RESUMO
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the selective loss of motoneurons. While the principal cause of the disease remains so far unknown, the onset and progression of the pathology are increasingly associated with alterations in the control of cell metabolism. On the basis of the well-known key roles of 5'-adenosine monophosphate-activated protein kinase (AMPK) in sensing and regulating the intracellular energy status, we hypothesized that mice with a genetic deletion of AMPK would develop locomotor abnormalities that bear similarity with those detected in the very early disease stage of mice carrying the ALS-associated mutated gene hSOD1(G93A). Using an automated gait analysis system (CatWalk), we here show that hSOD1(G93A) mice and age-matched mice lacking the neuronal and skeletal muscle predominant α2 catalytic subunit of AMPK showed an altered gait, clearly different from wild type control mice. Double mutant mice lacking AMPK α2 and carrying hSOD1(G93A) showed the same early gait abnormalities as hSOD1(G93A) mice over an age span of 8 to 16 weeks. Taken together, these data support the concept that altered AMPK function and associated bioenergetic abnormalities could constitute an important component in the early pathogenesis of ALS. Therapeutic interventions acting on metabolic pathways could prove beneficial on early locomotor deficits, which are sensitively detectable in rodent models using the CatWalk system.
Assuntos
Adenilato Quinase/deficiência , Adenilato Quinase/genética , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/psicologia , Transtornos Neurológicos da Marcha/metabolismo , Transtornos Neurológicos da Marcha/psicologia , Envelhecimento/psicologia , Animais , Progressão da Doença , Metabolismo Energético/genética , Transtornos Neurológicos da Marcha/etiologia , Humanos , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Superóxido Dismutase/genética , Superóxido Dismutase-1RESUMO
In the absence of appropriate medical care, exposure to organophosphorus nerve agents, such as VX, can lead to respiratory failure, and potentially death by asphyxiation. Despite the critical role of respiratory disturbances in organophosphorus-induced toxicity, the nature and underlying mechanisms of respiratory failure remain poorly understood. This study aimed to characterize respiratory alterations by determining their type and duration in mice exposed to a subcutaneous sublethal dose of VX. Respiratory ventilation in Swiss mice was monitored using dual-chamber plethysmography for up to 7 days post-exposure. Cholinesterase activity was assessed via spectrophotometry, and levels of inflammatory biomarkers were quantified using Luminex technology in blood and tissues involved in respiration (diaphragm, lung, and medulla oblongata). Additionally, a histological study was conducted on these tissues to ensure their structural integrity. Ventilatory alterations appeared 20-25â¯minutes after the injection of 0.9 LD50 VX and increased until the end of the recording, i.e., 40â¯minutes after intoxication. Concurrent with the occurrence of apnea, increased inspiratory and expiratory times resulted in a significant decrease in respiratory rate in exposed mice compared to controls. Ventilatory amplitude and, consequently, minute volume were reduced, while specific airway resistance significantly increased, indicating bronchoconstriction. These ventilatory effects persisted up to 24 or even 72â¯hours post-intoxication, resolving on the 7th day. They were correlated with a decrease in acetylcholinesterase activity in the diaphragm, which persisted for up to 72â¯hours, and with the triggering of an inflammatory reaction in the same tissue. No significant histologic lesions were observed in the examined tissues. The ventilatory alterations observed up to 72â¯hours post-VX exposure appear to result from a functional failure of the respiratory system rather than tissue damage. This comprehensive characterization contributes to a better understanding of the respiratory effects induced by VX exposure, which is crucial for developing specific medical countermeasures.
