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Background: Malnutrition is a global problem that affects schoolchildren and can increase the risk of diseases in adulthood. Adult members of the Yaqui Indigenous group have been shown to have serious health problems, and Yaqui schoolchildren could therefore find themselves in a similar situation., Objective: To evaluate the nutritional status, lipid profile and associated factors in a sample of Yaqui schoolchildren., Material and Methods: A total of 109 Yaqui schoolchildren who lived in their localities of origin were recruited. Anthropometric measurements were carried out, a venous blood sample was extracted in fasting conditions, and several questionnaires were applied., Results: The prevalence of overweight/obesity was 38.5%, with no cases of chronic malnutrition being recorded; 38.6% of the children had dyslipidemia. Fiber consumption was a protective factor against overweight/obesity, while fat intake was a risk factor. The physical activity score was found to be a protective factor against dyslipidemia, and the risk factors were BMI-for-age Z-scores, waist circumference, family history of dyslipidemia, educational level, and permanent employment., Conclusions: Yaqui schoolchildren equally suffer from a high proportion of overweight/obesity and dyslipidemia. The associated factors may be useful for the design of contextualized interventions for this population., (Copyright: © 2024 Permanyer.)

Background: Avoidant restrictive food intake disorder (ARFID) is a new eating disorder with a heterogeneous clinical presentation. It is unclear which patient characteristics contribute to its heterogeneity., Methods: To identify these patient characteristics, we performed symptom-level correlation and driver-level regression analyses in our cross-sectional study in up to 261 ARFID patients (51% female; median age = 12.7 years) who were assessed at the Maudsley Centre for Child and Adolescent Eating Disorders, London between November 2019 and July 2022., Findings: Symptoms across the three drivers 1) avoidance based on sensory characteristics of food; 2) apparent lack of interest in eating; and 3) concern about aversive consequences positively correlated with each other. Patients' anxiety traits showed the greatest positive correlations with symptoms of concern about aversive consequences of eating. Patient sex was not significantly associated with any of the three ARFID drivers. Patients with comorbid autism spectrum disorder (ASD; 28%) showed more food-related sensory sensitivities (RR = 1.26) and greater lack of interest in eating (RR = 1.18) than those of patients without ASD (49%)., Interpretation: In our clinical sample, the ARFID drivers occurred together and did not show clinically meaningful differences between the sexes. ASD may accentuate food-related sensory sensitivities and lack of interest, but may not drive a completely different symptom presentation. ARFID is multi-faceted and heterogenous, requiring a comprehensive multidisciplinary assessment to sufficiently understand the drivers of the restrictive eating behaviour. Results need replication in larger samples with more statistical power., Funding: None., Competing Interests: All authors have no disclosures., (© 2023 The Author(s).)

Over the last decade, the zebrafish has emerged as an important model organism for behavioural studies and neurological disorders, as well as for the study of metabolic diseases. This makes zebrafish an alternative model for studying the effects of energy disruption and nutritional quality on a wide range of behavioural aspects. Here, we used the zebrafish model to study how obesity induced by overfeeding regulates emotional and cognitive processes. Two groups of fish (n = 24 per group) were fed at 2% (CTRL) and 8% (overfeeding-induced obesity, OIO) for 8 weeks and tested for anxiety-like behaviour using the novel tank diving test (NTDT). Fish were first tested using a short-term memory test (STM) and then trained for four days for a long-term memory test (LTM). At the end of the experiment, fish were euthanised for biometric sampling, total lipid content, and triglyceride analysis. In addition, brains (eight per treatment) were dissected for HPLC determination of monoamines. Overfeeding induced faster growth and obesity, as indicated by increased total lipid content. OIO had no effect on anxiety-like behaviour. Animals were then tested for cognitive function (learning and memory) using the aversive learning test in Zantiks AD units. Results show that both OIO and CTRL animals were able to associate the aversive stimulus with the conditioned stimulus (conditioned learning), but OIO impaired STM regardless of fish sex, revealing the effects of obesity on cognitive processes in zebrafish. Obese fish did not show a deficiency in monoaminergic transmission, as revealed by quantification of total brain levels of dopamine and serotonin and their metabolites. This provides a reliable protocol for assessing the effect of metabolic disease on cognitive and behavioural function, supporting zebrafish as a model for behavioural and cognitive neuroscience.

Feeding motivation plays a crucial role in food intake and growth. It closely depends on hunger and satiation, which are controlled by the melanocortin system. Overexpression of the inverse agonist agouti-signalling protein (ASIP) and agouti-related protein (AGRP) leads to enhanced food intake, linear growth, and weight. In zebrafish, overexpression of Agrp leads to the development of obesity, in contrast to the phenotype observed in transgenic zebrafish that overexpress asip1 under the control of a constitutive promoter ( asip1-Tg ). Previous studies have demonstrated that asip1-Tg zebrafish exhibit larger sizes but do not become obese. These fish display increased feeding motivation, resulting in a higher feeding rate, yet a higher food ration is not essential in order to grow larger than wild-type (WT) fish. This is most likely attributed to their improved intestinal permeability to amino acids and enhanced locomotor activity. A relationship between high feeding motivation and aggression has been previously reported in some other transgenic species showing enhanced growth. This study aims to elucidate whether the hunger observed in asip1-Tg is linked to aggressive behaviour. Dominance and aggressiveness were quantified using dyadic fights and mirror-stimulus tests, in addition to the analysis of basal cortisol levels. The results indicate that asip1-Tg are less aggressive than WT zebrafish in both dyadic fights and mirror-stimulus tests.

