Fish oil supplementation alleviates metabolic and anxiodepressive effects of diet-induced obesity and associated changes in brain lipid composition in mice

Aging AdipoR2-deficient mice are hyperactive with enlarged brains excessively rich in saturated fatty acids

To investigate how the fatty acid composition of brain phospholipids influences brain-specific processes, we leveraged the AdipoR2 (adiponectin receptor 2) knockout mouse model in which the brain is enlarged, and cellular membranes are excessively rich in saturated fatty acids. Lipidomics analysis of brains at 2, 7, and 18 months of age showed that phosphatidylcholines, which make up about two-thirds of all cerebrum membrane lipids, contain a gross excess of saturated fatty acids in AdipoR2 knockout mice, and that this is mostly attributed to an excess palmitic acid (C16:0) at the expense of oleic acid (C18:1), consistent with a defect in fatty acid desaturation and elongation in the mutant. Specifically, there was a ~12% increase in the overall saturated fatty acid content within phosphatidylcholines and a ~30% increase in phosphatidylcholines containing two palmitic acids. Phosphatidylethanolamines, sphingomyelins, ceramides, lactosylceramides, and dihydroceramides also showed an excess of saturated fatty acids in the AdipoR2 knockout mice while nervonic acid (C24:1) was enriched at the expense of shorter saturated fatty acids in glyceroceramides. Similar defects were found in the cerebellum and myelin sheaths. Histology showed that cell density is lower in the cerebrum of AdipoR2 knockout mice, but electron microscopy did not detect reproducible defects in the ultrastructure of cerebrum neurons, though proteomics analysis showed an enrichment of electron transport chain proteins in the cerebellum. Behavioral tests showed that older (33 weeks old) AdipoR2 knockout mice are hyperactive and anxious compared to control mice of a similar age. Also, in contrast to control mice, the AdipoR2 knockout mice do not gain weight in old age but do have normal lifespans. We conclude that an excess fatty acid saturation in brain phospholipids is accompanied by hyperactivity but seems otherwise well tolerated.

Obesity and the cerebral cortex: Underlying neurobiology in mice and humans

Obesity is a major modifiable risk factor for Alzheimer's disease (AD), characterized by progressive atrophy of the cerebral cortex. The neurobiology of obesity contributions to AD is poorly understood. Here we show with in vivo MRI that diet-induced obesity decreases cortical volume in mice, and that higher body adiposity associates with lower cortical volume in humans. Single-nuclei transcriptomics of the mouse cortex reveals that dietary obesity promotes an array of neuron-adverse transcriptional dysregulations, which are mediated by an interplay of excitatory neurons and glial cells, and which involve microglial activation and lowered neuronal capacity for neuritogenesis and maintenance of membrane potential. The transcriptional dysregulations of microglia, more than of other cell types, are like those in AD, as assessed with single-nuclei cortical transcriptomics in a mouse model of AD and two sets of human donors with the disease. Serial two-photon tomography of microglia demonstrates microgliosis throughout the mouse cortex. The spatial pattern of adiposity-cortical volume associations in human cohorts interrogated together with in silico bulk and single-nucleus transcriptomic data from the human cortex implicated microglia (along with other glial cells and subtypes of excitatory neurons), and it correlated positively with the spatial profile of cortical atrophy in patients with mild cognitive impairment and AD. Thus, multi-cell neuron-adverse dysregulations likely contribute to the loss of cortical tissue in obesity. The dysregulations of microglia may be pivotal to the obesity-related risk of AD.

Neurolipidomic Insights into Anxiety Disorders: Uncovering Lipid Dynamics for Potential Therapeutic Advances

Anxiety disorders constitute a spectrum of psychological conditions affecting millions of individuals worldwide, imposing a significant health burden. Historically, the development of anxiolytic medications has been largely focused on neurotransmitter function and modulation. However, in recent years, neurolipids emerged as a prime target for understanding psychiatric pathogenesis and developing novel medications. Neurolipids influence various neural activities such as neurotransmission and cellular functioning, as well as maintaining cell membrane integrity. Therefore, this review aims to elucidate the alterations in neurolipids associated with an anxious mental state and explore their potential as targets of novel anxiolytic medications. Existing evidence tentatively associates dysregulated neurolipid levels with the etiopathology of anxiety disorders. Notably, preclinical investigations suggest that several neurolipids, including endocannabinoids and polyunsaturated fatty acids, may hold promise as potential pharmacological targets. Overall, the current literature tentatively suggests the involvement of lipids in the pathogenesis of anxiety disorders, hinting at potential prospects for future pharmacological interventions.

