Reduction in Hippocampal Amyloid-ß Peptide (Aß) Content during Glycine-Proline-Glutamate (Gly-Pro-Glu) Co-Administration Is Associated with Changes in Inflammation and Insulin-like Growth Factor (IGF)-I Signaling.

Alzheimer's disease (AD) is characterized by the deposition in the brain of senile plaques composed of amyloid-ß peptides (Aßs) that increase inflammation. An endogenous peptide derived from the insulin-like growth factor (IGF)-I, glycine-proline-glutamate (GPE), has IGF-I-sensitizing and neuroprotective actions. Here, we examined the effects of GPE on Aß levels and hippocampal inflammation generated by the intracerebroventricular infusion of Aß25-35 for 2 weeks (300 pmol/day) in ovariectomized rats and the signaling-related pathways and levels of Aß-degrading enzymes associated with these GPE-related effects. GPE prevented the Aß-induced increase in the phosphorylation of p38 mitogen-activated protein kinase and the reduction in activation of signal transducer and activator of transcription 3, insulin receptor substrate-1, and Akt, as well as on interleukin (IL)-2 and IL-13 levels in the hippocampus. The functionality of somatostatin, measured as the percentage of inhibition of adenylate cyclase activity and the levels of insulin-degrading enzyme, was also preserved by GPE co-treatment. These findings indicate that GPE co-administration may protect from Aß insult by changing hippocampal cytokine content and somatostatin functionality through regulation of leptin- and IGF-I-signaling pathways that could influence the reduction in Aß levels through modulation of levels and/or activity of Aß proteases.

Olive oil and wine as source of multi-target agents in the prevention of Alzheimer disease.

Olive oil and wine are consumed daily worldwide, and they constitute the fundamental pillars of the healthy Mediterranean diet. Polyphenolic compounds, naturally present in both olive oil and wine, are responsible for their beneficial properties. Current studies have shown the neuroprotective effects of polyphenols independently of their well-known antioxidant action. In this work, we have focused on reviewing the protective effect of polyphenols from extra virgin olive oil and wine in Alzheimer´s disease (AD), to emphasise that both foods could be a possible therapeutic tool. Beneficial effects have been described in ß-aggregation, neurofibrillary tangles, autophagy and mitochondrial function, as well as in cerebral insulin resistance. Furthermore, to date, a harmful dose has not been described. Both pre-clinical and clinical works demonstrate that polyphenols act on neuropathological and cognitive disorders of AD, preventing or stopping the onset of this devastating disease. However, there are certain limitations in these studies, since it is very difficult to research diseases that lead to cognitive impairment. Although all the findings obtained are very encouraging, more studies should be carried out investigating the use of the polyphenols from olive oil and wine as therapeutic agents in the progression of AD. Therefore, more longitudinal studies in humans with a homogeneous cohort of patients are necessary to corroborate the efficacy of these nutraceuticals, as well as determine the most appropriate dose for this purpose.

SLAMF1 is expressed and secreted by hepatocytes and the liver in nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent forms of chronic liver disease in the United States and worldwide. Nonalcoholic steatohepatitis (NASH), the most advanced form of NAFLD, is characterized by hepatic steatosis associated with inflammation and hepatocyte death. No treatments are currently available for NASH other than lifestyle changes, and the disease lacks specific biomarkers. The signaling lymphocytic activation molecule family 1 (SLAMF1) protein is a self-ligand receptor that plays a role in orchestrating an immune response to some pathogens and cancers. We found that livers from humans and mice with NASH showed a more prominent immunohistochemistry staining for SLAMF1 than non-NASH controls. Furthermore, SLAMF1 levels are significantly increased in NASH plasma samples from mice and humans compared with their respective controls. In mice, the levels of SLAMF1 correlated significantly with the severity of the NASH phenotype. To test whether SLAMF 1 is expressed by hepatocytes, HepG2 cells and primary murine hepatocytes were treated with palmitic acid (PA) to induce a state of lipotoxicity mimicking NASH. We found that PA treatments of HepG2 cells and primary hepatocytes lead to significant increases in SLAMF1 levels. The downregulation of SLAMF1 in HepG2 cells improved the cell viability and reduced cytotoxicity. The in vivo data using mouse and human NASH samples suggests a potential role for this protein as a noninvasive biomarker for NASH. The in vitro data suggest a role for SLAMF1 as a potential therapeutic target to prevent hepatocyte death in response to lipotoxicity.NEW & NOTEWORTHY This study identified for the first time SLAMF1 as a mediator of hepatocyte death in nonalcoholic fatty liver disease (NASH) and as a marker of NASH in humans. There are no pharmacological treatments available for NASH, and diagnostic tools are limited to invasive liver biopsies. Therefore, since SLAMF1 levels correlate with disease progression and SLAMF1 mediates cytotoxic effects, this protein can be used as a therapeutic target and a clinical biomarker of NASH.