In teleost, as in other vertebrates, stress affects reproduction. A key component of the stress response is the pituitary secretion of the adrenocorticotropic hormone (ACTH), which binds to the melanocortin 2 receptor (MC2R) in the adrenal glands and activates cortisol biosynthesis. In zebrafish, Mc2r was identified in male and female gonads, while ACTH has been shown to have a physiological role in modulating reproductive activity. In this study, the hypothesis that other melanocortins may also affect how the zebrafish gonadal function is explored, specifically steroid biosynthesis, given the presence of members of the melanocortin signaling system in zebrafish gonads. Using cell culture, expression analysis, and cellular localization of gene expression, our new observations demonstrated that melanocortin receptors, accessory proteins, antagonists, and agonists are expressed in both the ovary and testis of zebrafish ( n = 4 each sex). Moreover, melanocortin peptides modulate both basal and gonadotropin-stimulated steroid release from zebrafish gonads ( n = 15 for males and n = 50 for females). In situ hybridization in ovaries ( n = 3) of zebrafish showed mc1r and mc4r in follicular cells and adjacent to cortical alveoli in the ooplasm of previtellogenic and vitellogenic oocytes. In zebrafish testes ( n = 3), mc4r and mc1r were detected exclusively in germ cells, specifically in spermatogonia and spermatocytes. Our results suggest that melanocortins are, directly or indirectly, involved in the endocrine control of vitellogenesis in females, through modulation of estradiol synthesis via autocrine or paracrine actions in zebrafish ovaries. Adult zebrafish testes were sensitive to low doses of ACTH, eliciting testosterone production, which indicates a potential role of this peptide as a paracrine regulator of testicular function.

Serotonin (5-HT) is one of the principal neurotransmitters in the nervous system of vertebrates. It is initially synthesized by hydroxylation of tryptophan (Trp) by means of tryptophan hydroxylase or TPH which is the rate-limiting enzyme in the production of 5-HT. In most vertebrates, there are two isoforms of TPH present, TPH1 and TPH2, which exhibit different catalytic or substrate specificity as well as different expression domains. Studies carried out in mammals show that only tph2 is expressed in the brain whereas tph1-mRNA is primarily localized in the enterochromaffin cells and pineal gland. A large number of neurons are also considered to be serotonergic or "pseudo-serotonergic" as they accumulate and release 5-HT yet do not produce it as no amine-synthetic enzymes are expressed, yet a combination of 5-HT transporters is observed. Therefore, tph expression is considered to be the only specific marker of 5-HT-producing neurons that can discriminate true 5-HT from pseudo-serotonergic neurons. This work examined in situ hybridization to study the mRNA distribution of one paralogue for tph1 and tph2 in the central nervous system of rainbow trout. Results show a segregated expression for both paralogues that predominantly match previous immunocytochemical studies. This study thus adds valuable information to the scarce analyses focusing on the central distribution of the expression of serotonergic markers, particularly tphs, in the vertebrate brain thus characterizing the true serotonergic brain territories., (© 2021. The Author(s).)

Resistin has been firstly discovered in mice and was identified as an adipose tissue-secreted hormone or adipokine linking obesity and insulin resistance. In humans, resistin has been characterized as a hormone expressed and secreted by Immune cells especially by macrophages, and was linked to many inflammatory responses including inflammation of adipose tissue due to macrophages' infiltration. Human and mouse resistin display sequence and structural similarities and also dissimilarities that could explain their different expression pattern. In mice, strong pieces of evidence clearly associated high resistin plasma levels to obesity and insulin resistance suggesting that resistin could play an important role in the onset and progression of obesity and insulin resistance via resistin-induced inflammation. In humans, the link between resistin and obesity/insulin resistance is still a matter of debate and needs more epidemiological studies. Also, resistin has been linked to other chronic diseases such as cardiovascular diseases and cancers where resistin has been proposed in many studies as a biological marker., (Copyright © 2021. Published by Elsevier B.V.)

