Fecal microbiota transplantation ameliorates high-fat diet-induced memory impairment in mice.

Gut dysbiosis is linked to metabolic and neurodegenerative diseases and comprises a plausible link between high-fat diet (HFD) and brain dysfunction. Here we show that gut microbiota modulation by either antibiotic treatment for 5 weeks or a brief 3-day fecal microbiota transplantation (FMT) regimen from low-fat (control) diet-fed mice decreased weight gain, adipose tissue hypertrophy, and glucose intolerance induced by HFD in C57BL/6 male mice. Notably, gut microbiota modulation by FMT completely reversed impaired recognition memory induced by HFD, whereas modulation by antibiotics had less pronounced effect. Improvement in recognition memory by FMT was accompanied by decreased HFD-induced astrogliosis in the hippocampal cornu ammonis region. Gut microbiome composition analysis indicated that HFD diminished microbiota diversity compared to control diet, whereas FMT partially restored the phyla diversity. Our findings reinforce the role of the gut microbiota on HFD-induced cognitive impairment and suggest that modulating the gut microbiota may be an effective strategy to prevent metabolic and cognitive dysfunction associated with unfavorable dietary patterns.

Behavioral, neuroplasticity and metabolic effects of 7,8-dihydroxy-4-methylcoumarin associated with physical activity in mice.

The search for strategies to develop resilience against metabolic and neuropsychiatric disorders has motivated the clinical and experimental assessment of early life interventions such as lifestyle-based and use of unconventional pharmacological compounds. In this study, we assessed the effects of voluntary physical activity and 7,8-Dihydroxy-4-methylcoumarin (DHMC), independently or in combination, over mice physiological and behavioral parameters, adult hippocampal and hypothalamic neurogenesis, and neurotrophic factors expression in the hypothalamus. C57Bl/6J mice were submitted to a 29-day treatment with DHMC and allowed free access to a running wheel. We found that DHMC treatment alone reduced fasting blood glucose levels. Moreover, physical activity showed an anxiolytic effect in the elevated plus maze task and DHMC produced additional anxiolytic behavior, evidenced by reduced activity during the light cycle in the physical activity group. Although we did not find any differences in hypothalamic or hippocampal adult neurogenesis, DHMC increased gene expression levels of VEGF, which was correlated to the reduced fasting glucose levels. In conclusion, our data emphasize the potential of physical activity in reducing development of neuropsychiatric conditions, such as anxiety, and highlights DHMC as an attractive compound to be investigated in future studies addressing neuropsychiatric disorders associated with metabolic conditions.

Glutamic acid promotes hair growth in mice.

Glutamic acid is the main excitatory neurotransmitter acting both in the brain and in peripheral tissues. Abnormal distribution of glutamic acid receptors occurs in skin hyperproliferative conditions such as psoriasis and skin regeneration; however, the biological function of glutamic acid in the skin remains unclear. Using ex vivo, in vivo and in silico approaches, we showed that exogenous glutamic acid promotes hair growth and keratinocyte proliferation. Topical application of glutamic acid decreased the expression of genes related to apoptosis in the skin, whereas glutamic acid increased cell viability and proliferation in human keratinocyte cultures. In addition, we identified the keratinocyte glutamic acid excitotoxic concentration, providing evidence for the existence of a novel skin signalling pathway mediated by a neurotransmitter that controls keratinocyte and hair follicle proliferation. Thus, glutamic acid emerges as a component of the peripheral nervous system that acts to control cell growth in the skin. These results raise the perspective of the pharmacological and nutritional use of glutamic acid to treat skin diseases.

Red wine consumption mitigates the cognitive impairments in low-density lipoprotein receptor knockout (LDLr-/-) mice.

Although the benefits of moderate intake of red wine in decreasing incidence of cardiovascular diseases associated to hypercholesterolemia are well recognized, there are still widespread misconceptions about its effects on the hypercholesterolemia-related cognitive impairments. Herein we investigated the putative benefits of regular red wine consumption on cognitive performance of low-density lipoprotein receptor knockout (LDLr-/-) mice, an animal model of familial hypercholesterolemia, which display cognitive impairments since early ages. The red wine was diluted into the drinking water to a final concentration of 6% ethanol and was available for 60 days for LDLr-/- mice fed a normal or high-cholesterol diet. The results indicated that moderate red wine consumption did not alter locomotor parameters and liver toxicity. Across multiple cognitive tasks evaluating spatial learning/reference memory and recognition/identification memory, hypercholesterolemic mice drinking red wine performed significantly better than water group, regardless of diet. Additionally, immunofluorescence assays indicated a reduction of astrocyte activation and lectin stain in the hippocampus of LDLr-/- mice under consumption of red wine. These findings demonstrate that the moderate consumption of red wine attenuates short- and long-term memory decline associated with hypercholesterolemia in mice and suggest that it could be through a neurovascular action.

Duloxetine Protects Human Neuroblastoma Cells from Oxidative Stress-Induced Cell Death Through Akt/Nrf-2/HO-1 Pathway.

