RESUMEN
We previously showed that, in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease (PD), vaccination with bacillus Calmette-Guerin (BCG) prior to MPTP exposure limited the loss of striatal dopamine (DA) and dopamine transporter (DAT) and prevented the activation of nigral microglia. Here, we conducted BCG dose studies and investigated the mechanisms underlying BCG vaccination's neuroprotective effects in this model. We found that a dose of 1 × 10(6) cfu BCG led to higher levels of striatal DA and DAT ligand binding (28% and 42%, respectively) in BCG-vaccinated vs. unvaccinated MPTP-treated mice, but without a significant increase in substantia nigra tyrosine hydroxylase-staining neurons. Previous studies showed that BCG can induce regulatory T cells (Tregs) and that Tregs are neuroprotective in models of neurodegenerative diseases. However, MPTP is lymphotoxic, so it was unclear whether Tregs were maintained after MPTP treatment and whether a relationship existed between Tregs and the preservation of striatal DA system integrity. We found that, 21 days post-MPTP treatment, Treg levels in mice that had received BCG prior to MPTP were threefold greater than those in MPTP-only-treated mice and elevated above those in saline-only-treated mice, suggesting that the persistent BCG infection continually promoted Treg responses. Notably, the magnitude of the Treg response correlated positively with both striatal DA levels and DAT ligand binding. Therefore, BCG vaccine-mediated neuroprotection is associated with Treg levels in this mouse model. Our results suggest that BCG-induced Tregs could provide a new adjunctive therapeutic approach to ameliorating pathology associated with PD and other neurodegenerative diseases.
Asunto(s)
Vacuna BCG/inmunología , Fármacos Neuroprotectores/inmunología , Trastornos Parkinsonianos/inmunología , Trastornos Parkinsonianos/prevención & control , Linfocitos T Reguladores/inmunología , Animales , Vacuna BCG/administración & dosificación , Encéfalo/inmunología , Encéfalo/patología , Cromatografía Líquida de Alta Presión , Modelos Animales de Enfermedad , Citometría de Flujo , Masculino , Ratones , Ratones Endogámicos C57BL , Fármacos Neuroprotectores/administración & dosificaciónRESUMEN
The continuing spread of methamphetamine (METH) abuse has stimulated research aimed at understanding consequences of its prolonged exposure. Alterations in nigrostriatal dopamine (DA) system parameters have been characterized in experimental studies after discontinuation of long-term METH but fewer studies have included similar assessments during METH exposure. Here, we report METH plasma pharmacokinetics and striatal DA system alterations in rat after noncontingent and contingent METH administration for 7.5 weeks. Escalating METH exposure was delivered by dynamic infusion (DI) that incorporated a "humanized" plasma METH half life or by intravenous self-administration (IVSA) that included binge intakes. Kinetic modeling of DI and IVSA for 24 h periods during the final week of METH exposure showed that plasma METH levels remained between 0.7 and 1.5 µM. Animals were sacrificed during their last METH administration for autoradiography assessment using [³H]ligands and D2 agonist-induced [³5S]GTPγS binding. DA transporter binding was decreased (DI, 34%; IVSA, 15%) while vesicular monoamine transporter binding and substantia nigra DA cell numbers were unchanged. Decreases were measured for D2 receptor (DI and IVSA, 15-20%) and [³5S]GTPγS binding (DI, 35%; IVSA, 18%). These similar patterns of DI and IVSA associated decreases in striatal DA markers reflect consequences of cumulative METH exposure and not the drug delivery method. For METH IVSA, individual differences were observed, yet each animal's total intake was similar within and across three 24-h binges. IVSA rodent models may be useful for identifying molecular mechanisms that are associated with METH binges in humans.
