Diet-induced elevations in serum cholesterol are associated with alterations in hippocampal lipid metabolism and increased oxidative stress

Short-term high-fat diet alters behavior, peripheral metabolism, and brain mitochondrial function in Swiss mice

Understanding the temporal dynamics of high-fat diets (HFD) effects on behavior and metabolism is crucial for comprehending their negative impact on organisms. This study investigated the short-term effects (15, 25, and 35 days) of HFD in Swiss mice. Our findings revealed distinct behavioral and metabolic changes throughout the treatment. After 15 days of HFD, mice exhibited impaired exploratory habituation and significant increases in visceral adipose mass, fasting glucose levels, and glucose intolerance. Extending the diet to 25 days intensified the metabolic effects, resulting in compromised acquisition of recognition memory, increased body mass gain, and elevated plasma total cholesterol and triglyceride levels. After 35 days of HFD, these effects were further intensified and accompanied by anxiogenic-like responses in the open field test. Additionally, we observed a positive correlation between metabolic changes and behavioral impairments alongside prefrontal cortex mitochondrial dysfunction. In conclusion, our study reveals the temporal dynamics of behavioral and metabolic changes induced by short-term HFD in Swiss mice, highlighting the relationship between metabolic dysfunction and behavioral impairments. These findings pave the way for future research to unravel the underlying mechanisms and develop strategies to counteract the detrimental effects of HFD on behavior and metabolism.

Non-canonical pathways associated to Amyloid beta and tau protein dyshomeostasis in Alzheimer's disease: A narrative review

Alzheimer's Disease (AD) is the most common form of dementia among elderly people. This disease imposes a significant burden on the healthcare system, society, and economy due to the increasing global aging population. Current trials with drugs or bioactive compounds aimed at reducing cerebral Amyloid beta (Aβ) plaques and tau protein neurofibrillary tangles, which are the two main hallmarks of this devastating neurodegenerative disease, have not provided significant results in terms of their neuropathological outcomes nor met the expected clinical end-points. Ageing, genetic and environmental risk factors, along with different clinical symptoms suggest that AD is a complex and heterogeneous disorder with multiple interconnected pathological pathways rather than a single disease entity. In the present review, we highlight and discuss various non-canonical, Aβ-independent mechanisms, like gliosis, unhealthy dietary intake, lipid and sugar signaling, and cerebrovascular damage that contribute to the onset and development of AD. We emphasize that challenging the traditional "amyloid cascade hypothesis" may improve our understanding of this age-related complex syndrome and help fight the progressive cognitive decline in AD.

A mechanistic exploration of the metabolome of African mango seeds and its potential to alleviate cognitive impairment induced by high-fat/high-carbohydrate diets: Involvement of PI3K/AKT/GSK-3β/CREB, PERK/CHOP/Bcl-2, and AMPK/SIRT-1/mTOR Axes

ETHNOPHARMACOLOGICAL RELEVANCE

Irvingia gabonensis (Aubry-Lecomte ex O'Rorke) Baill., also known as "African mango" or "bush mango", belonging to family Irvingiaceae, has been mostly used as food and traditional medicine for weight loss and to enhance the health.

AIM OF THE STUDY

The overconsumption of high-fat and high-carbohydrate (HFHC) food induces oxidative stress, leading to neurological and cognitive dysfunction. Consequently, there is an immediate need for effective treatment. Hence, this study explored the efficacy of orlistat, metformin, and I. gabonensis seeds' total aqueous extract (IG SAE) in addressing HFHC-induced cognitive impairment by mitigating oxidative stress and their underlying mechanistic pathways.

MATERIALS AND METHODS

Initially, the secondary metabolite profile of IG SAE is determined using high-performance liquid chromatography coupled with a mass detector (UHPLC/MS). The in vivo study involves two phases: an established model phase with control (10 rats on a standard diet) and HFHC diet group (50 rats) for 3 months. In the study phase, HFHC is divided into 5 groups. The first subgroup receives HFHC diet only, while the remaining groups each receive HFHC diet with either Orlistat, metformin, or IG SAE at doses of 100 mg/kg and 200 mg/kg, respectively, for 28 days.

RESULTS

More than 150 phytoconstituents were characterized for the first holistic approach onto IG metabolome. Characterization of IG SAE revealed that tannins dominate metabolites in the plant. Total phenolics and flavonoids were estimated to standardize our extract (77.12 ± 7.09 μg Gallic acid equivalent/mg extract and 8.039 ± 0.53 μg Rutin equivalent/mg extract, respectively). Orlistat, metformin, and IG SAE successfully reduced the body weight, blood glucose level, lipid profile, oxidative stress and neurotransmitters levels leading to improved behavioral functions as well as histological alternation. Also, IG SAE halted inflammation, apoptosis, and endoplasmic reticulum stress, together with promoting autophagy, via modulation of PI3K/AKT/GSK-3β/CREB, PERK/CHOP/Bcl-2 and AMPK/SIRT-1/m-TOR pathways.

CONCLUSION

Metformin, orlistat, and IG SAE offer a promising multi-target therapy to mitigate HFHC diet-induced oxidative stress, addressing cognitive function. This involves diverse molecular mechanisms, particularly the modulation of inflammation, ER stress, and both PI3K/AKT/GSK-3β/CREB and AMPK/SIRT-1/m-TOR pathways. Furthermore, the higher dose of IG SAE demonstrated effects comparable to orlistat and metformin across most studied parameters.

The effects of orlistat on oxidative stress, recognition memory, spatial memory and hippocampal tissue in experimentally induced obesity in rats

This study investigates the impact of orlistat on oxidative stress, spatial memory, recognition memory, and hippocampal tissue in obese rats. The study groups were divided into control, high fat diet-induced obese (HFDIO), HFDIO+orlistat (HFDIO+ORL) groups, each consisting of 8 animals. While control fed with standart diet, HFDIO and HFDIO+ORL fed with high-fat diets for 8 weeks to induce obesity. Then, ORL treated 10 mg/kg for 7 weeks, while control and HFDIO get water. At 16th week, novel object recognition (NOR) and Morris water maze (MWM) tests were performed. TNF-alpha, IL-1beta levels in hippocampal tissue, and total/native thiol/disulphide levels in serum were measured. TNF-alpha level of HFDIO was higher than control, while lower in HFDIO+ORL compared to HFDIO as like IL-1beta level. On the contrary, serum total thiol level was lower in HFDIO than control and higher in HFDIO+ORL compared to the HFDIO, while disulphide level was opposite of the total thiol levels. While recognition index was higher in HFDIO+ORL, in MWM, latency of finding platform in HFDIO was higher than control and latency of HFDIO+ORL was very similar to control in 2-4 days. The HFDIO group demonstrated decrease in time spent in platform zone compared to control, whereas time spent of the HFDIO+ORL was higher than HFDIO. Our study demonstrates that orlistat administration exerts beneficial effects on oxidative stress, spatial memory, recognition memory, and hippocampal tissue in obese rats. It shows that orlistat may have potential therapeutic implications for obesity-related cognitive impairments and hippocampal dysfunction.

