Given the rapid growth of the aged population, further research is needed on aging-related susceptibility to environmental contaminants.
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Affiliation(s)
- R C MacPhail
- Neurotoxicology Branch, Toxicity Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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The metabotropic glutamate 2/3 receptor agonist LY379268 blocked nicotine-induced increases in nucleus accumbens shell dopamine only in the presence of a nicotine-associated context in rats. Neuropsychopharmacology 2011; 36:2111-24. [PMID: 21654734 PMCID: PMC3158309 DOI: 10.1038/npp.2011.103] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The metabotropic glutamate 2/3 (mGlu2/3) receptor agonist LY379268 ([-]-2-oxa-4-aminobicyclo [3.1.0] hexane-4,6-dicarboxylate) attenuates both nicotine self-administration and cue-induced nicotine seeking in rats. In this study, the effects of LY379268 (1 mg/kg) or saline pretreatment on nicotine-induced increases in nucleus accumbens (NAcc) shell dopamine were evaluated using in vivo microdialysis under different experimental conditions: (i) nicotine (0.4 mg/kg, base) was experimenter-administered subcutaneously to nicotine-naïve rats; (ii) nicotine was experimenter-administered either subcutaneously (0.4 mg/kg) or by a single experimenter-administered infusion (0.06 mg/kg, base) in rats with a history of nicotine self-administration (nicotine experienced) in the absence of a nicotine-associated context (ie, context and cues associated with nicotine self-administration); (iii) nicotine (0.06 mg/kg) was self-administered or experimenter-administered in nicotine-experienced rats in the presence of a nicotine-associated context. In saline-pretreated nicotine-naïve and nicotine-experienced rats, nicotine increased NAcc shell dopamine regardless of the context used for testing. Interestingly, LY379268 pretreatment blocked nicotine-induced increases in NAcc shell dopamine in nicotine-experienced rats only when tested in the presence of a nicotine-associated context. LY379268 did not block nicotine-induced increases in NAcc shell dopamine in nicotine-naïve or -experienced rats tested in the absence of a nicotine-associated context. These intriguing findings suggest that activation of mGlu2/3 receptors negatively modulates the combined effects of nicotine and nicotine-associated contexts/cues on NAcc dopamine. Thus, these data highlight a critical role for mGlu2/3 receptors in context/cue-induced drug-seeking behavior and suggest a neurochemical mechanism by which mGlu2/3 receptor agonists may promote smoking cessation by preventing relapse induced by the combination of nicotine and nicotine-associated contexts and cues.
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A review of potential neurotoxic mechanisms among three chlorinated organic solvents. Toxicol Appl Pharmacol 2011; 255:113-26. [DOI: 10.1016/j.taap.2011.05.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 05/06/2011] [Accepted: 05/08/2011] [Indexed: 12/17/2022]
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Toluene effects on oxidative stress in brain regions of young-adult, middle-age, and senescent Brown Norway rats. Toxicol Appl Pharmacol 2011; 256:386-98. [PMID: 21549141 DOI: 10.1016/j.taap.2011.04.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 04/12/2011] [Accepted: 04/17/2011] [Indexed: 01/24/2023]
Abstract
The influence of aging on susceptibility to environmental contaminants is not well understood. To extend knowledge in this area, we examined effects in rat brain of the volatile organic compound, toluene. The objective was to test whether oxidative stress (OS) plays a role in the adverse effects caused by toluene exposure, and if so, if effects are age-dependent. OS parameters were selected to measure the production of reactive oxygen species (NADPH Quinone oxidoreductase 1 (NQO1), NADH Ubiquinone reductase (UBIQ-RD)), antioxidant homeostasis (total antioxidant substances (TAS), superoxide dismutase (SOD), γ-glutamylcysteine synthetase (γ-GCS), glutathione transferase (GST), glutathione peroxidase (GPX), glutathione reductase (GRD)), and oxidative damage (total aconitase and protein carbonyls). In this study, Brown Norway rats (4, 12, and 24 months) were dosed orally with toluene (0, 0.65 or 1g/kg) in corn oil. Four hours later, frontal cortex, cerebellum, striatum, and hippocampus were dissected, quick frozen on dry ice, and stored at -80°C until analysis. Some parameters of OS were found to increase with age in select brain regions. Toluene exposure also resulted in increased OS in select brain regions. For example, an increase in NQO1 activity was seen in frontal cortex and cerebellum of 4 and 12 month old rats following toluene exposure, but only in the hippocampus of 24 month old rats. Similarly, age and toluene effects on glutathione enzymes were varied and brain-region specific. Markers of oxidative damage reflected changes in oxidative stress. Total aconitase activity was increased by toluene in frontal cortex and cerebellum at 12 and 24 months, respectively. Protein carbonyls in both brain regions and in all age groups were increased by toluene, but step-down analyses indicated toluene effects were statistically significant only in 12month old rats. These results indicate changes in OS parameters with age and toluene exposure resulted in oxidative damage in frontal cortex and cerebellum of 12 month old rats. Although increases in oxidative damage are associated with increases in horizontal motor activity in older rats, further research is warranted to determine if these changes in OS parameters are related to neurobehavioral and neurophysiological effects of toluene in animal models of aging.
