RESUMO
A review of studies on the body fluid levels of neuroactive amino acids, including glutamate, glutamine, taurine, gamma-aminobutyric acid (GABA), glycine, tryptophan, D-serine, and others, in autism spectrum disorders (ASD) is given. The results reported in the literature are generally inconclusive and contradictory, but there has been considerable variation among the previous studies in terms of factors such as age, gender, number of subjects, intelligence quotient, and psychoactive medication being taken. Future studies should include simultaneous analyses of a large number of amino acids [including D-serine and branched-chain amino acids (BCAAs)] and standardization of the factors mentioned above. It may also be appropriate to use saliva sampling to detect amino acids in ASD patients in the future-this is noninvasive testing that can be done easily more frequently than other sampling, thus providing more dynamic monitoring.
Assuntos
Aminoácidos/metabolismo , Transtorno do Espectro Autista/metabolismo , Líquidos Corporais/química , Transtorno do Espectro Autista/fisiopatologia , Ácido Glutâmico/metabolismo , Glutamina/metabolismo , Glicina/metabolismo , Humanos , Serina/metabolismo , Taurina/metabolismo , Triptofano/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
Multiple sclerosis (MS) and the animal model, experimental autoimmune encephalomyelitis (EAE), are both accompanied by motor and non-motor symptoms. Pathological changes in the activities of key neurotransmitters likely underlie many of these symptoms. We have previously described disturbances in the levels of 5-hydroxytryptamine (5-HT/serotonin), noradrenaline (NE) and γ-aminobutyric acid (GABA) in a mouse model of EAE. The potential therapeutic effect of a drug that targets these three neurotransmitters, the antidepressant and anti-panic drug phenelzine (PLZ), was assessed in mice with MOG(35-55) induced EAE. The neurotransmitter content of EAE and control tissue after PLZ administration was first evaluated by HPLC. The ability of PLZ treatment to modulate EAE disease course and clinical signs was then assessed. Daily PLZ treatment, starting seven days after disease induction, delayed EAE onset, reduced disease severity in the chronic phase and was associated with substantial improvements in exploratory behavior and a novel measure of sickness and/or depression. Upon completion of the experiment, PLZ's effects on histopathological markers of the disease were examined. No differences were observed in T cell infiltration, microglia/macrophage reactivity, demyelination or axonal injury in PLZ-treated spinal cords. However, EAE mice treated with PLZ showed a normalization of 5-HT levels in the ventral horn of the spinal cord that might account for the improvements in behavioral outcomes. These results demonstrate the therapeutic potential of MAO inhibitors such as PLZ in MS. Additionally, the behavioral changes observed in EAE mice indicate that alterations in non-motor or 'affective' measures may be valuable to consider in addition to traditional measures of gross locomotor function.
Assuntos
Encefalomielite Autoimune Experimental/tratamento farmacológico , Inibidores da Monoaminoxidase/uso terapêutico , Fenelzina/uso terapêutico , Afeto/efeitos dos fármacos , Animais , Células do Corno Anterior/efeitos dos fármacos , Química Encefálica/fisiologia , Cromatografia Líquida de Alta Pressão , Progressão da Doença , Encefalomielite Autoimune Experimental/metabolismo , Encefalomielite Autoimune Experimental/patologia , Feminino , Gliose/patologia , Processamento de Imagem Assistida por Computador , Imuno-Histoquímica , Inflamação/patologia , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora/fisiologia , Norepinefrina/metabolismo , Equilíbrio Postural/fisiologia , Recuperação de Função Fisiológica , Serotonina/metabolismo , Medula Espinal/patologia , Resultado do Tratamento , Ácido gama-Aminobutírico/metabolismoRESUMO
L-Serine-O-phosphate (L-SOP), the precursor of l-serine, is an agonist at group III metabotropic glutamate receptors. Despite the interest in L-SOP, very few articles have reported its brain levels. Here we report a convenient and reproducible method for simultaneous analysis of L-SOP and several other important amino acids in brain tissue using high-performance liquid chromatography (HPLC) with fluorimetric detection after derivatization with o-phthaldialdehyde and N-isobutyl-L-cysteine. Analyses were carried out in rat whole brain and cerebellum and in mouse whole brain, forebrain, amygdala, and prefrontal cortex. The method should be useful for future comprehensive neurochemical and pharmacological studies on neuropsychiatric disorders.