Short-term administration of tibolone reduces inflammation and oxidative stress in the hippocampus of ovariectomized rats fed high-fat and high-fructose

Inflammation and oxidative stress are critical events involved in neurodegeneration. In animal models, it has been shown that chronic consumption of a hypercaloric diet, which leads to inflammatory processes, affects the hippocampus, a brain region fundamental for learning and memory processes. In addition, advanced age and menopause are risk factors for neurodegeneration. Hormone replacement therapy (HRT) ameliorates menopause symptoms. Tibolone (TB), a synthetic hormone, exerts estrogenic, progestogenic and androgenic effects on different tissues. We aimed to determine the effect of short-term TB administration on oxidative stress and inflammation markers in the hippocampus of ovariectomized rats fed a high-fat-and-fructose diet (HFFD). Adult female rats were ovariectomized (OVX) and fed standard diet or HFFD-consisting of 10% lard supplemented chow and 20% high-fructose syrup in the drinking water-and administered vehicle or TB (1 mg/kg for seven days). Finally, we administered hormone receptor antagonists (MPP, RU486 or FLU) to each of the OVX + HFFD + TB groups. Bodyweight, triglycerides and cholesterol, oxidative stress and inflammation markers, and the activity and expression of antioxidant enzymes were quantified in the hippocampus of each experimental group. We observed that short-term TB administration significantly reduced body weight, AGEs, MDA levels, increased SOD and GPx activity, improved GSH/GSSG ratio, and reduced IL-6 and TNF-α. Our findings suggest that short-term administration of TB decreases oxidative stress and reduces inflammation caused by HFFD and early estrogenic decline. These effects occurred via estrogen receptor alpha.

Involvement of Lipids in the Pathogenesis of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive degeneration of upper and lower motor neurons. To study its underlying mechanisms, a variety of models are currently used at the cellular level and in animals with mutations in multiple ALS associated genes, including SOD1, C9ORF72, TDP-43, and FUS. Key mechanisms involved in the disease include excitotoxicity, oxidative stress, mitochondrial dysfunction, neuroinflammatory, and immune reactions. In addition, significant metabolism alterations of various lipids classes, including phospholipids, fatty acids, sphingolipids, and others have been increasingly recognized. Recently, the mechanisms of programmed cell death (apoptosis), which may be responsible for the degeneration of motor neurons observed in the disease, have been intensively studied. In this context, sphingolipids, which are the most important sources of secondary messengers transmitting signals for cell proliferation, differentiation, and apoptosis, are gaining increasing attention in the context of ALS pathogenesis given their role in the development of neuroinflammatory and immune responses. This review describes changes in lipids content and activity of enzymes involved in their metabolism in ALS, both summarizing current evidence from animal models and clinical studies and discussing the potential of new drugs among modulators of lipid metabolism enzymes.

Adult alcohol drinking and emotional tone are mediated by neutral sphingomyelinase during development in males

Alcohol use, abuse, and addiction, and resulting health hazards are highly sex-dependent with unknown mechanisms. Previously, strong links between the SMPD3 gene and its coded protein neutral sphingomyelinase 2 (NSM) and alcohol abuse, emotional behavior, and bone defects were discovered and multiple mechanisms were identified for females. Here we report strong sex-dimorphisms for central, but not for peripheral mechanisms of NSM action in mouse models. Reduced NSM activity resulted in enhanced alcohol consumption in males, but delayed conditioned rewarding effects. It enhanced the acute dopamine response to alcohol, but decreased monoaminergic systems adaptations to chronic alcohol. Reduced NSM activity increased depression- and anxiety-like behavior, but was not involved in alcohol use for the self-management of the emotional state. Constitutively reduced NSM activity impaired structural development in the brain and enhanced lipidomic sensitivity to chronic alcohol. While the central effects were mostly opposite to NSM function in females, similar roles in bone-mediated osteocalcin release and its effects on alcohol drinking and emotional behavior were observed. These findings support the view that the NSM and multiple downstream mechanism may be a source of the sex-differences in alcohol use and emotional behavior.

Peroxisomal Proliferator-Activated Receptor β/δ Deficiency Induces Cognitive Alterations

Peroxisome proliferator-activated receptor β/δ (PPARβ/δ), the most PPAR abundant isotype in the central nervous system, is involved in microglial homeostasis and metabolism, whose disturbances have been demonstrated to play a key role in memory impairment. Although PPARβ/δ function is well-established in metabolism, its contribution to neuronal and specifically memory process is underexplored. Therefore, the aim of the study is to determine the role of PPARβ/δ in the neuropathological pathways involved in memory impairment and as to whether a risk factor implicated in memory loss such as obesity modulates neuropathological markers. To carry out this study, 6-month-old total knock-out for the Ppard gene male mice with C57BL/6X129/SV background (PPARβ/δ-/-) and wild-type (WT) littermates with the same genetic background were used. Animals were fed, after the weaning (at 21 days old), and throughout their growth, either conventional chow (CT) or a palmitic acid-enriched diet (HFD). Thus, four groups were defined: WT CT, WT HFD, PPARβ/δ-/- CT, and PPARβ/δ-/- HFD. Before sacrifice, novel object recognition test (NORT) and glucose and insulin tolerance tests were performed. After that, animals were sacrificed by intracardiac perfusion or cervical dislocation. Different techniques, such as GolgiStain kit or immunofluorescence, were used to evaluate the role of PPARβ/δ in memory dysfunction. Our results showed a decrease in dendritic spine density and synaptic markers in PPARβ/δ-/- mice, which were corroborated in the NORT. Likewise, our study demonstrated that the lack of PPARβ/δ receptor enhances gliosis in the hippocampus, contributing to astrocyte and microglial activation and to the increase in neuroinflammatory biomarkers. Additionally, alterations in the hippocampal insulin receptor pathway were found. Interestingly, while some of the disturbances caused by the lack of PPARβ/δ were not affected by feeding the HFD, others were exacerbated or required the combination of both factors. Taken together, the loss of PPARβ/δ-/- affects neuronal and synaptic structure, contributing to memory dysfunction, and they also present this receptor as a possible new target for the treatment of memory impairment.

Global Proteome Profiling of the Temporal Cortex of Female Rats Exposed to Chronic Stress and the Western Diet

The increasing consumption of highly processed foods with high amounts of saturated fatty acids and simple carbohydrates is a major contributor to the burden of overweight and obesity. Additionally, an unhealthy diet in combination with chronic stress exposure is known to be associated with the increased prevalence of central nervous system diseases. In the present study, the global brain proteome approach was applied to explore protein alterations after exposure to the Western diet and/or stress. Female adult rats were fed with the Western diet with human snacks and/or subjected to chronic stress induced by social instability for 12 weeks. The consumption of the Western diet resulted in an obese phenotype and induced changes in the serum metabolic parameters. Consuming the Western diet resulted in changes in only 5.4% of the proteins, whereas 48% of all detected proteins were affected by chronic stress, of which 86.3% were down-regulated due to this exposure to chronic stress. However, feeding with a particular diet modified stress-induced changes in the brain proteome. The down-regulation of proteins involved in axonogenesis and mediating the synaptic clustering of AMPA glutamate receptors (Nptx1), as well as proteins related to metabolic processes (Atp5i, Mrps36, Ndufb4), were identified, while increased expression was detected for proteins involved in the development and differentiation of the CNS (Basp1, Cend1), response to stress, learning and memory (Prrt2), and modulation of synaptic transmission (Ncam1, Prrt2). In summary, global proteome analysis provides information about the impact of the combination of the Western diet and stress exposure on cerebrocortical protein alterations and yields insight into the underlying mechanisms and pathways involved in functional and morphological brain alterations as well as behavioral disturbances described in the literature.

Microglial FABP4-UCP2 Axis Modulates Neuroinflammation and Cognitive Decline in Obese Mice

The microglial fatty-acid-binding protein 4-uncoupling protein 2 (FABP4-UCP2) axis is a key regulator of neuroinflammation in high-fat-diet (HFD)-fed animals, indicating a role for FABP4 in brain immune response. We hypothesized that the FABP4-UCP2 axis is involved in regulating diet-induced cognitive decline. We tested cognitive function in mice lacking microglial FABP4 (AKO mice). Fifteen-week-old male AKO and wild-type (WT) mice were maintained on 60% HFD or normal chow (NC) for 12 weeks. Body composition was measured using EchoMRI. Locomotor activity, working memory, and spatial memory were assessed using behavioral tests (open field, T-maze, and Barnes maze, respectively). Hippocampal microgliosis was assessed via immunohistochemical staining. An inflammatory cytokine panel was assayed using hippocampal tissue. Real-time RT-PCR was performed to measure microglial UCP2 mRNA expression. Our data support that loss of FABP4 prevents cognitive decline in vivo. HFD-fed WT mice exhibited impaired long- and short-term memory, in contrast with HFD-fed AKO mice. HFD-fed WT mice had an increase in hippocampal inflammatory cytokine expression (IFNγ, IL-1β, IL-5, IL-6, KC/GRO(CXCL1), IL-10, and TNFα) and microgliosis, and decreased microglial UCP2 expression. HFD-fed AKO mice had decreased hippocampal inflammatory cytokine expression and microgliosis and increased microglial UCP2 expression compared to HFD-fed WT mice. Collectively, our work supports the idea that the FABP4-UCP2 axis represents a potential therapeutic target in preventing diet-induced cognitive decline.