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Duncan JR, Lawrence AJ. The role of metabotropic glutamate receptors in addiction: evidence from preclinical models. Pharmacol Biochem Behav 2011; 100:811-24. [PMID: 21443897 DOI: 10.1016/j.pbb.2011.03.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 02/21/2011] [Accepted: 03/16/2011] [Indexed: 11/25/2022]
Abstract
Addiction is a chronic disorder characterised by repeated bouts of drug taking, abstinence and relapse. The addicted state may be in part due to drug-induced neuroadaptations in the mesocorticolimbic and corticostriatal pathways. Recently focus has been on the role of aberrant glutamate transmission and its contribution to the hierarchical control over these systems. This review will expand our current knowledge of the most recent advances that have been made in preclinical animal models that provide evidence that implicate metabotropic glutamate receptors (mGluRs) in contributing to the neuroadaptations pertinent to addiction, as well as the role of Homer proteins in regulating these responses. The recent discovery of receptor mosaics will be discussed which add an additional dimension to the complexity of understanding the mechanism of glutamate mediated behaviours. Finally this review introduces a new area related to glutamatergic responses, namely microRNAs, that may become pivotal in directing our future understanding of how to best target intervention strategies to prevent addictive behaviours.
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Affiliation(s)
- Jhodie R Duncan
- Florey Neuroscience Institutes, University of Melbourne, Parkville, Vic., 3010, Australia.
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Abstract
This work assessed the extent, patterns, attitudes, motivations, and impacts of volatile substance misuse (VSM) among street children in Upper Egypt. In 2009, a 36-item questionnaire was administered to a randomly selected sample of 120 street children aged 10-18 years. Nearly 91% (n = 109) reported misusing products containing volatile substances because they are inexpensive, legal, and easy to acquire. Familial neglect and lack of supervision were the main social motivations reported by street youth for misusing volatile substances. One-third (34.2%, n = 41) reported inhaling "Kolla," a commercial glue; this study identifies its physicochemical, neuropharmacological, and toxicological properties. The study's limitations are noted.
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Affiliation(s)
- Alaaeldin Elkoussi
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Assiut, Assiut, Egypt.
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Batis JC, Hannigan JH, Bowen SE. Differential effects of inhaled toluene on locomotor activity in adolescent and adult rats. Pharmacol Biochem Behav 2010; 96:438-48. [PMID: 20624418 DOI: 10.1016/j.pbb.2010.07.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Revised: 06/28/2010] [Accepted: 07/05/2010] [Indexed: 10/19/2022]
Abstract
Inhalant abuse is a world-wide public health concern among adolescents. Most preclinical studies have assessed inhalant effects in adult animals leaving unclear how behavioral effects differ in younger animals. We exposed adolescent (postnatal day [PN] 28) and adult (PN90) male rats to toluene using 1 of 3 exposure patterns. These patterns modeled those reported in toluene abuse in teens and varied concentration, number and length of exposures, as well as the inter-exposure interval. Animals were exposed repeatedly over 12 days to toluene concentrations of 0, 8000 or 16,000 parts per million (ppm). Locomotor activity was quantified during toluene exposures and for 30 min following completion of the final daily toluene exposure. For each exposure pattern, there were significant toluene concentration-related increases and decreases in locomotor activity compared to the 0-ppm "air" controls at both ages. These changes depended upon when activity was measured - during or following exposure. Compared to adults, adolescents displayed greater locomotor activity on the first day and generally greater increases in activity over days than adults during toluene exposure. Adults displayed greater locomotor activity than adolescents in the "recovery" period following exposure on the first and subsequent days. Age group differences were clearest following the pattern of paced, brief (5-min) repeated binge exposures. The results suggest that locomotor behavior in rats during and following inhalation of high concentrations of toluene depends on age and the pattern of exposure. The results are consistent with dose-dependent shifts in sensitivity and sensitization or tolerance to repeated toluene in the adolescent animals compared to the adult animals. Alternate interpretations are possible and our interpretation is limited by the range of very high concentrations of toluene used. The results imply that both pharmacological and psychosocial factors contribute to the teen prevalence of inhalant abuse.