Asunto(s)
Cuerpo Estriado/efectos de los fármacos , Dopaminérgicos/farmacología , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/metabolismo , Metanfetamina/farmacología , Receptores de Dopamina D2/metabolismo , Animales , Cuerpo Estriado/metabolismo , Dopaminérgicos/administración & dosificación , Dopaminérgicos/farmacocinética , Agonistas de Dopamina/farmacología , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Infusiones Intravenosas , Inyecciones Intravenosas , Masculino , Metanfetamina/administración & dosificación , Metanfetamina/farmacocinética , Ensayo de Unión Radioligante , Ratas , Ratas Sprague-Dawley , Sustancia Negra/efectos de los fármacos , Sustancia Negra/metabolismo , Radioisótopos de Azufre , Tritio , Proteínas de Transporte Vesicular de Monoaminas/metabolismoRESUMEN
A prototype Low Intensity Focused Ultrasound (LIFU) stimulator system was developed to evaluate non-invasive neuromodulation in a large animal model. We conducted a feasibility study on a Göttingen minipig, demonstrating reversible, targeted transcranial neuromodulation. The hypothalamus of the minipig was repeatedly stimulated with LIFU which evoked temporally correlated increases in both heart rate and blood pressure.
Asunto(s)
Simulación por Computador , Hipotálamo/diagnóstico por imagen , Ultrasonido/métodos , Ultrasonografía/métodos , Animales , Estudios de Factibilidad , Modelos Animales , PorcinosRESUMEN
Prior studies of appetite regulatory networks, primarily in rodents, have established that targeted electrical stimulation of ventromedial hypothalamus (VMH) can alter food intake patterns and metabolic homeostasis. Consideration of this method for weight modulation in humans with severe overeating disorders and morbid obesity can be further advanced by modeling procedures and assessing endpoints that can provide preclinical data on efficacy and safety. In this study we adapted human deep brain stimulation (DBS) stereotactic methods and instrumentation to demonstrate in a large animal model the modulation of weight gain with VMH-DBS. Female Göttingen minipigs were used because of their dietary habits, physiologic characteristics, and brain structures that resemble those of primates. Further, these animals become obese on extra-feeding regimens. DBS electrodes were first bilaterally implanted into the VMH of the animals (nâ=â8) which were then maintained on a restricted food regimen for 1 mo following the surgery. The daily amount of food was then doubled for the next 2 mo in all animals to produce obesity associated with extra calorie intake, with half of the animals (nâ=â4) concurrently receiving continuous low frequency (50 Hz) VMH-DBS. Adverse motoric or behavioral effects were not observed subsequent to the surgical procedure or during the DBS period. Throughout this 2 mo DBS period, all animals consumed the doubled amount of daily food. However, the animals that had received VMH-DBS showed a cumulative weight gain (6.1±0.4 kg; mean ± SEM) that was lower than the nonstimulated VMH-DBS animals (9.4±1.3 kg; p<0.05), suggestive of a DBS-associated increase in metabolic rate. These results in a porcine obesity model demonstrate the efficacy and behavioral safety of a low frequency VMH-DBS application as a potential clinical strategy for modulation of body weight.
Asunto(s)
Estimulación Encefálica Profunda/métodos , Hipotálamo , Obesidad/fisiopatología , Obesidad/terapia , Aumento de Peso , Animales , Conducta Animal , Glucemia/metabolismo , Dieta , Modelos Animales de Enfermedad , Femenino , Humanos , Imagen por Resonancia Magnética , Obesidad/sangre , Obesidad/cirugía , Reproducibilidad de los Resultados , PorcinosRESUMEN
There is a growing interest in using vaccination with CNS antigens to induce autoreactive T cell responses that home to damaged areas in the CNS and ameliorate neurodegenerative disease. Neuroprotective vaccine studies have focused on administering oligodendrocyte antigens or Copaxone® in complete Freund's adjuvant (CFA). Theoretical considerations, however, suggest that vaccination with a neuronal antigen may induce more robust neuroprotective immune responses. We assessed the neuroprotective potential of vaccines containing tyrosine hydroxylase (a neuronal protein involved in dopamine synthesis) or Copaxone® in CFA in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease. Surprisingly, we observed that the main beneficial factor in these vaccines was the CFA. Since the major immunogenic component in CFA is Mycobacterium tuberculosis, which closely related to the bacille Calmette-Guérin (BCG) that is used in human vaccines, we tested BCG vaccination in the MPTP mouse model. We observed that BCG vaccination partially preserved markers of striatal dopamine system integrity and prevented an increase in activated microglia in the substantia nigra of MPTP-treated mice. These results support a new neuroprotective vaccine paradigm in which general (nonself-reactive) immune stimulation in the periphery can limit potentially deleterious microglial responses to a neuronal insult and exert a neurorestorative effect in the CNS. Accordingly, BCG vaccination may provide a new strategy to augment current treatments for a wide range of neuropathological conditions.
