RESUMEN
Rett Syndrome (RTT) is a genetic disorder that is caused by mutations in the x-linked gene coding for methyl-CpG-biding-protein 2 (MECP2) and that mainly affects females. Male and female transgenic mouse models of RTT have been studied extensively, and we have learned a great deal regarding RTT neuropathology and how MeCP2 deficiency may be influencing brain function and maturation. In this manuscript we review what is known concerning structural and coinciding functional and behavioral deficits in RTT and in mouse models of MeCP2 deficiency. We also introduce our own corroborating data regarding behavioral phenotype and morphological alterations in volume of the cortex and striatum and the density of neurons, aberrations in experience-dependent plasticity within the barrel cortex and the impact of MeCP2 loss on glial structure. We conclude that regional structural changes in genetic models of RTT show great similarity to the alterations in brain structure of patients with RTT. These region-specific modifications often coincide with phenotype onset and contribute to larger issues of circuit connectivity, progression, and severity. Although the alterations seen in mouse models of RTT appear to be primarily due to cell-autonomous effects, there are also non-cell autonomous mechanisms including those caused by MeCP2-deficient glia that negatively impact healthy neuronal function. Collectively, this body of work has provided a solid foundation on which to continue to build our understanding of the role of MeCP2 on neuronal and glial structure and function, its greater impact on neural development, and potential new therapeutic avenues.
Asunto(s)
Encéfalo/crecimiento & desarrollo , Síndrome de Rett/etiología , Animales , Ganglios Basales/patología , Encéfalo/fisiopatología , Modelos Animales de Enfermedad , Hipocampo/patología , Humanos , Proteína 2 de Unión a Metil-CpG/metabolismo , Ratones/crecimiento & desarrollo , Trastornos Motores/etiología , Trastornos Motores/fisiopatología , Plasticidad Neuronal , Síndrome de Rett/fisiopatología , Síndrome de Rett/psicologíaRESUMEN
After publication of the article [1], it has been brought to our attention that an author's name has been formatted incorrectly.
RESUMEN
BACKGROUND: Rett syndrome (RTT) is a pervasive developmental disorder that is progressive and has no effective cure. Immune dysregulation, oxidative stress, and excess glutamate in the brain mediated by glial dysfunction have been implicated in the pathogenesis and worsening of symptoms of RTT. In this study, we investigated a new nanotherapeutic approach to target glia for attenuation of brain inflammation/injury both in vitro and in vivo using a Mecp2-null mouse model of Rett syndrome. METHODS: To determine whether inflammation and immune dysregulation were potential targets for dendrimer-based therapeutics in RTT, we assessed the immune response of primary glial cells from Mecp2-null and wild-type (WT) mice to LPS. Using dendrimers that intrinsically target activated microglia and astrocytes, we studied N-acetyl cysteine (NAC) and dendrimer-conjugated N-acetyl cysteine (D-NAC) effects on inflammatory cytokines by PCR and multiplex assay in WT vs Mecp2-null glia. Since the cysteine-glutamate antiporter (Xc-) is upregulated in Mecp2-null glia when compared to WT, the role of Xc- in the uptake of NAC and L-cysteine into the cell was compared to that of D-NAC using BV2 cells in vitro. We then assessed the ability of D-NAC given systemically twice weekly to Mecp2-null mice to improve behavioral phenotype and lifespan. RESULTS: We demonstrated that the mixed glia derived from Mecp2-null mice have an exaggerated inflammatory and oxidative stress response to LPS stimulation when compared to WT glia. Expression of Xc- was significantly upregulated in the Mecp2-null glia when compared to WT and was further increased in the presence of LPS stimulation. Unlike NAC, D-NAC bypasses the Xc- for cell uptake, increasing intracellular GSH levels while preventing extracellular glutamate release and excitotoxicity. Systemically administered dendrimers were localized in microglia in Mecp2-null mice, but not in age-matched WT littermates. Treatment with D-NAC significantly improved behavioral outcomes in Mecp2-null mice, but not survival. CONCLUSIONS: These results suggest that delivery of drugs using dendrimer nanodevices offers a potential strategy for targeting glia and modulating oxidative stress and immune responses in RTT.