Assuntos
Substâncias para a Guerra Química , Compostos Organotiofosforados , Animais , Substâncias para a Guerra Química/toxicidade , Camundongos , Masculino , Compostos Organotiofosforados/toxicidade , Acetilcolinesterase/metabolismo , Pulmão/efeitos dos fármacos , Pulmão/patologia , Diafragma/efeitos dos fármacosRESUMO
Despite the international convention on the prohibition of chemical weapons ratified in 1997, the threat of conflicts and terrorist attacks involving such weapons still exists. Among these, organophosphorus-nerve agents (OPs) inhibit cholinesterases (ChE) causing cholinergic syndrome. The reactivation of these enzymes is therefore essential to protect the poisoned people. However, these reactivating molecules, mainly named oximes, have major drawbacks with limited efficacy against some OPs and a non-negligible ChE inhibitor potential if administered at an inadequate dose, an effect that they are precisely supposed to mitigate. As a result, this project focused on assessing therapeutic efficacy, in mice, up to the NOAEL dose, the maximum dose of oxime that does not induce any observable toxic effect. NOAEL doses of HI-6 DMS, a reference oxime, and JDS364. HCl, a candidate reactivator, were assessed using dual-chamber plethysmography, with respiratory ventilation impairment as a toxicity criterion. Time-course modeling parameters and pharmacodynamic profiles, reflecting the interaction between the oxime and circulating ChE, were evaluated for treatments at their NOAEL and higher doses. Finally, the therapeutic potential against OPs poisoning was determined through the assessment of protective indices. For JDS364. HCl, the NOAEL dose corresponds to the smallest dose inducing the most significant therapeutic effect without causing any abnormality in ChE activity. In contrast, for HI-6 DMS, its therapeutic benefit was observed at doses higher than its NOAEL, leading to alterations in respiratory function. These alterations could not be directly correlated with ChE inhibition and had no adverse effects on survival. They are potentially attributed to the stimulation of non-enzymatic cholinergic targets by HI-6 DMS. Thus, the NOAEL appears to be an optimal dose for evaluating the efficacy of oximes, particularly when it can be linked to respiratory alterations effectively resulting from ChE inhibition.
Assuntos
Substâncias para a Guerra Química , Reativadores da Colinesterase , Agentes Neurotóxicos , Humanos , Camundongos , Animais , Reativadores da Colinesterase/farmacologia , Reativadores da Colinesterase/uso terapêutico , Reativadores da Colinesterase/química , Agentes Neurotóxicos/toxicidade , Nível de Efeito Adverso não Observado , Substâncias para a Guerra Química/toxicidade , Oximas/farmacologia , Oximas/uso terapêutico , Oximas/química , Compostos de Piridínio/farmacologia , Inibidores da Colinesterase/toxicidade , Inibidores da Colinesterase/química , Colinesterases , Acetilcolinesterase , Antídotos/farmacologia , Antídotos/uso terapêuticoRESUMO
Oriental lacquer has been used in Asian countries for thousands of years as a durable and aesthetic coating material for its adhesive, consolidating, protective and decorative properties. Although these objects are made from an unusual material in Occident, Western museum collections host many lacquerwares. Curators, restorers and scientists are daily confronted with questions of their conservation and their alteration. The characterization of their conservation state is usually assessed through visual observations. However deterioration often starts at the microscopic level and cannot be detected by a simple visual inspection. Often, ageing and deterioration of artworks are connected to physical, mechanical and chemical transformations. Thus new insight into alteration of lacquer involves the monitoring of macro-, microscopic and molecular modifications, and this can be assessed from physico-chemical measurements. Non-invasive (microtopography and Scanning Electron Microscopy - SEM) and micro-invasive (infrared micro-spectroscopy using a synchrotron source - SR-µFTIR) investigations were performed to study the degradation processes of lacquers and evaluate their level of alteration. In particular, spectral decomposition and fitting procedure were performed in the 1820-1520 cm(-1) region to follow the shift of the C=O and C=C band positions during lacquer ageing. The present work proves the potential of this physico-chemical approach in conservation studies of lacquers and in the quantification of the state of alteration. It evidences chemical phenomena of alteration such as oxidation and decomposition of a lacquer polymeric network. It also demonstrates for the first time the degradation front of artificially aged lacquer and the chemical imaging of a more than 2000 years old archaeological lacquer by using SR-µFTIR.
Assuntos
Fenômenos Químicos , Laca/análise , Imagem Multimodal/métodos , Árvores , Ásia , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Árvores/químicaRESUMO
Recent events demonstrated that organophosphorus nerve agents are a serious threat for civilian and military populations. The current therapy includes a pyridinium aldoxime reactivator to restore the enzymatic activity of acetylcholinesterase located in the central nervous system and neuro-muscular junctions. One major drawback of these charged acetylcholinesterase reactivators is their poor ability to cross the blood-brain barrier. In this study, we propose to evaluate glucoconjugated oximes devoid of permanent charge as potential central nervous system reactivators. We determined their in vitro reactivation efficacy on inhibited human acetylcholinesterase, the crystal structure of two compounds in complex with the enzyme, their protective index on intoxicated mice, and their pharmacokinetics. We then evaluated their endothelial permeability coefficients with a human in vitro model. This study shed light on the structural restrains of new sugar oximes designed to reach the central nervous system through the glucose transporter located at the blood-brain barrier.