Dietary linoleic acid supplementation protects against obesity-induced microglial reactivity in mice

We investigated whether linoleic acid (LA) supplementation could modulate emotional behavior and microglia-related neuroinflammation. For that, male mice of C57BL/6J genetic background fed either a high-fat diet (HFD) or a standard diet (STD) for 12 weeks, were treated with a vehicle or LA solution for 5 weeks before being evaluated for emotional behavior using a battery of behavioral tests. The animals were subsequently sacrificed and their brains collected and processed for immunofluorescence staining, targeting microglia-specific calcium-binding proteins (IBA-1). Neuroinflammation severity was assessed in multiple hypothalamic, cortical and subcortical brain regions. We show an anxio-depressive-like effect of sustained HFD feeding that was neither alleviated nor worsened with LA supplementation. However, increased IBA-1 expression and microgliosis in the HFD group were largely attenuated by LA supplementation. These observations demonstrate that the anti-neuroinflammatory properties of LA are not restricted to hypothalamic areas but are also evident at the cortical and subcortical levels. This study discloses that neuroinflammation plays a role in the genesis of neuropsychiatric disorders in the context of obesity, and that LA supplementation is a useful dietary strategy to alleviate the impact of obesity-related neuroinflammation.

Dietary fatty acid composition drives neuroinflammation and impaired behavior in obesity

Nutrient composition in obesogenic diets may influence the severity of disorders associated with obesity such as insulin-resistance and chronic inflammation. Here we hypothesized that obesogenic diets rich in fat and varying in fatty acid composition, particularly in omega 6 (ω6) to omega 3 (ω3) ratio, have various effects on energy metabolism, neuroinflammation and behavior. Mice were fed either a control diet or a high fat diet (HFD) containing either low (LO), medium (ME) or high (HI) ω6/ω3 ratio. Mice from the HFD-LO group consumed less calories and exhibited less body weight gain compared to other HFD groups. Both HFD-ME and HFD-HI impaired glucose metabolism while HFD-LO partly prevented insulin intolerance and was associated with normal leptin levels despite higher subcutaneous and perigonadal adiposity. Only HFD-HI increased anxiety and impaired spatial memory, together with increased inflammation in the hypothalamus and hippocampus. Our results show that impaired glucose metabolism and neuroinflammation are uncoupled, and support that diets with a high ω6/ω3 ratio are associated with neuroinflammation and the behavioral deterioration coupled with the consumption of diets rich in fat.

High-Fat Diets in Animal Models of Alzheimer's Disease: How Can Eating Too Much Fat Increase Alzheimer's Disease Risk?

High dietary intake of saturated fatty acids is a suspected risk factor for neurodegenerative diseases, including Alzheimer's disease (AD). To decipher the causal link behind these associations, high-fat diets (HFD) have been repeatedly investigated in animal models. Preclinical studies allow full control over dietary composition, avoiding ethical concerns in clinical trials. The goal of the present article is to provide a narrative review of reports on HFD in animal models of AD. Eligibility criteria included mouse models of AD fed a HFD defined as > 35% of fat/weight and western diets containing > 1% cholesterol or > 15% sugar. MEDLINE and Embase databases were searched from 1946 to August 2022, and 32 preclinical studies were included in the review. HFD-induced obesity and metabolic disturbances such as insulin resistance and glucose intolerance have been replicated in most studies, but with methodological variability. Most studies have found an aggravating effect of HFD on brain Aβ pathology, whereas tau pathology has been much less studied, and results are more equivocal. While most reports show HFD-induced impairment on cognitive behavior, confounding factors may blur their interpretation. In summary, despite conflicting results, exposing rodents to diets highly enriched in saturated fat induces not only metabolic defects, but also cognitive impairment often accompanied by aggravated neuropathological markers, most notably Aβ burden. Although there are important variations between methods, particularly the lack of diet characterization, these studies collectively suggest that excessive intake of saturated fat should be avoided in order to lower the incidence of AD.

Central activation of the fatty acid sensor GPR120 suppresses microglia reactivity and alleviates sickness- and anxiety-like behaviors

