RESUMO
Polyamines have fundamental roles in brain homeostasis as key modulators of cellular excitability. Several studies have suggested alterations in polyamine metabolism in stress related disorders, suicide, depression, and neurodegeneration, making the pharmacological modulation of polyamines a highly appealing therapeutic strategy. Polyamines are small aliphatic molecules that can modulate cationic channels involved in neuronal excitability. Previous indirect evidence has suggested that polyamines can modulate anionic GABAA receptors (GABAARs), which mediate inhibitory signaling and provide a direct route to reduce hyperexcitability. Here, we attempted to characterize the effect that spermine, the polyamine with the strongest reported effect on GABAARs, has on human postmortem native GABAARs. We microtransplanted human synaptic membranes from the dorsolateral prefrontal cortex of four cases with no history of mental or neurological disorders, and directly recorded spermine effects on ionic GABAARs responses on microtransplanted oocytes. We show that in human synapses, inhibition of GABAARs by spermine was better explained by alkalization of the extracellular solution. Additionally, spermine had no effect on the potentiation of GABA-currents by diazepam, indicating that even if diazepam binding is enhanced by spermine, it does not translate to changes in functional activity. Our results clearly demonstrate that while extracellular spermine does not have direct effects on human native synaptic GABAARs, spermine-mediated shifts of pH inhibit GABAARs. Potential spermine-mediated increase of pH in synapses in vivo may therefore participate in increased neuronal activity observed during physiological and pathological states, and during metabolic alterations that increase the release of spermine to the extracellular milieu.
Assuntos
Córtex Pré-Frontal/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Espermina/farmacologia , Sinapses/efeitos dos fármacos , Membranas Sinápticas/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Oócitos/efeitos dos fármacos , Oócitos/metabolismo , Córtex Pré-Frontal/metabolismo , Sinapses/metabolismo , Membranas Sinápticas/metabolismoRESUMO
The CLARITY technique enables three-dimensional visualization of fluorescent-labeled biomolecules in clarified intact brain samples, affording a unique view of molecular neuroanatomy and neurocircuitry. It is therefore, essential to find the ideal combination for clearing tissue and detecting the fluorescent-labeled signal. This method requires the formation of a formaldehyde-acrylamide fixative-generated hydrogel mesh through which cellular lipid is removed with sodium dodecyl sulfate. Several laboratories have used differential acrylamide and detergent concentrations to achieve better tissue clearing and antibody penetration, but the potential effects upon fluorescent signal retention is largely unknown. In an effort to optimize CLARITY processing procedures we performed quantitative parvalbumin immunofluorescence and lectin-based vasculature staining using either 4 or 8% sodium dodecyl sulfate detergent in combination with different acrylamide formulas in mouse brain slices. Using both confocal and CLARITY-optimized lightsheet microscope-acquired images, we demonstrate that 2% acrylamide monomer combined with 0.0125% bis-acrylamide and cleared with 4% sodium dodecyl sulfate generally provides the most optimal signal visualization amongst various hydrogel monomer concentrations, lipid removal times, and detergent concentrations.