Assuntos
Química Encefálica , Cromatografia Líquida de Alta Pressão/métodos , Fluorometria/métodos , Fosfosserina/análise , Animais , Encéfalo/metabolismo , Cerebelo , Camundongos , Camundongos Endogâmicos C57BL , Córtex Pré-Frontal/química , Ratos , Ratos Sprague-Dawley , Serina/metabolismoRESUMO
BACKGROUND: Gabapentin is a structural analog of the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Its anticonvulsant, analgesic and anxiolytic properties suggest that it increases GABAergic inhibition; however, the molecular basis for these effects is unknown as gabapentin does not directly modify GABA type A (GABAA) receptor function, nor does it modify synaptic inhibition. Here, we postulated that gabapentin increases expression of δ subunit-containing GABAA (δGABAA) receptors that generate a tonic inhibitory conductance in multiple brain regions including the cerebellum and hippocampus. METHODS: Cell-surface biotinylation, Western blotting, electrophysiologic recordings, behavioral assays, high-performance liquid chromatography and gas chromatography-mass spectrometry studies were performed using mouse models. FINDINGS: Gabapentin enhanced expression of δGABAA receptors and increased a tonic inhibitory conductance in neurons. This increased expression likely contributes to GABAergic effects as gabapentin caused ataxia and anxiolysis in wild-type mice but not δ subunit null-mutant mice. In contrast, the antinociceptive properties of gabapentin were observed in both genotypes. Levels of GABAA receptor agonists and neurosteroids in the brain were not altered by gabapentin. INTERPRETATION: These results provide compelling evidence to account for the GABAergic properties of gabapentin. Since reduced expression of δGABAA receptor occurs in several disorders, gabapentin may have much broader therapeutic applications than is currently recognized. FUND: Supported by a Foundation Grant (FDN-154312) from the Canadian Institutes of Health Research (to B.A.O.); a NSERC Discovery Grant (RGPIN-2016-05538), a Canada Research Chair in Sensory Plasticity and Reconsolidation, and funding from the University of Toronto Centre for the Study of Pain (to R.P.B.).
Assuntos
Antagonistas de Aminoácidos Excitatórios/farmacologia , Gabapentina/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Receptores de GABA-A/genética , Animais , Comportamento Animal , Cerebelo/efeitos dos fármacos , Cerebelo/metabolismo , Cromatografia Líquida de Alta Pressão , Cromatografia Gasosa-Espectrometria de Massas , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Aprendizagem em Labirinto , Camundongos , Camundongos Knockout , Neurônios/metabolismo , Receptores de GABA-A/química , Receptores de GABA-A/metabolismoRESUMO
A group of beta-phenylethylidenehydrazines possessing a variety of substituents (Me, OMe, Cl, F, and CF(3)) at the ortho-, meta-, or para-positions of the phenyl ring, in conjunction with either a N-bis-(2-propynyl) or a N-mono-(2-propynyl) moiety, were synthesized and compared to the novel neuroprotective drug beta-phenylethylidenehydrazine (PEH) with regard to their ability to inhibit the enzymes GABA-transaminase (GABA-T) and monoamine oxidase (MAO)-A and -B in vitro in brain tissue. Two of the analogs synthesized (mono- and bis-N-propynylPEH) were also studied exvivo in rats to compare their effects to those of PEH with regard to ability to inhibit GABA-T and MAO and to change brain levels of several important amino acids. Unlike PEH, none of the new drugs inhibited GABA-T in vitro at 10 or 100 microM, and all of the drugs (including PEH) were poor inhibitors (at 10 microM) of MAO-A and -B invitro. The two analogs studied exvivo inhibited GABA-T to a lesser extent than PEH, unlike PEH that did not elevate brain levels of GABA, and inhibited MAO-A and -B more potently than PEH. Interestingly, unlike PEH, the two analogs caused marked increases in brain levels of glycine; because of the current interest in drugs that increase glycine availability in the brain as potential antipsychotic drugs, these two analogs now warrant further investigation.