G protein-coupled receptor 120 (GPR120, Ffar4) is a sensor for long-chain fatty acids including omega-3 polyunsaturated fatty acids (n-3 PUFAs) known for beneficial effects on inflammation, metabolism, and mood. GPR120 mediates the anti-inflammatory and insulin-sensitizing effects of n-3 PUFAs in peripheral tissues. The aim of this study was to determine the impact of GPR120 stimulation on microglial reactivity, neuroinflammation and sickness- and anxiety-like behaviors by acute proinflammatory insults. We found GPR120 mRNA to be enriched in  both murine and human microglia, and in situ hybridization revealed GPR120 expression in microglia of the nucleus accumbens (NAc) in mice. In a manner similar to or exceeding n-3 PUFAs, GPR120 agonism (Compound A, CpdA) strongly attenuated lipopolysaccharide (LPS)-induced proinflammatory marker expression in primary mouse microglia, including tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), and inhibited nuclear factor-ĸB translocation to the nucleus. Central administration of CpdA to adult mice blunted LPS-induced hypolocomotion and anxiety-like behavior and reduced TNF-α, IL-1β and IBA-1 (microglia marker) mRNA in the NAc, a brain region modulating anxiety and motivation and implicated in neuroinflammation-induced mood deficits. GPR120 agonist pre-treatment attenuated NAc microglia reactivity and alleviated sickness-like behaviors elicited by central injection TNF-α and IL-1β. These findings suggest that microglial GPR120 contributes to neuroimmune regulation and behavioral changes in response to acute infection and elevated brain cytokines. GPR120 may participate in the protective action of n-3 PUFAs at the neural and behavioral level and offers potential as treatment target for neuroinflammatory conditions.

Multi-omics reveal neuroprotection of Acer truncatum Bunge Seed extract on hypoxic-ischemia encephalopathy rats under high-altitude

Hypoxic-ischemic encephalopathy (HIE) at high-altitudes leads to neonatal mortality and long-term neurological complications without effective treatment. Acer truncatum Bunge Seed extract (ASO) is reported to have effect on cognitive improvement, but its molecular mechanisms on HIE are unclear. In this study, ASO administration contributed to reduced neuronal cell edema and improved motor ability in HIE rats at a simulated 4500-meter altitude. Transcriptomics and WGCNA analysis showed genes associated with lipid biosynthesis, redox homeostasis, neuronal growth, and synaptic plasticity regulated in the ASO group. Targeted and untargeted-lipidomics revealed decreased free fatty acids and increased phospholipids with favorable ω-3/ω-6/ω-9 fatty acid ratios, as well as reduced oxidized glycerophospholipids (OxGPs) in the ASO group. Combining multi-omics analysis demonstrated FA to FA-CoA, phospholipids metabolism, and lipid peroxidation were regulated by ASO treatment. Our results illuminated preliminary metabolism mechanism of ASO ingesting in rats, implying ASO administration as potential intervention strategy for HIE under high-altitude.

Effects of diabetes on microglial physiology: a systematic review of in vitro, preclinical and clinical studies

Diabetes mellitus is a heterogeneous chronic metabolic disorder characterized by the presence of hyperglycemia, commonly preceded by a prediabetic state. The excess of blood glucose can damage multiple organs, including the brain. In fact, cognitive decline and dementia are increasingly being recognized as important comorbidities of diabetes. Despite the largely consistent link between diabetes and dementia, the underlying causes of neurodegeneration in diabetic patients remain to be elucidated. A common factor for almost all neurological disorders is neuroinflammation, a complex inflammatory process in the central nervous system for the most part orchestrated by microglial cells, the main representatives of the immune system in the brain. In this context, our research question aimed to understand how diabetes affects brain and/or retinal microglia physiology. We conducted a systematic search in PubMed and Web of Science to identify research items addressing the effects of diabetes on microglial phenotypic modulation, including critical neuroinflammatory mediators and their pathways. The literature search yielded 1327 records, including 18 patents. Based on the title and abstracts, 830 papers were screened from which 250 primary research papers met the eligibility criteria (original research articles with patients or with a strict diabetes model without comorbidities, that included direct data about microglia in the brain or retina), and 17 additional research papers were included through forward and backward citations, resulting in a total of 267 primary research articles included in the scoping systematic review. We reviewed all primary publications investigating the effects of diabetes and/or its main pathophysiological traits on microglia, including in vitro studies, preclinical models of diabetes and clinical studies on diabetic patients. Although a strict classification of microglia remains elusive given their capacity to adapt to the environment and their morphological, ultrastructural and molecular dynamism, diabetes modulates microglial phenotypic states, triggering specific responses that include upregulation of activity markers (such as Iba1, CD11b, CD68, MHC-II and F4/80), morphological shift to amoeboid shape, secretion of a wide variety of cytokines and chemokines, metabolic reprogramming and generalized increase of oxidative stress. Pathways commonly activated by diabetes-related conditions include NF-κB, NLRP3 inflammasome, fractalkine/CX3CR1, MAPKs, AGEs/RAGE and Akt/mTOR. Altogether, the detailed portrait of complex interactions between diabetes and microglia physiology presented here can be regarded as an important starting point for future research focused on the microglia-metabolism interface.

Impact of cafeteria diet and n3 supplementation on the intestinal microbiota, fatty acids levels, neuroinflammatory markers and social memory in male rats

OBJECTIVE

To assess the effects of omega-3 (n3) supplementation on intestinal microbiota, fatty acids profile, neuroinflammation, and social memory of cafeteria diet (CAF)-fed rats.

