Science.gov

Sample records for hypothalamic leucine sensing

  1. Hypothalamic Leucine Metabolism Regulates Liver Glucose Production

    PubMed Central

    Su, Ya; Lam, Tony K.T.; He, Wu; Pocai, Alessandro; Bryan, Joseph; Aguilar-Bryan, Lydia; Gutiérrez-Juárez, Roger

    2012-01-01

    Amino acids profoundly affect insulin action and glucose metabolism in mammals. Here, we investigated the role of the mediobasal hypothalamus (MBH), a key center involved in nutrient-dependent metabolic regulation. Specifically, we tested the novel hypothesis that the metabolism of leucine within the MBH couples the central sensing of leucine with the control of glucose production by the liver. We performed either central (MBH) or systemic infusions of leucine in Sprague-Dawley male rats during basal pancreatic insulin clamps in combination with various pharmacological and molecular interventions designed to modulate leucine metabolism in the MBH. We also examined the role of hypothalamic ATP-sensitive K+ channels (KATP channels) in the effects of leucine. Enhancing the metabolism of leucine acutely in the MBH lowered blood glucose through a biochemical network that was insensitive to rapamycin but strictly dependent on the hypothalamic metabolism of leucine to α-ketoisocaproic acid and, further, insensitive to acetyl- and malonyl-CoA. Functional KATP channels were also required. Importantly, molecular attenuation of this central sensing mechanism in rats conferred susceptibility to developing hyperglycemia. We postulate that the metabolic sensing of leucine in the MBH is a previously unrecognized mechanism for the regulation of hepatic glucose production required to maintain glucose homeostasis. PMID:22187376

  2. Oral Leucine Supplementation Is Sensed by the Brain but neither Reduces Food Intake nor Induces an Anorectic Pattern of Gene Expression in the Hypothalamus

    PubMed Central

    Zampieri, Thais T.; Pedroso, João A. B.; Furigo, Isadora C.; Tirapegui, Julio; Donato, Jose

    2013-01-01

    Leucine activates the intracellular mammalian target of the rapamycin (mTOR) pathway, and hypothalamic mTOR signaling regulates food intake. Although central infusion of leucine reduces food intake, it is still uncertain whether oral leucine supplementation is able to affect the hypothalamic circuits that control energy balance. We observed increased phosphorylation of p70s6k in the mouse hypothalamus after an acute oral gavage of leucine. We then assessed whether acute oral gavage of leucine induces the activation of neurons in several hypothalamic nuclei and in the brainstem. Leucine did not induce the expression of Fos in hypothalamic nuclei, but it increased the number of Fos-immunoreactive neurons in the area postrema. In addition, oral gavage of leucine acutely increased the 24 h food intake of mice. Nonetheless, chronic leucine supplementation in the drinking water did not change the food intake and the weight gain of ob/ob mice and of wild-type mice consuming a low- or a high-fat diet. We assessed the hypothalamic gene expression and observed that leucine supplementation increased the expression of enzymes (BCAT1, BCAT2 and BCKDK) that metabolize branched-chain amino acids. Despite these effects, leucine supplementation did not induce an anorectic pattern of gene expression in the hypothalamus. In conclusion, our data show that the brain is able to sense oral leucine intake. However, the food intake is not modified by chronic oral leucine supplementation. These results question the possible efficacy of leucine supplementation as an appetite suppressant to treat obesity. PMID:24349566

  3. Hypothalamic glucose sensing: making ends meet

    PubMed Central

    Routh, Vanessa H.; Hao, Lihong; Santiago, Ammy M.; Sheng, Zhenyu; Zhou, Chunxue

    2014-01-01

    The neuroendocrine system governs essential survival and homeostatic functions. For example, growth is needed for development, thermoregulation maintains optimal core temperature in a changing environment, and reproduction ensures species survival. Stress and immune responses enable an organism to overcome external and internal threats while the circadian system regulates arousal and sleep such that vegetative and active functions do not overlap. All of these functions require a significant portion of the body's energy. As the integrator of the neuroendocrine system, the hypothalamus carefully assesses the energy status of the body in order to appropriately partition resources to provide for each system without compromising the others. While doing so the hypothalamus must ensure that adequate glucose levels are preserved for brain function since glucose is the primary fuel of the brain. To this end, the hypothalamus contains specialized glucose sensing neurons which are scattered throughout the nuclei controlling distinct neuroendocrine functions. We hypothesize that these neurons play a key role in enabling the hypothalamus to partition energy to meet these peripheral survival needs without endangering the brain's glucose supply. This review will first describe the varied mechanisms underlying glucose sensing in neurons within discrete hypothalamic nuclei. We will then evaluate the way in which peripheral energy status regulates glucose sensitivity. For example, during energy deficit such as fasting specific hypothalamic glucose sensing neurons become sensitized to decreased glucose. This increases the gain of the information relay when glucose availability is a greater concern for the brain. Finally, changes in glucose sensitivity under pathological conditions (e.g., recurrent insulin-hypoglycemia, diabetes) will be addressed. The overall goal of this review is to place glucose sensing neurons within the context of hypothalamic control of neuroendocrine function

  4. L-leucine supplementation worsens the adiposity of already obese rats by promoting a hypothalamic pattern of gene expression that favors fat accumulation.

    PubMed

    Zampieri, Thais T; Torres-Leal, Francisco L; Campaña, Amanda B; Lima, Fabio B; Donato, Jose

    2014-04-02

    Several studies showed that l-leucine supplementation reduces adiposity when provided before the onset of obesity. We studied rats that were exposed to a high-fat diet (HFD) for 10 weeks before they started to receive l-leucine supplementation. Fat mass was increased in l-leucine-supplemented rats consuming the HFD. Accordingly, l-leucine produced a hypothalamic pattern of gene expression that favors fat accumulation. In conclusion, l-leucine supplementation worsened the adiposity of rats previously exposed to HFD possibly by central mechanisms.

  5. Enhanced hypothalamic glucose sensing in obesity: alteration of redox signaling.

    PubMed

    Colombani, Anne-Laure; Carneiro, Lionel; Benani, Alexandre; Galinier, Anne; Jaillard, Tristan; Duparc, Thibaut; Offer, Géraldine; Lorsignol, Anne; Magnan, Christophe; Casteilla, Louis; Pénicaud, Luc; Leloup, Corinne

    2009-10-01

    Recent data demonstrated that glucose sensing in different tissues is initiated by an intracellular redox signaling pathway in physiological conditions. However, the relevance of such a mechanism in metabolic disease is not known. The aim of the present study was to determine whether brain glucose hypersensitivity present in obese Zücker rats is related to an alteration in redox signaling. Brain glucose sensing alteration was investigated in vivo through the evaluation of electrical activity in arcuate nucleus, changes in reactive oxygen species levels, and hypothalamic glucose-induced insulin secretion. In basal conditions, modifications of redox state and mitochondrial functions were assessed through oxidized glutathione, glutathione peroxidase, manganese superoxide dismutase, aconitase activities, and mitochondrial respiration. Hypothalamic hypersensitivity to glucose was characterized by enhanced electrical activity of the arcuate nucleus and increased insulin secretion at a low glucose concentration, which does not produce such an effect in normal rats. It was associated with 1) increased reactive oxygen species levels in response to this low glucose load, 2) constitutive oxidized environment coupled with lower antioxidant enzyme activity at both the cellular and mitochondrial level, and 3) overexpression of several mitochondrial subunits of the respiratory chain coupled with a global dysfunction in mitochondrial activity. Moreover, pharmacological restoration of the glutathione hypothalamic redox state by reduced glutathione infusion in the third ventricle fully reversed the cerebral hypersensitivity to glucose. The data demonstrated that obese Zücker rats' impaired hypothalamic regulation in terms of glucose sensing is linked to an abnormal redox signaling, which originates from mitochondria dysfunction.

  6. Structural basis for leucine sensing by the Sestrin2-mTORC1 pathway

    SciTech Connect

    Saxton, Robert A.; Knockenhauer, Kevin E.; Wolfson, Rachel L.; Chantranupong, Lynne; Pacold, Michael E.; Wang, Tim; Schwartz, Thomas U.; Sabatini, David M.

    2015-11-19

    Eukaryotic cells coordinate growth with the availability of nutrients through mTOR complex 1 (mTORC1), a master growth regulator. Leucine is of particular importance and activates mTORC1 via the Rag GTPases and their regulators GATOR1 and GATOR2. Sestrin2 interacts with GATOR2 and is a leucine sensor. We present the 2.7-Å crystal structure of Sestrin2 in complex with leucine. Leucine binds through a single pocket that coordinates its charged functional groups and confers specificity for the hydrophobic side chain. A loop encloses leucine and forms a lid-latch mechanism required for binding. A structure-guided mutation in Sestrin2 that decreases its affinity for leucine leads to a concomitant increase in the leucine concentration required for mTORC1 activation in cells. Lastly, these results provide a structural mechanism of amino acid sensing by the mTORC1 pathway.

  7. Structural basis for leucine sensing by the Sestrin2-mTORC1 pathway

    PubMed Central

    Saxton, Robert A.; Knockenhauer, Kevin E.; Wolfson, Rachel L.; Chantranupong, Lynne; Pacold, Michael E.; Wang, Tim; Schwartz, Thomas U.; Sabatini, David M.

    2015-01-01

    Eukaryotic cells coordinate growth with the availability of nutrients through mTOR complex 1 (mTORC1), a master growth regulator. Leucine is of particular importance and activates mTORC1 via the Rag GTPases and their regulators GATOR1 and GATOR2. Sestrin2 interacts with GATOR2 and is a leucine sensor. We present the 2.7-Å crystal structure of Sestrin2 in complex with leucine. Leucine binds through a single pocket that coordinates its charged functional groups and confers specificity for the hydrophobic side chain. A loop encloses leucine and forms a lid-latch mechanism required for binding. A structure-guided mutation in Sestrin2 that decreases its affinity for leucine leads to a concomitant increase in the leucine concentration required for mTORC1 activation in cells. These results provide a structural mechanism of amino acid sensing by the mTORC1 pathway. PMID:26586190

  8. Structural basis for leucine sensing by the Sestrin2-mTORC1 pathway.

    PubMed

    Saxton, Robert A; Knockenhauer, Kevin E; Wolfson, Rachel L; Chantranupong, Lynne; Pacold, Michael E; Wang, Tim; Schwartz, Thomas U; Sabatini, David M

    2016-01-01

    Eukaryotic cells coordinate growth with the availability of nutrients through the mechanistic target of rapamycin complex 1 (mTORC1), a master growth regulator. Leucine is of particular importance and activates mTORC1 via the Rag guanosine triphosphatases and their regulators GATOR1 and GATOR2. Sestrin2 interacts with GATOR2 and is a leucine sensor. Here we present the 2.7 angstrom crystal structure of Sestrin2 in complex with leucine. Leucine binds through a single pocket that coordinates its charged functional groups and confers specificity for the hydrophobic side chain. A loop encloses leucine and forms a lid-latch mechanism required for binding. A structure-guided mutation in Sestrin2 that decreases its affinity for leucine leads to a concomitant increase in the leucine concentration required for mTORC1 activation in cells. These results provide a structural mechanism of amino acid sensing by the mTORC1 pathway.

  9. Enhanced Hypothalamic Glucose Sensing in Obesity: Alteration of Redox Signaling

    PubMed Central

    Colombani, Anne-Laure; Carneiro, Lionel; Benani, Alexandre; Galinier, Anne; Jaillard, Tristan; Duparc, Thibaut; Offer, Géraldine; Lorsignol, Anne; Magnan, Christophe; Casteilla, Louis; Pénicaud, Luc; Leloup, Corinne

    2009-01-01

    OBJECTIVE Recent data demonstrated that glucose sensing in different tissues is initiated by an intracellular redox signaling pathway in physiological conditions. However, the relevance of such a mechanism in metabolic disease is not known. The aim of the present study was to determine whether brain glucose hypersensitivity present in obese Zücker rats is related to an alteration in redox signaling. RESEARCH DESIGN AND METHODS Brain glucose sensing alteration was investigated in vivo through the evaluation of electrical activity in arcuate nucleus, changes in reactive oxygen species levels, and hypothalamic glucose-induced insulin secretion. In basal conditions, modifications of redox state and mitochondrial functions were assessed through oxidized glutathione, glutathione peroxidase, manganese superoxide dismutase, aconitase activities, and mitochondrial respiration. RESULTS Hypothalamic hypersensitivity to glucose was characterized by enhanced electrical activity of the arcuate nucleus and increased insulin secretion at a low glucose concentration, which does not produce such an effect in normal rats. It was associated with 1) increased reactive oxygen species levels in response to this low glucose load, 2) constitutive oxidized environment coupled with lower antioxidant enzyme activity at both the cellular and mitochondrial level, and 3) overexpression of several mitochondrial subunits of the respiratory chain coupled with a global dysfunction in mitochondrial activity. Moreover, pharmacological restoration of the glutathione hypothalamic redox state by reduced glutathione infusion in the third ventricle fully reversed the cerebral hypersensitivity to glucose. CONCLUSIONS The data demonstrated that obese Zücker rats' impaired hypothalamic regulation in terms of glucose sensing is linked to an abnormal redox signaling, which originates from mitochondria dysfunction. PMID:19581415

  10. Structural basis for leucine sensing by the Sestrin2-mTORC1 pathway

    DOE PAGES

    Saxton, Robert A.; Knockenhauer, Kevin E.; Wolfson, Rachel L.; ...

    2015-11-19

    Eukaryotic cells coordinate growth with the availability of nutrients through mTOR complex 1 (mTORC1), a master growth regulator. Leucine is of particular importance and activates mTORC1 via the Rag GTPases and their regulators GATOR1 and GATOR2. Sestrin2 interacts with GATOR2 and is a leucine sensor. We present the 2.7-Å crystal structure of Sestrin2 in complex with leucine. Leucine binds through a single pocket that coordinates its charged functional groups and confers specificity for the hydrophobic side chain. A loop encloses leucine and forms a lid-latch mechanism required for binding. A structure-guided mutation in Sestrin2 that decreases its affinity for leucinemore » leads to a concomitant increase in the leucine concentration required for mTORC1 activation in cells. Lastly, these results provide a structural mechanism of amino acid sensing by the mTORC1 pathway.« less

  11. Hypoxia-inducible factor directs POMC gene to mediate hypothalamic glucose sensing and energy balance regulation.

    PubMed

    Zhang, Hai; Zhang, Guo; Gonzalez, Frank J; Park, Sung-Min; Cai, Dongsheng

    2011-07-01

    Hypoxia-inducible factor (HIF) is a nuclear transcription factor that responds to environmental and pathological hypoxia to induce metabolic adaptation, vascular growth, and cell survival. Here we found that HIF subunits and HIF2α in particular were normally expressed in the mediobasal hypothalamus of mice. Hypothalamic HIF was up-regulated by glucose to mediate the feeding control of hypothalamic glucose sensing. Two underlying molecular pathways were identified, including suppression of PHDs by glucose metabolites to prevent HIF2α degradation and the recruitment of AMPK and mTOR/S6K to regulate HIF2α protein synthesis. HIF activation was found to directly control the transcription of POMC gene. Genetic approach was then employed to develop conditional knockout mice with HIF inhibition in POMC neurons, revealing that HIF loss-of-function in POMC neurons impaired hypothalamic glucose sensing and caused energy imbalance to promote obesity development. The metabolic effects of HIF in hypothalamic POMC neurons were independent of leptin signaling or pituitary ACTH pathway. Hypothalamic gene delivery of HIF counteracted overeating and obesity under conditions of nutritional excess. In conclusion, HIF controls hypothalamic POMC gene to direct the central nutrient sensing in regulation of energy and body weight balance.

  12. Nutrient-sensing hypothalamic TXNIP links nutrient excess to energy imbalance in mice.

    PubMed

    Blouet, Clémence; Schwartz, Gary J

    2011-04-20

    Nutrient excess in obesity and diabetes is emerging as a common putative cause for multiple deleterious effects across diverse cell types, responsible for a variety of metabolic dysfunctions. The hypothalamus is acknowledged as an important regulator of whole-body energy homeostasis, through both detection of nutrient availability and coordination of effectors that determine nutrient intake and utilization, thus preventing cellular and whole-body nutrient excess. However, the mechanisms underlying hypothalamic nutrient detection and its impact on peripheral nutrient utilization remain poorly understood. Recent data suggest a role for thioredoxin-interacting protein (TXNIP) as a molecular nutrient sensor important in the regulation of energy metabolism, but the role of hypothalamic TXNIP in the regulation of energy balance has not been evaluated. Here we show in mice that TXNIP is expressed in nutrient-sensing neurons of the mediobasal hypothalamus, responds to hormonal and nutrient signals, and regulates adipose tissue metabolism, fuel partitioning, and glucose homeostasis. Hypothalamic expression of TXNIP is induced by acute nutrient excess and in mouse models of obesity and diabetes, and downregulation of mediobasal hypothalamic TXNIP expression prevents diet-induced obesity and insulin resistance. Thus, mediobasal hypothalamic TXNIP plays a critical role in nutrient sensing and the regulation of fuel utilization.

  13. Hypothalamic glucose-sensing: role of Glia-to-neuron signaling.

    PubMed

    Tonon, M C; Lanfray, D; Castel, H; Vaudry, H; Morin, F

    2013-12-01

    The hypothalamus senses hormones and nutrients in order to regulate energy balance. In particular, detection of hypothalamic glucose levels has been shown to regulate both feeding behavior and peripheral glucose homeostasis, and impairment of this regulatory system is believed to be involved in the development of obesity and diabetes. Several data clearly demonstrate that glial cells are key elements in the perception of glucose, constituting with neurons a "glucose-sensing unit". Characterization of this interplay between glia and neurons represents an exciting challenge, and will undoubtedly contribute to identify new candidates for therapeutic intervention. The purpose of this review is to summarize the current data that stress the importance of glia in central glucose-sensing. The nature of the glia-to-neuron signaling is discussed, with a special focus on the endozepine ODN, a potent anorexigenic peptide that is highly expressed in hypothalamic glia.

  14. Hypothalamic astroglial connexins are required for brain glucose sensing-induced insulin secretion.

    PubMed

    Allard, Camille; Carneiro, Lionel; Grall, Sylvie; Cline, Brandon H; Fioramonti, Xavier; Chrétien, Chloé; Baba-Aissa, Fawzia; Giaume, Christian; Pénicaud, Luc; Leloup, Corinne

    2014-02-01

    Hypothalamic glucose detection participates in maintaining glycemic balance, food intake, and thermogenesis. Although hypothalamic neurons are the executive cells involved in these responses, there is increasing evidence that astrocytes participate in glucose sensing (GS); however, it is unknown whether astroglial networking is required for glucose sensitivity. Astroglial connexins 30 and 43 (Cx30 and Cx43) form hexameric channels, which are apposed in gap junctions, allowing for the intercellular transfer of small molecules such as glucose throughout the astroglial networks. Here, we hypothesized that hypothalamic glucose sensitivity requires these connexins. First, we showed that both Cxs are enriched in the rat hypothalamus, with highly concentrated Cx43 expression around blood vessels of the mediobasal hypothalamus (MBH). Both fasting and high glycemic levels rapidly altered the protein levels of MBH astroglial connexins, suggesting cross talk within the MBH between glycemic status and the connexins' ability to dispatch glucose. Finally, the inhibition of MBH Cx43 (by transient RNA interference) attenuated hypothalamic glucose sensitivity in rats, which was demonstrated by a pronounced decreased insulin secretion in response to a brain glucose challenge. These results illustrate that astroglial connexins contribute to hypothalamic GS.

  15. The effect of diet interventions on hypothalamic nutrient sensing pathways in rodents.

    PubMed

    Rijnsburger, Merel; Belegri, Evita; Eggels, Leslie; Unmehopa, Unga A; Boelen, Anita; Serlie, Mireille J; la Fleur, Susanne E

    2016-08-01

    The hypothalamus plays a fundamental role in regulating homeostatic processes including regulation of food intake. Food intake is driven in part by energy balance, which is sensed by specific brain structures through signaling molecules such as nutrients and hormones. Both circulating glucose and fatty acids decrease food intake via a central mechanism involving the hypothalamus and brain stem. Besides playing a role in signaling energy status, glucose and fatty acids serve as fuel for neurons. This review focuses on the effects of glucose and fatty acids on hypothalamic pathways involved in regulation of energy metabolism as well as on the role of the family of peroxisome proliferator activated receptors (PPARs) which are implicated in regulation of central energy homeostasis. We further discuss the effects of different hypercaloric diets on these pathways.

  16. Cell type-specific transcriptomics of hypothalamic energy-sensing neuron responses to weight-loss.

    PubMed

    Henry, Fredrick E; Sugino, Ken; Tozer, Adam; Branco, Tiago; Sternson, Scott M

    2015-09-02

    Molecular and cellular processes in neurons are critical for sensing and responding to energy deficit states, such as during weight-loss. Agouti related protein (AGRP)-expressing neurons are a key hypothalamic population that is activated during energy deficit and increases appetite and weight-gain. Cell type-specific transcriptomics can be used to identify pathways that counteract weight-loss, and here we report high-quality gene expression profiles of AGRP neurons from well-fed and food-deprived young adult mice. For comparison, we also analyzed Proopiomelanocortin (POMC)-expressing neurons, an intermingled population that suppresses appetite and body weight. We find that AGRP neurons are considerably more sensitive to energy deficit than POMC neurons. Furthermore, we identify cell type-specific pathways involving endoplasmic reticulum-stress, circadian signaling, ion channels, neuropeptides, and receptors. Combined with methods to validate and manipulate these pathways, this resource greatly expands molecular insight into neuronal regulation of body weight, and may be useful for devising therapeutic strategies for obesity and eating disorders.

  17. Cell type-specific transcriptomics of hypothalamic energy-sensing neuron responses to weight-loss

    PubMed Central

    Henry, Fredrick E; Sugino, Ken; Tozer, Adam; Branco, Tiago; Sternson, Scott M

    2015-01-01

    Molecular and cellular processes in neurons are critical for sensing and responding to energy deficit states, such as during weight-loss. Agouti related protein (AGRP)-expressing neurons are a key hypothalamic population that is activated during energy deficit and increases appetite and weight-gain. Cell type-specific transcriptomics can be used to identify pathways that counteract weight-loss, and here we report high-quality gene expression profiles of AGRP neurons from well-fed and food-deprived young adult mice. For comparison, we also analyzed Proopiomelanocortin (POMC)-expressing neurons, an intermingled population that suppresses appetite and body weight. We find that AGRP neurons are considerably more sensitive to energy deficit than POMC neurons. Furthermore, we identify cell type-specific pathways involving endoplasmic reticulum-stress, circadian signaling, ion channels, neuropeptides, and receptors. Combined with methods to validate and manipulate these pathways, this resource greatly expands molecular insight into neuronal regulation of body weight, and may be useful for devising therapeutic strategies for obesity and eating disorders. DOI: http://dx.doi.org/10.7554/eLife.09800.001 PMID:26329458

  18. Chronic exposure to KATP channel openers results in attenuated glucose sensing in hypothalamic GT1-7 neurons.

    PubMed

    Haythorne, Elizabeth; Hamilton, D Lee; Findlay, John A; Beall, Craig; McCrimmon, Rory J; Ashford, Michael L J

    2016-12-01

    Individuals with Type 1 diabetes (T1D) are often exposed to recurrent episodes of hypoglycaemia. This reduces hormonal and behavioural responses that normally counteract low glucose in order to maintain glucose homeostasis, with altered responsiveness of glucose sensing hypothalamic neurons implicated. Although the molecular mechanisms are unknown, pharmacological studies implicate hypothalamic ATP-sensitive potassium channel (KATP) activity, with KATP openers (KCOs) amplifying, through cell hyperpolarization, the response to hypoglycaemia. Although initial findings, using acute hypothalamic KCO delivery, in rats were promising, chronic exposure to the KCO NN414 worsened the responses to subsequent hypoglycaemic challenge. To investigate this further we used GT1-7 cells to explore how NN414 affected glucose-sensing behaviour, the metabolic response of cells to hypoglycaemia and KATP activity. GT1-7 cells exposed to 3 or 24 h NN414 exhibited an attenuated hyperpolarization to subsequent hypoglycaemic challenge or NN414, which correlated with diminished KATP activity. The reduced sensitivity to hypoglycaemia was apparent 24 h after NN414 removal, even though intrinsic KATP activity recovered. The NN414-modified glucose responsiveness was not associated with adaptations in glucose uptake, metabolism or oxidation. KATP inactivation by NN414 was prevented by the concurrent presence of tolbutamide, which maintains KATP closure. Single channel recordings indicate that NN414 alters KATP intrinsic gating inducing a stable closed or inactivated state. These data indicate that exposure of hypothalamic glucose sensing cells to chronic NN414 drives a sustained conformational change to KATP, probably by binding to SUR1, that results in loss of channel sensitivity to intrinsic metabolic factors such as MgADP and small molecule agonists.

  19. Effect of very high dose D-leucine6-gonadotropin-releasing hormone proethylamide on the hypothalamic-pituitary testicular axis in patients with prostatic cancer.

    PubMed Central

    Warner, B; Worgul, T J; Drago, J; Demers, L; Dufau, M; Max, D; Santen, R J

    1983-01-01

    Potent synthetic analogs of gonadotropin-releasing hormone produce parodoxical antireproductive effects when administered chronically. These compounds are minimally toxic and may exhibit no plateau of the dose-response curve even at very high doses. These considerations served as the basis for our systematic evaluation of [D-leucine6-desarginine-glycine-NH2(10)]gonadotropin-releasing hormone (GnRH-A) proethylamide in the very high dose range (i.e., 10-fold larger amounts than previously used). In rats given the analog for 12 wk, prostate, testis, and seminal vesicle weights were suppressed to a greater extent with 200 micrograms q.d. than with 40 micrograms q.d. (P less than 0.01 prostate, less than 0.01 testis, less than 0.01 seminal vesicles), indicating dose-response effects in the very high dose range. 200 micrograms of [D-Leu6-des-Gly-NH2(10]-GnRH-A consistently suppressed leutinizing hormone (LH) values at 6 and 12 wk (basal 71 +/- 9.5; 6 wk 34 +/- 3.8; 12 wk 28 +/- 5 ng/ml) whereas 40 micrograms suppressed LH variably (basal 33 +/- 3.8; 6 wk 17 +/- 3.9; 12 wk 32 +/- 5.2). Testosterone fell to 15 +/- 2.4 and 19 +/- 2.0 ng/100 ml in response to 200 micrograms q.d. and to 27 +/- 6.4 and 22 +/- 7.4 ng/100 ml with the 40-micrograms dose. These findings in the rodent prompted treatment of stage D prostate cancer patients with similarly high doses of [D-Leu6-des-Gly-NH2(10)]-GnRH-A. After treatment for 11 wk with 1,000 or 10,000 micrograms/d of the analog, testosterone and dihydrotestosterone levels transiently rose and then fell into the surgically castrate range (testosterone 19 +/- 4.4 ng/100 ml [D-Leu6-des-Gly-NH2(10)]-GnRH-A vs. surgically castrate 11 +/- 0.9 ng/100 ml, P = NS; dihydrotestosterone 15 +/- 1.7 ng/100 ml GnRH-A vs. surgically castrate 15 +/- 4.1 ng/100 ml. P = NS). However, unlike the chronic stimulatory effect on the pituitary at lower doses, very high dose therapy resulted in profound suppression of plasma and urine LH. Plasma levels fell to

  20. Hypothalamic sensing of ketone bodies after prolonged cerebral exposure leads to metabolic control dysregulation

    PubMed Central

    Carneiro, Lionel; Geller, Sarah; Hébert, Audrey; Repond, Cendrine; Fioramonti, Xavier; Leloup, Corinne; Pellerin, Luc

    2016-01-01

    Ketone bodies have been shown to transiently stimulate food intake and modify energy homeostasis regulatory systems following cerebral infusion for a moderate period of time (<6 hours). As ketone bodies are usually enhanced during episodes of fasting, this effect might correspond to a physiological regulation. In contrast, ketone bodies levels remain elevated for prolonged periods during obesity, and thus could play an important role in the development of this pathology. In order to understand this transition, ketone bodies were infused through a catheter inserted in the carotid to directly stimulate the brain for a period of 24 hours. Food ingested and blood circulating parameters involved in metabolic control as well as glucose homeostasis were determined. Results show that ketone bodies infusion for 24 hours increased food intake associated with a stimulation of hypothalamic orexigenic neuropeptides. Moreover, insulinemia was increased and caused a decrease in glucose production despite an increased resistance to insulin. The present study confirms that ketone bodies reaching the brain stimulates food intake. Moreover, we provide evidence that a prolonged hyperketonemia leads to a dysregulation of energy homeostasis control mechanisms. Finally, this study shows that brain exposure to ketone bodies alters insulin signaling and consequently glucose homeostasis. PMID:27708432

  1. Glucose sensing mechanisms in hypothalamic cell models: glucose inhibition of AgRP synthesis and secretion.

    PubMed

    Chalmers, Jennifer A; Jang, Janet J; Belsham, Denise D

    2014-01-25

    Glucose-sensing neurons play a role in energy homeostasis, yet how orexigenic neurons sense glucose remains unclear. As models of glucose-inhibited (GI) neurons, mHypoE-29/1 and mHypoA-NPY/GFP cells express the essential orexigenic neuropeptide AgRP and glucose sensing machinery. Exposure to increasing concentrations of glucose or the glucose analog 2-deoxyglucose (2-DG) results in a decrease in AgRP mRNA levels. Taste receptor, Tas1R2 mRNA expression was reduced by glucose, whereas 2-DG reduced Tas1R3 mRNA levels. Increasing glucose concentrations elicited a rise in Akt and neuronal nitric oxide synthase (nNOS) phosphorylation, CaMKKβ levels, and a reduction of AMP-kinase alpha phosphorylation. Inhibitors of NOS and the cystic fibrosis transmembrane conductance regulator (CFTR) prevented a decrease in AgRP secretion with glucose, suggesting a pivotal role for nNOS and the CFTR in glucose-sensing. These models possess the hallmark characteristics of GI neurons, and can be used to disentangle the mechanisms by which orexigenic neurons sense glucose.

  2. Hypothalamic mechanisms linking fatty acid sensing and food intake regulation in rainbow trout.

    PubMed

    Velasco, Cristina; Otero-Rodiño, Cristina; Comesana, Sara; Míguez, Jesús M; Soengas, Jose L

    2017-09-26

    We assessed in rainbow trout hypothalamus the effects of oleate and octanoate on levels and phosphorylation status of two transcription factors, FoxO1 and CREB, possibly involved in linking activation of fatty acid sensing with modulation of food intake through expression of brain neuropeptides. Moreover, we assessed changes in phosphorylation status of three proteins possibly involved in modulation of these transcription factors such as Akt, AMPK, and mTOR. In a first experiment, we evaluated in pools of hypothalamus incubated for 3h and 6h at 15 °C in modified Hanks' medium containing 100 or 500 µM oleate or octanoate, the response of fatty acid sensing, neuropeptide expression, and phosphorylation status of proteins of interest. The activation of fatty acid sensing and enhanced anorectic potential occurred in parallel with activation of Akt and mTOR, and inhibition of AMPK. The changes in these proteins would relate to neuropeptide expression through changes in phosphorylation status of transcription factors under their control, such as CREB and FoxO1, which displayed inhibitory (CREB) or activatory (FoxO1) responses when tissues were incubated with oleate or octanoate. In a second experiment, we incubated hypothalamus for 6h with 500 µM oleate or octanoate alone or in the presence of specific inhibitors of Akt, AMPK, mTOR, CREB or FoxO1. The presence of inhibitors counteracted the effects of oleate or octanoate on phosphorylation status of the proteins of interest. The results support, for the first time in fish, the involvement of these proteins in the regulation of food intake by fatty acids.