Assuntos
Acrilamida/metabolismo , Encéfalo/anatomia & histologia , Imunofluorescência/métodos , Lectinas/metabolismo , Animais , Encéfalo/metabolismo , Relação Dose-Resposta a Droga , Imageamento Tridimensional , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Parvalbuminas/metabolismo , Coloração e Rotulagem/métodos , Fatores de TempoRESUMO
Stress can be a predisposing factor to psychiatric disorders and has been associated with decreased neurogenesis and reduced hippocampal volume especially in depression. Similarly, in white blood cells chronic psychological stress has been associated with telomere shortening and with mood disorders and schizophrenia (SZ). However, in previous post-mortem brain studies from occipital cortex and cerebellum, no difference in telomere length was observed in depression. We hypothesized that in psychiatric disorders, stress-driven accelerated cellular aging can be observed in brain regions particularly sensitive to stress. Telomere length was measured by quantitative-PCR in five brain regions (dorsolateral prefrontal cortex, hippocampus (HIPP), amygdala, nucleus accumbens and substantia nigra (SN)) in major depressive disorder (MDD), bipolar disorder, SZ and normal control subjects (N = 40, 10 subjects per group). We observed significant differences in telomere length across brain regions suggesting variable levels of cell aging, with SN and HIPP having the longest telomeres and the dorsolateral prefrontal cortex the shortest. A significant decrease (P < 0.02) in telomere length was observed specifically in the HIPP of MDD subjects even after controlling for age. In the HIPP of MDD subjects, several genes involved in neuroprotection and in stress response (FKBP5, CRH) showed altered levels of mRNA. Our results suggest the presence of hippocampal stress-mediated accelerated cellular aging in depression. Further studies are needed to investigate the cellular specificity of these findings.
Assuntos
Transtorno Depressivo Maior/genética , Transtorno Depressivo Maior/patologia , Hipocampo/patologia , Telômero/genética , Telômero/patologia , Análise de Variância , Encéfalo/patologia , Cadáver , Dissecação , Feminino , Técnicas Genéticas , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da PolimeraseRESUMO
Conventional antidepressants require 2-8 weeks for a full clinical response. In contrast, two rapidly acting antidepressant interventions, low-dose ketamine and sleep deprivation (SD) therapy, act within hours to robustly decrease depressive symptoms in a subgroup of major depressive disorder (MDD) patients. Evidence that MDD may be a circadian-related illness is based, in part, on a large set of clinical data showing that diurnal rhythmicity (sleep, temperature, mood and hormone secretion) is altered during depressive episodes. In a microarray study, we observed widespread changes in cyclic gene expression in six regions of postmortem brain tissue of depressed patients matched with controls for time-of-death (TOD). We screened 12 000 transcripts and observed that the core clock genes, essential for controlling virtually all rhythms in the body, showed robust 24-h sinusoidal expression patterns in six brain regions in control subjects. In MDD patients matched for TOD with controls, the expression patterns of the clock genes in brain were significantly dysregulated. Some of the most robust changes were seen in anterior cingulate (ACC). These findings suggest that in addition to structural abnormalities, lesion studies, and the large body of functional brain imaging studies reporting increased activation in the ACC of depressed patients who respond to a wide range of therapies, there may be a circadian dysregulation in clock gene expression in a subgroup of MDDs. Here, we review human, animal and neuronal cell culture data suggesting that both low-dose ketamine and SD can modulate circadian rhythms. We hypothesize that the rapid antidepressant actions of ketamine and SD may act, in part, to reset abnormal clock genes in MDD to restore and stabilize circadian rhythmicity. Conversely, clinical relapse may reflect a desynchronization of the clock, indicative of a reactivation of abnormal clock gene function. Future work could involve identifying specific small molecules capable of resetting and stabilizing clock genes to evaluate if they can rapidly relieve symptoms and sustain improvement.