Asunto(s)
Vacuna BCG/farmacología , Fármacos Neuroprotectores , Enfermedad de Parkinson/terapia , Animales , Vacuna BCG/uso terapéutico , Cuerpo Estriado , Modelos Animales de Enfermedad , Dopamina , Ratones , Sustancia Negra , Tirosina 3-Monooxigenasa/uso terapéutico , VacunaciónRESUMEN
Bingeing is one pattern of high-dose methamphetamine (METH) abuse, which involves continuous drug taking over several days and can result in psychotic behaviors for which the brain pathology remains poorly defined. A corresponding animal model of this type of METH exposure may provide novel insights into the neurochemical and behavioral sequelae associated with this condition. Accordingly, to simulate the pharmacokinetic profile of a human METH binge exposure in rats, we used a computer-controlled, intravenous METH procedure (dynamic infusion, DI) to overcome species differences in METH pharmacokinetics and to replicate the human 12-h plasma METH half-life. Animals were treated over 13 weeks with escalating METH doses, using DI, and then exposed to a binge in which drug was administered every 3 h for 72 h. Throughout the binge, behavioral effects included unabated intense oral stereotypies in the absence of locomotion and in the absence of sleep. Decrements in regional brain dopamine, norepinephrine, and serotonin levels, measured at 1 and 10 h after the last injection of the binge, had, with the exception of caudate-putamen dopamine and frontal cortex serotonin, recovered by 48 h. At 10 h after the last injection of the binge, [(3)H]ligand binding to dopamine and vesicular monoamine transporters in caudate-putamen were reduced by 35 and 13%, respectively. In a separate METH binge-treated cohort, post-binge behavioral alterations were apparent in an attenuated locomotor response to a METH challenge infusion at 24 h after the last injection of the binge. Collectively, the changes we characterized during and after a METH binge suggest that for human beings under similar exposure conditions, multiple time-dependent neurochemical deficits contribute to their behavioral profiles.
Asunto(s)
Trastornos Relacionados con Anfetaminas/fisiopatología , Estimulantes del Sistema Nervioso Central/farmacocinética , Metanfetamina/farmacocinética , Animales , Encéfalo/efectos de los fármacos , Encéfalo/fisiopatología , Estimulantes del Sistema Nervioso Central/administración & dosificación , Estimulantes del Sistema Nervioso Central/farmacología , Modelos Animales de Enfermedad , Dopamina/metabolismo , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/metabolismo , Humanos , Masculino , Metanfetamina/administración & dosificación , Metanfetamina/farmacología , Actividad Motora/efectos de los fármacos , Actividad Motora/fisiología , Norepinefrina/metabolismo , Distribución Aleatoria , Ratas , Ratas Sprague-Dawley , Serotonina/metabolismo , Sueño/efectos de los fármacos , Sueño/fisiología , Factores de Tiempo , Proteínas de Transporte Vesicular de Monoaminas/metabolismoRESUMEN
PURPOSE: Pretreatment with cyclosporine, a P-glycoprotein (P-gp) modulator increases brain uptake of 4-(2'-methoxyphenyl)-1-[2'-(N-2"-pyridinyl)-p-[(18)F]fluorobenzamido]ethylpiperazine ([(18)F]MPPF) for binding to hydroxytryptamine(1A) (5-HT(1A)) receptors. Those increases were quantified in rat brain with in vivo microPET and ex vivo tissue studies. MATERIALS AND METHODS: Each Sprague-Dawley rat (n = 4) received a baseline [(18)F]MPPF microPET scan followed by second scan 2-3 weeks later that included cyclosporine pretreatment (50 mg/kg, i.p.). Maximum a posteriori reconstructed images and volumetric ROIs were used to generate dynamic radioactivity concentration measurements for hippocampus, striatum, and cerebellum, with simplified reference tissue method (SRTM) analysis. Western blots were used to semiquantify P-gp regional distribution in brain. RESULTS: MicroPET studies showed that hippocampus uptake of [(18)F]MPPF was increased after cyclosporine; ex vivo studies showed similar increases in hippocampus and frontal cortex at 30 min, and for heart and kidney at 2.5 and 5 min, without concomitant increases in [(18)F]MPPF plasma concentration. P-gp content in cerebellum was twofold higher than in hippocampus or frontal cortex. CONCLUSIONS: These studies confirm and extend prior ex vivo results (J. Passchier, et al., Eur J Pharmacol, 2000) that showed [(18)F]MPPF as a substrate for P-gp. Our microPET results showed that P-gp modulation of [(18)F]MPPF binding to 5-HT(1A) receptors can be imaged in rat hippocampus. The heterogeneous brain distribution of P-gp appeared to invalidate the use of cerebellum as a nonspecific reference region for SRTM modeling. Regional quantitation of P-gp may be necessary for accurate PET assessment of 5-HT(1A) receptor density when based on tracer uptake sensitive to P-gp modulation.