RESUMEN
PURPOSE: We propose and evaluate multiphoton parallel transmission (MP-pTx) to mitigate flip angle inhomogeneities in high-field MRI. MP-pTx is an excitation method that utilizes a single, conventional birdcage coil supplemented with low-frequency (kHz) irradiation from a multichannel shim array and/or gradient channels. SAR analysis is simplified to that of a conventional birdcage coil, because only the radiofrequency (RF) field from the birdcage coil produces significant SAR. METHODS: MP-pTx employs an off-resonance RF pulse from a conventional birdcage coil supplemented with oscillating z $$ z $$ -directed fields from a multichannel shim array and/or the gradient coils. We simulate the ability of MP-pTx to create uniform nonselective brain excitations at 7 T using realistic B 1 + $$ {\mathrm{B}}_1^{+} $$ and Δ B 0 $$ \Delta {\mathrm{B}}_0 $$ field maps. The RF, shim array, and gradient waveform's amplitudes and phases are optimized using a genetic algorithm followed by sequential quadratic programming. RESULTS: A 1 ms MP-pTx excitation using a 32-channel shim array with current constrained to less than 50 Amp-turns reduced the transverse magnetization's normalized root-mean-squared error from 29% for a conventional birdcage excitation to 6.6% and was nearly 40% better than a 1 ms birdcage coil 5 kT-point excitation with optimized kT-point locations and comparable pulse power. CONCLUSION: The MP-pTx method resembles conventional pTx in its goals and approach but replaces the parallel RF channels with cheaper, low-frequency shim channels. The method mitigates high-field flip angle inhomogeneities to a level better than 3 T CP-mode and comparable to 7 T pTx while retaining the straightforward SAR characteristics of conventional birdcage excitations, as low-frequency shim array fields produce negligible SAR.
Asunto(s)
Algoritmos , Encéfalo , Imagen por Resonancia Magnética , Imagen por Resonancia Magnética/instrumentación , Imagen por Resonancia Magnética/métodos , Humanos , Encéfalo/diagnóstico por imagen , Reproducibilidad de los Resultados , Fantasmas de Imagen , Simulación por Computador , Fotones , Aumento de la Imagen/métodos , Procesamiento de Señales Asistido por Computador , Interpretación de Imagen Asistida por Computador/métodosRESUMEN
Objective.Non-invasive functional brain imaging modalities are limited in number, each with its own complex trade-offs between sensitivity, spatial and temporal resolution, and the directness with which the measured signals reflect neuronal activation. Magnetic particle imaging (MPI) directly maps the cerebral blood volume (CBV), and its high sensitivity derives from the nonlinear magnetization of the superparamagnetic iron oxide nanoparticle (SPION) tracer confined to the blood pool. Our work evaluates functional MPI (fMPI) as a new hemodynamic functional imaging modality by mapping the CBV response in a rodent model where CBV is modulated by hypercapnic breathing manipulation.Approach.The rodent fMPI time-series data were acquired with a mechanically rotating field-free line MPI scanner capable of 5 s temporal resolution and 3 mm spatial resolution. The rat's CBV was modulated for 30 min with alternating 5 min hyper-/hypocapnic states, and processed using conventional fMRI tools. We compare our results to fMRI responses undergoing similar hypercapnia protocols found in the literature, and reinforce this comparison in a study of one rat with 9.4T BOLD fMRI using the identical protocol.Main results.The initial image in the time-series showed mean resting brain voxel SNR values, averaged across rats, of 99.9 following the first 10 mg kg-1SPION injection and 134 following the second. The time-series fit a conventional General Linear Model with a 15%-40% CBV change and a peak pixel CNR between 12 and 29, 2-6× higher than found in fMRI.Significance.This work introduces a functional modality with high sensitivity, although currently limited spatial and temporal resolution. With future clinical-scale development, a large increase in sensitivity could supplement other modalities and help transition functional brain imaging from a neuroscience tool focusing on population averages to a clinically relevant modality capable of detecting differences in individual patients.
Asunto(s)
Circulación Cerebrovascular , Hipercapnia , Ratas , Animales , Hipercapnia/diagnóstico por imagen , Circulación Cerebrovascular/fisiología , Encéfalo/irrigación sanguínea , Imagen por Resonancia Magnética/métodos , Fenómenos Magnéticos , Mapeo EncefálicoRESUMEN
Pharmacokinetic limitations associated with oral ivermectin may limit its success as a potential COVID-19 treatment based on in vitro experiments which demonstrate antiviral efficacy against SARS-CoV-2 at high concentrations. Targeted delivery to the lungs is a practical way to overcome these limitations and ensure the presence of a therapeutic concentration of the drug in a clinically critical site of viral pathology. In this study, the pharmacokinetics (PK) and safety of inhaled dry powders of ivermectin with lactose were investigated in healthy mice. Female BALB/c mice received ivermectin formulation by intratracheal administration at high (3.15 mg/kg) or low doses (2.04 mg/kg). Plasma, bronchoalveolar lavage fluid (BALF), lung, kidney, liver, and spleen were collected at predetermined time points up to 48 h and analyzed for PK. Histological evaluation of lungs was used to examine the safety of the formulation. Inhalation delivery of ivermectin formulation showed improved pharmacokinetic performance as it avoided protein binding encountered in systemic delivery and maintained a high exposure above the in vitro antiviral concentration in the respiratory tract for at least 24 h. The local toxicity was mild with less than 20% of the lung showing histological damage at 24 h, which resolved to 10% by 48 h.