  3. Regulation of hypothalamic neuronal sensing and food intake by ketone bodies and fatty acids.

    PubMed

    Le Foll, Christelle; Dunn-Meynell, Ambrose A; Miziorko, Henri M; Levin, Barry E

    2014-04-01

    Metabolic sensing neurons in the ventromedial hypothalamus (VMH) alter their activity when ambient levels of metabolic substrates, such as glucose and fatty acids (FA), change. To assess the relationship between a high-fat diet (HFD; 60%) intake on feeding and serum and VMH FA levels, rats were trained to eat a low-fat diet (LFD; 13.5%) or an HFD in 3 h/day and were monitored with VMH FA microdialysis. Despite having higher serum levels, HFD rats had lower VMH FA levels but ate less from 3 to 6 h of refeeding than did LFD rats. However, VMH β-hydroxybutyrate (β-OHB) and VMH-to-serum β-OHB ratio levels were higher in HFD rats during the first 1 h of refeeding, suggesting that VMH astrocyte ketone production mediated their reduced intake. In fact, using calcium imaging in dissociated VMH neurons showed that ketone bodies overrode normal FA sensing, primarily by exciting neurons that were activated or inhibited by oleic acid. Importantly, bilateral inhibition of VMH ketone production with a 3-hydroxy-3-methylglutaryl-CoA synthase inhibitor reversed the 3- to 6-h HFD-induced inhibition of intake but had no effect in LFD-fed rats. These data suggest that a restricted HFD intake regimen inhibits caloric intake as a consequence of FA-induced VMH ketone body production by astrocytes.

  4. Nutrient sensing and insulin signaling in neuropeptide-expressing immortalized, hypothalamic neurons: A cellular model of insulin resistance.

    PubMed

    Fick, Laura J; Belsham, Denise D

    2010-08-15

    Obesity and type 2 diabetes mellitus represent a significant global health crisis. These two interrelated diseases are typified by perturbed insulin signaling in the hypothalamus. Using novel hypothalamic cell lines, we have begun to elucidate the molecular and intracellular mechanisms involved in the hypothalamic control of energy homeostasis and insulin resistance. In this review, we present evidence of insulin and glucose signaling pathways that lead to changes in neuropeptide gene expression. We have identified some of the molecular mechanisms involved in the control of de novo hypothalamic insulin mRNA expression. And finally, we have defined key mechanisms involved in the etiology of cellular insulin resistance in hypothalamic neurons that may play a fundamental role in cases of high levels of insulin or saturated fatty acids, often linked to the exacerbation of obesity and diabetes.

  5. The Arabidopsis leucine-rich repeat receptor kinase MIK2/LRR-KISS connects cell wall integrity sensing, root growth and response to abiotic and biotic stresses.

    PubMed

    Van der Does, Dieuwertje; Boutrot, Freddy; Engelsdorf, Timo; Rhodes, Jack; McKenna, Joseph F; Vernhettes, Samantha; Koevoets, Iko; Tintor, Nico; Veerabagu, Manikandan; Miedes, Eva; Segonzac, Cécile; Roux, Milena; Breda, Alice S; Hardtke, Christian S; Molina, Antonio; Rep, Martijn; Testerink, Christa; Mouille, Grégory; Höfte, Herman; Hamann, Thorsten; Zipfel, Cyril

    2017-06-01

    Plants actively perceive and respond to perturbations in their cell walls which arise during growth, biotic and abiotic stresses. However, few components involved in plant cell wall integrity sensing have been described to date. Using a reverse-genetic approach, we identified the Arabidopsis thaliana leucine-rich repeat receptor kinase MIK2 as an important regulator of cell wall damage responses triggered upon cellulose biosynthesis inhibition. Indeed, loss-of-function mik2 alleles are strongly affected in immune marker gene expression, jasmonic acid production and lignin deposition. MIK2 has both overlapping and distinct functions with THE1, a malectin-like receptor kinase previously proposed as cell wall integrity sensor. In addition, mik2 mutant plants exhibit enhanced leftward root skewing when grown on vertical plates. Notably, natural variation in MIK2 (also named LRR-KISS) has been correlated recently to mild salt stress tolerance, which we could confirm using our insertional alleles. Strikingly, both the increased root skewing and salt stress sensitivity phenotypes observed in the mik2 mutant are dependent on THE1. Finally, we found that MIK2 is required for resistance to the fungal root pathogen Fusarium oxysporum. Together, our data identify MIK2 as a novel component in cell wall integrity sensing and suggest that MIK2 is a nexus linking cell wall integrity sensing to growth and environmental cues.

  6. Hypothalamic fatty acid sensing in Senegalese sole (Solea senegalensis): response to long-chain saturated, monounsaturated, and polyunsaturated (n-3) fatty acids.

    PubMed

    Conde-Sieira, Marta; Bonacic, Kruno; Velasco, Cristina; Valente, Luisa M P; Morais, Sofia; Soengas, José L

    2015-12-15

    We assessed the presence of fatty acid (FA)-sensing mechanisms in hypothalamus of Senegalese sole (Solea senegalensis) and investigated their sensitivity to FA chain length and/or level of unsaturation. Stearate (SA, saturated FA), oleate (OA, monounsaturated FA of the same chain length), α-linolenate [ALA, a n-3 polyunsaturated fatty acid (PUFA) of the same chain length], and eicosapentanoate (EPA, a n-3 PUFA of a larger chain length) were injected intraperitoneally. Parameters related to FA sensing and neuropeptide expression in the hypothalamus were assessed after 3 h and changes in accumulated food intake after 4, 24, and 48 h. Three FA sensing systems characterized in rainbow trout were also found in Senegalese sole and were activated by OA in a way similar to that previously characterized in rainbow trout and mammals. These hypothalamic FA sensing systems were also activated by ALA, differing from mammals, where n-3 PUFAs do not seem to activate FA sensors. This might suggest additional roles and highlights the importance of n-3 PUFA in fish diets, especially in marine species. The activation of FA sensing seems to be partially dependent on acyl chain length and degree of saturation, as no major changes were observed after treating fish with SA or EPA. The activation of FA sensing systems by OA and ALA, but not SA or EPA, is further reflected in the expression of hypothalamic neuropeptides involved in the control of food intake. Both OA and ALA enhanced anorexigenic capacity compatible with the activation of FA sensing systems.

  7. A Fall in plasma free fatty acid (FFA) level activates the hypothalamic-pituitary-adrenal axis independent of plasma glucose: evidence for brain sensing of circulating FFA.

    PubMed

    Oh, Young Taek; Oh, Ki-Sook; Kang, Insug; Youn, Jang H

    2012-08-01

    The brain responds to a fall in blood glucose by activating neuroendocrine mechanisms for its restoration. It is unclear whether the brain also responds to a fall in plasma free fatty acids (FFA) to activate mechanisms for its restoration. We examined whether lowering plasma FFA increases plasma corticosterone or catecholamine levels and, if so, whether the brain is involved in these responses. Plasma FFA levels were lowered in rats with three independent antilipolytic agents: nicotinic acid (NA), insulin, and the A1 adenosine receptor agonist SDZ WAG 994 with plasma glucose clamped at basal levels. Lowering plasma FFA with these agents all increased plasma corticosterone, but not catecholamine, within 1 h, accompanied by increases in plasma ACTH. These increases in ACTH or corticosterone were abolished when falls in plasma FFA were prevented by Intralipid during NA or insulin infusion. In addition, the NA-induced increases in plasma ACTH were completely prevented by administration of SSR149415, an arginine vasopressin receptor antagonist, demonstrating that the hypothalamus is involved in these responses. Taken together, the present data suggest that the brain may sense a fall in plasma FFA levels and activate the hypothalamic-pituitary-adrenal axis to increase plasma ACTH and corticosterone, which would help restore FFA levels. Thus, the brain may be involved in the sensing and control of circulating FFA levels.

  8. Leucine aminopeptidase - urine

    MedlinePlus

    ... GO About MedlinePlus Site Map FAQs Customer Support Health Topics Drugs & Supplements Videos & Tools Español You Are Here: Home → Medical Encyclopedia → Leucine aminopeptidase - urine URL of this page: //medlineplus.gov/ ...

  9. Leucine aminopeptidase urine test (image)

    MedlinePlus

    Leucine aminopeptidase (LAP) is a proteolytic enzyme that breaks chemical bonds in proteins at specific sites next to leucine amino acids. Serum (blood) LAP is measured to diagnose liver (hepatic) dysfunction.

  10. The basic leucine zipper stress response regulator Yap5 senses high-iron conditions by coordination of [2Fe-2S] clusters.

    PubMed

    Rietzschel, Nicole; Pierik, Antonio J; Bill, Eckhard; Lill, Roland; Mühlenhoff, Ulrich

    2015-01-01

    Iron is an essential, yet at elevated concentrations toxic trace element. To date, the mechanisms of iron sensing by eukaryotic iron-responsive transcription factors are poorly understood. The Saccharomyces cerevisiae transcription factor Yap5, a member of the Yap family of bZIP stress response regulators, administrates the adaptive response to high-iron conditions. Despite the central role of the iron-sensing process for cell viability, the molecule perceived by Yap5 and the underlying regulatory mechanisms are unknown. Here, we show that Yap5 senses high-iron conditions by two Fe/S clusters bound to its activator domain (Yap5-AD). The more stable iron-regulatory Fe/S cluster at the N-terminal cysteine-rich domain (n-CRD) of Yap5 is detected in vivo and in vitro. The second cluster coordinated by the C-terminal CRD can only be shown after chemical reconstitution, since it is bound in a labile fashion. Both clusters are of the [2Fe-2S] type as characterized by UV/visible (UV/Vis), circular dichroism, electron paramagnetic resonance (EPR), and Mössbauer spectroscopy. Fe/S cluster binding to Yap5-AD induces a conformational change that may activate transcription. The cluster-binding motif of the n-CRD domain is highly conserved in HapX-like transcription factors of pathogenic fungi and thus may represent a general sensor module common to many eukaryotic stress response regulators.

  11. The Basic Leucine Zipper Stress Response Regulator Yap5 Senses High-Iron Conditions by Coordination of [2Fe-2S] Clusters

    PubMed Central

    Rietzschel, Nicole; Pierik, Antonio J.; Bill, Eckhard; Mühlenhoff, Ulrich

    2014-01-01

    Iron is an essential, yet at elevated concentrations toxic trace element. To date, the mechanisms of iron sensing by eukaryotic iron-responsive transcription factors are poorly understood. The Saccharomyces cerevisiae transcription factor Yap5, a member of the Yap family of bZIP stress response regulators, administrates the adaptive response to high-iron conditions. Despite the central role of the iron-sensing process for cell viability, the molecule perceived by Yap5 and the underlying regulatory mechanisms are unknown. Here, we show that Yap5 senses high-iron conditions by two Fe/S clusters bound to its activator domain (Yap5-AD). The more stable iron-regulatory Fe/S cluster at the N-terminal cysteine-rich domain (n-CRD) of Yap5 is detected in vivo and in vitro. The second cluster coordinated by the C-terminal CRD can only be shown after chemical reconstitution, since it is bound in a labile fashion. Both clusters are of the [2Fe-2S] type as characterized by UV/visible (UV/Vis), circular dichroism, electron paramagnetic resonance (EPR), and Mössbauer spectroscopy. Fe/S cluster binding to Yap5-AD induces a conformational change that may activate transcription. The cluster-binding motif of the n-CRD domain is highly conserved in HapX-like transcription factors of pathogenic fungi and thus may represent a general sensor module common to many eukaryotic stress response regulators. PMID:25368382

  12. Leucine as a treatment for muscle wasting: a critical review.

    PubMed

    Ham, Daniel J; Caldow, Marissa K; Lynch, Gordon S; Koopman, René

    2014-12-01

    Amino acids are potent modulators of protein turnover and skeletal muscle cells are highly sensitive to changes in amino acid availability. During amino acid abundance increased activity of mTORC1 drives protein synthesis and growth. In skeletal muscle, it has been clearly demonstrated that of all the amino acids, leucine is the most potent stimulator of mTORC1 and protein synthesis in vitro and in vivo. As such, leucine has received considerable attention as a potential pharmaconutrient for the treatment of numerous muscle wasting conditions. However, despite a multitude of studies showing enhanced acute protein synthesis with leucine or leucine-rich supplements in healthy individuals, additional leucine intake does not necessarily enhance protein synthesis during muscle wasting conditions. In addition, long-term, placebo controlled, iso-caloric studies in humans consistently show no beneficial effect of leucine supplementation on skeletal muscle mass or function. This review, critically evaluates the therapeutic potential of leucine to attenuate the skeletal muscle wasting associated with ageing, cancer and immobilization/bed rest. It also highlights the impact of inflammation on amino acid sensing, mTORC1 activation and stimulation of protein synthesis and challenges the underlying hypothesis that the acute activation of mTORC1 and stimulation of protein synthesis by leucine increases in muscle mass over time. We conclude that leucine, as a standalone nutritional intervention, is not effective in the prevention of muscle wasting. Future work should focus on identifying and utilizing other nutrients or treatments that sensitize skeletal muscle to leucine, thereby enhancing its therapeutic potential for muscle wasting conditions.

  13. Leucine metabolism in human newborns

    SciTech Connect

    Denne, S.C.; Kalhan, S.C. )

    1987-12-01

    The present study was designed to (1) determine whether a relationship exists between newborn birth weight and leucine metabolism and (2) compare leucine and energy metabolism in a period of rapid growth and development (i.e., newborn) with a constant nongrowth period (i.e., adult). Leucine kinetics and energy expenditure were measured in the postabsorptive state in 12 normal full-term newborns in early neonatal life and in 11 normal adults using a primed constant L-(1-{sup 13}C)leucine infusion combined with respiratory calorimetry. A significant positive correlation between newborn birth weight and leucine flux was observed. These data suggest the following. (1) A relationship exists between newborn birth weight and protein metabolism, as reflected by the correlation between leucine flux when expressed as micromoles per kilogram per hour and birth weight. (2) The high rate of leucine flux measured in newborns probably reflects the rapid remodeling of protein that occurs in this period of development, even during fasting. (3) The similar values in newborns and adults of leucine kinetics and energy expenditure when normalized to metabolic body weight and the nearly equivalent allometric exponents relating body weight to leucine flux and energy expenditure support a close relationship between leucine and energy metabolism, at least at the extremes of human growth.

  14. Hypothalamic AMP-Activated Protein Kinase Regulates Glucose Production

    PubMed Central

    Yang, Clair S.; Lam, Carol K.L.; Chari, Madhu; Cheung, Grace W.C.; Kokorovic, Andrea; Gao, Sun; Leclerc, Isabelle; Rutter, Guy A.; Lam, Tony K.T.

    2010-01-01

    OBJECTIVE The fuel sensor AMP-activated protein kinase (AMPK) in the hypothalamus regulates energy homeostasis by sensing nutritional and hormonal signals. However, the role of hypothalamic AMPK in glucose production regulation remains to be elucidated. We hypothesize that bidirectional changes in hypothalamic AMPK activity alter glucose production. RESEARCH DESIGN AND METHODS To introduce bidirectional changes in hypothalamic AMPK activity in vivo, we first knocked down hypothalamic AMPK activity in male Sprague-Dawley rats by either injecting an adenovirus expressing the dominant-negative form of AMPK (Ad-DN AMPKα2 [D157A]) or infusing AMPK inhibitor compound C directly into the mediobasal hypothalamus. Next, we independently activated hypothalamic AMPK by delivering either an adenovirus expressing the constitutive active form of AMPK (Ad-CA AMPKα1312 [T172D]) or the AMPK activator AICAR. The pancreatic (basal insulin)-euglycemic clamp technique in combination with the tracer-dilution methodology was used to assess the impact of alternations in hypothalamic AMPK activity on changes in glucose kinetics in vivo. RESULTS Injection of Ad-DN AMPK into the hypothalamus knocked down hypothalamic AMPK activity and led to a significant suppression of glucose production with no changes in peripheral glucose uptake during the clamps. In parallel, hypothalamic infusion of AMPK inhibitor compound C lowered glucose production as well. Conversely, molecular and pharmacological activation of hypothalamic AMPK negated the ability of hypothalamic nutrients to lower glucose production. CONCLUSIONS These data indicate that changes in hypothalamic AMPK activity are sufficient and necessary for hypothalamic nutrient-sensing mechanisms to alter glucose production in vivo. PMID:20682691

  15. Leptin Signaling Is Required for Leucine Deprivation-enhanced Energy Expenditure*

    PubMed Central

    Zhang, Qian; Liu, Bin; Cheng, Ying; Meng, Qingshu; Xia, Tingting; Jiang, Lei; Chen, Shanghai; Liu, Yong; Guo, Feifan

    2014-01-01

    Leptin signaling in the hypothalamus is crucial in energy homeostasis. We have previously shown that dietary deprivation of the essential amino acid leucine in mice stimulates fat loss by increasing energy expenditure. The involvement of leptin signaling in this regulation, however, has not been reported. Here, we show that leucine deprivation promotes leptin signaling in mice maintained on an otherwise normal diet and restores leptin responses in mice maintained on a high fat diet, a regimen known to induce leptin resistance. In addition, we found that leucine deprivation stimulated energy expenditure, and fat loss was largely blocked in db/db mice homozygous for a mutation in leptin receptor and a knock-in mouse line Y3F with abrogation of leptin receptor Tyr1138-mediated signal transducer and activator transcript 3 signaling. Overall, our studies describe a novel link between hypothalamic leptin signaling and stimulation of energy expenditure under leucine deprivation. PMID:24302741

  16. Visualization of Leucyl-tRNA synthetase in lysosome depending on leucine sensor.

    PubMed

    Choi, Hyosun; Son, Jung Bae; Kang, Jooyoun; Kwon, Jiwoong; Kim, Jong Hyun; Jung, Minkyo; Kim, Seong Keun; Kim, Sunghoon; Mun, Ji Young

    2017-09-04

    Leucyl-tRNA synthetase (LRS) plays major roles in providing leucine-tRNA and activating mechanistic target of rapamycin complex 1 (mTORC1) through intracellular leucine sensing. mTORC1 activated by amino acids affects the influence on physiology functions including cell proliferation, protein synthesis and autophagy in various organisms. Biochemical results demonstrating leucine sensing have been published, but visual results are lacking. Therefore, we observed the location of LRS with and without leucine using stimulated emission depletion (STED) microscopy one of the super-resolution microscopy and transmission electron microscopy (TEM). This revealed that LRS was translocated to the lysosome on addition of leucine. The translocation was inhibited by treatment with compound BC-LI-0186, disrupting the interaction between RagD and LRS. Immuno-TEM revealed a clear decrease in LRS translocation to the lysosome on addition of the inhibitor. This direct visualization of leucine sensing and LRS translocation to the lysosome was related to mTORC1 activation. To study the relationship between mTORC1 activation and LRS translocation, we monitored the change in autophagy for each condition using TEM and CLSM. The results showed a decrease in autophagy on addition of leucine, demonstrating crosstalk between leucine sensing, LRS translocation, RagD interaction, and mTORC1 activation. Copyright © 2017. Published by Elsevier Inc.

  17. The role of tanycytes in hypothalamic glucosensing

    PubMed Central

    Elizondo-Vega, Roberto; Cortes-Campos, Christian; Barahona, Maria J; Oyarce, Karina A; Carril, Claudio A; García-Robles, Maria A

    2015-01-01

    Tanycytes are elongated hypothalamic glial cells that cover the basal walls of the third ventricle; their apical regions contact the cerebrospinal fluid (CSF), and their processes reach hypothalamic neuronal nuclei that control the energy status of an organism. These nuclei maintain the balance between energy expenditure and intake, integrating several peripheral signals and triggering cellular responses that modify the feeding behaviour and peripheral glucose homeostasis. One of the most important and well-studied signals that control this process is glucose; however, the mechanism by which this molecule is sensed remains unknown. We along with others have proposed that tanycytes play a key role in this process, transducing changes in CSF glucose concentration to the neurons that control energy status. Recent studies have demonstrated the expression and function of monocarboxylate transporters and canonical pancreatic β cell glucose sensing molecules, including glucose transporter 2 and glucokinase, in tanycytes. These and other data, which will be discussed in this review, suggest that hypothalamic glucosensing is mediated through a metabolic interaction between tanycytes and neurons through lactate. This article will summarize the recent evidence that supports the importance of tanycytes in hypothalamic glucosensing, and discuss the possible mechanisms involved in this process. Finally, it is important to highlight that a detailed analysis of this mechanism could represent an opportunity to understand the evolution of associated pathologies, including diabetes and obesity, and identify new candidates for therapeutic intervention. PMID:26081217

  18. Hypothalamic obesity in children.

    PubMed

    Bereket, A; Kiess, W; Lustig, R H; Muller, H L; Goldstone, A P; Weiss, R; Yavuz, Y; Hochberg, Z

    2012-09-01

    Hypothalamic obesity is an intractable form of obesity syndrome that was initially described in patients with hypothalamic tumours and surgical damage. However, this definition is now expanded to include obesity developing after a variety of insults, including intracranial infections, infiltrations, trauma, vascular problems and hydrocephalus, in addition to acquired or congenital functional defects in central energy homeostasis in children with the so-called common obesity. The pathogenetic mechanisms underlying hypothalamic obesity are complex and multifactorial. Weight gain results from damage to the ventromedial hypothalamus, which leads, variously, to hyperphagia, a low-resting metabolic rate; autonomic imbalance; growth hormone-, gonadotropins and thyroid-stimulating hormone deficiency; hypomobility; and insomnia. Hypothalamic obesity did not receive enough attention, as evidenced by rarity of studies in this group of patients. A satellite symposium was held during the European Congress of Obesity in May 2011, in Istanbul, Turkey, to discuss recent developments and concepts regarding pathophysiology and management of hypothalamic obesity in children. An international group of leading researchers presented certain aspects of the problem. This paper summarizes the highlights of this symposium. Understanding the central role of the hypothalamus in the regulation of feeding and energy metabolism will help us gain insights into the pathogenesis and management of common obesity. © 2012 The Authors. obesity reviews © 2012 International Association for the Study of Obesity.

  19. Hypothalamic inflammation: a double-edged sword to nutritional diseases

    PubMed Central

    Cai, Dongsheng; Liu, Tiewen

    2015-01-01

    The hypothalamus is one of the master regulators of various physiological processes, including energy balance and nutrient metabolism. These regulatory functions are mediated by discrete hypothalamic regions that integrate metabolic sensing with neuroendocrine and neural controls of systemic physiology. Neurons and non-neuronal cells in these hypothalamic regions act supportively to execute metabolic regulations. Under conditions of brain and hypothalamic inflammation, which may result from overnutrition-induced intracellular stresses or disease-associated systemic inflammatory factors, extracellular and intracellular environments of hypothalamic cells are disrupted, leading to central metabolic dysregulations and various diseases. Recent research has begun to elucidate the effects of hypothalamic inflammation in causing diverse components of metabolic syndrome leading to diabetes and cardiovascular disease. These new understandings have provocatively expanded previous knowledge on the cachectic roles of brain inflammatory response in diseases, such as infections and cancers. This review describes the molecular and cellular characteristics of hypothalamic inflammation in metabolic syndrome and related diseases as opposed to cachectic diseases, and also discusses concepts and potential applications of inhibiting central/hypothalamic inflammation to treat nutritional diseases. PMID:22417140

  20. Leucine in Obesity: Therapeutic Prospects.

    PubMed

    Yao, Kang; Duan, Yehui; Li, Fengna; Tan, Bie; Hou, Yongqing; Wu, Guoyao; Yin, Yulong

    2016-08-01

    Obesity develops from an imbalance of energy homeostasis and is associated with chronic low-grade inflammation in white adipose tissues (WAT). Inflammation is involved in the pathophysiology of many obesity-induced disorders including insulin resistance and diabetes. Increasing evidence has shown that dietary leucine supplementation positively affects the parameters associated with obesity and obesity-related metabolic disorders. The beneficial effects include increased loss of body weight, reduced WAT inflammation, improved lipid and glucose metabolism, enhanced mitochondrial function, and preserved lean body mass. Although these beneficial effects have not been clearly established, dietary leucine supplementation, either alone or as part of a therapeutic regimen, may be a good nutritional tool in the prevention and management of obesity and obesity-induced metabolic disorders. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Regulation of Blood Glucose by Hypothalamic Pyruvate Metabolism

    NASA Astrophysics Data System (ADS)

    Lam, Tony K. T.; Gutierrez-Juarez, Roger; Pocai, Alessandro; Rossetti, Luciano

    2005-08-01

    The brain keenly depends on glucose for energy, and mammalians have redundant systems to control glucose production. An increase in circulating glucose inhibits glucose production in the liver, but this negative feedback is impaired in type 2 diabetes. Here we report that a primary increase in hypothalamic glucose levels lowers blood glucose through inhibition of glucose production in rats. The effect of glucose requires its conversion to lactate followed by stimulation of pyruvate metabolism, which leads to activation of adenosine triphosphate (ATP)-sensitive potassium channels. Thus, interventions designed to enhance the hypothalamic sensing of glucose may improve glucose homeostasis in diabetes.

  2. Leucine and tryptophan metabolism in rats.

    PubMed Central

    Salter, M; Bender, D A; Pogson, C I

    1985-01-01

    The rate of tryptophan metabolism in isolated liver cells from animals fed on a high-leucine diet was greater than for cells from control animals. Leucine inhibited tryptophan metabolism and tryptophan uptake in isolated liver cells, probably by competing for membrane transport. Leucine had no effect on tryptophan 2,3-dioxygenase in vitro. 4-Methyl-2-oxovalerate increased tryptophan oxidation in incubations containing albumin, by displacing bound tryptophan and increasing the availability of the amino acid to the cell. The results suggest that, under extreme conditions, when the availability of tryptophan is low, leucine may be pellagragenic. PMID:3977834

  3. Leucine metabolism in patients with Hepatic Encephalopathy

    SciTech Connect

    McGhee, A.S.; Kassouny, M.E.; Matthews, D.E.; Millikan, W.

    1986-03-01

    A primed continuous infusion of (/sup 15/N, 1-/sup 13/C)leucine was used to determine whether increased oxidation and/or protein synthesis of leucine occurs in patients with cirrhosis. Five controls and patients were equilibrated on a metabolic balance diet (0.6 g protein per kg ideal body weight (IBW)). An additional four patients were equilibrated in the same manner with the same type of diet with a protein level of 0.75 g per kg IBW. Plasma leucine and breath CO/sub 2/ enrichments were measured by mass spectrometry. Protein synthesis and leucine metabolism were identical in controls and patients when both were fed a diet with 0.6 g protein/kg IBW. Results indicate that systemic derangements of leucine metabolism are not the cause of Hepatic Encephalopathy.

  4. A Heterospecific Leucine Zipper Tetramer

    SciTech Connect

    Deng, Y.; Liu, J; Zheng, Q; Li, Q; Kallenbach, N; Lu, M

    2008-01-01

    Protein-protein interactions dictate the assembly of the macromolecular complexes essential for functional networks and cellular behavior. Elucidating principles of molecular recognition governing important interfaces such as coiled coils is a challenging goal for structural and systems biology. We report here that two valine-containing mutants of the GCN4 leucine zipper that fold individually as four-stranded coiled coils associate preferentially in mixtures to form an antiparallel, heterotetrameric structure. X-ray crystallographic analysis reveals that the coinciding hydrophobic interfaces of the hetero- and homotetramers differ in detail, explaining their partnering and structural specificity. Equilibrium disulfide exchange and thermal denaturation experiments show that the 50-fold preference for heterospecificity results from a combination of preferential packing and hydrophobicity. The extent of preference is sensitive to the side chains comprising the interface. Thus, heterotypic versus homotypic interaction specificity in coiled coils reflects a delicate balance in complementarity of shape and chemistry of the participating side chains.

  5. [Hypothalamic involvement in multiple sclerosis].

    PubMed

    Darlix, A; Mathey, G; Monin, M-L; Sauvée, M; Braun, M; Schaff, J-L; Debouverie, M

    2012-05-01

    Hypothalamic involvement is a rare condition in patients with multiple sclerosis (MS). We report two patients with a long history of MS who presented with severe acute hypothermia with associated thrombocytopenia and elevated transaminase levels. Several cases of hypothermia or hyperthermia in patients with MS have been reported in the literature. They could be linked with hypothalamic lesions, in particular in the pre-optic area. However, other anatomical locations seem to be involved in thermoregulation and can be affected by MS. Besides, some cases of syndrome of inappropriate antidiuretic hormone secretion have been reported in patients with MS. Finally, some sleep disorders, particularly hypersomnia or narcolepsy, could be related to hypothalamic lesions, through the fall in hypocretin-1 in the cerebrospinal fluid. Hypocretin-1 is a neuropeptide that is secreted by some hypothalamic cells. It plays a role in the sleep-awake rhythm. We report one patient with narcolepsy and cataplexy before the first symptoms of MS appeared. Hypothalamic signs are rare in MS. However, several series of autopsies have shown a high frequency of demyelinating lesions in the hypothalamic area. Among these lesions, the proportion of active lesions seems elevated. Yet only few of them have a clinical or biological translation such as thermoregulation dysfunction, sleep disorders or natremia abnormalities. Thus, it seems unlikely that inflammatory hypothalamic lesions alone, even when bilateral, could be the explanation of these signs. A sufficient number of inflammatory demyelinating lesions, which we can observe in patients with a long history of MS and an already severe disability, is probably necessary to develop such a rare symptomatology. Hypothalamic signs might be a factor of poor prognosis for the disease course and progression of the disability.

  6. Disturbances of the hypothalamic thermoregulation.

    PubMed

    Clar, H E

    1985-01-01

    Although compression of the hypothalamus in cases of suprasellar tumour is common, spontaneous dysregulation of body temperature is extremely rare. Bilateral localization of the hypothalamic nuclei and a high grade of compensatory value of temperature regulation may be the reason for this phenomenon. In the postoperative period temperature dysregulation is observed more often. In order to analyse the influence of diencephalic regulation in these patients classification of the degree of hypothalamic compression is necessary. The problem was studied under experimental and clinical conditions. Experimental studies in rabbits after acute hypothalamic compression and decompression showed a reversible disturbances of temperature regulation. Hypothalamic compression in dogs resulted in reversible hypothalamic endocrine dysfunction. Clinical observations of body temperature in the period after operation of suprasellar tumors showed similar results. The temperature study was extended on patients with cerebral trauma and intracranial haemorrhage to differentiate the degree of hypothalamic lesion. Morphological examinations confirmed alterations localized in the anterior and posterior region of the hypothalamus. The analysis proved the fact that temperature regulation seems to be a highly sensitive parameter of diencephalic function.

  7. [Functional hypothalamic amenorrhea].

    PubMed

    Stárka, Luboslav; Dušková, Michaela

    2015-10-01

    Functional hypothalamic amenorrhea (FHA) besides pregnancy and syndrome of polycystic ovary is one of the most common causes of secondary amenorrhea. FHA results from the aberrations in pulsatile gonadotropin-releasing hormone (GnRH) secretion, which in turn causes impairment of the gonadotropins (follicle-stimulating hormone and luteinizing hormone). FHA is a form of the defence of organism in situations where life functions are more important than reproductive function. FHA is reversible; it can be normalized after ceasing the stress situation. There are three types of FHA: weight loss related, stress-related, and exercise-related amenorrhea. The final consequences are complex hormonal changes manifested by profound hypoestrogenism. Additionally, these patients present mild hypercortisolemia, low serum insulin levels, low insulin-like growth factor 1 (IGF-1) and low total triiodothyronine. Women health in this disorder is disturbed in several aspects including the skeletal system, cardiovascular system, and mental problems. Patients manifest a decrease in bone mass density, which is related to an increase in fracture risk. Therefore, osteopenia and osteoporosis are the main long-term complications of FHA. Cardiovascular complications include endothelial dysfunction and abnormal changes in the lipid profile. FHA patients present significantly higher depression and anxiety and also sexual problems compared to healthy subjects.

  8. [Hypothalamic dysfunction in obesity].

    PubMed

    van de Sande-Lee, Simone; Velloso, Licio A

    2012-08-01

    Obesity, defined as abnormal or excessive fat accumulation that may impair life quality, is one of the major public health problems worldwide. It results from an imbalance between food intake and energy expenditure. The control of energy balance in animals and humans is performed by the central nervous system (CNS) by means of neuroendocrine connections, in which circulating peripheral hormones, such as leptin and insulin, provide signals to specialized neurons of the hypothalamus reflecting body fat stores, and induce appropriate responses to maintain the stability of these stores. The majority of obesity cases are associated with central resistance to both leptin and insulin actions. In experimental animals, high-fat diets can induce an inflammatory process in the hypothalamus, which impairs leptin and insulin intracellular signaling pathways, and results in hyperphagia, decreased energy expenditure and, ultimately, obesity. Recent evidence obtained from neuroimaging studies and assessment of inflammatory markers in the cerebrospinal fluid of obese subjects suggests that similar alterations may be also present in humans. In this review, we briefly present the mechanisms involved with the loss of homeostatic control of energy balance in animal models of obesity, and the current evidence of hypothalamic dysfunction in obese humans.