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Ciclosporina/farmacología , Piperazinas/farmacocinética , Piridinas/farmacocinética , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/agonistas , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/antagonistas & inhibidores , Animales , Encéfalo/diagnóstico por imagen , Cuerpo Estriado/diagnóstico por imagen , Cuerpo Estriado/efectos de los fármacos , Cuerpo Estriado/metabolismo , Ciclosporina/metabolismo , Hipocampo/diagnóstico por imagen , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Técnicas In Vitro , Masculino , Tomografía de Emisión de Positrones , Ratas , Receptor de Serotonina 5-HT1A/metabolismo , Distribución TisularRESUMEN
OBJECT: Deep brain stimulation (DBS) has become an effective therapy for an increasing number of brain disorders. Recently demonstrated DBS of the posterior hypothalamus as a safe treatment for chronic intractable cluster headaches has drawn attention to this target, which is involved in the regulation of diverse autonomic functions and feeding behavior through complex integrative mechanisms. In this study, the authors assessed the feasibility of ventromedial hypothalamus (VMH) DBS in freely moving vervet monkeys to modulate food intake as a model for the potential treatment of eating disorders. METHODS: Deep brain stimulation electrodes were bilaterally implanted into the VMH of 2 adult male vervet monkeys by using the stereotactic techniques utilized in DBS in humans. Stimulators were implanted subcutaneously on the upper back, allowing ready access to program stimulation parameters while the animal remained conscious and freely moving. In anesthetized animals, intraoperatively and 6-10 weeks postsurgery, VMH DBS parameters were selected according to minimal cardiovascular and autonomic nervous system responses. Thereafter, conscious animals were subjected to 2 cycles of VMH DBS for periods of 8 and 3 days, and food intake and behavior were monitored. Animals were then killed for histological verification of probe placement. RESULTS: During VMH DBS, total food consumption increased. The 3-month bilateral implant of electrodes and subsequent periods of high-frequency VMH stimulation did not result in significant adverse behavioral effects. CONCLUSIONS: This is the first study in which techniques of hypothalamic DBS in humans have been applied in freely moving nonhuman primates. Future studies can now be conducted to determine whether VMH DBS can change hypothalamic responsivity to endocrine signals associated with adiposity for long-term modulation of food intake.
Asunto(s)
Estimulación Encefálica Profunda/métodos , Ingestión de Alimentos/fisiología , Hipotálamo Medio/fisiología , Animales , Presión Sanguínea/fisiología , Chlorocebus aethiops , Estimulación Encefálica Profunda/instrumentación , Electrodos Implantados , Estudios de Factibilidad , Conducta Alimentaria/fisiología , Proteína Ácida Fibrilar de la Glía/análisis , Frecuencia Cardíaca/fisiología , Masculino , Modelos Animales , Técnicas Estereotáxicas , Núcleo Hipotalámico Ventromedial/fisiologíaRESUMEN
The molecular mechanisms underlying the changes in the nigrostriatal pathway in Parkinson's disease (PD) are not completely understood. Here, we use mass spectrometry and microarrays to study the proteomic and transcriptomic changes in the striatum of two mouse models of PD, induced by the distinct neurotoxins 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and methamphetamine (METH). Proteomic analyses resulted in the identification and relative quantification of 912 proteins with two or more unique peptides and 86 proteins with significant abundance changes following neurotoxin treatment. Similarly, microarray analyses revealed 181 genes with significant changes in mRNA, following neurotoxin treatment. The combined protein and gene list provides a clearer picture of the potential mechanisms underlying neurodegeneration observed in PD. Functional analysis of this combined list revealed a number of significant categories, including mitochondrial dysfunction, oxidative stress response, and apoptosis. These results constitute one of the largest descriptive data sets integrating protein and transcript changes for these neurotoxin models with many similar end point phenotypes but distinct mechanisms.