Hydroxytyrosol improves mitochondrial energetics of a cellular model of Alzheimer's disease.

Mitochondrial energetic deficit is one of the hallmarks of neurodegenerative disorders, e.g. Alzheimer´s disease (AD). Adherence to a Mediterranean diet is associated with lower incidence of cognitive decline and AD and extra virgin olive oil's (poly)phenols such as oleuropein and hydroxytyrosol (HT) are being actively studied in this respect. In this study, we assessed the effects of HT on mitochondrial energetic dysfunction in the 7PA2 cells cellular model, i.e. one of the best cellular models of Aß toxicity with a well-characterized mitochondrial dysfunction typically observed in AD. We report an increase of new mitochondria at 8 h post HT-treatment, which was followed by higher mitochondrial fusion. Further, ATP concentrations were significantly increased after 24 h of treatment with HT as compared with controls. Our data suggest that HT may revert the energetic deficit of a cellular model of AD by potentiating mitochondrial activity. Because HT is being proposed as dietary supplement or component of functional foods, future studies in appropriate animal models and - eventually - humans are warranted to further investigate its potential neuroprotective actions in AD.

One-week administration of hydroxytyrosol to humans does not activate Phase II enzymes.

The notion that (poly)phenols act as direct free radical scavengers is being challenged by mere chemical and biochemical considerations such as bioavailability and intracellular concentrations. An alternative hypothesis that is gaining considerable traction is that (poly)phenols are processed by the body as xenobiotics via the Keap1/Nrf2/ARE signaling axis, leading to the induction of Phase II enzymes. However, there are no solid human data to confirm this interesting supposition. In this study, we tested the activities of hydroxytyrosol (HT) on Phase II enzymes' expression in a double-blind, randomized, placebo-controlled study. We tested two HT doses, i.e. 5 and 25mg/d, vs. placebo following a Latin square design. We report that HT is well tolerated but does not significantly modify Phase II enzyme expression in peripheral blood mononuclear cells. Moreover, we were unable to record significant effects on a variety of surrogate markers of cardiovascular disease such as lipid profile and inflammation and oxidation markers. Available evidence indicates that the "hormesis hypothesis" that (poly)phenols activate Phase II enzymes requires solid human confirmation that might be provided by future trials. This study is registered at ClinicalTrials.gov (identifier: NCT02273622).

Olive Oil Components as Novel Antioxidants in Neuroblastoma Treatment: Exploring the Therapeutic Potential of Oleuropein and Hydroxytyrosol.

In this review, we explored the therapeutic potential of oleuropein (OLE) and hydroxytyrosol (HT) in the treatment of neuroblastoma (NB). NB is an extracranial tumour that predominantly affects children aged between 17 and 18 months. Recurrence and drug resistance have emerged as the biggest challenges when treating NB, leading to a crucial need for new therapeutic approaches. Food of the Mediterranean Diet (MD) presents several health benefits, including that of cancer treatment. In this review, we emphasised olive oil since it is one of the main liquid ingredients of the MD. OLE is the principal phenolic compound that constitutes olive oil and is hydrolysed to produce HT. Considering that tumour cells produce increased amounts of reactive oxygen species, this review highlights the antioxidant properties of OLE and HT and how they could result in increased cellular antioxidant defences and reduced oxidative damage in NB cells. Moreover, we highlight that these phenolic compounds lead to apoptosis and cell cycle arrest, reduce the side effects caused by conventional treatments, and activate tumours that become dormant as a resistance mechanism. Future research should explore the effects of these compounds and other antioxidants on the treatment of NB in vivo.