The contribution of oxidative stress to the pathophysiology of depression has been described in numerous studies. Particularly, an increased production of reactive oxygen species (ROS) caused by mitochondrial dysfunction can lead to neuronal cell death. Human neuroblastoma SH-SY5Y cells were used to investigate the neuroprotective effect of the antidepressant duloxetine against rotenone-induced oxidative stress. SH-SY5Y cells were pretreated with duloxetine (1-5 µM) for 24 h followed by a 24-h rotenone exposure (10 µM). The phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) inhibitor LY294002 (10 µM) and the heme oxygenase 1 (HO-1) inhibitor zinc protoporphyrin IX-ZnPP (5 µM) were added to cultures 1 h prior duloxetine treatments. After treatments cell viability and ROS generation were assessed. NF-E2-related factor-2 (Nrf2) nuclear translocation was assessed by immunofluorescent staining after 4 and 8 h of duloxetine incubation. Furthermore, the Nrf2 and HO-1 mRNA expression was carried out after 4-48 h of duloxetine treatment by qRT-PCR. Duloxetine pretreatment antagonized rotenone-induced overproduction of ROS and cell death in SH-SY5Y cells. In addition, a 1-h pretreatment with LY294002 abolished duloxetine's protective effect. Duloxetine also induced nuclear translocation of the Nrf2 and the expression of its target gene, HO-1. Finally, the HO-1 inhibitor, ZnPP, suppressed the duloxetine protective effect. Overall, these results indicate that the mechanism of duloxetine neuroprotective action against oxidative stress and cell death might rely on the Akt/Nrf2/HO-1 pathways.

Is there an association between hypercholesterolemia and depression? Behavioral evidence from the LDLr(-/-) mouse experimental model.

Although epidemiological studies have reported an association between hypercholesterolemia and mood disorders, there is a lack of data regarding depressive-like behavior in animal models of hypercholesterolemia. To address these questions, we assessed depressive-like behavior and hippocampal and cortical monoaminergic metabolism in three-month-old, low-density lipoprotein receptor knockout (LDLr(-/-)) and C57BL/6 wild-type mice. The LDLr(-/-) mice exhibited depressive-like behavior in the sucrose preference test, splash test, and tail suspension test. Increased monoamine oxidase (MAO) A and B activity was evidenced in the hippocampus of LDLr(-/-) mice. Furthermore, to address whether or not cholesterol modulates MAO activity, we exposed SH-SY5Y human neuroblastoma cells to human isolated low-density lipoprotein (LDL). Notably, LDL increased the activity of MAO-A and stimulated the reactive species generation in vitro. These findings indicate that depressive-like behavior in hypercholesterolemic mice is accompanied by alterations in the monoaminergic metabolism, providing new evidence about the association between hypercholesterolemia and depression.

Succinobucol, a Lipid-Lowering Drug, Protects Against 3-Nitropropionic Acid-Induced Mitochondrial Dysfunction and Oxidative Stress in SH-SY5Y Cells via Upregulation of Glutathione Levels and Glutamate Cysteine Ligase Activity.

Succinobucol (succinyl ester of probucol) is a lipid-lowering compound with anti-inflammatory and antioxidant properties. Recent experimental evidence has highlighted the potential neuroprotective effects of succinobucol. In the present study, cultured neuroblastoma (SH-SY5Y) cells were used to investigate mechanisms mediating the potential protective effect of succinobucol against mitochondrial metabolic impairment and oxidative stress induced by 3-nitropropionic acid (3-NP), a succinate dehydrogenase inhibitor that has been used in experimental models of the Huntington disease (HD). 3-NP decreased cellular viability after 24 h of incubation. This decline in cellular viability was preceded by (i) reduced mitochondrial complex II activity, (ii) increased reactive species generation, (iii) decreased mitochondrial membrane potential (ΔΨm), and (iv) diminished glutathione (GSH) levels. Succinobucol pretreatment (6 days) significantly prevented 3-NP-induced loss of cellular viability, generation of reactive oxygen species, and decrease of ΔΨm. However, succinobucol pretreatment did not protect against 3-NP-induced inhibition of mitochondrial complex II activity, pointing to the mitigation of secondary events resultant from mitochondrial complex II inhibition. Succinobucol pretreatment (6 days) significantly increased (50 %) the levels of GSH in SH-SY5Y cells, and this event was paralleled by significant increases in glutamate cysteine ligase messenger RNA (mRNA) expression and activity (GCL; the first enzyme in the GSH biosynthesis). The present findings are the first to show that succinobucol increases GSH levels via upregulation of GCL activity (possibly through the activation of the nuclear (erythroid-derived 2)-related factor (Nrf2)/antioxidant response element (ARE) pathway), displaying protective effects against mitochondrial dysfunction-derived oxidative stress.

Hypercholesterolemia induces short-term spatial memory impairments in mice: up-regulation of acetylcholinesterase activity as an early and causal event?

Epidemiological studies have indicated hypercholesterolemia in midlife as a risk factor for dementia in later life, bringing cholesterol to the forefront of Alzheimer's disease research. Herein, we modeled mild hypercholesterolemia in mice to evaluate biochemical and behavioral alterations linked to hypercholesterolemia. Swiss mice were fed a high fat/cholesterol diet (20 % fat and 1.25 % cholesterol) for an 8-week period (from 12 to 18 weeks old) and were tested on the object location, forced swimming and elevated plus-maze tasks. We also investigated hypercholesterolemia-induced changes on acetylcholinesterase (AChE) activity, oxidative damage, amyloid precursor protein (APP) processing and blood brain barrier (BBB) integrity within the prefrontal cortex and hippocampus. It was found that increased AChE activity within the prefrontal cortex and hippocampus is an early event associated with hypercholesterolemia-induced short-term memory impairments. We observed no signs of antioxidant imbalance and/or oxidative damage or changes in cortical and hippocampal densities of beta-site amyloid precursor protein-cleaving enzyme 1 and aquaporin-4, biomarkers of APP processing and BBB integrity, respectively. In addition, we treated SH-SY5Y human neuroblastoma cells with low-density lipoprotein (LDL) cholesterol in an attempt to manipulate cell cholesterol content. Notably, LDL cholesterol increased in a dose-dependent manner the activity of AChE in SH-SY5Y cells. The present findings provide new evidence that increased AChE activity within the prefrontal cortex and hippocampus is an early event associated with hypercholesterolemia-induced cognitive impairments.