Asunto(s)
Apoptosis/fisiología , Perfilación de la Expresión Génica , Mitocondrias/patología , Neostriado/metabolismo , Estrés Oxidativo/fisiología , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/patología , Proteómica , Animales , Apoptosis/genética , Modelos Animales de Enfermedad , Dopamina/deficiencia , Masculino , Ratones , Ratones Endogámicos C57BL , Mitocondrias/genética , Mitocondrias/metabolismo , Neostriado/efectos de los fármacos , Neostriado/patología , Neurotoxinas/farmacología , Estrés Oxidativo/genética , Enfermedad de Parkinson/genética , Proteoma/genética , Proteoma/metabolismo , ARN/metabolismoRESUMEN
Methamphetamine (METH)-associated alterations in the human striatal dopamine (DA) system have been identified with positron emission tomography (PET) imaging and post-mortem studies but have not been well correlated with behavioral changes or cumulative METH intake. Animal studies that model some aspects of human long-term METH abuse can establish dose-dependency profiles of both behavioral changes and potential brain neurotoxicities for identifying consequences of particular cumulative exposures. Based on parameters from human and our monkey pharmacokinetic studies, we modeled a prevalent human METH exposure of daily multiple doses in socially housed vervet monkeys. METH doses were escalated over 33 weeks, with final dosages resulting in estimated peak plasma METH concentrations of 1-3 microM, a range measured in human abusers. With larger METH doses, progressive increases in abnormal behavior and decreases in social behavior were observed on 'injection' days. Anxiety increased on 'no injection' days while aggression decreased throughout the study. Thereafter, during 3 weeks abstinence, differences in baseline vs post-METH behaviors were not observed. Post-mortem analysis of METH brains showed 20% lower striatal DA content while autoradiography studies of precommissural striatum showed 35% lower [3H]WIN35428 binding to the DA transporter. No statistically significant changes were detected for [3H]dihydrotetrabenazine binding to the vesicular monoamine transporter (METH-lower by 10%) or for [3H]SCH 23390 and [3H]raclopride binding to DA D1 and D2 receptors, respectively. Collectively, this long-term, escalating dose METH exposure modeling a human abuse pattern, not associated with high-dose binges, resulted in dose-dependent behavioral effects and caused persistent changes in presynaptic striatal DA system integrity.
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Conducta Animal/efectos de los fármacos , Estimulantes del Sistema Nervioso Central/administración & dosificación , Metanfetamina/administración & dosificación , Síndromes de Neurotoxicidad , Análisis de Varianza , Animales , Autorradiografía , Benzazepinas/farmacocinética , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/patología , Química Encefálica/efectos de los fármacos , Estimulantes del Sistema Nervioso Central/sangre , Chlorocebus aethiops , Cocaína/análogos & derivados , Cocaína/farmacocinética , Modelos Animales de Enfermedad , Antagonistas de Dopamina/farmacocinética , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/metabolismo , Inhibidores de Captación de Dopamina/farmacocinética , Relación Dosis-Respuesta a Droga , Masculino , Metanfetamina/sangre , Síndromes de Neurotoxicidad/metabolismo , Síndromes de Neurotoxicidad/patología , Síndromes de Neurotoxicidad/fisiopatología , Unión Proteica/efectos de los fármacos , Racloprida/farmacocinética , Conducta Social , Tritio/farmacocinéticaRESUMEN
Increases in basal ganglia iron are well documented for neurodegenerative diseases but have not been associated with methamphetamine (METH). In this study, vervet monkeys that received two doses of METH (2 mg/kg, intramuscularly, 6 h apart) showed at 1 month, iron increases in substantia nigra pars reticulata and globus pallidus, with concurrent increases of ferritin-immunoreactivity and decreases of tyrosine hydroxylase-immunoreactivity in substantia nigra. At 1.5 years, substantia nigra tyrosine hydroxylase-immunoreactivity had recovered while iron and ferritin-immunoreactivity increases persisted. Globus pallidus and substantia nigra iron levels of the adult METH-exposed animals (age 5-9 years) were now comparable with those of drug-naive, aged animals (19-22 years), suggesting an aging-related condition that might render those regions more vulnerable to oxidative stress.
