RESUMEN
Vascular cognitive impairment (VCI) is associated with chronic cerebral hypoperfusion (CCH) and memory deficits, and often occurs concurrently with metabolic syndrome (MetS). Despite their common occurrence, it is unknown whether CCH and MetS act synergistically to exacerbate VCI-associated pathology. Here, using male Sprague-Dawley rats, we examined the effects of a clinically relevant model of adolescent-onset MetS and adult-onset CCH on neuro-vascular outcomes, combining a cafeteria diet with a 2-vessel occlusion (2VO) model. Using longitudinal imaging, histology, and behavioural assessments, we identified several features of MetS and CCH including reduced cerebral blood volume, white matter atrophy, alterations in hippocampal cell density, and memory impairment. Furthermore, we identified a number of significant associations, potentially predictive of MetS and pathophysiological outcomes. White matter volume was positively correlated to HDL cholesterol; hippocampal cell density was negatively correlated to fasted blood glucose; cerebral blood flow and volume was negatively predicted by the combination of 2VO surgery and increased fasted blood glucose. These results emphasize the importance of including comorbid conditions when modeling VCI, and they outline a highly translational preclinical model that could be used to investigate potential interventions to mitigate VCI-associated pathology and cognitive decline.
Asunto(s)
Isquemia Encefálica/patología , Cognición/fisiología , Síndrome Metabólico/patología , Perfusión , Animales , Isquemia Encefálica/metabolismo , Disfunción Cognitiva/patología , Modelos Animales de Enfermedad , Síndrome Metabólico/fisiopatología , Ratas Sprague-DawleyRESUMEN
BACKGROUND: The proportional recovery rule suggests that current rehabilitation practices may have limited ability to influence stroke recovery. However, the appropriate intensity of rehabilitation needed to achieve recovery remains unknown. Similarities between rodent and human recovery biomarkers may allow determination of rehabilitation thresholds necessary to activate endogenous biological recovery processes. OBJECTIVE: We determined the relative influence that clinically relevant biomarkers of stroke recovery exert on functional outcome. These biomarkers were then used to generate an algorithm that prescribes individualized intensities of rehabilitation necessary for recovery of function. METHODS: A retrospective cohort of 593 male Sprague-Dawley rats was used to identify biomarkers that best predicted poststroke change in pellet retrieval in the Montoya staircase-reaching task using multiple linear regression. Prospective manipulation of these factors using endothelin-1-induced stroke (n = 49) was used to validate the model. RESULTS: Rehabilitation was necessary to reliably predict recovery across the continuum of stroke severity. As infarct volume and initial impairment increased, more intensive rehabilitation was required to engage recovery. In this model, we prescribed the specific dose of daily rehabilitation required for rats to achieve significant motor recovery using the biomarkers of initial poststroke impairment and infarct volume. CONCLUSIONS: Our algorithm demonstrates an individualized approach to stroke rehabilitation, wherein imaging and functional performance measures can be used to develop an optimized rehabilitation paradigm for rats, particularly those with severe impairments. Exploring this approach in human patients could lead to an increase in the proportion of individuals experiencing recovery of lost motor function poststroke.
Asunto(s)
Actividad Motora/fisiología , Recuperación de la Función/fisiología , Rehabilitación de Accidente Cerebrovascular/métodos , Algoritmos , Animales , Biomarcadores , Modelos Animales de Enfermedad , Masculino , Medicina de Precisión , Ratas , Ratas Sprague-Dawley , Estudios RetrospectivosRESUMEN
To better understand the effects of a diet high in fat, sugar, and sodium on cerebrovascular function, Sprague Dawley rats were chronically exposed to a Cafeteria diet. Resting cerebral perfusion and cerebrovascular reactivity was quantified using continuous arterial spin labeling (CASL) magnetic resonance imaging (MRI). In addition, structural changes to the cerebrovasculature and susceptibility to ischemic lesion were examined. Compared to control animals fed standard chow (SD), Cafeteria diet (CAF) rats exhibited increased resting brain perfusion in the hippocampus and reduced cerebrovascular reactivity in response to 10% inspired CO2 challenges in both the hippocampus and the neocortex. CAF rats switched to chow for one month (SWT) exhibited improved resting perfusion in the hippocampus as well as improved cerebrovascular reactivity in the neocortex. However, the diet switch did not correct cerebrovascular reactivity in the hippocampus. These changes were not accompanied by alterations in the structural integrity of the cerebral microvasculature, examined using rat endothelial cell antigen-1 (RECA-1) and immunoglobulin G (IgG) immunostaining. Also, the extent of tissue damage induced by endothelin-1 injection into sensorimotor cortex was not affected by the Cafeteria diet. These results demonstrate that short-term consumption of an ultra-processed diet reduces cerebrovascular reactivity. This effect persists after dietary normalization despite recovery of peripheral symptomatology.