B Vitamins Supplementation Can Improve Cognitive Functions and May Relate to the Enhancement of Transketolase Activity in A Rat Model of Cognitive Impairment Associated with High-fat Diets

OBJECTIVE

To determine whether B vitamin treatment was sufficient to reduce cognitive impairment associated with high-fat diets in rats and to modulate transketolase (TK) expression and activity.

METHODS

To test this, we separated 50 rats into five groups that were either fed a standard chow diet (controls) or a high-fat diet (experimental groups H0, H1, H2, and H3). H0 group animals received no additional dietary supplementation, while H1 group animals were administered 100 mg/kg body weight (BW) thiamine, 100 mg/kg BW riboflavin, and 250 mg/kg BW niacin each day, and group H2 animals received daily doses of 100 mg/kg BW pyridoxine, 100 mg/kg BW cobalamin, and 5 mg/kg BW folate. Animals in the H3 group received the B vitamin regimens administered to both H1 and H2 each day.

RESULTS

Over time, group H0 exhibited greater increases in BW and fat mass relative to other groups. When spatial and memory capabilities in these animals were evaluated via conditioned taste aversion (CTA) and Morris Water Maze (MWM), we found B vitamin treatment was associated with significant improvements relative to untreated H0 controls. Similarly, B vitamin supplementation was associated with elevated TK expression in erythrocytes and hypothalamus of treated animals relative to those in H0 (P<0.05).

CONCLUSION

Together, these findings suggest B vitamin can modulate hypothalamic TK activity to reduce the severity of cognitive deficits in a rat model of obesity. As such, B vitamin supplementation may be a beneficial method for reducing cognitive dysfunction in clinical settings associated with high-fat diets.

[The role of sphingolipids in pathogenesis of amyotrophic lateral sclerosis]

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease characterized by selective degeneration of motor neurons of the spinal cord and motor cortex and brain stem. The key features of the course of this disease are excitotoxicity, oxidative stress, mitochondrial dysfunction, neuro-inflammatory and immune reactions. Recently, the mechanisms of programmed cell death (apoptosis), which may be responsible for the degeneration of motor neurons in this disease, have been intensively studied. In this regard, sphingolipids, which are the most important sources of secondary messengers that transmit cell proliferation, differentiation and apoptosis signals, and are involved in the development of neuroinflammatory and immune responses, are of particular interest in the context of ALS pathogenesis. The review provides information from domestic and foreign authors on the involvement of various sphingolipids (sphingomyelins, ceramides, sphingosine, sphinganin, sphingosine-1-phosphate, galactosylceramides, glucosylceramides, gangliosides) in the development of pro-inflammatory reactions and apoptosis of motor neurons in ALS. The authors discuss the prospects of using new drugs that control the metabolism of sphingolipids for the treatment of ALS.

High fat diet and its effects on cognitive health: alterations of neuronal and vascular components of brain

It has been well recognized that intake of diets rich in saturated fats could result in development of metabolic disorders such as type 2 diabetes mellitus, obesity and cardiovascular diseases. Recent studies have suggested that intake of high fat diet (HFD) is also associated with cognitive dysfunction. Various preclinical studies have demonstrated the impact of short and long term HFD feeding on the biochemical and behavioural alterations. This review summarizes studies and the protocols used to assess the impacts of HFD feeding on cognitive performance in rodents. Further, it discuss the key mechanisms that are altered by HFD feeding, such as, insulin resistance, oxidative stress, neuro-inflammation, transcriptional dysregulation and loss of synaptic plasticity. Along with these, HFD feeding also alters the vascular components of brain such as loss of BBB integrity and reduced cerebral blood flow. It is highly possible that these factors are responsible for the development of cognitive deficits as a result of HFD feeding.

Effect of Allopregnanolone on Spatial Memory and Synaptic Proteins in Animal Model of Metabolic Syndrome

Metabolic Syndrome (MetS) is considered a common disorder, especially with a sedentary lifestyle and unhealthy food consumption. Cognitive impairment is one of the MetS consequences that worsens the quality of life of the patients. The study aimed to assess the therapeutic effect of the neurosteroid Allopregnalonone on spatial memory and, therefore, the expression of two synaptic plasticity markers in the hippocampus. Thirty-two male rats were divided into four groups: control groups, MetS, and MetS + Allopregnalone. Spatial memory has been evaluated by the Y-maze task and blood pressure measured by the rat tail method. Biochemical evaluation of serum glucose, insulin, lipid profile, and hippocampal expression of Synaptophysin and Associated Protein 43 (GAP-43) were performed for assessing Allopregnanolone on serum and hippocampal markers. Allopregnanolone therapy improved working spatial memory, hypertension, and biochemical markers measured in the serum and hippocampus.

Cerebrospinal Fluid C18 Ceramide Associates with Markers of Alzheimer's Disease and Inflammation at the Pre- and Early Stages of Dementia

Background:

Understanding how dysregulation in lipid metabolism relates to the severity of Alzheimer‘s disease (AD) pathology might be critical in developing effective treatments.

Objective:

To identify lipid species in cerebrospinal fluid (CSF) associated with signature AD pathology and to explore their relationships with measures reflecting AD-related processes (neurodegeneration, inflammation, deficits in verbal episodic memory) among subjects at the pre- and early symptomatic stages of dementia.

Methods:

A total of 60 subjects that had been referred to an Icelandic memory clinic cohort were classified as having CSF AD (n = 34) or non-AD (n = 26) pathology profiles. Untargeted CSF lipidomic analysis was performed using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) for the detection of mass-to-charge ratio (m/z) features. CSF proteins reflecting neurodegeneration (neurofilament light [NFL]) and inflammation (chitinase-3-like protein 1 [YKL-40], S100 calcium-binding protein B [S100B], glial fibrillary acidic protein [GFAP]) were also measured. Rey Auditory Verbal Learning (RAVLT) and Story tests were used for the assessment of verbal episodic memory.

Results:

Eight out of 1008 features were identified as best distinguishing between the CSF profile groups. Of those, only the annotation of the m/z feature assigned to lipid species C18 ceramide was confirmed with a high confidence. Multiple regression analyses, adjusted for age, gender, and education, demonstrated significant associations of CSF core AD markers (Aβ₄₂: st.β= –0.36, p = 0.007; T-tau: st.β= 0.41, p = 0.005) and inflammatory marker S100B (st.β= 0.51, p = 0.001) with C18 ceramide levels.

Conclusion:

Higher levels of C18 ceramide associated with increased AD pathology and inflammation, suggesting its potential value as a therapeutic target.