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Envejecimiento/metabolismo , Enfermedades de los Ganglios Basales/inducido químicamente , Ganglios Basales/efectos de los fármacos , Trastornos del Metabolismo del Hierro/inducido químicamente , Hierro/metabolismo , Metanfetamina/toxicidad , Envejecimiento/patología , Animales , Ganglios Basales/metabolismo , Ganglios Basales/patología , Enfermedades de los Ganglios Basales/metabolismo , Enfermedades de los Ganglios Basales/fisiopatología , Estimulantes del Sistema Nervioso Central/toxicidad , Chlorocebus aethiops , Modelos Animales de Enfermedad , Dopamina/metabolismo , Ferritinas/efectos de los fármacos , Ferritinas/metabolismo , Globo Pálido/efectos de los fármacos , Globo Pálido/metabolismo , Globo Pálido/patología , Trastornos del Metabolismo del Hierro/metabolismo , Trastornos del Metabolismo del Hierro/fisiopatología , Masculino , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/fisiología , Especificidad de la Especie , Sustancia Negra/efectos de los fármacos , Sustancia Negra/metabolismo , Sustancia Negra/patología , Tirosina 3-Monooxigenasa/efectos de los fármacos , Tirosina 3-Monooxigenasa/metabolismoRESUMEN
Characterization of methamphetamine's (METH) dose-dependent effects on brain neurochemistry may represent a critical component for better understanding the range of resultant behavioral pathologies. Most human studies, however, have assessed only the effects of long term, high dose METH abuse (e.g., greater than 1000 mg/day) in individuals meeting DSM-IV criteria for METH dependence. Yet, for the majority of METH abusers, their patterns of METH exposure that consist of lower doses remain less well-characterized. In this study, blood samples were obtained from 105 individuals detained by police for possible criminal activity and testing positive for stimulants by EMIT assay. METH blood concentrations were subsequently quantified by GC-MS and were predominantly in the low micromolar range (0.1-11.1 microM), with median and mean values of 1.3 microM (0.19 mg/l) and 2 microM (0.3 mg/l), respectively. Pharmacokinetic calculations based on these measured values were used to estimate initial METH body burdens, the median value being 52 mg. Modeling a 52 mg dose for a 4 day-METH maintenance exposure pattern of 4 doses/day at 4 h intervals showed that blood concentrations remained between 1 and 4 microM during this period. Collectively, these data present evidence for a METH exposure pattern distinct from high dose-METH abuse and provide the rationale for assessing potential brain pathology associated with such lower dose-METH exposure.
Asunto(s)
Estimulantes del Sistema Nervioso Central/sangre , Estimulantes del Sistema Nervioso Central/farmacocinética , Metanfetamina/sangre , Metanfetamina/farmacocinética , Trastornos Relacionados con Sustancias/sangre , Anfetamina/sangre , Anfetamina/farmacocinética , Relación Dosis-Respuesta a Droga , Medicina Legal , Humanos , Factores de TiempoRESUMEN
A major feature of human methamphetamine (METH) abuse is the gradual dose escalation that precedes high-dose exposure. The period of escalating doses (EDs) is likely associated with development of tolerance to aspects of METH's pharmacologic and toxic effects but the relative contributions of pharmacokinetic and pharmacodynamic factors have not been well defined. In our prior studies in rats, we showed that pretreatment with an ED-METH regimen (0.1-4.0 mg/kg over 14 days) attenuated the toxicity of a subsequently administered high-dose METH binge (4 x 6 mg/kg at 2 h interval) that itself produced behavioral stereotypy, increases in core temperature, and decreases in DA system phenotypic markers in caudate-putamen (CP). Using those ED-METH and binge protocols in the present studies, pharmacokinetic and pharmacodynamic parameters that may have contributed to the apparent neuroprotection afforded by ED-METH were assessed. The ED-METH regimen itself reduced [(3)H]WIN35,428 (WIN) binding to the dopamine transporter (DAT) by 15% in CP, but did not affect DA content. During the METH binge, ED-METH pretreated animals showed attenuated increases in core temperature while concurrent microdialysis studies in CP showed a reduced DA response despite unaltered extracellular levels of METH. At 1 h after the binge, concentrations of METH and its metabolite amphetamine in brain and plasma were unaffected by the ED-METH. The results show that ED-METH pretreatment produces reductions in DAT binding and the DA response during a subsequent METH binge by altering pharmacodynamic and not pharmacokinetic parameters.
