Male mice engaging differently in emotional eating present distinct plasmatic and neurological profiles.

Objective: Stressed individuals tend to turn to calorie-rich food, also known as 'comfort food' for the temporary relief it provides. The emotional eating drive is highly variable among subjects. Using a rodent model, we explored the plasmatic and neurobiological differences between 'high and low emotional eaters' (HEE and LEE).Methods: 40 male mice were exposed for 5 weeks to a protocol of unpredictable chronic mild stress. Every 3 or 4 days, they were submitted to a 1-h restraint stress, immediately followed by a 3-h period during which a choice between chow and chocolate sweet cereals was proposed. The dietary intake was measured by weighing. Plasmatic and neurobiological characteristics were compared in mice displaying high vs low intakes.Results: Out of 40 mice, 8 were considered as HEE because of their high post-stress eating score, and 8 as LEE because of their consistent low intake. LEE displayed higher plasma corticosterone and lower levels of NPY than HEE, but acylated and total ghrelin were similar in both groups. In the brain, the abundance of NPY neurons in the arcuate nucleus of the hypothalamus was similar in both groups, but was higher in the ventral hippocampus and the basal lateral amygdala of LEE. The lateral hypothalamus LEE had also more orexin (OX) positive neurons. Both NPY and OX are orexigenic peptides and mood regulators.Discussion: Emotional eating difference was reflected in plasma and brain structures implicated in emotion and eating regulation. These results concur with the psychological side of food consumption.

Modulating adult neurogenesis through dietary interventions.

Three areas in the brain continuously generate new neurons throughout life: the subventricular zone lining the lateral ventricles, the dentate gyrus in the hippocampus and the median eminence in the hypothalamus. These areas harbour neural stem cells, which contribute to neural repair by generating daughter cells that then become functional neurons or glia. Impaired neurogenesis leads to detrimental consequences, such as depression, decline of cognitive abilities and obesity. Adult neurogenesis is a versatile process that can be modulated either positively or negatively by many effectors, external or endogenous. Diet can modify neurogenesis both ways, either directly by ways of food-borne molecules, or possibly by the modifications induced on gut microbiota composition. It is therefore critical to define dietary strategies optimal for the maintenance of the stem cell pools.

Omega-3 polyunsaturated fatty acids and brain aging.

PURPOSE OF REVIEW: The literature on the influence of dietary omega-3 polyunsaturated fatty acid (ω-3 PUFA) on brain aging has grown exponentially during the last decade. Many avenues have been explored but no global picture or clear evidence has emerged. Experimental studies have shown that ω-3 PUFA is involved in many neurobiological processes that are involved in neurotransmission and neuroprotection, indicating that these PUFAs may prevent age-related brain damage. Human studies have revealed only a weak link between ω-3 PUFA status and cognitive aging, whereas interventional studies have yet to confirm it. The purpose of this review is to analyze the developments in the area during the last 2 years. RECENT FINDINGS: Human brain MRI studies have confirmed previous findings that ω-3 PUFA can protect the brain during aging; two intervention studies obtained clear evidence. We also analyzed the experimental data clarifying the involvement of ω-3 PUFA in neurotransmission, neuroprotection (including prevention of peroxidation, inflammation, and excitotoxicity), and neurogenesis, thereby helping the brain cope with aging. SUMMARY: These recent human and experimental studies provide support for and clarification of how ω-3 PUFA protect against brain aging and highlight the main lines for future research.

Glucose but Not Fructose Alters the Intestinal Paracellular Permeability in Association With Gut Inflammation and Dysbiosis in Mice.