METHODS

Male Wistar rats were fed with CAF for 20 weeks. Omega-3 (500 mg/kg/day) was supplemented between the 16th and 20th week. Colon morphology, intestinal microbiota composition, short-chain fatty acids (SCFA) and lipopolysaccharide (LPS) in the plasma, fatty acids profile, TLR-4 and claudin-5 expressions in the brain, and social memory were investigated.

RESULTS

CAF reduced colon length, crypts' depth, and microbiota diversity, while n3 increased the Firmicutes/Bacteroidetes ratio. CAF increased SCFA plasma levels, but n3 reduced butyrate and isobutyrate in obese rats. LPS was increased in CAF-fed rats, and n3 decreased its levels. In the cerebral cortex, n3 increased caprylic, palmitic, stearic, tricosanoic, lignoceric, myristoleic, and linoleic acids. CAF increased palmitic acid and TLR-4 expression in the cerebral cortex while decreasing claudin-5 in the hippocampus. In the social memory test, CAF-fed animals showed greater social interaction with no effect of n3.

CONCLUSIONS

The lack of n3 effect in some of the evaluated parameters may be due to the severity of the obesity caused by CAF. However, n3 reduced LPS levels, suggesting its ability to reverse endotoxemia.

Administration Time and Dietary Patterns Modified the Effect of Inulin on CUMS-Induced Anxiety and Depression

SCOPE

Prebiotics exert anxiolytic and antidepressant effects through the microbiota-gut-brain axis in animal models. However, the influence of prebiotic administration time and dietary pattern on stress-induced anxiety and depression is unclear. In this study, whether administration time can modify the effect of inulin on mental disorders within normal and high-fat diets are investigated.

METHODS AND RESULTS

Mice subjected to chronic unpredicted mild stress (CUMS) are administered with inulin in the morning (7:30-8:00 am) or evening (7:30-8:00 pm) for 12 weeks. Behavior, intestinal microbiome, cecal short-chain fatty acids, neuroinflammatory responses, and neurotransmitters are measured. A high-fat diet aggravated neuroinflammation and is more likely to induce anxiety and depression-like behavior (p < 0.05). Morning inulin treatment improves the exploratory behavior and sucrose preference better (p < 0.05). Both inulin treatments decrease the neuroinflammatory response (p < 0.05), with a more evident trend for the evening administration. Furthermore, morning administration tends to affect the brain-derived neurotrophic factor and neurotransmitters.

CONCLUSION

Administration time and dietary patterns seem to modify the effect of inulin on anxiety and depression. These results provide a basis for assessing the interaction of administration time and dietary patterns, providing guidance for the precise regulation of dietary prebiotics in neuropsychiatric disorders.

Effects of a Diet Containing Sources of Prebiotics and Probiotics and Modification of the Gut Microbiota on the Reduction of Body Fat

In 2022, according to the World Health Organization (WHO) report, overweight and obesity have reached epidemic proportions in the WHO European Region, affecting almost 60% of adults. Based on the assessment of BMI (Body Mass Index), a group of 56 women aged 25-45 years (31 women group A average BMI 34.9 ± 4.86 kg/m2 and 25 women group B average BMI 33.4 ± 4.02 kg/m2) were qualified for the study. In a multi-center, two-arm, parallel, non-randomized study, two types of weight-reduction diets (A and B) were used over a 3-month period. In group A, a standard low-energy diet was used with individually adjusted caloric intake of 1100-1300 kcal, with an increase in the amount and frequency of consumption of sauerkraut and groats and a daily intake of fermented milk drinks (300-400 g), fermented cucumbers (100 g), mineral water (1 L) and cod liver oil (5 mL). In group B, a standard low-energy diet with individually adjusted caloric intake of 1100-1300 kcal with daily intake of fermented milk products (150 g), highly mineralized water (0.5 L), once a week fermented cucumbers, and once a week buckwheat groats was used. The following measurements were taken: body weight, body fat mass, water content, body height, waist circumference, and hip circumference. Body weight and body composition were measured using the Tanita MC-780 MA and TANITA BC-601 analyzer using the bioelectric bioimpedance method. The stool samples were analyzed in the microbiology laboratory where quantification of Bifidobcaterium spp., Bacteroides spp., Faecalibacterium prausnitzii species, Akkermansia muciniphila and total bacterial count (TBC) was performed. Under the influence of the introduced nutritional intervention, a statistically significant reduction in body weight, body fat, waist circumference, and hip circumference was demonstrated after 3 months. Under the influence of weight reduction, as well as dietary changes, there was an increase in the number of Akkermansia muciniphila bacteria in the women studied. The low-energy diet containing sources of natural prebiotics and probiotics had a more favorable effect on the number of Faecalibacterium prausnitzii bacteria compared to the standard diet.