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Affiliation(s)
- Jeffery C Batis
- Department of Psychology, Wayne State University, Detroit, MI 48202, USA
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Abstract
Toluene is an organic solvent that is widely used by industry and is ubiquitous in our environment. As a result, exposure to solvents like toluene in work-related settings (i.e., relatively constant, low-level exposures) or through inhalant abuse (i.e., relatively intermittent, high-level exposures) is increasing for many women of reproductive age. Evidence suggests that the risk for pregnancy problems, as well as developmental delays and neurobehavioral difficulties, is higher for the children of women who have been exposed to high concentrations of organic solvents during pregnancy than for those who have not. These risks appear to be higher in cases of abuse exposure to solvents such as toluene, particularly in comparison to the risk for teratogenic outcomes with occupational solvent exposure. Despite this, the reproductive toxicology and teratology following abuse of toluene and other inhalants remains under-investigated. This brief review describes the current state of our understanding of the reproductive and teratogenic risk of gestational toluene abuse. The data to date suggest that the high levels of toluene exposure typical with inhalant abuse are more detrimental to fetal development than typical occupational exposure, and preclinical paradigms can be beneficial for investigating the processes and risks of prenatal solvent exposure. While substantial research has been done on the reproductive effects of occupational exposures to organic solvents, more research is needed on the outcomes and mechanisms of exposures typical of inhalant abuse.
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Affiliation(s)
- John H Hannigan
- Merrill Palmer Skillman Institute, Department of Obstetrics & Gynecology, C.S. Mott Center for Human Growth & Development, Wayne State University, Detroit, MI 48202, USA.
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Bowen SE, Kimar S, Irtenkauf S. Comparison of toluene-induced locomotor activity in four mouse strains. Pharmacol Biochem Behav 2010; 95:249-57. [PMID: 20138905 DOI: 10.1016/j.pbb.2010.01.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 01/19/2010] [Accepted: 01/30/2010] [Indexed: 11/18/2022]
Abstract
The mechanisms by which abused inhalants exert their neurobehavioral effects are only partially understood. In research with other drugs of abuse, specific inbred mouse strains have been useful in exploring genetic loci important to variation in behavioral reactions to these drugs. In the present investigation, mice from three inbred strains (Balb/cByj, C57BL/6J and DBA/2J) and one outbred strain (Swiss Webster) were studied for their acute and chronic sensitivity to toluene-induced changes in locomotor activity. Mice were exposed to toluene (0, 100, 2000, 8000, and 10,000 ppm) for 30 min in static exposure chambers equipped with activity monitors. In the acute condition, concentrations of toluene <8000 ppm increased ambulatory distance while the concentrations of > or =8000 ppm induced temporally biphasic effects with initial increases in activity followed by hypoactivity. Between-group differences in absolute locomotor activity levels were evident. The inbred Balb/cByj and DBA/2J strains as well as the outbred Swiss Webster strain of mice showed greater increases in activity after an acute challenge exposure to 2000 ppm than the inbred C57BL/6J strain. The same animals were then exposed 30 min/day to 8000 ppm toluene for 14 consecutive days. Re-determination of responses to 2000-ppm challenge exposures revealed that sensitization developed in locomotor activity and that the DBA/2J strain showed the greatest increase in sensitivity. These baseline differences in acute sensitivity and the differential shifts in sensitivity after repeated exposures among the inbred mouse strains suggest a genetic basis for the behavioral effects to toluene. The results support the notion that like for other drugs of abuse, using various strains of mice may be useful for investigating mechanisms that underlie risk for inhalant abuse.
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Affiliation(s)
- Scott E Bowen
- Department of Psychology, Wayne State University, Detroit, MI, USA.