Assuntos
Antidepressivos/uso terapêutico , Proteínas CLOCK/genética , Transtornos Cronobiológicos/complicações , Transtornos Cronobiológicos/genética , Transtorno Depressivo Maior , Animais , Transtorno Depressivo Maior/etiologia , Transtorno Depressivo Maior/genética , Transtorno Depressivo Maior/terapia , Antagonistas de Aminoácidos Excitatórios/uso terapêutico , Giro do Cíngulo/metabolismo , Humanos , Ketamina/uso terapêutico , Privação do SonoRESUMO
Several studies have proposed that brain glutamate signaling abnormalities and glial pathology have a role in the etiology of major depressive disorder (MDD). These conclusions were primarily drawn from post-mortem studies in which forebrain brain regions were examined. The locus coeruleus (LC) is the primary source of extensive noradrenergic innervation of the forebrain and as such exerts a powerful regulatory role over cognitive and affective functions, which are dysregulated in MDD. Furthermore, altered noradrenergic neurotransmission is associated with depressive symptoms and is thought to have a role in the pathophysiology of MDD. In the present study we used laser-capture microdissection (LCM) to selectively harvest LC tissue from post-mortem brains of MDD patients, patients with bipolar disorder (BPD) and from psychiatrically normal subjects. Using microarray technology we examined global patterns of gene expression. Differential mRNA expression of select candidate genes was then interrogated using quantitative real-time PCR (qPCR) and in situ hybridization (ISH). Our findings reveal multiple signaling pathway alterations in the LC of MDD but not BPD subjects. These include glutamate signaling genes, SLC1A2, SLC1A3 and GLUL, growth factor genes FGFR3 and TrkB, and several genes exclusively expressed in astroglia. Our data extend previous findings of altered glutamate, astroglial and growth factor functions in MDD for the first time to the brainstem. These findings indicate that such alterations: (1) are unique to MDD and distinguishable from BPD, and (2) affect multiple brain regions, suggesting a whole-brain dysregulation of such functions.
Assuntos
Transtorno Depressivo Maior/patologia , Regulação da Expressão Gênica , Ácido Glutâmico/metabolismo , Locus Cerúleo/metabolismo , Neuroglia/metabolismo , Transdução de Sinais/fisiologia , Adolescente , Adulto , Idoso , Feminino , Perfilação da Expressão Gênica/métodos , Proteínas de Transporte de Glutamato da Membrana Plasmática , Ácido Glutâmico/genética , Humanos , Peptídeos e Proteínas de Sinalização Intercelular , Locus Cerúleo/patologia , Masculino , Microdissecção , Pessoa de Meia-Idade , Modelos Biológicos , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos/métodos , RNA Mensageiro/metabolismo , Adulto JovemAssuntos
Transtornos Mentais/terapia , Psiquiatria/tendências , Antidepressivos/uso terapêutico , Antipsicóticos/uso terapêutico , Mapeamento Encefálico , Transtorno Depressivo/terapia , Humanos , Transtornos Mentais/diagnóstico , Transtornos Mentais/etiologia , Cooperação do Paciente , Pesquisa , Esquizofrenia/tratamento farmacológico , Transtornos Relacionados ao Uso de Substâncias/tratamento farmacológicoAssuntos
Transtornos Mentais , Psiquiatria/tendências , Antipsicóticos/uso terapêutico , Benzodiazepinas , Humanos , Aprendizagem/fisiologia , Transtornos Mentais/etiologia , Transtornos Mentais/terapia , Neuroanatomia , Olanzapina , Personalidade/genética , Pirenzepina/análogos & derivados , Pirenzepina/uso terapêuticoRESUMO
This special section represents a coordinated publication of the Journal of Consulting and Clinical Psychology and the Archives of General Psychiatry. These 2 journals have typically focused on somewhat different areas of research and have been read by different audiences. In an effort to achieve cross-fertilization of the disciplines of psychiatry and clinical psychology, this coordinated publication provides a current view of research both in psychopharmacology and psychotherapy as applied to major depression, anxiety disorders, alcohol abuse, and drug abuse. To further the aims of informing the diverse readership in areas to which they are often not exposed in the separate journals, the Journal of Consulting and Clinical Psychology is publishing in this section, articles that address biomedical and psychopharmacological research, and the Archives of General Psychiatry is publishing a coordinated set of articles on psychotherapy and behavior therapy. Collectively, the series contained in these 2 journals is designed both to foster knowledge and to enhance communication among psychiatrists and psychologists.