  9. Regulation of Leucine Catabolism in Pseudomonas putida

    PubMed Central

    Massey, Linda K.; Conrad, Robert S.; Sokatch, John R.

    1974-01-01

    The generation time of Pseudomonas putida with l-leucine was 20 h in synthetic media but only 3 h with d-leucine. Slow growth in the presence of l-leucine was partially overcome by addition of 0.1 mM amounts of either d-valine, l-valine, or 2-ketoisovalerate. The activities of five enzymes which take part in the oxidation of leucine by P. putida were measured under various conditions of growth. Four enzymes were induced by growth with dl-leucine as sole source of carbon: d-amino acid dehydrogenase, branched-chain keto acid dehydrogenase, 3-methylcrotonyl-coenzyme A carboxylase, and 3-hydroxy-3-methylglutaryl-coenzyme A lyase. The segment of the pathway required for oxidation of 3-methylcrotonate was induced by growth on isovalerate or 3-methylcrotonate without formation of the preceding enzymes. The synthesis of carboxylase and lyase appeared to have been repressed by the addition of l-glutamate or glucose to cells growing on dl-leucine as the sole carbon source. Mutants unable to grow at the expense of isovalerate had reduced levels of carboxylase and lyase, whereas the levels of three enzymes common to the catabolism of all three branched-chain amino acids and those of two isoleucine catabolic enzymes were normal. PMID:4150714

  10. Gelastic epilepsy: Beyond hypothalamic hamartomas.

    PubMed

    Uribe-San-Martin, Reinaldo; Ciampi, Ethel; Lawson-Peralta, Balduin; Acevedo-Gallinato, Keryma; Torrealba-Marchant, Gonzalo; Campos-Puebla, Manuel; Godoy-Fernández, Jaime

    2015-01-01

    Gelastic epilepsy or laughing seizures have been historically related to children with hypothalamic hamartomas. We report three adult patients who had gelastic epilepsy, defined as the presence of seizures with a prominent laugh component, including brain imaging, surface/invasive electroencephalography, positron emission tomography, and medical/surgical outcomes. None of the patients had hamartoma or other hypothalamic lesion. Two patients were classified as having refractory epilepsy (one had biopsy-proven neurocysticercosis and the other one hippocampal sclerosis and temporal cortical dysplasia). The third patient had no lesion on MRI and had complete control with carbamazepine. Both lesional patients underwent resective surgery, one with complete seizure control and the other one with poor outcome. Although hypothalamic hamartomas should always be ruled out in patients with gelastic epilepsy, laughing seizures can also arise from frontal and temporal lobe foci, which can be surgically removed. In addition, we present the first case of gelastic epilepsy due to neurocysticercosis.

  11. Dietary l-leucine supplementation of lactating rats results in a tendency to increase lean/fat ratio associated to lower orexigenic neuropeptide expression in hypothalamus.

    PubMed

    López, N; Sánchez, J; Picó, C; Palou, A; Serra, F

    2010-07-01

    The aim of this study was to assess the effects of dietary leucine supplementation in lactating dams, particularly on energy homeostasis through signaling mechanisms in the central nervous system. Dams were fed ad libitum with standard diet during pregnancy (control dams) or supplemented with 2% leucine (leucine-supplemented dams) from delivery onwards. Food intake, body weight and composition were periodically recorded. Hypothalamus was collected at the end of lactation, and the expression of neuropeptide Y (NPY), agouti-related protein (AgRP) pro-opiomelanocortin (POMC), cocaine and amphetamine regulated transcript (CART), insulin receptor (InsR), ghrelin receptor (GSHR), melanocortin receptor (MCR4), leptin receptor (Ob-Rb) and suppressor of cytokine signaling 3 (SOCS3) were analyzed. Dietary leucine supplementation to lactating rats increased plasma leucine by 56%, modulated body composition and contributed to a tendency of higher ratio of lean/fat mass content of dams during lactation, without affecting food intake, thermogenesis capacity or body or tissue/organs weights. No differences in body weight of offspring from control and leucine-supplemented dams were found. The expression of orexigenic peptides (NPY and AgRP) decreased in leucine-dams, whereas the expression of anorexigenic peptides (POMC and CART), the hypothalamic receptors of insulin, ghrelin, melanocortin and leptin and SOCS3 did not change by leucine supplementation. In conclusion, increased leucine intake during lactation may contribute to a healthier profile of body composition in dams, without compromising the growth and development of the progeny by a mechanism associated with lower expression of orexigenic neuropeptides in hypothalamus.

  12. Torsional nystagmus in hypothalamic hamartoma.

    PubMed

    Shaikh, Aasef G

    2013-12-01

    Torsional nystagmus was noted in a patient with hypothalamic hamartoma. Magnetic resonance imaging revealed an exophytic hypothalamic mass extending into the pre-pontine cistern and abutting ventral mesencephalon. The quickphase of the torsional nystagmus was directed towards the left side, ipsilateral to the side of compression by the hamartoma. Ipsi-lesionally directed pure torsional nystagmus in this case is attributed to the compressive lesion of ocular motor structures responsible for the neural integration of torsional and vertical eye movements, the interstitial nucleus of Cajal. [Published with video sequences].

  13. Hypothyroidism Compromises Hypothalamic Leptin Signaling in Mice

    PubMed Central

    Groba, Claudia; Mayerl, Steffen; van Mullem, Alies A.; Visser, Theo J.; Darras, Veerle M.; Habenicht, Andreas J.

    2013-01-01

    The impact of thyroid hormone (TH) on metabolism and energy expenditure is well established, but the role of TH in regulating nutritional sensing, particularly in the central nervous system, is only poorly defined. Here, we studied the consequences of hypothyroidism on leptin production as well as leptin sensing in congenital hypothyroid TRH receptor 1 knockout (Trhr1 ko) mice and euthyroid control animals. Hypothyroid mice exhibited decreased circulating leptin levels due to a decrease in fat mass and reduced leptin expression in white adipose tissue. In neurons of the hypothalamic arcuate nucleus, hypothyroid mice showed increased leptin receptor Ob-R expression and decreased suppressor of cytokine signaling 3 transcript levels. In order to monitor putative changes in central leptin sensing, we generated hypothyroid and leptin-deficient animals by crossing hypothyroid Trhr1 ko mice with the leptin-deficient ob/ob mice. Hypothyroid Trhr1/ob double knockout mice showed a blunted response to leptin treatment with respect to body weight and food intake and exhibited a decreased activation of phospho-signal transducer and activator of transcription 3 as well as a up-regulation of suppressor of cytokine signaling 3 upon leptin treatment, particularly in the arcuate nucleus. These data indicate alterations in the intracellular processing of the leptin signal under hypothyroid conditions and thereby unravel a novel mode of action by which TH affects energy metabolism. PMID:23518925

  14. Hypothyroidism compromises hypothalamic leptin signaling in mice.

    PubMed

    Groba, Claudia; Mayerl, Steffen; van Mullem, Alies A; Visser, Theo J; Darras, Veerle M; Habenicht, Andreas J; Heuer, Heike

    2013-04-01

    The impact of thyroid hormone (TH) on metabolism and energy expenditure is well established, but the role of TH in regulating nutritional sensing, particularly in the central nervous system, is only poorly defined. Here, we studied the consequences of hypothyroidism on leptin production as well as leptin sensing in congenital hypothyroid TRH receptor 1 knockout (Trhr1 ko) mice and euthyroid control animals. Hypothyroid mice exhibited decreased circulating leptin levels due to a decrease in fat mass and reduced leptin expression in white adipose tissue. In neurons of the hypothalamic arcuate nucleus, hypothyroid mice showed increased leptin receptor Ob-R expression and decreased suppressor of cytokine signaling 3 transcript levels. In order to monitor putative changes in central leptin sensing, we generated hypothyroid and leptin-deficient animals by crossing hypothyroid Trhr1 ko mice with the leptin-deficient ob/ob mice. Hypothyroid Trhr1/ob double knockout mice showed a blunted response to leptin treatment with respect to body weight and food intake and exhibited a decreased activation of phospho-signal transducer and activator of transcription 3 as well as a up-regulation of suppressor of cytokine signaling 3 upon leptin treatment, particularly in the arcuate nucleus. These data indicate alterations in the intracellular processing of the leptin signal under hypothyroid conditions and thereby unravel a novel mode of action by which TH affects energy metabolism.

  15. Age-Dependent Neurochemical Remodeling of Hypothalamic Astrocytes.

    PubMed

    Santos, Camila Leite; Roppa, Paola Haack Amaral; Truccolo, Pedro; Fontella, Fernanda Urruth; Souza, Diogo Onofre; Bobermin, Larissa Daniele; Quincozes-Santos, André

    2017-10-04

    The hypothalamus is a crucial integrative center in the central nervous system, responsible for the regulation of homeostatic activities, including systemic energy balance. Increasing evidence has highlighted a critical role of astrocytes in orchestrating hypothalamic functions; they participate in the modulation of synaptic transmission, metabolic and trophic support to neurons, immune defense, and nutrient sensing. In this context, disturbance of systemic energy homeostasis, which is a common feature of obesity and the aging process, involves inflammatory responses. This may be related to dysfunction of hypothalamic astrocytes. In this regard, the aim of this study was to evaluate the neurochemical properties of hypothalamic astrocyte cultures from newborn, adult, and aged Wistar rats. Age-dependent changes in the regulation of glutamatergic homeostasis, glutathione biosynthesis, amino acid profile, glucose metabolism, trophic support, and inflammatory response were observed. Additionally, signaling pathways including nuclear factor erythroid-derived 2-like 2/heme oxygenase-1 p38 mitogen-activated protein kinase, nuclear factor kappa B, phosphatidylinositide 3-kinase/Akt, and leptin receptor expression may represent putative mechanisms associated with the cellular alterations. In summary, our findings indicate that as age increases, hypothalamic astrocytes remodel and exhibit changes in their neurochemical properties. This process may play a role in the onset and/or progression of metabolic disorders.

  16. Hypothalamic involvement in chronic migraine

    PubMed Central

    Peres, M; del Rio, M S.; Seabra, M; Tufik, S; Abucham, J; Cipolla-Neto, J; Silberstein, S; Zukerman, E

    2001-01-01

    OBJECTIVES—Chronic migraine (CM), previously called transformed migraine, is a frequent headache disorder that affects 2%-3% of the general population. Analgesic overuse, insomnia, depression, and anxiety are disorders that are often comorbid with CM. Hypothalamic dysfunction has been implicated in its pathogenesis, but it has never been studied in patients with CM. The aim was to analyze hypothalamic involvement in CM by measurement of melatonin, prolactin, growth hormone, and cortisol nocturnal secretion.
METHODS—A total of 338 blood samples (13/patient) from 17 patients with CM and nine age and sex matched healthy volunteers were taken. Melatonin, prolactin, growth hormone, and cortisol concentrations were determined every hour for 12 hours. The presence of comorbid disorders was also evaluated.
RESULTS—An abnormal pattern of hypothalamic hormonal secretion was found in CM. This included: (1) a decreased nocturnal prolactin peak, (2) increased cortisol concentrations, (3) a delayed nocturnal melatonin peak in patients with CM, and (4) lower melatonin concentrations in patients with CM with insomnia. Growth hormone secretion did not differ from controls.
CONCLUSION—These results support hypothalamic involvement in CM, shown by a chronobiologic dysregulation, and a possible hyperdopaminergic state in patients with CM. Insomnia might be an important variable in the study findings.

 PMID:11723194

  17. METABOLIC RESPONSES TO DIETARY LEUCINE RESTRICTION INVOLVE REMODELING OF ADIPOSE TISSUE AND ENHANCED HEPATIC INSULIN SIGNALING

    PubMed Central

    Wanders, Desiree; Stone, Kirsten P.; Dille, Kelly; Simon, Jacob; Pierse, Alicia; Gettys, Thomas W.

    2015-01-01

    Dietary leucine was incrementally restricted to test whether limiting this essential amino acid (EAA) would fully reproduce the beneficial responses produced by dietary methionine restriction. Restricting leucine by 85% increased energy intake and expenditure within five to seven days of its introduction and reduced overall accumulation of adipose tissue. Leucine restriction (LR) also improved glucose tolerance, increased hepatic release of FGF21 into the blood stream, and enhanced insulin-dependent activation of Akt in liver. However, LR had no effect on hepatic lipid levels and failed to lower lipogenic gene expression in the liver. LR did affect remodeling of white and brown adipose tissue, increasing expression of both thermogenic and lipogenic genes. These findings illustrate that dietary LR reproduces many but not all of the physiological responses of methionine restriction. The primary differences occur in the liver, where methionine and leucine restriction cause opposite effects on tissue lipid levels and expression of lipogenic genes. Together these findings suggest that the sensing systems which detect and respond to dietary restriction of EAAs act through mechanisms that both leucine and methionine are able to engage, and in the case of hepatic lipid metabolism, may be unique to specific EAAs such as methionine. PMID:26643647

  18. Leucine stimulation of skeletal muscle protein synthesis

    SciTech Connect

    Layman, D.K.; Grogan, C.K.

    1986-03-01

    Previous work in this laboratory has demonstrated a stimulatory effect of leucine on skeletal muscle protein synthesis measured in vitro during catabolic conditions. Studies in other laboratories have consistently found this effect in diaphragm muscle, however, studies examining effects on nitrogen balance or with in vivo protein synthesis in skeletal muscle are equivocal. This experiment was designed to determine the potential of leucine to stimulate skeletal muscle protein synthesis in vivo. Male Sprague-Dawley rats weighing 200 g were fasted for 12 hrs, anesthetized, a jugular cannula inserted, and protein synthesis measured using a primed continuous infusion of /sup 14/C-tyrosine. A plateau in specific activity was reached after 30 to 60 min and maintained for 3 hrs. The leucine dose consisted of a 240 umole priming dose followed by a continuous infusion of 160 umoles/hr. Leucine infusion stimulated protein synthesis in the soleus muscle (28%) and in the red (28%) and white portions (12%) of the gastrocnemius muscle compared with controls infused with only tyrosine. The increased rates of protein synthesis were due to increased incorporation of tyrosine into protein and to decreased specific activity of the free tyrosine pool. These data indicate that infusion of leucine has the potential to stimulate in vivo protein synthesis in skeletal muscles.

  19. Directed evolution of leucine dehydrogenase for improved efficiency of L-tert-leucine synthesis.

    PubMed

    Zhu, Lin; Wu, Zhe; Jin, Jian-Ming; Tang, Shuang-Yan

    2016-07-01

    L-tert-Leucine and its derivatives are used as synthetic building blocks for pharmaceutical active ingredients, chiral auxiliaries, and ligands. Leucine dehydrogenase (LeuDH) is frequently used to prepare L-tert-leucine from the α-keto acid precursor trimethylpyruvate (TMP). In this study, a high-throughput screening method for the L-tert-leucine synthesis reaction based on a spectrophotometric approach was developed. Directed evolution strategy was applied to engineer LeuDH from Lysinibacillus sphaericus for improved efficiency of L-tert-leucine synthesis. After two rounds of random mutagenesis, the specific activity of LeuDH on the substrate TMP was enhanced by more than two-fold, compared with that of the wild-type enzyme, while the activity towards its natural substrate, leucine, decreased. The catalytic efficiencies (k cat/K m) of the best mutant enzyme, H6, on substrates TMP and NADH were all enhanced by more than five-fold as compared with that of the wild-type enzyme. The efficiency of L-tert-leucine synthesis by mutant H6 was significantly improved. A productivity of 1170 g/l/day was achieved for the mutant enzyme H6, compared with 666 g/l/day for the wild-type enzyme.

  20. The behaviour of leucine aminopeptidase towards thionopeptides.

    PubMed Central

    Beattie, R E; Elmore, D T; Williams, C H; Guthrie, D J

    1987-01-01

    Thionoleucine S-anilide (Leut-anilide), Leut-Gly-OEt and Leut-Phe-OMe were synthesized and shown to be competitive inhibitors of leucine aminopeptidase from pig kidney. The kinetics of inhibition were determined in the presence of leucine 4-methylcoumarin-7-amide as substrate. Although the compounds showed only moderate inhibitory potency, it was found that all were resistant to hydrolysis by the enzyme, in contrast with the reported behaviour of some thionopeptide analogues of substrates for other Zn2+-peptidases such as carboxypeptidase A and angiotensin-converting enzyme. PMID:3663153

  1. Hypothalamic neurohormones and immune responses

    PubMed Central

    Quintanar, J. Luis; Guzmán-Soto, Irene

    2013-01-01

    The aim of this review is to provide a comprehensive examination of the current literature describing the neural-immune interactions, with emphasis on the most recent findings of the effects of neurohormones on immune system. Particularly, the role of hypothalamic hormones such as Thyrotropin-releasing hormone (TRH), Corticotropin-releasing hormone (CRH) and Gonadotropin-releasing hormone (GnRH). In the past few years, interest has been raised in extrapituitary actions of these neurohormones due to their receptors have been found in many non-pituitary tissues. Also, the receptors are present in immune cells, suggesting an autocrine or paracrine role within the immune system. In general, these neurohormones have been reported to exert immunomodulatory effects on cell proliferation, immune mediators release and cell function. The implications of these findings in understanding the network of hypothalamic neuropeptides and immune system are discussed. PMID:23964208

  2. Hypothalamic neurohormones and immune responses.

    PubMed

    Quintanar, J Luis; Guzmán-Soto, Irene

    2013-01-01

    The aim of this review is to provide a comprehensive examination of the current literature describing the neural-immune interactions, with emphasis on the most recent findings of the effects of neurohormones on immune system. Particularly, the role of hypothalamic hormones such as Thyrotropin-releasing hormone (TRH), Corticotropin-releasing hormone (CRH) and Gonadotropin-releasing hormone (GnRH). In the past few years, interest has been raised in extrapituitary actions of these neurohormones due to their receptors have been found in many non-pituitary tissues. Also, the receptors are present in immune cells, suggesting an autocrine or paracrine role within the immune system. In general, these neurohormones have been reported to exert immunomodulatory effects on cell proliferation, immune mediators release and cell function. The implications of these findings in understanding the network of hypothalamic neuropeptides and immune system are discussed.

  3. 21 CFR 582.5406 - Leucine.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Leucine. 582.5406 Section 582.5406 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements...

  4. 21 CFR 582.5406 - Leucine.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Leucine. 582.5406 Section 582.5406 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1...

  5. 21 CFR 582.5406 - Leucine.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Leucine. 582.5406 Section 582.5406 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1...

  6. 21 CFR 582.5406 - Leucine.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Leucine. 582.5406 Section 582.5406 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1...

  7. 21 CFR 582.5406 - Leucine.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Leucine. 582.5406 Section 582.5406 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1...

  8. Hypothalamic thermosensitivity in capsaicin-desensitized rats.

    PubMed Central

    Cormarèche-Leydier, M; Shimada, S G; Stitt, J T

    1985-01-01

    In rats, we tested the hypothesis that capsaicin desensitization reduces hypothalamic warm thermosensitivity. We locally heated and cooled the hypothalamus using water-perfused thermodes while observing thermoregulatory variables. In untreated rats, a small dose of capsaicin had profound effects on thermoregulation. However, desensitizing rats to capsaicin had no effect on hypothalamic thermosensitivity for metabolic rate or changes in body temperature due to displacements of hypothalamic temperature. Contrary to current opinion, we conclude that capsaicin desensitization does not alter hypothalamic thermosensitivity to warm or cold. PMID:4020699

  9. Glucose and hypothalamic astrocytes: More than a fueling role?

    PubMed

    Leloup, C; Allard, C; Carneiro, L; Fioramonti, X; Collins, S; Pénicaud, L

    2016-05-26

    Brain plays a central role in energy homeostasis continuously integrating numerous peripheral signals such as circulating nutrients, and in particular blood glucose level, a variable that must be highly regulated. Then, the brain orchestrates adaptive responses to modulate food intake and peripheral organs activity in order to achieve the fine tuning of glycemia. More than fifty years ago, the presence of glucose-sensitive neurons was discovered in the hypothalamus, but what makes them specific and identifiable still remains disconnected from their electrophysiological signature. On the other hand, astrocytes represent the major class of macroglial cells and are now recognized to support an increasing number of neuronal functions. One of these functions consists in the regulation of energy homeostasis through neuronal fueling and nutrient sensing. Twenty years ago, we discovered that the glucose transporter GLUT2, the canonical "glucosensor" of the pancreatic beta-cell together with the glucokinase, was also present in astrocytes and participated in hypothalamic glucose sensing. Since then, many studies have identified other actors and emphasized the astroglial participation in this mechanism. Growing evidence suggest that astrocytes form a complex network and have to be considered as spatially coordinated and regulated metabolic units. In this review we aim to provide an updated view of the molecular and respective cellular pathways involved in hypothalamic glucose sensing, and their relevance in physiological and pathological states.

  10. Bariatric Surgery in Hypothalamic Obesity

    PubMed Central

    Bingham, Nathan C.; Rose, Susan R.; Inge, Thomas H.

    2012-01-01

    Craniopharyngiomas (CP) are epithelial neoplasms generally found in the area of the pituitary and hypothalamus. Despite benign histology, these tumors and/or their treatment often result in significant, debilitating disorders of endocrine, neurological, behavioral, and metabolic systems. Severe obesity is observed in a high percentage of patients with CP resulting in significant comorbidities and negatively impacting quality of life. Obesity occurs as a result of hypothalamic damage and disruption of normal homeostatic mechanisms regulating energy balance. Such pathological weight gain, termed hypothalamic obesity (HyOb), is often severe and refractory to therapy. Unfortunately, neither lifestyle intervention nor pharmacotherapy has proven effective in the treatment of HyOb. Given the limited choices and poor results of these treatments, several groups have examined bariatric surgery as a treatment alternative for patients with CP–HyOb. While a large body of evidence exists supporting the use of bariatric surgery in the treatment of exogenous obesity and its comorbidities, its role in the treatment of HyOb has yet to be defined. To date, the existing literature on bariatric surgery in CP–HyOb is largely limited to case reports and series with short term follow-up. Here we review the current reports on the use of bariatric surgery in the treatment of CP–HyOb. We also compare these results to those reported for other populations of HyOb, including Prader–Willi Syndrome, Bardet–Biedl syndrome, and hypothalamic melanocortin signaling defects. While initial reports of bariatric surgery in CP–HyOb are promising, their limited scope makes it difficult to draw any substantial conclusions as to the long term safety and efficacy of bariatric surgery in CP–HyOb. There continues to be a need for more robust, controlled, prospective studies with long term follow-up in order to better define the role of bariatric surgery in the treatment of HyOb. PMID:22649412

  11. Bariatric surgery in hypothalamic obesity.

    PubMed

    Bingham, Nathan C; Rose, Susan R; Inge, Thomas H

    2012-01-01

    Craniopharyngiomas (CP) are epithelial neoplasms generally found in the area of the pituitary and hypothalamus. Despite benign histology, these tumors and/or their treatment often result in significant, debilitating disorders of endocrine, neurological, behavioral, and metabolic systems. Severe obesity is observed in a high percentage of patients with CP resulting in significant comorbidities and negatively impacting quality of life. Obesity occurs as a result of hypothalamic damage and disruption of normal homeostatic mechanisms regulating energy balance. Such pathological weight gain, termed hypothalamic obesity (HyOb), is often severe and refractory to therapy. Unfortunately, neither lifestyle intervention nor pharmacotherapy has proven effective in the treatment of HyOb. Given the limited choices and poor results of these treatments, several groups have examined bariatric surgery as a treatment alternative for patients with CP-HyOb. While a large body of evidence exists supporting the use of bariatric surgery in the treatment of exogenous obesity and its comorbidities, its role in the treatment of HyOb has yet to be defined. To date, the existing literature on bariatric surgery in CP-HyOb is largely limited to case reports and series with short term follow-up. Here we review the current reports on the use of bariatric surgery in the treatment of CP-HyOb. We also compare these results to those reported for other populations of HyOb, including Prader-Willi Syndrome, Bardet-Biedl syndrome, and hypothalamic melanocortin signaling defects. While initial reports of bariatric surgery in CP-HyOb are promising, their limited scope makes it difficult to draw any substantial conclusions as to the long term safety and efficacy of bariatric surgery in CP-HyOb. There continues to be a need for more robust, controlled, prospective studies with long term follow-up in order to better define the role of bariatric surgery in the treatment of HyOb.

  12. FLCN Maintains the Leucine Level in Lysosome to Stimulate mTORC1

    PubMed Central

    Chen, Zhi; Ji, Xin; Qiao, Xianfeng; Jin, Yaping; Liu, Wei

    2016-01-01

    The intracellular amino acid pool within lysosome is a signal that stimulates the nutrient-sensing mTORC1 signalling pathway. The signal transduction cascade has garnered much attention, but little is known about the sequestration of the signalling molecules within the lysosome. Using human HEK293 cells as a model, we found that suppression of the BHD syndrome gene FLCN reduced the leucine level in lysosome, which correlated with decreased mTORC1 activity. Both consequences could be reversed by supplementation with high levels of leucine, but not other tested amino acids. Conversely, overexpressed FLCN could sequester lysosomal leucine and stimulate mTORC1 in an amino acid limitation environment. These results identify a novel function of FLCN: it controls mTORC1 by modulating the leucine signal in lysosome. Furthermore, we provided evidence that FLCN exerted this role by inhibiting the accumulation of the amino acid transporter PAT1 on the lysosome surface, thereby maintaining the signal level within the organelle. PMID:27280402

  13. Metabolic responses to dietary leucine restriction involve remodeling of adipose tissue and enhanced hepatic insulin signaling.

    PubMed

    Wanders, Desiree; Stone, Kirsten P; Dille, Kelly; Simon, Jacob; Pierse, Alicia; Gettys, Thomas W

    2015-01-01

    Dietary leucine was incrementally restricted to test whether limiting this essential amino acid (EAA) would fully reproduce the beneficial responses produced by dietary methionine restriction. Restricting leucine by 85% increased energy intake and expenditure within 5 to 7 days of its introduction and reduced overall accumulation of adipose tissue. Leucine restriction (LR) also improved glucose tolerance, increased hepatic release of fibroblast growth factor 21 into the blood stream, and enhanced insulin-dependent activation of Akt in liver. However, LR had no effect on hepatic lipid levels and failed to lower lipogenic gene expression in the liver. LR did affect remodeling of white and brown adipose tissues, increasing expression of both thermogenic and lipogenic genes. These findings illustrate that dietary LR reproduces many but not all of the physiological responses of methionine restriction. The primary differences occur in the liver, where methionine and LR cause opposite effects on tissue lipid levels and expression of lipogenic genes. Altogether, these findings suggest that the sensing systems which detect and respond to dietary restriction of EAAs act through mechanisms that both leucine and methionine are able to engage, and in the case of hepatic lipid metabolism, may be unique to specific EAAs such as methionine. © 2015 International Union of Biochemistry and Molecular Biology.

  14. Hypothalamic miRNAs: emerging roles in energy balance control.

    PubMed

    Schneeberger, Marc; Gomez-Valadés, Alicia G; Ramirez, Sara; Gomis, Ramon; Claret, Marc

    2015-01-01

    The hypothalamus is a crucial central nervous system area controlling appetite, body weight and metabolism. It consists in multiple neuronal types that sense, integrate and generate appropriate responses to hormonal and nutritional signals partly by fine-tuning the expression of specific batteries of genes. However, the mechanisms regulating these neuronal gene programmes in physiology and pathophysiology are not completely understood. MicroRNAs (miRNAs) are key regulators of gene expression that recently emerged as pivotal modulators of systemic metabolism. In this article we will review current evidence indicating that miRNAs in hypothalamic neurons are also implicated in appetite and whole-body energy balance control.

  15. Impact of leucine on energy balance.

    PubMed

    McAllan, Liam; Cotter, Paul D; Roche, Helen M; Korpela, Riitta; Nilaweera, Kanishka N

    2013-03-01

    Body weight is determined by the balance between energy intake and energy expenditure. When energy intake exceeds energy expenditure, the surplus energy is stored as fat in the adipose tissue, which causes its expansion and may even lead to the development of obesity. Thus, there is a growing interest to develop dietary interventions that could reduce the current obesity epidemic. In this regard, data from a number of in vivo and in vitro studies suggest that the branched-chain amino acid leucine influences energy balance. However, this has not been consistently reported. Here, we review the literature related to the effects of leucine on energy intake, energy expenditure and lipid metabolism as well as its effects on the cellular activity in the brain (hypothalamus) and in peripheral tissues (gastro-intestinal tract, adipose tissue, liver and muscle) regulating the above physiological processes. Moreover, we discuss how obesity may influence the actions of this amino acid.

  16. Age Attenuates Leucine Oxidation after Eccentric Exercise

    PubMed Central

    Kullman, E. L.; Campbell, W. W.; Krishnan, R. K.; Yarasheski, K. E.; Evans, W. J.; Kirwan, J. P.

    2013-01-01

    Aging may alter protein metabolism during periods of metabolic and physiologic challenge. The purpose of this study was to assess the effects of age on whole-body amino acid turnover in response to eccentric exercise and hyperglycemia-induced hyperinsulinemia. 16 healthy men were divided into young (N = 8) and older (N = 8) groups. Protein metabolism was assessed using a [1-13C]-leucine isotopic tracer approach. Measures were obtained under fasted basal conditions and during 3-h hyperglycemic clamps that were performed without (control) and 48 h after eccentric exercise. Exercise reduced leucine oxidation in the younger men (P < 0.05), but not in older men. Insulin sensitivity was inversely correlated with leucine oxidation (P < 0.05), and was lower in older men (P < 0.05). Healthy aging is associated with an impaired capacity to adjust protein oxidation in response to eccentric exercise. The decreased efficiency of protein utilization in older men may contribute to impaired maintenance, growth, and repair of body tissues with advancing age. PMID:23325713

  17. Mitochondrial leucine tRNA level and PTCD1 are regulated in response to leucine starvation.

    PubMed

    Schild, Christof; Hahn, Dagmar; Schaller, André; Jackson, Christopher Benjamin; Rothen-Rutishauser, Barbara; Mirkovitch, Jelena; Nuoffer, Jean-Marc

    2014-07-01

    Pentatricopeptide repeat domain protein 1 (PTCD1) is a novel human protein that was recently shown to decrease the levels of mitochondrial leucine tRNAs. The physiological role of this regulation, however, remains unclear. Here we show that amino acid starvation by leucine deprivation significantly increased the mRNA steady-state levels of PTCD1 in human hepatocarcinoma (HepG2) cells. Amino acid starvation also increased the mitochondrially encoded leucine tRNA (tRNA(Leu(CUN))) and the mRNA for the mitochondrial leucyl-tRNA synthetase (LARS2). Despite increased PTCD1 mRNA steady-state levels, amino acid starvation decreased PTCD1 on the protein level. Decreasing PTCD1 protein concentration increases the stability of the mitochondrial leucine tRNAs, tRNA(Leu(CUN)) and tRNA(Leu(UUR)) as could be shown by RNAi experiments against PTCD1. Therefore, it is likely that decreased PTCD1 protein contributes to the increased tRNA(Leu(CUN)) levels in amino acid-starved cells. The stabilisation of the mitochondrial leucine tRNAs and the upregulation of the mitochondrial leucyl-tRNA synthetase LARS2 might play a role in adaptation of mitochondria to amino acid starvation.

  18. Estrogens modulate ventrolateral ventromedial hypothalamic glucose-inhibited neurons.

    PubMed

    Santiago, Ammy M; Clegg, Deborah J; Routh, Vanessa H

    2016-10-01

    Brain regulation of glucose homeostasis is sexually dimorphic; however, the impact sex hormones have on specific neuronal populations within the ventromedial hypothalamic nucleus (VMN), a metabolically sensitive brain region, has yet to be fully characterized. Glucose-excited (GE) and -inhibited (GI) neurons are located throughout the VMN and may play a critical role in glucose and energy homeostasis. Within the ventrolateral portion of the VMN (VL-VMN), glucose sensing neurons and estrogen receptor (ER) distributions overlap. We therefore tested the hypothesis that VL-VMN glucose sensing neurons were sexually dimorphic and regulated by 17β-estradiol (17βE). Electrophysiological recordings of VL-VMN glucose sensing neurons in brain slices isolated from age- and weight-matched female and male mice were performed in the presence and absence of 17βE. We found a new class of VL-VMN GI neurons whose response to low glucose was transient despite continued exposure to low glucose. Heretofore, we refer to these newly identified VL-VMN GI neurons as 'adapting' or AdGI neurons. We found a sexual dimorphic response to low glucose, with male nonadapting GI neurons, but not AdGI neurons, responding more robustly to low glucose than those from females. 17βE blunted the response of both nonadapting GI and AdGI neurons to low glucose in both males and females, which was mediated by activation of estrogen receptor β and inhibition of AMP-activated kinase. In contrast, 17βE had no impact on GE or non-glucose sensing neurons in either sex. These data suggest sex differences and estrogenic regulation of VMN hypothalamic glucose sensing may contribute to the sexual dimorphism in glucose homeostasis.