Asunto(s)
Circulación Cerebrovascular/fisiología , Dieta Occidental/efectos adversos , Hemodinámica/fisiología , Animales , Barrera Hematoencefálica/diagnóstico por imagen , Barrera Hematoencefálica/metabolismo , Barrera Hematoencefálica/patología , Corteza Cerebral/irrigación sanguínea , Corteza Cerebral/diagnóstico por imagen , Corteza Cerebral/metabolismo , Corteza Cerebral/patología , Modelos Animales de Enfermedad , Endotelina-1 , Hipocampo/irrigación sanguínea , Hipocampo/diagnóstico por imagen , Hipocampo/metabolismo , Hipocampo/patología , Masculino , Síndrome Metabólico/diagnóstico por imagen , Síndrome Metabólico/metabolismo , Síndrome Metabólico/patología , Distribución Aleatoria , Ratas Sprague-Dawley , Accidente Cerebrovascular/metabolismo , Accidente Cerebrovascular/patologíaRESUMEN
Many promising findings from pre-clinical research have failed to translate to the clinic due to their inability to incorporate human disease co-morbidity. A variety of rodent diets and feeding durations are currently used in models of human metabolic syndrome, obesity and diabetes. One model, the Cafeteria (CAF) diet, makes use of grocery store-purchased food items that more closely approximate the human ultra-processed diet than commercial high-fat or high-sugar rodent diets. The present study describes the development of metabolic syndrome in rats fed a CAF diet as well as the recovery of metabolic syndrome following a healthy "lifestyle" change. In addition, we explored the effects of CAF diet on spatial learning and memory and on neuroinflammation. Three-week old male Sprague-Dawley rats were fed a CAF diet for three months that consisted of 16 highly palatable human food items along with standard chow and a 12% sucrose solution to mimic soda consumption. Thereafter, a sub-group of CAF diet rats was switched to a chow diet (SWT) for one month. Both CAF and SWT groups were compared to control rats maintained on a standard chow diet (SD). Prior to the diet switch, CAF and SWT animals developed features akin to metabolic syndrome. Both groups of rats displayed significant abdominal obesity with increased visceral adiposity, hyperinsulinemia, glucose intolerance and dyslipidemia with elevated serum triglyceride levels and reduced HDL cholesterol. Switching to a chow diet for one month completely reversed these features in SWT animals. Although acquisition of the Barnes maze was not affected by the CAF diet, these animals exhibited greater hippocampal neuroinflammation compared to both SD and SWT rats as assessed by Iba1 staining. These results demonstrate that the CAF diet is very effective in creating metabolic syndrome with hippocampal inflammation in rats over a relatively short time span. This model may be of great heuristic importance in determining potential reversibility of metabolic and cerebrovascular pathologies across the lifespan and as a co-morbid factor in other disease models such as stroke.