Asunto(s)
Tratamiento Farmacológico de COVID-19 , Administración por Inhalación , Animales , Antivirales , Inhaladores de Polvo Seco , Femenino , Humanos , Ivermectina , Pulmón/metabolismo , Ratones , Ratones Endogámicos BALB C , Polvos/metabolismo , SARS-CoV-2RESUMEN
Background: Ivermectin has received worldwide attention as a potential COVID-19 treatment after showing antiviral activity against SARS-CoV-2 in vitro. However, the pharmacokinetic limitations associated with oral administration have been postulated as limiting factors to its bioavailability and efficacy. These limitations can be overcome by targeted delivery to the lungs. In this study, inhalable dry powders of ivermectin and lactose crystals were prepared and characterized for the potential treatment of COVID-19. Methods: Ivermectin was co-spray dried with lactose monohydrate crystals and conditioned by storage at two different relative humidity points (43% and 58% RH) for a week. The in vitro dispersion performance of the stored powders was examined using a medium-high resistance Osmohaler connecting to a next-generation impactor at 60 L/min flow rate. The solid-state characteristics including particle size distribution and morphology, crystallinity, and moisture sorption profiles of raw and spray-dried ivermectin samples were assessed by laser diffraction, scanning electron microscopy, Raman spectroscopy, X-ray powder diffraction, thermogravimetric analysis, differential scanning calorimetry, and dynamic vapor sorption. Results: All the freshly spray-dried formulation (T0) and the conditioned samples could achieve the anticipated therapeutic dose with fine particle dose of 300 µg, FPFrecovered of 70%, and FPFemitted of 83%. In addition, the formulations showed a similar volume median diameter of 4.3 µm and span of 1.9. The spray-dried formulations were stable even after conditioning and exposing to different RH points as ivermectin remained amorphous with predominantly crystalline lactose. Conclusion: An inhalable and stable dry powder of ivermectin and lactose crystals was successfully formulated. This powder inhaler ivermectin candidate therapy appears to be able to deliver doses that could be safe and effective to treat the SARS-COV-2 infection. Further development of this therapy is warranted.
Asunto(s)
Tratamiento Farmacológico de COVID-19 , Administración por Inhalación , Antivirales , Inhaladores de Polvo Seco , Humanos , Ivermectina , Lactosa , Tamaño de la Partícula , Polvos/química , Aerosoles y Gotitas Respiratorias , SARS-CoV-2RESUMEN
The preservation of the posterior cruciate ligament in cruciate retaining (CR) total knee arthroplasty (TKA) designs has the potential to restore healthy knee biomechanics; however, concerns related to kinematic asymmetries during functional activities still exist in unilateral TKA patients. As there is a limited data available regarding the ability of the contemporary CR TKA design with concave medial and convex lateral tibial polyethylene bearing components to restore healthy knee biomechanics, this study aimed to investigate in vivo three-dimensional knee kinematics in CR TKA patients during strenuous knee flexion activities and gait. Using a combined computer tomography and dual fluoroscopic imaging system approach, in vivo kinematics of 15 unilateral CR TKA patients (comparison of replaced and contralateral nonreplaced knee) were evaluated during sit-to-stand, step-ups, single-leg deep lunge, and level walking. The patient cohort was followed-up at an average of 24.5 months ( ± 12.6, range 13-42) from surgical procedure. Significantly smaller internal knee rotation angles were observed for the contemporary CR TKA design during step-ups (2.6 ± 5.8 vs. 6.3 ± 6.6 degrees, p < 0.05) and gait (0.6 ± 4.6 vs. 6.3 ± 6.8 degrees, p < 0.05). Significantly larger proximal and anterior femoral translations were measured during sit-to-stand (34.7 ± 4.5 vs. 29.9 ± 3.1 mm, p < 0.05; -2.5 ± 2.9 vs. -8.1 ± 4.4 mm, p < 0.05) and step-ups (34.1 ± 4.5 vs. 30.8 ± 2.9 mm, p < 0.05; 2.2 ± 3.2 vs. -3.5 ± 4.5 mm, p < 0.05). Significantly smaller ranges of varus/valgus and internal/external rotation range of motion were observed for CR TKA, when compared with the nonoperated nee, during strenuous activities and gait. The preservation of the posterior cruciate ligament in the contemporary asymmetric bearing geometry CR TKA design with concave medial and convex lateral tibial polyethylene bearing components has the potential to restore healthy knee biomechanics; however, the study findings demonstrate that native knee kinematics were not fully restored in patients with unilateral asymmetric tibial polyethylene bearing geometry CR TKA during functional activities.