Assuntos
4-Aminobutirato Transaminase/antagonistas & inibidores , Alcinos/química , Encéfalo/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Hidrazinas/farmacologia , Monoaminoxidase/efeitos dos fármacos , Animais , Encéfalo/metabolismo , Avaliação Pré-Clínica de Medicamentos , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Glicina/metabolismo , Hidrazinas/síntese química , Hidrazinas/química , Masculino , Estrutura Molecular , Ratos , Ratos Sprague-Dawley , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
The serotonin (5-hydroxytryptamine, 5-HT) transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR) is thought to alter 5-HT signaling and contribute to behavioral and cognitive phenotypes in depression as well as Alzheimer disease (AD). We explored how well the short (S) and long (L) alleles of the 5-HTTLPR align with serotoninergic indices in 60 autopsied cortical samples from early-onset AD/EOAD and late-onset AD/LOAD donors, and age- and sex-matched controls. Stratifying data by either diagnosis-by-genotype or by sex-by-genotype revealed that the donor's 5-HTTLPR genotype, i.e., L/L, S/L, or S/S, did not affect 5-HTT mRNA or protein expression. However, the glycosylation of 5-HTT was significantly higher in control female (vs. male) samples and tended to decrease in female EOAD/LOAD samples, but remained unaltered in male LOAD samples. Glycosylated forms of the vesicular monoamine transporter (VMAT2) were lower in both male and female AD samples, while a sex-by-genotype stratification revealed a loss of VMAT2 glycosylation specifically in females with an L/L genotype. VMAT2 and 5-HTT glycosylation were correlated in male samples and inversely correlated in female samples in both stratification models. The S/S genotype aligned with lower levels of 5-HT turnover in females (but not males) and with an increased glycosylation of the post-synaptic 5-HT2C receptor. Interestingly, the changes in presynaptic glycosylation were evident primarily in female carriers of the APOE ε4 risk factor for AD. Our data do not support an association between 5-HTTLPR genotype and 5-HTT expression, but they do reveal a non-canonical association of 5-HTTLPR genotype with sex-dependent glycosylation changes in pre- and post-synaptic markers of serotoninergic neurons. These patterns of change suggest adaptive responses in 5-HT signaling and could certainly be contributing to the female prevalence in risk for either depression or AD.
RESUMO
Environmental enrichment items such as running wheels can promote the wellbeing of laboratory mice. Growing evidence suggests that wheel running simulates exercise effects in many mouse models of human conditions, but this activity also might change other aspects of mouse behavior. In this case study, we show that the presence of running wheels leads to pronounced and permanent circling behavior with route-tracing in a proportion of the male mice of a genetically distinct cohort. The genetic background of this cohort includes a mutation in Arhgap19, but genetic crosses showed that an unknown second-site mutation likely caused the induced circling behavior. Behavioral tests for inner-ear function indicated a normal sense of gravity in the circling mice. However, the levels of dopamine, serotonin, and some dopamine metabolites were lower in the brains of circling male mice than in mice of the same genetic background that were weaned without wheels. Circling was seen in both singly and socially housed male mice. The additional stress of fighting may have exacerbated the predisposition to circling in the socially housed animals. Singly and socially housed male mice without wheels did not circle. Our current findings highlight the importance and possibly confounding nature of the environmental and genetic background in mouse behavioral studies, given that the circling behavior and alterations in dopamine and serotonin levels in this mouse cohort occurred only when the male mice were housed with running wheels.
