Alzheimer's disease (AD) is an aging-related multi-factorial disorder to which metabolic factors contribute at what has canonically been considered a centrally mediated process. Although the exact underlying mechanisms are still unknown, obesity is recognized as a risk factor for AD and the condition of insulin resistance seems to be the link between the two pathologies. Using mice with high fat diet (HFD) obesity we dissected the molecular mechanisms shared by the two disorders. Brains of HFD fed mice showed elevated levels of APP and Aβ 40 /Aβ 42 together with BACE, GSK3β and Tau proteins involved in APP processing and Aβ accumulation. Immunofluorescence, Thioflavin T staining experiments, confirmed increased Aβ generation, deposition in insoluble fraction and plaques formation in both the hippocampus and the cerebral cortex of HFD mice. Presence of Aβ 40 and Aβ 42 in the insoluble fraction was also shown by ELISA assay. Brain insulin resistance was demonstrated by reduced presence of insulin receptor (IRs) and defects in Akt-Foxo3a insulin signaling. We found reduced levels of phospho-Akt and increased levels of Foxo3a in the nuclei of neurons where proapototic genes were activated. Dysregulation of different genes related to insulin resistance, especially those involved in inflammation and adipocytokines synthesis were analyzed by Profiler PCR array. Further, HFD induced oxidative stress, mitochondrial dysfunction and dynamics as demonstrated by expression of biomarkers involved in these processes. Here, we provide evidence that obesity and AD markers besides insulin resistance are associated with inflammation, adipokine dyshomeostasis, oxidative stress and mitochondrial dysfunction, all mechanisms leading to neurodegeneration.

Mitochondria are dynamic ATP-generating organelle which contribute to many cellular functions including bioenergetics processes, intracellular calcium regulation, alteration of reduction-oxidation potential of cells, free radical scavenging, and activation of caspase mediated cell death. Mitochondrial functions can be negatively affected by amyloid β peptide (Aβ), an important component in Alzheimer's disease (AD) pathogenesis, and Aβ can interact with mitochondria and cause mitochondrial dysfunction. One of the most accepted hypotheses for AD onset implicates that mitochondrial dysfunction and oxidative stress are one of the primary events in the insurgence of the pathology. Here, we examine structural and functional mitochondrial changes in presence of Aβ. In particular we review data concerning Aβ import into mitochondrion and its involvement in mitochondrial oxidative stress, bioenergetics, biogenesis, trafficking, mitochondrial permeability transition pore (mPTP) formation, and mitochondrial protein interaction. Moreover, the development of AD therapy targeting mitochondria is also discussed.

Clinical and experimental biomedical studies have shown Type 2 diabetes mellitus (T2DM) to be a risk factor for the development of Alzheimer's disease (AD). This study demonstrates the effect of metformin, a therapeutic biguanide administered for T2DM therapy, on β-amyloid precursor protein (APP) metabolism in in vitro, ex vivo and in vivo models. Furthermore, the protective role of insulin against metformin is also demonstrated. In LAN5 neuroblastoma cells, metformin increases APP and presenilin levels, proteins involved in AD. Overexpression of APP and presenilin 1 (Pres 1) increases APP cleavage and intracellular accumulation of β-amyloid peptide (Aβ), which, in turn, promotes aggregation of Aβ. In the experimental conditions utilized the drug causes oxidative stress, mitochondrial damage, decrease of Hexokinase-II levels and cytochrome C release, all of which lead to cell death. Several changes in oxidative stress-related genes following metformin treatment were detected by PCR arrays specific for the oxidative stress pathway. These effects of metformin were found to be antagonized by the addition of insulin, which reduced Aβ levels, oxidative stress, mitochondrial dysfunction and cell death. Similarly, antioxidant molecules, such as ferulic acid and curcumin, are able to revert metformin's effect. Comparable results were obtained using peripheral blood mononuclear cells. Finally, the involvement of NF-κB transcription factor in regulating APP and Pres 1 expression was investigated. Upon metformin treatment, NF-κB is activated and translocates from the cytoplasm to the nucleus, where it induces increased APP and Pres 1 transcription. The use of Bay11-7085 inhibitor suppressed the effect of metformin on APP and Pres 1 expression.

