3,4-dihydroxyphenylethanol attenuates spatio-cognitive deficits in an Alzheimer's disease mouse model: modulation of the molecular signals in neuronal survival-apoptotic programs.

Alzheimer's disease (AD), the most common type of dementia, is a devastating neurodegenerative disease characterized by progressive neuro-cognitive dysfunction. In our study, we investigated the potential of 3,4-dihydroxyphenylethanol (DOPET), a dopamine metabolite, and also a polyphenol from olive oil, in ameliorating soluble oligomeric amyloid β1-42 plus ibotenic acid (oA42i)-induced neuro-behavioral dysfunction in C57BL/6 mice. The results depicted that intracerebroventricular injection of oA42i negatively altered the spatial reference and working memories in mice, whereas DOPET treatment significantly augmented the spatio-cognitive abilities against oA42i. Upon investigation of the underlying mechanisms, oA42i-intoxicated mice displayed significantly activated death kinases including JNK- and p38-MAPKs with concomitantly inhibited ERK-MAPK/RSK2, PI3K/Akt1, and JAK2/STAT3 survival signaling pathways in the hippocampal neurons. Conversely, DOPET treatment reversed these dysregulated signaling mechanisms comparable to the sham-operated mice. Notably, oA42i administration altered the Bcl-2/Bad levels and activated the caspase-dependent mitochondria-mediated apoptotic pathway involving cytochrome c, apoptotic protease activating factor-1, and caspase-9/3. In contrary, DOPET administration stabilized the dysregulated activities of these apoptotic/anti-apoptotic markers and preserved the mitochondrial ultra-architecture. Besides, we observed that oA42i intoxication substantially down-regulated the expression of genes involved in the regulation of survival and memory functions including sirtuin-1, cyclic AMP response element-binding protein (CREB), CREB-target genes (BDNF, c-Fos, Nurr1, and Egr1) and a disintegrin and metalloprotease 10. Fascinatingly, DOPET treatment significantly diminished these aberrations when compared to the oA42i group. Taken together, these results accentuate that DOPET may be a multipotent agent to combat AD.