RESUMEN
AIM: The aim was to evaluate the beneficial effect of early mitogen-activated protein kinase (MEK)1/2 inhibition administered at a clinical relevant time-point using the transient middle cerebral artery occlusion model and a dedicated rodent magnetic resonance imaging system (9.4T) to monitor cerebrovascular changes non-invasively for 2 weeks. METHOD: Transient middle cerebral artery occlusion was induced in male rats for two hours followed by reperfusion. The specific MEK1/2 inhibitor U0126 was administered ip at 6 and 24 hours post-reperfusion. Neurological functions were evaluated by 6- and 28-point tests. 9.4 T magnetic resonance imaging was used to monitor morphological infarct changes at day 2, 8 and 14 after stroke and to evaluate cerebral perfusion at day 14. Immunohistochemistry evaluation of Ki67 was performed 14 days post-stroke. RESULTS: U0126 improved long-term behavioural outcome and significantly reduced infarct size. In addition, cerebral perfusion in U0126-treated animals was improved compared to the vehicle group. Immunohistochemistry showed a significant increase in Ki67+ cells in U0126-treated animals compared to the vehicle group. CONCLUSION: Early MEK1/2 inhibition improves long-term functional outcome, promotes recovery processes after stroke and most importantly provides a realistic time window for therapy.
Asunto(s)
Encéfalo/efectos de los fármacos , Butadienos/farmacología , Circulación Cerebrovascular/efectos de los fármacos , Infarto de la Arteria Cerebral Media/tratamiento farmacológico , MAP Quinasa Quinasa 1/antagonistas & inhibidores , MAP Quinasa Quinasa 2/antagonistas & inhibidores , Imagen por Resonancia Magnética , Nitrilos/farmacología , Inhibidores de Proteínas Quinasas/farmacología , Animales , Encéfalo/diagnóstico por imagen , Encéfalo/enzimología , Encéfalo/fisiopatología , Modelos Animales de Enfermedad , Infarto de la Arteria Cerebral Media/diagnóstico por imagen , Infarto de la Arteria Cerebral Media/enzimología , Infarto de la Arteria Cerebral Media/fisiopatología , Antígeno Ki-67/metabolismo , MAP Quinasa Quinasa 1/metabolismo , MAP Quinasa Quinasa 2/metabolismo , Masculino , Ratas Wistar , Recuperación de la Función , Factores de TiempoRESUMEN
AIM: Extracellular signal-regulated kinase (ERK) 1/2 is activated during acute phase of stroke and contributes to stroke pathology. We have found that acute treatment with MEK1/2 inhibitors decreases infarct size and neurological deficits 2 days after experimental stroke. However, it is not known whether benefits of this inhibition persist long-term. Therefore, the aim of this study was to assess neurological function, infarct size and recovery processes 14 days after stroke in male rats to determine long-term outcome following acute treatment with the MEK1/2 inhibitor U0126. METHODS: Transient middle cerebral artery occlusion was induced in male rats. U0126 or vehicle was given at 0 and 24 h of reperfusion. Neurological function was assessed by staircase, 6-point and 28-point neuroscore tests up to 14 days after induction of stroke. At day 14, infarct volumes were determined and recovery processes were evaluated by measuring protein expression of the tyrosine kinase receptor Tie-2 and nestin. Levels of p-ERK1/2 protein were determined. RESULTS: Acute treatment with U0126 significantly improved long-term functional recovery, reduced infarct size, and enhanced Tie-2 and nestin protein expression at 14 days post-stroke. There was no residual blockade of p-ERK1/2 at this time point. CONCLUSION: It is demonstrated that benefits of early treatment with U0126 persist beyond subacute phase of ischaemic stroke in male rats. Prevention of ERK1/2 activation in the acute phase results in improved long-term functional outcome and enhances later-stage recovery processes. These results expand our understanding of the benefits and promise of using MEK1/2 inhibitors in stroke recovery.
Asunto(s)
Encéfalo/enzimología , Proteína Quinasa 1 Activada por Mitógenos/antagonistas & inhibidores , Proteína Quinasa 3 Activada por Mitógenos/antagonistas & inhibidores , Recuperación de la Función/fisiología , Accidente Cerebrovascular/enzimología , Animales , Western Blotting , Encéfalo/efectos de los fármacos , Encéfalo/patología , Butadienos/farmacología , Modelos Animales de Enfermedad , Inhibidores Enzimáticos/farmacología , Procesamiento de Imagen Asistido por Computador , Inmunohistoquímica , Masculino , Nitrilos/farmacología , Ratas , Ratas Wistar , Recuperación de la Función/efectos de los fármacos , Accidente Cerebrovascular/patologíaRESUMEN
Varroa destructor, an ectoparasitic mite of honey bees (Apis mellifera), is the most serious pest threatening the apiculture industry. In our honey bee breeding programme, two honey bee colonies showing extreme phenotypes for varroa tolerance/resistance (S88) and susceptibility (G4) were identified by natural selection from a large gene pool over a 6-year period. To investigate potential defence mechanisms for honey bee tolerance to varroa infestation, we employed DNA microarray and real time quantitative (PCR) analyses to identify differentially expressed genes in the tolerant and susceptible colonies at pupa and adult stages. Our results showed that more differentially expressed genes were identified in the tolerant bees than in bees from the susceptible colony, indicating that the tolerant colony showed an increased genetic capacity to respond to varroa mite infestation. In both colonies, there were more differentially expressed genes identified at the pupa stage than at the adult stage, indicating that pupa bees are more responsive to varroa infestation than adult bees. Genes showing differential expression in the colony phenotypes were categorized into several groups based on their molecular functions, such as olfactory signalling, detoxification processes, exoskeleton formation, protein degradation and long-chain fatty acid metabolism, suggesting that these biological processes play roles in conferring varroa tolerance to naturally selected colonies. Identification of differentially expressed genes between the two colony phenotypes provides potential molecular markers for selecting and breeding varroa-tolerant honey bees.