Dietary plant microRNAs as potential regulators of cellular cholesterol efflux.

AIM: Epidemiological evidence suggests adherence to vegetable-rich diets is associated to atheroprotective effects and bioactive components are most likely to play a relevant role. The notion of inter-kingdom regulation has opened a new research paradigm and perhaps microRNAs (miRNAs) from edible vegetables could influence consumer gene expression and lead to biological effects. We aimed to investigate the potential impact of broccoli-derived miRNAs on cellular cholesterol efflux in vitro. METHODS: Four miRNAs (miR159a, miR159b, miR166a and miR403) from Brassica oleracea var. italica (broccoli), a widely consumed cruciferous vegetable, were selected for further investigation, based on their high abundancy in this vegetable and their presence in other plants. Selected miRNAs were synthesized with a 3'-terminal 2'-O-methylation and their cellular toxicity, in vitro gastrointestinal resistance and cellular uptake were evaluated. Potential target genes within the mammalian transcriptome were assessed in silico following pathway analysis. In vitro cholesterol efflux was assessed in human THP-1-derived macrophages. RESULTS: miRNAs survival to in vitro GI digestion was around 1%, although some variation was seen between the four candidates. Cellular uptake by mammalian cells was confirmed, and an increase in cholesterol efflux was observed. Pathway analysis suggested these miRNAs are involved in biological processes related to phosphorylation, phosphatidylinositol and Wnt signaling, and to the insulin/IGF pathway. CONCLUSIONS: Health-promoting properties attributed to cruciferous vegetables, might be mediated (at least in part) through miRNA-related mechanisms.

Zebrafish Model Insights into Mediterranean Diet Liquids: Olive Oil and Wine.

In this review, we explored the potential of a zebrafish model to investigate the antioxidant effects of key components of the Mediterranean diet, namely, olive oil and wine, in the context of preventing age-related diseases, particularly cardiovascular conditions. This paper explores the spectrum of observational studies to preclinical investigations and ultimately converges toward potential translational insights derived from animal experimentation. This review highlights the potential and underutilization of zebrafish as an experimental model in this domain. We highlighted the genetic proximity of zebrafish to humans, offering a unique opportunity for translational insights into the health benefits of olive oil and wine. Indeed, we wanted to focus on the potential of zebrafish to elucidate the health benefits of olive oil and wine while calling for continued exploration to unlock its full potential to advance our knowledge of age-related disease prevention within the Mediterranean diet framework.

Is hydrogen peroxide an effective mouthwash for reducing the viral load of SARS-CoV-2 in dental clinics?

BACKGROUND: Previous studies have demonstrated that SARS-CoV-2 is mainly transmitted by inhalation of aerosols and can remain viable in the air for hours. Viruses can spread in dental settings and put professionals and patients at high risk of infection due to proximity and aerosol-generating procedures, and poor air ventilation. OBJECTIVES: The aim of this study was to investigate the effects of a 1% hydrogen peroxide (H2O2) mouth rinse on reducing the intraoral SARS-CoV-2 load. METHODS: Portable air cleaners with HEPA filters exposed for 3 months were analysed to test for virus presence in a waiting room (where patients wore a face mask but did not undergo mouth rinsing) and three treatment rooms (where patients wore no mask but carried out mouth rinsing). As CO2 is co-exhaled with aerosols containing SARS-CoV-2 by COVID-19 infected people, we also measured CO2 as a proxy of infection risk indoors. Specific primer and probe RT-PCR were applied to detect viral genomes of the SARS-CoV-2 virus in the filters. Specifically, we amplified the nucleocapsid gene (Nuclv) of SARS-CoV-2. RESULTS: CO2 levels ranged from 860 to 907 ppm, thus indicating low ventilation and the risk of COVID-19 transmission. However, we only found viral load in filters from the waiting room and not from the treatment rooms. The results revealed the efficiency of 1-minute mouth rinsing with 1% H2O2 since patients rinsed their mouths immediately after removing their mask in the treatment rooms. CONCLUSIONS: Our findings suggest that dental clinics would be safer and more COVID-19 free by implementing mouth rinsing 1 min with 1% H2O2 immediately after the patients arrive at the clinic.