Asunto(s)
Acetilcisteína/uso terapéutico , Encéfalo/patología , Dendrímeros/uso terapéutico , Depuradores de Radicales Libres/uso terapéutico , Microglía/efectos de los fármacos , Síndrome de Rett/tratamiento farmacológico , Acetilcisteína/farmacología , Animales , Encéfalo/efectos de los fármacos , Citocinas/genética , Citocinas/metabolismo , Dendrímeros/farmacología , Modelos Animales de Enfermedad , Depuradores de Radicales Libres/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/genética , Ácido Glutámico/metabolismo , Glutatión/metabolismo , Lipopolisacáridos/farmacología , Proteína 2 de Unión a Metil-CpG/genética , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Microglía/metabolismo , Mutación/genética , Síndrome de Rett/genética , Síndrome de Rett/patología , Distribución Tisular/efectos de los fármacos , Distribución Tisular/genéticaRESUMEN
Tissue engineering (TE) aims to generate bioengineered constructs which can offer a surgical treatment for many conditions involving tissue or organ loss. Construct generation must be guided by suitable assessment tools. However, most current tools (e.g. histology) are destructive, which restricts evaluation to a single-2D anatomical plane, and has no potential for assessing constructs prior to or following their implantation. An alternative can be provided by laboratory-based x-ray phase contrast computed tomography (PC-CT), which enables the extraction of 3D density maps of an organ's anatomy. In this work, we developed a semi-automated image processing pipeline dedicated to the analysis of PC-CT slices of oesophageal constructs. Visual and quantitative (density and morphological) information is extracted on a volumetric basis, enabling a comprehensive evaluation of the regenerated constructs. We believe the presented tools can enable the successful regeneration of patient-specific oesophagus, and bring comparable benefit to a wide range of TE applications. STATEMENT OF SIGNIFICANCE: Phase contrast computed tomography (PC-CT) is an imaging modality which generates high resolution volumetric density maps of biological tissue. In this work, we demonstrate the use of PC-CT as a new tool for guiding the progression of an oesophageal tissue engineering (TE) protocol. Specifically, we developed a semi-automated image-processing pipeline which analyses the oesophageal PC-CT slices, extracting visual and quantitative (density and morphological) information. This information was proven key for performing a comprehensive evaluation of the regenerated constructs, and cannot be obtained through existing assessment tools primarily due to their destructive nature (e.g. histology). This work paves the way for using PC-CT in a wide range of TE applications which can be pivotal for unlocking the potential of this field.
Asunto(s)
Ingeniería de Tejidos , Tomografía Computarizada por Rayos X , Humanos , Procesamiento de Imagen Asistido por Computador , Microscopía de Contraste de Fase , Ingeniería de Tejidos/métodos , Tomografía Computarizada por Rayos X/métodos , Rayos XRESUMEN
Nanotechnology has the potential to open many novel diagnostic and treatment avenues for disorders of the central nervous system (CNS). In this review, we discuss recent developments in the applications of nanotechnology in CNS therapies, diagnosis and biology. Novel approaches for the diagnosis and treatment of neuroinflammation, brain dysfunction, psychiatric conditions, brain cancer, and nerve injury provide insights into the potential of nanomedicine. We also highlight nanotechnology-enabled neuroscience techniques such as electrophysiology and intracellular sampling to improve our understanding of the brain and its components. With nanotechnology integrally involved in the advancement of basic neuroscience and the development of novel treatments, combined diagnostic and therapeutic applications have begun to emerge. Nanotheranostics for the brain, able to achieve single-cell resolution, will hasten the rate in which we can diagnose, monitor, and treat diseases. Taken together, the recent advances highlighted in this review demonstrate the prospect for significant improvements to clinical diagnosis and treatment of a vast array of neurological diseases. However, it is apparent that a strong dialogue between the nanoscience and neuroscience communities will be critical for the development of successful nanotherapeutics that move to the clinic, benefit patients, and address unmet needs in CNS disorders.
