Entry #: 2
Date: 29 June 2017
Topic: Extra-virgin olive oil and Alzheimer’s disease
Type: Original Paper
OliveNetTM Journal Club
Expert review of literature related to olives and olive oil
D. Elizabeth McCord, Nancy B. Ray and Tom C. Karagiannis
Extra-virgin olive oil ameliorates cognition and neuropathology of the 3xTg mice: role of autophagy
Lauretti E, Luliano L, and Pratico D.
Annals of Clinical and Translational Neurology, DOI: 10.1002/acn3.431, 21 June 2017
Extra-virgin olive oil, Mediterranean diet, Alzheimer’s disease, amyloid-beta, amyloid plaques, tau fibrils, neurofibrillary tangles
Accumulating epidemiological and clinical evidence has highlighted the beneficial effects of the Mediterranean diet in cognitive disorders including Alzheimer’s disease. Many studies indicate that extra-virgin olive oil (including molecular studies with individual phenolic constituents), is at least in part, responsible for the beneficial effects of the Mediterranean diet. The overall aim of this study was to evaluate the effects of prolonged (6 month) feeding of extra-virgin olive oil in a transgenic mouse model displaying features of Alzheimer’s disease. The study represents an extension to previous work which had indicated improved learning and memory (1), attenuated age-related dysfunctions including behaviour, motor coordination and contextual memory (2, 3), and mitigated amyloid-β and tau pathologies in mouse models (4). In this work, a triple transgenic (presenilin 1 [PS1M146V], tauP301L, amyloid precursor protein [APPSwe]) mouse model was utilised. The advantage of this model is that both of the major Alzheimer’s disease hallmarks namely, amyloid plaques and tau neurofibrillary tangle, are displayed (5). The major findings indicated attenuation of behavioural and cellular features associated with the Alzheimer’s disease phenotype in mice fed a regular diet supplemented with extra-virgin olive oil compared to control mice.
Key points and implications
The authors utilised well-established memory and behavioural models to investigate deficits in AD mice and potential improvements in mice fed a diet supplemented with extra-virgin olive oil. Overall, the findings indicated subtle (significant improvement in spatial memory and learning as suggested by the results of the Morris water maze test), improvements in behavioural changes attributed to the consumption of extra-virgin olive oil. It is interesting to note, a trend towards (significant at 10 months [4 months on modified diet]) an increase in weight in mice that consumed the diet supplemented with extra virgin olive oil compared to control mice. Western blot and histological analyses indicated significant reductions in amyloid-β levels and deposition in the brain, attenuated tau neuropathology and improved synaptic integrity and neuroinflammation (synaptophysin and Iba-1) in mice that consumed that extra-virgin olive oil supplemented diet. To further clarify the mechanism, it was shown that the effects of supplementation with extra-virgin olive oil were not due to cAMP response element-binding protein (CREB) signalling (CREB and CREB-regulated proteins have been implicated in cognitive disorders [including Alzheimer’s disease] and aging). The autophagy protein 5 and related protein (Atg) 7 were both significantly increased in the mice that consumed extra virgin olive oil compared to control mice. This suggests activation of autophagy (degradative process involving vesicle-mediated shuttling and clearance of mis-folded proteins or damaged proteins or organelles via lysosomes), is an underlying cellular mechanism accounting for beneficial effects observed with extra-virgin olive oil.
- S. A. Farr et al., Extra virgin olive oil improves learning and memory in SAMP8 mice. J Alzheimers Dis 28, 81-92 (2012).
- V. Pitozzi et al., Effects of dietary extra-virgin olive oil on behaviour and brain biochemical parameters in ageing rats. Br J Nutr 103, 1674-1683 (2010).
- V. Pitozzi et al., Long-term dietary extra-virgin olive oil rich in polyphenols reverses age-related dysfunctions in motor coordination and contextual memory in mice: role of oxidative stress. Rejuvenation Res 15, 601-612 (2012).
- H. Qosa et al., Extra-virgin olive oil attenuates amyloid-beta and tau pathologies in the brains of TgSwDI mice. J Nutr Biochem 26, 1479-1490 (2015).
- S. Oddo et al., Triple-transgenic model of Alzheimer’s disease with plaques and tangles: intracellular Abeta and synaptic dysfunction. Neuron 39, 409-421 (2003).
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