Asunto(s)
Artroplastia de Reemplazo de Rodilla , Prótesis de la Rodilla , Artroplastia de Reemplazo de Rodilla/métodos , Fenómenos Biomecánicos , Marcha , Humanos , Articulación de la Rodilla/cirugía , Polietileno , Rango del Movimiento ArticularRESUMEN
PURPOSE: A new CR TKA design with concave medial and convex lateral tibial polyethylene bearing components was introduced recently to improve functional outcomes. This study aimed to investigate in-vivo articular contact kinematics in unilateral asymmetrical tibial polyethylene geometry CR TKA patients during strenuous knee flexion activities. METHODS: Fifteen unilateral CR TKA patients (68.4 ± 5.8 years; 6 male/9 female) were evaluated for both knees during sit-to-stand, single-leg deep lunges and step-ups using validated combined computer tomography and dual fluoroscopic imaging system. Medial and lateral condylar contact positions were quantified during weight-bearing flexion activities. The Wilcoxon signed-rank test was performed to determine if there is a significant difference in articular contact kinematics during strenuous flexion activities between CR TKA and the non-operated knees. RESULTS: Contact excursions of the lateral condyle in CR TKAs were significantly more anteriorly located than the contralateral non-operated knee during sit-to-stand (3.7 ± 4.8 mm vs - 7.8 ± 4.3 mm) and step-ups (- 1.5 ± 3.2 mm vs - 6.3 ± 5.8 mm). Contact excursions of the lateral condyle in CR TKAs were significantly less laterally located than the contralateral non-operated knee during sit-to-stand (21.4 ± 2.8 mm vs 24.5 ± 4.7 mm) and single-leg deep lunges (22.6 ± 4.4 mm vs 26.2 ± 5.7 mm, p < 0.05). Lateral condyle posterior rollback was not fully restored in CR TKA patients during sit-to-stand (9.8 ± 6.7 mm vs 12.9 ± 8.3 mm) and step-ups (8.1 ± 4.8 mm vs 12.2 ± 6.4 mm). Lateral pivoting patterns were observed in 80%, 73% and 69% of patients during sit-to-stand, step-ups and single-leg deep lunges respectively. CONCLUSION: Although lateral femoral rollback and lateral pivoting patterns were observed during strenuous functional daily activities, asymmetric contact kinematics still persisted in unilateral CR TKA patients. This suggests the specific investigated contemporary asymmetrical tibial polyethylene geometry CR TKA design evaluated in this study does not fully replicate healthy knee contact kinematics during strenuous functional daily activities. LEVEL OF EVIDENCE: III.
Asunto(s)
Artroplastia de Reemplazo de Rodilla , Prótesis de la Rodilla , Artroplastia de Reemplazo de Rodilla/métodos , Fenómenos Biomecánicos , Femenino , Humanos , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/cirugía , Masculino , Polietileno , Rango del Movimiento Articular , Tibia/cirugíaRESUMEN
Fronto-temporal dementia (FTD) associated with Fused in Sarcoma (FUS) protein accumulation is an uncommon cause of FTD with a distinct syndrome of young age onset behavioral variant FTD, without a family history of FTD and caudate atrophy. We present a sporadic case of a 61-year-old patient with mixed features of both behavioral variant FTD with later semantic language dissolution associated with pathologically proven FUS. He was older than usual for FUS pathology, his course was rapidly progressive, and he had atypical language features. This case broadens the clinical spectrum caused by FUS-protein-related FTD.
Asunto(s)
Núcleo Caudado/patología , Demencia Frontotemporal/patología , Demencia Frontotemporal/fisiopatología , Proteína FUS de Unión a ARN/metabolismo , Lóbulo Temporal/patología , Edad de Inicio , Atrofia/patología , Progresión de la Enfermedad , Resultado Fatal , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Proteína FUS de Unión a ARN/genéticaRESUMEN
D1-dopamine receptors (Drd1a) are highly expressed in the deep layers of the cerebral cortex and the striatum. A number of human diseases such as Huntington disease and schizophrenia are known to have cortical pathology involving dopamine receptor expressing neurons. To illuminate their functional role, we exploited a Cre/Lox molecular paradigm to generate Emx-1(tox) MUT mice, a transgenic line in which cortical Drd1a-expressing pyramidal neurons were selectively ablated. Emx-1(tox) MUT mice displayed prominent forelimb dystonia, hyperkinesia, ataxia on rotarod testing, heightened anxiety-like behavior, and age-dependent abnormalities in a test of social interaction. The latter occurred in the context of normal working memory on testing in the Y-maze and for novel object recognition. Some motor and behavioral abnormalities in Emx-1(tox) MUT mice overlapped with those in CamKIIα(tox) MUT transgenic mice, a line in which both striatal and cortical Drd1a-expressing cells were ablated. Although Emx-1(tox) MUT mice had normal striatal anatomy, both Emx-1(tox) MUT and CamKIIα(tox) MUT mice displayed selective neuronal loss in cortical layers V and VI. This study shows that loss of cortical Drd1a-expressing cells is sufficient to produce deficits in multiple motor and behavioral domains, independent of striatal mechanisms. Primary cortical changes in the D1 dopamine receptor compartment are therefore likely to model a number of core clinical features in disorders such as Huntington disease and schizophrenia.