The relationship between n-3 polyunsaturated fatty acids and telomere: A review on proposed nutritional treatment against metabolic syndrome and potential signaling pathways

Metabolic syndrome (MetS), a cluster of metabolic abnormalities composed of central obesity, elevated blood pressure, glucose disturbances, hypercholesterolemia and dyslipidaemia, has increasingly become a public health problem in the 21st century worldwide. The dysfunction of telomeres, the repetitive DNA with highly conserved sequences (5'-TTAGGG-3'), is remarkably correlated with organismal aging, even suggesting a causal relationship with metabolic disorders. The health benefits of n-3 polyunsaturated fatty acids (PUFAs) in multiple disorders are associated with telomere length in evidence, which have recently drawn wide attention. However, functional targets and pathways for the associations of n-3 PUFAs and telomere with MetS remain scare. Few studies have summarized the role of n-3 PUFAs in DNA damage repair pathways, anti-inflammatory pathways, and redox balance, linking with telomere biology, and other potential telomere-related signaling pathways. This review aims to (i) elucidate how n-3 PUFAs ameliorate telomere attrition in the context of anti-oxidation and anti-inflammation; (ii) unravel the role of n-3 PUFAs in modulating telomere-related neuron dysfunction and regulating the neuro-endocrine-immunological network in MetS; (iii) epidemiologically implicate the associations of metabolic disorders and n-3 PUFAs with telomere length; and (iv) suggest promising biochemical approaches and advancing methodologies to overcome the inter-variation problem helpful for future research.

Neuroepigenetic Changes in DNA Methylation Affecting Diabetes-Induced Cognitive Impairment

Chronic diabetic conditions have been associated with certain cerebral complications, that include neurobehavioral dysfunctional patterns and morphological alterations of neurons, especially the hippocampus. Neuroanatomical studies done by the authors have shown decreased total dendritic length, intersections, dendritic length per branch order and nodes in the CA1 hippocampal region of the diabetic brain as compared to its normal control group, indicating reduced dendritic arborization of the hippocampal CA1 neurons. Epigenetic alterations in the brain are well known to affect age-associated disorders, however its association with the evolving diabetes-induced damage in the brain is still not fully understood. DNA hypermethylation within the neurons, tend to silent the gene expression of several regulatory proteins. The findings in the study have shown an increase in global DNA methylation in palmitic acid-induced lipotoxic Neuro-2a cells as well as within the diabetic mice brain. Inhibiting DNA methylation, restored the levels of HSF1 and certain HSPs, suggesting plausible effect of DNMTs in maintaining the proteostasis and synaptic fidelity. Neuroinflammation, as exhibited by the astrocyte activation (GFAP), were further significantly decreased in the 5-azadeoxycytidine group (DNMT inhibitor). This was further evidenced by decrease in proinflammatory cytokines TNF⍺, IL-6, and mediators iNOS and Phospho-NFkB. Our results suggest that changes in DNA methylation advocate epigenetic dysregulation and its involvement in disrupting the synaptic exactitude in the hippocampus of diabetic mice model, providing an insight into the pathophysiology of diabetes-induced neuroepigenetic changes.

Zinc Supplementation Partially Decreases the Harmful Effects of a Cafeteria Diet in Rats but Does Not Prevent Intestinal Dysbiosis

Zinc (Zn) plays an important role in metabolic homeostasis and may modulate neurological impairment related to obesity. The present study aimed to evaluate the effect of Zn supplementation on the intestinal microbiota, fatty acid profile, and neurofunctional parameters in obese male Wistar rats. Rats were fed a cafeteria diet (CAF), composed of ultra-processed and highly caloric and palatable foods, for 20 weeks to induce obesity. From week 16, Zn supplementation was started (10 mg/kg/day). At the end of the experiment, we evaluated the colon morphology, composition of gut microbiota, intestinal fatty acids, integrity of the intestinal barrier and blood-brain barrier (BBB), and neuroplasticity markers in the cerebral cortex and hippocampus. Obese rats showed dysbiosis, morphological changes, short-chain fatty acid (SCFA) reduction, and increased saturated fatty acids in the colon. BBB may also be compromised in CAF-fed animals, as claudin-5 expression is reduced in the cerebral cortex. In addition, synaptophysin was decreased in the hippocampus, which may affect synaptic function. Our findings showed that Zn could not protect obese animals from intestinal dysbiosis. However, an increase in acetate levels was observed, which suggests a partial beneficial effect of Zn. Thus, Zn supplementation may not be sufficient to protect from obesity-related dysfunctions.