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Jupp B, Lawrence AJ. New horizons for therapeutics in drug and alcohol abuse. Pharmacol Ther 2010; 125:138-68. [DOI: 10.1016/j.pharmthera.2009.11.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 11/03/2009] [Indexed: 11/25/2022]
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Seo HS, Yang M, Song MS, Kim JS, Kim SH, Kim JC, Kim H, Shin T, Wang H, Moon C. Toluene inhibits hippocampal neurogenesis in adult mice. Pharmacol Biochem Behav 2009; 94:588-94. [PMID: 19969016 DOI: 10.1016/j.pbb.2009.11.015] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2009] [Revised: 11/02/2009] [Accepted: 11/30/2009] [Indexed: 10/20/2022]
Abstract
Toluene, a representative industrial solvent and abused inhalant, decreases neuronal activity in vitro and causes mental depression and cognitive impairment in humans. However, the effects of toluene on brain function and the sites of its action are poorly understood. This study investigated the temporal changes of neurogenesis in the hippocampus of adult C57BL/6 mice after acute administration of toluene using two immunohistochemical markers for neurogenesis, Ki-67 and doublecortin (DCX). In addition, after toluene treatment, depression-like behaviors and learning and memory tasks were examined to assess hippocampal neurogenesis-related behavioral dysfunction. The number of Ki-67- and DCX-positive cells in the dentate gyrus of adult hippocampi declined acutely between 0 h and 24 h after toluene treatment (500 mg/kg, i.p.) and increased gradually from 2 to 8 days post-administration. The level of Ki-67 and DCX immunoreactivity decreased in a dose-dependent manner within the range of toluene administered (0-1000 mg/kg). In tail suspension and forced-swim tests performed at 1 and 4 days after toluene treatment (500 mg/kg), mice showed significant depression-like behaviors compared to the vehicle-treated controls. In the contextual fear conditioning and object recognition memory test, the mice trained at 1 and 4 days after toluene treatment showed significant memory defects compared to the vehicle-treated controls. This study suggests that acute exposure to toluene reduces the rate of adult hippocampal neurogenesis and can cause hippocampal dysfunction such as depression and cognitive impairment.
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Affiliation(s)
- Heung-Sik Seo
- Department of Veterinary Anatomy, College of Veterinary Medicine and Animal Medical Institute, Chonnam National University, Gwangju 500-757, South Korea
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Lo PS, Wu CY, Sue HZ, Chen HH. Acute neurobehavioral effects of toluene: Involvement of dopamine and NMDA receptors. Toxicology 2009; 265:34-40. [DOI: 10.1016/j.tox.2009.09.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 09/10/2009] [Accepted: 09/10/2009] [Indexed: 12/25/2022]
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Cruz SL, Soberanes-Chávez P, Páez-Martinez N, López-Rubalcava C. Toluene has antidepressant-like actions in two animal models used for the screening of antidepressant drugs. Psychopharmacology (Berl) 2009; 204:279-86. [PMID: 19151967 DOI: 10.1007/s00213-009-1462-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Accepted: 12/29/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE Many abused solvents share a profile of effects with classical antidepressants. For example, toluene, which is a representative and widely abused solvent, has been reported to increase both serotonin and noradrenaline levels in several brain areas after an acute exposure and to act as a noncompetitive antagonist of the glutamatergic N-methyl-D-aspartic acid (NMDA) receptor subtype. Therefore, it is possible that toluene could possess antidepressant-like actions. OBJECTIVE To provide an initial screening of toluene's antidepressant-like actions in the forced swimming test (FST) and the tail suspension test (TST) in mice and to analyze its possible mechanism of action. MATERIALS AND METHODS Two series of experiments were performed. In the first one, male animals were exposed to toluene (0, 500, 1,000, 2,000, or 4,000 ppm) in a static exposure chamber for 30 min, and immediately after, evaluated for antidepressant-like effects. The results were compared with those obtained from mice treated with the serotonergic antidepressant clomipramine (CMI), the noradrenergic antidepressant desipramine (DMI), and the glutamatergic antidepressants, ketamine and MK-801. In the second part, we analyzed the effect of a combined administration of a subeffective concentration of toluene with a suboptimal dose of the various antidepressants acting at different neurotransmitter systems. RESULTS Toluene produced a concentration-dependent antidepressant-like action in the FST and TST and facilitated both MK-801 and ketamine antidepressant-like effects, but not those of DMI or CMI. CONCLUSIONS Toluene has antidepressant-like effects that are synergized with NMDA receptor antagonists.