Objective: Astrocytes are glial cells proposed as the main Sonic hedgehog (Shh)-responsive cells in the adult brain. Their roles in mediating Shh functions are still poorly understood. In the hypothalamus, astrocytes support neuronal circuits implicated in the regulation of energy metabolism. In this study, we investigated the impact of genetic activation of Shh signaling on hypothalamic astrocytes and characterized its effects on energy metabolism., Methods: We analyzed the distribution of gene transcripts of the Shh pathway (Ptc, Gli1, Gli2, and Gli3) in astrocytes using single molecule fluorescence in situ hybridization combined with immunohistofluorescence of Shh peptides by Western blotting in the adult mouse hypothalamus. Based on the metabolic phenotype, we characterized Glast-Cre ERT2 -YFP-Ptc -/- (YFP-Ptc -/- ) mice and their controls over time and under a high-fat diet (HFD) to investigate the potential effects of conditional astrocytic deletion of the Shh receptor Patched (Ptc) on metabolic efficiency, insulin sensitivity, and systemic glucose metabolism. Molecular and biochemical assays were used to analyze the alteration of key pathways modulating energy metabolism, insulin sensitivity, glucose uptake, and inflammation. Primary astrocyte cultures were used to evaluate a potential role of Shh signaling in astrocytic glucose uptake., Results: Shh peptides were the highest in the hypothalamic extracts of adult mice and a large population of hypothalamic astrocytes expressed Ptc and Gli1-3 mRNAs. Characterization of Shh signaling after conditional Ptc deletion in the YFP-Ptc -/- mice revealed heterogeneity in hypothalamic astrocyte populations. Interestingly, activation of Shh signaling in Glast + astrocytes enhanced insulin responsiveness as evidenced by glucose and insulin tolerance tests. This effect was maintained over time and associated with lower blood insulin levels and also observed under a HFD. The YFP-Ptc -/- mice exhibited a lean phenotype with the absence of body weight gain and a marked reduction of white and brown adipose tissues accompanied by increased whole-body fatty acid oxidation. In contrast, food intake, locomotor activity, and body temperature were not altered. At the cellular level, Ptc deletion did not affect glucose uptake in primary astrocyte cultures. In the hypothalamus, activation of the astrocytic Shh pathway was associated with the upregulation of transcripts coding for the insulin receptor and liver kinase B1 (LKB1) after 4 weeks and the glucose transporter GLUT-4 after 32 weeks., Conclusions: Here, we define hypothalamic Shh action on astrocytes as a novel master regulator of energy metabolism. In the hypothalamus, astrocytic Shh signaling could be critically involved in preventing both aging- and obesity-related metabolic disorders., Competing Interests: Conflicts of interest The authors have no competing interests to declare., (Copyright © 2021 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Saturated fatty acids such as palmitic acid promote inflammation and insulin resistance in peripheral tissues, contrasting with the protective action of polyunsaturated fatty acids such docosahexaenoic acid. Palmitic acid effects have been in part attributed to its potential action through Toll-like receptor 4. Beside, resistin, an adipokine, also promotes inflammation and insulin resistance via TLR4. In the brain, palmitic acid and resistin trigger neuroinflammation and insulin resistance, but their link at the neuronal level is unknown. Using human SH-SY5Yneuroblastoma cell line we show that palmitic acid treatment impaired insulin-dependent Akt and Erk phosphorylation whereas DHA preserved insulin action. Palmitic acid up-regulated TLR4 as well as pro-inflammatory cytokines IL6 and TNFα contrasting with DHA effect. Similarly to palmitic acid, resistin treatment induced the up-regulation of IL6 and TNFα as well as NFκB activation. Importantly, palmitic acid potentiated the resistin-dependent NFkB activation whereas DHA abolished it. The recruitment of TLR4 to membrane lipid rafts was increased by palmitic acid treatment; this is concomitant with the augmentation of resistin-induced TLR4/MYD88/TIRAP complex formation mandatory for TLR4 signaling. In conclusion, palmitic acid increased TLR4 expression promoting resistin signaling through TLR4 up-regulation and its recruitment to membrane lipid rafts.

Low-grade inflammation and insulin resistance are among the clinical features of obesity that are thought to promote the progressive onset of type 2 diabetes. However, the underlying mechanisms linking these disorders remain not fully understood. Recent reports pointed out hypothalamic inflammation as a major step in the onset of obesity-induced insulin resistance. In light of the increasing prevalence of obesity and T2D, two worldwide public health concerns, deciphering mechanisms implicated in hypothalamic inflammation constitutes a major challenge in the field of insulin-resistance/obesity. Several clinical and experimental studies have identified resistin as a key hormone linking insulin-resistance to obesity, notably through the activation of Toll Like Receptor (TLR) 4 signaling pathways. In this review, we present an overview of the molecular mechanisms underlying obesity-induced hypothalamic inflammation and insulin resistance with peculiar focus on the role of resistin/TLR4 signaling pathway.

Resistin promotes hypothalamic neuroinflammation and insulin resistance through Toll like receptor 4 (TLR4), this hormone is thought to be a link between obesity and insulin-resistance. Indeed, resistin plasma levels are higher in obese and insulin resistant subjects. However, the impact of maternal resistin on the predisposition of offspring to hypothalamic neuroinflammation is unknown. Here, female mice were treated with resistin during gestation/lactation periods, then hypothalamic neuroinflammation was investigated in male offspring at p28 and p90. At p28, resistin increased the expression of inflammation markers (IL6, TNFα and NFκB) and TLR4 in the hypothalamus and decreased both hypothalamic insulin and leptin receptors' expression. The hypothalamic up-regulation IL6, TNFα and TLR4 was sustained until p90 promoting most likely hypothalamic inflammation. Maternal resistin also increased IL6 and TNFα in the adipose tissue of offspring at p90 associated with a higher body weight gain. In contrast, liver and muscle were not affected. These findings reveal that the augmentation of maternal resistin during gestation and lactation promotes hypothalamic and adipose tissue inflammation of offspring as evidenced by sustained increase of inflammation markers from weaning to adulthood. Thus, maternal resistin programs offspring hypothalamic and adipose tissue inflammation predisposing then offspring to body weight gain., Competing Interests: The authors have declared that no competing interests exist.

Autophagy is a non-selective degradation pathway induced in energy-deprived cells and in non-starved cells by participating in cellular inflammatory responses mainly through the elimination of injured and aged mitochondria that constitute an important source of reactive oxygen species. We have previously reported that resistin/TLR4 signaling pathway induces inflammation and insulin resistance in neuronal cell. However, the impact of resistin-induced inflammation on neuronal autophagy is unknown. In the present study, we hypothesized that resistin-induced neuroinflammation could be attributed, at least partially, to the impairment of autophagy pathways in neuronal cells. Our data show that resistin decreases neuronal autophagy as evidenced by the repression of the main autophagy markers in SH-SY5Y human neuroblastoma cell line. Furthermore, the silencing of TLR4 completely abolished these effects. Resistin also inhibits AMPK phosphorylation and increases that of Akt/mTOR contrasting with activated autophagy where AMPK phosphorylation is augmented and mTOR inhibited. In vivo , resistin treatment inhibits the mRNA expression of autophagy markers in the hypothalamus of WT mice but not in Tlr4 -/- mice. In addition, resistin strongly diminished LC3 (a marker of autophagy) labeling in the arcuate nucleus of WT mice, and this effect is abolished in Tlr4 -/- mice. Taken together, our findings clearly reveal resistin/TLR4 as a new regulatory pathway of neuronal autophagy., (© 2018 Society for Endocrinology.)