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Enfermedades del Sistema Nervioso Central/tratamiento farmacológico , Nanotecnología , Fármacos Neuroprotectores/uso terapéutico , Neurociencias , Sistemas de Liberación de Medicamentos , Humanos , Nanopartículas/química , Fármacos Neuroprotectores/síntesis química , Fármacos Neuroprotectores/químicaRESUMEN
BACKGROUND: Interleukin-1alpha (IL-1) is known to radioprotect the gastrointestinal tract, but the mechanism by which this protection occurs remains unclear. These studies were undertaken to investigate whether the radioprotective potential of IL-1 may be linked to an ability to reduce apoptosis within the gastrointestinal crypts. MATERIALS AND METHODS: IL-1 was administered to C57Bl/6 mice 24 hours prior to receiving 8 Gy abdominal X-irradiation (xRT). At designated times, experimental mice were sacrificed, jejunal tissue removed, and paraffin-embedded sections analyzed for apoptosis indices (AI) and immunohistochemical determination of active caspase-3, -8 and -9. RESULTS: AI data demonstrated that 8 Gy irradiation resulted in a marked jejunal apoptotic response, but IL-1 pretreatment significantly attenuated this response. Concomitant with this attenuation, reduced levels of caspase-3 and 9, but not caspase-8, activation were observed, particularly within goblet cells. CONCLUSION: The results outlined herein suggest that radioprotection by IL-1 is mediated, at least in part, through a reduction in the apoptotic response which appears to involve down-regulation of the intrinsic apoptotic pathway.
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Apoptosis/efectos de los fármacos , Apoptosis/efectos de la radiación , Interleucina-1alfa/farmacología , Yeyuno/efectos de los fármacos , Yeyuno/efectos de la radiación , Protectores contra Radiación/farmacología , Animales , Caspasas/metabolismo , Modelos Animales de Enfermedad , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/efectos de la radiación , Activación Enzimática/efectos de la radiación , Femenino , Técnicas In Vitro , Isoenzimas/metabolismo , Yeyuno/enzimología , Yeyuno/patología , Ratones , Ratones Endogámicos C57BL , Traumatismos Experimentales por Radiación/patología , Traumatismos Experimentales por Radiación/prevención & controlRESUMEN
Recently, alternative drug therapies for Parkinson's disease (PD) have been investigated as there are many shortcomings of traditional dopamine-based therapies including difficulties in treating cognitive and attentional dysfunction. A promising therapeutic avenue is to target mitochondrial dysfunction and oxidative stress in PD. One option might be the use of methylene blue (MB), an antioxidant and metabolic enhancer. MB has been shown to improve cognitive function in both intact rodents and rodent disease models. Therefore, we investigated whether MB might treat attentional deficits in a rat model of PD induced by 6-hydroxydopamine (6-OHDA). MB also has neuroprotective capabilities against neurotoxic insult, so we also assessed the ability of MB to provide neuroprotection in our PD model. The results show that MB could preserve some dopamine neurons in the substantia nigra par compacta when 6-OHDA was infused into the medial forebrain bundle. This neuroprotection did not yield a significant behavioral improvement when motor functions were measured. However, MB significantly improved attentional performance in the five-choice task designed to measure selective and sustained attention. In conclusion, MB might be useful in improving some attentional function and preserving dopaminergic cells in this model. Future work should continue to study and optimize the abilities of MB for the treatment of PD.