Assuntos
Intoxicação por Organofosfatos , Acetilcolinesterase , Animais , Antídotos/farmacologia , Antídotos/uso terapêutico , Inibidores da Colinesterase/farmacologia , Camundongos , Intoxicação por Organofosfatos/tratamento farmacológico , Compostos Organofosforados/farmacologia , Oximas/química , Oximas/farmacologia , Oximas/uso terapêutico , AçúcaresRESUMO
Organophosphorus (OP) cholinesterase inhibitors, which include insecticides and chemical warfare nerve agents, are very potent neurotoxicants. Given that the actual treatment has several limitations, the present study provides a general method, called the zebrafish-OP-antidote test (ZOAT), and basic scientific data, to identify new antidotes that are more effective than the reference pyridinium oximes after acute OP poisoning. The reactivation capacity of a chemical compound can be measured using in vivo and ex vivo acetylcholinesterase (AChE) assays. We demonstrated that it is possible to differentiate between chemical compound protective efficacies in the central and peripheral nervous system via the visual motor response and electric field pulse motor response tests, respectively. Moreover, the ability to cross the brain-blood barrier can be estimated in a physiological context by combining an AChE assay on the head and trunk-tail fractions and the cellular and tissue localization of AChE activity in the whole-mount animal. ZOAT is an innovative method suitable for the screening and rapid identification of chemicals and mixtures used as antidote for OP poisoning. The method will make it easier to identify more effective medical countermeasures for chemical threat agents, including combinatorial therapies.
Assuntos
Reativadores da Colinesterase , Intoxicação por Organofosfatos , Acetilcolinesterase , Animais , Antídotos/farmacologia , Inibidores da Colinesterase/farmacologia , Reativadores da Colinesterase/farmacologia , Larva , Intoxicação por Organofosfatos/tratamento farmacológico , Oximas , Peixe-ZebraRESUMO
(1) Background: Human exposure to organophosphorus compounds employed as pesticides or as chemical warfare agents induces deleterious effects due to cholinesterase inhibition. One therapeutic approach is the reactivation of inhibited acetylcholinesterase by oximes. While currently available oximes are unable to reach the central nervous system to reactivate cholinesterases or to display a wide spectrum of action against the variety of organophosphorus compounds, we aim to identify new reactivators without such drawbacks. (2) Methods: This study gathers an exhaustive work to assess in vitro and in vivo efficacy, and toxicity of a hybrid tetrahydroacridine pyridinaldoxime reactivator, KM297, compared to pralidoxime. (3) Results: Blood-brain barrier crossing assay carried out on a human in vitro model established that KM297 has an endothelial permeability coefficient twice that of pralidoxime. It also presents higher cytotoxicity, particularly on bone marrow-derived cells. Its strong cholinesterase inhibition potency seems to be correlated to its low protective efficacy in mice exposed to paraoxon. Ventilatory monitoring of KM297-treated mice by double-chamber plethysmography shows toxic effects at the selected therapeutic dose. This breathing assessment could help define the No Observed Adverse Effect Level (NOAEL) dose of new oximes which would have a maximum therapeutic effect without any toxic side effects.
Assuntos
Acetilcolinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Compostos de Pralidoxima/farmacologia , Animais , Barreira Hematoencefálica/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Inibidores da Colinesterase/administração & dosagem , Inibidores da Colinesterase/química , Relação Dose-Resposta a Droga , Humanos , Injeções Intraperitoneais , Masculino , Camundongos , Estrutura Molecular , Compostos de Pralidoxima/química , Proteínas Recombinantes/metabolismoRESUMO
Respiration failure during exposure by cholinesterase inhibitors has been widely assumed to be due to inhibition of cholinesterase in the brain. Using a double chamber plethysmograph to measure various respiratory parameters, we observed long "end inspiratory pauses" (EIP) during most exposure that depressed breathing. Surprisingly, Colq KO mice that have a normal level of acetylcholinesterase (AChE) in the brain but a severe deficit in muscles and other peripheral tissues do not pause the breathing by long EIP. In mice, long EIP can be triggered by a nasal irritant. Eucalyptol, an agonist of cold receptor (TRPM8) acting on afferent sensory neurons and known to reduce the EIP triggered by such irritants, strongly reduced the EIP induced by cholinesterase inhibitor. These results suggest that acetylcholine (ACh) spillover from the neuromuscular junction, which is unchanged in Colq KO mice, may activate afferent sensory systems and trigger sensory reflexes, as reversed by eucalyptol. Indeed, the role of AChE at the cholinergic synapses is not only to accurately control the synaptic transmission but also to prevent the spillover of ACh. In the peripheral tissues, the ACh flood induced by cholinesterase inhibition may be very toxic due to interaction with non-neuronal cells that use ACh at low levels to communicate with afferent sensory neurons.