DHA/EPA supplementation decreases anxiety-like behaviour, but it does not ameliorate metabolic profile in obese male rats

Obesity is a major public health problem that predisposes to several diseases and higher mortality in patients with COVID-19. Obesity also generates neuroinflammation, which predisposes to the development of neuropsychiatric diseases. Since there is a lack of effective treatments for obesity, the search for new strategies to reverse its consequences is urgent. In this perspective, the anti-inflammatory properties of omega-3 polyunsaturated fatty acids such as DHA/EPA might reduce the harmful effects of obesity. Here, we used the cafeteria diet (CAF) model to induce obesity in Wistar rats. Animals received ultra-processed food for 20 weeks, and DHA/EPA supplementation (500 mg/kg per d) was performed between the 16th and the 20th week. At the end of the experiment, it was evaluated: body weight, visceral fat deposition, plasma glucose, insulin and triglycerides, and it was also measured the levels of inflammatory cytokines TNF-α and IL-6 in plasma and liver, and TNF-α in the prefrontal cortex. The elevated plus maze test was performed to analyse anxiety-like behaviour. Our results demonstrated that DHA/EPA could not reverse weight and fat gain and did not modify plasma dosages. However, there was a decrease in IL-6 in the liver (DHA/EPA effect: P = 0.023) and TNF-α in the brain (CAF compared with CAF + DHA/EPA, P < 0.05). Also, there was a decrease in the anxiety index in CAF + DHA/EPA compared with the CAF group (P < 0.01). Thus, DHA/EPA supplementation is helpful to reverse the consequences of obesity in the brain.

The menace of obesity to depression and anxiety prevalence

The incidence of depression and anxiety is amplified by obesity. Mounting evidence reveals that the psychiatric consequences of obesity stem from poor diet, inactivity, and visceral adipose accumulation. Resulting metabolic and vascular dysfunction, including inflammation, insulin and leptin resistance, and hypertension, have emerged as key risks to depression and anxiety development. Recent research advancements are exposing the important contribution of these different corollaries of obesity and their impact on neuroimmune status and the neural circuits controlling mood and emotional states. Along these lines, this review connects the clinical manifestations of depression and anxiety in obesity to our current understanding of the origins and biology of immunometabolic threats to central nervous system function and behavior.

Supplementation of EPA and DHA in pregnant women with type 1 diabetes mellitus

BACKGROUND/OBJECTIVE

Lower proportions of n-3 PUFAs have been observed in neonates born to diabetic mothers. We aimed to investigate the association between DHA and EPA supplementation during pregnancy complicated with type 1 diabetes on concentration and proportion of fatty acids in maternal and foetal blood.

SUBJECTS AND METHODS

We conducted a prospective randomized, single-blinded, placebo-controlled trial of 111 eligible pregnant women with type 1 diabetes and presented the results of 84 (intervention arm and control arm comprised 42 participants each) of them who successfully finished the trial in an academic hospital. The initiation of EPA and DHA supplementation or placebo started at randomization visit on gestational week 11-12. Blood samples were taken on the first (screening) visit to the clinic (1st trimester, between 8th and 10th gestational week, GW), then in the second trimester (19-24th GW) and third trimester (30th-33rd GW). On the delivery day, a blood sample was taken on fasting just before birth. The umbilical vein blood sample was taken shortly after the delivery.

RESULTS

We found a significant increase in the intervention group when compared the first and the third trimester for n-3 PUFAs concentration, 4.3 mg/L (3.3-7.6): 10.0 mg/L (7.1-13.7), p < .001. In the intervention group, the concentration of DHA in maternal vein serum was 11.4 mg/L (7.7-17.5), and in umbilical vein serum, it was 5.1 mg/L (3.0-7.7), which was significantly higher than that in the control group, maternal vein serum: median 9.2 mg/L(6.0-12.3), p = .03 and umbilical vein serum: median 3.4 mg/L (2.1-5.6), p = .009.

CONCLUSION

The increased weight gain in pregnancy and concentration and proportions of DHA, n-3 PUFAs with a decreased proportion of AA, n-6 PUFAs, and AA/DHA ratio in maternal and umbilical vein serum summarize the effect of supplementation with EPA and DHA.