A causal correlation between the metabolic disorders associated with sugar intake and disruption of the gastrointestinal (GI) homeostasis has been suggested, but the underlying mechanisms remain unclear. To unravel these mechanisms, we investigated the effect of physiological amounts of fructose and glucose on barrier functions and inflammatory status in various regions of the GI tract and on the cecal microbiota composition. C57BL/6 mice were fed chow diet and given 15% glucose or 15% fructose in drinking water for 9 weeks. We monitored caloric intake, body weight, glucose intolerance, and adiposity. The intestinal paracellular permeability, cytokine, and tight junction protein expression were assessed in the jejunum, cecum, and colon. In the cecum, the microbiota composition was determined. Glucose-fed mice developed a marked increase in total adiposity, glucose intolerance, and paracellular permeability in the jejunum and cecum while fructose absorption did not affect any of these parameters. Fructose-fed mice displayed increased circulation levels of IL6. In the cecum, both glucose and fructose intake were associated with an increase in Il13, Ifnγ, and Tnfα mRNA and MLCK protein levels. To clarify the relationships between monosaccharides and barrier function, we measured the permeability of Caco-2 cell monolayers in response to IFNγ+TNFα in the presence of glucose or fructose. In vitro, IFNγ+TNFα-induced intestinal permeability increase was less pronounced in response to fructose than glucose. Mice treated with glucose showed an enrichment of Lachnospiracae and Desulfovibrionaceae while the fructose increased relative abundance of Lactobacillaceae. Correlations between pro-inflammatory cytokine gene expression and bacterial abundance highlighted the potential role of members of Desulfovibrio and Lachnospiraceae NK4A136 group genera in the inflammation observed in response to glucose intake. The increase in intestinal inflammation and circulating levels of IL6 in response to fructose was observed in the absence of intestinal permeability modification, suggesting that the intestinal permeability alteration does not precede the onset of metabolic outcome (low-grade inflammation, hyperglycemia) associated with chronic fructose consumption. The data also highlight the deleterious effects of glucose on gut barrier function along the GI tract and suggest that Desulfovibrionaceae and Lachnospiraceae play a key role in the onset of GI inflammation in response to glucose.

Maternal Microbiota Transfer Programs Offspring Eating Behavior.

Understanding the link between mother's obesity and regulation of the child's appetite is a prerequisite for the design of successful preventive strategies. Beyond the possible contributions of genetic heritage, family culture, and hormonal and metabolic environment during pregnancy, we investigate in the present paper the causal role of the transmission of the maternal microbiotas in obesity as microbiotas differ between lean and obese mothers, maternal microbiotas are the main determinants of a baby's gut colonization, and the intestinal microbiota resulting from the early colonization could impact the feeding behavior of the offspring with short- and long-term consequences on body weight. We thus investigated the potential role of vertical transfers of maternal microbiotas in programming the eating behavior of the offspring. Selectively bred obese-prone (OP)/obese-resistant (OR) Sprague-Dawley dams were used since differences in the cecal microbiota have been evidenced from males of that strain. Microbiota collected from vagina (at the end of gestation), feces, and milk (at postnatal days 1, 5, 10, and 15) of OP/OR dams were orally inoculated to conventional Fischer F344 recipient pups from birth to 15 days of age to create three groups of pups: F-OP, F-OR, and F-Sham group (that received the vehicle). We first checked microbiotal differences between inoculas. We then assessed the impact of transfer (from birth to adulthood) onto the intestinal microbiota of recipients rats, their growth, and their eating behavior by measuring their caloric intake, their anticipatory food reward responses, their preference for sweet and fat tastes in solutions, and the sensations that extend after food ingestion. Finally, we searched for correlation between microbiota composition and food intake parameters. We found that maternal transfer of microbiota differing in composition led to alterations in pups' gut microbiota composition that did not last until adulthood but were associated with specific eating behavior characteristics that were predisposing F-OP rats to higher risk of over consuming at subsequent periods of their life. These findings support the view that neonatal gut microbiotal transfer can program eating behavior, even without a significant long-lasting impact on adulthood microbiota composition.

Long chain-polyunsaturated fatty acids modulate membrane phospholipid composition and protein localization in lipid rafts of neural stem cell cultures.