  19. Hypothalamic eIF2α Signaling Regulates Food Intake

    PubMed Central

    Maurin, Anne-Catherine; Benani, Alexandre; Lorsignol, Anne; Brenachot, Xavier; Parry, Laurent; Carraro, Valérie; Guissard, Christophe; Averous, Julien; Jousse, Céline; Bruhat, Alain; Chaveroux, Cédric; B’chir, Wafa; Muranishi, Yuki; Ron, David; Pénicaud, Luc; Fafournoux, Pierre

    2016-01-01

    Summary The reversible phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α) is a highly conserved signal implicated in the cellular adaptation to numerous stresses such as the one caused by amino acid limitation. In response to dietary amino acid deficiency, the brain-specific activation of the eIF2α kinase GCN2 leads to food intake inhibition. We report here that GCN2 is rapidly activated in the mediobasal hypothalamus (MBH) after consumption of a leucine-deficient diet. Furthermore, knockdown of GCN2 in this particular area shows that MBH GCN2 activity controls the onset of the aversive response. Importantly, pharmacological experiments demonstrate that the sole phosphorylation of eIF2α in the MBH is sufficient to regulate food intake. eIF2α signaling being at the crossroad of stress pathways activated in several pathological states, our study indicates that hypothalamic eIF2α phosphorylation could play a critical role in the onset of anorexia associated with certain diseases. PMID:24485657

  20. Hypothalamic control of bone metabolism.

    PubMed

    Sharan, Kunal; Yadav, Vijay K

    2014-10-01

    Bones are structures in vertebrates that provide support to organs, protect soft organs, and give them shape and defined features, functions that are essential for their survival. To perform these functions, bones are constantly renewed throughout life. The process through which bones are renewed is known as bone remodeling, an energy demanding process sensitive to changes in energy homeostasis of the organism. A close interplay takes place between the diversity of nutritional cues and metabolic signals with different elements of the hypothalamic circuits to co-ordinate energy metabolism with the regulation of bone mass. In this review, we focus on how mouse and human genetics have elucidated the roles of hormonal signals and neural circuits that originate in, or impinge on, the hypothalamus in the regulation of bone mass. This will help to understand the mechanisms whereby regulation of bone is gated and dynamically regulated by the hypothalamus.

  1. Failure of leucine to stimulate protein synthesis in vivo.

    PubMed Central

    McNurlan, M A; Fern, E B; Garlick, P J

    1982-01-01

    The effect of 100 mumol of leucine on protein synthesis in several tissues was assessed in the intact rat. Leucine had no immediate effect on protein synthesis in gastrocnemius muscle, heart, jejunal serosa, jejunal mucosa or liver in rats which were fed, starved for 2 days or deprived of dietary protein for 9 days. Leucine treatment for 1 h also failed to stimulate protein synthesis in tissues of 2-day-starved animals. PMID:7126170

  2. Potent anti-seizure effects of D-leucine

    PubMed Central

    Hartman, Adam L.; Santos, Polan; O’Riordan, Kenneth J.; Stafstrom, Carl E.; Hardwick, J. Marie

    2015-01-01

    There are no effective treatments for millions of patients with intractable epilepsy. High-fat ketogenic diets may provide significant clinical benefit but are challenging to implement. Low carbohydrate levels appear to be essential for the ketogenic diet to work, but the active ingredients in dietary interventions remain elusive, and a role for ketogenesis has been challenged. A potential antiseizure role of dietary protein or of individual amino acids in the ketogenic diet is understudied. We investigated the two exclusively ketogenic amino acids, L-leucine and L-lysine, and found that only L-leucine potently protects mice when administered prior to the onset of seizures induced by kainic acid injection, but not by inducing ketosis. Unexpectedly, the D-enantiomer of leucine, which is found in trace amounts in the brain, worked as well or better than L-leucine against both kainic acid and 6 Hz electroshock-induced seizures. However, unlike L-leucine, D-leucine potently terminated seizures even after the onset of seizure activity. Furthermore, D-leucine, but not L-leucine, reduced long-term potentiation but had no effect on basal synaptic transmission in vitro. In a screen of candidate neuronal receptors, D-leucine failed to compete for binding by cognate ligands, potentially suggesting a novel target. Even at low doses, D-leucine suppressed ongoing seizures at least as effectively as diazepam but without sedative effects. These studies raise the possibility that D-leucine may represent a new class of anti-seizure agents, and that D-leucine may have a previously unknown function in eukaryotes. PMID:26054437

  3. Potent anti-seizure effects of D-leucine.

    PubMed

    Hartman, Adam L; Santos, Polan; O'Riordan, Kenneth J; Stafstrom, Carl E; Hardwick, J Marie

    2015-10-01

    There are no effective treatments for millions of patients with intractable epilepsy. High-fat ketogenic diets may provide significant clinical benefit but are challenging to implement. Low carbohydrate levels appear to be essential for the ketogenic diet to work, but the active ingredients in dietary interventions remain elusive, and a role for ketogenesis has been challenged. A potential antiseizure role of dietary protein or of individual amino acids in the ketogenic diet is understudied. We investigated the two exclusively ketogenic amino acids, L-leucine and L-lysine, and found that only L-leucine potently protects mice when administered prior to the onset of seizures induced by kainic acid injection, but not by inducing ketosis. Unexpectedly, the D-enantiomer of leucine, which is found in trace amounts in the brain, worked as well or better than L-leucine against both kainic acid and 6Hz electroshock-induced seizures. However, unlike L-leucine, D-leucine potently terminated seizures even after the onset of seizure activity. Furthermore, D-leucine, but not L-leucine, reduced long-term potentiation but had no effect on basal synaptic transmission in vitro. In a screen of candidate neuronal receptors, D-leucine failed to compete for binding by cognate ligands, potentially suggesting a novel target. Even at low doses, D-leucine suppressed ongoing seizures at least as effectively as diazepam but without sedative effects. These studies raise the possibility that D-leucine may represent a new class of anti-seizure agents, and that D-leucine may have a previously unknown function in eukaryotes.

  4. Leucine Supplementation Improves Skeletal Muscle Regeneration after Cryolesion in Rats

    PubMed Central

    Pereira, Marcelo G.; Baptista, Igor L.; Carlassara, Eduardo O. C.; Moriscot, Anselmo S.; Aoki, Marcelo S.; Miyabara, Elen H.

    2014-01-01

    This study was undertaken in order to provide further insight into the role of leucine supplementation in the skeletal muscle regeneration process, focusing on myofiber size and strength recovery. Young (2-month-old) rats were subjected or not to leucine supplementation (1.35 g/kg per day) started 3 days prior to cryolesion. Then, soleus muscles were cryolesioned and continued receiving leucine supplementation until 1, 3 and 10 days later. Soleus muscles from leucine-supplemented animals displayed an increase in myofiber size and a reduction in collagen type III expression on post-cryolesion day 10. Leucine was also effective in reducing FOXO3a activation and ubiquitinated protein accumulation in muscles at post-cryolesion days 3 and 10. In addition, leucine supplementation minimized the cryolesion-induced decrease in tetanic strength and increase in fatigue in regenerating muscles at post-cryolesion day 10. These beneficial effects of leucine were not accompanied by activation of any elements of the phosphoinositide 3-kinase/Akt/mechanistic target of rapamycin signalling pathway in the regenerating muscles. Our results show that leucine improves myofiber size gain and strength recovery in regenerating soleus muscles through attenuation of protein ubiquitination. In addition, leucine might have therapeutic effects for muscle recovery following injury and in some muscle diseases. PMID:24416379

  5. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., plasma, and urine. Leucine aminopeptidase measurements are used in the diagnosis and treatment of liver diseases such as viral hepatitis and obstructive jaundice. (b) Classification. Class I (general...

  6. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., plasma, and urine. Leucine aminopeptidase measurements are used in the diagnosis and treatment of liver diseases such as viral hepatitis and obstructive jaundice. (b) Classification. Class I (general...

  7. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., plasma, and urine. Leucine aminopeptidase measurements are used in the diagnosis and treatment of liver diseases such as viral hepatitis and obstructive jaundice. (b) Classification. Class I (general...

  8. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., plasma, and urine. Leucine aminopeptidase measurements are used in the diagnosis and treatment of liver diseases such as viral hepatitis and obstructive jaundice. (b) Classification. Class I (general...

  9. Molecular cloning of adipocyte-derived leucine aminopeptidase highly related to placental leucine aminopeptidase/oxytocinase.

    PubMed

    Hattori, A; Matsumoto, H; Mizutani, S; Tsujimoto, M

    1999-05-01

    In the current study, we report the cloning and initial characterization of a novel human cytosolic aminopeptidase named adipocyte-derived leucine aminopeptidase (A-LAP). The sequence encodes a 941-amino acid protein with significant homology (43%) to placental leucine aminopeptidase (P-LAP)/oxytocinase. The predicted A-LAP contains the HEXXH(X)18E consensus sequence, which is characteristic of the M1 family of zinc-metallopeptidases. Although the deduced sequence contains a hydrophobic region near the N-terminus, the enzyme localized mainly in cytoplasm when expressed in COS-7 cells. Northern blot analysis revealed that A-LAP was expressed in all the tissues tested, some of which expressed at least three forms of mRNA, suggesting that the regulation of the gene expression is complex. When aminopeptidase activity of A-LAP was measured with various synthetic substrates, the enzyme revealed a preference for leucine, establishing that A-LAP is a novel leucine aminopeptidase with restricted substrate specificity. The identification of A-LAP, which reveals strong homology to P-LAP, might lead to the definition of a new subfamily of zinc-containing aminopeptidases belonging to the M1 family of metallopeptidases.

  10. Defective regulation of POMC precedes hypothalamic inflammation in diet-induced obesity

    PubMed Central

    Souza, Gabriela F. P.; Solon, Carina; Nascimento, Lucas F.; De-Lima-Junior, Jose C.; Nogueira, Guilherme; Moura, Rodrigo; Rocha, Guilherme Z.; Fioravante, Milena; Bobbo, Vanessa; Morari, Joseane; Razolli, Daniela; Araujo, Eliana P.; Velloso, Licio A.

    2016-01-01

    Obesity is the result of a long-term positive energy balance in which caloric intake overrides energy expenditure. This anabolic state results from the defective activity of hypothalamic neurons involved in the sensing and response to adiposity. However, it is currently unknown what the earliest obesity-linked hypothalamic defect is and how it orchestrates the energy imbalance present in obesity. Using an outbred model of diet-induced obesity we show that defective regulation of hypothalamic POMC is the earliest marker distinguishing obesity-prone from obesity-resistant mice. The early inhibition of hypothalamic POMC was sufficient to transform obesity-resistant in obesity-prone mice. In addition, the post-prandial change in the blood level of β-endorphin, a POMC-derived peptide, correlates with body mass gain in rodents and humans. Taken together, these results suggest that defective regulation of POMC expression, which leads to a change of β-endorphin levels, is the earliest hypothalamic defect leading to obesity. PMID:27373214

  11. Elevated Hypothalamic Glucocorticoid Levels Are Associated With Obesity and Hyperphagia in Male Mice

    PubMed Central

    Sefton, Charlotte; Harno, Erika; Davies, Alison; Small, Helen; Allen, Tiffany-Jayne; Wray, Jonathan R.; Lawrence, Catherine B.; Coll, Anthony P.

    2016-01-01

    Glucocorticoid (Gc) excess, from endogenous overproduction in disorders of the hypothalamic-pituitary-adrenal axis or exogenous medical therapy, is recognized to cause adverse metabolic side effects. The Gc receptor (GR) is widely expressed throughout the body, including brain regions such as the hypothalamus. However, the extent to which chronic Gcs affect Gc concentrations in the hypothalamus and impact on GR and target genes is unknown. To investigate this, we used a murine model of corticosterone (Cort)-induced obesity and analyzed Cort levels in the hypothalamus and expression of genes relevant to Gc action. Mice were administered Cort (75 μg/mL) or ethanol (1%, vehicle) in drinking water for 4 weeks. Cort-treated mice had increased body weight, food intake, and adiposity. As expected, Cort increased plasma Cort levels at both zeitgeber time 1 and zeitgeber time 13, ablating the diurnal rhythm. Liquid chromatography dual tandem mass spectrometry revealed a 4-fold increase in hypothalamic Cort, which correlated with circulating levels and concentrations of Cort in other brain regions. This occurred despite decreased 11β-hydroxysteroid dehydrogenase (Hsd11b1) expression, the gene encoding the enzyme that regenerates active Gcs, whereas efflux transporter Abcb1 mRNA was unaltered. In addition, although Cort decreased hypothalamic GR (Nr3c1) expression 2-fold, the Gc-induced leucine zipper (Tsc22d3) mRNA increased, which indicated elevated GR activation. In keeping with the development of hyperphagia and obesity, Cort increased Agrp, but there were no changes in Pomc, Npy, or Cart mRNA in the hypothalamus. In summary, chronic Cort treatment causes chronic increases in hypothalamic Cort levels and a persistent elevation in Agrp, a mediator in the development of metabolic disturbances. PMID:27649090

  12. Structure-activity relations of leucine derivatives reveal critical moieties for cellular uptake and activation of mTORC1-mediated signaling.

    PubMed

    Nagamori, Shushi; Wiriyasermkul, Pattama; Okuda, Suguru; Kojima, Naoto; Hari, Yoshiyuki; Kiyonaka, Shigeki; Mori, Yasuo; Tominaga, Hideyuki; Ohgaki, Ryuichi; Kanai, Yoshikatsu

    2016-04-01

    Among amino acids, leucine is a potential signaling molecule to regulate cell growth and metabolism by activating mechanistic target of rapamycin complex 1 (mTORC1). To reveal the critical structures of leucine molecule to activate mTORC1, we examined the structure-activity relationships of leucine derivatives in HeLa S3 cells for cellular uptake and for the induction of phosphorylation of p70 ribosomal S6 kinase 1 (p70S6K), a downstream effector of mTORC1. The activation of mTORC1 by leucine and its derivatives was the consequence of two successive events: the cellular uptake by L-type amino acid transporter 1 (LAT1) responsible for leucine uptake in HeLa S3 cells and the activation of mTORC1 following the transport. The structural requirement for the recognition by LAT1 was to have carbonyl oxygen, alkoxy oxygen of carboxyl group, amino group and hydrophobic side chain. In contrast, the requirement for mTORC1 activation was more rigorous. It additionally required fixed distance between carbonyl oxygen and alkoxy oxygen of carboxyl group, and amino group positioned at α-carbon. L-Configuration in chirality and appropriate length of side chain with a terminal isopropyl group were also important. This confirmed that LAT1 itself is not a leucine sensor. Some specialized leucine sensing mechanism with rigorous requirement for agonistic structures should exist inside the cells because leucine derivatives not transported by LAT1 did not activate mTORC1. Because LAT1-mTOR axis is involved in the regulation of cell growth and cancer progression, the results from this study may provide a new insight into therapeutics targeting both LAT1 and leucine sensor.

  13. B(0)AT2 (SLC6A15) is localized to neurons and astrocytes, and is involved in mediating the effect of leucine in the brain.

    PubMed

    Hägglund, Maria G A; Roshanbin, Sahar; Löfqvist, Erik; Hellsten, Sofie V; Nilsson, Victor C O; Todkar, Aniruddha; Zhu, Yinan; Stephansson, Olga; Drgonova, Jana; Uhl, George R; Schiöth, Helgi B; Fredriksson, Robert

    2013-01-01

    The B(0)AT2 protein is a product of the SLC6A15 gene belonging to the SLC6 subfamily and has been shown to be a transporter of essential branched-chain amino acids. We aimed to further characterize the B(0)AT2 transporter in CNS, and to use Slc6a15 knock out (KO) mice to investigate whether B(0)AT2 is important for mediating the anorexigenic effect of leucine. We used the Slc6a15 KO mice to investigate the role of B(0)AT2 in brain in response to leucine and in particular the effect on food intake. Slc6a15 KO mice show lower reduction of food intake as well as lower neuronal activation in the ventromedial hypothalamic nucleus (VMH) in response to leucine injections compared to wild type mice. We also used RT-PCR on rat tissues, in situ hybridization and immunohistochemistry on mouse CNS tissues to document in detail the distribution of SLC6A15 on gene and protein levels. We showed that B(0)AT2 immunoreactivity is mainly neuronal, including localization in many GABAergic neurons and spinal cord motor neurons. B(0)AT2 immunoreactivity was also found in astrocytes close to ventricles, and co-localized with cytokeratin and diazepam binding inhibitor (DBI) in epithelial cells of the choroid plexus. The data suggest that B(0)AT2 play a role in leucine homeostasis in the brain.

  14. B0AT2 (SLC6A15) Is Localized to Neurons and Astrocytes, and Is Involved in Mediating the Effect of Leucine in the Brain

    PubMed Central

    Hägglund, Maria G. A.; Roshanbin, Sahar; Löfqvist, Erik; Hellsten, Sofie V.; Nilsson, Victor C. O.; Todkar, Aniruddha; Zhu, Yinan; Stephansson, Olga; Drgonova, Jana; Uhl, George R.; Schiöth, Helgi B.; Fredriksson, Robert

    2013-01-01

    The B0AT2 protein is a product of the SLC6A15 gene belonging to the SLC6 subfamily and has been shown to be a transporter of essential branched-chain amino acids. We aimed to further characterize the B0AT2 transporter in CNS, and to use Slc6a15 knock out (KO) mice to investigate whether B0AT2 is important for mediating the anorexigenic effect of leucine. We used the Slc6a15 KO mice to investigate the role of B0AT2 in brain in response to leucine and in particular the effect on food intake. Slc6a15 KO mice show lower reduction of food intake as well as lower neuronal activation in the ventromedial hypothalamic nucleus (VMH) in response to leucine injections compared to wild type mice. We also used RT-PCR on rat tissues, in situ hybridization and immunohistochemistry on mouse CNS tissues to document in detail the distribution of SLC6A15 on gene and protein levels. We showed that B0AT2 immunoreactivity is mainly neuronal, including localization in many GABAergic neurons and spinal cord motor neurons. B0AT2 immunoreactivity was also found in astrocytes close to ventricles, and co-localized with cytokeratin and diazepam binding inhibitor (DBI) in epithelial cells of the choroid plexus. The data suggest that B0AT2 play a role in leucine homeostasis in the brain. PMID:23505546

  15. Neuropeptide Y stimulates autophagy in hypothalamic neurons

    PubMed Central

    Aveleira, Célia A.; Botelho, Mariana; Carmo-Silva, Sara; Ferreira-Marques, Marisa; Nóbrega, Clévio; Cortes, Luísa; Valero, Jorge; Sousa-Ferreira, Lígia; Álvaro, Ana R.; Santana, Magda; Kügler, Sebastian; Pereira de Almeida, Luís

    2015-01-01

    Aging is characterized by autophagy impairment that contributes to age-related disease aggravation. Moreover, it was described that the hypothalamus is a critical brain area for whole-body aging development and has impact on lifespan. Neuropeptide Y (NPY) is one of the major neuropeptides present in the hypothalamus, and it has been shown that, in aged animals, the hypothalamic NPY levels decrease. Because caloric restriction (CR) delays aging, at least in part, by stimulating autophagy, and also increases hypothalamic NPY levels, we hypothesized that NPY could have a relevant role on autophagy modulation in the hypothalamus. Therefore, the aim of this study was to investigate the role of NPY on autophagy in the hypothalamus. Using both hypothalamic neuronal in vitro models and mice overexpressing NPY in the hypothalamus, we observed that NPY stimulates autophagy in the hypothalamus. Mechanistically, in rodent hypothalamic neurons, NPY increases autophagy through the activation of NPY Y1 and Y5 receptors, and this effect is tightly associated with the concerted activation of PI3K, MEK/ERK, and PKA signaling pathways. Modulation of hypothalamic NPY levels may be considered a potential strategy to produce protective effects against hypothalamic impairments associated with age and to delay aging. PMID:25775546

  16. Leucine acts as a nutrient signal to stimulate protein synthesis

    USDA-ARS?s Scientific Manuscript database

    The postprandial rise in amino acids and insulin independently stimulates protein synthesis in skeletal muscle of piglets. Leucine is an important mediator of the response to amino acids. We have shown that the postprandial rise in leucine, but not isoleucine or valine, acutely stimulates muscle pro...

  17. Hypothalamic carnitine metabolism integrates nutrient and hormonal feedback to regulate energy homeostasis.

    PubMed

    Stark, Romana; Reichenbach, Alex; Andrews, Zane B

    2015-12-15

    The maintenance of energy homeostasis requires the hypothalamic integration of nutrient feedback cues, such as glucose, fatty acids, amino acids, and metabolic hormones such as insulin, leptin and ghrelin. Although hypothalamic neurons are critical to maintain energy homeostasis research efforts have focused on feedback mechanisms in isolation, such as glucose alone, fatty acids alone or single hormones. However this seems rather too simplistic considering the range of nutrient and endocrine changes associated with different metabolic states, such as starvation (negative energy balance) or diet-induced obesity (positive energy balance). In order to understand how neurons integrate multiple nutrient or hormonal signals, we need to identify and examine potential intracellular convergence points or common molecular targets that have the ability to sense glucose, fatty acids, amino acids and hormones. In this review, we focus on the role of carnitine metabolism in neurons regulating energy homeostasis. Hypothalamic carnitine metabolism represents a novel means for neurons to facilitate and control both nutrient and hormonal feedback. In terms of nutrient regulation, carnitine metabolism regulates hypothalamic fatty acid sensing through the actions of CPT1 and has an underappreciated role in glucose sensing since carnitine metabolism also buffers mitochondrial matrix levels of acetyl-CoA, an allosteric inhibitor of pyruvate dehydrogenase and hence glucose metabolism. Studies also show that hypothalamic CPT1 activity also controls hormonal feedback. We hypothesis that hypothalamic carnitine metabolism represents a key molecular target that can concurrently integrate nutrient and hormonal information, which is critical to maintain energy homeostasis. We also suggest this is relevant to broader neuroendocrine research as it predicts that hormonal signaling in the brain varies depending on current nutrient status. Indeed, the metabolic action of ghrelin, leptin or insulin

  18. Effect of hypothalamic electrical stimulation on protein synthesis in organs of adult and old rats

    SciTech Connect

    Frol'kis, V.V.; Muradyan, K.K.; Rushkevich, Yu.E.; Mozzhukhina, T.G.; Khilobok, I.Yu.; Gol'dshtein, N.B.

    1986-12-01

    Age differences in hypothalamic regulation of total protein synthesis in different organs and also of liver chromatin proteins were compared in this investigation. Rats were used in the experiments and the intensity of protein synthesis was judged from the relative specific radioactivity which was determined as the ratio of the specific radioactivities of acid-insoluble and acid-soluble materials, separated by means of nitrocellulose membrane filters. Protein was determined by two-wave spectrophotometry and the radioactivity of all samples was measured on a Mark III radio spectrometer. The investigations showed that hypothalmic electrical stimulation causes a marked increase in /sup 3/H-leucine incorporation into protein of active and inactive liver chromatin.

  19. Magnetic Resonance Imaging Features of Solitary Hypothalamitis.

    PubMed

    Zhang, Hua; Wang, Jing; Wu, Yue; Tang, Ying; Tao, Ran; Ye, Hongying; Yao, Zhenwei

    The study aimed to characterize magnetic resonance imaging (MRI) findings of solitary hypothalamitis and evaluate their clinical value in diagnosis. Magnetic resonance imaging scans, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), and contrast-enhanced T1-weighted sequences, of 8 biopsy-proven hypothalamitis lesions were retrospectively analyzed along with MRI features including size, shape, signal intensity, enhancement pattern, correlation with adjacent tissues, and changes in infundibular stalk and sella turcica. Of 8 patients, 5 were diagnosed with lymphoplasmacytic proliferative inflammation, 2 with Langerhans cell histocytosis, and 1 with Rosai-Dorfman disease. Solitary hypothalamitis predominantly demonstrated mild hypointensity/isointensity in T1WI and mild hyperintensity in T2-weighted imaging. In contrast-enhanced T1WI, all lesions showed heterogeneous but primarily peripheral enhancement patterns. Seven cases showed the polygon sign. In T1WI, the normal high signal intensity of neurohypophysis was absent from all patients, with no infundibular stalk thickening. Seven patients presented with optic chiasma edema, and 5 with edema-like changes along the optic tract (OTE), but most showed no visual impairment (n = 7). Magnetic resonance imaging, particularly postcontrast MRI, is the optimal modality for assessment of hypothalamic lesions. Peripheral enhancement with polygon sign and optic tract or chiasm edema without visual impairment are highly suggestive of hypothalamitis.

  20. Bardoxolone methyl prevents obesity and hypothalamic dysfunction.

    PubMed

    Camer, Danielle; Yu, Yinghua; Szabo, Alexander; Wang, Hongqin; Dinh, Chi H L; Huang, Xu-Feng

    2016-08-25

    High-fat (HF) diet-induced obesity is associated with hypothalamic leptin resistance and low grade chronic inflammation, which largely impairs the neuroregulation of negative energy balance. Neuroregulation of negative energy balance is largely controlled by the mediobasal and paraventricular nuclei regions of the hypothalamus via leptin signal transduction. Recently, a derivative of oleanolic acid, bardoxolone methyl (BM), has been shown to have anti-inflammatory effects. We tested the hypothesis that BM would prevent HF diet-induced obesity, hypothalamic leptin resistance, and inflammation in mice fed a HF diet. Oral administration of BM via drinking water (10 mg/kg daily) for 21 weeks significantly prevented an increase in body weight, energy intake, hyperleptinemia, and peripheral fat accumulation in mice fed a HF diet. Furthermore, BM treatment prevented HF diet-induced decreases in the anorexigenic effects of peripheral leptin administration. In the mediobasal and paraventricular nuclei regions of the hypothalamus, BM administration prevented HF diet-induced impairments of the downstream protein kinase b (Akt) pathway of hypothalamic leptin signalling. BM treatment also prevented an increase in inflammatory cytokines, tumour necrosis factor alpha (TNFα) and interleukin 6 (IL-6) in these two hypothalamic regions. These results identify a potential novel neuropharmacological application for BM in preventing HF diet-induced obesity, hypothalamic leptin resistance, and inflammation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  1. Hypothalamic dysfunction following whole-brain irradiation

    SciTech Connect

    Mechanick, J.I.; Hochberg, F.H.; LaRocque, A.

    1986-10-01

    The authors describe 15 cases with evidence of hypothalamic dysfunction 2 to 9 years following megavoltage whole-brain x-irradiation for primary glial neoplasm. The patients received 4000 to 5000 rads in 180- to 200-rad fractions. Dysfunction occurred in the absence of computerized tomography-delineated radiation necrosis or hypothalamic invasion by tumor, and antedated the onset of dementia. Fourteen patients displayed symptoms reflecting disturbances of personality, libido, thirst, appetite, or sleep. Hyperprolactinemia (with prolactin levels up to 70 ng/ml) was present in all of the nine patients so tested. Of seven patients tested with thyrotropin-releasing hormone, one demonstrated an abnormal pituitary gland response consistent with a hypothalamic disorder. Seven patients developed cognitive abnormalities. Computerized tomography scans performed a median of 4 years after tumor diagnosis revealed no hypothalamic tumor or diminished density of the hypothalamus. Cortical atrophy was present in 50% of cases and third ventricular dilatation in 58%. Hypothalamic dysfunction, heralded by endocrine, behavioral, and cognitive impairment, represents a common, subtle form of radiation damage.

  2. Neuroanatomy and physiology of the avian hypothalamic/pituitary axis: clinical aspects.

    PubMed

    Ritchie, Midge

    2014-01-01

    This article describes the anatomy of the avian hypothalamic/pituitary axis, the hypothalamic-pituitary-thyroid axis, the hypothalamic-pituitary-adrenal axis, the hypothalamic-pituitary-gonadal axis, the somatotrophic axis, and neurohypophysis.

  3. Leucine Supplementation Protects from Insulin Resistance by Regulating Adiposity Levels

    PubMed Central

    Binder, Elke; Bermúdez-Silva, Francisco J.; André, Caroline; Elie, Melissa; Romero-Zerbo, Silvana Y.; Leste-Lasserre, Thierry; Belluomo, llaria; Duchampt, Adeline; Clark, Samantha; Aubert, Agnes; Mezzullo, Marco; Fanelli, Flaminia; Pagotto, Uberto; Layé, Sophie; Mithieux, Gilles; Cota, Daniela

    2013-01-01

    Background Leucine supplementation might have therapeutic potential in preventing diet-induced obesity and improving insulin sensitivity. However, the underlying mechanisms are at present unclear. Additionally, it is unclear whether leucine supplementation might be equally efficacious once obesity has developed. Methodology/Principal Findings Male C57BL/6J mice were fed chow or a high-fat diet (HFD), supplemented or not with leucine for 17 weeks. Another group of HFD-fed mice (HFD-pairfat group) was food restricted in order to reach an adiposity level comparable to that of HFD-Leu mice. Finally, a third group of mice was exposed to HFD for 12 weeks before being chronically supplemented with leucine. Leucine supplementation in HFD-fed mice decreased body weight and fat mass by increasing energy expenditure, fatty acid oxidation and locomotor activity in vivo. The decreased adiposity in HFD-Leu mice was associated with increased expression of uncoupling protein 3 (UCP-3) in the brown adipose tissue, better insulin sensitivity, increased intestinal gluconeogenesis and preservation of islets of Langerhans histomorphology and function. HFD-pairfat mice had a comparable improvement in insulin sensitivity, without changes in islets physiology or intestinal gluconeogenesis. Remarkably, both HFD-Leu and HFD-pairfat mice had decreased hepatic lipid content, which likely helped improve insulin sensitivity. In contrast, when leucine was supplemented to already obese animals, no changes in body weight, body composition or glucose metabolism were observed. Conclusions/Significance These findings suggest that leucine improves insulin sensitivity in HFD-fed mice by primarily decreasing adiposity, rather than directly acting on peripheral target organs. However, beneficial effects of leucine on intestinal gluconeogenesis and islets of Langerhans's physiology might help prevent type 2 diabetes development. Differently, metabolic benefit of leucine supplementation is lacking in

  4. Downregulation of AMPK Accompanies Leucine- and Glucose-Induced Increases in Protein Synthesis and Insulin Resistance in Rat Skeletal Muscle

    PubMed Central

    Saha, Asish K.; Xu, X. Julia; Lawson, Ebony; Deoliveira, Rosangela; Brandon, Amanda E.; Kraegen, Edward W.; Ruderman, Neil B.