DHA Supplementation of Obese Rats throughout Pregnancy and Lactation Modifies Milk Composition and Anxiety Behavior of Offspring

We investigated if supplementing obese mothers (MO) with docosahexaenoic acid (DHA) improves milk long-chain polyunsaturated fatty acid (LCPUFA) composition and offspring anxiety behavior. From weaning throughout pregnancy and lactation, female Wistar rats ate chow (C) or a high-fat diet (MO). One month before mating and through lactation, half the mothers received 400 mg DHA kg⁻¹ d⁻¹ orally (C+DHA or MO+DHA). Offspring ate C after weaning. Maternal weight, total body fat, milk hormones, and milk nutrient composition were determined. Pups’ milk nutrient intake was evaluated, and behavioral anxiety tests were conducted. MO exhibited increased weight and total fat, and higher milk corticosterone, leptin, linoleic, and arachidonic acid (AA) concentrations, and less DHA content. MO male and female offspring had higher ω-6/ ω-3 milk consumption ratios. In the elevated plus maze, female but not male MO offspring exhibited more anxiety. MO+DHA mothers exhibited lower weight, total fat, milk leptin, and AA concentrations, and enhanced milk DHA. MO+DHA offspring had a lower ω-6/ω-3 milk intake ratio and reduced anxiety vs. MO. DHA content was greater in C+DHA milk vs. C. Supplementing MO mothers with DHA improves milk composition, especially LCPUFA content and ω-6/ω-3 ratio reducing offspring anxiety in a sex-dependent manner.

Maternal n-3 Polyunsaturated Fatty Acid Enriched Diet Commands Fatty Acid Composition in Postnatal Brain and Protects from Neonatal Arterial Focal Stroke

The fetus is strongly dependent on nutrients from the mother, including polyunsaturated fatty acids (PUFA). In adult animals, n-3 PUFA ameliorates stroke-mediated brain injury, but the modulatory effects of different PUFA content in maternal diet on focal arterial stroke in neonates are unknown. This study explored effects of maternal n-3 or n-6 enriched PUFA diets on neonatal stroke outcomes. Pregnant mice were assigned three isocaloric diets until offspring reached postnatal day (P) 10–13: standard, long-chain n-3 PUFA (n-3) or n-6 PUFA (n-6) enriched. Fatty acid profiles in plasma and brain of mothers and pups were determined by gas chromatography–mass spectrometry and cytokines/chemokines by multiplex protein analysis. Transient middle cerebral artery occlusion (tMCAO) was induced in P9-10 pups and cytokine and chemokine accumulation, caspase-3 and calpain-dependent spectrin cleavage and brain infarct volume were analyzed. The n-3 diet uniquely altered brain lipid profile in naïve pups. In contrast, cytokine and chemokine levels did not differ between n-3 and n-6 diet in naïve pups. tMCAO triggered accumulation of inflammatory cytokines and caspase-3-dependent and -independent cell death in ischemic-reperfused regions in pups regardless of diet, but magnitude of neuroinflammation and caspase-3 activation were attenuated in pups on n-3 diet, leading to protection against neonatal stroke. In conclusion, maternal/postnatal n-3 enriched diet markedly rearranges neonatal brain lipid composition and modulates the response to ischemia. While standard diet is sufficient to maintain low levels of inflammatory cytokines and chemokines under physiological conditions, n-3 PUFA enriched diet, but not standard diet, attenuates increases of inflammatory cytokines and chemokines in ischemic-reperfused regions and protects from neonatal stroke.

Anxiety-like behavior in female mice is modulated by STAT3 signaling in midbrain dopamine neurons

The central signaling actions of cytokines are mediated by signal transducer and activator of transcription (STAT3). STAT3 activation plays a pivotal role in the behavioral responses to the adiposity hormone leptin, including in midbrain dopamine (DA) neurons where it mediates the influence of leptin to diminish physical activity and running reward in male mice. Leptin also has anxiolytic effects which have been tied to the mesolimbic DA system. To assess the contribution of STAT3 signaling in mesolimbic DA neurons on feeding, mesolimbic DA tone and anxiodepressive behaviors in female mice, we generated DA-specific STAT3 knockout mice by crossing mice expressing Cre under the control of the dopamine transporter with STAT3-LoxP mice. Feeding, locomotion, wheel running, conditioned place preference for palatable food and amphetamine locomotor sensitization were unaffected by DA-specific STAT3 deletion. Conversely, knockout mice exhibited heightened anxiety-like behavior (open field test and elevated plus maze) along with increased basal and stress-induced plasma corticosterone, whereas indices of behavioral despair (forced swim and tail-suspension tasks) were unchanged. In accordance with biochemical evidence of increased D1 receptor signaling (phospho-DARPP32_Thr34) in the central nucleus of the amygdala (CeA) of knockout mice, local microinjections of a D1 receptor antagonist reversed the anxiogenic phenotype of knockout mice. In addition to alluding to sex differences in the signaling mechanisms mediating anxiety-like behavior, our findings suggest that activation of STAT3 in midbrain dopamine neurons projecting to the CeA dampens anxiety in a D1R-dependent manner in female mice.