Assuntos
Comportamento Animal , Atividade Motora/fisiologia , Corrida , Animais , Encéfalo/metabolismo , Cruzamentos Genéticos , Meio Ambiente , Genótipo , Abrigo para Animais , Masculino , Camundongos , MutaçãoRESUMO
The treatment of progressive multiple sclerosis (MS) is unsatisfactory. One reason is that the drivers of disease, which include iron-mediated neurotoxicity, lymphocyte activity, and oxidative stress, are not simultaneously targeted. Here we present a systematic screen to identify generic, orally available medications that target features of progressive MS. Of 249 medications that cross the blood-brain barrier, 35 prevent iron-mediated neurotoxicity in culture. Of these, several antipsychotics and antidepressants strongly reduce T-cell proliferation and oxidative stress. We focus on the antidepressant clomipramine and found that it additionally inhibits B-lymphocyte activity. In mice with experimental autoimmune encephalomyelitis, a model of MS, clomipramine ameliorates clinical signs of acute and chronic phases. Histologically, clomipramine reduces inflammation and microglial activation, and preserves axonal integrity. In summary, we present a systematic approach to identify generic medications for progressive multiple sclerosis with the potential to advance rapidly into clinical trials, and we highlight clomipramine for further development.
Assuntos
Clomipramina/uso terapêutico , Medicamentos Genéricos/uso terapêutico , Encefalomielite Autoimune Experimental/tratamento farmacológico , Esclerose Múltipla/tratamento farmacológico , Animais , Axônios/efeitos dos fármacos , Axônios/fisiologia , Linfócitos B/efeitos dos fármacos , Linfócitos B/imunologia , Barreira Hematoencefálica/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Clomipramina/farmacologia , Avaliação Pré-Clínica de Medicamentos , Medicamentos Genéricos/farmacologia , Feminino , Voluntários Saudáveis , Humanos , Ferro/toxicidade , Ativação Linfocitária/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Microglia/efeitos dos fármacos , Microglia/imunologia , Terapia de Alvo Molecular/métodos , Estresse Oxidativo/efeitos dos fármacos , Linfócitos T/efeitos dos fármacos , Linfócitos T/fisiologiaRESUMO
Neonatal hypoxia-ischemia (HI) is a major contributor to many neurological, psychiatric and behavioral disorders. Previous studies in our laboratory have shown that a one-time dose of doxycycline (DOXY), even when given 3h after HI insult, was neuroprotective and significantly reduced microglial activation and cleaved caspase-3 protein expression in the immature brain. In light of these data, the goal of this study was to investigate the effects of DOXY administration on amino acid neurotransmitters. Post-natal-day 7 rats received DOXY (10mg/kg) or vehicle (VEH) concomitant with the onset of HI, and were euthanized 30 min, 1, 2 or 4h post-HI (n>or=6). Extracted brains were either immediately dissected for frontal cortex, striatum and hippocampal regions, or removed in their entirety and flash frozen in isopentane for histological analyses. Dissected regions were homogenized and aliquots were prepared for high performance liquid chromatography (HPLC) analyses of amino acid levels and brain levels of DOXY. HPLC extraction revealed that systemic administration of DOXY resulted in mean drug levels of 867.1+/-376.1 ng/g of brain tissue. Histological analyses revealed microglial activation, caspase-3 activation and neuronal degeneration consistent with a mild injury in the regions most vulnerable to HI. We found that HI caused significant, time-dependent, regional changes in brain amino acids including glutamate, GABA, alanine, aspartate, asparagine, serine, glutamine, glycine and taurine. HI significantly increased glutamate levels in the hippocampus (HI+VEH=15.8+/-3.1 ng/microg versus control=11.8+/-1.4 ng/microg protein) 4h post-HI (p<0.05). Pups treated with DOXY had lower glutamate levels (13.1+/-2.4 ng/microg) when compared to VEH-treated pups (15.8+/-3.1 ng/microg), however these values failed to reach significance. In addition, DOXY-treated pups had significantly lower alanine (HI+VEH=1.1+/-0.2 ng/microg versus HI+DOXY=0.5+0.1 ng/microg) and serine (HI+VEH=1.4+/-0.4 ng/microg versus HI+DOXY=0.7+0.1 ng/microg) levels in the hippocampus, 4h post-HI. Similar normalizations and significant reductions in alanine and serine were seen in the cortex and striatum. These results show that in addition to its previously reported and well-documented anti-inflammatory and anti-apoptotic properties, DOXY has significant effects on amino acid neurotransmitters.