    2010-01-01

    OBJECTIVE Branched-chain amino acids, such as leucine and glucose, stimulate protein synthesis and increase the phosphorylation and activity of the mammalian target of rapamycin (mTOR) and its downstream target p70S6 kinase (p70S6K). We examined in skeletal muscle whether the effects of leucine and glucose on these parameters and on insulin resistance are mediated by the fuel-sensing enzyme AMP-activated protein kinase (AMPK). RESEARCH DESIGN AND METHODS Rat extensor digitorum longus (EDL) muscle was incubated with different concentrations of leucine and glucose with or without AMPK activators. Muscle obtained from glucose-infused rats was also used as a model. RESULTS In the EDL, incubation with 100 or 200 μmol/l leucine versus no added leucine suppressed the activity of the α2 isoform of AMPK by 50 and 70%, respectively, and caused concentration-dependent increases in protein synthesis and mTOR and p70S6K phosphorylation. Very similar changes were observed in EDL incubated with 5.5 or 25 mmol/l versus no added glucose and in muscle of rats infused with glucose in vivo. Incubation of the EDL with the higher concentrations of both leucine and glucose also caused insulin resistance, reflected by a decrease in insulin-stimulated Akt phosphorylation. Coincubation with the AMPK activators AICAR and α-lipoic acid substantially prevented all of those changes and increased the phosphorylation of specific sites of mTOR inhibitors raptor and tuberous sclerosis complex 2 (TSC2). In contrast, decreases in AMPK activity induced by leucine and glucose were not associated with a decrease in raptor or TSC2 phosphorylation. CONCLUSIONS The results indicate that both leucine and glucose modulate protein synthesis and mTOR/p70S6 and insulin signaling in skeletal muscle by a common mechanism. They also suggest that the effects of both molecules are associated with a decrease in AMPK activity and that AMPK activation prevents them. PMID:20682696

  5. Transcriptional profiling of fetal hypothalamic TRH neurons

    PubMed Central

    2011-01-01

    Background During murine hypothalamic development, different neuroendocrine cell phenotypes are generated in overlapping periods; this suggests that cell-type specific developmental programs operate to achieve complete maturation. A balance between programs that include cell proliferation, cell cycle withdrawal as well as epigenetic regulation of gene expression characterizes neurogenesis. Thyrotropin releasing hormone (TRH) is a peptide that regulates energy homeostasis and autonomic responses. To better understand the molecular mechanisms underlying TRH neuron development, we performed a genome wide study of its transcriptome during fetal hypothalamic development. Results In primary cultures, TRH cells constitute 2% of the total fetal hypothalamic cell population. To purify these cells, we took advantage of the fact that the segment spanning -774 to +84 bp of the Trh gene regulatory region confers specific expression of the green fluorescent protein (GFP) in the TRH cells. Transfected TRH cells were purified by fluorescence activated cell sorting, various cell preparations pooled, and their transcriptome compared to that of GFP- hypothalamic cells. TRH cells undergoing the terminal phase of differentiation, expressed genes implicated in protein biosynthesis, intracellular signaling and transcriptional control. Among the transcription-associated transcripts, we identified the transcription factors Klf4, Klf10 and Atf3, which were previously uncharacterized within the hypothalamus. Conclusion To our knowledge, this is one of the first reports identifying transcripts with a potentially important role during the development of a specific hypothalamic neuronal phenotype. This genome-scale study forms a rational foundation for identifying genes that might participate in the development and function of hypothalamic TRH neurons. PMID:21569245

  6. Hypothalamic mTOR: the rookie energy sensor.

    PubMed

    Martínez de Morentin, P B; Martinez-Sanchez, N; Roa, J; Ferno, J; Nogueiras, R; Tena-Sempere, M; Dieguez, C; Lopez, M

    2014-01-01

    Optimal cellular function and therefore organism's survival is determined by the sensitive and accurate convergence of energy and nutrient abundance to cell growth and division. Among other factors, this integration is coupled by the target of rapamycin (TOR) pathway, which is able to sense nutrient, energy and oxygen availability and also growth factor signaling. Indeed, TOR signaling regulates cell energy homeostasis by coordinating anabolic and catabolic processes for survival. TOR, named mTOR in mammals, is a conserved serine/threonine kinase that exists in two different complexes, mTORC1 and mTORC2. Recently, studies are suggesting that alterations of those complexes promote disease and disrupted phenotypes, such as aging, obesity and related disorders and even cancer. The evidences linking mTOR to energy and metabolic homeostasis included the following. At central level mTOR regulates food intake and body weight being involved in the mechanism by which signals such as leptin and ghrelin exert its effects. At peripheral level it influences adipogenesis and lipogenesis in different tissues including the liver. Noteworthy chronic nutritional activation of mTOR signaling has been implicated in the development of beta cell mass expansion and on insulin resistance. Understanding of mTOR and other molecular switches, such as AMP-activated protein kinase (AMPK), as well as their interrelationship is crucial to know how organisms maintain optimal homeostasis. This review summarizes the role of hypothalamic TOR complex in cellular energy sensing, evidenced in the last years, focusing on the metabolic pathways where it is involved and the importance of this metabolic sensor in cellular and whole body energy management. Understanding the exact role of hypothalamic mTOR may provide new cues for therapeutic intervention in diseases.

  7. Life-extending dietary restriction and ovariectomy each increase leucine oxidation and alter leucine allocation in grasshoppers.

    PubMed

    Hatle, John D; Awan, Ayesha; Nicholas, Justin; Koch, Ryan; Vokrri, Julie R; McCue, Marshall D; Williams, Caroline M; Davidowitz, Goggy; Hahn, Daniel A

    2017-10-01

    Reduced reproduction and dietary restriction each extend lifespan in many animal models, but possible contributions of nutrient oxidation and allocation are largely unknown. Ovariectomy and eating 70% of ad libitum-feeding each extend lifespan in lubber grasshoppers. When feeding levels between the two groups are matched, ovariectomy increases fat and protein storage while dietary restriction reduces fat storage. Because of these disparities in nutrient investment, metabolism may differ between these two life-extending treatments. Therefore, we examined the allocation and organismal oxidation of one representative of each macronutrient class: leucine, oleic acid, and glucose. Ovariectomy and dietary restriction each increased oxidation of dietary leucine. Dietary leucine may play a special role in aging because amino acids stimulate cellular growth. Speeding oxidation of leucine may attenuate cellular growth. Allocation of leucine to muscle was the clearest difference between ovariectomy and dietary restriction in this study. Ovariectomy reduced allocation of leucine to femur muscle, whereas dietary restriction increased allocation of leucine to femur muscle. This allocation likely corresponds to muscle maintenance for locomotion, suggesting dietary restriction increases support for locomotion, perhaps to search for food. Last, ovariectomy decreased oxidation of dietary oleic acid and glucose, perhaps to save them for storage, but the site of storage is unclear. This study suggests that the oxidation of branched-chain amino acids may be an underappreciated mechanism underlying lifespan extension. Copyright © 2017. Published by Elsevier Inc.

  8. Psychogenic gelastic seizures in a patient with hypothalamic hamartoma.

    PubMed

    Scarella, Timothy; Macken, Michael P; Gerard, Elizabeth; Schuele, Stephan U

    2012-06-01

    Gelastic seizures are classically associated with hypothalamic hamartoma. The most effective treatment for gelastic epilepsy is surgery, although confirming that a hypothalamic hamartoma is an epileptic lesion prior to surgical intervention is challenging. Here, we report the case of a patient with a hypothalamic hamartoma who was diagnosed with psychogenic non-epileptic gelastic seizures using video-EEG monitoring. [Published with video sequences].

  9. The organization of the hypothalamic pathways mediating affective defense behavior in the cat.

    PubMed

    Fuchs, S A; Edinger, H M; Siegel, A

    1985-03-18

    The purpose of this study was to describe the hypothalamic pathways which mediate affective defense in the cat utilizing the methods of [14C]2-deoxyglucose (2-DG) and [3H]leucine radioautography in concert with the technique of electrical brain stimulation. The feline affective defense response, characterized by pupillary dilatation, piloerection, ear retraction, hissing, growling and striking with the forepaws, was elicited consistently by stimulation of sites within the ventromedial hypothalamus and anterior aspect of the medial hypothalamus. In one series of experiments, 2-DG autoradiography was employed to describe the brain regions activated following stimulation of sites in the region of the ventromedial hypothalamus from which affective defense had been elicited. Ventromedial hypothalamic stimulation produced activation primarily in forebrain regions situated rostral to the level of the stimulating electrode. These structures included principally the anteromedial hypothalamus and medial preoptic area, as well as the bed nuclei of the stria terminalis and anterior commissure, diagonal band and lateral septal area. The caudal extent of activation included only the dorsal and perifornical hypothalamus at the level of the stimulation site. In a second series of experiments, affective defense sites in the anteromedial hypothalamus were stimulated and the regional distribution of 2-DG label was identified. In contrast to the results obtained from ventromedial hypothalamic stimulation, these experiments revealed a marked descending distribution of label within the posterior hypothalamus, midbrain central gray and ventral tegmental area. Results obtained from studies in which tritiated amino acids were injected into affective defense sites in both the ventromedial nucleus and anteromedial hypothalamus confirmed the general findings observed with 2-DG autoradiography. From these observations, we have concluded that the organization of the pathway mediating affective

  10. Photoinactivation and carbethoxylation of leucine aminopeptidase.

    PubMed

    Ludewig, M; Frohne, M; Marquardt, I; Hanson, H

    1975-05-01

    In the present paper the reactivity of histidyl residues of leucine aminopeptidase from bovine eye lens was studied by dye-sensitized photooxidation and by carbethoxylation of the enzyme protein using diethylpyrocarbonate. Of all the different amino acids modified by photooxidation only histidine is connected with the enzymic acticity, whereas tyrosine seems to be involved in structure stabilization. By changing the pH and varying the effectors (Mg2+ and/or dodecylsulfate) of the reaction mixture a different number of histidyl residues of the enzyme protein is caused to react with diethylpyrocarbonate. No secondary reactions with tyrosyl or tryptophyl residues could be observed by spectrophotometric investigations. The enzyme modified by one of the above-mentioned methods shows changes in the capacity of Mn2+ binding measured by autoradiography as well as in the degree of enhancement of enzymic activity by Mn2+ or Mg2+ ions. Of the 48 histidyl residues of the enzyme (Mr = 326000) up to 2 histidyl residues per subunit (Mr = 54000) may be involved in Mn2+ or Mg2+ binding and up to 4 histidyl residues have a strong influence on Zn2+ binding.

  11. Hyperprolactinemia from radiation-induced hypothalamic hypopituitarism

    SciTech Connect

    Corkill, G.; Hanson, F.W.; Gold, E.M.; White, V.A.

    1980-01-01

    In 1975 Samaan et al., described the effects of radiation damage of the hypothalamus in 15 patients with head and neck cancer. Shalet et al., in 1977 described endocrine morbidity in adults who as children had been irradiated for brain tumors. This report describes instances of hyperprolactinemia and associated hypothalamic, pituitary, and thyroid dysfunction following irradiation of a young adult female for brain neoplasia.

  12. Gelastic seizures: not always hypothalamic hamartoma.

    PubMed

    Cheung, Christina S; Parrent, Andrew G; Burneo, Jorge G

    2007-12-01

    Gelastic seizures are often associated with hypothalamic hamartomas. However, focal cortical dysplasias can also cause "laughing seizures", and such cases can be difficult to localize with EEG. This case report presents a 29-year-old woman who was successfully rendered free of gelastic seizures after resection of a frontal cortical dysplasia, localized through MRI and SPECT imaging.[Published with video sequences].

  13. Flatfish metamorphosis: a hypothalamic independent process?

    PubMed

    Campinho, Marco A; Silva, Nadia; Roman-Padilla, Javier; Ponce, Marian; Manchado, Manuel; Power, Deborah M

    2015-03-15

    Anuran and flatfish metamorphosis are tightly regulated by thyroid hormones that are the necessary and sufficient factors that drive this developmental event. In the present study whole mount in situ hybridization (WISH) and quantitative PCR in sole are used to explore the central regulation of flatfish metamorphosis. Central regulation of the thyroid in vertebrates is mediated by the hypothalamus-pituitary-thyroid (HPT) axis. Teleosts diverge from other vertebrates as hypothalamic regulation in the HPT axis is proposed to be through hypothalamic inhibition although the regulatory factor remains enigmatic. The dynamics of the HPT axis during sole metamorphosis revealed integration between the activity of the thyrotrophes in the pituitary and the thyroid follicles. No evidence was found supporting a role for thyroid releasing hormone (trh) or corticotrophin releasing hormone (crh) in hypothalamic control of TH production during sole metamorphosis. Intriguingly the results of the present study suggest that neither hypothalamic trh nor crh expression changes during sole metamorphosis and raises questions about the role of these factors and the hypothalamus in regulation of thyrotrophs. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  14. Immunoglobulin therapy in idiopathic hypothalamic dysfunction.

    PubMed

    Huppke, Peter; Heise, Alexander; Rostasy, Kevin; Huppke, Brenda; Gärtner, Jutta

    2009-09-01

    Idiopathic hypothalamic dysfunction is a rare disorder presenting at age 3-7 years. Severe hypothalamic and brainstem dysfunction leads to death in 25% of patients. The disease is presumed to be autoimmune, or in some cases paraneoplastic. No successful treatment has been reported. Patient V. developed hyperphagia, hypersomnia, and extreme aggression at age 7 years, accompanied by episodes of hyperthermia, hypothermia, sinus bradycardia, hypernatremia, hyponatremia, persistent hyperprolactinemia, hypothyroidism, and growth-hormone deficiency. At age 9 years, a diagnosis of idiopathic hypothalamic dysfunction was rendered, and immunoglobulin therapy was commenced. Nine courses of immunoglobulins, at a dose of 2 g/kg every 4 weeks, were administered. Reproducible improvements in behavior and no further episodes of hyponatremia or hypernatremia and sinus bradycardia were evident. The endocrinologic abnormalities and poor thermoregulation remained. Administration of immunoglobulins during late stages of idiopathic hypothalamic dysfunction led to improvement in some but not all signs. Assuming an autoimmune basis for this disorder, treatment during early stages of disease should be more effective. To facilitate such early treatment, increased awareness of this disorder is necessary, to allow for early diagnosis.

  15. Role of developmental factors in hypothalamic function

    PubMed Central

    Biran, Jakob; Tahor, Maayan; Wircer, Einav; Levkowitz, Gil

    2015-01-01

    The hypothalamus is a brain region which regulates homeostasis by mediating endocrine, autonomic and behavioral functions. It is comprised of several nuclei containing distinct neuronal populations producing neuropeptides and neurotransmitters that regulate fundamental body functions including temperature and metabolic rate, thirst and hunger, sexual behavior and reproduction, circadian rhythm, and emotional responses. The identity, number and connectivity of these neuronal populations are established during the organism’s development and are of crucial importance for normal hypothalamic function. Studies have suggested that developmental abnormalities in specific hypothalamic circuits can lead to obesity, sleep disorders, anxiety, depression and autism. At the molecular level, the development of the hypothalamus is regulated by transcription factors (TF), secreted growth factors, neuropeptides and their receptors. Recent studies in zebrafish and mouse have demonstrated that some of these molecules maintain their expression in the adult brain and subsequently play a role in the physiological functions that are regulated by hypothalamic neurons. Here, we summarize the involvement of some of the key developmental factors in hypothalamic development and function by focusing on the mouse and zebrafish genetic model organisms. PMID:25954163

  16. Hypothalamic inflammation and gliosis in obesity

    PubMed Central

    Dorfman, Mauricio D.; Thaler, Joshua P.

    2015-01-01

    Structured Abstract Purpose of review Hypothalamic inflammation and gliosis are recently discovered mechanisms that may contribute to obesity pathogenesis. Current research in this area suggests that investigation of these CNS responses may provide opportunities to develop new weight loss treatments. Recent findings In rodents, hypothalamic inflammation and gliosis occur rapidly with high-fat diet consumption prior to significant weight gain. In addition, sensitivity or resistance to diet-induced obesity in rodents generally correlates with the presence or absence of hypothalamic inflammation and reactive gliosis (brain response to injury). Moreover, functional interventions that increase or decrease inflammation in neurons and glia correspondingly alter diet-associated weight gain. However, some conflicting data have recently emerged that question the contribution of hypothalamic inflammation to obesity pathogenesis. However, several studies have detected gliosis and disrupted connectivity in obese humans, highlighting the potential translational importance of this mechanism. Summary There is growing evidence that obesity is associated with brain inflammation in humans, particularly in the hypothalamus where its presence may disrupt body weight control and glucose homeostasis. More work is needed to determine whether this response is common in human obesity and to what extent it can be manipulated for therapeutic benefit. PMID:26192704

  17. Efficacy and Safety of Leucine Supplementation in the Elderly.

    PubMed

    Borack, Michael S; Volpi, Elena

    2016-12-01

    Leucine supplementation has grown in popularity due to the discovery of its anabolic effects on cell signaling and protein synthesis in muscle. The current recommendation is a minimum intake of 55 mg ⋅ kg(-1)(.) d(-1) Leucine acutely stimulates skeletal muscle anabolism and can overcome the anabolic resistance of aging. The value of chronic leucine ingestion for muscle growth is still unclear. Most of the research into leucine consumption has focused on efficacy. To our knowledge, very few studies have sought to determine the maximum safe level of intake. Limited evidence suggests that intakes of ≤1250 mg ⋅ kg(-1)(.) d(-1) do not appear to have any health consequences other than short-term elevated plasma ammonia concentrations. Similarly, no adverse events have been reported for the leucine metabolite β-hydroxy-β-methylbutyrate (HMB), although no studies have tested HMB toxicity in humans. Therefore, future research is needed to evaluate leucine and HMB toxicity in the elderly and in specific health conditions. © 2016 American Society for Nutrition.

  18. Leucine supplementation improves regeneration of skeletal muscles from old rats.

    PubMed

    Pereira, Marcelo G; Silva, Meiricris T; da Cunha, Fernanda M; Moriscot, Anselmo S; Aoki, Marcelo S; Miyabara, Elen H

    2015-12-01

    The decreased regenerative capacity of old skeletal muscles involves disrupted turnover of proteins. This study investigated whether leucine supplementation in old rats could improve muscle regenerative capacity. Young and old male Wistar rats were supplemented with leucine; then, the muscles were cryolesioned and examined after 3 and 10 days. Leucine supplementation attenuated the decrease in the expression of eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1) and eukaryotic translation initiation factor 4E (eIF4E) in young and old muscles on day 3 post-injury and promoted an increase in the cross-sectional area of regenerating myofibers from both young and old soleus muscles on day 10 post-injury. This supplementation decreased the levels of ubiquitinated proteins and increased the proteasome activity in young regenerating muscles, but the opposite effect was observed in old regenerating muscles. Moreover, leucine decreased the inflammation area and induced an increase in the number of proliferating satellite cells in both young and old muscles. Our results suggest that leucine supplementation improves the regeneration of skeletal muscles from old rats, through the preservation of certain biological responses upon leucine supplementation. Such responses comprise the decrease in the inflammation area, increase in the number of proliferating satellite cells and size of regenerating myofibers, combined with the modulation of components of the phosphoinositide 3-kinase/Akt-protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway and ubiquitin-proteasome system.

  19. Fetoplacental deamination and decarboxylation of leucine

    SciTech Connect

    Loy, G.L.; Quick, A.N. Jr.; Hay, W.W. Jr.; Meschia, G.; Battaglia, F.C.; Fennessey, P.V. )

    1990-10-01

    Fetal and placental metabolism of leucine (Leu) and ketoisocaproic acid (KIC) were studied in seven fetal lambs at 132 +/- 1.3-days gestation. Fetal infusions of (1-13C)Leu, (1-14C)Leu, and antipyrine were carried out for 4 h. Uterine and umbilical blood flows were measured using the antipyrine steady-state diffusion technique. Leu and KIC concentrations, (14C)Leu-specific activities, 14CO2, (13C)Leu, and (13C)KIC enrichment (mole percent enrichment) were measured in the maternal artery, uterine vein, and umbilical artery and vein to calculate net fluxes of tracee and tracer molecules between fetus and placenta and between the uteroplacenta and the maternal circulation. There were net Leu and KIC fluxes into the fetus from the placenta with the KIC flux equal to approximately 19% of the combined Leu plus KIC flux. In addition, there was a net KIC flux into the uterine circulation. The fraction of infused tracer Leu escaping the placenta into the mother was small (approximately 6%). By contrast, there was a rapid exchange of tracer Leu carbon between placenta and fetus resulting in a significant flux of labeled KIC from placenta to fetus. Approximately 20% of the infused tracer carbon was converted to CO2 within the fetus. This rate of conversion was greater than 80% of the total fetoplacental conversion rate and significantly higher than the flux of KIC tracer carbon from placenta to fetus. Fetal KIC decarboxylation rate, calculated from the fetal KIC enrichment data, was 2.83 +/- 0.40 mumol.min-1.kg fetus-1 and approximately 60% of the combined net Leu and KIC flux into the fetus from the placenta.

  20. Effect of exercise training on leucine oxidation

    SciTech Connect

    Hendrix, M.K.; Layman, D.K.

    1986-03-01

    Oxidation of the BCAA leucine is increased during a bout of exhaustive exercise. The purpose of this study was to determine the effects of exercise training on leu oxidation during aerobic exercise. Female Sprague-Dawley rats were fed a commercial diet ad lib and divided into sedentary and two trained groups. Animals were trained to run on a treadmill with a 10/sup 0/ incline at 28 m/min for 5 wks for either 50 or 120 min/day. There were no differences in food intake or body weight. After a 12 hr fast, animals were run for 50 or 120 min and changes in leu catabolism determined by measurement of in vivo leu oxidation and activity of branched chain keto acid dehydrogenase (BCKAD). For measurement of leu oxidation, rats were injected IP with 4 ..mu..Ci 1-/sup 14/C-leu during the last 15 min of exercise, placed in glass metabolic chambers, and /sup 14/CO/sub 2/ collected in 1 N NaOH for 30 min periods. Leu oxidation was increased by 40% after 50 min of exercise and by 79% after 120 min of exercise. Five weeks of training reduced the rate of leu oxidation during an exercise bout. The activity of the BCKAD was not increased in the trained animals after either 50 or 120 min of exercise. These data indicate that the rate of leu oxidation during exercises is dependent on the duration of the exercise and that training will reduce the magnitude of this effect.

  1. Photodissociation spectroscopy of protonated leucine enkephalin.

    PubMed

    Herburger, Andreas; van der Linde, Christian; Beyer, Martin K

    2017-02-24

    Protonated leucine enkephalin (YGGFL) was studied by ultraviolet photodissociation (UVPD) from 225 to 300 nm utilizing an optical parametric oscillator tunable wavelength laser system (OPO). Fragments were identified by absolute mass measurement in a 9.4 T Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). Bond cleavage was preferred in the vicinity of the two aromatic residues, resulting in high ion abundances for a4, a1, b3, y2 and y1 fragments. a, b and y ions dominated the mass spectrum, and full sequence coverage was achieved for those types. Photodissociation was most effective at the short wavelength end of the studied range, which is assigned to the onset of the La π-π* transition of the tyrosine chromophore, but worked well also at the Lb π-π* chromophore absorption maxima in the 35 000-39 000 cm(-1) region. Several side-chain and internal fragments were observed. H atom loss is observed only above 41 000 cm(-1), consistent with the requirement of a curve crossing to a repulsive (1)πσ* state. It is suggested that the photochemically generated mobile H atom plays a role in further backbone cleavages, similar to the mechanism for electron capture dissociation. The b4 fragment is most intense at the Lb chromophore absorptions, undergoing additional fragmentation at higher photon energies. The high resolution of the FT-ICR MS revealed that out of all x and z-type fragments only x3 and x4 were formed, with low intensity. Other previously reported x- and z-fragments were re-assigned to internal fragments, based on exact mass measurement.

  2. GCN2 contributes to mTORC1 inhibition by leucine deprivation through an ATF4 independent mechanism

    PubMed Central

    Averous, Julien; Lambert-Langlais, Sarah; Mesclon, Florent; Carraro, Valérie; Parry, Laurent; Jousse, Céline; Bruhat, Alain; Maurin, Anne-Catherine; Pierre, Philippe; Proud, Christopher G.; Fafournoux, Pierre

    2016-01-01

    It is well known that the GCN2 and mTORC1 signaling pathways are regulated by amino acids and share common functions, in particular the control of translation. The regulation of GCN2 activity by amino acid availability relies on the capacity of GCN2 to sense the increased levels of uncharged tRNAs upon amino acid scarcity. In contrast, despite recent progress in the understanding of the regulation of mTORC1 by amino acids, key aspects of this process remain unsolved. In particular, while leucine is well known to be a potent regulator of mTORC1, the mechanisms by which this amino acid is sensed and control mTORC1 activity are not well defined. Our data establish that GCN2 is involved in the inhibition of mTORC1 upon leucine or arginine deprivation. However, the activation of GCN2 alone is not sufficient to inhibit mTORC1 activity, indicating that leucine and arginine exert regulation via additional mechanisms. While the mechanism by which GCN2 contributes to the initial step of mTORC1 inhibition involves the phosphorylation of eIF2α, we show that it is independent of the downstream transcription factor ATF4. These data point to a novel role for GCN2 and phosphorylation of eIF2α in the control of mTORC1 by certain amino acids. PMID:27297692

  3. Understanding how discrete populations of hypothalamic neurons orchestrate complicated behavioral states

    PubMed Central

    Graebner, Allison K.; Iyer, Manasi; Carter, Matthew E.

    2015-01-01

    A major question in systems neuroscience is how a single population of neurons can interact with the rest of the brain to orchestrate complex behavioral states. The hypothalamus contains many such discrete neuronal populations that individually regulate arousal, feeding, and drinking. For example, hypothalamic neurons that express hypocretin (Hcrt) neuropeptides can sense homeostatic and metabolic factors affecting wakefulness and orchestrate organismal arousal. Neurons that express agouti-related protein (AgRP) can sense the metabolic needs of the body and orchestrate a state of hunger. The organum vasculosum of the lamina terminalis (OVLT) can detect the hypertonicity of blood and orchestrate a state of thirst. Each hypothalamic population is sufficient to generate complicated behavioral states through the combined efforts of distinct efferent projections. The principal challenge to understanding these brain systems is therefore to determine the individual roles of each downstream projection for each behavioral state. In recent years, the development and application of temporally precise, genetically encoded tools has greatly improved our understanding of the structure and function of these neural systems. This review will survey recent advances in our understanding of how these individual hypothalamic populations can orchestrate complicated behavioral states due to the combined efforts of individual downstream projections. PMID:26300745

  4. Leucine Stimulates Insulin Secretion via Down-regulation of Surface Expression of Adrenergic α2A Receptor through the mTOR (Mammalian Target of Rapamycin) Pathway

    PubMed Central

    Yang, Jun; Dolinger, Michael; Ritaccio, Gabrielle; Mazurkiewicz, Joseph; Conti, David; Zhu, Xinjun; Huang, Yunfei

    2012-01-01

    The amino acid leucine is a potent secretagogue, capable of inducing insulin secretion. It also plays an important role in the regulation of mTOR activity, therefore, providing impetus to investigate if a leucine-sensing mechanism in the mTOR pathway is involved in insulin secretion. We found that leucine-induced insulin secretion was inhibited by both the mTOR inhibitor rapamycin as well as the adrenergic α2 receptor agonist clonidine. We also demonstrated that leucine down-regulated the surface expression of adrenergic α2A receptor via activation of the mTOR pathway. The leucine stimulatory effect on insulin secretion was attenuated in diabetic Goto-Kakizaki rats that overexpress adrenergic α2A receptors, confirming the role of leucine in insulin secretion. Thus, our data demonstrate that leucine regulates insulin secretion by modulating adrenergic α2 receptors through the mTOR pathway. The role of the mTOR pathway in metabolic homeostasis led us to a second important finding in this study; retrospective analysis of clinical data showed that co-administration of rapamycin and clonidine was associated with an increased incidence of new-onset diabetes in renal transplantation patients over those receiving rapamycin alone. We believe that inhibition of mTOR by rapamycin along with activation of adrenergic α2 receptors by clonidine represents a double-hit to pancreatic islets that synergistically disturbs glucose homeostasis. This new insight may have important implications for the clinical management of renal transplant patients. PMID:22645144

  5. L-Leucine and NO-mediated cardiovascular function.

    PubMed

    Yang, Ying; Wu, Zhenlong; Meininger, Cynthia J; Wu, Guoyao

    2015-03-01

    Reduced availability of nitric oxide (NO) in the vasculature is a major factor contributing to the impaired action of insulin on blood flow and, therefore, insulin resistance in obese and diabetic subjects. Available evidence shows that vascular insulin resistance plays an important role in the pathogenesis of cardiovascular disease, the leading cause of death in developed nations. Interestingly, increased concentrations of L-leucine in the plasma occur in obese humans and other animals with vascular dysfunction. Among branched-chain amino acids, L-leucine is unique in inhibiting NO synthesis from L-arginine in endothelial cells and may modulate cardiovascular homeostasis in insulin resistance. Results of recent studies indicate that L-leucine is an activator of glutamine:fructose-6-phosphate aminotransferase (GFAT), which is the first and a rate-controlling enzyme in the synthesis of glucosamine (an inhibitor of endothelial NO synthesis). Through stimulating the mammalian target of rapamycin signaling pathway and thus protein synthesis, L-leucine may enhance GFAT protein expression, thereby inhibiting NO synthesis in endothelial cells. We propose that reducing circulating levels of L-leucine or endothelial GFAT activity may provide a potentially novel strategy for preventing and/or treating cardiovascular disease in obese and diabetic subjects. Such means may include dietary supplementation with either α-ketoglutarate to enhance the catabolism of L-leucine in the small intestine and other tissues or with N-ethyl-L-glutamine to inhibit GFAT activity in endothelial cells. Preventing leucine-induced activation of GFAT by nutritional supplements or pharmaceutical drugs may contribute to improved cardiovascular function by enhancing vascular NO synthesis.

  6. Leucine markedly regulates pancreatic exocrine secretion in goats.

    PubMed

    Yu, Z P; Xu, M; Liu, K; Yao, J H; Yu, H X; Wang, F

    2014-02-01

    Four goats (30.1 ± 1.3 kg) with common bile duct re-entrant catheter and duodenal catheter were used to evaluate the effects of duodenal leucine infusion on pancreatic exocrine secretion and plasma parameters with two 4 × 4 Latin square design experiments. In the long-term infusion experiment, goats were fed twice daily [700 g/day, dry matter (DM) basis] at 8:00 and 18:00 hours and were duodenally infused with 0, 3, 6, 9 g/day leucine for 14 days. Pancreatic juice and jugular blood samples were collected over 1-h intervals for 6 h daily from d 11 to 14 days to encompass a 24-h day. In the short-term experiment, goats were infused leucine for 10 h continuously at the same infusion rate with Experiment 1 after feed deprivation for 24 h repeated every 10 days. Pancreatic juice and blood samples were collected at 0, 1, 2, 4, 6, 8 and 10 h of infusion. The results showed that the long-term leucine infusion did not affect pancreatic juice secretion, protein output, trypsin and lipase secretion and plasma insulin concentration, but linearly increased α-amylase secretion. No changes in pancreatic protein and lipase secretion were observed in the short-term infusion. Pancreatic juice and α-amylase secretion responded quadratically, with the greatest values observed in the 3 and 6 g/day leucine respectively. Trypsin secretion linearly decreased, while plasma insulin concentration increased linearly with increased leucine infusion. The results demonstrated that duodenal leucine infusion dose and time dependently regulated pancreatic enzyme secretion not associated with the change in plasma insulin concentration.

  7. Perinatal nutrition programs the hypothalamic melanocortin system in offspring.

    PubMed

    Wattez, J-S; Delahaye, F; Lukaszewski, M-A; Risold, P-Y; Eberlé, D; Vieau, D; Breton, C

    2013-12-01

    Epidemiological studies initially suggested that maternal undernutrition leading to low birth weight may predispose for long-lasting energy balance disorders. High birth weight due to maternal obesity or diabetes, inappropriate early postnatal nutrition, and rapid catch-up growth, may also sensitize to increased risk of obesity. As stated by the Developmental Origin of Health and Disease concept, the perinatal perturbation of fetus/neonate nutrient supply might be a crucial determinant of individual programming of body weight set-point. The hypothalamic melanocortin system composed of the melanocortin receptor 4, its agonist α-melanin-stimulating hormone (α-MSH), and its antagonist agouti-related protein (AgRP) is considered as the main central anorexigenic pathway controlling energy homeostasis. Studies in numerous animal models demonstrated that this system is a prime target of developmental programming by maternal nutritional manipulation. In rodents, the perinatal period of life corresponds largely to the period of brain maturation (i. e., melanocortin neuronal differentiation and development of their neural projections). In contrast, these phenomena essentially take place before birth in bigger mammals. Despite these different developmental time windows, altricial and precocial species share several common offspring programming mechanisms. Offspring from malnourished dams present a hypothalamic melanocortin system with a series of alterations: impaired neurogenesis and neuronal functionality, disorganization of feeding pathways, modified glucose sensing, and leptin/insulin resistance. Overall, these alterations may account for the long-lasting dysregulation of energy balance and obesity. Following maternal malnutrition, hormonal and epigenetic mechanisms might be responsible for melanocortin system programming in offspring. © Georg Thieme Verlag KG Stuttgart · New York.

  8. Microglia Dictate the Impact of Saturated Fat Consumption on Hypothalamic Inflammation and Neuronal Function

    PubMed Central

    Valdearcos, Martin; Robblee, Megan M.; Benjamin, Daniel I.; Nomura, Daniel K.; Xu, Allison W.; Koliwad, Suneil K.