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Atención/efectos de los fármacos , Neuronas Dopaminérgicas/efectos de los fármacos , Neuronas Dopaminérgicas/metabolismo , Azul de Metileno/administración & dosificación , Fármacos Neuroprotectores/administración & dosificación , Trastornos Parkinsonianos/metabolismo , Trastornos Parkinsonianos/psicología , Animales , Antioxidantes/administración & dosificación , Conducta Animal , Dopamina/metabolismo , Masculino , Trastornos Parkinsonianos/tratamiento farmacológico , Ratas Sprague-Dawley , Sustancia Negra/efectos de los fármacos , Sustancia Negra/metabolismo , Tirosina 3-Monooxigenasa/metabolismo , Área Tegmental Ventral/efectos de los fármacos , Área Tegmental Ventral/metabolismoRESUMEN
Attentional deficits including difficulty in switching attention between tasks or rules, sustaining attention, and selectively attending to specific stimuli are commonly seen in patients with Parkinson's disease (PD). While these deficits are frequently reported, it is unclear how traditional dopamine replacement therapy such as l-dopa affects these deficits. In a rat model of PD in which dopamine is unilaterally depleted with a 6-hydroxydopamine infusion to the medial forebrain bundle, we first examined the impact of acute and chronic l-dopa treatment on attention switching as modeled by disengagement behavior (i.e. the ability to disengage from an on-going behavior such as eating or drinking to attend to perioral stimulation). Then, in a separate experiment, we evaluated the effects of l-dopa treatment on selective and sustained attention deficits using a five choice task. Our data suggest that the l-dopa dose necessary to recover motor function can successfully restore attention switching behavior (i.e. disengagement behavior), but further worsens performance in the selective and sustained attention task. Furthermore, this same dose was responsible for inducing dyskinesias in rats given chronic daily injections. Taken together, these findings demonstrate that dopamine replacement therapy may not be sufficient for treating all types of attentional dysfunction occurring in PD.
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Antiparkinsonianos/farmacología , Discinesia Inducida por Medicamentos/tratamiento farmacológico , Levodopa/farmacología , Haz Prosencefálico Medial/efectos de los fármacos , Oxidopamina/farmacología , Enfermedad de Parkinson/tratamiento farmacológico , Animales , Atención/efectos de los fármacos , Conducta Animal/efectos de los fármacos , Cuerpo Estriado/efectos de los fármacos , Modelos Animales de Enfermedad , Dopamina/farmacología , Masculino , Actividad Motora/efectos de los fármacos , Enfermedad de Parkinson/fisiopatología , Ratas Sprague-DawleyRESUMEN
Central nervous system (CNS) tuberculosis (TB) is the most severe form of extra-pulmonary TB and disproportionately affects young children where the developing brain has a unique host response. New Zealand white rabbits were infected with Mycobacterium tuberculosis via subarachnoid inoculation at postnatal day 4-8 and evaluated until 4-6â weeks post-infection. Control and infected rabbit kits were assessed for the development of neurological deficits, bacterial burden, and postmortem microbiologic and pathologic changes. The presence of meningitis and tuberculomas was demonstrated histologically and by in vivo magnetic resonance imaging (MRI). The extent of microglial activation was quantified by in vitro immunohistochemistry as well as non-invasive in vivo imaging of activated microglia/macrophages with positron emission tomography (PET). Subarachnoid infection induced characteristic leptomeningeal and perivascular inflammation and TB lesions with central necrosis, a cellular rim and numerous bacilli on pathologic examination. Meningeal and rim enhancement was visible on MRI. An intense microglial activation was noted in M. tuberculosis-infected animals in the white matter and around the TB lesions, as evidenced by a significant increase in uptake of the tracer 124I-DPA-713, which is specific for activated microglia/macrophages, and confirmed by quantification of Iba-1 immunohistochemistry. Neurobehavioral analyses demonstrated signs similar to those noted in children with delayed maturation and development of neurological deficits resulting in significantly worse composite behavior scores in M. tuberculosis-infected animals. We have established a rabbit model that mimics features of TB meningitis in young children. This model could provide a platform for evaluating novel therapies, including host-directed therapies, against TB meningitis relevant to a young child's developing brain.