Microglial Lipid Biology in the Hypothalamic Regulation of Metabolic Homeostasis

In mammals, myeloid cells help maintain the homeostasis of peripheral metabolic tissues, and their immunologic dysregulation contributes to the progression of obesity and associated metabolic disease. There is accumulating evidence that innate immune cells also serve as functional regulators within the mediobasal hypothalamus (MBH), a critical brain region controlling both energy and glucose homeostasis. Specifically, microglia, the resident parenchymal myeloid cells of the CNS, play important roles in brain physiology and pathology. Recent studies have revealed an expanding array of microglial functions beyond their established roles as immune sentinels, including roles in brain development, circuit refinement, and synaptic organization. We showed that microglia modulate MBH function by transmitting information resulting from excess nutrient consumption. For instance, microglia can sense the excessive consumption of saturated fats and instruct neurons within the MBH accordingly, leading to responsive alterations in energy balance. Interestingly, the recent emergence of high-resolution single-cell techniques has enabled specific microglial populations and phenotypes to be profiled in unprecedented detail. Such techniques have highlighted specific subsets of microglia notable for their capacity to regulate the expression of lipid metabolic genes, including lipoprotein lipase (LPL), apolipoprotein E (APOE) and Triggering Receptor Expressed on Myeloid Cells 2 (TREM2). The discovery of this transcriptional signature highlights microglial lipid metabolism as a determinant of brain health and disease pathogenesis, with intriguing implications for the treatment of brain disorders and potentially metabolic disease. Here we review our current understanding of how changes in microglial lipid metabolism could influence the hypothalamic control of systemic metabolism.

Weight gain and neuroadaptations elicited by high fat diet depend on fatty acid composition

Overconsumption of food is a major health concern in the western world. Palatable food has been shown to alter the activity of neural circuits, and obesity has been linked to alterations in the connectivity between the hypothalamus and cortical regions involved in decision-making and reward processing, putatively modulating the incentive value of food. Outlining neurophysiological adaptations induced by dietary intake of high fat diets (HFD) is thus valuable to establish how the diet by itself may promote overeating. To this end, C57BL/6 mice were fed HFD rich in either saturated fatty acids (HFD-S) or polyunsaturated fatty acids (HFD-P), or a low-fat control diet (LFD) for four weeks. Food and energy intake were monitored and ex vivo electrophysiology was employed to assess neuroadaptations in lateral hypothalamus (LH) and corticostriatal circuits, previously associated with food intake. In addition, the effects of dietary saturated and polyunsaturated fatty acids on the gene expression of NMDA, AMPA and GABA_A receptor subunits in the hypothalamus were investigated. Our data shows that mice fed HFD-P had increased daily food and energy intake compared with mice fed HFD-S or LFD. However, this increase in energy intake had no obesogenic effects. Electrophysiological recordings demonstrated that HFD-P had a selective effect on glutamatergic neurotransmission in the LH, which was concomitant with a change in mRNA expression of AMPA receptor subtypes Gria1, Gria3 and Gria4, with no effect on the mRNA expression of NMDA receptor subtypes or GABA_A receptor subtypes. Furthermore, while synaptic output from corticostriatal subregions was not significantly modulated by diet, synaptic plasticity in the form of long-term depression (LTD) was impaired in the dorsomedial striatum of mice fed HFD-S. In conclusion, this study suggests that the composition of fatty acids in the diet not only affects weight gain, but may also modulate neuronal function and plasticity in brain regions involved in food intake.

A Bidirectional View of Migraine and Diet Relationship

Migraine is a common headache with a large negative impact on health. Several endogenous and exogenous factors can influence the severity and frequency of migraine, for example, lifestyle factors including dietary factors. Consequently, lifestyle modifications and dietary considerations have been reported beneficial to moderate clinical features of migraine. Much effort has been invested in determining the lifestyle factors (eg, stress, exercise, sleep, and diet) that trigger migraine to develop recommendations and guidelines for prevention. Diet has also been investigated with a major focus on the content of the diet and to a lesser extent on the amount, pattern, and quality of diet. Identification of dietary factors in migraine has led to nutritional interventions with a major focus on elimination of triggers, and weight control strategies. Several so-called migraine diets have consequently been proposed, for example, the ketogenic diet. Some theories have considered epigenetic diets or functional food to help in altering components of migraine pathogenesis; however, these theories are less investigated. In contrast, evidence is being accumulated to support that some mechanisms underlying migraine may alter dietary choices, for example type, amount, or patterns. Since a causative relationship is not yet established in migraine-diet relationship as to which comes first, this concept is equally valuable and interesting to investigate. Only limited epidemiological data are available to demonstrate that dietary choices are different among patients with migraine compared with individuals without migraine. Differences are reflected on quality, composition, pattern, and the amount of consumption of dietary components. This view emphasizes a potential bidirectional relationship between migraine and diet rather than a one-way influence of one on the other. This targeted review presents examples from current literature on the effects of diet on migraine features and effects of migraine on dietary choices to draw a perspective for future studies.