Objectives: Hypothalamic lipotoxicity has been shown to induce central insulin resistance and dysregulation of glucose homeostasis; nevertheless, elucidation of the regulatory mechanisms remains incomplete. Here, we aimed to determine the role of de novo ceramide synthesis in hypothalamus on the onset of central insulin resistance and the dysregulation of glucose homeostasis induced by obesity., Methods: Hypothalamic GT1-7 neuronal cells were treated with palmitate. De novo ceramide synthesis was inhibited either by pharmacological (myriocin) or molecular (si-Serine Palmitoyl Transferase 2, siSPT2) approaches. Obese Zucker rats (OZR) were intracerebroventricularly infused with myriocin to inhibit de novo ceramide synthesis. Insulin resistance was determined by quantification of Akt phosphorylation. Ceramide levels were quantified either by a radioactive kinase assay or by mass spectrometry analysis. Glucose homeostasis were evaluated in myriocin-treated OZR. Basal and glucose-stimulated parasympathetic tonus was recorded in OZR. Insulin secretion from islets and β-cell mass was also determined., Results: We show that palmitate impaired insulin signaling and increased ceramide levels in hypothalamic neuronal GT1-7 cells. In addition, the use of deuterated palmitic acid demonstrated that palmitate activated several enzymes of the de novo ceramide synthesis pathway in hypothalamic cells. Importantly, myriocin and siSPT2 treatment restored insulin signaling in palmitate-treated GT1-7 cells. Protein kinase C (PKC) inhibitor or a dominant-negative PKCζ also counteracted palmitate-induced insulin resistance. Interestingly, attenuating the increase in levels of hypothalamic ceramides with intracerebroventricular infusion of myriocin in OZR improved their hypothalamic insulin-sensitivity. Importantly, central myriocin treatment partially restored glucose tolerance in OZR. This latter effect is related to the restoration of glucose-stimulated insulin secretion and an increase in β-cell mass of OZR. Electrophysiological recordings also showed an improvement of glucose-stimulated parasympathetic nerve activity in OZR centrally treated with myriocin., Conclusion: Our results highlight a key role of hypothalamic de novo ceramide synthesis in central insulin resistance installation and glucose homeostasis dysregulation associated with obesity., (Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.)

The effects of soybean meal (SBM) in early diet of Sparus aurata larvae at two developmental windows were assessed. Prolonged (beyond 14 days post-hatch, dph) feeding with SBM decreased the activity of pancreatic enzymes of larvae. In the absence of SBM these larvae later resumed enzyme activities, but exhibited a significant delay in development. Larvae response to SBM involved up-regulation of extracellular matrix remodeling enzymes and pro-inflammatory cytokines, coupled with a drop in putative intestinal enzymes. Larvae receiving SBM at first feeding appear later to have lower expression of inflammation-related genes, especially those fed SBM until 14 dph. Multivariate analysis confirmed that the duration of the SBM early feeding period drives the physiology of larvae in different directions. Feeding larvae with SBM increased global histone H3 acetylation, whereas upon removal of SBM the process was reverted. A more in deep analysis revealed a dynamic interplay among several reversible histone modifications such as H3K14ac and H3K27m3. Finally, we showed that SBM feeding of larvae results in global hypomethylation that persist after SBM removal. This study is the first demonstrating an effect of diet on marine fish epigenetics. It is concluded that there are limitations for extending SBM feeding of S. aurata larvae beyond 14 dph even under co-feeding with live feed, affecting key physiological processes and normal growth. However, up to 14 dph, SBM does not affect normal development, and produces apparently lasting effects on some key enzymes, genes, and chromatin modifications.

The brain is considered a major site for microRNA (miRNA) expression; as evidenced by several studies reporting microarray data of different brain substructures. The hypothalamus is among the brain regions that plays a crucial role in integrating signals from other brain nuclei as well as environmental, hormonal, metabolic and neuronal signals from the periphery in order to deliver an adequate response. The hypothalamus controls vital functions such as reproduction, energy homeostasis, water balance, circadian rhythm and stress. These functions need a high neuronal plasticity to adequately respond to physiological, environmental and psychological stimuli that could be limited to a specific temporal period during life or are cyclic events. In this context, miRNAs constitute major regulators and coordinators of gene expression. Indeed, in response to specific stimuli, changes in miRNA expression profiles finely tune specific mRNA targets to adequately fit to the immediate needs through mainly the modulation of neuronal plasticity., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Organisms are surrounded throughout life by chemically complex odors. How individuals process an odorant within a mixture or a mixture as a whole is a key question in neuroethology and chemical senses. This question is addressed here by using newborn rabbits, which can be rapidly conditioned to a new stimulus by single association with the mammary pheromone. After conditioning to ethyl maltol (odorant B), pups behaviorally respond to B and an A'B' mixture (68/32 ratio) but not to ethyl isobutyrate (odorant A) or an AB mixture (30/70 ratio). This suggests elemental and configural perception of A'B' and AB, respectively. We then explored the neural substrates underlying the processing of these mixtures with the hypothesis that processing varies according to perception. Pups were pseudoconditioned or conditioned to B on postnatal day 3 before exposure to B, A'B' or AB on day 4. Fos expression was not similar between groups (mainly in the olfactory bulb and posterior piriform cortex) suggesting a differential processing of the stimuli that might reflect either stimulus complexity or conditioning effect. Thus, the ratio of components in A'B' vs AB leads to differential activation of the olfactory system which may contribute to elemental and configural percepts of these mixtures. In addition, together with recent behavioral data, this highlights that configural perception occurs even in relatively immature animals, emphasizing the value of the newborn rabbit for exploration of odor mixture processing from molecules to brain and behavior.

