RESUMEN
Docosahexaenoic acid (DHA) has been studied for many years owing to its protective effect on the decline in brain function. DHA intake reduces the risk of Alzheimer's disease (AD) and decreases amyloid deposition; however, the underlying molecular mechanism has not been completed elucidated. In this study, the effect of DHA on the cognitive function of amyloid precursor protein (APP)/PS1 in wild-type mice and its related mechanism were investigated. Results from the Morris water maze test showed that DHA improved learning and memory function in mice. Moreover, DHA reduced neuronal damage in mice brains, as determined using Nissl staining. Unsaturated fatty acid levels in the brain of mice increased (p < 0.01) after DHA administration and saturated fatty acid levels decreased (p < 0.01). The deposition of amyloid-beta (Aß) plaques and tau protein neurofibrillary tangles was significantly inhibited. The mechanism of action of DHA was attributed to the upregulation of the expression of ß-secretase (BACE)2, which competed with BACE1 to cleave APP, thus decreasing the production of extracellular Aß fragments (p < 0.01). The expression level of insulin-degrading enzyme was not significantly different. The expression of N-methyl-D-aspartate receptors was further downregulated and the phosphorylation of glycogen synthase kinase-3ß and tau protein was inhibited (p < 0.01). These data indicated that DHA could protect cognitive function in mice by reducing Aß plaque formation and decreasing tau phosphorylation levels.
Asunto(s)
Cognición/efectos de los fármacos , Ácidos Docosahexaenoicos/farmacología , Sustancias Protectoras/farmacología , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Femenino , Ratones , Ratones Transgénicos , Prueba del Laberinto Acuático de Morris/efectos de los fármacos , Fosforilación/efectos de los fármacos , Proteínas tau/metabolismoRESUMEN
The number of people with dementia worldwide is estimated at 50 million by 2018 and continues to rise mainly due to increasing aging and population growth. Clinical impact of current interventions remains modest and all efforts aimed at the identification of new therapeutic approaches are therefore critical. Previously, we showed that JM-20, a dihydropyridine-benzodiazepine hybrid molecule, protected memory processes against scopolamine-induced cholinergic dysfunction. In order to gain further insight into the therapeutic potential of JM-20 on cognitive decline and Alzheimer's disease (AD) pathology, here we evaluated its neuroprotective effects after chronic aluminum chloride (AlCl3) administration to rats and assessed possible alterations in several types of episodic memory and associated pathological mechanisms. Oral administration of aluminum to rodents recapitulates several neuropathological alterations and cognitive impairment, being considered a convenient tool for testing the efficacy of new therapies for dementia. We used behavioral tasks to test spatial, emotional- associative and novel object recognition memory, as well as molecular, enzymatic and histological assays to evaluate selected biochemical parameters. Our study revealed that JM-20 prevented memory decline alongside the inhibition of AlCl3 -induced oxidative stress, increased AChE activity, TNF-α and pro-apoptotic proteins (like Bax, caspase-3, and 8) levels. JM-20 also protected against neuronal damage in the hippocampus and prefrontal cortex. Our findings expanded our understanding of the ability of JM-20 to preserve memory in rats under neurotoxic conditions and confirm its potential capacity to counteract cognitive impairment and etiological factors of AD by breaking the progression of key steps associated with neurodegeneration.
Asunto(s)
Cloruro de Aluminio/toxicidad , Benzodiazepinas/farmacología , Trastornos de la Memoria/inducido químicamente , Memoria/efectos de los fármacos , Neuronas/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Niacina/análogos & derivados , Cloruro de Aluminio/antagonistas & inhibidores , Animales , Hipocampo/efectos de los fármacos , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Trastornos de la Memoria/tratamiento farmacológico , Mitocondrias/efectos de los fármacos , Prueba del Laberinto Acuático de Morris/efectos de los fármacos , Niacina/farmacología , Prueba de Campo Abierto/efectos de los fármacos , Corteza Prefrontal/efectos de los fármacos , Ratas , Ratas Wistar , Prueba de Desempeño de Rotación con Aceleración ConstanteRESUMEN
Schistosomiasis, a neglected tropical disease caused by trematodes of the Schistosoma genus, affects over 250 million people around the world. This disease has been associated with learning and memory deficits in children, whereas reduced attention levels, impaired work capacity, and cognitive deficits have been observed in adults. Strongly correlated with poverty and lack of basic sanitary conditions, this chronic endemic infection is common in Africa, South America, and parts of Asia and contributes to inhibition of social development and low quality of life in affected areas. Nonetheless, studies on the mechanisms involved in the neurological impairment caused by schistosomiasis are scarce. Here, we used a murine model of infection with Schistosoma mansoni in which parasites do not invade the central nervous system to evaluate the consequences of systemic infection on neurologic function. We observed that systemic infection with S. mansoni led to astrocyte and microglia activation, expression of oxidative stress-induced transcription factor Nrf2, oxidative damage, Tau phosphorylation, and amyloid-ß peptide accumulation in the prefrontal cortex of infected animals. We also found impairment in spatial learning and memory as evaluated by the Morris water maze task. Administration of anthelmintic (praziquantel) and antioxidant (N-acetylcysteine plus deferoxamine) treatments was effective in inhibiting most of these phenotypes, and the combination of both treatments had a synergistic effect to prevent such changes. These data demonstrate new perspectives toward the understanding of the pathology and possible therapeutic approaches to counteract long-term effects of systemic schistosomiasis on brain function.