RhoA/Rock2/Limk1/cofilin1 pathway is involved in attenuation of neuronal dendritic spine loss by paeonol in the frontal cortex of D-galactose and aluminum­induced Alzheimer's disease­like rat model.

Alzheimer's disease (AD) has become the most prevalent neurodegenerative disorder. Given the pathogenesis of AD is unclear, there is currently no drug approved to halt or delay the progression of AD. Therefore, it is pressing to explore new targets and drugs for AD. In China, polyphenolic Chinese herbal medicine has been used for thousands of years in clinical application, and no toxic effects have been reported. In the present study, using D­galactose and aluminum­induced rat model, the effects of paeonol on AD were validated via the Morris water maze test, open field test, and elevated plus maze test. Neuronal morphology in frontal cortex was assessed using ImageJ's Sholl plugin and RESCONSTRUCT software. RhoA/Rock2/Limk1/cofilin1 signaling pathway­related molecules were determined by Western blotting. Cofilin1 and p­cofilin1 were analyzed by immunofluorescence. Results showed that pre­treatment with paeonol attenuated D­galactose and aluminum­induced behavioral dysfunction and AD­like pathological alterations in the frontal cortex. Accompanied by these changes were the alterations in the dendrite and dendritic spine densities, especially the mushroom­type and filopodia­type spines in the apical dendrites, as well as actin filaments. In addition, the activity and intracellular distribution of cofilin1 and the molecules RhoA/Rock2/Limk1 that regulate the signaling pathway for cofilin1 phosphorylation have also changed. Our data suggests that paeonol may be through reducing Aß levels to alleviate the loss of fibrillar actin and dendrites and dendritic spines via the Rho/Rock2/Limk1/cofilin1 signaling pathway in the frontal cortex, and ultimately improving AD­like behavior.

Effect of omega-3 polyunsaturated fatty acids on the cytoskeleton: an open-label intervention study.

BACKGROUND: Omega-3 polyunsaturated fatty acids (n-3 PUFAs) show beneficial effects on cardiovascular health and cognitive functions, but the underlying molecular mechanisms are not completely understood. Because of the fact that cytoskeleton dynamics affect almost every cellular process, the regulation of cytoskeletal dynamics could be a new pathway by which n-3 PUFAs exert their effects on cellular level. METHODS: A 12-week open-label intervention study with 12 healthy men was conducted to determine the effects of 2.7 g/d n-3 PUFA on changes in mRNA expression of cytoskeleton-associated genes by quantitative real-time PCR in whole blood. Furthermore, the actin content in red blood cells was analyzed by immunofluorescence imaging. RESULTS: N-3 PUFA supplementation resulted in a significant down-regulation of cytoskeleton-associated genes, in particular three GTPases (RAC1, RHOA, CDC42), three kinases (ROCK1, PAK2, LIMK), two Wiskott-Aldrich syndrome proteins (WASL, WASF2) as well as actin related protein 2/3 complex (ARPC2, ARPC3) and cofilin (CFL1). Variability in F-actin content between subjects was high; reduced actin content was only reduced within group evaluation. CONCLUSIONS: Reduced cytoskeleton-associated gene expression after n-3 PUFA supplementation suggests that regulation of cytoskeleton dynamics might be an additional way by which n-3 PUFAs exert their cellular effects. Concerning F-actin, this analysis did not reveal unmistakable results impeding a generalized conclusion.