Melanocortin signaling is regulated by the binding of naturally occurring antagonists, agouti-signaling protein (ASIP) and agouti-related protein (AGRP) that compete with melanocortin peptides by binding to melanocortin receptors to regulate energy balance and growth. Using a transgenic model overexpressing ASIP, we studied the involvement of melanocortin system in the feeding behaviour, growth and stress response of zebrafish. Our data demonstrate that ASIP overexpression results in enhanced growth but not obesity. The differential growth is explained by increased food intake and feeding efficiency mediated by a differential sensitivity of the satiety system that seems to involve the cocaine- and amphetamine- related transcript (CART). Stress response was similar in both genotypes. Brain transcriptome of transgenic (ASIP) vs wild type (WT) fish was compared using microarrays. WT females and males exhibited 255 genes differentially expressed (DEG) but this difference was reduced to 31 after ASIP overexpression. Statistical analysis revealed 1122 DEG when considering only fish genotype but 1066 and 981 DEG when comparing ASIP males or females with their WT counterparts, respectively. Interaction between genotype and sex significantly affected the expression of 97 genes. Several neuronal systems involved in the control of food intake were identified which displayed a differential expression according to the genotype of the fish that unravelling the flow of melanocortinergic information through the central pathways that controls the energy balance. The information provided herein will help to elucidate new central systems involved in control of obesity and should be of invaluable use for sustaining fish production systems., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Proopiomelanocortin (POMC) is a complex precursor that comprises several peptidic hormones, including melanocyte-stimulating hormones (MSHs), adrenocorticotropic hormone (ACTH), and β-endorphin. POMC belongs to the opioid/orphanin gene family, whose precursors include either opioid (YGGF) or the orphanin/nociceptin core sequences (FGGF). This gene family diversified during early tetraploidizations of the vertebrate genome to generate four different precursors: proenkephalin (PENK), prodynorphin (PDYN), and nociceptin/proorphanin (PNOC) as well as POMC, although both PNOC and POMC seem to have arisen due to a local duplication event. POMC underwent complex evolutionary processes, including internal tandem duplications and putative coevolutionary events. Controversial and conflicting hypotheses have emerged concerning the sequenced genomes. In this article, we summarize the different evolutionary hypotheses proposed for POMC evolution., (© 2016 Society for Endocrinology.)

Adiponectin, an insulin-sensitizing hormone, and resistin, known to promote insulin resistance, constitute a potential link between obesity and type 2 diabetes. In addition, fibroblast growth factor (FGF)21 has effects similar to those of adiponectin in regulating glucose and lipid metabolism and insulin sensitivity. However, the interplay between adiponectin, FGF21, and resistin signaling pathways during the onset of insulin resistance is unknown. Here, we investigated whether central resistin promotes insulin resistance through the impairment of adiponectin and FGF21 signaling. We show that chronic intracerebroventricular resistin infusion downregulated both hypothalamic and hepatic APPL1, a key protein in adiponectin signaling, associated with decreased Akt-APPL1 interaction and an increased Akt association with its endogenous inhibitor tribbles homolog 3. Resistin treatment also decreased plasma adiponectin levels and reduced both hypothalamic and peripheral expression of adiponectin receptors. Additionally, we report that intracerebroventricular resistin increased plasma FGF21 levels and downregulated its receptor components in the hypothalamus and peripheral tissues, promoting FGF21 resistance. Interestingly, we also show that resistin effects were abolished in TLR4 knockout mice and in neuronal cells expressing TLR4 siRNAs. Our study reveals a novel mechanism of insulin resistance onset orchestrated by a central resistin-TLR4 pathway that impairs adiponectin signaling and promotes FGF21 resistance., (© 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.)

SPARC/osteonectin is a multifunctional matricellular glycoprotein, which is expressed in embryonic and adult tissues that undergo active proliferation and dynamic morphogenesis. Recent studies indicate that Sparc expression appears early in development, although its function and regulation during development are largely unknown. In this report, we describe the isolation, characterization, post-embryonic developmental expression and environmental thermal regulation of sparc in turbot. The full-length turbot sparc cDNA contains 930 bp and encodes a protein of 310 amino acids, which shares 77, 75 and 80% identity with human, frog and zebrafish, respectively. Results of whole-mount in situ hybridization reveal a dynamic expression profile during post-embryonic turbot development. Sparc is expressed differentially in the cranioencephalic region; mainly in jaws, branchial arches, fin folds and rays of caudal, dorsal and anal fins. Furthermore, ontogenetic studies demonstrated that Sparc gene expression is dynamically regulated during post-embryonic turbot development, with high expression during stage-specific post-embryonic remodeling. Additionally, the effect of thermal environmental conditions on turbot development and on ontogenetic sparc expression was evaluated., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Acute changes in diet composition and/or origin alter gastric emptying and gastrointestinal motility. One of the hypotheses explaining these alterations involves changes in the sensitivity of duodenal vagal sensory neurons. The aim of this study was to evaluate the characteristics of multimodal duodenal vagal sensory neurons in 20 pigs feed either with milk-based or plant-based diets of identical caloric content. Twenty duodenal vagal afferents were recorded in anesthetized animal from the cervical vagus using the single fiber method. 10 pigs were fed with a milk-based diet (MD) for one month while the diet of the 10 other pigs was changed for plant-based diet (PD) the day preceding the recording session. The behavior of the receptors was tested in basal resting conditions and after challenges with duodenal intralipid and close intra-arterial injection of CCK, 5-HT or capsaicin with and without isovolumetric duodenal distensions at 20, 40 and 60 mmHg. All receptors were slowly adapting C type fiber with a receptor field located 6-7 cm distal to the pylorus. The rate of discharge during distension (20, 40 and 60 mmHg) combined with duodenal intralipid was significantly larger for MD compared with PD. Similarly, the rate of discharge observed during distensions performed with CCK and with 5-HT were greater for MD compared with PD while CCK and 5-HT without distension were equally stimulating for MD and PD. No significant difference was found between groups during capsaicin infusion irrespective of the stimulating pressure. In conclusion, a switch to plant-based diet, when compared to a milk-based diet, results in an overall decrease in mechanical sensitivity of duodenal neurons during lipid, 5HT and CCK challenges, but not in basal conditions or after capsaicin. This reduced sensitivity to distension may explain the diet-induced alteration of gastric emptying that is controlled primarily through a vago-vagal reflex.