Asunto(s)
Dieta/efectos adversos , Enfermedades Metabólicas/fisiopatología , Análisis de Varianza , Animales , Peso Corporal , Proteínas de Unión al Calcio/metabolismo , Modelos Animales de Enfermedad , Ingestión de Energía , Prueba de Tolerancia a la Glucosa , Grasa Intraabdominal/diagnóstico por imagen , Imagen por Resonancia Magnética , Masculino , Aprendizaje por Laberinto , Enfermedades Metabólicas/sangre , Enfermedades Metabólicas/diagnóstico por imagen , Proteínas de Microfilamentos/metabolismo , Ratas , Ratas Sprague-Dawley , Grasa Subcutánea/diagnóstico por imagenRESUMEN
Despite continuous improvement in neonatology there is no clinically effective treatment for perinatal hypoxia ischemia (HI). Therefore, development of a new therapeutic intervention to minimize the resulting neurological consequences is urgently needed. The immature brain is highly responsive to environmental stimuli, such as environmental enrichment but a more effective paradigm is enriched rehabilitation (ER), which combines environmental enrichment with daily reach training. Another neurorestorative strategy to promote tissue repair and functional recovery is cyclosporine A (CsA). However, potential benefits of CsA after neonatal HI have yet to be investigated. The aim of this study was to investigate the effects of a combinational therapy of CsA and ER in attempts to promote cognitive and motor recovery in a rat model of perinatal hypoxic-ischemic injury. Seven-day old rats were submitted to the HI procedure and divided into 4 groups: CsA+Rehabilitation; CsA+NoRehabilitation; Vehicle+Rehabilitation; Vehicle+NoRehabilitation. Behavioural parameters were evaluated pre (experiment 1) and post 4 weeks of combinational therapy (experiment 2). Results of experiment 1 demonstrated reduced open field activity of HI animals and increased foot faults relative to shams in the ladder rung walking test. In experiment 2, we showed that ER facilitated acquisition of a staircase skilled-reaching task, increased number of zone crosses in open-field exploration and enhanced coordinated limb use during locomotion on the ladder rung task. There were no evident deficits in novel object recognition testing. Delayed administration of CsA, had no effect on functional recovery after neonatal HI. There was a significant reduction of cortical and hemispherical volume and hippocampal area, ipsilateral to arterial occlusion in HI animals; combinational therapy had no effect on these morphological measurements. In conclusion, the present study demonstrated that ER, but not CsA was the main contributor to enhanced recovery of motor ability after neonatal HI.
Asunto(s)
Ambiente , Hipoxia-Isquemia Encefálica/fisiopatología , Hipoxia-Isquemia Encefálica/rehabilitación , Actividad Motora/fisiología , Recuperación de la Función/fisiología , Factores de Edad , Animales , Animales Recién Nacidos , Infarto Encefálico/tratamiento farmacológico , Infarto Encefálico/etiología , Infarto Encefálico/rehabilitación , Trastornos del Conocimiento/tratamiento farmacológico , Trastornos del Conocimiento/etiología , Trastornos del Conocimiento/rehabilitación , Ciclosporina/uso terapéutico , Conducta Exploratoria/efectos de los fármacos , Conducta Exploratoria/fisiología , Conducta Alimentaria/efectos de los fármacos , Conducta Alimentaria/fisiología , Femenino , Hipoxia-Isquemia Encefálica/tratamiento farmacológico , Inmunosupresores/uso terapéutico , Masculino , Embarazo , Desempeño Psicomotor/efectos de los fármacos , Desempeño Psicomotor/fisiología , Ratas , Ratas Sprague-Dawley , Reconocimiento en Psicología/efectos de los fármacos , Reconocimiento en Psicología/fisiología , Recuperación de la Función/efectos de los fármacosRESUMEN
Stroke is the second leading cause of death and the preeminent cause of neurological disability. Attempts to limit brain injury after ischemic stroke with clot-dissolving drugs have met with great success but their use remains limited due to a narrow therapeutic time window and concern over serious side effects. Unfortunately, the neuroprotective strategy failed in clinical trials. A more promising approach is to promote recovery of function in people affected by stroke. Following stroke, there is a heightened critical period of plasticity that appears to be receptive to exogenous interventions (e.g., delivery of growth factors) designed to enhance neuroplasticity processes important for recovery. An emerging concept is that combinational therapies appear much more effective than single interventions in improving stroke recovery. One of the most promising interventions, with clinical feasibility, is enriched rehabilitation, a combination of environmental enrichment and task-specific therapy.