Asunto(s)
Conducta Animal/fisiología , Corteza Cerebral/fisiología , Enfermedad de Huntington/fisiopatología , Células Piramidales/fisiología , Receptores de Dopamina D1/fisiología , Esquizofrenia/fisiopatología , Animales , Ansiedad/genética , Ansiedad/fisiopatología , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/genética , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/fisiología , Femenino , Marcha/genética , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/fisiología , Enfermedad de Huntington/genética , Masculino , Memoria/fisiología , Ratones , Ratones Transgénicos , Actividad Motora/genética , Mutación , Fenotipo , Receptores de Dopamina D1/genética , Esquizofrenia/genética , Conducta Social , Factores de Transcripción/genética , Factores de Transcripción/fisiologíaRESUMEN
Prenatal nicotine exposure alters breathing and ventilatory responses to stress through stimulation of nicotine acetylcholine receptors (nAChRs). We tested the hypothesis that α4-containing nAChRs are involved in mediating the effects of prenatal nicotine exposure on ventilatory and metabolic responses to intermittent mild asphyxia (MA). Using open-flow plethysmography, we measured ventilation (VÌ(E)) and rate of O2 consumption ( VÌ(O2)) of wild-type (WT) and α4-knock-out (KO) mice, at postnatal (P) days 1-2 and 7-8, with and without prenatal nicotine exposure (6 mg kg(-1) day(-1) beginning on embryonic day 14). Mice were exposed to seven 2 min cycles of mild asphyxia (10% O2 and 5% CO2), each interspersed with 2 min of air. Compared to WT, α4 KO mice had increased air VÌ(E) and VÌ(O2) at P7-8, but not P1-2. Irrespective of age, genotype had no effect on the hyperventilatory response (increase in VÌ(E)/VÌ(O2)) to MA. At P1-2, nicotine suppressed air VÌ(E) and VÌ(O2) in both genotypes but did not affect the hyperventilatory response to MA. At P7-8 nicotine suppressed air VÌ(E) and VÌ(O2) of only α4 KO's but also significantly enhanced VÌ(E) during MA (nearly double that of WT; p<0.001). This study has revealed complex effects of α4 nAChR deficiency and prenatal nicotine exposure on ventilatory and metabolic interactions and responses to stress.
Asunto(s)
Asfixia Neonatal/fisiopatología , Hiperventilación/inducido químicamente , Hiperventilación/genética , Efectos Tardíos de la Exposición Prenatal/genética , Efectos Tardíos de la Exposición Prenatal/fisiopatología , Receptores Nicotínicos/deficiencia , Factores de Edad , Análisis de Varianza , Animales , Animales Recién Nacidos , Femenino , Recién Nacido de Bajo Peso/fisiología , Masculino , Ratones , Ratones Noqueados , Consumo de Oxígeno/efectos de los fármacos , Consumo de Oxígeno/genética , Embarazo , Receptores Nicotínicos/genética , Respiración/efectos de los fármacos , Respiración/genética , Volumen de Ventilación Pulmonar/efectos de los fármacos , Volumen de Ventilación Pulmonar/genética , Factores de TiempoRESUMEN
Tobacco smoking is a major cause of death and disease and as such there is a critical need for the development of new therapeutic approaches to treat nicotine addiction. Here, we utilize genetic and pharmacological tools to further investigate the nicotinic acetylcholine receptor (nAChR) subtypes that support intravenous self-administration of nicotine. α4-S248F mice contain a point mutation within the α4 nAChR subunit which confers increased sensitivity to nicotine and resistance to mecamylamine. Here, we show that acute administration of mecamylamine (2 mg/kg, i.p.) reduces established nicotine self-administration (0.05 mg/kg/infusion) in wild-type (WT), but not in α4-S248F heterozygous mice, demonstrating a role for α4* nAChRs in the modulation of ongoing nicotine self-administration. Administration of N,N-decane-1,10-diyl-bis-3-picolinium diiodide (bPiDI), a selective α6ß2* nAChR antagonist, dose dependently (5 and 10 mg/kg, i.p.) impairs the acquisition of nicotine self-administration and reduces established nicotine self-administration in WT mice when administered acutely (10 mg/kg, i.p.). This was not due to a general reduction in locomotor activity and the same dose of bPiDI did not affect operant responding for sucrose. bPiDI treatment (10 mg/kg, i.p.) also impaired both the acquisition and maintenance of nicotine self-administration in α4-S248F heterozygous mice. This provides further evidence for the involvement of α6ß2* nAChRs in the reinforcing effects of nicotine that underlies its ability to support ongoing self-administration. Taken together, selective targeting of α6ß2* or α4α6ß2* nAChRs may prove to be an effective strategy for the development of smoking cessation therapies.