Chronic central leptin infusion modifies the response to acute central insulin injection by reducing the interaction of the insulin receptor with IRS2 and increasing its association with SOCS3.

Leptin and insulin have overlapping intracellular signaling mechanisms and exert anorexigenic actions in the hypothalamus. We aimed to determine how chronic exposure to increased leptin affects the hypothalamic response to a rise in insulin. We analyzed the activation and interactions of components of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in the hypothalamus of rats treated icv for 14 days with leptin followed by a central injection of insulin and killed 15 min later. Insulin increased glycemia and chronic leptin reduced this insulin induced rise in glucose. Leptin decreased the association between the insulin receptor beta chain (IRß) and insulin receptor substrate 2 (IRS2), augmented the association between Janus kinase 2 and IRS2, increased levels of the catalytic subunit of PI3K and pAkt-Ser473 and decreased forkhead box O number 1 levels. Insulin reduced the association between suppressor of the cytokine signaling 3 and IRß, increased IRß-IRS2 association and pAkt-Thr308 levels, with chronic leptin exposure blunting these effects. In conclusion, chronic exposure to leptin decreases the central response to insulin by increasing suppressor of the cytokine signaling 3 association to IR, which inhibits insulin signaling at the level of interaction of its receptor with IRS2 and activates PI3K by promoting Janus kinase 2-IRS2 association. Thus, these results suggest that this mechanism could be a target for the treatment of insulin resistance.

Cerebral Insulin Bolus Revokes the Changes in Hepatic Lipid Metabolism Induced by Chronic Central Leptin Infusion.

Central actions of leptin and insulin on hepatic lipid metabolism can be opposing and the mechanism underlying this phenomenon remains unclear. Both hormones can modulate the central somatostatinergic system that has an inhibitory effect on growth hormone (GH) expression, which plays an important role in hepatic metabolism. Using a model of chronic central leptin infusion, we evaluated whether an increase in central leptin bioavailability modifies the serum lipid pattern through changes in hepatic lipid metabolism in male rats in response to an increase in central insulin and the possible involvement of the GH axis in these effects. We found a rise in serum GH in leptin plus insulin-treated rats, due to an increase in pituitary GH mRNA levels associated with lower hypothalamic somatostatin and pituitary somatostatin receptor-2 mRNA levels. An augment in hepatic lipolysis and a reduction in serum levels of non-esterified fatty acids (NEFA) and triglycerides were found in leptin-treated rats. These rats experienced a rise in lipogenic-related factors and normalization of serum levels of NEFA and triglycerides after insulin treatment. These results suggest that an increase in insulin in leptin-treated rats can act on the hepatic lipid metabolism through activation of the GH axis.

Evaluation of a multiplex assay for adipokine concentrations in obese children.

