Maternal high-fat diet stimulates proinflammatory pathway and increases the expression of Tryptophan Hydroxylase 2 (TPH2) and brain-derived neurotrophic factor (BDNF) in adolescent mice hippocampus.

Maternal high-fat diet (HFD) consumption can promote a systemic inflammatory condition that may impair the offspring brain development, damaging memory and learning, when it reaches the hippocampus. This study aims to evaluate maternal HFD effects, during pregnancy and lactation, upon dams/mice offspring nutritional status, protein and gene expression of inflammatory pathway (JNK, pJNK and TNF-α), serotonin system molecules (Tryptophan Hydroxylase 2 (TPH2), key-enzyme of serotonin synthesis, serotonin transporter (SERT); 5-HT1A serotonergic receptor (5-HT1A)) and brain derived neurotrophic factor (BDNF) on recently weaned mice offspring hippocampus. Female Swiss mice were fed a control diet (CD, 11,5% fat) or a HFD (45.0% fat) from pre-mating to lactation. After weaning, the offspring received CD up to 28 post-natal days (PND28). Body weight and visceral adiposity (retroperitoneal and gonadal adipose tissue) of dams and offspring were measured. After euthanasia, the offspring hippocampus was dissected for evaluations of BDNF, inflammatory pathway and serotonergic system molecules protein and gene expression, through the techniques of Western Blotting, RTqPCR and ELISA. Our findings show that, during pregnancy, HFD-dams and HFD-offspring exhibited an increase in body weight gain and visceral adipose tissue compared to control animals. The hippocampus of HFD-offspring showed increased protein expression of TPH2, BDNF, pJNK and increased mRNA levels of TNF-α. However, the TPH2 increase in HFD-offspring did not alter hippocampal serotonin levels quantified through ELISA. Maternal HFD promoted an obesity phenotype in its offspring with increased body weight and visceral adiposity, increased protein and gene expression of the pro-inflammatory proteins pJNK and TNF-α. These changes were accompanied by increased TPH2 and BDNF protein expression. Thus, our findings show that maternal HFD during gestation and lactation increased pJNK and TNF-α expression in their offspring hippocampus indicating a pro-inflammatory state, with increased BDNF expression and alterations in its serotonergic system reflected by increased TPH2 expression.

Modulation of hypothalamic S6K1 and S6K2 alters feeding behavior and systemic glucose metabolism.

The mTOR/S6Ks signaling is one of the intracellular pathways important for metabolic control, acting both peripherally and centrally. In the hypothalamus, mTOR/S6Ks axis mediates the action of leptin and insulin and can modulate the expression of neuropeptides. We analyzed the role of different S6Ks isoforms in the hypothalamic regulation of metabolism. We observed decreased food intake and decreased expression of agouti-related peptide (AgRP) following intracerebroventricular (icv) injections of adenoviral-mediated overexpression of three different S6Ks isoforms. Moreover, mice overexpressing p70-S6K1 in undefined periventricular hypothalamic neurons presented changes in glucose metabolism, as an increase in gluconeogenesis. To further evaluate the hypothalamic role of a less-studied S6K isoform, p54-S6K2, we used a Cre-LoxP approach to specifically overexpress it in AgRP neurons. Our findings demonstrate the potential participation of S6K2 in AgRP neurons regulating feeding behavior.

Short-Term High-Fat Diet Consumption Reduces Hypothalamic Expression of the Nicotinic Acetylcholine Receptor α7 Subunit (α7nAChR) and Affects the Anti-inflammatory Response in a Mouse Model of Sepsis.