Asunto(s)
Nicotina/farmacología , Agonistas Nicotínicos/farmacología , Receptores Nicotínicos/fisiología , Análisis de Varianza , Animales , Condicionamiento Operante , Relación Dosis-Respuesta a Droga , Masculino , Mecamilamina/farmacología , Ratones Transgénicos , Actividad Motora/efectos de los fármacos , Antagonistas Nicotínicos/farmacología , Picolinas/farmacología , Compuestos de Piridinio/farmacología , Autoadministración , Sacarosa/farmacología , Edulcorantes/farmacologíaRESUMEN
Progressive cell loss is observed in the striatum, cerebral cortex, thalamus, hypothalamus, subthalamic nucleus and hippocampus in Huntington disease. In the striatum, dopamine-responsive medium spiny neurons are preferentially lost. Clinical features include involuntary movements, gait and orofacial impairments in addition to cognitive deficits and psychosis, anxiety and mood disorders. We utilized the Cre-LoxP system to generate mutant mice with selective postnatal ablation of D1 dopamine receptor-expressing striatal neurons to determine which elements of the complex Huntington disease phenotype relate to loss of this neuronal subpopulation. Mutant mice had reduced body weight, locomotor slowing, reduced rearing, ataxia, a short stride length wide-based erratic gait, impairment in orofacial movements and displayed haloperidol-suppressible tic-like movements. The mutation was associated with an anxiolytic profile. Mutant mice had significant striatal-specific atrophy and astrogliosis. D1-expressing cell number was reduced throughout the rostrocaudal extent of the dorsal striatum consistent with partial destruction of the striatonigral pathway. Additional striatal changes included up-regulated D2 and enkephalin mRNA, and an increased density of D2 and preproenkephalin-expressing projection neurons, and striatal neuropeptide Y and cholinergic interneurons. These data suggest that striatal D1-cell-ablation alone may account for the involuntary movements and locomotor, balance and orofacial deficits seen not only in HD but also in HD phenocopy syndromes with striatal atrophy. Therapeutic strategies would therefore need to target striatal D1 cells to ameliorate deficits especially when the clinical presentation is dominated by a bradykinetic/ataxic phenotype with involuntary movements.
Asunto(s)
Cuerpo Estriado/metabolismo , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/fisiopatología , Receptores de Dopamina D1/metabolismo , Animales , Encéfalo/metabolismo , Encéfalo/patología , Recuento de Células , Cuerpo Estriado/patología , Discinesias/fisiopatología , Femenino , Marcha/fisiología , Masculino , Ratones , Ratones Endogámicos , Ratones Transgénicos , Equilibrio Postural/fisiología , Receptores de Dopamina D1/genéticaRESUMEN
BACKGROUND: Mice generated by a Cre/LoxP transgenic paradigm were used to model neurodegenerative basal ganglia disease of which Huntington disease (HD) is the prototypical example. In HD, death occurs in striatal projection neurons as well as cortical neurons. Cortical and striatal neurons that express the D1 dopamine receptor (Drd1a) degenerate in HD. The contribution that death of specific neuronal cell populations makes to the HD disease phenotype and the response of the brain to loss of defined cell subtypes is largely unknown. METHODS: Drd1a-expressing cells were targeted for cell death and three independent lines generated; a striatal-restricted line, a cortical-restricted line and a global line in which Drd1a cells were deleted from both the striatum and cortex. Two independent experimental approaches were used. In the first, the proliferative marker Ki-67 was used to identify proliferating cells in eighty-week-old mice belonging to a generic global line, a global in which Drd1a cells express green fluorescent protein (GFP-global) and in eighty-week-old mice of a cortical line. In the second experiment, the proliferative response of four-week-old mice belonging to GFP-global and striatal lines was assessed using the thymidine analogue BrdU. The phenotype of proliferating cells was ascertained by double staining for BrdU and Olig2 (an oligodendrocyte marker), Iba1 (a microglial cell marker), S100ß (an astroglial cell marker), or NeuN (a neuronal cell marker). RESULTS: In the first study, we found that Ki-67-expressing cells were restricted to the striatal side of the lateral ventricles. Control mice had a greater number of Ki-67+ cells than mutant mice. There was no overlap between Ki-67 and GFP staining in control or mutant mice, suggesting that cells did not undergo cell division once they acquired a Drd1a phenotype. In contrast, in the second study we found that BrdU+ cells were identified throughout the cortex, striatum and periventricular region of control and mutant mice. Mutant mice from the GFP-global line showed increased BrdU+ cells in the cortex, striatum and periventricular region relative to control. Striatal line mutant mice had an increased number of BrdU+ cells in the striatum and periventricular region, but not the cortex. The number of microglia, astrocytes, oligodendrocytes and neurons generated from dividing progenitors was increased relative to control mice in most brain regions in mutant mice from the GFP-global line. In contrast, striatal line mutant mice displayed an increase only in the number of dividing microglia in striatal and periventricular regions. CONCLUSIONS: Genetically programmed post-natal ablation of Drd1a-expressing neurons is associated with an extensive proliferative response involving multiple cell lineages. The nature of the tissue response has the potential not only to remove cellular debris but also to forge physiologically meaningful brain repair. Age related deficits in proliferation are seen in mutant lines. A blunted endogenous reparative response may underlie the cumulative deficits characteristic of age related neurodegeneration.