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Affiliation(s)
- Silvia L Cruz
- Departamento de Farmacobiologia, Cinvestav, Sede Sur, Calzada de Tenorios 235, Col. Granjas Coapa, Mexico City C.P. 14330, Mexico
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Lubman DI, Yücel M, Lawrence AJ. Inhalant abuse among adolescents: neurobiological considerations. Br J Pharmacol 2008; 154:316-26. [PMID: 18332858 PMCID: PMC2442441 DOI: 10.1038/bjp.2008.76] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 01/31/2008] [Accepted: 02/12/2008] [Indexed: 12/15/2022] Open
Abstract
Experimentation with volatile substances (inhalants) is common during early adolescence, yet limited work has been conducted examining the neurobiological impact of regular binge use during this key stage of development. Human studies consistently demonstrate that chronic use is associated with significant toxic effects, including neurological and neuropsychological impairment, as well as diffuse and subtle changes in white matter. However, most preclinical research has tended to focus on acute exposure, with limited work examining the neuropharmacological or toxicological mechanisms underpinning these changes or their potential reversibility with abstinence. Nevertheless, there is growing evidence that commonly abused inhalants share common cellular mechanisms, and have similar actions to other drugs of abuse. Indeed, the majority of acute behavioural effects appear to be underpinned by changes in receptor and/or ion channel activity (for example, GABA(A), glycine and 5HT(3) receptor activation, NMDA receptor inhibition), although nonspecific interactions can also arise at high concentrations. Recent studies examining the effects of toluene exposure during the early postnatal period are suggestive of long-term alterations in the function of NMDA and GABA(A) receptors, although limited work has been conducted investigating exposure during adolescence. Given the critical role of neurotransmitter systems in cognitive, emotional and brain development, future studies will need to take account of the substantial neuromaturational changes that are known to occur in the brain during childhood and adolescence, and to specifically investigate the neuropharmacological and toxicological profile of inhalant exposure during this period of development.
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Affiliation(s)
- D I Lubman
- ORYGEN Research Centre, Department of Psychiatry, The University of Melbourne, Melbourne, Australia.
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Imre G. The preclinical properties of a novel group II metabotropic glutamate receptor agonist LY379268. CNS DRUG REVIEWS 2008; 13:444-64. [PMID: 18078428 DOI: 10.1111/j.1527-3458.2007.00024.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Activation of group II metabotropic glutamate (mGlu2/3) receptors reduces excessive glutamate release that is often associated with neurodegenerative and psychiatric disorders. This finding encouraged the search for potent and selective agonists as potential therapeutic agents. The search led to the discovery of LY379268 {(-)-2-oxa-4-aminobicyclo[3.1.0]hexane-4,6-dicarboxylic acid}, which is a highly potent and systemically available mGlu2/3 receptor agonist. LY379268 was effective in several animal models of stroke, epilepsy, drug abuse, schizophrenia, and pain. Suppression of motor activity is the major side effect of LY379268. Upon repeated administration tolerance develops to this side effect, while the therapeutic effects of LY379268 remain. To date, no clinical data with LY379268 are available. This review article summarizes the preclinical pharmacology of LY379268.
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Affiliation(s)
- Gabor Imre
- Department of Behavioral Pharmacology, Gedeon Richter Ltd., Budapest, Hungary.
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Bowen SE, Charlesworth JD, Tokarz ME, Wright MJ, Wiley JL. Decreased sensitivity in adolescent vs. adult rats to the locomotor activating effects of toluene. Neurotoxicol Teratol 2007; 29:599-606. [PMID: 17869480 PMCID: PMC2156189 DOI: 10.1016/j.ntt.2007.08.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Revised: 08/06/2007] [Accepted: 08/08/2007] [Indexed: 10/22/2022]
Abstract
Volatile organic solvent (inhalant) abuse continues to be a major health concern throughout the world. Of particular concern is the abuse of inhalants by adolescents because of its toxicity and link to illicit drug use. Toluene, which is found in many products such as glues and household cleaners, is among the most commonly abused organic solvents. While studies have assessed outcomes of exposure to inhalants in adult male animals, there is little research on the neurobehavioral effects of inhalants in female or younger animals. In attempt to address these shortcomings, we exposed male and female Long-Evans rats to 20 min of 0, 2000, 4000, or 8000 parts per million (ppm) inhaled toluene for 10 days in rats aged postnatal (PN) day 28-39 (adolescent), PN44-PN55, or >PN70 (adult). Animals were observed individually in 29-l transparent glass cylindrical jars equipped with standard photocells that were used to measure locomotor activity. Toluene significantly increased activity as compared to air exposure in all groups of male and female rats with the magnitude of locomotor stimulation produced by 4000 ppm toluene being significantly greater for female adults than during any age of adolescence. The results demonstrate that exposure to abuse patterns of high concentrations of toluene through inhalation can alter spontaneous locomotor behavior in rats and that the expression of these effects appears to depend upon the postnatal age of testing and sex of the animal.