Asunto(s)
Ambiente , Plasticidad Neuronal/fisiología , Recuperación de la Función/fisiología , Accidente Cerebrovascular/terapia , Animales , Humanos , Accidente Cerebrovascular/fisiopatologíaRESUMEN
BACKGROUND: Endothelin-1 (ET-1) induced focal ischemia is increasingly being used as a preclinical model of stroke. Here, we described for the first time, the time course of neuronal death and infarct evolution during the first 7 days following ischemia. NEW METHOD: We used hematoxylin and eosin (H&E) staining to evaluate infarct progression and Fluoro-Jade C (FJC) to quantify neuronal degeneration at 24, 48, 72h and 7 days after ET-1 injection to the forelimb motor cortex in Sprague-Dawley rats. RESULTS: We found that infarct volume and neuronal degeneration are maximal at 24h post-stroke. Neuronal degeneration is also significantly reduced within 7 days of stroke induction. COMPARISON WITH EXISTING METHOD: This study is the first to provide a direct evaluation of both infarct volume evolution and neuronal death time course following ET-1 induced focal ischemia in the forelimb motor cortex. CONCLUSION: This study describes the short-term time course of neuronal death and brain injury in the ET-1 stroke model, which provides a significant reference when determining the appropriate time to commence neuroprotective or recovery promoting strategies.
Asunto(s)
Isquemia Encefálica/fisiopatología , Muerte Celular/fisiología , Corteza Motora/fisiopatología , Neuronas/fisiología , Accidente Cerebrovascular/fisiopatología , Animales , Isquemia Encefálica/patología , Recuento de Células , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Endotelina-1 , Miembro Anterior , Masculino , Corteza Motora/patología , Degeneración Nerviosa/etiología , Degeneración Nerviosa/patología , Degeneración Nerviosa/fisiopatología , Neuronas/patología , Ratas Sprague-Dawley , Accidente Cerebrovascular/patología , Factores de TiempoRESUMEN
BACKGROUND: Stroke is a devastating disorder that strikes approximately 15 million people worldwide. While most patients survive stroke, many are left with lifelong impairments, thereby making stroke the leading cause of permanent neurological disability. Despite this, there are a few options for treatment of acute stroke. Restoration of blood flow using clot-dissolving drugs has produced impressive benefits in some patients. However, for these drugs to be effective, they must be given soon after stroke onset and relatively only a few stroke patients reach hospital within this time. Side effects of these compounds further limit their use. SUMMARY: Enhancing the brain's endogenous capacity for reorganization and self-repair offers the most promise for victims of stroke. Indeed, many stroke patients show considerable spontaneous functional improvement. Findings in the last 15 years suggest that stroke and related injury create a cerebral milieu similar to that of early brain development, a period characterized by rapid neuronal growth and neuroplasticity. A variety of interventions (e.g., stem cells, delivery of growth factors) are currently being explored in order to enhance neuroplasticity and reorganizational processes that are important for recovery of function. An emerging concept is that combinational or 'cocktail' therapies are more effective than single interventions in improving stroke recovery. Among these, one of the most promising therapies is enriched rehabilitation, a combination of environmental enrichment and task-specific therapy (e.g., reach training). KEY MESSAGES: Neurorestorative approaches to brain reorganization and repair are providing new insights into how neural circuits respond to injury and how this knowledge can be used for optimizing stroke rehabilitation practice.