Asunto(s)
Enfermedad de Huntington/patología , Microglía/citología , Neurogénesis , Neuronas/citología , Animales , Enfermedades de los Ganglios Basales/patología , Recuento de Células , Linaje de la Célula , Proliferación Celular , Modelos Animales de Enfermedad , Antígeno Ki-67/análisis , Ratones , Ratones Transgénicos , Microscopía Fluorescente , Enfermedades Neurodegenerativas/patología , FenotipoRESUMEN
Considerable topographic overlap exists between brain opioidergic and dopaminergic neurons. Pharmacological blockade of the dopamine D(1) receptor (Drd1a) reverses several behavioural phenomena elicited by opioids. The present study examines the effects of morphine in adult mutant (MUT) mice expressing the attenuated diphtheria toxin-176 gene in Drd1a-expressing cells, a mutant line shown previously to undergo post-natal striatal atrophy and loss of Drd1a-expression. MUT and wild-type mice were assessed behaviourally following acute administration of 10 mg/kg morphine. Treatment with morphine reduced locomotion and rearing similarly in both genotypes but reduced total grooming only in MUT mice. Morphine-induced Straub tail and stillness were heightened in MUT mice. Chewing and sifting were decreased in MUT mice and these effects were not modified by morphine. Loss of striatal Drd1-positive cells and up-regulated D(2)-expression, as reflected in down-regulated D(1)-like and up-regulated D(2)-like binding, respectively, is not uniform along the cranio-caudal extent in this model but appears to be greater in the caudal striatum. Preferential caudal loss of µ-opioid-expression, a marker for the striosomal compartment, was seen. These data indicate that Drd1a-positive cell loss modifies the exploratory behavioural response elicited by morphine, unmasking novel morphine-induced MUT-specific behaviours and generating a hypersensitivity to morphine for others.
Asunto(s)
Conducta Animal/efectos de los fármacos , Ratones Mutantes/genética , Ratones Mutantes/psicología , Morfina/farmacología , Receptores de Dopamina D1/antagonistas & inhibidores , Animales , Núcleo Caudado/metabolismo , Femenino , Masculino , Ratones , Morfina/administración & dosificación , Receptores de Dopamina D1/metabolismo , Receptores de Dopamina D2/metabolismo , Receptores Opioides mu/metabolismoRESUMEN
Among numerous mechanisms implicated in the regulation of orofacial movements, dopamine-containing neurons have received the most extensive study. Here we review the effects of a) constitutive knockout of D(1-5) dopamine receptors and b) conditional mutations with progressive ablation of D(1) receptor-expressing cells, on the topography of spontaneous and D(1)-like agonist-induced orofacial movements. In constitutive knockouts, D(1) and D(2) exert primary roles in regulating horizontal and vertical jaw movements, respectively, in opposite directions; in contrast, both D(1) and D(2) receptors regulate tongue protrusions and incisor chattering, in the same direction. D(3) and D(5) receptors play more subtle roles in regulating orofacial movements, while D(4) receptors do not play any material role. Progressive loss of forebrain D(1) receptor-expressing cells in CamKIIa/Cre D(1)Tox mutants is associated primarily with decreases in head and vibrissae movements, while progressive loss of striatal D(1) receptor-expressing cells in DARPP-32/Cre D(1)Tox mutants is associated primarily with reductions in jaw movements and tongue protrusions but increases in head and vibrissae movements. Further application of constitutive and particularly conditional mutants may clarify further not only dopaminergic regulation of orofacial movements but also the pathophysiology of orofacial dysfunction in Huntington's disease and Parkinson's disease.
Asunto(s)
Cara/fisiología , Ratones Transgénicos , Movimiento/fisiología , Receptores Dopaminérgicos/fisiología , Animales , RatonesRESUMEN
BACKGROUND: The noninvasive evaluation of nigrostriatal dopaminergic integrity by PET can provide useful information for the differential diagnosis between dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). OBJECTIVES: To evaluate the diagnostic potential of imaging striatal monoaminergic terminal integrity with the novel vesicular monoamine transporter type 2 (VMAT2) radioligand [(18)F]AV-133 and PET to distinguish DLB from AD. METHODS: Fifty participants [9 DLB, 11 AD, 20 Parkinson's disease (PD) and 10 healthy age-matched control subjects (HC)] underwent [(18)F]AV-133 PET studies. Additionally, 20 participants underwent amyloid imaging PET scans with either [(11)C]PiB or (18)F-florbetaben. VMAT2 density was calculated through normalized tissue uptake value ratios (R(T)) at 120-140 min after injection using the primary visual or the cerebellar cortex as reference region. Comparison of the R(T) for [(18)F]AV-133 was done between the different clinical diagnostic groups. RESULTS: Significantly lower striatal VMAT2 densities were observed in DLB and PD when compared to AD and HC, especially in the posterior putamen. In contrast to PD and DLB, no reductions were observed in AD patients when compared to HC. CONCLUSIONS: [(18)F]AV-133 allows assessment of nigrostriatal degeneration in Lewy body diseases. In contrast to amyloid imaging, VMAT2 imaging with [(18)F]AV-133 can robustly detect reductions of dopaminergic nigrostriatal afferents in DLB patients, assisting in the differential diagnosis from AD.