Assuntos
Acetilcolina/metabolismo , Inibidores da Colinesterase/toxicidade , Reflexo/efeitos dos fármacos , Insuficiência Respiratória/induzido quimicamente , Células Receptoras Sensoriais , Transdução de Sinais/fisiologia , Acetilcolinesterase/metabolismo , Animais , Colágeno/metabolismo , Feminino , Irritantes/toxicidade , Masculino , Camundongos , Camundongos Knockout , Proteínas Musculares/metabolismo , Junção Neuromuscular/efeitos dos fármacos , Fisostigmina/toxicidade , Brometo de Piridostigmina/toxicidade , Respiração/efeitos dos fármacos , Insuficiência Respiratória/fisiopatologiaRESUMO
Glufosinate-ammonium (GLA), the active compound of a worldwide-used herbicide, acts by inhibiting the plant glutamine synthetase (GS) leading to a lethal accumulation of ammonia. GS plays a pivotal role in the mammalian brain where it allows neurotransmitter glutamate recycling within astroglia. Clinical studies report that an acute GLA ingestion induces convulsions and memory impairment in humans. Toxicological studies performed at doses used for herbicidal activity showed that GLA is probably harmless at short or medium range periods. However, effects of low doses of GLA on chronically exposed subjects are not known. In our study, C57BL/6J mice were treated during 10 weeks three times a week with 2.5, 5 and 10mg/kg of GLA. Effects of this chronic treatment were assessed at behavioral, structural and metabolic levels by using tests of spatial memory, locomotor activity and anxiety, hippocampal magnetic resonance imaging (MRI) texture analysis, and hippocampal GS activity assay, respectively. Chronic GLA treatments have effects neither on anxiety nor on locomotor activity of mice but at 5 and 10mg/kg induce (1) mild memory impairments, (2) a modification of hippocampal texture and (3) a significant increase in hippocampal GS activity. It is suggested that these modifications may be causally linked one to another. Since glutamate is the main neurotransmitter in hippocampus where it plays a crucial role in spatial memory, hippocampal MRI texture and spatial memory alterations might be the consequences of hippocampal glutamate homeostasis modification revealed by increased GS activity in hippocampus. The present study provides the first data that show cerebral alterations after chronic exposure to GLA.
Assuntos
Aminobutiratos/toxicidade , Glutamato-Amônia Ligase/metabolismo , Hipocampo/efeitos dos fármacos , Transtornos da Memória/induzido quimicamente , Percepção Espacial/efeitos dos fármacos , Análise de Variância , Animais , Comportamento Animal/efeitos dos fármacos , Distribuição de Qui-Quadrado , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Comportamento Exploratório/efeitos dos fármacos , Hipocampo/patologia , Imageamento por Ressonância Magnética/métodos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Transtornos da Memória/enzimologia , Transtornos da Memória/patologia , Camundongos , Camundongos Endogâmicos C57BL , Fatores de TempoRESUMO
Organophosphorus nerve agents, like VX, are highly toxic due to their strong inhibition potency against acetylcholinesterase (AChE). AChE inhibited by VX can be reactivated using powerful nucleophilic molecules, most commonly oximes, which are one major component of the emergency treatment in case of nerve agent intoxication. We present here a comparative in vivo study on Swiss mice of four reactivators: HI-6, pralidoxime and two uncharged derivatives of 3-hydroxy-2-pyridinaldoxime that should more easily cross the blood-brain barrier and display a significant central nervous system activity. The reactivability kinetic profile of the oximes is established following intraperitoneal injection in healthy mice, using an original and fast enzymatic method based on the reactivation potential of oxime-containing plasma samples. HI-6 displays the highest reactivation potential whatever the conditions, followed by pralidoxime and the two non quaternary reactivators at the dose of 50 mg/kg bw. But these three last reactivators display equivalent reactivation potential at the same dose of 100 µmol/kg bw. Maximal reactivation potential closely correlates to surviving test results of VX intoxicated mice.