BACKGROUND: Multiplexed bead immunoassays allow simultaneous measurement of adipokines and other hormones in small serum samples, although a validation of this technique with classical methods has not been fully established. The purpose of this pilot study was to compare the characteristics of a multiplexed bead immunoassay obesity panel for insulin and various adipokines with classical methods. METHODS: A multiplexed bead immunoassay was performed using serum from 20 obese children at baseline and after reducing their body mass index, and in 25 controls. Insulin, adiponectin, leptin, resistin, tumor necrosis factor-α and interleukin-6 measured by multiplexed bead immunoassay were compared with results obtained from commercial immunoassays. Correlation, sensitivity, recovery, linearity, performance and imprecision were established for each analyte. RESULTS: The correlation between methods was acceptable for adiponectin, leptin, and insulin with coefficients of 0.75-0.89 (p<0.001). Correlation was weak for resistin (0.54, p<0.001) and poor (r<0.30) for tumor necrosis factor-α and interleukin-6. However, Bland-Altman analysis indicated agreement for insulin methods (bias=-0.07), avoiding direct comparison with other analytes (bias>1.25). The imprecision was similar for both methods (<13%). Multiplexed immunoassay had a broader dynamic range than classical methods (4.94 times). The magnitude of the changes in serum concentrations after weight loss was comparable with both methods for adiponectin, leptin, insulin and resistin, resulting in similar statistical significance. Changes in tumor necrosis factor-α and interleukin-6 were detected by classical immunoassays only (p<0.05). CONCLUSIONS: This study demonstrates that multiplexed bead immunoassay is more cost effective for measurement of adipokines present in relatively large amounts, diminishing inter-assay variations and reducing the sample volume.

Regional and temporal differences in leptin signaling in rat brain.

Leptin regulates energy homeostasis through activation of different hypothalamic pathways. Evidence indicates that leptin is a pleiotropic hormone that acts on many brain areas, altering food intake, metabolism, and locomotion, among other functions. Because short-term effects of leptin infusion and intracellular pathways in other brain areas involved in food regulation have not been thoroughly analysed, we have studied the acute effect of intracerebroventricular leptin administration on the levels of the long form of leptin receptor (Ob-Rb), as well as on activation of Janus kinase 2 (JAK2)-signal transducer and activator of transcription 3 (STAT3), protein kinase B (Akt), extracellular regulated kinases (ERKs) and levels of suppressor of cytokine signaling-3 (SOCS3) in the hypothalamus, hippocampus, frontal cortex and cerebellum of adult male Wistar rats at 15min, 1 and 6h. The levels of Ob-Rb increased at 6h in hypothalamus only. Leptin activated the JAK2/STAT3 pathway in all areas, although in a temporally specific pattern. In contrast, this hormone decreased Akt activation in hypothalamus, hippocampus and cerebellum and ERK activation in frontal cortex, while it increased ERK activation in hypothalamus and hippocampus. These differences in modulation of Ob-Rb levels and signaling indicate that the rapid effects of leptin in non-hypothalamic areas are mediated, at least in part, through the intracellular pathways involved in hypothalamic energy balance, but in a temporally specific manner.

Concentrates of buttermilk and krill oil improve cognition in aged rats.

Cognitive decline is one of the hallmarks of aging and can vary from mild cognitive impairment to dementia to Alzheimer's disease. In addition to some lifestyle interventions, there is room for the use of nutraceuticals/functional foods as pharma-nutritional tools to lessen the burden of cognitive decline before it worsens. We previously reported the promising molecular actions of milk fat globule membranes and krill oil concentrates in a rat model of aging. In this study, we concentrated on the activities on cognition, using an array of validated tests. We also performed lipidomic analyses of plasma, erythrocytes, and different brain areas. We report lower emotional memory (contextual fear conditioning) in aged rats supplemented with concentrates of polar lipids from buttermilk or krill oil at doses that approximate human consumption. No other behavioral parameter was significantly influenced by the supplements, calling for further research to confirm or not the purported salubrious activities of polar lipids, namely those rich in ω3 long-chain polyunsaturated fatty acids, on cognitive decline.

A nitric oxide synthase inhibitor, L-NAME, prevents L-arginine-induced downregulation of the rat cortical somatostatinergic system.