Asunto(s)
Encéfalo/fisiopatología , Terapia por Ejercicio , Regeneración Nerviosa , Plasticidad Neuronal , Psicoterapia/métodos , Trasplante de Células Madre , Rehabilitación de Accidente Cerebrovascular , Animales , Encéfalo/patología , Terapia Combinada , Evaluación de la Discapacidad , Humanos , Recuperación de la Función , Accidente Cerebrovascular/diagnóstico , Accidente Cerebrovascular/fisiopatología , Accidente Cerebrovascular/psicología , Factores de Tiempo , Resultado del TratamientoRESUMEN
Protein tyrosine phosphatase 1B (PTP1B) counteracts leptin signaling and is a therapeutic target for obesity and diabetes. Here we found that LIM domain only 4 (LMO4) inhibits PTP1B activity by increasing the oxidized inactive form of PTP1B. Mice with neuronal ablation of LMO4 have elevated PTP1B activity and impaired hypothalamic leptin signaling, and a PTP1B inhibitor normalized PTP1B activity and restored leptin control of circulating insulin levels. LMO4 is palmitoylated at its C-terminal cysteine, and deletion of this residue prevented palmitoylation and retention of LMO4 at the endoplasmic reticulum and abolished its inhibitory effect on PTP1B. Importantly, LMO4 palmitoylation is sensitive to metabolic stress; mice challenged with a brief high-fat diet or acute intracerebroventricular infusion of saturated fatty acid had less palmitoylated LMO4, less oxidized PTP1B, and increased PTP1B activity in the hypothalamus. Thus, unleashed PTP1B activity attributable to loss of LMO4 palmitoylation may account for rapid loss of central leptin signaling after acute exposure to saturated fat.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Hipotálamo/metabolismo , Proteínas con Dominio LIM/metabolismo , Leptina/metabolismo , Proteína Tirosina Fosfatasa no Receptora Tipo 1/metabolismo , Transducción de Señal/fisiología , Proteínas Adaptadoras Transductoras de Señales/deficiencia , Glándulas Suprarrenales/efectos de los fármacos , Glándulas Suprarrenales/metabolismo , Animales , Proteínas Bacterianas/genética , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/genética , Peso Corporal/efectos de los fármacos , Peso Corporal/genética , Línea Celular Transformada , Colestanos/administración & dosificación , Retículo Endoplásmico/efectos de los fármacos , Prueba de Tolerancia a la Glucosa , Homeostasis/efectos de los fármacos , Homeostasis/genética , Hipotálamo/ultraestructura , Técnicas In Vitro , Infusiones Intraventriculares , Resistencia a la Insulina , Proteínas con Dominio LIM/deficiencia , Proteínas Luminiscentes/genética , Ratones , Ratones Noqueados , Norepinefrina/metabolismo , Páncreas/efectos de los fármacos , Páncreas/metabolismo , Ratas , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Espermina/administración & dosificación , Espermina/análogos & derivadosRESUMEN
The LIM domain only 4 (LMO4) transcription cofactor activates gene expression in neurons and regulates key aspects of network formation, but the mechanisms are poorly understood. Here, we show that LMO4 positively regulates ryanodine receptor type 2 (RyR2) expression, thereby suggesting that LMO4 regulates calcium-induced calcium release (CICR) in central neurons. We found that CICR modulation of the afterhyperpolarization in CA3 neurons from mice carrying a forebrain-specific deletion of LMO4 (LMO4 KO) was severely compromised but could be restored by single-cell overexpression of LMO4. In line with these findings, two-photon calcium imaging experiments showed that the potentiation of RyR-mediated calcium release from internal stores by caffeine was absent in LMO4 KO neurons. The overall facilitatory effect of CICR on glutamate release induced during trains of action potentials was likewise defective in LMO4 KO, confirming that CICR machinery is severely compromised in these neurons. Moreover, the magnitude of CA3-CA1 long-term potentiation was reduced in LMO4 KO mice, a defect that appears to be secondary to an overall reduced glutamate release probability. These cellular phenotypes in LMO4 KO mice were accompanied with deficits in hippocampus-dependent spatial learning as determined by the Morris water maze test. Thus, our results establish LMO4 as a key regulator of CICR in central neurons, providing a mechanism for LMO4 to modulate a wide range of neuronal functions and behavior.