Metabolic regulation of aging and age-related disease

Inquiry into relationships between energy metabolism and brain function requires a uniquely interdisciplinary mindset, and implementation of anti-aging lifestyle strategies based on this work also involves consistent mental and physical discipline. Dr. Mark P. Mattson embodies both of these qualities, based on the breadth and depth of his work on neurobiological responses to energetic stress, and on his own diligent practice of regular exercise and caloric restriction. Dr. Mattson created a neurotrophic niche in his own laboratory, allowing trainees to grow their skills, form new connections, and eventually migrate, forming their own labs while remaining part of the extended lab family. In this historical review, we highlight Dr. Mattson's many contributions to understanding neurobiological responses to physical exercise and dietary restriction, with an emphasis on the mechanisms that may underlie neuroprotection in ageing and age-related disease. On the occasion of Dr. Mattson's retirement from the National Institute on Aging, we highlight his foundational work on metabolism and neuroplasticity by reviewing the context for these findings and considering their impact on future research on the neuroscience of aging.

Nuclear Factor [Erythroid-derived 2]-like 2 and Mitochondrial Transcription Factor A Contribute to Moderate-intensity Swimming Effectiveness against Memory Impairment in Young Mice Induced by Concomitant Exposure to a High-calorie Diet during the Early Life Period

Increased energy food consumption during early-life has been associated with memory impairment. Swimming training has been reported to improve memory processes in rodent models. This study aimed to evaluate whether moderate-intensity swimming training counteracts learning and memory impairment in young mice fed a high-calorie diet during the early-life period. The contribution of hippocampal oxidative stress, as well as nuclear factor [erythroid-derived 2]-like 2/Kelch-like ECH-associated protein (NRF2/Keap-1/HO-1) and peroxisome proliferator-activated receptor gamma co-activator 1-alpha/mitochondrial transcription factor A (PCG-1α/mtTFA) signaling, in memory effects was also investigated. Three-week-old male Swiss mice received a high-calorie diet (20% fat; 20% carbohydrate enriched) or a standard diet from 21 to 49 postnatal days. Mice performed a moderate-intensity swimming protocol (5 days/week) and behavioral tests predictive of memory function. Mice fed a high-calorie diet and subjected to the swimming protocol performed better on short- and long-term spatial and object recognition memory tests than those fed a high-calorie diet. The swimming protocol modulated the hippocampal NRF2/Keap-1/HO-1 and mtTFA pathways in mice fed a high-calorie diet. Swimming training positively affected location and long-term memory, fat mass content, as well as NRF2/Keap-1/HO-1 and mtTFA proteins of control-diet-fed mice. In conclusion, a moderate-intensity swimming training evoked an adaptive response in mice fed a high-calorie diet by restoring different types of memory-impaired and hippocampal oxidative stress as well as upregulated the NRF2/Keap-1/HO-1 and mtTFA pathways.

Dill tablet and Ocimum basilicum aqueous extract: Promising therapeutic agents for improving cognitive deficit in hypercholesterolemic rats

High-cholesterol diet (HCD) is correlated with Alzheimer's disease (AD) and impairment of memory. This study investigated beneficial therapeutic effects of Dill tablet and Ocimum basilicum (Basil) aqueous extract on hypercholesterolemia-induced cognitive deficits and oxidative stress in hippocampus tissues of rats. Hippocampal Aβ(1-42) level was measured. The gene expression levels of superoxide dismutase and inducible-nitric oxide synthase were determined in hippocampus. Cognitive functions were examined and oxidative status was evaluated in serum and hippocampus. Phytochemical properties and in vitro antioxidant activity of Basil extract were assessed. HCD significantly increased serum cholesterol, induced deposition of Aβ plaque, altered hippocampus morphology, and impaired memory function, whereas receiving Basil extract or Dill tablet increased antioxidant potency in serum and hippocampus and normalized HCD-induced deleterious effects. Basil extract and Dill tablet may exhibit their beneficial effects in AD by lowering serum cholesterol and evoking antioxidant system in the brain. PRACTICAL APPLICATIONS: Dill tablet and Basil aqueous extract lowered serum cholesterol in hypercholesterolemic animal models, therefore, they can be used as hypocholesterolemic agents. These edible herbs significantly retarded deposition of Aβ plaque and normalized hippocampal morphology, thus, they favorably protected hippocampus tissue from deleterious effects-induced by hypercholesterolemia. Dill tablet and Basil aqueous extract also corrected oxide-redox balance and normalized HCD-induced oxidative stress to some extent and significantly improved impairments in learning and memory suggesting that these medicinal plants can be considered as surrogate therapeutic agents for the synthetic medicines in the treatment of AD and in postponement of its complications.

High-Fat Diet Causes Constipation in Mice via Decreasing Colonic Mucus

BACKGROUND

Constipation is one of the most common gastrointestinal complaints. Although the causes of constipation are varied, dietary habits have a significant influence. Excessive fat intake is suggested as one of the main causes of constipation; however, the exact mechanism is unknown.

AIMS

To investigate whether a high-fat diet (HFD) causes constipation in mice and to clarify the underlying mechanism, focusing on the amount of colonic mucus.

METHODS

Six-week-old male C57BL/6 mice were randomly divided into two groups: mice fed with HFD and those with normal chow diet (NCD). Fecal weight, water content, total gastrointestinal transit time, and colon transit time were measured to determine whether the mice were constipated. The colonic mucus was evaluated by immunostaining and quantified by spectrometry. Malondialdehyde (MDA) was measured using the thiobarbituric acid (TBA) test as a marker for oxidative stress.

RESULTS

Compared to the NCD group, the weight of feces was less in the HFD group. In the functional experiment, the total gastrointestinal transit time and colon transit time were longer in the HFD group. Furthermore, HFD significantly reduced the amount of colonic mucus. In addition, the reduction in colonic mucus caused by surfactant resulted in constipation in the NCD group.

CONCLUSIONS

HFD causes constipation with delayed colon transit time possibly via the reduction in colonic mucus in mice.

Severity of psychosis syndrome and change of metabolic abnormality in chronic schizophrenia patients: Severe negative syndrome may be related to a distinct lipid pathophysiology

Background:

Metabolic abnormality is common among schizophrenia patients. Some metabolic traits were found associated with subgroups of schizophrenia patients.

Objectives:

We examined a possible relationship between metabolic abnormality and psychosis profile in schizophrenia patients.

Method:

Three hundred and seventy-two chronic schizophrenia patients treated with antipsychotics for more than 2 years were assessed with the Positive and Negative Syndrome Scale. A set of metabolic traits was measured at scheduled checkpoints between October 2004 and September 2006.

Results:

Multiple regressions adjusted for sex showed negative correlations between body mass index (BMI) and total score and all subscales; triglycerides (TG) was negatively correlated with total score and negative syndrome, while HDLC was positively correlated with negative syndrome. When sex interaction was concerned, total score was negatively correlated with BMI but not with others; negative syndrome was negatively correlated with BMI and positively with HDLC. No metabolic traits were correlated with positive syndrome or general psychopathology.

Conclusions:

Loss of body weight is a serious health problem in schizophrenia patients with severe psychosis syndrome, especially the negative syndrome. Schizophrenia patients with severe negative syndrome may have a distinct lipid pathophysiology in comparison with those who were less severe in the domain.

Effects of metformin on recognition memory and hippocampal neuroplasticity in rats with metabolic syndrome

Metabolic syndrome (MS) is a health problem that is characterized by body fat accumulation, hypertension, dyslipidemia, and hyperglycemia; recently, it has been demonstrated that MS also damages memory processes. The first-line drug in the treatment of MS and type 2 diabetes mellitus is metformin, which is an antihyperglycemic agent. This drug has been shown to produce neuroprotection and to improve memory processes. However, the mechanism involved in this neuroprotection is unknown. A 90-day administration of metformin improved the cognitive processes of rats with MS as evaluated by the novel object recognition test, and this finding could be explained by an increase in the neuronal spine density and spine length. We also found that metformin increased the immunoreactivity of synaptophysin, sirtuin-1, AMP-activated protein kinase, and brain-derived neuronal factor, which are important plasticity markers. We conclude that metformin is an important therapeutic agent that increases neural plasticity and protects cognitive processes. The use of this drug is important in the minimization of the damage caused by MS.