The anterior piriform cortex (APC) of the rat is thought to be the site of indispensable amino acid (IAA) chemosensation in the brain. The branched-chain amino acids, including leucine, are among the IAA that are recognized in the APC. The behavioral outcome of IAA deficiency is an anorectic response. The specific transduction mechanisms by which IAA deficiency and repletion activate the APC are not fully understood, but clearly phosphorylation of proteins, increases in intracellular calcium, and expression of the immediate early gene c-fos, which are among the earliest events occurring after the initial drop in the concentration of the limiting IAA, cause stimulation in the APC. Subsequently, several neurotransmitter systems, including those for norepinephrine, GABA, serotonin, dopamine and nitric oxide, are activated in the APC of rats that have consumed an IAA-imbalanced diet. These systems appear to modulate the output cells from the APC, glutamatergic pyramidal cells that send neural signals to activate subsequent relays in the brain. Ultimately, the feeding circuits of the brain carry out the anorectic response. Continued consumption of a diet containing an IAA imbalance causes a conditioned taste aversion to the diet in all animals that have been studied. Such learning involves synaptic reorganization, requiring both degradation and synthesis of protein, along with alterations in genomic activity.

Expression of c-fos is increased in the central amygdaloid nucleus (CE) of rats ingesting a diet with a severely imbalanced essential amino acid profile (IMB), at a time associated with development of a conditioned taste aversion (CTA). The CE and the basolateral amygdaloid nucleus (BL) both are reported to be involved in the development of CTA. Large amygdaloid lesions involving CE and BL mitigate the normal decrease in intake of IMB; this treatment also impairs CTA to a flavor cue associated with gastrointestinal discomfort. To differentiate their potential roles in aversive responses to IMB, we electrolytically lesioned CE and BL separately. Neither lesion attenuated IMB-induced anorexia, or prevented the avoidance of flavored solutions previously paired with IMB. In contrast, after saccharin-LiCl pairing, CE-lesioned animals showed attenuated CTA to saccharin solution in a two-bottle test. We conclude that neither the CE nor the BL is essential for the reduction of IMB intake, or for CTA associated with IMB. Furthermore, these results suggest that the aversive consequences of IMB intake do not involve gastrointestinal malaise-evoked neurotransmission involving the CE.

Previous work from this laboratory suggests that animals decrease their intake of an amino acid imbalanced diet (IMB), due in part to a drop in the concentration of the dietary limiting amino (DLAA) in the anterior piriform cortex (APC). Administration of the DLAA, but not of a non-limiting amino acid into the APC, blocks the anorectic response to IMB. To our knowledge, the effects of DLAA injections on intake of a diet devoid of the DLAA (DEV), have not been examined in areas outside the APC. We hypothesized that the LH is a potential chemosensory area for DLAA. Our objectives were: (1) to determine whether injections of the DLAA threonine into the lateral hypothalamus (LH) alter intake of a threonine-devoid diet (DEV); and (2) to examine the dose-response effects of threonine injections into the LH on intake of threonine-corrected diet (COR). Administration of threonine into the LH stimulated DEV intake during the first 6 h at the 0.25 and 1-nmol doses by approximately 26 and 24%, respectively. Threonine (0.25, 2.5 nmol) did not alter COR intake at any time during the first 12 h. Our results suggest that: (1) the LH, along with the APC, likely acts as a chemosensory brain area for indispensable amino acids; and (2) both the APC and LH are part of a circuit that is involved in the short term anorectic response to amino acid imbalanced diets.

Both total subdiaphragmatic vagotomy (TVAGX) and serotonin(3) receptor blockade with tropisetron or ondansetron attenuate amino acid-imbalanced diet (Imb) anorexia. Total vagotomy is less effective than tropisetron in reducing Imb-induced anorexia and also blunts the tropisetron effect. With the use of electrocautery at the subdiaphragmatic level of the vagus, we severed the ventral and dorsal trunks as well as the hepatic, ventral gastric, dorsal gastric, celiac, and accessory celiac branches separately or in combination to determine which vagal branches or associated structures may be involved in these responses. Rats were prefed a low-protein diet. On the first experimental day, tropisetron or saline was given intraperitoneally 1 h before presentation of Imb. Cuts including the ventral branch, i.e., TVAGX, ventral vagotomy (above the hepatic branch), and hepatic + gastric vagotomies (but not hepatic branch cuts alone) caused the highest (P < 0.05) Imb intake on day 1 with or without tropisetron. The responses to tropisetron were not affected significantly. On days 2-8, groups having vagotomies that included the hepatic branch recovered faster than sham-treated animals. Because the hepatic and gastric branches together account for most of the vagal innervation to the proximal duodenum, this area may be important in the initial responses, whereas structures served by the hepatic branch alone apparently act in the later adaptation to Imb.