Abstract-Neurodegenerative diseases such as Alzheimer, Parkinson, amyotrophic lateral sclerosis, and Huntington are incurable and debilitating conditions that result in progressive death of the neurons. The definite diagnosis of a neurodegenerative disorder is disadvantaged by the difficulty in obtaining biopsies and thereby to validate the clinical diagnosis with pathological results. Biomarkers are valuable indicators for detecting different phases of a disease such as prevention, early onset, treatment, progression, and monitoring the effect of pharmacological responses to a therapeutic intervention. Inflammation occurs in neurodegenerative diseases, and identification and validation of molecules involved in this process could be a strategy for finding new biomarkers. The ideal inflammatory biomarker needs to be easily measurable, must be reproducible, not subject to wide variation in the population, and unaffected by external factors. Our review summarizes the most important inflammation biomarkers currently available, whose specificity could be utilized for identifying and monitoring distinctive phases of different neurodegenerative diseases.

The onset of Alzheimer disease (AD) is influenced by several risk factors comprising diabetes. Within this context, antidiabetic drugs, including metformin, are investigated for their effect on AD. We report that in the C57B6/J mice, metformin is delivered to the brain where activates AMP-activated kinase (AMPK), its molecular target. This drug affects the levels of β-secretase (BACE1) and β-amyloid precursor protein (APP), promoting processing and aggregation of β-amyloid (Aβ), mainly in the cortex region. Moreover, metformin induces mitochondrial dysfunction and cell death by affecting the level and conformation of Translocase of the Outer Membrane 40 (TOM40), voltage-dependent anion-selective channels 1 (VDAC1) and hexokinase I (HKI), proteins involved in mitochondrial transport of molecules, including Aβ. By using biophysical techniques we found that metformin is able to directly interact with Aβ influencing its aggregation kinetics and features. These findings indicate that metformin induces different adverse effects, leading to an overall increase of the risk of AD onset.

Neuroblastoma (NB) is one of the most frequent extracranial solid tumors in children. It accounts for 8-10% of all childhood cancer deaths, and there is a need for development of new drugs for its treatment. Curcumin (diferuloylmethane), a major active component of turmeric (Curcuma longa), has been shown to exert anti-tumor activity on NB, but the specific mechanism by which curcumin inhibits cancer cells proliferation remains unclear. In the present study, we investigated the anti-proliferative effect of curcumin in human LAN5 NB cells. Curcumin treatment causes a rapid increase in reactive oxygen species and a decrease in the mitochondrial membrane potential-events leading to apoptosis activation. Furthermore, curcumin induces decrease in haet shock protein (Hsp)60 and hexokinase II mitochondrial protein levels and increase in the pro-apoptotic protein, bcl-2 associated death promoter (BAD). Moreover, we demonstrate that curcumin modulates anti-tumor activity through modulation of phosphatase and tensin homolog deleted on chromosome 10 and consequential inhibition of the survival Akt cell-signaling pathway. Inhibition of Akt causes its translocation into the cytoplasm and import of Foxo3a into the nucleus where it activates the expression of p27, Bim, and Fas-L pro-apoptotic genes. Together, these results take evidence for considering curcumin as a potential therapeutic agent for patients with NB.

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The purpose of the present study was to evaluate the impact of long-term honey ingestion on metabolic disorders and neurodegeneration in mice fed a high-fat diet (HFD). Three groups of mice were fed with a standard diet (STD), HFD or HFD supplemented with honey (HFD-H) for 16 weeks. Biochemical, histological, Western blotting, RT-PCR and Profiler PCR array were performed to assess metabolic parameters, peripheral and central insulin resistance and neurodegeneration. Daily honey intake prevented the HFD-induced glucose dysmetabolism. In fact, it reduced plasma fasting glucose, insulin and leptin concentrations and increased adiponectin levels. It improved glucose tolerance, insulin sensitivity and HOMA index without affecting plasma lipid concentration. HFD mice showed a significantly higher number of apoptotic nuclei in the superficial and deep cerebral cortex, upregulation of Fas-L, Bim and P27 (neuronal pro-apoptotic markers) and downregulation of Bcl-2 and BDNF (anti-apoptotic factors) in comparison with STD- and HFD-H mice, providing evidence for honey neuroprotective effects. PCR-array analysis showed that long-term honey intake increased the expression of genes involved in insulin sensitivity and decreased genes involved in neuroinflammation or lipogenesis, suggesting improvement of central insulin resistance. The expressions of p-AKT and p-GSK3 in HFD-H mice, which were decreased and increased, respectively, in HFD mouse brain, index of central insulin resistance, were similar to STD animals supporting the ability of regular honey intake to protect brain neurons from insulin resistance. In conclusion, the present results provide evidence for the beneficial preventative impact of regular honey ingestion on neuronal damage caused by HFD.