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Affiliation(s)
- Scott E Bowen
- Department of Psychology, Wayne State University, Detroit, Michigan, USA.
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Riegel AC, Zapata A, Shippenberg TS, French ED. The abused inhalant toluene increases dopamine release in the nucleus accumbens by directly stimulating ventral tegmental area neurons. Neuropsychopharmacology 2007; 32:1558-69. [PMID: 17213847 DOI: 10.1038/sj.npp.1301273] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Recreational abuse of toluene-containing volatile inhalants by adolescents is a significant public health problem. The mechanisms underlying the abuse potential of such substances remain unclear, but could involve increased activity in mesoaccumbal dopamine (DA) afferents innervating the nucleus accumbens (ACB). Here, using in vitro electrophysiology, we show that application of behaviorally relevant concentrations of toluene directly stimulates DA neurons in the ventral tegmental area (VTA), but not surrounding midbrain regions. Toluene stimulation of VTA neurons persists when synaptic transmission is reduced. Moreover, unlike non-DA neurons, the magnitude of VTA DA neuron firing does not decline during longer exposures designed to emulate 'huffing'. Using dual-probe in vivo microdialysis, we show that perfusion of toluene directly into the VTA increases DA concentrations in the VTA (somatodendritic release) and its terminal projection site, the ACB. These results provide the first demonstration that even brief exposure to toluene increases action potential drive onto mesoaccumbal VTA DA neurons, thereby enhancing DA release in the ACB. The finding that toluene stimulates mesoaccumbal neurotransmission by activating VTA DA neurons directly (independently of transynaptic inputs) provide insights into the neural substrates that may contribute to the initiation and pathophysiology of toluene abuse.
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Affiliation(s)
- Arthur C Riegel
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, USA.
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O'Leary-Moore SK, Galloway MP, McMechan AP, Hannigan JH, Bowen SE. Region-dependent alterations in glutamate and GABA measured by high-resolution magnetic resonance spectroscopy following acute binge inhalation of toluene in juvenile rats. Neurotoxicol Teratol 2007; 29:466-75. [PMID: 17466488 DOI: 10.1016/j.ntt.2007.03.062] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 02/14/2007] [Accepted: 03/16/2007] [Indexed: 11/19/2022]
Abstract
Little is known about the neurochemical effects accompanying the high-concentration inhalant exposures characteristic of binge solvent abuse. In adult animals, prior studies with other patterns of exposure indicate that toluene, a commonly abused household and industrial solvent, has significant effects on the glutamatergic and GABAergic neurotransmitter systems and on other neurotransmitter systems as well. In the current investigation, high-resolution "magic angle" spinning proton magnetic resonance spectroscopy (HR-MAS (1)H-MRS) was used to assess the effect of acute binge toluene inhalation on regional brain concentrations of various neurochemicals including glutamate (GLU), GABA, and glutamine (GLN) in juvenile male and female rats. Acute toluene (8000 ppm or 12,000 ppm) significantly reduced levels of hippocampal GABA (-12%) and GLU (-8%), and the GLU/GLN ratio, an index of glutamatergic tone, was significantly reduced (-22%) in the dorsal anterior striatum, driven largely by a 28% increase in GLN. Significant increases in alanine and lactate in several brain regions after acute toluene may be indicative of altered oxygen-dependent metabolism associated with the inhalation of higher concentrations of toluene (e.g., >5000 ppm). Other components of the MR-visible neurochemical profile, such as N-acetylaspartate (NAA), myo-inositol, creatine, and various choline containing compounds, were unchanged by acute toluene. The results are consistent with the notion that binge toluene exposure affects juvenile neurochemistry in systems mediating the rewarding and emotional aspects of substance abuse. Moreover the results provide a framework to understand further (1)H-MRS studies in clinical populations.