The anterior piriform cortex (APC) is essential for the anorectic reactions to an amino acid-imbalanced diet, and it also responds to repletion of the limiting amino acid. In the present study, we examine the dynamic changes of the interstitial dopamine metabolites in the APC following feeding of either an amino acid-corrected or -imbalanced diet. Microdialysates, collected from the APC, were analyzed using HPLC with electrochemical detection. The concentrations were 19.7 +/- 4.8 microg/L for 3, 4-dyhydroxyphenylacetic acid and 25.1 +/- 4.4 microg/L for homovanillic acid, respectively, in the baseline dialysates. After diet treatments, no significant changes occurred in 3, 4-dyhydroxyphenylacetic acid in the corrected (n = 7) or imbalanced (n = 9) groups vs. the basal group (n = 7). However, after feeding the threonine-corrected diet, the concentration of homovanillic acid was significantly less (P < 0.01) than after the basal and imbalanced diets. The homovanillic acid level in the corrected group was already significantly lower than in the basal group by 20 min (P < 0.05), and reached its lowest level at 70 min (P < 0.05). The concentrations of homovanillic acid in the corrected group remained at this low level until the end of the experiment. The present results introduce the idea that the dopaminergic system is involved in the feeding responses to essential amino acid repletion.

The anterior piriform cortex (APC) may serve as the chemosensor for amino acid (AA) deficiency in rats. To investigate the mechanism by which the APC recognizes a limiting indispensable AA (IAA), we examined changes in intracellular calcium ([Ca2+]i) in APC slices after culture in medium with or without threonine (Thr) or lysine (Lys). The addition of 1 or 10 mM Thr to slices previously incubated in Thr-devoid medium resulted in a significant and sustained increase in [Ca2+]i compared to control slices; an effect not seen when isoleucine, another IAA, was added. Similar results were seen when lysine, but not threonine, was added to slices incubated in lysine-devoid medium. The rise in [Ca2+]i resulting from the addition of the limiting IAA to deficient slices may be linked to enhanced activity of the appropriate AA transporter. This is suggested by preliminary findings that serine, a small neutral AA that uses the same transporter as threonine, gave rise to an enhanced response in the Thr-deficient slice.

Leptin administered intracerebroventricularly (ICV) or intrahypothalamically inhibits food intake (FI), however, to our knowledge the effects of leptin administration have only been examined in one extrahypothalamic site (dorsal raphe nucleus). Our objectives were t. (1) determine the FI effects of leptin administration into the anterior piriform cortex (APC), an area linked to the control of FI in amino acid (AA) deficiency, (2) examine leptin action during short term anorexia that develops in response to AA deficiency. Bilateral injections of leptin (0.25 μ) into the APC suppressed FI of a balanced diet between 6 and 12 h by 36% (p < 0.01) and over the first 12 and 24 h by 15% (p < 0.05). Bilateral administration of leptin (0.1 μg) inhibited FI between 12 and 24 h by approximately 48% (p < 0.05) on a threonine-imbalanced diet without significantly affecting FI on a threonine-corrected diet. The increase of plasma leptin concentrations in response to feeding a threonine-basal diet was greater than that following an AA imbalanced diet, suggesting that suppression of FI by an AA imbalanced diet is not mediated by an increase of leptin. Our results suggest that (1) administration of leptin into a brain area outside the hypothalamus suppresses FI, and (2) leptin is unlikely to play a selective role in the short term anorectic response to AA deficiency. These data are consistent with the hypothesis that endogenous leptin can act within the APC to modulate FI.

Neuropeptides affect food intake via peripheral and brainstem mechanisms, but their roles in mediating feeding via the cerebral cortex have received little attention. The anterior piriform cortex (APC) appears to play a critical role in neuroperception of deficiencies of essential amino acids (AA) and the anorectic response to such deficiencies. The neural circuitry underlying the role of this paleocortex in these events is not understood. We have shown that neurons containing neuropeptide Y (NPY) and somatostatin (SOM) are cytoarchitecturally in positions to relate synaptically to the neurons of the APC which may mediate responses to AA. Thus, we hypothesized that NPY and SOM administered intracortically to the APC would directly affect food intake in a threonine-imbalanced model. We determined that NPY at 1-1.5 nmol decreased intake of the AA-deficient diet for 3 h, with a cumulative effect that extended through 6 h. SOM had a dual effect; at 1 pmol it increased intake of the AA-deficient diet for 3 h; at 2 nmol, SOM decreased intake of the AA-deficient diet for over 9 h, with a cumulative effect that persisted through 12 h. In the first 3 h, intake of animals receiving 1 pmol of SOM differed significantly from those receiving 2 nmol. These results suggest that NPY and SOM affect the cortical circuitry responsible for recognition of deficiencies in nutritionally essential AA, and that the timing of the cortical responses to the peptides may be related to the time course of the anorectic responses.

Rats offered an amino acid-imbalanced diet (IMB) respond to the ensuing amino acid deficiency rapidly with a decrease in food intake of at least 50%. Pretreatment with tropisetron (TROP), an antagonist at serotonin3 (5-HT3) and 5-HT4 receptors, increases intake of IMB to approximately 85% of control. Vagotomy has two effects: it increases intake of an IMB to about 65%, and also blocks the increased response to tropisetron. This indicates that the greater IMB intake after tropisetron, approximately 20% more than in vagotomized rats, is dependent on an intact vagus. Rats were either 1) vagotomized or sham-operated, or 2) given tropisetron or saline injections. We then examined free-feeding meal patterns in rats fed an IMB to determine whether the microstructure of the feeding behavior differed, either between treatments, or by comparison with the meal patterns in rats fed the control diet. Vagotomy did not alter meal patterns in rats consuming the basal control diet. During the first 6 h after introduction of the IMB, the control rats showed significantly longer intermeal intervals (over twice the length of intervals recorded in those fed the basal diet), with corresponding effects on meal numbers, which were restored to basal values in tropisetron and vagotomized rats. Meal size was increased after vagotomy also. After 6 h, in intact tropisetron-treated rats only, a fourfold faster rate of eating throughout the late dark period accounted for the significantly greater intake of the IMB than in controls. The results demonstrated differential effects of the two treatments on the anorectic responses to amino acid deficiency.