Asunto(s)
Enfermedad de Alzheimer/diagnóstico por imagen , Amígdala del Cerebelo/diagnóstico por imagen , Amígdala del Cerebelo/patología , Enfermedad por Cuerpos de Lewy/diagnóstico por imagen , Proteínas de Transporte Vesicular de Monoaminas/metabolismo , Anciano , Anciano de 80 o más Años , Compuestos de Anilina , Mapeo Encefálico , Radioisótopos de Carbono , Estudios de Casos y Controles , Cuerpo Estriado/diagnóstico por imagen , Cuerpo Estriado/patología , Diagnóstico Diferencial , Femenino , Radioisótopos de Flúor , Humanos , Masculino , Persona de Mediana Edad , Tomografía de Emisión de Positrones/métodos , Tetrabenazina/análogos & derivados , TiazolesRESUMEN
There is a need for objective measures of dyskinesia and bradykinesia of Parkinson's disease (PD) that are continuous throughout the day and related to levodopa dosing. The output of an algorithm that calculates dyskinesia and bradykinesia scores every two minutes over 10 days (PKG: Global Kinetics Corporation) was compared with conventional rating scales for PD in PD subjects. The algorithm recognises bradykinesia as movements made with lower acceleration and amplitude and with longer intervals between movement. Similarly the algorithm recognises dyskinesia as having movements of normal amplitude and acceleration but with shorter periods without movement. The distribution of the bradykinesia and dyskinesia scores from PD subjects differed from that of normal subjects. The algorithm predicted the clinical dyskinesia rating scale AIMS with a 95% margin of error of 3.2 units compared with the inter-rater 95% limits of agreement from 3 neurologists of -3.4 to +4.3 units. Similarly the algorithm predicted the UPDRS III score with a margin of error similar to the inter-rater limits of agreement. Improvement in scores in response to changes in medication could be assessed statistically in individual patients. This algorithm provides objective, continuous and automated assessment of the clinical features of bradykinesia and dyskinesia in PD.
Asunto(s)
Discinesias/diagnóstico , Discinesias/etiología , Procesamiento Automatizado de Datos , Hipocinesia/diagnóstico , Hipocinesia/etiología , Enfermedad de Parkinson/complicaciones , Adulto , Algoritmos , Antiparkinsonianos/efectos adversos , Antiparkinsonianos/uso terapéutico , Estudios de Casos y Controles , Femenino , Humanos , Levodopa/efectos adversos , Masculino , Enfermedad de Parkinson/tratamiento farmacológico , Análisis Espectral , Factores de TiempoRESUMEN
Sodium appetite is an instinct that involves avid specific intention. It is elicited by sodium deficiency, stress-evoked adrenocorticotropic hormone (ACTH), and reproduction. Genome-wide microarrays in sodium-deficient mice or after ACTH infusion showed up-regulation of hypothalamic genes, including dopamine- and cAMP-regulated neuronal phosphoprotein 32 kDa (DARPP-32), dopamine receptors-1 and -2, α-2C- adrenoceptor, and striatally enriched protein tyrosine phosphatase (STEP). Both DARPP-32 and neural plasticity regulator activity-regulated cytoskeleton associated protein (ARC) were up-regulated in lateral hypothalamic orexinergic neurons by sodium deficiency. Administration of dopamine D1 (SCH23390) and D2 receptor (raclopride) antagonists reduced gratification of sodium appetite triggered by sodium deficiency. SCH23390 was specific, having no effect on osmotic-induced water drinking, whereas raclopride also reduced water intake. D1 receptor KO mice had normal sodium appetite, indicating compensatory regulation. Appetite was insensitive to SCH23390, confirming the absence of off-target effects. Bilateral microinjection of SCH23390 (100 nM in 200 nL) into rats' lateral hypothalamus greatly reduced sodium appetite. Gene set enrichment analysis in hypothalami of mice with sodium appetite showed significant enrichment of gene sets previously linked to addiction (opiates and cocaine). This finding of concerted gene regulation was attenuated on gratification with perplexingly rapid kinetics of only 10 min, anteceding significant absorption of salt from the gut. Salt appetite and hedonic liking of salt taste have evolved over >100 million y (e.g., being present in Metatheria). Drugs causing pleasure and addiction are comparatively recent and likely reflect usurping of evolutionary ancient systems with high survival value by the gratification of contemporary hedonic indulgences. Our findings outline a molecular logic for instinctive behavior encoded by the brain with possible important translational-medical implications.