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Affiliation(s)
- S K O'Leary-Moore
- Department of Psychology, Wayne State University, Detroit, MI 48201, United States
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43
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Koga Y, Higashi S, Kawahara H, Ohsumi T. Toluene Inhalation Increases Extracellular Noradrenaline and Dopamine in the Medial Prefrontal Cortex and Nucleus Accumbens in Freely-Moving Rats. ACTA ACUST UNITED AC 2007. [DOI: 10.2504/kds.61.39] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Bowen SE, Batis JC, Paez-Martinez N, Cruz SL. The last decade of solvent research in animal models of abuse: mechanistic and behavioral studies. Neurotoxicol Teratol 2006; 28:636-47. [PMID: 17064879 DOI: 10.1016/j.ntt.2006.09.005] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Revised: 09/08/2006] [Accepted: 09/09/2006] [Indexed: 11/20/2022]
Abstract
The abuse of volatile organic solvents (inhalants) leads to diverse sequelae at levels ranging from the cell to the whole organism. This paper reviews findings from the last 10 years of animal models investigating the behavioral and mechanistic effects of solvent abuse. In research with animal models of inhalant abuse, NMDA, GABA(A), glycine, nicotine, and 5HT(3) receptors appear to be important targets of action for several abused solvents with emerging evidence suggesting that other receptor subtypes and nerve membrane ion channels may be involved as well. The behavioral effects vary in magnitude and duration among the solvents investigated. The behavioral effects of acute and chronic inhalant abuse include motor impairment, alterations in spontaneous motor activity, anticonvulsant effects, anxiolytic effects, sensory effects, and effects on learning, memory and operant behavior (e.g., response rates and discriminative stimulus effects). In addition, repeated exposure to these solvents may produce tolerance, dependence and/or sensitization to these effects.
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Affiliation(s)
- Scott E Bowen
- Department of Psychology, Wayne State University, 5057 Woodward, Detroit, MI 48202, USA.
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Schiffer WK, Lee DE, Alexoff DL, Ferrieri R, Brodie JD, Dewey SL. Metabolic correlates of toluene abuse: decline and recovery of function in adolescent animals. Psychopharmacology (Berl) 2006; 186:159-67. [PMID: 16703400 DOI: 10.1007/s00213-006-0359-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Accepted: 02/21/2006] [Indexed: 10/24/2022]
Abstract
RATIONALE Children and adolescents will readily abuse household products that contain solvents such as toluene. It is likely that reinforcing exposures to toluene alter brain glucose metabolism. OBJECTIVE Using an animal model of drug reinforcement, we sought to identify a metabolic signature of toluene abuse in the adolescent rodent brain. Small animal PET (microPET), in combination with the glucose analog radiotracer, (18)FDG, were used to evaluate the metabolic consequences of inhaled toluene. METHODS The exposure protocol paralleled our previously established method for assessing the conditioned reinforcing effects of toluene (5,000 ppm) using the conditioned place preference (CPP) paradigm. Animals were scanned at baseline and 2 h after the last exposure. Follow-up (18)FDG scans occurred 1 day, 3 weeks, and 2 months later. RESULTS After six pairings, 38% of the animals preferred the toluene paired chamber and 25% were averse. The immediate metabolic effect in toluene-exposed animals was a 20% decline in whole brain (18)FDG uptake. Twenty-four hours following the last exposure, the whole brain decline was 40%, and 2 months later, the decline was 30% of pretoluene levels. A region-by-region analysis demonstrated significant additional decreases in the pons, cerebellum, striatum, midbrain, temporal cortex, and hippocampus. Two months after toluene cessation, regions of complete metabolic recovery were the thalamus and cerebellum; however, the temporal cortex did not recover. CONCLUSIONS Brain uptake of (18)FDG appears to be a useful tool for examining the metabolic impact of toluene abuse, which include a profound decline followed by region-specific recovery after cessation.