Rat neural stem cells/neural progenitors (NSC/NP) are generally grown in serum-free medium. In this study, NSC/NP were supplemented with the main long-chain polyunsaturated fatty acids (PUFAs) present in the brain, arachidonic acid (AA), or docosahexaenoic acid (DHA), and were monitored for their growth. Lipid and fatty acid contents of the cells were also determined. Under standard conditions, the cells were characterized by phospholipids displaying a highly saturated profile, and very low levels of PUFAs. When cultured in the presence of PUFAs, the cells easily incorporated them into the phospholipid fraction. We also compared the presence of three membrane proteins in the lipid raft fractions: GFR and connexin 43 contents in the rafts were increased by DHA supplementation, whereas Gbeta subunit content was not significantly modified. The restoration of DHA levels in the phospholipids could profoundly affect protein localization and, consequently, their functionalities.

Estradiol favors the formation of eicosapentaenoic acid (20:5n-3) and n-3 docosapentaenoic acid (22:5n-3) from alpha-linolenic acid (18:3n-3) in SH-SY5Y neuroblastoma cells.

Whether neurosteroids regulate the synthesis of long chain polyunsaturated fatty acids in brain cells is unknown. We examined the influence of 17-beta-estradiol (E2) on the capacity of SH-SY5Y cells supplemented with alpha-linolenic acid (ALA), to produce eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA). Cells were incubated for 24 or 72 h with ALA added alone or in combination with E2 (ALA + E2). Fatty acids were analyzed by gas chromatography of ethanolamine glycerophospholipids (EtnGpl) and phosphatidylcholine (PtdCho). Incubation for 24 h with ALA alone increased EPA and DPA in EtnGpl, by 330 and 430% compared to controls (P < 0.001) and DHA by only 10% (P < 0.05). Although DHA increased by 30% (P < 0.001) in ALA + E2-treated cells, the difference between the ALA and ALA + E2 treatments were not significant after 24 h (Anova-1, Fisher's test). After 72 h, EPA, DPA and DHA further increased in EtnGpl and PtdCho of cells supplemented with ALA or ALA + E2. Incubation for 72 h with ALA + E2 specifically increased EPA (+34% in EtnGpl, P < 0.001) and DPA (+15%, P < 0.001) compared to ALA alone. Thus, SH-SY5Y cells produced membrane EPA, DPA and DHA from supplemental ALA. The formation of DHA was limited, even in the presence of E2. E2 significantly favored EPA and DPA production in cells grown for 72 h. Enhanced synthesis of ALA-elongation products in neuroblastoma cells treated with E2 supports the hypothesis that neurosteroids could modulate the metabolism of PUFA.

Sex steroids and neurogenesis.

The brain has long been known as a dimorphic organ and as a target of sex steroids. It is also a site for their synthesis. Sex steroids in numerous ways can modify cerebral physiology, and along with many processes adult neurogenesis is also modulated by sex steroids. This review will focus on the effects of the main steroids, estrogens, androgens and progestogens, and unveil some aspects of their partly disclosed mechanisms of actions. Gonadal steroids act on different steps of neurogenesis: cell proliferation seems to be increased by estrogens only, while androgens and progestogens favor neuronal renewal by increasing cell survival; differentiation is a common target. Aging is characterized by a cognitive deficiency, paralleled by a decrease in the rate of neuronal renewal and in the levels of circulating gonadal hormones. Therefore, the effects of gonadal hormones on the aging brain are important to consider. The review will also be expanded to related molecules which are agonists to the nuclear receptors. Sex steroids can modify adult neuronal renewal and the extensive knowledge of their actions on neurogenesis is essential, as it can be a leading pathway to therapeutic perspectives.

Detection of a raft-located estrogen receptor-like protein distinct from ER alpha.

17Beta-estradiol (17beta-E2) elicits at the cell membrane rapid actions that remain insensitive to the inhibitory effect of ICI 182,780, a pure estrogen antagonist, and therefore cannot be attributed to the classic nuclear receptors. We addressed the question of the identity of the protein involved in these rapid actions. We first examined the responses of several cell lines for intracellular calcium mobilization, an effect not inhibited by ICI 182,780, tamoxifen and raloxifen. We then demonstrated the presence of binding sites in the membranes, by incubating them with antibodies directed against different domains of ER alpha, and by flow cytometry analysis. The membrane proteins were eluted by affinity chromatography using E2 conjugated to bovine serum albumin as a ligand. Western blots of the elution fractions using an antibody directed against the ligand binding site of ER alpha showed the existence of a protein of approximately 50 kDa. The protein was concentrated in the lipid rafts, together with another heavier form of approximately 66 kDa. The 50 kDa protein was immunoprecipitable, and co-immunoprecipitation experiments showed that it was associated with the Gbeta(1-4) protein, but not with caveolin-1. The protein was expressed in ER alpha-null cells, like HO-23 and Cos-7 cells. Therefore, in the lipid rafts, there exists a protein, similar to, but molecularly distinct from ER alpha.

