RESUMEN
Objective: To investigate the effects of lycopene-loaded microemulsion (LME) on the cognitive function and neurogenesis in the dentate gyrus (DG) of the hippocampus and subventricular (SVZ) region of rats with amyloid ß- (Aß-) induced Alzheimer's disease (AD) and its mechanism based on the Wnt/ß-catenin pathway. Methods: Healthy Wistar rats were divided into four groups: the blank control (CON), AD control, traditional lycopene (LOO), and LME groups. The CON and AD groups were fed with normal saline, while the LOO group was fed with traditional lycopene, and the LME group was fed with lycopene-loaded microemulsion. Behavioral tests were performed after three weeks of gastric administration. Immunofluorescence-labeled cells were used to observe the differentiation and maturation of new nerve cells in the DG of the hippocampus and SVZ region. qRT-PCR and Western blotting detected the expression of neurogenesis genes and Wnt/ß-catenin pathway-related proteins, respectively. Results: On the Morris water maze test, LME rats had significantly shortened movement trajectory on the searching platform, reduced escape latency time, and increased residence time on the original platform quadrant. In addition, more LME rats crossed the platform when it was removed. Thus, LME can improve the spatial learning and memory of Aß-induced AD rats. On qRT-PCR, LME significantly increased Reelin, Nestin, and Pax6 gene expressions, which regulate neurogenesis. Immunofluorescence showed that LME could significantly increase BrdU+, Dcx+, BrdU+/Neun+, BrdU+/Dcx+ cells in the DG and SVZ regions, thus promoting neurogenesis. LME also reduced the number of Iba1+ and Iba1+/BrdU+ cells, thus reducing the neuroinflammatory response. On Western blot, LME upregulated the Wnt/ß-catenin pathway by upregulating Wnt3a, ß-catenin, Disheveled (Dvl), and p-GSK3ß and downregulating p-ß-catenin and GSK3ß. Conclusion: LME attenuates cognitive impairment in Aß-induced AD rats by promoting neurogenesis in the hippocampus and SVZ region through upregulating the Wnt/ß-catenin pathway.
Asunto(s)
Enfermedad de Alzheimer/inducido químicamente , Enfermedad de Alzheimer/tratamiento farmacológico , Péptidos beta-Amiloides/toxicidad , Licopeno/administración & dosificación , Neurogénesis/efectos de los fármacos , Fragmentos de Péptidos/toxicidad , Vía de Señalización Wnt/efectos de los fármacos , Enfermedad de Alzheimer/fisiopatología , Animales , Antioxidantes/administración & dosificación , Emulsiones , Hipocampo/citología , Hipocampo/efectos de los fármacos , Hipocampo/fisiología , Ventrículos Laterales/efectos de los fármacos , Masculino , Neurogénesis/fisiología , Ratas , Ratas Wistar , Vía de Señalización Wnt/fisiologíaRESUMEN
Advanced glycation endproducts (AGEs) are elevated in aging and neurodegenerative diseases such as Alzheimer's disease (AD), and they can stimulate the generation of reactive oxygen species (ROSs) via NADPH oxidase, induce oxidative stress that lead to cell death. In the current study, we investigated the molecular events underlying the process that AGEs induce cell death in SH-SY5Y cells and rat cortical neurons. We found: (1) AGEs increase intracellular ROSs; (2) AGEs cause cell death after ROSs increase; (3) oxidative stress-induced cell death is inhibited via the blockage of AGEs receptor (RAGE), the down-regulation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, and the increase of scavenging by anti-oxidant alpha-lipoic acid (ALA); (4) endoplasmic reticulum (ER) stress was triggered by AGE-induced oxidative stress, resulting in the activation of C/EBP homologous protein (CHOP) and caspase-12 that consequently initiates cell death, taurine-conjugated ursodeoxycholic acid (TUDCA) inhibited AGE-induced ER stress and cell death. Blocking RAGE-NADPH oxidase, and RAGE-NADPH oxidase-ROSs and ER stress scavenging pathways could efficiently prevent the oxidative and ER stresses, and consequently inhibited cell death. Our results suggest a new prevention and or therapeutic approach in AGE-induced cell death.