Assuntos
Tratamento Farmacológico , Serviços de Saúde Mental , Psicoterapia , Pesquisa , Humanos , National Institute of Mental Health (U.S.) , Estados UnidosAssuntos
Transtornos Mentais/tratamento farmacológico , Transtornos Mentais/terapia , National Health Insurance, United States , Psicoterapia , Psicotrópicos/uso terapêutico , Custos de Cuidados de Saúde , Política de Saúde , Pesquisa sobre Serviços de Saúde , Humanos , Serviços de Saúde Mental/economia , Serviços de Saúde Mental/normas , Qualidade da Assistência à Saúde , Estados UnidosRESUMO
In 1994, the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) was published. Two studies suggested that the prevalence of psychiatric disorders may have been underestimated. A susceptibility gene for manic-depressive illness has been reported.
Assuntos
Psiquiatria/tendências , Humanos , Transtornos Mentais/etiologia , Transtornos Mentais/terapia , Estados UnidosRESUMO
The heterogeneity of neural gene expression and the spatially limited expression of many low-abundance messenger RNAs in the brain has made cloning and analysis of such messages difficult. To generate amounts of nucleic acids sufficient for use in standard cloning strategies, we have devised a method for producing amplified heterogeneous populations of RNA from limited quantities of cDNA. Whole cerebellar RNA was primed with a synthetic oligonucleotide containing the T7 RNA polymerase promoter sequence 5' to a polythymidylate region. After second-strand cDNA synthesis, T7 RNA polymerase was used to generate amplified antisense RNA (aRNA). Up to 80-fold molar amplification has been achieved from nanogram quantities of cDNA. The amplified material is similar in size distribution to the parent cDNA and shows sequence heterogeneity as assessed by Southern and Northern blot analysis. Specific messages for moderate-abundance mRNAs for actin and guanine nucleotide-binding protein (G-protein) alpha subunits have been detected in the amplified material. By using in situ transcription to generate cDNA, sequences for cyclophilin have been detected in aRNA derived from single cerebellar tissue sections. cDNA derived from a single cerebellar Purkinje cell also has been amplified and yields material that hybridizes to cognate whole RNA and mRNA but not to Escherichia coli RNA.
Assuntos
Cerebelo/metabolismo , DNA/genética , RNA/genética , Actinas/genética , Animais , Sequência de Bases , Northern Blotting , Southern Blotting , Proteínas de Ligação ao GTP/genética , Técnicas Genéticas , Dados de Sequência Molecular , Sondas de Oligonucleotídeos , RNA/biossíntese , RNA Mensageiro/genética , Ratos , Transcrição GênicaRESUMO
The effects of maternal proximity on the behavioral and physiological responses of infant rhesus macaques during 4 days of total or adjacent separations from the mother were studied. The 6 infants tested showed behavioral responses that differentiated the two separation conditions. Major differences were found in the quantity and quality of vocalizations, the occurrence of cage-biting and cage-shaking behavior, object exploration, and hunched and freezing postures. In particular, the structure of coo vocalizations clearly discriminated between the presence or the absence of the mother during separation. Cerebrospinal fluid (CSF) concentrations of dopamine and serotonin metabolites did not discriminate between the two separation conditions but showed a transient elevation at 24 hr after separation and were not different from baseline by 96 hr after separation. In contrast, both the plasma cortisol and the CSF norepinephrine metabolite responses tended to be greater and to persist for a longer period of time when infants were totally isolated. The results are discussed within the context of attachment and coping theories.
Assuntos
Nível de Alerta/fisiologia , Comportamento Animal/fisiologia , Privação Materna , Animais , Feminino , Ácido Homovanílico/líquido cefalorraquidiano , Hidrocortisona/sangue , Ácido Hidroxi-Indolacético/líquido cefalorraquidiano , Macaca mulatta , Masculino , Metoxi-Hidroxifenilglicol/líquido cefalorraquidiano , Espectrografia do Som , Vocalização Animal/fisiologiaRESUMO
Lumbar cerebrospinal fluid concentrations of phenylacetic acid were significantly elevated in paranoid vs. nonparanoid schizophrenics. Further, phenylacetic acid concentrations were correlated with hostility. These results are consistent with the hypothesis that phenylethylamine, the proposed precursor of phenylacetic acid, plays a role in schizophrenia.