    2014-01-01

    Diets rich in saturated fat produce inflammation, gliosis, and neuronal stress in the mediobasal hypothalamus (MBH). Here we show that microglia mediate this process and its functional impact. Although microglia and astrocytes accumulate in the MBH of mice fed a diet rich in saturated fatty acids (SFAs), only the microglia undergo inflammatory activation, along with a build-up of hypothalamic SFAs. Enteric gavage specifically with SFAs reproduces microglial activation and neuronal stress in the MBH, and SFA treatment activates murine microglia, but not astrocytes, in culture. Moreover, depleting microglia abrogates SFA-induced inflammation in hypothalamic slices. Remarkably, depleting microglia from the MBH of mice abolishes inflammation and neuronal stress induced by excess SFA consumption, and in this context, microglial depletion enhances leptin signaling and reduces food intake. We thus show that microglia sense SFAs and orchestrate an inflammatory process in the MBH that alters neuronal function when SFA consumption is high. PMID:25497089

  9. Fertility-Regulating Kiss1 Neurons Arise from Hypothalamic Pomc-Expressing Progenitors

    PubMed Central

    Sanz, Elisenda; Quintana, Albert; Deem, Jennifer D.; Steiner, Robert A.; Palmiter, Richard D.

    2015-01-01

    Hypothalamic neuronal populations are central regulators of energy homeostasis and reproductive function. However, the ontogeny of these critical hypothalamic neuronal populations is largely unknown. We developed a novel approach to examine the developmental pathways that link specific subtypes of neurons by combining embryonic and adult ribosome-tagging strategies in mice. This new method shows that Pomc-expressing precursors not only differentiate into discrete neuronal populations that mediate energy balance (POMC and AgRP neurons), but also into neurons critical for puberty onset and the regulation of reproductive function (Kiss1 neurons). These results demonstrate a developmental link between nutrient-sensing and reproductive neuropeptide synthesizing neuronal populations and suggest a potential pathway that could link maternal nutrition to reproductive development in the offspring. PMID:25855171

  10. Effect of hyperammonemia on leucine and protein metabolism in rats.

    PubMed

    Holecek, M; Sprongl, L; Tichý, M

    2000-10-01

    The cause of muscle wasting and decreased plasma levels of branched chain amino acids (BCAA), valine, leucine, and isoleucine in liver cirrhosis is obscure. Here we have evaluated the effect of hyperammonemia. Rats were infused with either an ammonium acetate/bicarbonate mixture, a sodium acetate/bicarbonate mixture, or saline for 320 minutes. The parameters of leucine and protein metabolism were evaluated in the whole body and in several tissues using a primed constant intravenous infusion of L-[1-14C]leucine. Ammonium infusion caused an increase in ammonia and glutamine levels in plasma, a decrease in BCAA and alanine in plasma and skeletal muscle, a significant decrease in whole-body proteolysis and protein synthesis, and an increase in leucine oxidized fraction. A significant decrease in protein synthesis after ammonium infusion was observed in skeletal muscle while a nonsignificant effect was observed in liver, gut, heart, spleen, and kidneys. We conclude that the decrease in plasma BCAA after ammonia infusion is associated with decreased proteolysis and increased leucine oxidized fraction.

  11. Developmental programming of hypothalamic neuroendocrine systems.

    PubMed

    Ralevski, Alexandra; Horvath, Tamas L

    2015-10-01

    There is increasing evidence to suggest that the perinatal environment may alter the developmental programming of hypothalamic neuroendocrine systems in a manner that predisposes offspring to the development of metabolic syndrome. Although it is unclear how these effects might be mediated, it has been shown that changes in neuroendocrine programing during critical periods of development, either via maternal metabolic programming or other factors, can alter a fetus's metabolic fate. This review summarizes the hypothalamic circuits that mediate energy homeostasis and discusses the various factors that may influence the development and functioning of these neural systems, as well as the possible cognitive impairments that may arise as a result of these metabolic influences. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Organisation of the human dorsomedial hypothalamic nucleus.

    PubMed

    Koutcherov, Yuri; Mai, Juergen K; Ashwell, Ken W; Paxinos, George

    2004-01-19

    This study used acetylcholinesterase (AChE) histochemistry to reveal the organization of the dorsomedial hypothalamic nucleus (DM) in the human. Topographically, the human DM is similar to DM in the monkey and rat. It is wedged between the paraventricular nucleus, dorsally, and the ventromedial nucleus, ventrally. Laterally, DM borders the lateral hypothalamic area while medially it approaches the 3rd ventricle. The AChE staining distinguished two subcompartments of the human DM: the larger diffuse and the smaller compact DM. The subcompartmental organization of the human DM appears homologous to that found in the monkey and less complex than that reported in rats. Understanding of the organization of DM creates meaningful anatomical reference for physiological and pharmacological studies in the human hypothalamus.

  13. Hypothalamic Survival Circuits: Blueprints for Purposive Behaviors

    PubMed Central

    Sternson, Scott M.

    2015-01-01

    Neural processes that direct an animal’s actions toward environmental goals are critical elements for understanding behavior. The hypothalamus is closely associated with motivated behaviors required for survival and reproduction. Intense feeding, drinking, aggressive, and sexual behaviors can be produced by a simple neuronal stimulus applied to discrete hypothalamic regions. What can these “evoked behaviors” teach us about the neural processes that determine behavioral intent and intensity? Small populations of neurons sufficient to evoke a complex motivated behavior may be used as entry points to identify circuits that energize and direct behavior to specific goals. Here, I review recent applications of molecular genetic, optogenetic, and pharmacogenetic approaches that overcome previous limitations for analyzing anatomically complex hypothalamic circuits and their interactions with the rest of the brain. These new tools have the potential to bridge the gaps between neurobiological and psychological thinking about the mechanisms of complex motivated behavior. PMID:23473313

  14. Gliotransmission and Brain Glucose Sensing

    PubMed Central

    Lanfray, Damien; Arthaud, Sébastien; Ouellet, Johanne; Compère, Vincent; Do Rego, Jean-Luc; Leprince, Jérôme; Lefranc, Benjamin; Castel, Hélène; Bouchard, Cynthia; Monge-Roffarello, Boris; Richard, Denis; Pelletier, Georges; Vaudry, Hubert; Tonon, Marie-Christine; Morin, Fabrice

    2013-01-01

    Hypothalamic glucose sensing is involved in the control of feeding behavior and peripheral glucose homeostasis, and glial cells are suggested to play an important role in this process. Diazepam-binding inhibitor (DBI) and its processing product the octadecaneuropeptide (ODN), collectively named endozepines, are secreted by astroglia, and ODN is a potent anorexigenic factor. Therefore, we investigated the involvement of endozepines in brain glucose sensing. First, we showed that intracerebroventricular administration of glucose in rats increases DBI expression in hypothalamic glial-like tanycytes. We then demonstrated that glucose stimulates endozepine secretion from hypothalamic explants. Feeding experiments indicate that the anorexigenic effect of central administration of glucose was blunted by coinjection of an ODN antagonist. Conversely, the hyperphagic response elicited by central glucoprivation was suppressed by an ODN agonist. The anorexigenic effects of centrally injected glucose or ODN agonist were suppressed by blockade of the melanocortin-3/4 receptors, suggesting that glucose sensing involves endozepinergic control of the melanocortin pathway. Finally, we found that brain endozepines modulate blood glucose levels, suggesting their involvement in a feedback loop controlling whole-body glucose homeostasis. Collectively, these data indicate that endozepines are a critical relay in brain glucose sensing and potentially new targets in treatment of metabolic disorders. PMID:23160530

  15. Hypothalamic NUCKS regulates peripheral glucose homoeostasis.

    PubMed

    Qiu, Beiying; Shi, Xiaohe; Zhou, Qiling; Chen, Hui Shan; Lim, Joy; Han, Weiping; Tergaonkar, Vinay

    2015-08-01

    Nuclear ubiquitous casein and cyclin-dependent kinase substrate (NUCKS) is highly expressed in the brain and peripheral metabolic organs, and regulates transcription of a number of genes involved in insulin signalling. Whole-body depletion of NUCKS (NKO) in mice leads to obesity, glucose intolerance and insulin resistance. However, a tissue-specific contribution of NUCKS to the observed phenotypes remains unknown. Considering the pivotal roles of insulin signalling in the brain, especially in the hypothalamus, we examined the functions of hypothalamic NUCKS in the regulation of peripheral glucose metabolism. Insulin signalling in the hypothalamus was impaired in the NKO mice when insulin was delivered through intracerebroventricular injection. To validate the hypothalamic specificity, we crossed transgenic mice expressing Cre-recombinase under the Nkx2.1 promoter with floxed NUCKS mice to generate mice with hypothalamus-specific deletion of NUCKS (HNKO). We fed the HNKO and littermate control mice with a normal chow diet (NCD) and a high-fat diet (HFD), and assessed glucose tolerance, insulin tolerance and metabolic parameters. HNKO mice showed mild glucose intolerance under an NCD, but exacerbated obesity and insulin resistance phenotypes under an HFD. In addition, NUCKS regulated levels of insulin receptor in the brain. Unlike HNKO mice, mice with immune-cell-specific deletion of NUCKS (VNKO) did not develop obesity or insulin-resistant phenotypes under an HFD. These studies indicate that hypothalamic NUCKS plays an essential role in regulating glucose homoeostasis and insulin signalling in vivo. © 2015 Authors; published by Portland Press Limited.

  16. Leptin signalling pathways in hypothalamic neurons.

    PubMed

    Kwon, Obin; Kim, Ki Woo; Kim, Min-Seon

    2016-04-01

    Leptin is the most critical hormone in the homeostatic regulation of energy balance among those so far discovered. Leptin primarily acts on the neurons of the mediobasal part of hypothalamus to regulate food intake, thermogenesis, and the blood glucose level. In the hypothalamic neurons, leptin binding to the long form leptin receptors on the plasma membrane initiates multiple signaling cascades. The signaling pathways known to mediate the actions of leptin include JAK-STAT signaling, PI3K-Akt-FoxO1 signaling, SHP2-ERK signaling, AMPK signaling, and mTOR-S6K signaling. Recent evidence suggests that leptin signaling in hypothalamic neurons is also linked to primary cilia function. On the other hand, signaling molecules/pathways mitigating leptin actions in hypothalamic neurons have been extensively investigated in an effort to treat leptin resistance observed in obesity. These include SOCS3, tyrosine phosphatase PTP1B, and inflammatory signaling pathways such as IKK-NFκB and JNK signaling, and ER stress-mitochondrial signaling. In this review, we discuss leptin signaling pathways in the hypothalamus, with a particular focus on the most recently discovered pathways.

  17. Hypothalamic neuropeptides and the regulation of appetite.

    PubMed

    Parker, Jennifer A; Bloom, Stephen R

    2012-07-01

    Neuropeptides released by hypothalamic neurons play a major role in the regulation of feeding, acting both within the hypothalamus, and at other appetite regulating centres throughout the brain. Where classical neurotransmitters signal only within synapses, neuropeptides diffuse over greater distances affecting both nearby and distant neurons expressing the relevant receptors, which are often extrasynaptic. As well as triggering a behavioural output, neuropeptides also act as neuromodulators: altering the response of neurons to both neurotransmitters and circulating signals of nutrient status. The mechanisms of action of hypothalamic neuropeptides with established roles in feeding, including melanin-concentrating hormone (MCH), the orexins, α-melanocyte stimulating hormone (α-MSH), agouti-gene related protein (AgRP), neuropeptide Y, and oxytocin, are reviewed in this article, with emphasis laid on both their effects on appetite regulating centres throughout the brain, and on examining the evidence for their physiological roles. In addition, evidence for the involvement of several putative appetite regulating hypothalamic neuropeptides is assessed including, ghrelin, cocaine and amphetamine-regulated transcript (CART), neuropeptide W and the galanin-like peptides. This article is part of a Special Issue entitled 'Central control of Food Intake'.

  18. Timing of gene expression from different genetic systems in shaping leucine and isoleucine contents of rapeseed (Brassica napus L.) meal.

    PubMed

    Chen, Guolin; Wu, Jianguo; Variath, Murali-Tottekkaad; Shi, Chunhai

    2011-12-01

    Experiments were conducted on rapeseed (Brassica napus L.) using a diallel design with nine parents: Youcai 601, Double 20-4, Huashuang 3, Gaoyou 605, Zhongyou 821, Eyouchangjia, Zhong R-888, Tower and Zheshuang 72. The seed developmental process was divided into five stages, namely initial (days 1-15 after flowering), early (days 16-22 after flowering), middle (days 23-29), late (days 30-36), and maturing (days 37-43) developmental stages. The variation of dynamic genetic effects for leucine and isoleucine contents of rapeseed meal was analysed at five developmental stages, across different environments using the genetic models with time-dependent measures. The results from unconditional and conditional analyses indicated that the expression of diploid embryo, cytoplasmic and diploid maternal plant genes were important for leucine and isoleucine contents at different developmental stages of rapeseed, particularly at the initial and early developmental stages. Among different genetic systems, nutrition quality traits were mainly controlled by the accumulative or net maternal main effects and their GE interaction effects, except at maturity when the net diploid embryo effects were larger. The expression of genes was affected by the environmental conditions on 15, 22, 29 or 36 days after flowering, but was more stable at mature stage. For the isoleucine content the narrow-sense heritabilities on 15, 22, 29, 36, and 43 days after flowering were 43.0, 65.7, 60.1, 65.5 and 78.2%, respectively, while for the leucine content the corresponding narrow-sense heritabilities were relatively smaller. The interaction heritabilities were more important than the general heritabilities at the first three developmental times. The improvement for isoleucine content could be achieved by selection based on the higher narrow-sense heritabilities. Various genetic systems exhibited genetic correlations among the developmental times or leucine and isoleucine contents. A simultaneous

  19. Spectroscopic, thermal and structural studies of new L-leucine and D-leucine complexes with chloranilic acid

    NASA Astrophysics Data System (ADS)

    Pawlukojć, A.; Hetmańczyk, J.; Nowicka-Scheibe, J.; Maurin, Jan K.; Schilf, W.; Rozwadowski, Z.

    2017-04-01

    New molecular complexes of L-leucine and D-leucine with chloranilic acid have been synthesized. Crystal structures of these crystals have been solved; they crystallize in non-centrosymmetric monoclinic P21 space group. In the crystal, leucine molecules exist in protonated form (C6NO2H14+) and chloranilic acid molecules in deprotonated form (C6HCl2O4-). Electronic (UV-Vis) and vibrational absorption (VA) spectra for both materials were collected. Circular dichroism methods such as electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) were used to determine the absolute configuration of new complexes. In both methods a characteristic (-,+) Cotton patterns are observed. In ECD spectra absorption bands are observed at 212 nm for acetonitrile solution and at 202 nm for aqueous solution. VCD spectra (in DMSO-d6 solution) show (-,+) Cotton pattern with strong peaks at 1323 cm-1 (CH rocking mode). Differential scanning calorimetry (DSC) and thermogravimetric (TG) investigations were performed to explore thermal properties of new materials. In DSC curve the decomposition and combustion processes are observed in 220-227 °C. The decomposition process was described by use of TG method and quadruple mass spectrometer (QMS). NMR spectra of pure L-leucine and chloranilic acid as well as L-leucine - chloranilic acid complex in solutions (D2O and DMSO) and in solid state confirm the geometry of molecules in complex both in solution and in solid state.

  20. The Development of Leucine Dehydrogenase and Formate Dehydrogenase Bifunctional Enzyme Cascade Improves the Biosynthsis of L-tert-Leucine.

    PubMed

    Lu, Jixue; Zhang, Yonghui; Sun, Dongfang; Jiang, Wei; Wang, Shizhen; Fang, Baishan

    2016-11-01

    Leucine dehydrogenase (LDH) and formate dehydrogenase (FDH) were assembled together based on a high-affinity interaction between two different cohesins in a miniscaffoldin and corresponding dockerins in LDH and FDH. The miniscaffoldin with two enzymes was further absorbed by regenerated amorphous cellulose (RAC) to form a bifunctional enzyme complex (miniscaffoldin with LDH and FDH adsorbed by RAC, RSLF) in vitro. The enzymatic characteristics of the bifunctional enzyme complex and free enzymes mixture were systematically compared. The synthesis of L-tert-leucine by the RSLF and free enzyme mixture were compared under different concentrations of enzymes, coenzyme, and substrates. The initial L-tert-leucine production rate by RSLF was enhanced by 2-fold compared with that of the free enzyme mixture. Ninety-one grams per liter of L-tert-leucine with an enantiomeric purity of 99 % e.e. was obtained by RSLF multienzyme catalysis. The results indicated that the bifuntional enzyme complex based on cohesin-dockerin interaction has great potential in the synthesis of L-tert-leucine.

  1. The Role of Leucine-Rich Repeat Containing Protein 10 (LRRC10) in Dilated Cardiomyopathy

    PubMed Central

    Brody, Matthew J.; Lee, Youngsook

    2016-01-01

    Leucine-rich repeat containing protein 10 (LRRC10) is a cardiomyocyte-specific member of the Leucine-rich repeat containing (LRRC) protein superfamily with critical roles in cardiac function and disease pathogenesis. Recent studies have identified LRRC10 mutations in human idiopathic dilated cardiomyopathy (DCM) and Lrrc10 homozygous knockout mice develop DCM, strongly linking LRRC10 to the molecular etiology of DCM. LRRC10 localizes to the dyad region in cardiomyocytes where it can interact with actin and α-actinin at the Z-disc and associate with T-tubule components. Indeed, this region is becoming increasingly recognized as a signaling center in cardiomyocytes, not only for calcium cycling, excitation-contraction coupling, and calcium-sensitive hypertrophic signaling, but also as a nodal signaling hub where the myocyte can sense and respond to mechanical stress. Disruption of a wide range of critical structural and signaling molecules in cardiomyocytes confers susceptibility to cardiomyopathies in addition to the more classically studied mutations in sarcomeric proteins. However, the molecular mechanisms underlying DCM remain unclear. Here, we review what is known about the cardiomyocyte functions of LRRC10, lessons learned about LRRC10 and DCM from the Lrrc10 knockout mouse model, and discuss ongoing efforts to elucidate molecular mechanisms whereby mutation or absence of LRRC10 mediates cardiac disease. PMID:27536250

  2. Leucine metabolism in cirrhotic patients with hepatic encephalopathy

    SciTech Connect

    McGhee, A.S.

    1985-01-01

    The purpose of this study was to determine whether increased oxidation of or protein synthesis requiring leucine occurs in cirrhotic patients. Five control subjects and four subjects with cirrhosis were equilibrated on a baseline diet (0.6 g protein per kg ideal body weight (IBW)) with sufficient nonprotein calories to preclude negative nitrogen balance. An additional four patients were equilibrated on the same type of diet with a higher protein level (0.75 g per kg IBW). Control subjects and the patients were then studied during continuous infusion of L-(/sup 15/N, 1-/sup 13/C) leucine in the fasted state and, in the fed state, with a Propac diet which had the same distribution of energy nutrients as the baseline diets. Plasma levels of L-(/sup 15/N, 1-/sup 13/C), L-(1-/sup 13/C) and L-(/sup 15/N) leucine were measured during isotopic steady state by gas chromatography-mass spectrometry and fractional excretion of /sup 13/CO/sup 2/ in breath samples were analyzed by isotopic ratio mass spectrometry. During the fasted and fed states leucine metabolism was measured to quantitate rates of nitrogen flux (Q/sub N/), carbon flux (Q/sub c/) and oxidation to carbon dioxide and water (C). From these measured values, proteins breakdown (B), protein synthesis (S), deamination (X/sup 0/) and reamination (X/sub N/) were calculated. The results showed that protein synthesis and leucine metabolism were identical in controls and patients when both were fed a diet with 0.6 g protein/kg IBW and maintenance level of nonprotein calories. The data also showed that leucine metabolism can be quantitatively and reproducibly measured in subjects with cirrhosis.

  3. Dietary leucine requirement of juvenile Japanese seabass ( Lateolabrax japonicus)

    NASA Astrophysics Data System (ADS)

    Li, Yan; Cheng, Zhenyan; Mai, Kangsen; Ai, Qinghui

    2015-02-01

    A 56-day feeding trial was conducted to examine the dietary leucine requirement of juvenile Japanese seabass in seawater floating net cages (1.5 m × 1.5 m × 2.0 m). Six isonitrogenous (crude protein 40%) and isoenergetic (gross energy 20 kJ g-1) diets were formulated to contain different concentrations of leucine (0.9%, 1.49%, 2.07%, 2.70%, 3.30% and 3.88% of dry matter). Crystalline L-amino acids were supplemented to simulate the whole body amino acid pattern of Japanese seabass except for leucine. Three groups (30 fish individuals each, 8.0 g ± 0.20 g in initial weight) were fed to apparent satiation at 5:00 and 17:30 every day. During the experimental period, the water temperature ranged from 26 to 32δC and salinity from 26 to 30, and the dissolved oxygen was maintained at 7 mg L-1. The results showed that weight gain ( WG), nitrogen retention ( NR), feed efficiency ( FE) and protein efficiency ratio ( PER) were significantly increased when dietary leucine was increased from 0.90% to 2.70% of dry matter, and then declined. WG was the highest when fish were fed D4 containing 2.70% of leucine. No significant differences were observed in body composition among dietary treatments ( P > 0.05). Considering the change of WG, the optimum dietary leucine requirement of juvenile Japanese seabass was either 2.39% of dry matter or 5.68% of dietary protein.

  4. The radiolysis and racemization of leucine on proton irradiation

    NASA Technical Reports Server (NTRS)

    Bonner, W. A.; Lemmon, R. M.; Conzett, H. E.

    1982-01-01

    D- and L-Leucine have been subjected to 39-55 percent radiolysis using 0.11 MeV protons, both with the proton beam passing through the sample or being absorbed by it and with quenching the sample immediately on completion of irradiation or after a 21-day interval. Racemization was small (1.1-1.7 percent) and comparable in all cases, suggesting that radioracemization and secondary degradative effects were not important factors in the recent unsuccessful attempts to induce optical activity in DL-Leucine by partial radiolysis using 0-11 MeV longitudinally polarized protons.

  5. The radiolysis and racemization of leucine on proton irradiation

    NASA Technical Reports Server (NTRS)

    Bonner, W. A.; Lemmon, R. M.; Conzett, H. E.

    1982-01-01

    D- and L-Leucine have been subjected to 39-55 percent radiolysis using 0.11 MeV protons, both with the proton beam passing through the sample or being absorbed by it and with quenching the sample immediately on completion of irradiation or after a 21-day interval. Racemization was small (1.1-1.7 percent) and comparable in all cases, suggesting that radioracemization and secondary degradative effects were not important factors in the recent unsuccessful attempts to induce optical activity in DL-Leucine by partial radiolysis using 0-11 MeV longitudinally polarized protons.

  6. Leptin signaling in astrocytes regulates hypothalamic neuronal circuits and feeding.

    PubMed

    Kim, Jae Geun; Suyama, Shigetomo; Koch, Marco; Jin, Sungho; Argente-Arizon, Pilar; Argente, Jesús; Liu, Zhong-Wu; Zimmer, Marcelo R; Jeong, Jin Kwon; Szigeti-Buck, Klara; Gao, Yuanqing; Garcia-Caceres, Cristina; Yi, Chun-Xia; Salmaso, Natalina; Vaccarino, Flora M; Chowen, Julie; Diano, Sabrina; Dietrich, Marcelo O; Tschöp, Matthias H; Horvath, Tamas L

    2014-07-01

    We found that leptin receptors were expressed in hypothalamic astrocytes and that their conditional deletion led to altered glial morphology and synaptic inputs onto hypothalamic neurons involved in feeding control. Leptin-regulated feeding was diminished, whereas feeding after fasting or ghrelin administration was elevated in mice with astrocyte-specific leptin receptor deficiency. These data reveal an active role of glial cells in hypothalamic synaptic remodeling and control of feeding by leptin.

  7. Regulation of the Immune System by Hypothalamic Releasing Hormones.

    DTIC Science & Technology

    1987-11-01

    AD-All? 395 REGULATION OF THE IMMUNE SYSTEM DY HYPOTHALAMIC 1/1 RELEASING HORMONES (U) TEXAS UNIV MEDICAL BRANCH AT GALVESTON E M SMITH S1 NOV 6? fW...441F004 11 TITLE (Include Security Classification) Regulation of the Immune System by Hypothalamic Releasing Hormones 12 PERSONAL AUTHOR(S) Eric M. Smith...34Hypothalamic releasing hormones , stress, immune system,. L08 ACTH, endorphins, corticosteroids, monokines, neuroimmunomodulation *’" . - " - 19 ABSTRACT

  8. Quantitative role of splanchnic region in leucine metabolism: L-(1-13C,15N)leucine and substrate balance studies

    SciTech Connect

    Yu, Y.M.; Wagner, D.A.; Tredget, E.E.; Walaszewski, J.A.; Burke, J.F.; Young, V.R. )

    1990-07-01

    The role of the splanchnic region (Sp) in whole body leucine metabolism was assessed in six chronically catheterized fasting mongrel dogs and in eight dogs during constant enteral feeding of a complete amino acid solution (0.24 g.kg-1.h-1). We used primed continuous intravenous infusions of L-(1-13C,15N)leucine and L-(1-14C)leucine and measurements of arteriovenous isotope and leucine balance across the gut, liver, and Sp. In the fasted condition, 3.5% of arterial leucine supply was oxidized in the Sp, accounting for 13% of total body leucine oxidation, with 10% by liver. With amino acid feeding (1) leucine carbon and nitrogen fluxes and oxidation were increased (P less than 0.01) at the whole body level; (2) the percent of whole body leucine oxidation occurring in the Sp and liver increased (P less than 0.01) to 41 and 27%, respectively; (3) fractional metabolic utilization of leucine delivered to the Sp was reduced (P less than 0.01) from 47 to 35%; (4) the deamination rate of leucine in the gut was increased (P less than 0.05), along with an increased reamination rate of alpha-ketoisocaproic acid in the Sp (P less than 0.05). These findings reveal that the Sp accounts for a small fraction of whole body leucine oxidation during the fasting condition, but it plays a quantitatively important role in total body leucine oxidation during amino acid feeding; the gut and liver play cooperative roles in controlling leucine supply to peripheral tissues.

  9. The role of astrocytes in the hypothalamic response and adaptation to metabolic signals.

    PubMed

    Chowen, Julie A; Argente-Arizón, Pilar; Freire-Regatillo, Alejandra; Frago, Laura M; Horvath, Tamas L; Argente, Jesús

    2016-09-01

    The hypothalamus is crucial in the regulation of homeostatic functions in mammals, with the disruption of hypothalamic circuits contributing to chronic conditions such as obesity, diabetes mellitus, hypertension, and infertility. Metabolic signals and hormonal inputs drive functional and morphological changes in the hypothalamus in attempt to maintain metabolic homeostasis. However, the dramatic increase in the incidence of obesity and its secondary complications, such as type 2 diabetes, have evidenced the need to better understand how this system functions and how it can go awry. Growing evidence points to a critical role of astrocytes in orchestrating the hypothalamic response to metabolic cues by participating in processes of synaptic transmission, synaptic plasticity and nutrient sensing. These glial cells express receptors for important metabolic signals, such as the anorexigenic hormone leptin, and determine the type and quantity of nutrients reaching their neighboring neurons. Understanding the mechanisms by which astrocytes participate in hypothalamic adaptations to changes in dietary and metabolic signals is fundamental for understanding the neuroendocrine control of metabolism and key in the search for adequate treatments of metabolic diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Inhibition of hypothalamic MCT1 expression increases food intake and alters orexigenic and anorexigenic neuropeptide expression

    PubMed Central

    Elizondo-Vega, Roberto; Cortés-Campos, Christian; Barahona, María José; Carril, Claudio; Ordenes, Patricio; Salgado, Magdiel; Oyarce, Karina; García-Robles, María de los Angeles

    2016-01-01

    Hypothalamic glucosensing, which involves the detection of glucose concentration changes by brain cells and subsequent release of orexigenic or anorexigenic neuropeptides, is a crucial process that regulates feeding behavior. Arcuate nucleus (AN) neurons are classically thought to be responsible for hypothalamic glucosensing through a direct sensing mechanism; however, recent data has shown a metabolic interaction between tanycytes and AN neurons through lactate that may also be contributing to this process. Monocarboxylate transporter 1 (MCT1) is the main isoform expressed by tanycytes, which could facilitate lactate release to hypothalamic AN neurons. We hypothesize that MCT1 inhibition could alter the metabolic coupling between tanycytes and AN neurons, altering feeding behavior. To test this, we inhibited MCT1 expression using adenovirus-mediated transfection of a shRNA into the third ventricle, transducing ependymal wall cells and tanycytes. Neuropeptide expression and feeding behavior were measured in MCT1-inhibited animals after intracerebroventricular glucose administration following a fasting period. Results showed a loss in glucose regulation of orexigenic neuropeptides and an abnormal expression of anorexigenic neuropeptides in response to fasting. This was accompanied by an increase in food intake and in body weight gain. Taken together, these results indicate that MCT1 expression in tanycytes plays a role in feeding behavior regulation. PMID:27677351

  11. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Leucine aminopeptidase test system. 862.1460 Section 862.1460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test...

  12. Enteral leucine and protein synthesis in skeletal and cardiac muscle

    USDA-ARS?s Scientific Manuscript database

    There are three members of the Branch Chain Amino Acids: leucine, isoleucine, and valine. As essential amino acids, these amino acids have important functions which include a primary role in protein structure and metabolism. It is intriguing that the requirement for BCAA in humans comprise about 40–...

  13. Genetic studies of leucine transport in mammalian cells.

    PubMed

    Shotwell, M A; Lobatón, C D; Collarini, E J; Moreno, A; Giles, R E; Oxender, D L

    1984-05-15

    We have taken two approaches to the study of the genetics of leucine transport in mammalian cells. First, from a mutant Chinese hamster ovary cell line that has a temperature-sensitive leucyl-tRNA synthetase, we isolated temperature-resistant revertants with increased leucine transport activity. This transport elevation is reflected by increased Vmax values of leucine uptake and unchanged Km values of uptake. The temperature resistance in each revertant appears to result from the increased transport and not from any change in the leucyl-tRNA synthetase. We conclude that in each revertant there is a stable derepression of amino acid transport system L. In a second approach, we started with a Chinese hamster-human hybrid strain formed by the fusion of a temperature-sensitive leucyl-tRNA synthetase mutant hamster cell line and normal human leukocytes. From this temperature-sensitive hybrid strain we selected temperature-resistant hybrids, one class of which we found to have greatly elevated leucine transport activity. We have allowed human chromosomes to segregate from these high-transport hybrids, promoted by the presence of low concentrations of colcemid. The loss of the high-transport phenotype coincides with the loss of a single small human chromosome, which we are attempting to identify by using G-11 and G-banding staining techniques.

  14. The apo-structure of the leucine sensor Sestrin2 is still elusive

    PubMed Central

    Saxton, Robert A.; Knockenhauer, Kevin E.; Schwartz, Thomas U.; Sabatini, David M.

    2016-01-01

    Sestrin2 is a GATOR2 interacting protein that directly binds leucine and is required for the inhibition of mTORC1 under leucine deprivation, indicating that it is a leucine sensor for the mTORC1 pathway. We recently reported the structure of Sestrin2 in complex with leucine (PDB ID: 5DJ4), and demonstrated that mutations in the leucine-binding pocket alter the affinity of Sestrin2 for leucine and result in a corresponding change in the leucine sensitivity of mTORC1 in cells. A lower resolution structure of human Sestrin2 (PDB ID: 5CUF), which was crystallized in the absence of exogenous leucine, showed Sestrin2 to be in a nearly identical conformation as the leucine-bound structure. Based on this observation, it has been argued that leucine binding does not affect the conformation of Sestrin2 and thus that Sestrin2 may not be a sensor for leucine. Here, we show that simple analysis of the reported “apo”-Sestrin2 structure reveals the clear presence of prominent, unmodeled electron density in the leucine-binding pocket that exactly accommodates the leucine observed in the higher resolution structure. Refining the reported “apo”-structure with leucine eliminates the large FO-FC difference density at this position and improves the working and free R-factors of the model. Consistent with this, our own structure of Sestrin2 crystallized in the absence of exogenous leucine also contains electron density that is best explained by leucine. Thus, the structure of apo-Sestrin2 remains elusive. PMID:27649739

  15. Enhanced production of branched-chain amino acids by Gluconacetobacter europaeus with a specific regional deletion in a leucine responsive regulator.