Cerebrospinal fluid lipidomics: effects of an intravenous triglyceride infusion and apoE status

INTRODUCTION

High-fat diets increase risk for Alzheimer's disease, but individuals with the risk gene APOE ε4 (E4) paradoxically have improved memory soon after high fat feeding. Little is known about how dietary lipids affect CNS lipids, especially in older adults.

OBJECTIVES

We analyzed the lipidomic signature of cerebrospinal fluid (CSF) in older adults who underwent both a saline and TG infusion. We further analyzed these data by E4 carrier status.

METHODS

Older adults (n = 21, age 67.7 ± 8.6) underwent a 5-h TG and saline infusion on different days in random crossover design; lumbar CSF was collected at the end of the infusion. Lipids were extracted using dichloromethane/methanol and 13 classes of lipids analyzed using the Lipidyzer platform consisting of an AB Sciex 5500 MS/MS QTraps system equipped with a SelexION for differential mobility spectrometry (DMS). Multiple reaction monitoring was used to target and quantify 1070 lipids in positive and negative ionization modes with and without DMS.

RESULTS

The TG infusion increased total lipids in the CSF, including the appearance of more lipids at the detection limit in the TG samples compared to saline (Chi square p < 0.0001). The infusion increased the total level of diacylglycerols and lysophosphatidylcholines and reduced dihydroceramides. Of the possible 1070 lipids detectable, we found 348 after saline and 365 after TG infusion. Analysis using MetaboAnalyst revealed 11 specific lipids that changed; five of these lipids decreased after TG infusion, and four of them differed by E4 status, but none differed by cognitive diagnosis or sex.

CONCLUSION

These results in older adults show that blood lipids affect lipid profiles in CSF and such profiles are modified by APOE status. This suggests that how the CNS handles lipids may be important in the AD phenotype.

Complex interaction of dietary fat and Alaskan bog blueberry supplementation influences manganese mediated neurotoxicity and behavioral impairments

Dietary fat modulates neuronal health and contributes to age-related nervous system disorders. However, the complex interaction between dietary fat and supplementation and its consequences on neurotoxic pathophysiology has been sparsely explored. The indigenous Alaskan bog blueberry (BB), Vaccinum uliginosum, is known to have anti-inflammatory properties, mostly attributed to its rich polyphenolic content. Here, we evaluate the interplay between dietary fat and BB supplementation on sub-chronic manganese (Mn) exposure that inflicts neurotoxicity and behavioral impairments. In both low-fat and normal-fat diets, BB supplementation attenuated the behavioral and the molecular hallmarks of Mn-induced neurotoxicity. On the contrary, a high-fat diet was found to exacerbate these Mn-induced pathological features. Furthermore, BB supplementation failed to recover the behavioral deficits in mice subjected to a high fat diet in Mn-treated mice. Overall, our results demonstrate the importance of including a dietary regimen comprised of polyphenolic rich supplements with low-fat content in combating age-related neurodegenerative disorders.

Disruption of the hippocampal and hypothalamic blood-brain barrier in a diet-induced obese model of type II diabetes: prevention and treatment by the mitochondrial carbonic anhydrase inhibitor, topiramate

BACKGROUND

Type II diabetes is a vascular risk factor for cognitive impairment and increased risk of dementia. Disruption of the blood-retinal barrier (BRB) and blood-brain barrier (BBB) are hallmarks of subsequent retinal edema and central nervous system dysfunction. However, the mechanisms by which diet or metabolic syndrome induces dysfunction are not understood. A proposed mechanism is an increase in reactive oxygen species (ROS) and oxidative stress. Inhibition of mitochondrial carbonic anhydrase (mCA) decreases ROS and oxidative stress. In this study, topiramate, a mCA inhibitor, was examined for its ability to protect the BRB and BBB in diet-induced obese type II diabetic mice.

METHODS

BBB and BRB permeability were assessed using 14C-sucrose and 99mTc-albumin in CD-1 mice fed a low-fat (control) or a high-fat diet. Topiramate administration was compared to saline controls in both preventative and efficacy arms examining BRB and BBB disruption. Body weight and blood glucose were measured weekly and body composition was assessed using EchoMRI. Metabolic activity was measured using a comprehensive laboratory animal monitoring system. Brain tissues collected from the mice were assessed for changes in oxidative stress and tight junction proteins.

RESULTS

High-fat feeding caused increased entry of 14C-sucrose and 99mTc-albumin into the brains of diet-induced obese type II diabetic mice. Increased permeability to 14C-sucrose was observed in the hypothalamus and hippocampus, and attenuated by topiramate treatment, while increased permeability to 99mTc-albumin occurred in the whole brain and was also attenuated by topiramate. Treatment with topiramate decreased measures of oxidative stress and increased expression of the tight junction proteins ZO-1 and claudin-12. In the retina, we observed increased entry of 99mTc-albumin simultaneously with increased entry into the whole brain during the preventative arm. This occurred prior to increased entry to the retina for 14C-sucrose which occurred during the efficacy arm. Treatment with topiramate had no effect on the retina.

CONCLUSIONS

Blood-brain barrier and blood-retinal barrier dysfunction were examined in a mouse model of diet-induced obese type II diabetes. These studies demonstrate that there are spatial and temporal differences in 14C-sucrose and 99mTc-albumin permeability in the brain and retina of diet-induced obese type II diabetic mice. Topiramate, a mitochondrial carbonic anhydrase inhibitor, is efficacious at both preventing and treating BBB disruption in this diet-induced obese type II diabetic mouse model.

High fat diet increases cognitive decline and neuroinflammation in a model of orexin loss

Midlife obesity is a risk factor for cognitive decline and is associated with the earlier onset of Alzheimer's disease (AD). Diets high in saturated fat potentiate the onset of obesity, microglial activation, and neuroinflammation. Signaling deficiencies in the hypothalamic peptide orexin and/or orexin fiber loss are linked to neurodegeneration, cognitive impairment, and neuroinflammation. Prior studies show that orexin is neuroprotective, suppresses neuroinflammation, and that treatment with orexin improves cognitive processes in orexin/ataxin-3 (O/A3) mice, a transgenic mouse model of orexin neurodegeneration. Our overall hypothesis is that loss of orexin contributes to high fat diet (HFD)-induced hippocampal neuroinflammation and cognitive decline. To examine this, we tested male O/A3 mice (7-8 mo. of age) in a two-way active avoidance (TWAA) hippocampus-dependent memory task. We tested whether (1) orexin loss impaired cognitive function; (2) HFD worsened cognitive impairment; and (3) HFD increased microglial activation and neuroinflammation. O/A3 mice showed significant impairments in TWAA task learning vs. wild type (WT) mice (increased escapes p < 0.05, reduced avoidances p < 0.0001). Mice were then placed on HFD (45% total fat, 31.4% saturated fat) or remained on normal chow (NC; 4% total fat and 1% saturated fat), and TWAA was retested at 2 and 4 weeks. Learning impairment was evident at both 2 and 4 weeks in O/A3 mice fed HFD for following diet exposure vs. WT mice on normal chow or HFD (increased escapes, reduced avoidances p < 0.05). Additionally, O/A3 mice had increased gene expression of the microglial activation marker Iba-1 (measured via qRT-PCR, p < 0.001). Further characterization of the microglial immune response genes in hippocampal tissue revealed a significant increase in CX3 chemokine receptor 1 (CX3CR1), tumor necrosis factor-alpha (TNF-α) and the mitochondria-associated enzyme immune responsive gene-1 (Irg1). Collectively, our results indicate that orexin loss impairs memory, and that HFD accelerates hippocampus-dependent learning deficits and the onset of neuroinflammation.

Effects of the hydroalcoholic extract of Rosa damascena on learning and memory in male rats consuming a high-fat diet

CONTEXT

High-fat diet (HFD) can cause deficits in learning and memory through oxidative stress and increase Alzheimer disease risk. Rosa damascena Mill. (Rosaceae) extract possesses potent antioxidant properties.