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Trastornos Relacionados con Anfetaminas/metabolismo , Trastornos Relacionados con Anfetaminas/psicología , Estimulantes del Sistema Nervioso Central/farmacología , Estimulantes del Sistema Nervioso Central/farmacocinética , Metanfetamina/farmacología , Metanfetamina/farmacocinética , Ácido 3,4-Dihidroxifenilacético/metabolismo , Anfetamina/metabolismo , Trastornos Relacionados con Anfetaminas/patología , Animales , Temperatura Corporal/efectos de los fármacos , Estimulantes del Sistema Nervioso Central/administración & dosificación , Cromatografía Líquida de Alta Presión , Cocaína/análogos & derivados , Cocaína/metabolismo , Inhibidores de Captación de Dopamina/metabolismo , Cromatografía de Gases y Espectrometría de Masas , Ácido Homovanílico/metabolismo , Masculino , Metanfetamina/administración & dosificación , Microdiálisis , Neostriado/metabolismo , Neostriado/patología , Ratas , Ratas Sprague-DawleyRESUMEN
Increased abundance of nitrotyrosine modifications of proteins have been documented in multiple pathologies in a variety of tissue types and play a role in the redox regulation of normal metabolism. To identify proteins sensitive to nitrating conditions in vivo, a comprehensive proteomic data set identifying 7792 proteins from a whole mouse brain, generated by LC/LC-MS/MS analyses, was used to identify nitrated proteins. This analysis resulted in the identification of 31 unique nitrotyrosine sites within 29 different proteins. More than half of the nitrated proteins that have been identified are involved in Parkinson's disease, Alzheimer's disease, or other neurodegenerative disorders. Similarly, nitrotyrosine immunoblots of whole brain homogenates show that treatment of mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), an experimental model of Parkinson's disease, induces an increased level of nitration of the same protein bands observed to be nitrated in brains of untreated animals. Comparing sequences and available high-resolution structures around nitrated tyrosines with those of unmodified sites indicates a preference of nitration in vivo for surface accessible tyrosines in loops, a characteristic consistent with peroxynitrite-induced tyrosine modification. In addition, most sequences contain cysteines or methionines proximal to nitrotyrosines, contrary to suggestions that these amino acid side chains prevent tyrosine nitration. More striking is the presence of a positively charged moiety near the sites of nitration, which is not observed for non-nitrated tyrosines. Together, these observations suggest a predictive tool of functionally important sites of nitration and that cellular nitrating conditions play a role in neurodegenerative changes in the brain.
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Encéfalo/metabolismo , Proteínas del Tejido Nervioso/química , Proteínas del Tejido Nervioso/metabolismo , Enfermedades Neurodegenerativas/metabolismo , 1-Metil-4-fenil-1,2,3,6-Tetrahidropiridina , Secuencia de Aminoácidos , Animales , Acción Capilar , Cromatografía Liquida , Espectrometría de Masas , Ratones , Ratones Endogámicos C57BL , Modelos Moleculares , Datos de Secuencia Molecular , Nitratos/metabolismo , Fragmentos de Péptidos , Conformación Proteica , ProteomaRESUMEN
OBJECT: The purpose of this work was to investigate the targeting and dosimetric characteristics of a linear accelerator (LINAC) system dedicated for stereotactic radiosurgery compared with those of a commercial gamma knife (GK) unit. METHODS: A phantom was rigidly affixed within a Leksell stereotactic frame and axial computerized tomography scans were obtained using an appropriate stereotactic localization device. Treatment plans were performed, film was inserted into a recessed area, and the phantom was positioned and treated according to each treatment plan. In the case of the LINAC system, four 140 degrees arcs, spanning +/-60 degrees of couch rotation, were used. In the case of the GK unit, all 201 sources were left unplugged. Radiation was delivered using 3- and 8-mm LINAC collimators and 4- and 8-mm collimators of the GK unit. Targeting ability was investigated independently on the dedicated LINAC by using a primate model. Measured 50% spot widths for multisource, single-shot radiation exceeded nominal values in all cases by 38 to 70% for the GK unit and 11 to 33% for the LINAC system. Measured offsets were indicative of submillimeter targeting precision on both devices. In primate studies, the appearance of an magnetic resonance imaging-enhancing lesion coincided with the intended target. CONCLUSIONS: Radiosurgery performed using the 3-mm collimator of the dedicated LINAC exhibited characteristics that compared favorably with those of a dedicated GK unit. Overall targeting accuracy in the submillimeter range can be achieved, and dose distributions with sharp falloff can be expected for both devices.