Activation of NMDA receptors leads to nitric oxide (NO) synthesis by NO synthase (NOS) from L-arginine. Neuronal NOS colocalizes with somatostatinergic (SRIF) neurons and there is growing evidence of an interaction between NO and the cerebral SRIFergic system in several neurological diseases. Our aim was to study the effect of L-arginine on the regulation of the SRIFergic system in the frontoparietal cortex of male Sprague-Dawley rats. Intraperitoneal administration of L-arginine (150 mg/Kg), twice-daily during eight days, induced a decrease in SRIF receptor density, which was accompanied by a reduction in the capacity of SRIF to stimulate inositol-1,4,5-triphosphate (IP3) accumulation and SRIF-like immunoreactivity (SRIF-LI) levels. To determine if these changes were related to L-arginine-derived NO synthesis, a NOS inhibitor, Nω-nitro-L-arginine methyl ester was coadministered with L-arginine. Its coadministration prevented the reduction in the SRIF receptor density, accumulation of IP3 and SRIF-LI content. These findings indicate that L-arginine induces a deleterious effect on the cortical somatostatinergic system and that the inhibition of NOS could be helpful in some neurological disorders where this neurotransmitter system is affected.

The N-terminal tripeptide of insulin-like growth factor-I protects against beta-amyloid-induced somatostatin depletion by calcium and glycogen synthase kinase 3 beta modulation.

The protective effects of insulin-like growth factor I on the somatostatin (SRIF) system in the temporal cortex after beta-amyloid (Abeta) injury may be mediated through its N-terminal tripeptide glycine-proline-glutamate (GPE). GPE is cleaved to cyclo[Pro-Gly] (cPG), a metabolite suggested to mediate in neuroprotective actions. We evaluated the effects of GPE and cPG in the temporal cortex of Abeta25-35-treated rats on SRIF and SRIF receptor protein and mRNA levels, adenylyl cyclase activity, cell death, Abeta25-35 accumulation, cytosolic calcium levels ([Ca(2+)](c)) and the intracellular signaling mechanisms involved. GPE and cPG did not change Abeta25-35 levels, but GPE partially restored SRIF and SRIF receptor 2 protein content and mRNA levels and protected against cell death after Abeta25-35 insult, which was coincident with Akt activation and glycogen synthase kinase 3beta inhibition. In addition, GPE displaced glutamate from NMDA receptors and blocked the glutamate induced rise in cytosolic calcium in isolated rat neurons and moderately increased Ca(2+) influx per se. Our findings suggest that GPE, but not its metabolite, mimics insulin-like growth factor I effects on the SRIF system through a mechanism independent of Abeta clearance that involves modulation of calcium and glycogen synthase kinase 3beta signaling.

The increase in fiber size in male rat gastrocnemius after chronic central leptin infusion is related to activation of insulin signaling.

Insulin potentiates leptin effects on muscle accrual and glucose homeostasis. However, the relationship between leptin's central effects on peripheral insulin sensitivity and the associated structural changes remain unclear. We hypothesized that central leptin infusion modifies muscle size through activation of insulin signaling. Muscle insulin signaling, enzymes of fatty acid metabolism, mitochondrial respiratory chain complexes, proliferating cell nuclear antigen (PCNA) and fiber area were analyzed in the gastrocnemius of chronic central infused (L), pair-fed (PF) and control rats. PCNA-positive nuclei, fiber area, GLUT4 and glycogen levels and activation of Akt and mechanistic target of rapamycin were increased in L, with no changes in PF. Acetyl-CoA carboxylase-ß mRNA levels and non-esterified fatty acid and triglyceride content were reduced and carnitine palmitoyltransferase-1b expression and mitochondrial complexes augmented in L. These results suggest that leptin promotes an increase in muscle size associated with improved insulin signaling favored by lipid profile.

Modulation of miRNA expression in aged rat hippocampus by buttermilk and krill oil.

The increasing incidence of age-induced cognitive decline justifies the search for complementary ways of prevention or delay. We studied the effects of concentrates of phospholipids, sphingolipids, and/or 3-n fatty acids on the expression of genes or miRNAs related to synaptic activity and/or neurodegeneration, in the hippocampus of aged Wistar rats following a 3-month supplementation. The combination of two phospholipidic concentrates of krill oil (KOC) and buttermilk (BMFC) origin modulated the hippocampal expression of 119 miRNAs (11 were common to both BMFC and BMFC + KOC groups). miR-191a-5p and miR-29a-3p changed significantly only in the BMFC group, whereas miR-195-3p and miR-148a-5p did so only in the combined-supplemented group. Thirty-eight, 58, and 72 differentially expressed genes (DEG) were found in the groups supplemented with KOC, BMFC and BMFC + KOC, respectively. Interaction analysis unveiled networks of selected miRNAs with their potential target genes. DEG found in the KOC and BMFC groups were mainly involved in neuroactive processes, whereas they were associated with lysosomes and mRNA surveillance pathways in the BMFC + KOC group. We also report a significant reduction in hippocampal ceramide levels with BMFC + KOC. Our results encourage additional in-depth investigations regarding the potential beneficial effects of these compounds.