Asunto(s)
Apetito/genética , Conducta Adictiva/genética , Hipotálamo/fisiología , Sodio en la Dieta/administración & dosificación , Hormona Adrenocorticotrópica/administración & dosificación , Hormona Adrenocorticotrópica/fisiología , Animales , Apetito/efectos de los fármacos , Apetito/fisiología , Conducta Adictiva/fisiopatología , Evolución Biológica , Ingestión de Líquidos/efectos de los fármacos , Ingestión de Líquidos/genética , Ingestión de Líquidos/fisiología , Femenino , Estudio de Asociación del Genoma Completo , Hipotálamo/efectos de los fármacos , Instinto , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Modelos Psicológicos , Análisis de Secuencia por Matrices de Oligonucleótidos , Ratas , Ratas Sprague-Dawley , RecompensaRESUMEN
OBJECTIVE: To assess the diagnostic potential of imaging striatal monoaminergic terminal integrity with the vesicular monoamine transporter type 2 (VMAT2) radioligand (18)F 9-fluropropyl-(+)-dihydrotetrabenazine ([(18)F]AV-133) and positron emission tomography to distinguish dementia with Lewy bodies (DLB) from Alzheimer disease (AD). DESIGN, SETTING, AND PARTICIPANTS: Nine patients with DLB, 10 patients with AD, 20 patients with Parkinson disease (PD), and 10 healthy age-matched control subjects underwent [(18)F]AV-133 positron emission tomography studies. VMAT2 density was calculated through normalized tissue uptake value ratios at 120 to 140 minutes postinjection using the primary visual cortex as the reference region. MAIN OUTCOME MEASURE: Comparison of the tissue ratio for [(18)F]AV-133 between the different clinical diagnostic groups. RESULTS: Lower VMAT2 densities were observed in patients with DLB when compared with patients with AD especially in the posterior putamen (caudate: mean [SD], 1.24 [0.6] vs 2.83 [0.9]; P < .001; effect size = 2.1; anterior putamen: mean [SD], 0.90 [0.5] vs 3.01 [0.9]; P < .001; effect size = 2.9; posterior putamen: mean [SD], 0.62 [0.5] vs 2.87 [0.8]; P < .001; effect size = 3.4). Compared with healthy controls, [(18)F]AV-133 tissue ratios were significantly lower by 88% and 74% in the posterior putamen, 74% and 65% in the anterior putamen, and 53% and 51% in the caudate nucleus of patients with PD and DLB, respectively. In contrast to patients with PD and DLB, no reductions were observed in patients with AD. CONCLUSIONS: [(18)F]AV-133 allows assessment of nigrostriatal degeneration in Lewy body diseases. [(18)F]AV-133 can robustly detect reductions of dopaminergic nigrostriatal afferents in patients with DLB and assist in the differential diagnosis from AD.
Asunto(s)
Enfermedad de Alzheimer/diagnóstico por imagen , Enfermedad por Cuerpos de Lewy/diagnóstico por imagen , Tetrabenazina/análogos & derivados , Proteínas de Transporte Vesicular de Monoaminas/metabolismo , Anciano , Anciano de 80 o más Años , Área Bajo la Curva , Mapeo Encefálico , Femenino , Radioisótopos de Flúor , Humanos , Masculino , Persona de Mediana Edad , Tomografía de Emisión de Positrones/métodos , Curva ROCRESUMEN
The loss of nigral dopaminergic (DA) neurons is the disease-defining pathological change responsible for progressive motor dysfunction in Parkinson's disease. In this study, we sought to establish a culture method for adult rat tyrosine hydroxylase (TH)-immunoreactive DA neurons. In this context, we investigated the role of fibroblast growth factor 2 (FGF2), brain-derived neurotrophic factor (BDNF), transforming growth factor-ß3 (TGF-ß3), glial-derived neurotrophic factor (GDNF) and dibutyryl-cyclic AMP (dbcAMP) in these cultures. Culturing in the presence of FGF2, BDNF and GDNF enhanced the survival of DA neurons by 15-fold and promoted neurite growth. In contrast, dbcAMP promoted neurite growth in all neurons but did not enhance DA cell survival. This study demonstrates that long-term cultures of DA neurons can be established from the mature rat brain and that survival and regeneration of DA neurons can be manipulated by epigenetic factors such as growth factors and intracellular cAMP pathways.
Asunto(s)
Encéfalo/enzimología , Dopamina/metabolismo , Neuronas/enzimología , Regeneración , Tirosina 3-Monooxigenasa/metabolismo , Animales , Encéfalo/citología , Encéfalo/metabolismo , Femenino , Técnicas In Vitro , Neuronas/metabolismo , Ratas , Ratas Sprague-DawleyRESUMEN
Here we utilize a mouse line with a targeted deletion of the α4 subunit (α4-/- mice), to investigate the role of α4* nAChRs in reinforcing and locomotor effects of nicotine. Within a conditioned place preference paradigm, both α4-/- mice and wild-type (WT) littermates showed a similar place preference to nicotine (0.5 mg/kg i.p.) conditioning. When assessed for operant intravenous self-administration of nicotine (0.05 mg/kg/infusion), α4-/- mice did not differ from their WT littermates in self-administration behavior. To further examine a modulatory role for α4* nAChRs in the reinforcing effects of nicotine, a transgenic mouse with a point mutation of the α4 subunit (α4-S248F) that renders increased sensitivity to low dose nicotine, was assessed for nicotine self-administration over a range of doses. At higher doses examined (0.05 and 0.07 mg/kg/infusion) there was no difference in intravenous nicotine self-administration; however, when mice were offered a lower dose of nicotine (0.03 mg/kg/infusion), α4-S248F mice showed greater nicotine intake than controls. Acute administration of 0.5 mg/kg nicotine caused significant locomotor depression in WT mice but α4-/- mice instead showed significant hyperactivity. Following chronic, intermittent administration of this dose of nicotine only WT mice displayed significant tolerance. Analogous experiments utilizing administration of the nicotinic antagonist mecamylamine in WT mice confirmed a dissociation between the putative nicotinic receptor subtypes required for mediating psychomotor and reinforcing effects of nicotine. These data demonstrate a necessary role for α4* nAChRs in the locomotor depressant effect of nicotine but not the reinforcing effects that support ongoing self-administration of nicotine.