OBJECTIVE

This study investigated the effects of the hydroalcoholic extracts of petals of R. damascena on learning and memory in male rats consuming an HFD.

MATERIALS AND METHODS

Forty male Wistar rats (200-250 g) were randomly assigned to four groups: control, R. damascena extract, HFD and HFD + extract. The extract (1 g/kg bw daily) was administered by oral gavage for 1 month. Animals were allowed free access to high-fat chow for 3 months. The Morris water maze and the passive avoidance learning tests were used to assess learning and memory.

RESULTS

In the passive avoidance learning test, the step-through latencies in the retention test (STLr) of the extract (147.4 ± 23.3) and HFD (150.3 ± 25.2) groups were significantly lower than those of the control group (270.4 ± 10.5) (respectively, p < 0.001 and p < 0.01). STLr was significantly higher in the HFD + extract group (265.3 ± 10.6) than in the HFD group (150.3 ± 25.2) (p < 0.01). Time spent in the dark compartment (TDC) in the HFD + extract group (5.3 ± 2.6) was significantly lower than that in the HFD group (85.8 ± 19.1) (p < 0.05).

DISCUSSION AND CONCLUSION

Our results indicate that, while HFD or R. damascena extract alone leads to memory deficits, R. damascena extract exerted a positive effect on HFD-induced memory deficits. We hypothesize that the observed effects of R. damascena extract are likely due to its strong antioxidant properties.

Mitochondrial dysfunction in obesity

Obesity leads to various changes in the body. Among them, the existing inflammatory process may lead to an increase in the production of reactive oxygen species (ROS) and cause oxidative stress. Oxidative stress, in turn, can trigger mitochondrial changes, which is called mitochondrial dysfunction. Moreover, excess nutrients supply (as it commonly is the case with obesity) can overwhelm the Krebs cycle and the mitochondrial respiratory chain, causing a mitochondrial dysfunction, and lead to a higher ROS formation. This increase in ROS production by the respiratory chain may also cause oxidative stress, which may exacerbate the inflammatory process in obesity. All these intracellular changes can lead to cellular apoptosis. These processes have been described in obesity as occurring mainly in peripheral tissues. However, some studies have already shown that obesity is also associated with changes in the central nervous system (CNS), with alterations in the blood-brain barrier (BBB) and in cerebral structures such as hypothalamus and hippocampus. In this sense, this review presents a general view about mitochondrial dysfunction in obesity, including related alterations, such as inflammation, oxidative stress, and apoptosis, and focusing on the whole organism, covering alterations in peripheral tissues, BBB, and CNS.

Estradiol Uses Different Mechanisms in Astrocytes from the Hippocampus of Male and Female Rats to Protect against Damage Induced by Palmitic Acid

An excess of saturated fatty acids can be toxic for tissues, including the brain, and this has been associated with the progression of neurodegenerative diseases. Since palmitic acid (PA) is a free fatty acid that is abundant in the diet and circulation and can be harmful, we have investigated the effects of this fatty acid on lipotoxicity in hippocampal astrocytes and the mechanism involved. Moreover, as males and females have different susceptibilities to some neurodegenerative diseases, we accessed the responses of astrocytes from both sexes, as well as the possible involvement of estrogens in the protection against fatty acid toxicity. PA increased endoplasmic reticulum stress leading to cell death in astrocytes from both males and females. Estradiol (E2) increased the levels of protective factors, such as Hsp70 and the anti-inflammatory cytokine interleukin-10, in astrocytes from both sexes. In male astrocytes, E2 decreased pJNK, TNFα, and caspase-3 activation. In contrast, in female astrocytes E2 did not affect the activation of JNK or TNFα levels, but decreased apoptotic cell death. Hence, although E2 exerted protective effects against the detrimental effects of PA, the mechanisms involved appear to be different between male and female astrocytes. This sexually dimorphic difference in the protective mechanisms induced by E2 could be involved in the different susceptibilities of males and females to some neurodegenerative processes.

Effects of Hypericum scabrum extract on learning and memory and oxidant/antioxidant status in rats fed a long-term high-fat diet

A high-fat diet (HFD) causes deficits in learning and memory by increasing oxidative stress. Antioxidants are known to improve learning and memory. Since Hypericum scabrum (H. scabrum) extract is rich in antioxidants, the aim of this study was to investigate the effects of the administration of H. scabrum extract on passive avoidance learning (PAL), novel object recognition (NOR), and locomotor activity in male rats on a HFD. Fifty-four male Wistar rats (weighing 220 ± 10 g) were divided into the following six groups: (1) Control (standard diet), (2) Ext100 (standard diet supplemented with 100 mg/kg extract once/day), (3) Ext300 (standard diet supplemented with 300 mg/kg extract once/day), (4) HFD (high-fat diet), (5) HFD + Ext100, and (6) HFD + Ext300. Rats in these groups were maintained on their respective diets for 3 months. In the PAL test, the step-through latencies in the retention test (STLr) were significantly higher in the HFD + extract group than in the HFD group. The time spent in the dark compartment (TDC) was significantly lesser and the time spent in exploring the novel object was significantly greater in the HFD + extract group than in the HFD group. In the HFD-fed rats, the activity of catalase had significantly decreased, and level of malondialdehyde had significantly increased; H. scabrum extract administration significantly reversed these changes. In conclusion, these results suggested that the administration of H. scabrum extract and its strong antioxidant properties enhanced learning and memory and reversed the memory impairment induced by chronic HFD consumption.

Whole-Body Vibration Mimics the Metabolic Effects of Exercise in Male Leptin Receptor-Deficient Mice

Whole-body vibration (WBV) has gained attention as a potential exercise mimetic, but direct comparisons with the metabolic effects of exercise are scarce. To determine whether WBV recapitulates the metabolic and osteogenic effects of physical activity, we exposed male wild-type (WT) and leptin receptor-deficient (db/db) mice to daily treadmill exercise (TE) or WBV for 3 months. Body weights were analyzed and compared with WT and db/db mice that remained sedentary. Glucose and insulin tolerance testing revealed comparable attenuation of hyperglycemia and insulin resistance in db/db mice following TE or WBV. Both interventions reduced body weight in db/db mice and normalized muscle fiber diameter. TE or WBV also attenuated adipocyte hypertrophy in visceral adipose tissue and reduced hepatic lipid content in db/db mice. Although the effects of leptin receptor deficiency on cortical bone structure were not eliminated by either intervention, exercise and WBV increased circulating levels of osteocalcin in db/db mice. In the context of increased serum osteocalcin, the modest effects of TE and WBV on bone geometry, mineralization, and biomechanics may reflect subtle increases in osteoblast activity in multiple areas of the skeleton. Taken together, these observations indicate that WBV recapitulates the effects of exercise on metabolism in type 2 diabetes.

Chronic psychological stress and high-fat high-fructose diet disrupt metabolic and inflammatory gene networks in the brain, liver, and gut and promote behavioral deficits in mice

The mechanisms underlying the association between chronic psychological stress, development of metabolic syndrome (MetS), and behavioral impairment in obesity are poorly understood. The aim of the present study was to assess the effects of mild chronic psychological stress on metabolic, inflammatory, and behavioral profiles in a mouse model of diet-induced obesity. We hypothesized that (1) high-fat high-fructose diet (HFHF) and psychological stress would synergize to mediate the impact of inflammation on the central nervous system in the presence of behavioral dysfunction, and that (2) HFHF and stress interactions would impact insulin and lipid metabolism. C57Bl/6 male mice underwent a combination of HFHF and two weeks of chronic psychological stress. MetS-related conditions were assessed using untargeted plasma metabolomics, and structural and immune changes in the gut and liver were evaluated. Inflammation was measured in plasma, liver, gut, and brain. Our results show a complex interplay of diet and stress on gut alterations, energetic homeostasis, lipid metabolism, and plasma insulin levels. Psychological stress and HFHF diet promoted changes in intestinal tight junctions proteins and increases in insulin resistance and plasma cholesterol, and impacted the RNA expression of inflammatory factors in the hippocampus. Stress promoted an adaptive anti-inflammatory profile in the hippocampus that was abolished by diet treatment. HFHF increased hippocampal and hepatic Lcn2 mRNA expression as well as LCN2 plasma levels. Behavioral changes were associated with HFHF and stress. Collectively, these results suggest that diet and stress as pervasive factors exacerbate MetS-related conditions through an inflammatory mechanism that ultimately can impact behavior. This rodent model may prove useful for identification of possible biomarkers and therapeutic targets to treat metabolic syndrome and mood disorders.