Sepsis is one of the leading causes of death in hospitalized patients and the chronic and low-grade inflammation observed in obesity seems to worsen susceptibility and morbidity of infections. However, little is known with respect to a short-term high-fat diet (HFD) and its role in the development of sepsis. Here, we show for the first time, that short-term HFD consumption impairs early nicotinic acetylcholine receptor α7 subunit (α7nAChR)- mediated signaling, one of the major components of the cholinergic anti-inflammatory pathway, with a focus on hypothalamic inflammation and innate immune response. Mice were randomized to a HFD or standard chow (SC) for 3 days, and sepsis was subsequently induced by a lethal intraperitoneal (i.p.) injection of lipopolysaccharide (LPS) or by cecal ligation and puncture (CLP) surgery. In a separate experiment, both groups received LPS (i.p.) or LPS (i.p.) in conjunction with the selective α7nAChR agonist, PNU-282987 (i.p. or intracerebroventricular; i.c.v.), and were sacrificed 2 h after the challenge. Short-term HFD consumption significantly reduced the α7nAChR mRNA and protein levels in the hypothalamus and liver (p < 0.05). Immunofluorescence microscopy demonstrated lower cholinergic receptor nicotinic α7 subunit (α7nAChR)+ cells in the arcuate nucleus (ARC) (α7nAChR+ cells in SC = 216 and HFD = 84) and increased F4/80+ cells in the ARC (2.6-fold) and median eminence (ME) (1.6-fold), which can contribute to neuronal damage. Glial fibrillary acidic protein (GFAP)+ cells and neuronal nuclear antigen (NeuN)+ cells were also increased following consumption of HFD. The HFD-fed mice died quickly after a lethal dose of LPS or following CLP surgery (2-fold compared with SC). The LPS challenge raised most cytokine levels in both groups; however, higher levels of TNF-α (Spleen and liver), IL-1ß and IL-6 (in all tissues evaluated) were observed in HFD-fed mice. Moreover, PNU-282987 administration (i.p. or i.c.v.) reduced the levels of inflammatory markers in the hypothalamus following LPS injection. Nevertheless, when the i.c.v. injection of PNU-282987 was performed the anti-inflammatory effect was much smaller in HFD-fed mice than SC-fed mice. Here, we provide evidence that a short-term HFD impairs early α7nAChR expression in central and peripheral tissues, contributing to a higher probability of death in sepsis.

Protein restriction in early life increases intracellular calcium and insulin secretion, but does not alter expression of SNARE proteins during pregnancy.

NEW FINDINGS: What is the central question of this study? Does protein restriction in early life modify glucose-induced insulin secretion by altering [Ca2+ ]i and the expression of SNARE proteins in pancreatic islets from pregnant rats? What is the main finding and its importance? Protein restriction in early life increased the first phase of glucose-induced insulin secretion and [Ca2+ ]i without altering the expression of SNARE proteins during pregnancy. This finding contributes to our understanding of the mechanisms of altered insulin secretion and might provide new perspectives for the development of therapeutic tools for gestational diabetes. ABSTRACT: We investigated the kinetics of glucose-induced insulin secretion and their relationship with [Ca2+ ]i and the expression of protein from exocytotic machinery in islets from recovered pregnant and long-term protein-deficient pregnant rats. Isolated islets were evaluated from control-fed pregnant (CP), protein-deficient pregnant (DP), control-fed non-pregnant (CNP) and protein-deficient non-pregnant (DNP) female adult rats, and from protein-deficient pregnant (RP) and non-pregnant (RNP) rats that were recovered after weaning. The insulin responses to glucose during the first phase of secretion were higher in RP than in CP groups, and both were higher than in the DP group. Islets from RP rats displayed a rapid increase in insulin release (first phase), followed by a plateau that was maintained thereafter. The [Ca2+ ]i in islets from the protein-deficient groups was lower than in the control groups, and both were lower than in the RP and RNP groups. SNAP-25 was increased in islets from pregnant rats independently of their nutritional status, and the syntaxin-1A content was reduced in islets from the RP rats compared with the RNP rats. The VAMP2 content was similar among the groups. Thus, protein restriction during intrauterine life and lactation increased insulin secretion during pregnancy, attributable, in part, to increased [Ca2+ ]i , and independent of an alteration of expression of SNARE proteins.

Maternal Consumption of High-fat Diet in Mice Alters Hypothalamic Notch Pathway, NPY Cell Population and Food Intake in Offspring.