    PubMed

    Akasaka, Naoki; Ishii, Yuri; Hidese, Ryota; Sakoda, Hisao; Fujiwara, Shinsuke

    2014-12-01

    Vinegar with increased amounts of branched-chain amino acids (BCAAs; valine, leucine and isoleucine) is favorable for human health as BCAAs decrease diet-induced obesity and hyperglycemia. To construct Gluconacetobacter europaeus which produces BCAAs, leucine responsive regulator (GeLrp) is focused and two Gelrp mutants were constructed. Wild-type KGMA0119 didn't produce significant amount of valine (0.13 mM) and leucine (0 mM) and strain KGMA7110 which lacks complete Gelrp accumulated valine (0.48 mM) and leucine (0.11 mM) but showed impaired growth, and it was fully restored in the presence of essential amino acids. Strain KGMA7203 was then constructed with a nonsense mutation at codon Trp132 in the Gelrp, which leads a specific deletion at an estimated ligand-sensing region in the C-terminal domain. KGMA7203 produced greater quantities of valine (0.80 mM) and leucine (0.26 mM) and showed the same growth characteristics as KGMA0119. mRNA levels of BCAAs biosynthesis genes (ilvI and ilvC) and probable BCAAs efflux pump (leuE) were determined by quantitative reverse-transcription PCR. Expression rates of ilvI and ilvC in the two Gelrp disruptants were greater than those in KGMA0119. leuE was highly expressed in KGMA7110 only, suggesting that the accumulation in KGMA7110 culture was caused by increased expression of the biosynthesis genes and abnormal enhanced export of amino acids resulting in impaired cell growth. In contrast, KGMA7203 would achieve the high level production through enhanced expression of the biosynthesis genes without enhancing that for the efflux pump. KGMA7203 was considered advantageous for production of vinegar with higher amounts of valine and leucine.

  16. Restoration of the Hypothalamic-pituitary-adrenal Response to Hypoglycemia in Type 2 Diabetes by Avoiding Chronic Hypoglycemia

    PubMed Central

    Tsuda, Shin-ichi; Konishi, Kazunori; Otoda, Toshiki; Nagai, Takako; Takeda-Watanabe, Ai; Kanasaki, Megumi; Kitada, Munehiro; Nakagawa, Atsushi; Nishizawa, Makoto; Kanasaki, Keizo; Koya, Daisuke

    2016-01-01

    An impaired ability to sense and respond to drug-induced hypoglycemia is a common and serious complication in diabetic patients. The hypothalamic-pituitary-adrenal (HPA) axis activity plays a critical role in the counterregulatory response to hypoglycemia. We herein report a case that experienced restoration of a blunted HPA axis by avoiding hypoglycemia with the use of the DPP-4 inhibitor sitagliptin. PMID:27904111

  17. Hypothalamic control of sleep in aging.

    PubMed

    Rolls, Asya

    2012-09-01

    The timing of sleep and its duration are affected by circadian and homeostatic factors. Physiological and behavioral attributes such as the duration of previous wake period, food availability, temperature, and stress all affect sleep and its quality. As many of these physiological inputs are integrated in the hypothalamus, it is not surprising that this brain structure plays a crucial role in the regulation of sleep. I will discuss this role also in the context of aging, which is associated with changes in both hypothalamic function and the composition of sleep.

  18. Severe hyponatremia caused by hypothalamic adrenal insufficiency.

    PubMed

    Shibata, T; Oeda, T; Saito, Y

    1999-05-01

    A 60-year-old woman was admitted with severe hyponatremia. Basal values of adrenocorticotropic hormone (ACTH), thyroid hormone and cortisol were normal on admission. Impairment of water diuresis was observed by water loading test. Initially, we diagnosed her condition as the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). By provocation test, we finally confirmed that the hyponatremia was caused by hypothalamic adrenal insufficiency. The basal values of ACTH and cortisol might not be sufficient to exclude the possibility of adrenal insufficiency. Therefore, it is necessary to evaluate adrenal function by provocation test or to re-evaluate it after recovery from hyponatremia.

  19. Brain amino acid requirements and toxicity: the example of leucine.

    PubMed

    Yudkoff, Marc; Daikhin, Yevgeny; Nissim, Ilana; Horyn, Oksana; Luhovyy, Bohdan; Luhovyy, Bogdan; Lazarow, Adam; Nissim, Itzhak

    2005-06-01

    Glutamic acid is an important excitatory neurotransmitter of the brain. Two key goals of brain amino acid handling are to maintain a very low intrasynaptic concentration of glutamic acid and also to provide the system with precursors from which to synthesize glutamate. The intrasynaptic glutamate level must be kept low to maximize the signal-to-noise ratio upon the release of glutamate from nerve terminals and to minimize the risk of excitotoxicity consequent to excessive glutamatergic stimulation of susceptible neurons. The brain must also provide neurons with a constant supply of glutamate, which both neurons and glia robustly oxidize. The branched-chain amino acids (BCAAs), particularly leucine, play an important role in this regard. Leucine enters the brain from the blood more rapidly than any other amino acid. Astrocytes, which are in close approximation to brain capillaries, probably are the initial site of metabolism of leucine. A mitochondrial branched-chain aminotransferase is very active in these cells. Indeed, from 30 to 50% of all alpha-amino groups of brain glutamate and glutamine are derived from leucine alone. Astrocytes release the cognate ketoacid [alpha-ketoisocaproate (KIC)] to neurons, which have a cytosolic branched-chain aminotransferase that reaminates the KIC to leucine, in the process consuming glutamate and providing a mechanism for the "buffering" of glutamate if concentrations become excessive. In maple syrup urine disease, or a congenital deficiency of branched-chain ketoacid dehydrogenase, the brain concentration of KIC and other branched-chain ketoacids can increase 10- to 20-fold. This leads to a depletion of glutamate and a consequent reduction in the concentration of brain glutamine, aspartate, alanine, and other amino acids. The result is a compromise of energy metabolism because of a failure of the malate-aspartate shuttle and a diminished rate of protein synthesis.

  20. Characterization of leucine zipper complexes by electrospray ionization mass spectrometry.

    PubMed Central

    Wendt, H.; Dürr, E.; Thomas, R. M.; Przybylski, M.; Bosshard, H. R.

    1995-01-01

    The development of "soft" ionization methods has enabled the mass spectrometric analysis of higher-order structural features of proteins. We have applied electrospray ionization mass spectrometry (ESI-MS) to the analysis of the number and composition of polypeptide chains in homomeric and heteromeric leucine zippers. In comparison with other methods that have been used to analyze leucine zippers, such as analytical ultracentrifugation, gel chromatography, or electrophoretic band shift assays, ESI-MS is very fast and highly sensitive and provides a straightforward way to distinguish between homomeric and heteromeric coiled-coil structures. ESI-MS analyses were carried out on the parallel dimeric leucine zipper domain GCN4-p1 of the yeast transcription factor GCN4 and on three synthetic peptides with the sequences Ac-EYEALEKKLAAX1EAKX2QALEKKLEALEHG-amide: peptide LZ (X1, X2 = Leu), peptide LZ(12A) (X1 = Ala, X2 = Leu), and peptide LZ(16N) (X1 = Leu, X2 = Asn). Equilibrium ultracentrifugation analysis showed that LZ forms a trimeric coiled coil and this could be confirmed unequivocally by ESI-MS as could the dimeric nature of GCN4-p1. The formation of heteromeric two- and three-stranded leucine zippers composed of chains from LZ and LZ(12A), or from GCN4-p1 and LZ, was demonstrated by ESI-MS and confirmed by fluorescence quenching experiments on fluorescein-labeled peptides. The results illustrate the adaptability and flexibility of the leucine zipper motif, properties that could be useful to the design of specific protein assemblies by way of coiled-coil domains. PMID:8520482

  1. Relation between plasma and tissue parameters of leucine metabolism in fed and starved rats

    SciTech Connect

    Vazquez, J.A.; Paul, H.S.; Adibi, S.A.

    1986-06-01

    By use of a primed continuous infusion of (1-/sup 14/C)leucine, the authors investigated parameters of leucine metabolism in plasma, expired air, and tissues of fed and 48-h starved rats. The ratios of muscle to plasma specific activity of ..cap alpha..-ketoisocaproate (KIC) in fed and starved rats were not significantly different from 1. The ratio of muscle to plasma specific activity of leucine was also not significantly different from 1 in fed rats, but was significantly lower than 1 in starved rats. The rate of leucine oxidation was 28-34% higher when calculation was based on plasma KIC rather than leucine specific activity. However, starvation significantly increased the rate of leucine oxidation with either specific activity. The rates of leucine incorporation into whole-body protein, calculated as the difference between plasma leucine turnover and oxidation, were unaffected by starvation, but the incorporations into total protein measured directly were significantly decreased in liver and muscle. They conclude that a) leucine or KIC specific activity in muscle is better predicted by plasma KIC than leucine specific activity, and b) the difference between rates of plasma leucine turnover and oxidation does not appear to be a valid measurement of leucine incorporation into whole-body protein.

  2. Giant solid-cystic hypothalamic hamartoma. Case report.

    PubMed

    Dorfer, Christian; Kasprian, Gregor; Mühlebner, Angelika; Czech, Thomas

    2011-02-01

    Hypothalamic hamartomas are rare lesions for which different classification schemes have been proposed. The authors report on an exceptionally large solid-cystic hamartoma that led to hydrocephalus, precocious puberty, and intractable gelastic seizures. They discuss potential mechanisms of the development of hypothalamic hamartomas.

  3. Lef1-dependent hypothalamic neurogenesis inhibits anxiety

    PubMed Central

    Xie, Yuanyuan; Panahi, Samin; Gaynes, John A.; Watters, Harrison N.; Zhou, Dingxi; Xue, Hai-Hui; Fung, Camille M.; Levine, Edward M.; Letsou, Anthea; Brennan, K. C.

    2017-01-01

    While innate behaviors are conserved throughout the animal kingdom, it is unknown whether common signaling pathways regulate the development of neuronal populations mediating these behaviors in diverse organisms. Here, we demonstrate that the Wnt/ß-catenin effector Lef1 is required for the differentiation of anxiolytic hypothalamic neurons in zebrafish and mice, although the identity of Lef1-dependent genes and neurons differ between these 2 species. We further show that zebrafish and Drosophila have common Lef1-dependent gene expression in their respective neuroendocrine organs, consistent with a conserved pathway that has diverged in the mouse. Finally, orthologs of Lef1-dependent genes from both zebrafish and mouse show highly correlated hypothalamic expression in marmosets and humans, suggesting co-regulation of 2 parallel anxiolytic pathways in primates. These findings demonstrate that during evolution, a transcription factor can act through multiple mechanisms to generate a common behavioral output, and that Lef1 regulates circuit development that is fundamentally important for mediating anxiety in a wide variety of animal species. PMID:28837622

  4. Estrogen Signaling in Hypothalamic Circuits Controling Reproduction

    PubMed Central

    Kelly, Martin J.; Qiu, Jian

    2010-01-01

    It is well known that many of the actions of 17β-estradiol (E2) in the central nervous system are mediated via intracellular receptor/transcription factors that interact with steroid response elements on target genes. However, there is compelling evidence for membrane steroid receptors for estrogen in hypothalamic and other brain neurons. Yet, it is not well understood how estrogen signals via membrane receptors, and how these signals impact not only membrane excitability but also gene transcription in neurons that modulate GnRH neuronal excitability. Indeed, it has been known for sometime that E2 can rapidly alter neuronal activity within seconds, indicating that some cellular effects can occur via membrane delimited events. In addition, E2 can affect second messenger systems including calcium mobilization and a plethora of kinases to alter cell signaling. Therefore, this review will consider our current knowledge of rapid membrane-initiated and intracellular signaling by E2 in hypothalamic neurons critical for reproductive function. PMID:20807512

  5. Leucine kinetics from (2H3)- and ( sup 13 C)leucine infused simultaneously by gut and vein

    SciTech Connect

    Hoerr, R.A.; Matthews, D.E.; Bier, D.M.; Young, V.R. )

    1991-01-01

    In amino acid tracer kinetic studies of the fed state, ingested amino acid may be taken up during its initial transit through splanchnic tissues and thus not enter the plasma compartment where tracer is infused. To investigate this possibility, adult human subjects received simultaneous intravenous (iv) and intragastric (ig) leucine tracer infusions, first during a postabsorptive (PA) 4-h primed continuous ig infusion of L-(1-13C)-leucine and L-(5,5,5-2H3)leucine iv, followed on a separate day by a fed infusion, in which an ig infusion of a liquid formula was started 2 h before the tracer infusion and continued throughout the tracer study. Subjects were accustomed to a constant experimental diet supplying 1.5 g protein.kg-1.day-1 and 41-45 kcal.kg-1.day-1 for 7 and 12 days before the PA and fed studies, respectively. For the PA study, plasma enrichment for the ig tracer was 3.34 +/- 0.27 (SE) mol + excess and for the iv tracer it was 4.18 +/- 0.10 (P less than 0.02). Enrichments of alpha-keto-isocaproic acid (KIC) were 3.24 +/- 0.16 (ig) and 3.02 +/- 0.14 (iv), respectively (not significant (NS)). For the fed study, plasma leucine enrichment for the ig tracer was 2.15 +/- 0.14 and for the iv tracer was 2.84 +/- 0.09 (P less than 0.02). KIC enrichments were 2.02 +/- 0.08 (ig) and 2.24 +/- 0.08 (iv), respectively (NS). In the PA study, the ratio of the plasma leucine enrichments for the ig and iv tracers was 0.80 +/- 0.06 and in the fed experiment, 0.76 +/- 0.05, respectively.

  6. Relationship between surface concentration of L-leucine and bulk powder properties in spray dried formulations.

    PubMed

    Mangal, Sharad; Meiser, Felix; Tan, Geoffrey; Gengenbach, Thomas; Denman, John; Rowles, Matthew R; Larson, Ian; Morton, David A V

    2015-08-01

    The amino acid L-leucine has been demonstrated to act as a lubricant and improve the dispersibility of otherwise cohesive fine particles. It was hypothesized that optimum surface L-leucine concentration is necessary to achieve optimal surface and bulk powder properties. Polyvinylpyrrolidone was spray dried with different concentration of L-leucine and the change in surface composition of the formulations was determined using X-ray photoelectron spectroscopy (XPS) and time of flight-secondary ion mass spectrometry (ToF-SIMS). The formulations were also subjected to powder X-ray diffraction analysis in order to understand the relationship between surface concentration and solid-state properties of L-leucine. In addition, the morphology, surface energy and bulk cohesion of spray dried formulations were also assessed to understand the relation between surface L-leucine concentration and surface and bulk properties. The surface concentration of L-leucine increased with higher feed concentrations and plateaued at about 10% L-leucine. Higher surface L-leucine concentration also resulted in the formation of larger L-leucine crystals and not much change in crystal size was noted above 10% L-leucine. A change in surface morphology of particles from spherical to increasingly corrugated was also observed with increasing surface l-leucine concentration. Specific collapsed/folded over particles were only seen in formulations with 10% or higher l-leucine feed concentration suggesting a change in particle surface formation process. In addition, bulk cohesion also reduced and approached a minimum with 10% L-leucine concentration. Thus, the surface concentration of L-leucine governs particle formation and optimum surface L-leucine concentration results in optimum surface and bulk powder properties.

  7. Activation of the hypothalamic feeding centre upon visual prey detection

    PubMed Central

    Muto, Akira; Lal, Pradeep; Ailani, Deepak; Abe, Gembu; Itoh, Mari; Kawakami, Koichi

    2017-01-01

    The visual system plays a major role in food/prey recognition in diurnal animals, and food intake is regulated by the hypothalamus. However, whether and how visual information about prey is conveyed to the hypothalamic feeding centre is largely unknown. Here we perform real-time imaging of neuronal activity in freely behaving or constrained zebrafish larvae and demonstrate that prey or prey-like visual stimuli activate the hypothalamic feeding centre. Furthermore, we identify prey detector neurons in the pretectal area that project to the hypothalamic feeding centre. Ablation of the pretectum completely abolishes prey capture behaviour and neurotoxin expression in the hypothalamic area also reduces feeding. Taken together, these results suggest that the pretecto-hypothalamic pathway plays a crucial role in conveying visual information to the feeding centre. Thus, this pathway possibly converts visual food detection into feeding motivation in zebrafish. PMID:28425439

  8. RNA-seq analysis of the hypothalamic transcriptome reveals the networks regulating physiopathological progress in the diabetic GK rat

    PubMed Central

    Meng, Yuhuan; Guan, Yujia; Zhang, Wenlu; Wu, Yu-e; Jia, Huanhuan; Zhang, Yu; Zhang, Xiuqing; Du, Hongli; Wang, Xiaoning

    2016-01-01

    The Goto-Kakizaki (GK) rat is an animal model of non-obese type 2 diabetes (T2D). The GK rat was generated through the introduction of various genetic mutations from continuous inbreeding; these rats develop diabetes spontaneously. The mutated genes in GK rats may play key roles in the regulation of diabetes. The hypothalamus plays a central role in systematic energy homeostasis. Here, the hypothalamic transcriptomes in GK and Wistar rats at 4, 8 and 12 weeks were investigated by RNA-seq, and multiple variants and gene expression profiles were obtained. The number of variants identified from GK rats was significantly greater than that of Wistar rats, indicating that many variants were fixed and heritable in GK rats after selective inbreeding. The differential gene expression analysis indicated that GK rats had a dysfunctional hypothalamic melanocortin system and attenuation of the hypothalamic glucose-sensing pathway. In addition, we generated integrated gene network modules by combining the protein-protein interaction (PPI) network, co-expression network and mutations in GK and Wistar rats. In the modules, GK-specific genes, such as Bad, Map2k2, Adcy3, Adcy2 and Gstm6, may play key roles in hypothalamic regulation in GK rats. Our research provides a comprehensive map of the abnormalities in the GK rat hypothalamus, which reveals the new mechanisms of pathogenesis of T2D. PMID:27677945

  9. The contribution of muscle, kidney and splanchnic tissues to leucine transamination in humans.

    PubMed

    Garibotto, Giacomo; Verzola, Daniela; Vettore, Monica; Tessari, Paolo

    2017-09-11

    The first steps of leucine utilization are reversible deamination to α-ketoisocaproic acid (α-KIC) and irreversible oxidation. Recently the regulatory role of leucine deamination over oxidation was underlined in rodents. Our aim was to measure leucine deamination and reamination in the whole-body, in respect to previously determined rates across organs, in humans. By leucine and KIC isotope kinetics, we determined whole-body leucine deamination and reamination, and we compared these rates to those already reported across the sampled organs. As an in vivo counterpart of the "metabolon" concept, we analysed ratios between oxidation to either deamination or reamination. Leucine deamination to KIC was greater than KIC reamination to leucine in the whole-body (p=0.005), muscle (p=0.005) and the splanchnic area (p=0.025).These rates were not significantly different in the kidneys. Muscle accounted for ≈60% and ≈78%, the splanchnic bed for ≈15% and ≈15%, and the kidney for ≈12% and ≈18%, of whole-body leucine deamination and reamination rates, respectively. In the kidney, percent leucine oxidation over either deamination or reamination was >3-fold greater than muscle and the splanchnic bed. Skeletal muscle contributes by the largest fraction of leucine deamination, reamination and oxidation. However, in relative terms, the kidney plays a key role in leucine oxidation.

  10. Supplemental dietary leucine and the skeletal muscle anabolic response to essential amino acids.

    PubMed

    Pasiakos, Stefan M; McClung, James P

    2011-09-01

    Skeletal muscle protein synthesis (MPS) is regulated by a number of dietary factors, to include essential amino acids (EAAs). Leucine, a branched-chain amino acid, has been identified as a stimulator of MPS in many cell culture and animal studies. However, whether supplemental leucine exerts a unique stimulatory effect, as compared to other EAAs, on muscle anabolism in humans has not been clearly demonstrated. A recent study found no improvement in resting MPS in adults who consumed a 10 g EAA supplement providing added leucine (3.5 g leucine) when compared to a control 10 g EAA supplement (1.8 g leucine). These findings suggest that added leucine is unnecessary for the stimulation of MPS when sufficient EAAs are provided; however, the study of supplemental leucine during conditions such as endurance exercise, caloric deprivation, and ageing may be warranted.

  11. Regulation of the plasma amino acid profile by leucine via the system L amino acid transporter.

    PubMed

    Zhen, Hongmin; Nakamura, Koichi; Kitaura, Yasuyuki; Kadota, Yoshihiro; Ishikawa, Takuya; Kondo, Yusuke; Xu, Minjun; Shimomura, Yoshiharu

    2015-01-01

    Plasma concentrations of amino acids reflect the intracellular amino acid pool in mammals. However, the regulatory mechanism requires clarification. In this study, we examined the effect of leucine administration on plasma amino acid profiles in mice with and without the treatment of 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH) or rapamycin as an inhibitor of system L or mammalian target of rapamycin complex 1, respectively. The elevation of plasma leucine concentration after leucine administration was associated with a significant decrease in the plasma concentrations of isoleucine, valine, methionine, phenylalanine, and tyrosine; BCH treatment almost completely blocked the leucine-induced decrease in plasma amino acid concentrations. Rapamycin treatment had much less effects on the actions of leucine than BCH treatment. These results suggest that leucine regulates the plasma concentrations of branched-chain amino acids, methionine, phenylalanine, and tyrosine, and that system L amino acid transporters are involved in the leucine action.

  12. Photolysis of rac-leucine with circularly polarized synchrotron radiation.

    PubMed

    Meierhenrich, Uwe J; Filippi, Jean-Jacques; Meinert, Cornelia; Hoffmann, Søren V; Bredehöft, Jan Hendrik; Nahon, Laurent

    2010-06-01

    Amino acids that pass the RNA machinery in living organisms occur in L-configuration. The question on the evolutionary origin of this biomolecular asymmetry remains unanswered to this day. Amino acids were detected in artificially produced interstellar ices, and L-enantiomer-enriched amino acids were identified in CM-type meteorites. This hints at a possible interstellar/circumstellar origin of the amino acids themselves as well as their stereochemical asymmetry. Based upon the current knowledge about the occurrence of circularly-polarized electromagnetic radiation in interstellar environments, we subjected rac-leucine to far-UV circularly-polarized synchrotron radiation. Asymmetric photolysis was followed by an analysis in an enantioselective GC/MS system. Here, we report on an advanced photolysis rate of more than 99% for leucine. The results indicate that high photolysis rates can occur under the chosen conditions, favoring enantioselective photolysis. In 2014, the obtained results will be reexamined by cometary mission Rosetta.

  13. Determination of Levo-Rotatory Leucine by a Fluorescent Probe

    NASA Astrophysics Data System (ADS)

    Cheng, D.; Zhu, H.

    2015-03-01

    With a certain concentration of Michaelis buffer solution (pH 6.1), and in the presence of CTMAB, the fluorescence intensity of fluorescein, which is quenched by Pd 2+ , can be enhanced after adding a certain content of L-leucine. Thereby, we establish a fluorescence spectrometry method to detect the content of L-leucine, the added amount of which is proportional to the fluorescence enhancement. When the excitation slit width is 3 nm and the emission slit width is 5 nm, we obtain the following results: correlation coefficient R = 0.9981, linear range 0.125-1.375 mg/l, and detection limit 0.00028 mg/l.

  14. Inverse relationship of leucine flux and oxidation to free fatty acid availability in vivo.

    PubMed Central

    Tessari, P; Nissen, S L; Miles, J M; Haymond, M W

    1986-01-01

    To determine the effect of fatty acid availability on leucine metabolism, 14-h fasted dogs were infused with either glycerol or triglyceride plus heparin, and 46-h fasted dogs were infused with either nicotinic acid or nicotinic acid plus triglyceride and heparin. Leucine metabolism was assessed using a simultaneous infusion of L-[4,5-3H]leucine and alpha-[1-14C]ketoisocaproate. Leucine, alpha-ketoisocaproate (KIC), and totalleucine carbon (leucine plus KIC) flux and oxidation rates were calculated at steady state. In 14-h fasted animals, infusion of triglyceride and heparin increased plasma free fatty acids (FFA) by 0.7 mM (P less than 0.01) and decreased leucine (P less than 0.01), total leucine carbon flux (P less than 0.02), and oxidation (P less than 0.05). The estimated rate of leucine utilization not accounted for by oxidation and KIC flux decreased, but the changes were not significant. During glycerol infusion, leucine and KIC flux and oxidation did not change. In 46-h fasted dogs, nicotinic acid decreased FFA by 1.0 mM (P less than 0.01) and increased (P less than 0.05) the rate of leucine and total leucine carbon flux, but did not affect KIC flux. Leucine oxidation increased (P less than 0.01) by nearly threefold, whereas nonoxidized leucine utilization decreased. Infusion of triglyceride plus heparin together with nicotinic acid blunted some of the responses observed with nicotinic acid alone. In that changes in oxidation under steady state condition reflect changes in net leucine balance, these data suggest that FFA availability may positively affect the sparing of at least one essential amino acid and may influence whole body protein metabolism. PMID:3080479

  15. Dietary L-leucine supplementation enhances intestinal development in suckling piglets.

    PubMed

    Sun, Yuli; Wu, Zhenlong; Li, Wei; Zhang, Chen; Sun, Kaiji; Ji, Yun; Wang, Bin; Jiao, Ning; He, Beibei; Wang, Weiwei; Dai, Zhaolai; Wu, Guoyao

    2015-08-01

    L-Leucine is a signaling amino acid in animal metabolism. It is unknown whether supplementing L-leucine to breast-fed neonates may enhance their small-intestinal development. This hypothesis was tested with a piglet model. Seven-day-old sow-reared pigs with an average birth weight of 1.45 kg were assigned randomly to the control or leucine group (n = 30/group). Piglets in the leucine group were orally administrated with 1.4 g L-leucine/kg body weight, whereas piglets in the control group received isonitrogenous L-alanine, twice daily for 14 days. The supplemental L-leucine amounted to 200 % of L-leucine intake from sow's milk by 7-day-old pigs. At the end of the 2-week experiment, tissue samples were collected for determining intestinal morphology, expression of genes for intestinal leucine transporters (real-time RT-PCR and western blot analysis), and plasma metabolites and hormones. L-leucine administration increased (P < 0.05) villus height in the duodenum, an elevated ratio of villus height to crypt depth in the duodenum and ileum, plasma concentrations of leucine, glutamine and asparagine, as well as body-weight gains. mRNA levels for L-leucine transporters (SLC6A14, SLC6A19 and SLC7A9) and the abundance of the ATB(0,+) protein were increased (P < 0.05) but those for SLC7A7 mRNA and the LAT2 protein were decreased (P < 0.05) in the jejunum of leucine-supplemented piglets, compared with the control. Plasma concentrations of ammonia, urea, triglycerides, and growth-related hormones did not differ between the control and leucine groups. Collectively, these results indicate that L-leucine supplementation improves intestinal development and whole-body growth in suckling piglets with a normal birth weight.

  16. Jerking & confused: Leucine-rich glioma inactivated 1 receptor encephalitis.

    PubMed

    Casault, Colin; Alikhani, Katayoun; Pillay, Neelan; Koch, Marcus

    2015-12-15

    This is a case of autoimmune encephalitis with features of faciobrachial dystonic seizures (FBDS) pathognomonic for Leucine Rich Glioma inactivated (LGI)1 antibody encephalitis. This voltage-gated potassium channel complex encephalitis is marked by rapid onset dementia, FBDS and hyponatremia, which is sensitive to management with immunotherapy including steroids, IVIG and other agents. In this case report we review the clinical features, imaging and management of this condition. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

  17. Enzyme-linked immunosorbent assay for leucine and methionine enkephalins

    SciTech Connect

    Zamboni, G.; Jones, C.A.; Hughes, J.

    1983-04-01

    An enzyme-linked immunosorbent assay for enkephalins was developed by coupling the peptides to a carrier molecule (bovine serum albumin) in order to allow the antibody-antigen reaction to take place in the solid phase. The assay was shown to be highly reproducible. Its sensitivity was 14 nmol/liter for leucine enkephalin and 27 nmol/liter for methionine enkephalin, which is similar to that obtained when the same antibodies were used in radioimmunoassay.

  18. Artificial leucine rich repeats as new scaffolds for protein design.

    PubMed

    Baabur-Cohen, Hemda; Dayalan, Subashini; Shumacher, Inbal; Cohen-Luria, Rivka; Ashkenasy, Gonen

    2011-04-15

    The leucine rich repeat (LRR) motif that participates in many biomolecular recognition events in cells was suggested as a general scaffold for producing artificial receptors. We describe here the design and first total chemical synthesis of small LRR proteins, and their structural analysis. When evaluating the tertiary structure as a function of different number of repeating units (1-3), we were able to find that the 3-repeats sequence, containing 90 amino acids, folds into the expected structure.

  19. Increased hypothalamic serotonin turnover in inflammation-induced anorexia.

    PubMed

    Dwarkasing, J T; Witkamp, R F; Boekschoten, M V; Ter Laak, M C; Heins, M S; van Norren, K

    2016-05-20

    Anorexia can occur as a serious complication of disease. Increasing evidence suggests that inflammation plays a major role, along with a hypothalamic dysregulation characterized by locally elevated serotonin levels. The present study was undertaken to further explore the connections between peripheral inflammation, anorexia and hypothalamic serotonin metabolism and signaling pathways. First, we investigated the response of two hypothalamic neuronal cell lines to TNFα, IL-6 and LPS. Next, we studied transcriptomic changes and serotonergic activity in the hypothalamus of mice after intraperitoneal injection with TNFα, IL-6 or a combination of TNFα and IL-6. In vitro, we showed that hypothalamic neurons responded to inflammatory mediators by releasing cytokines. This inflammatory response was associated with an increased serotonin release. Mice injected with TNFα and IL-6 showed decreased food intake, associated with altered expression of inflammation-related genes in the hypothalamus. In addition, hypothalamic serotonin turnover showed to be elevated in treated mice. Overall, our results underline that peripheral inflammation reaches the hypothalamus where it affects hypothalamic serotoninergic metabolism. These hypothalamic changes in serotonin pathways are associated with decreased food intake, providing evidence for a role of serotonin in inflammation-induced anorexia.

  20. Identification and characterization of Paragonimus westermani leucine aminopeptidase.

    PubMed

    Song, Su-Min; Park, Joon-Hyung; Kim, Jin; Kim, Suk-Il; Hong, Yeon-Chul; Kong, Hyun-Hee; Chung, Dong-Il

    2008-09-01

    Paragonimus westermani is a tissue-invading trematode parasite that causes inflammatory lung disease as well as systemic infections including cerebral invasion in carnivorous mammals. While aminopeptidases play important roles in trematodes in the catabolism of host hemoglobin, an essential source of nutrient for the parasite, little is known about aminopeptidase in Paragonimus. Presently, we isolated a cDNA encoding a 58 kDa P. westermani leucine aminopeptidase (PwLAP). Deduced amino acid sequence of PwLAP exhibited significant sequence homology with LAP from Schistosoma spp. and Fasciola hepatica. Biochemical analysis of the recombinant PwLAP protein demonstrated preferential substrate specificity for Leu-NHMec and inhibition by EDTA, 1,10-phenanthroline, and bestatin, which are conserved characteristics of the M17 family of leucine aminopeptidase. PwLAP exhibited relatively higher enzyme activity in the presence of Mn2+ compared to Schistosoma mansoni LAP. Based on the biochemical properties and immunohistochemical analysis, PwLAP is concluded to represent a leucine aminopeptidase. The enzyme is most likely responsible for the catabolism of host hemoglobin, and, hence, represents a potential target of Paragonimus chemotherapy.