Hyperlipidemia-induced apoptosis of hippocampal neurons in apoE(-/-) mice may be associated with increased PCSK9 expression

Hyperlipidemia is a risk factor for Alzheimer's disease (AD) and other neurodegenerative diseases. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a lipid regulatory gene involved in cell apoptosis. However, the function and mechanism of PCSK9 in neuronal apoptosis following hyperlipidemia remains to be elucidated. The present study established a hyperlipidemic mouse model by feeding a high-fat diet (HFD) to 6-week-old apoE(−/−) mice. Plasma lipid levels, hippocampal lipid accumulation, hippocampal histology, and hippocampal neuronal apoptosis were all monitored for changes. The expression levels of PCSK9, β-secretase 1 (BACE1), B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), and caspase-3 in hippocampal CA3 and CA1 neurons were also measured. Results demonstrated that a HFD increased the lipid accumulation in the CA3 hippocampus and the levels of plasma lipids, including triglycerides, total cholesterol, low-density lipoprotein, and high-density lipoprotein. In addition, CA3 neurons in the HFD group indicated apparent injuries and increased neuronal apoptosis, which are associated with the expression of Bcl-2, Bax, and caspase-3. A HFD also increased the expression levels of PCSK9 and BACE1. BACE1 promotes cleavage of amyloid precursor proteins to generate β-amyloid peptide (Aβ), which induces neuronal apoptosis. Protein levels of Aβ are associated with the observation of amyloid plaques in the hippocampus of the HFD group. The results suggest that hyperlipidemia regulates neuronal apoptosis by increasing PCSK9 and BACE1 expression. Overall, the current study may elucidate the role of lipid metabolism disorder in AD pathogenesis.

The Effects of Long-Term Saturated Fat Enriched Diets on the Brain Lipidome

The brain is highly enriched in lipids, where they influence neurotransmission, synaptic plasticity and inflammation. Non-pathological modulation of the brain lipidome has not been previously reported and few studies have investigated the interplay between plasma lipid homeostasis relative to cerebral lipids. This study explored whether changes in plasma lipids induced by chronic consumption of a well-tolerated diet enriched in saturated fatty acids (SFA) was associated with parallel changes in cerebral lipid homeostasis. Male C57Bl/6 mice were fed regular chow or the SFA diet for six months. Plasma, hippocampus (HPF) and cerebral cortex (CTX) lipids were analysed by LC-ESI-MS/MS. A total of 348 lipid species were determined, comprising 25 lipid classes. The general abundance of HPF and CTX lipids was comparable in SFA fed mice versus controls, despite substantial differences in plasma lipid-class abundance. However, significant differences in 50 specific lipid species were identified as a consequence of SFA treatment, restricted to phosphatidylcholine (PC), phosphatidylethanolamine (PE), alkyl-PC, alkenyl-PC, alkyl-PE, alkenyl-PE, cholesterol ester (CE), diacylglycerol (DG), phosphatidylinositol (PI) and phosphatidylserine (PS) classes. Partial least squares regression of the HPF/CTX lipidome versus plasma lipidome revealed the plasma lipidome could account for a substantial proportion of variation. The findings demonstrate that cerebral abundance of specific lipid species is strongly associated with plasma lipid homeostasis.

GGIP: Structure and sequence-based GPCR-GPCR interaction pair predictor

G Protein-Coupled Receptors (GPCRs) are important pharmaceutical targets. More than 30% of currently marketed pharmaceutical medicines target GPCRs. Numerous studies have reported that GPCRs function not only as monomers but also as homo- or hetero-dimers or higher-order molecular complexes. Many GPCRs exert a wide variety of molecular functions by forming specific combinations of GPCR subtypes. In addition, some GPCRs are reportedly associated with diseases. GPCR oligomerization is now recognized as an important event in various biological phenomena, and many researchers are investigating this subject. We have developed a support vector machine (SVM)-based method to predict interacting pairs for GPCR oligomerization, by integrating the structure and sequence information of GPCRs. The performance of our method was evaluated by the Receiver Operating Characteristic (ROC) curve. The corresponding area under the curve was 0.938. As far as we know, this is the only prediction method for interacting pairs among GPCRs. Our method could accelerate the analyses of these interactions, and contribute to the elucidation of the global structures of the GPCR networks in membranes. Proteins 2016; 84:1224-1233. © 2016 Wiley Periodicals, Inc.

Experimental Periodontitis Results in Prediabetes and Metabolic Alterations in Brain, Liver and Heart: Global Untargeted Metabolomic Analyses

Results from epidemiological studies suggest that there is an association between periodontitis and prediabetes, however, causality is not known. The results from our previous studies suggest that induction of periodontitis leads to hyperinsulinemia glucose intolerance and insulin resistance, all hallmarks of prediabetes. However, global effects of periodontitis on critical organs in terms of metabolic alterations are unknown. We determined the metabolic effects of periodontitis on brain, liver, heart and plasma resulting from Porphyromonas gingivalis induced periodontitis in mice. Periodontitis was induced by oral application of the periodontal pathogen, Porphyromonas gingivalis for 22 weeks. Global untargeted biochemical profiles in samples from these organs/plasma were determined by liquid and gas chromatography/mass spectrometry and compared between controls and animals with periodontitis. Oral application of Porphyromonas gingivalis induced chronic periodontitis and hallmarks of prediabetes. The results of sample analyses indicated a number of changes in metabolic readouts, including changes in metabolites related to glucose and arginine metabolism, inflammation and redox homeostasis. Changes in biochemicals suggested subtle systemic effects related to periodontal disease, with increases in markers of inflammation and oxidative stress most prominent in the liver. Signs of changes in redox homeostasis were also seen in the brain and heart. Elevated bile acids in liver were suggestive of increased biosynthesis, which may reflect changes in liver function. Interestingly, signs of decreasing glucose availability were seen in the brain. In all three organs and plasma, there was a significant increase in the microbiome-derived bioactive metabolite 4-ethylphenylsulfate sulfate in animals with periodontitis. The results of metabolic profiling suggest that periodontitis/bacterial products alter metabolomic signatures of brain, heart, liver, and plasma in the prediabetic state. These data provide scientific community valuable metabolic signatures that become the basis for understanding the impact of periodontitis on a systemic disease and potentially targets for therapeutic intervention.

Short-term exposure to a diet high in fat and sugar, or liquid sugar, selectively impairs hippocampal-dependent memory, with differential impacts on inflammation

Chronic high-energy diets are known to induce obesity and impair memory; these changes have been associated with inflammation in brain areas crucial for memory. In this study, we investigated whether inflammation could also be related to diet-induced memory deficits, prior to obesity. We exposed rats to chow, chow supplemented with a 10% sucrose solution (Sugar) or a diet high in fat and sugar (Caf+Sugar) and assessed hippocampal-dependent and perirhinal-dependent memory at 1 week. Both high-energy diet groups displayed similar, selective hippocampal-dependent memory deficits despite the Caf+Sugar rats consuming 4-5 times more energy, and weighing significantly more than the other groups. Extreme weight gain and excessive energy intake are therefore not necessary for deficits in memory. Weight gain across the diet period however, was correlated with the memory deficits, even in the Chow rats. The Sugar rats had elevated expression of a number of inflammatory genes in the hippocampus and WAT compared to Chow and Caf+Sugar rats but not in the perirhinal cortex or hypothalamus. Blood glucose concentrations were also elevated in the Sugar rats, and were correlated with the hippocampal inflammatory markers. Together, these results indicate that liquid sugar can rapidly elevate markers of central and peripheral inflammation, in association with hyperglycemia, and this may be related to the memory deficits in the Sugar rats.