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Microglía/patología , Tuberculosis Meníngea/patología , Acetamidas/química , Animales , Conducta Animal , Encéfalo/microbiología , Encéfalo/patología , Niño , Modelos Animales de Enfermedad , Exudados y Transudados , Femenino , Gadolinio/química , Humanos , Inflamación/patología , Radioisótopos de Yodo/química , Cinética , Pulmón/microbiología , Pulmón/patología , Activación de Macrófagos , Imagen por Resonancia Magnética , Masculino , Actividad Motora , Mycobacterium tuberculosis/crecimiento & desarrollo , Tomografía Computarizada por Tomografía de Emisión de Positrones , Pirazoles/química , Pirimidinas/química , Conejos , Tuberculosis Meníngea/diagnóstico por imagen , Tuberculosis Meníngea/microbiología , Tuberculosis Meníngea/fisiopatologíaRESUMEN
The central amygdala (CeA) has been shown to play an important role in mediating several attentional processes, including selective and sustained attention. Emerging evidence suggests that the connections between the CeA and the midbrain dopamine areas are important for attentional processing. However, little is known about the role of dopaminergic input into the CeA in mediating attentional processes. To investigate how dopamine activity in the CeA modulates attentional processing, CeA D1 and D2 receptors were temporarily inactivated during testing in a 5-choice task. In this task, rats were trained to detect 1 of 5 recessed ports that briefly illuminated in order to receive a food reward, therefore requiring the rats to successfully sustain their attention to monitor all 5 ports and selectively attend to the lit port. Then, rats were tested in several altered versions of the task to increase attentional load (e.g., variable ready period). In 2 experiments, the D1 antagonist CH 23390 or the D2 antagonist raclopride were infused into the bilateral CeA preceding the test sessions. D1, but not D2, inactivation reduced performance in the more demanding versions of the 5-choice task. Therefore, CeA D1 receptors might mediate attentional functions important for visual cue detection in a 5-choice task.
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Atención/fisiología , Núcleo Amigdalino Central/fisiología , Receptores de Dopamina D1/fisiología , Receptores de Dopamina D2/fisiología , Animales , Atención/efectos de los fármacos , Núcleo Amigdalino Central/efectos de los fármacos , Núcleo Amigdalino Central/metabolismo , Conducta de Elección/efectos de los fármacos , Conducta de Elección/fisiología , Condicionamiento Operante , Dopamina/metabolismo , Antagonistas de los Receptores de Dopamina D2/farmacología , Masculino , Racloprida/farmacología , Ratas , Ratas Long-Evans , Receptores de Dopamina D1/antagonistas & inhibidores , Receptores de Dopamina D1/metabolismo , Receptores de Dopamina D2/metabolismo , RecompensaRESUMEN
Unilateral nigrostriatal dopamine depletion in animals induces contralateral sensorimotor deficits that are like symptoms associated with Parkinson's disease (PD). Unilateral nigrostriatal dopamine depletion also causes a contralateral deficit in disengagement behavior (e.g., ability to stop an ongoing activity to orient/attend to a new stimulus). This disengagement deficit has been shown to be resistant to treatments that rescued other motor and somatosensory deficits. Thus, disengagement behavior may involve unique sensorimotor information integration potentially important for attentional allocation and may rely strongly on a mechanism that includes extranigrostriatal circuitry. The central nucleus of the amygdala (CeA) and its connections with the nigral dopamine system have been reported to modulate cognitive processes dependent substantially on attentional allocation. CeA dopamine function might be also important for disengagement behavior. In Experiment 1, rats received microinfusions of 6-hydroxydopamine unilaterally to induce dopamine terminal loss in the CeA and were tested for disengagement behavior in addition to several sensorimotor functions. These rats showed deficits in contralateral disengagement behavior and an asymmetry in adhesive dot removal from the paws, but not in forelimb use in a cylinder or amphetamine rotation. In Experiment 2, rats received D1 or D2 antagonists into the CeA unilaterally prior to behavioral tests. The D1 antagonist disrupted disengagement behavior without affecting the other sensorimotor tests examined. The D2 antagonist had no effects on any of the behaviors tested. Our results suggest that CeA dopamine function is involved in modulation of disengagement behavior.