Fatty acid binding protein 7 and n-3 poly unsaturated fatty acid supply in early rat brain development.

Fatty acid binding protein 7 (FABP7), abundant in the embryonic brain, binds with the highest affinity to docosahexaenoic acid (DHA) and is expressed in the early stages of embryogenesis. Here, we have examined the consequences of the exposure to different DHA levels and of the in utero depletion of FABP7 on early rat brain development. Neurodevelopment was evaluated through the contents of two proteins, connexin 43 (Cx43) and cyclin-dependent kinase 5 (CDK5), both involved in neuroblast proliferation, differentiation, and migration. The dams were fed with diets presenting different DHA contents, from deficiency to supplementation. DHA brain embryos contents already differed at embryonic day 11.5 and the differences kept increasing with time. Cx43 and CDK5 contents were positively associated with the brain DHA levels. When FABP7 was depleted in vivo by injections of siRNA in the telencephalon, the enhancement of the contents of both proteins was lost in supplemented animals, but FABP7 depletion did not modify phospholipid compositions regardless of the diets. Thus, FABP7 is a necessary mediator of the effect of DHA on these proteins synthesis, but its role in DHA uptake is not critical, although FABP7 is localized in phospholipid-rich areas. Our study shows that high contents of DHA associated with FABP7 are necessary to promote early brain development, which prompted us to recommend DHA supplementation early in pregnancy.

Role of Mtd/Bok in normal and neoplastic B-cell development in the bursa of Fabricius.

B-cell development in the bursa of Fabricius is accompanied by extensive apoptotic cell death. Apoptosis, however, is suppressed during c-myc-induced neoplasia. The experiments described here suggest that Mtd/Bok may drive apoptosis during normal development, and that this activity is blocked during myc-induced tumorigenesis. Bursal Mtd/Bok expression increases during development, correlating with the onset of intense, spontaneous apoptosis after hatching. Two isoforms of Mtd/Bok were characterized: WT-chMtd/Bok, found predominantly in the mitochondria and a less abundant form, lacking the presumptive transmembrane domain, Mtd/Bok deltaTM, found predominantly in the cytosol. Over-expression of Mtd/Bok deltaTM in a bursal lymphoma-derived cell line, DT40, reduced mitochondrial function and sensitized DT40 cells to apoptotic stimuli, while WT-chMtd/Bok had a diminished phenotype in these cells. In contrast, retroviral transduction of bursal stem cells with WT-chMtd/Bok ablated normal stem cell function in transplantation experiments, and produced extensive apoptosis in myc-induced pre-neoplastic bursal populations, but not in tumor cells.

Rat neural stem cell proliferation and differentiation are durably altered by the in utero polyunsaturated fatty acid supply.

We isolated neural stem cells/neural progenitors (NSC) from 1-day-old rat pups born to mothers fed diets that were deficient or supplemented with n-3 polyunsaturated fatty acids (PUFAs) and compared their proliferation and differentiation in vitro. The cells isolated from the n-3PUFA-deficient pups consistently proliferated more slowly than cells that were isolated from n-3PUFA-supplemented pups, despite the fact that both were cultured under the same conditions. The differences in the proliferation rates were evaluated up until 40 days of culture and were highly significant. When the cells were allowed to differentiate, the deficient cells exhibited a higher degree of neuronal maturation in response to the addition of PUFAs in the medium, as demonstrated by an increase in neurite length, whereas the neurons derived from the supplemented pups showed no change. This result was consistent, regardless of the age of the culture. The properties of the NSC were durably modified throughout the length of the culture, although the membrane phospholipid compositions were similar. We examined the differential expression of selected mRNAs and micro RNAs. We found significant differences in the gene expression of proliferating and differentiating cells, and a group of genes involved in neurogenesis was specifically modified by n-3 PUFA treatment. We conclude that n-3 PUFA levels in the maternal diet can induce persistent modifications of the proliferation and differentiation of NSCs and of their transcriptome. Therefore, the n-3 supply received in utero may condition on a long-term basis cell renewal in the brain.