Studies show that maternal consumption of a high-fat diet (HFD) can impair the formation of hypothalamic neuronal circuits in mouse offspring. This damage can be mediated by Notch1/Hes5 signaling activation, leading to repression of proneural factors such as Mash1 and Ngn2/3, which are essential for neuronal differentiation and neurogenesis. Thus, we aimed to investigate the effects of maternal HFD consumption during gestation and lactation on the Notch1/Mash1 pathway in the hypothalamus and arcuate nucleus (ARC) of mouse offspring (neonates and 28 days old). Our results showed that maternal HFD consumption increases body weight and adiposity of mouse offspring, accompanied by increased levels of Il-1ß mRNA compared to those in control offspring. We noticed high mRNA levels of Hes5 accompanied by diminished mRNA levels of Ascl1 (Mash1). The number of Mash1-labeled cells in the ARC was diminished in HFD-O. Additionally, the population of NPY neurons was increased in these animals. Mash1 is important for the development of POMC and NPY neurons in the ARC. Therefore, the reduction in Mash1-labeled cells could be related to modification of the NPY neuron population in the ARC. This scenario favors hyperphagia and weight gain, and could be responsible for the development of obesity in adulthood.

High-fat diet during pregnancy and lactation impairs the cholinergic anti-inflammatory pathway in the liver and white adipose tissue of mouse offspring.

Cholinergic anti-inflammatory pathway (CAP) prevents inflammatory cytokines production. The main was to evaluate the effect of maternal obesity on cholinergic pathway in the offspring. Female mice were subjected to either standard chow (SC) or high-fat diet (HFD) during pregnancy and the lactation period. After weaning, only male offspring from HFD dams (HFD-O) and from SC dams (SC-O) were fed the SC diet. Key proteins of the CAP were downregulated and serum TNF-α was elevated in the HFD-O mice. STAT3 and NF-κB activation in HFD-O mice ICV injected with nicotine (agonist) were lower than SC-O mice. Basal cholinesterase activity was upregulated in HFD-O mice in both investigated tissues. Lipopolysaccharide increased TNF-α and IL-1ß expression in the liver and WAT of SC-O mice, but this effect was greater in HFD-O mice. In conclusion these changes exacerbated cytokine production in response to LPS and contributed to the reduced sensitivity of the CAP.

Increased expression of Hes5 protein in Notch signaling pathway in the hippocampus of mice offspring of dams fed a high-fat diet during pregnancy and suckling.

Maternal high-fat diet (HFD) impairs hippocampal development of offspring promoting decreased proliferation of neural progenitors, in neuronal differentiation, in dendritic spine density and synaptic plasticity reducing neurogenic capacity. Notch signaling pathway participates in molecular mechanisms of the neurogenesis. The activation of Notch signaling leads to the upregulation of Hes5, which inhibits the proliferation and differentiation of neural progenitors. This study aimed to investigate the Notch/Hes pathway activation in the hippocampus of the offspring of dams fed an HFD. Female Swiss mice were fed a control diet (CD) and an HFD from pre-mating until suckling. The bodyweight and mass of adipose tissue in the mothers and pups were also measured. The mRNA and protein expression of Notch1, Hes5, Mash1, and Delta1 in the hippocampus was assessed by RT-PCR and western blotting, respectively. Dams fed the HFD and their pups had an increased bodyweight and amount of adipose tissue. Furthermore, the offspring of mothers fed the HFD exhibited an increased Hes5 expression in the hippocampus compared with CD offspring. In addition, HFD offspring also expressed increased amounts of Notch1 and Hes5 mRNA, whereas Mash1 expression was decreased. However, the expression of Delta1 did not change significantly. We propose that the overexpression of Hes5, a Notch effector, downregulates the expression of the proneural gene Mash1 in the offspring of obese mothers, delaying cellular differentiation. These results provide further evidence that an offspring's hippocampus is molecularly susceptible to maternal HFD and suggest that Notch1 signaling in this brain region is important for neuronal differentiation.

Nutritional recovery with okara diet prevented hypercholesterolemia, hepatic steatosis and glucose intolerance.

We assessed the biological value of an okara diet and its effects on the hormonal and metabolic profile of rats submitted to protein restriction during intra-uterine life and lactation and recovered after weaning. Male rats from mothers fed either 17% or 6% protein during pregnancy and lactation were maintained on 17% casein (CC, LC), 17% okara (CO, LO) or 6% casein (LL) diets over 60 d. The nutritional quality of the okara protein was similar to that of casein. The okara diet was effective in the nutritional recovery of rats in growing that were malnourished in early life. Furthermore, the okara diet reversed the hypercholesterolemia and the hepatic steatosis observed in the malnutrition and prevented glucose intolerance in an animal model prone to diabetes mellitus.