Buttermilk and Krill Oil Phospholipids Improve Hippocampal Insulin Resistance and Synaptic Signaling in Aged Rats.

Impaired glucose metabolism and mitochondrial decay greatly increase with age, when cognitive decline becomes rampant. No pharmacological or dietary intervention has proven effective, but proper diet and lifestyle do postpone the onset of neurodegeneration and some nutrients are being investigated. We studied insulin signaling, mitochondrial activity and biogenesis, and synaptic signaling in the hippocampus and cortex following dietary supplementation with bioactive phospholipid concentrates of krill oil (KOC), buttermilk fat globule membranes (BMFC), and a combination of both in aged rats. After 3 months of supplementation, although all groups of animals showed clear signs of peripheral insulin resistance, the combination of KOC and BMFC was able to improve peripheral insulin sensitivity. We also explored brain energy balance. Interestingly, the hippocampus of supplemented rats-mainly when supplemented with BMFC or the combination of KOC and BMFC-showed an increase in intracellular adenosine triphosphate (ATP) levels, whereas no difference was observed in the cerebral cortex. Moreover, we found a significant increase of brain-derived neurotrophic factor (BDNF) in the hippocampus of BMFC+KO animals. In summary, dietary supplementation with KOC and/or BMFC improves peripheral and central insulin resistance, suggesting that their administration could delay the onset of these phenomena. Moreover, n-3 fatty acids (FAs) ingested as phospholipids increase BDNF levels favoring an improvement in energy state within neurons and facilitating both mitochondrial and protein synthesis, which are necessary for synaptic plasticity. Thus, dietary supplementation with n-3 FAs could protect local protein synthesis and energy balance within dendrites, favoring neuronal health and delaying cognitive decline associated to age-related disrepair.

Hydroxytyrosol restores proper insulin signaling in an astrocytic model of Alzheimer's disease.

Recent epidemiological evidence demonstrated that diabetes is a risk factor for AD onset and development. Indeed, meta-analyses of longitudinal epidemiologic studies show that diabetes increases AD risk by 50-100%, being insulin resistance (IR) the main binding link between diabetes and AD. Astrocytes are the foremost cerebral macroglial cells and are responsible for converting glucose into lactate and transfer it to neurons that use it as fuel, but Aß(1-42) impairs insulin signaling and glycogen storage. Recent prospective studies showed that the Mediterranean diet is associated with lower incidence of AD. We hypothesized that hydroxytyrosol (HT, the preeminent polyphenol of olives and olive oil) could exert beneficial effects on IR associated with AD and investigated it mechanisms of action in an astrocytic model of AD. The astrocytic cell line C6 was exposed to Aß(25-35) and co-incubated with HT for different periods. After treatment with Aß(25-35), astrocytes' viability was significantly decreased as compared with controls; however, both pre- and post-treatment with HT prevented this effect. Mechanistically, we found that the preventive role of HT on Aß(25-35)- induced cytotoxicity in astrocytes is moderated by an increased HT-induced activation of Akt, which is mediated by the insulin signaling pathway. In addition, we report that HT prevented the pronounced activation of mTOR, thereby restoring proper insulin signaling. In conclusion, we demonstrate that HT protects Aß(25-35)-treated astrocytes by improving insulin sensitivity and restoring proper insulin-signaling. These data provide some mechanistic insight on the observed inverse association between olive oil consumption and prevalence of cognitive impairment. © 2017 BioFactors, 43(4):540-548, 2017.