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Calcio/metabolismo , Hipocampo/citología , Proteínas con Dominio LIM/metabolismo , Plasticidad Neuronal/fisiología , Neuronas/metabolismo , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/genética , Proteínas Adaptadoras Transductoras de Señales/deficiencia , Proteínas Adaptadoras Transductoras de Señales/genética , Análisis de Varianza , Animales , Cafeína/farmacología , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/genética , Células Cultivadas , Maleato de Dizocilpina/farmacología , Estimulación Eléctrica , Antagonistas de Aminoácidos Excitadores/farmacología , Potenciales Postsinápticos Excitadores/efectos de los fármacos , Potenciales Postsinápticos Excitadores/genética , Potenciales Postsinápticos Excitadores/fisiología , Regulación de la Expresión Génica/genética , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Hibridomas , Proteínas con Dominio LIM/deficiencia , Proteínas con Dominio LIM/genética , Aprendizaje por Laberinto/fisiología , Ratones , Ratones Transgénicos , Plasticidad Neuronal/genética , Neuronas/efectos de los fármacos , Técnicas de Cultivo de Órganos , Técnicas de Placa-Clamp , Inhibidores de Fosfodiesterasa/farmacología , ARN Mensajero/metabolismo , Ratas , Canal Liberador de Calcio Receptor de Rianodina/genética , TransfecciónRESUMEN
The LIM domain only 4 (LMO4) protein is expressed in the hypothalamus, but its function there is not known. Using mice with LMO4 ablated in postnatal glutamatergic neurons, including most neurons of the paraventricular (PVN) and ventromedial (VMH) hypothalamic nuclei where LMO4 is expressed, we asked whether LMO4 is required for metabolic homeostasis. LMO4 mutant mice exhibited early onset adiposity. These mice had reduced energy expenditure and impaired thermogenesis together with reduced sympathetic outflow to adipose tissues. The peptide hormone leptin, produced from adipocytes, activates Jak/Stat3 signaling at the hypothalamus to control food intake, energy expenditure, and fat metabolism. Intracerebroventricular infusion of leptin suppressed feeding similarly in LMO4 mutant and control mice. However, leptin-induced fat loss was impaired and activation of Stat3 in the VMH was blunted in these mice. Thus, our study identifies LMO4 as a novel modulator of leptin function in selective hypothalamic nuclei to regulate fat metabolism.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas con Dominio LIM/metabolismo , Leptina/metabolismo , Metabolismo de los Lípidos , Proteínas Adaptadoras Transductoras de Señales/deficiencia , Proteínas Adaptadoras Transductoras de Señales/genética , Tejido Adiposo/metabolismo , Animales , Metabolismo Energético , Quinasas Janus/metabolismo , Proteínas con Dominio LIM/deficiencia , Proteínas con Dominio LIM/genética , Masculino , Ratones , Ratones Noqueados , Neuronas/metabolismo , Obesidad/metabolismo , Obesidad/fisiopatología , Factor de Transcripción STAT3/metabolismo , Transducción de Señal , Núcleo Hipotalámico Ventromedial/metabolismoRESUMEN
Granulocyte colony-stimulating factor (GCSF) is currently in clinical trials to treat neurodegenerative diseases and stroke. Here, we tested whether LIM domain only 4 protein (LMO4), a hypoxia-inducible gene that protects neurons from ischemic injury, could modulate the neuroprotective effect of GCSF. We showed that GCSF treatment acetylates and phosphorylates Stat3, activates expression of a Stat3-dependent anti-apoptotic gene, p27, and increases neuron survival from ischemic injury. LMO4 participates in Stat3 signaling in hepatocytes and associates with histone deacetylase 2 (HDAC2) in cancer cells. In the absence of LMO4, GCSF fails to rescue neurons from ischemic insults. In wild-type neurons, inhibition of HDAC promoted Stat3 acetylation and the antiapoptotic effect of GCSF. In LMO4 null cortical neurons, expression of wild-type but not HDAC-interaction-deficient LMO4 restored GCSF-induced Stat3 acetylation and p27 expression. Thus, our results indicate that LMO4 enhances GCSF-induced Stat3 signaling in neurons, in part by sequestering HDAC.