Chronic high fat feeding paradoxically attenuates cerebral capillary dysfunction and neurovascular inflammation in Senescence-Accelerated-Murine-Prone Strain 8 mice

Are fat and sugar just as detrimental in old age?

Aging and poor nutrition are independent risk factors for the development of chronic disease. When young animals are given diets high in fat or sugar, they exhibit hallmarks of aging like mitochondrial dysfunction and inflammation, and also develop a greater risk for age-related disease. The same mitochondrial dysfunction and inflammation that progress with aging may also further predispose older individuals to dietary insults by fat and sugar. The purpose of this work is to review the most recent studies that address the impact of fat and sugar consumption on hallmarks of aging (mitochondrial dysfunction and inflammation). Findings from these studies show that obesogenic, high-fat diets can exacerbate age-related disease and hallmarks of aging in young animals, but high-fat diets that are non-obesogenic may play a beneficial role in old age. In contrast, high-sugar diets do not require an obesogenic effect to induce mitochondrial dysfunction or inflammation in young rodents. Currently, there is a lack of experimental studies addressing the impact of sugar in the context of aging, even though empirical evidence points to the detrimental effect of sugar in aging by contributing to a variety of age-related diseases. Fig. 1 Mitochondrial dysfunction and altered cellular communication (e.g. inflammation) progress with advancing age and increase the risk for age-related disease (ARD). Given the physiological changes that occur with age, the impact of high-fat (HFD) and high-sugar diets (HSD) may differ in later and earlier stages of life. HFD can promote the development of hallmarks of aging in young animals and can also exacerbate the risk for ARD when consumed at an old age. However, non-obesogenic high-fat diets may also reduce the risk for ARD in old age by acting on these hallmarks of aging. On the other hand, HSD promotes mitochondrial dysfunction and inflammation without necessarily inducing weight gain in young animals. Empirical evidence points to sugar as a major contributor to age-related disease and more experimental studies are needed to clarify whether aged individuals are more susceptible to its effects.

[Mapping the Metallo-maze to Memory Loss: Does Neuronal Metal Ion Deficiency Contribute to Dementia?]

Dementia has no cure and is an international health crisis. In addition to the immeasurable loss of QOL caused by dementia, the global economic cost is predicted to reach $2 trillion (USD) by 2030. Although much remains unknown about the biochemical pathways driving cognitive decline and memory loss during dementia, metals have been implicated in neurodegenerative disease. For example, total levels of Fe and Cu increase, which has been proposed to drive oxidative stress; and Fe, Cu, and Zn can bind amyloid-β, catalysing aggregation and formation of amyloid plaques. Unfortunately, despite these known facets through which metal ions may induce pathology, studies in greater detail have been hampered by a lack of microscopy methods to directly visualise metal ions, and their chemical form, within brain cells. Herein we report the use of synchrotron X-ray fluorescence microscopy to simultaneously image Fe, Cu, and Zn within neurons in ex vivo brain tissue sections. Using animal models of dementia, we now demonstrate for the first time that despite global increases in brain metal content and metal ion accumulation within amyloid plaques, key brain regions may also become metal ion deficient. Such deficiency could contribute to cognitive decline because of the essential roles metal ions play in neurotransmitter synthesis and energy metabolism. These recent findings are discussed in the context of memory loss, and the impact that metal ion dis-homeostasis may have on diagnostic and therapeutic development.

Zerumbone augments cognitive enhancement potentials of EPA+DHA: insight from a hyperlipidaemic rat model

Hyperlipidaemia and cognitive dysfunction (CD) are the two public health concerns. Though hyperlipidaemia has been comprehensively studied in respect to CVD, its role on CD needs to be explored. Hence, we evaluated hyperlipidaemia as a risk factor for CD and the efficacy of EPA (20 : 5n-3) + DHA (22 : 6n-3) and zerumbone (Z) in modulating CD under hyperlipidaemic conditions. Male Wistar rats (Rattus norvegicus) were fed control, high-fat (HF), high-fat + fish oil (HF + F), high-fat + zerumbone (HF+Z) and high-fat + fish oil + zerumbone (HF+F+Z) containing diets. After a 30 d feeding trial, memory parameters (Morris water maze, elevated plus maze (transfer latency) and T-maze (spontaneous alteration)) and locomotor skills (open field test and rotarod test) were assessed. Hyperlipidaemia significantly (P < 0·05) reduced memory and motor coordination skills compared with control. However, the administration of EPA + DHA and zerumbone significantly (P < 0·05) restored the hyperlipidaemia-induced loss of memory and motor coordination skills. Collectively, our data imply that hyperlipidaemia causes CD by decreasing memory and motor coordination skills, and administration of EPA + DHA and zerumbone prevents hyperlipidaemia-induced CD. The augmented effect of EPA + DHA, together with zerumbone, discloses a promising strategy for lowering the severity of CD in hyperlipidaemic conditions.