Assuntos
Análise Química do Sangue/métodos , Barreira Hematoencefálica/efeitos dos fármacos , Substâncias para a Guerra Química/toxicidade , Reativadores da Colinesterase/sangue , Compostos Organotiofosforados/toxicidade , Oximas/farmacologia , Compostos de Pralidoxima/farmacologia , Compostos de Piridínio/farmacologia , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Animais , Barreira Hematoencefálica/metabolismo , Eritrócitos/citologia , Eritrócitos/enzimologia , Meia-Vida , Humanos , Injeções Intraperitoneais , Masculino , Camundongos , Oximas/metabolismo , Compostos de Pralidoxima/metabolismo , Substâncias Protetoras/metabolismo , Substâncias Protetoras/farmacologia , Compostos de Piridínio/metabolismoRESUMO
Glufosinate-ammonium (GLA), the active component of a widely used herbicide, induces convulsions in rodents and humans. In mouse, intraperitoneal treatment with 75 mg/kg GLA generates repetitive tonic-clonic seizures associated with 100% mortality within 72 h after treatment. In this context, we characterized GLA-induced seizures, their histological consequences and the effectiveness of diazepam treatment. Epileptic discharges on electroencephalographic recordings appeared simultaneously in the hippocampus and the cerebral cortex. Diazepam treatment at 6 h immediately stopped the seizures and prevented animal death. However, intermittent seizures were recorded on electroencephalogram from 6 h after diazepam treatment until 24 h, but had disappeared after 15 days. In our model, neuronal activation (c-Fos immunohistochemistry) was observed 6 h after GLA exposure in the dentate gyrus, CA1, CA3, amygdala, piriform and entorhinal cortices, indicating the activation of the limbic system. In these structures, Fluoro-Jade C and Cresyl violet staining did not show neuronal suffering. However, astroglial activation was clearly observed at 24 h and 15 days after GLA treatment in the amygdala, piriform and entorhinal cortices by PCR quantitative, western blot and immunohistochemistry. Concomitantly, glutamine synthetase mRNA expression (PCR quantitative), protein expression (western blot) and enzymatic activity were upregulated. In conclusion, our study suggests that GLA-induced seizures: (a) involved limbic structures and (b) induced astrocytosis without neuronal degeneration as an evidence of a reactive astrocyte beneficial effect for neuronal protection.
Assuntos
Aminobutiratos/toxicidade , Encéfalo/efeitos dos fármacos , Herbicidas/toxicidade , Organofosfatos/toxicidade , Convulsões/induzido quimicamente , Animais , Anticonvulsivantes/administração & dosagem , Astrócitos/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/fisiopatologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Córtex Cerebral/fisiopatologia , Diazepam/administração & dosagem , Eletroencefalografia , Glutamato-Amônia Ligase/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/fisiopatologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-fos/metabolismo , Convulsões/metabolismo , Convulsões/fisiopatologiaRESUMO
The therapeutic benefits associated with mesenchymal stem cells (MSCs) largely result from their immunomodulatory and neurotrophic properties. In this study, we evaluated the effects of MSCs on astrocyte cultures exposed to lipopolysaccharide. In response to this inflammatory trigger, astrocytes showed an increased expression of pro-inflammatory genes (IL-1ß, TNFα, IL-6), which was attenuated by pre-exposure to MSC conditioned medium. Furthermore, mediators released by MSCs increased cell proliferation and altered the regulation of intermediate filaments (GFAP, vimentin), pro-inflammatory enzymes (iNOS, COX-2) and receptors (TLR4, CD14, mGluR3, mGluR5). These data demonstrate that MSCs influence diverse cell types participating in the response to neuroinflammation.