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Radiocirugia/normas , Radioterapia Conformacional/normas , Dosimetría por Película , Humanos , Fantasmas de Imagen , Dosificación Radioterapéutica , Radioterapia Conformacional/instrumentación , Tomografía Computarizada por Rayos XRESUMEN
An automated method for placement of 3D rat brain atlas-derived volumes of interest (VOIs) onto PET studies has been designed and evaluated. VOIs representing major structures of the rat brain were defined on a set of digitized cryosectioned images of the rat brain. For VOI placement, each PET study was registered with a synthetic PET target constructed from the VOI template. Registration was accomplished with an automated algorithm that maximized the mutual information content of the image volumes. The accuracy and precision of this method for VOI placement was determined using datasets from PET studies of the striatal dopamine and hippocampal serotonin systems. Each evaluated PET study could be registered to at least one synthetic PET target without obvious failure. Registration was critically dependent upon the initial position of the PET study relative to the synthetic PET target, but not dependent on the amount of synthetic PET target smoothing. An evaluation algorithm showed that resultant radioactivity concentration measurements of selected brain structures had errors=2% due to misalignment with the corresponding VOI. Further, radioligand binding values calculated from these measurements were found to be more precise than those calculated from measurements obtained with manually drawn regions of interest (ROIs). Overall, evaluation results demonstrated that this atlas-derived VOI method can be used to obtain unbiased measurements of radioactivity concentration from PET studies. Its automated features, and applicability to different radioligands and brain regions, will facilitate quantitative rat brain PET assessment procedures.
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Mapeo Encefálico/métodos , Encéfalo/anatomía & histología , Encéfalo/diagnóstico por imagen , Interpretación de Imagen Asistida por Computador/métodos , Tomografía Computarizada de Emisión/normas , Animales , Atlas como Asunto , Automatización , Cerebelo/diagnóstico por imagen , Cerebelo/fisiología , Corteza Cerebral/diagnóstico por imagen , Corteza Cerebral/fisiología , Dopamina/fisiología , Hipocampo/diagnóstico por imagen , Hipocampo/fisiología , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Neostriado/diagnóstico por imagen , Neostriado/fisiología , Ratas , Ratas Sprague-Dawley , Serotonina/fisiología , Tálamo/diagnóstico por imagen , Tálamo/fisiología , Tomografía Computarizada de Emisión de Fotón ÚnicoRESUMEN
To facilitate high-throughput 3D imaging of brain gene expression, a new method called voxelation has been developed. Spatially registered voxels (cubes) are analyzed, resulting in multiple volumetric maps of gene expression analogous to the images reconstructed in biomedical imaging systems. Using microarrays, 40 voxel images for 9000 genes were acquired from brains of both normal mice and mice in which a pharmacological model of Parkinson's disease (PD) had been induced by methamphetamine. Quality-control analyses established the reproducibility of the voxelation procedure. The investigation revealed a common network of coregulated genes shared between the normal and PD brain, and allowed identification of putative control regions responsible for these networks. In addition, genes involved in cell/cell interactions were found to be prominently regulated in the PD brains. Finally, singular value decomposition (SVD), a mathematical method used to provide parsimonious explanations of complex data sets, identified gene vectors and their corresponding images that distinguished between normal and PD brain structures, most pertinently the striatum.