The responses of the brain to the amino acid deficiency that occur after eating imbalanced amino acid diets (IMB) have been associated with decreased concentrations of norepinephrine (NE) and cAMP in the anterior piriform cortex (APC), an area essential for the initial feeding responses to amino acid deficiency. In addition, the anorectic responses to IMB were decreased after injections of the alpha 2 agonist, clonidine, and increased after injections of the alpha 2 antagonist, idazoxan, into the APC. Therefore, to study the role of the alpha 2-noradrenergic receptor further in this model, we measured alpha 2-noradrenergic receptor binding in the APC of rats fed two levels of threonine IMB or a low-protein basal control diet. After basal prefeeding for 10 days, rats were given either a mild IMB, a severe IMB, or the basal diet for 2.5 h. The APC, anterior cingulate cortex (AC), ventromedial hypothalamus (VMH), and lateral hypothalamus (LH) were assayed. Binding of [3H]p-aminoclonidine to alpha 2 receptors determined that alpha 2 binding was decreased the most in APC (P < 0.0003). Binding in APC was significantly correlated with food intake in the anorectic response to IMB (P < 0.001). In AC, binding was also significantly decreased, but less dramatically (P = 0.012), and was not correlated with food intake. There were no significant changes in LH or VMH, although alpha 2-noradrenergic binding in VMH tended to decrease with the severe IMB in a pattern similar to APC. Plasma glucose values did not differ after the same feeding protocol. These data support our hypothesis that NE activity in the APC plays a role in initiating the anorectic response to IMB, perhaps via the alpha 2-noradrenergic receptor.

It has long been known that the central nervous system (CNS) directly affects pancreatic insulin release. This study was undertaken to determine the effect of the CNS on pancreatic insulin release in three-month-old female lean (Fa/Fa) and hyperinsulinemic obese (fa/fa) Zucker rats. Chloral hydrate (400 mg/kg) was used as the anesthetic agent. The in situ brain-pancreas perfusion model with intact pancreatic innervation was used in this investigation. The study measured insulin secretion in response to a 60-minute glucose stimulus (200 mg/dl). CNS-intact and CNS-functionally ablated obese and lean rats were used. During the 60-minute perfusion period significantly more insulin was released by pancreata from obese rats compared to those from lean rats. In lean rats, about twice as much insulin was released by pancreata from CNS-ablated rats than from CNS-intact rats (P < 0.05), demonstrating a CNS tonic inhibition of insulin secretion. In obese rats, there was no significant difference in insulin released by the pancreata of the CNS-intact and CNS-ablated rats. To determine if there was a masking effect of predominant PNS activity over the SNS in the CNS-intact obese rats, bilateral vagotomy was performed in a group of otherwise CNS-intact obese rats prior to the onset of perfusion. Tonic inhibition was still not observed in the CNS-vagotomized obese rats. In conclusion, hypersecretion of insulin in obese rats is partially due to diminished tonic sympathetic nervous system inhibition of insulin release. These results provide additional evidence regarding abnormal CNS control of insulin secretion in obese Zucker rats.

The association among changes in glucose status, glutamate decarboxylase (GAD) activity, and food intake was evaluated in several hypothalamic areas of streptozotocin-diabetic rats fed a low- (12% of calories as fat) or high-fat diet (59% of calories as fat). Control rats consumed approximately 90 kcal/24 h of either diet, whereas diabetic rats consumed approximately 150 kcal/24 h of the low-fat diet and approximately 100 kcal/24 h of the high-fat diet. At the end of the study, diabetic rats fed the high-fat diet weighed more and had higher retroperitoneal fat depot weights (P less than 0.05) than diabetic rats fed the low-fat diet. In diabetic rats, GAD activity was 15-20% higher in the ventromedial nucleus (P less than 0.01) but similar to controls in the lateral hypothalamus, paraventricular nucleus, and area postrema. Diet did not affect GAD activity in the brain areas studied. The increase in ventromedial nucleus GAD activity was not associated with the level of food intake and was the likely result of altered glucose homeostasis in diabetic rats.

Changes in the activity of glutamate decarboxylase (GAD), the rate-limiting enzyme in gamma-aminobutyric acid synthesis, in response to insulin-induced hypoglycemia were measured in several brain areas involved in glucoregulation. A 20% increase in GAD activity in the ventromedial nucleus (VMN) of rats was measured 30 min after injections of insulin. The increase was significantly correlated with the decrease in serum glucose (r = -0.74) and increased food intake (r = 0.44). The increase in VMN GAD activity was linear between 5 and 30 min after insulin injection and coincided with the decline in serum glucose. Pretreatment with a gastric preload of a 50% glucose solution attenuated the decline in serum glucose, the increase in food intake, and the increase in GAD activity. Inhibition of protein synthesis by puromycin did not block the decrease in glucose, but neither the increase in GAD activity in the VMN nor the increase in food intake in response to insulin was observed. The increase in VMN GAD activity also was present 6 h after insulin injection if rats were denied access to food. No consistent changes in GAD activity were measured in any brain area other than the VMN. The results of these trials suggest that the increase in VMN GAD activity is associated with the decrease in serum glucose and may be involved in the increased feeding associated with insulin administration.