Health-related quality of life among veterans in addictions treatment: identifying behavioral targets for future intervention

BACKGROUND

US veterans report lower health-related quality of life (HRQoL) relative to the general population. Identifying behavioral factors related to HRQoL that are malleable to change may inform interventions to improve well-being in this vulnerable group.

PURPOSE

The current study sought to characterize HRQoL in a largely male sample of veterans in addictions treatment, both in relation to US norms and in association with five recommended health behavior practices: regularly exercising, managing stress, having good sleep hygiene, consuming fruits and vegetables, and being tobacco free.

METHODS

We assessed HRQoL with 250 veterans in addictions treatment (96 % male, mean age 53, range 24-77) using scales from four validated measures. Data reduction methods identified two principal components reflecting physical and mental HRQoL. Model testing of HRQoL associations with health behaviors adjusted for relevant demographic and treatment-related covariates.

RESULTS

Compared to US norms, the sample had lower HRQoL scores. Better psychological HRQoL was associated with higher subjective social standing, absence of pain or trauma, lower alcohol severity, and monotonically with the sum of health behaviors (all p < 0.05). Specifically, psychological HRQoL was associated with regular exercise, stress management, and sleep hygiene. Regular exercise also related to better physical HRQoL. The models explained >40 % of the variance in HRQoL.

CONCLUSIONS

Exercise, sleep hygiene, and stress management are strongly associated with HRQoL among veterans in addictions treatment. Future research is needed to test the effect of interventions for improving well-being in this high-risk group.

Neuroprotective effects of metformin against Aβ-mediated inhibition of long-term potentiation in rats fed a high-fat diet

Metformin (Met) is used to treat neurodegenerative disorders such as Alzheimer's disease (AD). Conversely, high-fat diets (HFD) have been shown to increase AD risk. In this study, we investigated the neuroprotective effects of Met on β-amyloid (Aβ)-induced impairments in hippocampal synaptic plasticity in AD model rats that were fed a HFD. In this study, 32 adult male Wistar rats were randomly assigned to four groups: group I (control group, regular diet); group II (HFD+vehicle); group III (HFD+Aβ); or group IV (Met+HFD+Aβ). Rats fed a HFD were injected with Aβ to induce AD, allowed to recover, and treated with Met for 8 weeks. The rats were then anesthetized with intraperitoneal injections of urethane and placed in a stereotaxic apparatus for surgery, electrode implantation, and field potential recording. In vivo electrophysiological recordings were then performed to measure population spike (PS) amplitude and excitatory postsynaptic potential (EPSP) slope in the hippocampal dentate gyrus. Long-term potentiation (LTP) was induced by high-frequency stimulation of the perforant pathway. Blood samples were then collected to measure plasma levels of triglycerides, low-density lipoproteins, very low-density lipoprotein, and cholesterol. After induction of LTP, PS amplitude and EPSP slope were significantly decreased in Aβ-injected rats fed a HFD compared to vehicle-injected animals or untreated animals that were fed a normal diet. Met treatment of Aβ-injected rats significantly attenuated these decreases, suggesting that Met decreased the effects of Aβ on LTP. These findings suggest that Met treatment is neuroprotective against the detrimental effects of Aβ and HFDs on hippocampal synaptic plasticity.

Thidoredxin-2 overexpression fails to rescue chronic high calorie diet induced hippocampal dysfunction

A high calorie diet (HCD) can impair hippocampal synaptic plasticity and cognitive function in animal models. Mitochondrial thioredoxin 2 (TRX-2) is critical for maintaining intracellular redox status, but whether it can protect against HCD-induced impairment of synaptic plasticity is unknown. We found that levels of TRX-2 are reduced in the hippocampus of wild type mice maintained for 8 months on a HCD, and that the mice on the HCD exhibit impaired hippocampal synaptic plasticity (long-term potentiation at CA1 synapses) and cognitive function (novel object recognition). Transgenic mice overexpressing human TRX-2 (hTRX-2) exhibit increased resistance to diquat-induced oxidative stress in peripheral tissues. However, neither the HCD nor hTRX-2 overexpression affected levels of lipid peroxidation products (F2 isoprostanes) in the hippocampus, and hTRX-2 transgenic mice were not protected against the adverse effects of the HCD on hippocampal synaptic plasticity and cognitive function. Our findings indicate that TRX-2 overexpression does not mitigate adverse effects of a HCD on synaptic plasticity, and also suggest that oxidative stress may not be a pivotal factor in the impairment of synaptic plasticity and cognitive function caused by HCDs.

Dietary cholesterol concentration affects synaptic plasticity and dendrite spine morphology of rabbit hippocampal neurons

Previous studies have shown dietary cholesterol can enhance learning but retard memory which may be partly due to increased cholesterol levels in hippocampus and reduced afterhyperpolarization (AHP) amplitude of hippocampal CA1 neurons. This study explored the dose-dependent effect of dietary cholesterol on synaptic plasticity of rabbit hippocampal CA1 neurons and spine morphology, the postsynaptic structures responsible for synaptic plasticity. Field potential recordings revealed a low concentration of dietary cholesterol increased long-term potentiation (LTP) expression while high concentrations produced a pronounced reduction in LTP expression. Dietary cholesterol facilitated basal synaptic transmission but did not influence presynaptic function. DiI staining showed dietary cholesterol induced alterations in dendrite spine morphology characterized by increased mushroom spine density and decreased thin spine density, two kinds of dendritic spines that may be linked to memory consolidation and learning acquisition. Dietary cholesterol also modulated the geometric measures of mushroom spines. Therefore, dietary cholesterol dose-dependently modulated both synaptic plasticity and dendrite spine morphologies of hippocampal CA1 neurons that could mediate learning and memory changes previously seen to result from feeding a cholesterol diet.

Ceramides in Alzheimer's Disease: Key Mediators of Neuronal Apoptosis Induced by Oxidative Stress and Aβ Accumulation

Alzheimer's disease (AD), the most common chronic and progressive neurodegenerative disorder, is characterized by extracellular deposits of amyloid β-peptides (Aβ) and intracellular deposits of hyperphosphorylated tau (phospho-tau) protein. Ceramides, the major molecules of sphingolipid metabolism and lipid second messengers, have been associated with AD progression and pathology via Aβ generation. Enhanced levels of ceramides directly increase Aβ through stabilization of β-secretase, the key enzyme in the amyloidogenic processing of Aβ precursor protein (APP). As a positive feedback loop, the generated oligomeric and fibrillar Aβ induces a further increase in ceramide levels by activating sphingomyelinases that catalyze the catabolic breakdown of sphingomyelin to ceramide. Evidence also supports important role of ceramides in neuronal apoptosis. Ceramides may initiate a cascade of biochemical alterations, which ultimately leads to neuronal death by diverse mechanisms, including depolarization and permeabilization of mitochondria, increased production of reactive oxygen species (ROS), cytochrome c release, Bcl-2 depletion, and caspase-3 activation, mainly by modulating intracellular signalling, particularly along the pathways related to Akt/PKB kinase and mitogen-activated protein kinases (MAPKs). This review summarizes recent findings related to the role of ceramides in oxidative stress-driven neuronal apoptosis and interplay with Aβ in the cascade of events ending in neuronal degeneration.