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Affiliation(s)
- Wynne K Schiffer
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
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Bowen SE, Balster RL. Tolerance and sensitization to inhaled 1,1,1-trichloroethane in mice: results from open-field behavior and a functional observational battery. Psychopharmacology (Berl) 2006; 185:405-15. [PMID: 16541244 DOI: 10.1007/s00213-006-0335-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Accepted: 01/23/2006] [Indexed: 10/24/2022]
Abstract
RATIONALE 1,1,1-Trichloroethane (TCE), a representative abused solvent, has well described acute behavioral effects in animals. Much less is known about repeated high-concentration exposures as would be encountered in inhalant abusers. Tolerance has been demonstrated in some, but not all, studies with TCE while sensitization has also been seen with other abused solvents. OBJECTIVE The present study was designed to further characterize changes in the effects of repeated exposure to TCE on a variety of mouse behaviors. METHODS Mice were tested using locomotor activity as well as a functional observational battery (FOB) both before and after a regimen of daily exposures to various concentrations of TCE. RESULTS The initial locomotor effects of acute 30-min exposures to TCE were biphasic with concentration-dependent increases in activity at lower concentrations and decreases observed at higher concentrations. The profile of acute effects as measured by the FOB included changes in posture, decreased arousal, disturbances in gait, delayed righting reflexes, and decreased sensorimotor reactivity. Animals were then divided into five groups and exposed 30 min/day to either air or one of four concentrations of TCE (2,000, 6,000, 10,000, or 13,300 ppm) for 15 consecutive days. The TCE concentration used primarily affected the magnitude of change, not whether tolerance or sensitization occurred. Tolerance developed on the measures of forelimb grip strength, inverted screen, and number of rears. Conversely, sensitization developed to measures of locomotor activity. CONCLUSION Depending on the behavioral measure, both tolerance and sensitization can occur in mice with repeated exposure to TCE. Both of these phenomena are characteristic of drugs of abuse.
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Affiliation(s)
- Scott E Bowen
- Department of Psychology, Wayne State University, 5057 Woodward Ave., Detroit, MI 48202, USA.
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Lo PS, Chen HH. Immunohistochemical localization of toluene-induced c-Fos protein expression in the rat brain. Toxicol Lett 2005; 157:151-60. [PMID: 15837002 DOI: 10.1016/j.toxlet.2005.01.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2004] [Revised: 01/25/2005] [Accepted: 01/25/2005] [Indexed: 11/15/2022]
Abstract
Although toluene is a widely abused substance, the neuronal populations and pathways mediating its effects are not well understood. Using c-Fos protein as a marker for neuronal activation, the present study investigated the pattern of c-Fos induction at 1h after various doses (0, 300, 750, and 1000 mg/kg, i.p.) of toluene injection in adult male rats. Quantitative analysis of Fos-immunoreactive neurons indicated toluene dose-related induced c-Fos immunoreactivity in the majority of structures examined. The structures included several cortex subareas (primary motor cortex, secondary motor cortex, somatosensory cortex, frontal association cortex, cigulate cortex area 1, cigulate cortex area 2, prelimbic cortex, infralimbic cortex, retrosplenial agranular cortex, ventral orbital cortex, lateral orbital cortex, and piriform cortex), ventral tegmental area, nucleus accumbens shell, thalamic nuclei (mediodorsal, lateral posterior, and laterodorsal ventrolateral) and pontine nuclei. However, the substantia nigra, caudate putamen, nucleus accumbens core, subthalamic nucleus, hippocampus and cerebellum were almost unaffected. The data demonstrate that toluene dose-related induced a unique pattern of c-Fos immunoreactivity. The widespread distribution of toluene-induced c-Fos expression seen in this study can be linked to the profound alterations in physiological function and behavior produced by this solvent.
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Affiliation(s)
- Pi-Shih Lo
- Department of Pharmacy, Buddhist Dalin Tzu Chi General Hospital, Chia Yi, Taiwan, ROC
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Kendell SF, Krystal JH, Sanacora G. GABA and glutamate systems as therapeutic targets in depression and mood disorders. Expert Opin Ther Targets 2005; 9:153-68. [PMID: 15757488 DOI: 10.1517/14728222.9.1.153] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Advances made in diverse areas of neuroscience suggest that neurotransmitter systems, additional to the monoaminergic, contribute to the pathophysiology of mood disorders. This ever accruing body of preclinical and clinical research is providing increased recognition of the contribution made by amino acid neurotransmitters to the neurobiology of mood disorders. This review examines evidence supporting the role of GABA and glutamate in these processes and explores the potential to target these systems in the development of novel compounds; the viability of these agents for treatment-related co-morbidities will also be considered.
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Affiliation(s)
- Steven F Kendell
- Yale University School of Medicine, Department of Psychiatry, 333 Cedar Street, New Haven, CT 06510, USA
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