Dexamethasone inhibits the maturation of newly formed neurons and glia supplemented with polyunsaturated fatty acids.

Stress bears a negative impact on adult neurogenesis. High levels of corticoids have been shown to inhibit neural stem cell proliferation, and are considered responsible for the loss of neural precursors. Their effects on the differentiation of the glial and neuronal lineages have been less studied. We examined the effect of dexamethasone (Dex), a synthetic glucocorticoid, on the differentiation of rat neural stem cells in vitro. Dex had no effect on the differentiation of cells cultured under standard conditions. Since we previously determined that NSC, when cultured under classical conditions, were deprived of polyunsaturated fatty acids (PUFA), and displayed phospholipid compositions very different from the in vivo figures [1], we examined the effect of Dex under PUFA supplementation. Dex impaired neuron and oligodendrocyte maturation in PUFA-supplemented cells, demonstrated by the reduction of neurite lengths and oligodendrocyte sizes. This effect was mediated by the glucocorticoid receptor (GR), since it was eliminated by mifepristone, a GR antagonist, and could be relayed by a reduction of ERK phosphorylation. We determined that GR was associated with PPAR ß and α under basal conditions, and that this association was disrupted when PUFA were added in combination with Dex. We assumed that this effect on the receptor status enabled the effect of Dex on PUFA supplemented cells, since we determined that the binding to the glucocorticoid response element was higher in cells incubated with PUFA and Dex. In conclusion, corticoids can impair NSC differentiation, and consequently impact the entire process of neurogenesis.

Signaling networks from Gbeta1 subunit to transcription factors and actin remodeling via a membrane-located ERbeta-related protein in the rapid action of daidzein in osteoblasts.

Although estrogen replacement has been the main therapy to prevent and treat osteoporosis, there are concerns about its safety. Phytoestrogens have attracted attention to their potential impacts in osteoporosis prevention and treatment. Among phytoestrogens, the isoflavone daidzein (Dz) acts on transcription via the intracellular estrogen receptors (ER), mainly ERbeta, in osteoblasts, but mimics only part of the estrogen effects. Since estradiol also exerts rapid effects in osteoblasts, we investigated the multistep processes involved in the rapid actions of low (1-100 pM) doses of daidzein. Dz bound to a membrane moiety, related to ERbeta since the calcium response to Dz was blocked by an anti-ERbeta antibody directed against the C-terminus, but not by a double-stranded siRNA specific for ERbeta. This protein was coupled to a pertussis toxin (PTX)-sensitive Gbeta1 subunit whose transducer was PLC-beta2, which triggered a rapid (5 sec) mobilization of calcium from the endoplasmic reticulum. Dz phosphorylated within 15 sec ERK1/2 whose phosphorylation involved two routes: Gbeta1/PLC-beta2/PKC/c-Raf-1/MEK1/2 and Gbeta1/PI3K/cSrc/c-Raf-1/MEK1/2 as shown using several inhibitors. Dz induced rapid (1 min) changes in the actin cytoskeleton via the two routes. The rapid (20 sec) phosphorylation of Elk-1 and CREB by Dz involved Gbeta1 and ERK1/2. All the processes were insensitive to the estradiol antagonist ICI 182,780. In conclusion, the rapid effects of Dz seem to be biologically relevant for the function of osteoblast in bone since the isoflavone activates transcription factors linked to early genes controlling cellular proliferation and differentiation, and modulates actin cytoskeleton which controls cell adhesion, division, or secretion.