Assuntos
Aminoácidos/metabolismo , Doxiciclina/administração & dosagem , Hipóxia-Isquemia Encefálica/metabolismo , Neurotransmissores/metabolismo , Animais , Animais Recém-Nascidos , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Cromatografia Líquida de Alta Pressão , Modelos Animais de Doenças , Imuno-Histoquímica , Ratos , Ratos Sprague-DawleyRESUMO
We have characterized the changes in tissue concentrations of amino acids and biogenic amines in the central nervous system (CNS) of mice with MOG(35-55)-induced experimental autoimmune encephalomyelitis (EAE), an animal model commonly used to study multiple sclerosis (MS). High performance liquid chromatography was used to analyse tissue samples from five regions of the CNS at the onset, peak and chronic phase of MOG(35-55) EAE. Our analysis includes the evaluation of several newly examined amino acids including d-serine, and the inter-relations between the intraspinal concentration changes of different amino acids and biogenic amines during EAE. Our results confirm many of the findings from similar studies using different variants of the EAE model as well as those examining changes in amino acid and biogenic amine levels in the cerebrospinal fluid (CSF) of MS patients. However, several notable differences were observed between mice with MOG(35-55)-induced EAE with findings from human studies and other EAE models. In addition, our analysis has identified strong correlations between different amino acids and biogenic amines that appear to change in two distinct groups during EAE. Group I analyte concentrations are increased at EAE onset and peak but then decrease in the chronic phase with a large degree of variability. Group II is composed of amino acids and biogenic amines that change in a progressive manner during EAE. The altered levels of these amino acids and biogenic amines in the disease may represent a critical pathway leading to neurodegenerative processes that are now recognized to occur in EAE and MS.
Assuntos
Aminoácidos/metabolismo , Aminas Biogênicas/metabolismo , Sistema Nervoso Central/metabolismo , Encefalomielite Autoimune Experimental/metabolismo , Aminoácidos/líquido cefalorraquidiano , Animais , Aminas Biogênicas/líquido cefalorraquidiano , Encefalomielite Autoimune Experimental/líquido cefalorraquidiano , Feminino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Although hippocampal infusions of glucose enhance memory, we have found repeatedly that septal glucose infusions impair memory when gamma-aminobutyric acid (GABA) receptors are activated. For instance, hippocampal glucose infusions reverse the memory-impairing effects of co-infusions of the GABA agonist muscimol, whereas septal glucose infusions exacerbate memory deficits produced by muscimol. One potential explanation for these deleterious effects of glucose in the septum is that there are higher levels of endogenous extracellular fluid glucose concentrations in the septum than in the hippocampus. Another hypothesis is that septal glucose infusions impair memory by increasing septal GABA synthesis or release, which is possible because elevating glucose increases GABA levels in other brain regions. To test these hypotheses, Experiment 1 quantified extracellular fluid glucose levels in the septum and hippocampus using zero net flux in vivo microdialysis procedures in conscious, freely moving rats. Experiment 2 determined whether septal infusions of glucose would increase GABA concentrations in dialysates obtained from the septum. The results of Experiment 1 indicated that extracellular fluid glucose levels in the hippocampus and septum are comparable. The results of Experiment 2 showed that co-infusions of glucose with muscimol, at doses that did not affect memory on their own, decreased percent alternation memory scores. However, none of the infusions significantly affected GABA levels. Collectively, these findings suggest that the memory-impairing effects of septal infusions of glucose are not likely due to regional differences in basal extracellular fluid glucose concentrations and are not mediated via an increase in septal GABA release.