Assuntos
Astrócitos/imunologia , Astrócitos/metabolismo , Fatores Imunológicos/metabolismo , Imunomodulação/imunologia , Transplante de Células-Tronco Mesenquimais , Animais , Astrócitos/efeitos dos fármacos , Células Cultivadas , Meios de Cultivo Condicionados/metabolismo , Meios de Cultivo Condicionados/farmacologia , Imuno-Histoquímica , Fatores Imunológicos/farmacologia , Imunomodulação/efeitos dos fármacos , Inflamação/induzido quimicamente , Lipopolissacarídeos/imunologia , Lipopolissacarídeos/toxicidade , Masculino , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
The partial agonist profile of novel antipsychotics such as aripiprazole has hardly been demonstrated in biochemical assays on animal tissues. As it is established that responses induced by dopamine D2 receptor agonists are increased in models of dopaminergic sensitization, this paradigm was used in order to facilitate the detection of the partial agonist properties of aripiprazole. At variance with all other partial and full agonists tested, the partial agonist properties of aripiprazole were not revealed in guanosine 5'-O-(γ-[³5S]thiotriphosphate ([³5S]GTPγS) binding assays on striatal membranes from haloperidol-treated rats. Hence,aripiprazole behaved as an antagonist, efficiently inhibiting the functional response to dopamine. Similarly, in behavioural assays, aripiprazole dose-dependently inhibited the stereotypies elicited by apomorphine. However, at variance with haloperidol, repeated administrations of aripiprazole(3 weeks) at the doses of 10 and 30 mg/kg did not induce any up-regulation or hyperfunctionality of the dopamine D2 receptors in the striatum. These data highlight the putative involvement of other pharmacological targets for aripiprazole that would support in the prevention of secondary effects commonly associated with the blockade of striatal dopamine D2 receptors. Hence, in additional experiments, aripiprazole was found to efficiently promote [³5S]GTPγS binding in hippocampal membranes through the activation of 5-HT(1A) receptors. Further experiments investigating the second messenger cascades should be performed so as to establish the functional properties of aripiprazole and understand the mechanism underlying the prevention of dopamine receptor regulation in spite of the observed antagonism.
Assuntos
Corpo Estriado/metabolismo , Antagonistas dos Receptores de Dopamina D2 , Piperazinas/farmacologia , Quinolonas/farmacologia , Receptores de Dopamina D2/metabolismo , Regulação para Cima/efeitos dos fármacos , Animais , Apomorfina/análogos & derivados , Apomorfina/antagonistas & inibidores , Apomorfina/farmacologia , Aripiprazol , Soluções Tampão , Catalepsia/induzido quimicamente , Catalepsia/diagnóstico , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Corpo Estriado/efeitos dos fármacos , Domperidona/farmacologia , Dopamina/farmacologia , Agonistas de Dopamina/farmacologia , Antagonistas de Dopamina/farmacologia , Antagonismo de Drogas , Agonismo Parcial de Drogas , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Haloperidol/farmacologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Masculino , Piperidinas/farmacologia , Piridinas/farmacologia , Ratos , Ratos Wistar , Receptores de Dopamina D2/agonistas , Receptores 5-HT1 de Serotonina/metabolismo , Serotonina/farmacologia , Antagonistas do Receptor 5-HT1 de Serotonina/farmacologia , Comportamento Estereotipado/efeitos dos fármacosRESUMO
Glufosinate ammonium (GLA) is the active component of herbicides widely used in agriculture, truck farming, or public domains. GLA acts by inhibiting the plant glutamine synthetase (GlnS). It also inhibits mammalian GlnS in vitro and ex vivo. In the central nervous system this enzyme is exclusively localized in glial cells. Whereas acute neurotoxic effects of GLA are well documented, long-term effects during chronic exposure at low doses remain largely undisclosed. In the present work, C57BL/6J mice were treated intraperitoneally with 2.5, 5, and 10 mg/kg of GLA three times a week during 10 weeks. Cerebral magnetic resonance imaging (MRI) experiments were performed at high field (9.4 T) and the images were analyzed with four texture analysis (TA) methods. TA highlighted structural changes in seven brain structures after chronic GLA treatments. Changes are dose dependent and can be seen at a dose as low as 2.5 mg/kg for two areas, namely hippocampus and somatosensorial cortex. Glial fibrillary acidic protein (GFAP) expression in the same seven brain structures and GlnS activity in the hippocampus and cortex areas were also studied. The number of GFAP-positive cells is modified in six out of the seven areas examined. GlnS activity was significantly increased in the hippocampus but not in the cortex. These results indicate some kind of suffering at the cerebral level after chronic GLA treatment. Changes in TA were compared with the modification of the number of GFAP-positive astrocytes in the studied brain areas after GLA treatment. We show that the noninvasive MRI-TA is a sensitive method and we suggest that it would be a very helpful tool that can efficiently contribute to the detection of cerebral alterations in vivo during chronic exposure to xenobiotics.