Koh_2017_Int.J.Mol.Sci_18_

Spirulina maxima, a microalga containing high levels of protein and many polyphenols, including chlorophyll a and C-phycocyanin, has antioxidant and anti-inflammatory therapeutic effects. However, the mechanisms where by Spirulina maxima ameliorates cognitive disorders induced by amyloid-beta 1-42 (Abeta1-42) are not fully understood. In this study, we investigated whether a 70% ethanol extract of Spirulina maxima (SM70EE) ameliorated cognitive impairments induced by an intracerebroventricular injection of Abeta1-42 in mice. SM70EE increased the step-through latency time in the passive avoidance test and decreased the escape latency time in the Morris water maze test in Abeta1-42-injected mice. SM70EE reduced hippocampal Abeta1-42 levels and inhibited amyloid precursor protein processing-associated factors in Abeta1-42-injected mice. Additionally, acetylcholinesterase activity was suppressed by SM70EE in Abeta1-42-injected mice. Hippocampal glutathione levels were examined to determine the effects of SM70EE on oxidative stress in Abeta1-42-injected mice. SM70EE increased the levels of glutathione and its associated factors that were reduced in Abeta1-42-injected mice. SM70EE also promoted activation of the brain-derived neurotrophic factor/phosphatidylinositol-3 kinase/serine/threonine protein kinase signaling pathway and inhibited glycogen synthase kinase-3beta phosphorylation. These findings suggested that SM70EE ameliorated Abeta1-42-induced cognitive impairments by inhibiting the increased phosphorylation of glycogen synthase kinase-3beta caused by intracerebroventricular injection of Abeta1-42 in mice.