  1. Characterization of a leucine aminopeptidase of Babesia gibsoni.

    PubMed

    Jia, H; Terkawi, M A; Aboge, G O; Goo, Y-K; Luo, Y; Li, Y; Yamagishi, J; Nishikawa, Y; Igarashi, I; Sugimoto, C; Fujisaki, K; Xuan, X

    2009-08-01

    Peptidases of parasitic protozoa are currently under intense investigation in order to identify novel virulence factors, drug targets, and vaccine candidates, except in Babesia. Leucine aminopeptidases in protozoa, such as Plasmodium and Leishmania, have been identified to be involved in free amino acid regulation. We report here the molecular and enzymatic characterization, as well as the localization of a leucine aminopeptidase, a member of the M17 cytosolic aminopeptidase family, from B. gibsoni (BgLAP). A functional recombinant BgLAP (rBgLAP) expressed in Escherichia coli efficiently hydrolysed synthetic substrates for aminopeptidase, a leucine substrate. Enzyme activity of the rBgLAP was found to be optimum at pH 8.0 and at 37 degrees C. The substrate profile was slightly different from its homologue in P. falciprum. The activity was also strongly dependent on metal divalent cations, and was inhibited by bestatin, which is a specific inhibitor for metalloprotease. These results indicated that BgLAP played an important role in free amino acid regulation.

  2. Leucine incorporation into mixed skeletal muscle protein in humans

    SciTech Connect

    Nair, K.S.; Halliday, D.; Griggs, R.C. Clinical Research Centre, Harrow )

    1988-02-01

    Fractional mixed skeletal muscle protein synthesis (FMPS) was estimated in 10 postabsorptive healthy men by determining the increment in the abundance of ({sup 13}C)-leucine in quadriceps muscle protein during an intravenous infusion of L-(1-{sup 13}C)leucine. Whole-body muscle protein synthesis (MPS) was calculated based on the estimation of muscle mass from creatinine excretion and compared with whole-body protein synthesis (WBPS) calculated from the nonoxidative portion of leucine flux. A significant correlation was found between MPS. The contribution of MPS to WBPS was 27 {plus minus} 1%, which is comparable to the reports in other species. Morphometric analyses of adjacent muscle samples in eight subjects demonstrated that the biopsy specimens consisted of 86.5 {plus minus} 2% muscular as opposed to other tissues. Because fiber type composition varies between biopsies, the authors examined the relationship between proportions of each fiber type and FMPS. Variation in the composition of biopsies and in fiber-type proportion did not affect the estimation of muscle protein synthesis rate. They conclude that stable isotope techniques using serial needle biopsies permit the direct measurement of FMPS in humans and that this estimation is correlated with an indirect estimation of WBPS.

  3. Controlling Mechanical Properties of Bis-leucine Oxalyl Amide Gels

    NASA Astrophysics Data System (ADS)

    Chang, William; Carvajal, Daniel; Shull, Kenneth

    2011-03-01

    is-leucine oxalyl amide is a low molecular weight gelator capable of gelling polar and organic solvents. A fundamental understanding of self-assembled systems can lead to new methods in drug delivery and the design of new soft material systems. An important feature of self-assembled systems are the intermolecular forces between solvent and gelator molecule; by changing the environment the gel is in, the mechanical properties also change. In this project two variables were considered: the degree of neutralization present for the gelator molecule from neutral to completely ionized, and the concentration of the gelator molecule, from 1 weight percent to 8 weight percent in 1-butanol. Mechanical properties were studied using displacement controlled indentation techniques and temperature sweep rheometry. It has been found that properties such as the storage modulus, gelation temperature and maximum stress allowed increase with bis-leucine oxalyl amide concentration. The results from this study establish a 3-d contour map between the gelator concentration, the gelator degree of ionization and mechanical properties such as storage modulus and maximum stress allowed. The intermolecular forces between the bis-leucine low molecular weight gelator and 1-butanol govern the mechanical properties of the gel system, and understanding these interactions will be key to rationally designed self-assembled systems.

  4. MEMBRANE ESTROGEN RECEPTOR REGULATION OF HYPOTHALAMIC FUNCTION

    PubMed Central

    Micevych, Paul E.; Kelly, Martin J.

    2012-01-01

    Over the decades, our understanding of estrogen receptor (ER) function has evolved. Today we are confronted by at least two nuclear ERs: ERα and ERβ; and a number of putative membrane ERs, including ERα, ERβ, ER-X, GPR30 and Gq-mER. These receptors all bind estrogens or at least estrogenic compounds and activate intracellular signaling pathways. In some cases, a well-defined pharmacology, and physiology has been discovered. In other cases, the identity or the function remains to be elucidated. This mini-review attempts to synthesize our understanding of 17β-estradiol membrane signaling within hypothalamic circuits involved in homeostatic functions focusing on reproduction and energy balance. PMID:22538318

  5. Lateral Hypothalamic Circuits for Feeding and Reward

    PubMed Central

    Stuber, Garret D.; Wise, Roy A.

    2016-01-01

    In experiments conducted over 60 years ago, the lateral hypothalamic area (LHA) was identified as a critical neuroanatomical substrate for motivated behavior. Electrical stimulation of the LHA induces voracious feeding even in non-restricted animals. In the absence of food, animals will work tirelessly, often lever-pressing 1000’s of times per hour, for electrical stimulation at the same site that provokes feeding, drinking, and other species-typical motivated behaviors. Here we review the classic findings from electrical stimulation studies and integrate them with more recent work that has utilized contemporary circuit-based approaches to study the LHA. We identify specific anatomically and molecularly defined LHA elements that integrate diverse information arising from cortical, extended amygdala, and basal forebrain networks to ultimately generate a highly specified and invigorated behavioral state conveyed via LHA projections to downstream reward and feeding specific circuits. PMID:26814589

  6. Lateral hypothalamic circuits for feeding and reward.

    PubMed

    Stuber, Garret D; Wise, Roy A

    2016-02-01

    In experiments conducted over 60 years ago, the lateral hypothalamic area (LHA) was identified as a critical neuroanatomical substrate for motivated behavior. Electrical stimulation of the LHA induces voracious feeding even in well-fed animals. In the absence of food, animals will work tirelessly, often lever-pressing thousands of times per hour, for electrical stimulation at the same site that provokes feeding, drinking and other species-typical motivated behaviors. Here we review the classic findings from electrical stimulation studies and integrate them with more recent work that has used contemporary circuit-based approaches to study the LHA. We identify specific anatomically and molecularly defined LHA elements that integrate diverse information arising from cortical, extended amygdala and basal forebrain networks to ultimately generate a highly specified and invigorated behavioral state conveyed via LHA projections to downstream reward and feeding-specific circuits.

  7. ALTERED HYPOTHALAMIC FUNCTION IN DIET-INDUCED OBESITY

    PubMed Central

    Velloso, L A; Schwartz, M W

    2012-01-01

    Energy homeostasis involves a complex network of hypothalamic and extra-hypothalamic neurons that transduce hormonal, nutrient and neuronal signals into responses that ultimately match caloric intake to energy expenditure and thereby promote stability of body fat stores. Growing evidence suggests that rather than reflecting a failure to regulate caloric intake, common forms of obesity involve fundamental changes to this homeostatic system that favor the defense of an elevated level of body adiposity. This article reviews emerging evidence that during high-fat feeding, obesity pathogenesis involves fundamental alteration of hypothalamic systems that regulate food intake and energy expenditure. PMID:21386802

  8. The pathway of leucine to mevalonate in halophilic archaea: efficient incorporation of leucine into isoprenoidal lipid with the involvement of isovaleryl-CoA dehydrogenase in Halobacterium salinarum.

    PubMed

    Yamauchi, Noriaki

    2010-01-01

    The pathway of leucine to mevalonate, which has attracted attention in the study of the biosynthesis of isoprenoid in parasitic protozoa and myxobacterium, was observed in the biosynthesis of the lipid core in halophilic archaea. The involvement of isovaleryl-CoA dehydrogenase was strongly suggested, with stereospecific conversion of the diastereotopic methyl group of leucine to isoprenoidal lipid.

  9. Hypothalamic dysfunction without hamartomas causing gelastic seizures in optic nerve hypoplasia.

    PubMed

    Fink, Cassandra; Borchert, Mark; Simon, Carrie Zaslow; Saper, Clifford

    2015-02-01

    This report describes gelastic seizures in patients with optic nerve hypoplasia and hypothalamic dysfunction without hypothalamic hamartoma. All participants (n = 4) from the optic nerve hypoplasia registry study at Children's Hospital Los Angeles presenting with gelastic seizures were included. The clinical and pathology characteristics include hypothalamic dysgenesis and dysfunction, but no hamartomas. Optic nerve hypoplasia is the only reported condition with gelastic seizures without hypothalamic hamartomas, suggesting that hypothalamic disorganization alone can cause gelastic seizures.

  10. Hypothalamic obesity in children: pathophysiology to clinical management.

    PubMed

    Haliloglu, Belma; Bereket, Abdullah

    2015-05-01

    Hypothalamic obesity (HyOb) is a complex neuroendocrine disorder caused by damage to the hypothalamus, which results in disruption of energy regulation. The key hypothalamic areas of energy regulation are the ARC (arcuate nucleus), the VMH (ventromedial hypothalamus), the PVN (paraventriculer nuclei) and the LHA (lateral hypothalamic area). These pathways can be disrupted mechanically by hypothalamic tumors, neurosurgery, inflammatory disorders, radiotherapy and trauma or functionally as such seen in genetic diseases. Rapid weight gain and severe obesity are the most striking features of HyOb and caused by hyperphagia, reduced basal metabolic rate (BMR) and decreased physical activity. HyOb is usually unresponsive to diet and exercise. Although, GLP-1 and its anologs seem to be a new agent, there is still no curative treatment. Thus, prevention is of prime importance and the clinicians should be alert and vigilant in patients at risk for development of HyOb.

  11. Delineating the regulation of energy homeostasis using hypothalamic cell models.

    PubMed

    Wellhauser, Leigh; Gojska, Nicole M; Belsham, Denise D

    2015-01-01

    Attesting to its intimate peripheral connections, hypothalamic neurons integrate nutritional and hormonal cues to effectively manage energy homeostasis according to the overall status of the system. Extensive progress in the identification of essential transcriptional and post-translational mechanisms regulating the controlled expression and actions of hypothalamic neuropeptides has been identified through the use of animal and cell models. This review will introduce the basic techniques of hypothalamic investigation both in vivo and in vitro and will briefly highlight the key advantages and challenges of their use. Further emphasis will be place on the use of immortalized models of hypothalamic neurons for in vitro study of feeding regulation, with a particular focus on cell lines proving themselves most fruitful in deciphering fundamental basics of NPY/AgRP, Proglucagon, and POMC neuropeptide function. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Metabolism and acetylation contribute to leucine-mediated inhibition of cardiac glucose uptake.

    PubMed

    Renguet, Edith; Ginion, Audrey; Gélinas, Roselle; Bultot, Laurent; Auquier, Julien; Robillard Frayne, Isabelle; Daneault, Caroline; Vanoverschelde, Jean-Louis; Des Rosiers, Christine; Hue, Louis; Horman, Sandrine; Beauloye, Christophe; Bertrand, Luc

    2017-08-01

    High plasma leucine levels strongly correlate with type 2 diabetes. Studies of muscle cells have suggested that leucine alters the insulin response for glucose transport by activating an insulin-negative feedback loop driven by the mammalian target of rapamycin/p70 ribosomal S6 kinase (mTOR/p70S6K) pathway. Here, we examined the molecular mechanism involved in leucine's action on cardiac glucose uptake. Leucine was indeed able to curb glucose uptake after insulin stimulation in both cultured cardiomyocytes and perfused hearts. Although leucine activated mTOR/p70S6K, the mTOR inhibitor rapamycin did not prevent leucine's inhibitory action on glucose uptake, ruling out the contribution of the insulin-negative feedback loop. α-Ketoisocaproate, the first metabolite of leucine catabolism, mimicked leucine's effect on glucose uptake. Incubation of cardiomyocytes with [(13)C]leucine ascertained its metabolism to ketone bodies (KBs), which had a similar negative impact on insulin-stimulated glucose transport. Both leucine and KBs reduced glucose uptake by affecting translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Finally, we found that leucine elevated the global protein acetylation level. Pharmacological inhibition of lysine acetyltransferases counteracted this increase in protein acetylation and prevented leucine's inhibitory action on both glucose uptake and GLUT4 translocation. Taken together, these results indicate that leucine metabolism into KBs contributes to inhibition of cardiac glucose uptake by hampering the translocation of GLUT4-containing vesicles via acetylation. They offer new insights into the establishment of insulin resistance in the heart.NEW & NOTEWORTHY Catabolism of the branched-chain amino acid leucine into ketone bodies efficiently inhibits cardiac glucose uptake through decreased translocation of glucose transporter 4 to the plasma membrane. Leucine increases protein acetylation. Pharmacological inhibition of acetylation

  13. Rapid-onset obesity, hypoventilation, hypothalamic dysfunction, autonomic dysregulation syndrome.

    PubMed

    Maksoud, Ismaeil; Kassab, Lina

    2015-01-01

    Rapid-onset obesity with hypoventilation, hypothalamic dysfunction and autonomic dysregulation syndrome is a rare disorder that presents with rapidly evolving obesity with several endocrine disorders during early childhood. We present here a documented case of a 6-year-old Syrian girl with the characteristic symptoms of rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation, associated with an abdominal mass (mature ganglioneuroma).

  14. Rapid-onset obesity, hypoventilation, hypothalamic dysfunction, autonomic dysregulation syndrome

    PubMed Central

    Maksoud, Ismaeil; Kassab, Lina

    2015-01-01

    Rapid-onset obesity with hypoventilation, hypothalamic dysfunction and autonomic dysregulation syndrome is a rare disorder that presents with rapidly evolving obesity with several endocrine disorders during early childhood. We present here a documented case of a 6-year-old Syrian girl with the characteristic symptoms of rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation, associated with an abdominal mass (mature ganglioneuroma). PMID:26229761

  15. Leucine metabolism in regulation of insulin secretion from pancreatic beta cells

    PubMed Central

    Yang, Jichun; Chi, Yujing; Burkhardt, Brant R.; Guan, Youfei; Wolf, Bryan A

    2010-01-01

    Leucine, a the branched-chain amino acids that must be supplied in daily diet, plays an important role in controlling protein synthesis and regulating cell metabolism in various cell types. In pancreatic β cells, leucine acutely stimulates insulin secretion by serving as both metabolic fuel and allosteric activator of glutamate dehydrogenase to enhance glutaminolysis. Leucine has also been shown to regulate gene transcription and protein synthesis in pancreatic islet β cells via both mTOR-dependent and -independent pathways at physiological concentrations. Long-term treatment of leucine has been shown to improve insulin secretory dysfunction of human diabetic islets via upregulation of certain key metabolic genes. In vivo, leucine administration improves glycemic control in humans and rodents with type 2 diabetes. This review aims to summarize and discuss the recent findings regarding the effects of leucine metabolism on pancreatic β cell function. PMID:20500788

  16. Comparison of the fates of ingested leucine and ingested 2-ketoisocaproate in rats

    SciTech Connect

    Imura, K.; Walser, M. )

    1990-05-01

    We previously reported that the ratio, R, of 14C to 3H in the leucine of whole body protein, measured 6 h after ingestion of (3H)leucine and (1-14C)2-ketoisocaproate is equal to ratio of the dose of leucine to the dose of 2-ketoisocaproate (KIC) (on a leucine-free diet) required to achieve the same rate of growth. To determine whether R is dependent on the interval between injection and sampling, R was measured at intervals in purified whole body protein after oral injection of these isotopes in groups of rats; it was constant from 1 h onward for 1 wk, averaging 0.64 +/- 0.01 (means +/- SEM). Thus, the extent of incorporation into the leucine of whole body protein of ingested KIC remains close to 64% of the incorporation of ingested leucine administered as such simultaneously, from 1 h onward for at least 1 wk.

  17. Sestrin2 is a leucine sensor for the mTORC1 pathway.

    PubMed

    Wolfson, Rachel L; Chantranupong, Lynne; Saxton, Robert A; Shen, Kuang; Scaria, Sonia M; Cantor, Jason R; Sabatini, David M

    2016-01-01

    Leucine is a proteogenic amino acid that also regulates many aspects of mammalian physiology, in large part by activating the mTOR complex 1 (mTORC1) protein kinase, a master growth controller. Amino acids signal to mTORC1 through the Rag guanosine triphosphatases (GTPases). Several factors regulate the Rags, including GATOR1, aGTPase-activating protein; GATOR2, a positive regulator of unknown function; and Sestrin2, a GATOR2-interacting protein that inhibits mTORC1 signaling. We find that leucine, but not arginine, disrupts the Sestrin2-GATOR2 interaction by binding to Sestrin2 with a dissociation constant of 20 micromolar, which is the leucine concentration that half-maximally activates mTORC1. The leucine-binding capacity of Sestrin2 is required for leucine to activate mTORC1 in cells. These results indicate that Sestrin2 is a leucine sensor for the mTORC1 pathway.

  18. Pure endoscopic management of epileptogenic hypothalamic hamartomas.

    PubMed

    Chibbaro, S; Cebula, H; Scholly, J; Todeschi, J; Ollivier, I; Timofeev, A; Ganau, M; Di Emidio, P; Valenti, M P; Staack, A M; Bast, T; Steinhoff, B J; Hirsch, E; Kehrli, P; Proust, F

    2017-02-07

    Hypothalamic hamartomas (HH) are rare congenital malformations located in the region of the tuber cinereum and third ventricle. Their usual clinical presentation is characterized by gelastic/dacrystic seizures which often become pharmaco-resistant and progress to secondary focal/generalized intractable epilepsy causing mostly in children cognitive and behavioral problems (particularly in cases of progressive epileptic encephalopathy) and precocious puberty. Whereas gelastic seizures can be surgically controlled either by resection of the lesion or disconnection (tissue-destructive) procedures, aimed at functionally prevent the spreading of the epileptic burst; generalized seizures tend to respond better to HH excision rather than isolated neocortical resections, which generally fail to control them. Prospective analysis of 14 consecutive patients harboring HH treated in an 8-year period; 12 patients had unilateral and two bilateral HH. All patients were managed by pure endoscopic excision of the HH. The mean operative time was 48 min and mean hospital stay was 2 days; perioperative blood loss was negligible in all cases. Two patients showed a transient diabetes insipidus (DI); no transient or permanent postoperative neurological deficit or memory impairment was recorded. Complete HH excision was achieved in 10/14 patients. At a mean follow-up of 48 months, no wound infection, meningitis, postoperative hydrocephalus, and/or mortality were recorded in this series of patients. Eight patients became seizure free (Engel class I), 2 other experienced worthwhile improvement of disabling seizures (Engel class II); 2 patients were cured from gelastic attacks while still experiencing focal dyscognitive seizures; and 2, having bilateral HH (both undergoing unilateral HH excision), did not experience significant improvement and required later on a temporal lobectomy coupled to amygdalohyppocampectomy. Overall, the followings resulted to be predictive factors for better

  19. Hypothalamic germinoma masquerading as superior mesenteric artery (SMA) syndrome.

    PubMed

    Vethakkan, Shireene R; Venugopal, Yogeswari; Tan, Alexander T B; Paramasivam, Sharmila S; Ratnasingam, Jeyakantha; Razak, Rohaya A; Alias, Azmi; Kassim, Fauziah; Choong, Karen

    2013-01-01

    To report a case of superior mesenteric artery (SMA) syndrome secondary to hypothalamic germinoma. We describe the clinical presentation, diagnostic work-up, management, and clinical course of a patient admitted with SMA syndrome who was subsequently found to have a hypothalamic germinoma. An adolescent boy was admitted to the surgical ward with progressive weight loss over a 2 year period and postprandial vomiting. He was diagnosed with SMA syndrome based on evidence of proximal duodenal dilatation, extrinsic compression of the distal duodenum, and a narrowed aortomesenteric angle (16°). Investigations performed to exclude thyrotoxicosis unexpectedly revealed secondary hypothyroidism and further evaluation demonstrated evidence of pan-hypopituitarism. Psychiatric evaluation excluded anorexia nervosa and bulimia. Magnetic resonance imaging (MRI) of the brain revealed a heterogeneously enhancing hypothalamic lesion, but a normal pituitary gland. Hormone replacement with hydrocortisone, desmopressin, testosterone, and thyroxine resulted in weight gain and resolution of gastrointestinal symptoms. A transventricular endoscopic biopsy subsequently confirmed a hypothalamic germinoma and he was referred to an oncologist. SMA syndrome secondary to severe weight loss is an uncommon cause of upper gastrointestinal obstruction. While there have been reports of poorly controlled diabetes mellitus and thyrotoxicosis manifesting as SMA syndrome, there are no published reports to date of SMA syndrome secondary to hypothalamic/pituitary disease. Management of SMA syndrome is conservative, as symptoms of intestinal obstruction resolve with weight gain following treatment of the underlying cause. Awareness of this uncommon presentation of endocrine cachexia/hypothalamic disease will prevent unnecessary laparotomies and a misdiagnosis of an eating disorder.

  20. Knockout of leucine aminopeptidase in Toxoplasma gondii using CRISPR/Cas9.

    PubMed

    Zheng, Jun; Jia, Honglin; Zheng, Yonghui

    2015-02-01

    Leucine aminopeptidases of the M17 peptidase family represent ideal drug targets for therapies directed against the pathogens Plasmodium, Babesia and Trypanosoma. Previously, we characterised Toxoplasma gondii leucine aminopeptidase and demonstrated its role in regulating the levels of free amino acids. In this study, we evaluated the potential of T. gondii leucine aminopeptidase as a drug target in T. gondii by a knockout method. Existing knockout methods for T. gondii have many drawbacks; therefore, we developed a new technique that takes advantage of the CRISPR/Cas9 system. We first chose a Cas9 target site in the gene encoding T. gondii leucine aminopeptidase and then constructed a knockout vector containing Cas9 and the single guide RNA. After transfection, single tachyzoites were cloned in 96-well plates by limiting dilution. Two transfected strains derived from a single clone were cultured in Vero cells, and then subjected to expression analysis by western blotting. The phenotypic analysis revealed that knockout of T. gondii leucine aminopeptidase resulted in inhibition of attachment/invasion and replication; both the growth and attachment/invasion capacity of knockout parasites were restored by complementation with a synonymously substituted allele of T. gondii leucine aminopeptidase. Mouse experiments demonstrated that T. gondii leucine aminopeptidase knockout somewhat reduced the pathogenicity of T. gondii. An enzymatic activity assay showed that T. gondii leucine aminopeptidase knockout reduced the processing of a leucine aminopeptidase-specific substrate in T. gondii. The absence of leucine aminopeptidase activity could be slightly compensated for in T. gondii. Overall, T. gondii leucine aminopeptidase knockout influenced the growth of T. gondii, but did not completely block parasite development, virulence or enzymatic activity. Therefore, we conclude that leucine aminopeptidase would be useful only as an adjunctive drug target in T. gondii. Copyright

  1. The retro-GCN4 leucine zipper sequence forms a stable three-dimensional structure

    PubMed Central

    Mittl, Peer R. E.; Deillon, Christine; Sargent, David; Liu, Niankun; Klauser, Stephan; Thomas, Richard M.; Gutte, Bernd; Grütter, Markus G.

    2000-01-01

    The question of whether a protein whose natural sequence is inverted adopts a stable fold is still under debate. We have determined the 2.1-Å crystal structure of the retro-GCN4 leucine zipper. In contrast to the two-stranded helical coiled-coil GCN4 leucine zipper, the retro-leucine zipper formed a very stable, parallel four-helix bundle, which now lends itself to further structural and functional studies. PMID:10716989

  2. Kinetics and conformational stability studies of recombinant leucine aminopeptidase.

    PubMed

    Hernández-Moreno, Ana V; Villaseñor, Francisco; Medina-Rivero, Emilio; Pérez, Néstor O; Flores-Ortiz, Luis F; Saab-Rincón, Gloria; Luna-Bárcenas, Gabriel

    2014-03-01

    Leucine aminopeptidase from Vibrio proteolyticus is a broad specificity N-terminal aminopeptidase that is widely used in pharmaceutical processes where the removal of N-terminal residues in recombinant proteins is required. We previously reported the expression of a heterologous construction of the mature protein fused to a 6-histidine tag that presents a reasonable refolding rate for its use at industrial level. Here, we investigate this recombinant leucine aminopeptidase (rLAP) to explain the gain of activity observed when incubated at 37 °C after its production. Unfolding transitions of rLAP as a function of urea concentration were monitored by circular dichroism (CD) and fluorescence (FL) spectroscopy exhibiting single transitions by both techniques. Free energy change for unfolding measured by CD and FL spectroscopy are 2.8 ± 0.4 and 3.7 ± 0.4 kcal mol(-1), respectively. Thermal stability conformation of rLAP is 2.6 ± 0.1 and 6.1 kcal mol(-1) for CD and Nano-Differential Scanning Calorimetry (Nano-DSC), respectively. Enzyme activity was assessed with L-leucine-p-nitroanilide (L-pNA) as substrate. The catalytic efficiency was 3.87 ± 0.10 min(-1) μM(-1) at 37 °C and pH 8.0. Kinetic and conformation studies show differences between the enzyme native and rLAP; however rLAP is selective and specific to remove N-terminal groups from amino acids.

  3. Novel leucine ureido derivatives as inhibitors of aminopeptidase N (APN).

    PubMed

    Ma, Chunhua; Jin, Kang; Cao, Jiangying; Zhang, Lei; Li, Xiaoguang; Xu, Wenfang

    2013-04-01

    Aminopeptidase N (APN/CD13) over expressed on tumor cells, plays a critical role in tumor invasion, metastasis, and tumor angiogenesis. Here we described the design, synthesis and preliminary activity studies of novel leucine ureido derivatives as aminopeptidase N (APN/CD13) inhibitors. The results showed that compound 8c had the most potent inhibitory activity against APN with the IC50 value to 0.06 ± 0.041 μM, which could be used for further anticancer agent research.

  4. Histochemistry of leucine aminoaphthylamidase (LAN) in rainbow trout (Salmo gairdneri)

    USGS Publications Warehouse

    Bouck, Gerald R.

    1979-01-01

    The histochemistry of leucine aminonaphthylamidase (LAN) was studied in frozen tissue sections of rainbow trout both in yearling and adult fish. Age of fish had relatively little effect upon the results. The most intense LAN color production was in epithelial cells of midgut, pyloric ceca, hindgut, and in some segments of kidney tubules. Lower levels of LAN were evident in liver cells of Kupffer, and still lower or slight levels of LAN activity were found in blood cells, muscle, nerve, connective tissue, gonad, and pancreas. The results indicate that LAN might be useful in assessing histotoxicity to LAN-rich areas of the body.

  5. Histochemistry of leucine aminonaphthylamidase (LAN) in rainbow trout (Salmo gairdneri)

    USGS Publications Warehouse

    Bouck, Gerald R.

    1979-01-01

    The histochemistry of leucine aminonaphthylamidase (LAN) was studied in frozen tissue sections of rainbow trout both in yearling and adult fish. Age of fish had relatively little effect upon the results. The most intense LAN color production was in epithelial cells of midgut, pyloric ceca, hindgut, and in some segments of kidney tubules. Lower levels of LAN were evident in liver cells of Kupffer, and still lower or slight levels of LAN activity were found in blood cells, muscle, nerve, connective tissue, gonad, and pancreas. The results indicate that LAN might be useful in assessing histotoxicity to LAN-rich areas of the body.

  6. Acetone formation in the Vibrio family: a new pathway for bacterial leucine catabolism.

    PubMed

    Nemecek-Marshall, M; Wojciechowski, C; Wagner, W P; Fall, R

    1999-12-01

    There is current interest in biological sources of acetone, a volatile organic compound that impacts atmospheric chemistry. Here, we determined that leucine-dependent acetone formation is widespread in the Vibrionaceae. Sixteen Vibrio isolates, two Listonella species, and two Photobacterium angustum isolates produced acetone in the presence of L-leucine. Shewanella isolates produced much less acetone. Growth of Vibrio splendidus and P. angustum in a fermentor with controlled aeration revealed that acetone was produced after a lag in late logarithmic or stationary phase of growth, depending on the medium, and was not derived from acetoacetate by nonenzymatic decarboxylation in the medium. L-Leucine, but not D-leucine, was converted to acetone with a stoichiometry of approximately 0.61 mol of acetone per mol of L-leucine. Testing various potential leucine catabolites as precursors of acetone showed that only alpha-ketoisocaproate was efficiently converted by whole cells to acetone. Acetone production was blocked by a nitrogen atmosphere but not by electron transport inhibitors, suggesting that an oxygen-dependent reaction is required for leucine catabolism. Metabolic labeling with deuterated (isopropyl-d(7))-L-leucine revealed that the isopropyl carbons give rise to acetone with full retention of deuterium in each methyl group. These results suggest the operation of a new catabolic pathway for leucine in vibrios that is distinct from the 3-hydroxy-3-methylglutaryl-coenzyme A pathway seen in pseudomonads.

  7. Specificity of the effects of leucine and its metabolites on protein degradation in skeletal muscle.

    PubMed Central

    Mitch, W E; Clark, A S

    1984-01-01

    The effects of leucine, its metabolites, and the 2-oxo acids of valine and isoleucine on protein synthesis and degradation in incubated limb muscles of immature and adult rats were tested. Leucine stimulated protein synthesis but did not reduce proteolysis when leucine transamination was inhibited. 4-Methyl-2-oxopentanoate at concentrations as low as 0.25 mM inhibited protein degradation but did not change protein synthesis. The 2-oxo acids of valine and isoleucine did not change protein synthesis or degradation even at concentrations as high as 5 mM. 3-Methylvalerate, the irreversibly decarboxylated product of 4-methyl-2-oxopentanoate, decreased protein degradation at concentrations greater than or equal to 1 mM. This was not due to inhibition of 4-methyl-2-oxopentanoate catabolism, because 0.5 mM-3-methylvalerate did not suppress proteolysis, even though it inhibited leucine decarboxylation by 30%; higher concentrations of 3-methylvalerate decreased proteolysis progressively without inhibiting leucine decarboxylation further. During incubation with [1-14C]- and [U-14C]-leucine, it was found that products of leucine catabolism formed subsequent to the decarboxylation of 4-methyl-2-oxopentanoate accumulated intracellularly. This pattern was not seen during incubation with radiolabelled valine. Thus, the effect of leucine on muscle proteolysis requires transamination to 4-methyl-2-oxopentanoate. The inhibition of muscle protein degradation by leucine is most sensitive to, but not specific for, its 2-oxo acid, 4-methyl-2-oxopentanoate. PMID:6487265

  8. Acetone Formation in the Vibrio Family: a New Pathway for Bacterial Leucine Catabolism

    PubMed Central

    Nemecek-Marshall, Michele; Wojciechowski, Cheryl; Wagner, William P.; Fall, Ray

    1999-01-01

    There is current interest in biological sources of acetone, a volatile organic compound that impacts atmospheric chemistry. Here, we determined that leucine-dependent acetone formation is widespread in the Vibrionaceae. Sixteen Vibrio isolates, two Listonella species, and two Photobacterium angustum isolates produced acetone in the presence of l-leucine. Shewanella isolates produced much less acetone. Growth of Vibrio splendidus and P. angustum in a fermentor with controlled aeration revealed that acetone was produced after a lag in late logarithmic or stationary phase of growth, depending on the medium, and was not derived from acetoacetate by nonenzymatic decarboxylation in the medium. l-Leucine, but not d-leucine, was converted to acetone with a stoichiometry of approximately 0.61 mol of acetone per mol of l-leucine. Testing various potential leucine catabolites as precursors of acetone showed that only α-ketoisocaproate was efficiently converted by whole cells to acetone. Acetone production was blocked by a nitrogen atmosphere but not by electron transport inhibitors, suggesting that an oxygen-dependent reaction is required for leucine catabolism. Metabolic labeling with deuterated (isopropyl-d7)-l-leucine revealed that the isopropyl carbons give rise to acetone with full retention of deuterium in each methyl group. These results suggest the operation of a new catabolic pathway for leucine in vibrios that is distinct from the 3-hydroxy-3-methylglutaryl-coenzyme A pathway seen in pseudomonads. PMID:10601206

  9. Simultaneous synthesis and coating of salbutamol sulphate nanoparticles with L-leucine in the gas phase.

    PubMed

    Lähde, Anna; Raula, Janne; Kauppinen, Esko I

    2008-06-24

    Salbutamol sulphate nanoparticles have been simultaneously prepared and coated with L-leucine in the gas phase. Three different ways of coating can be separated based on the operation temperatures used in an aerosol flow reactor. Below the temperature of L-leucine sublimation, formation of the L-leucine layer on the core particle surface takes place via diffusion of L-leucine molecules on the droplet surfaces during droplet drying. At intermediate temperatures, the extent of sublimation of L-leucine depends notably on the concentration, and thus partial evaporation was expected. The L-leucine coating was solely formed via vapor deposition at high reactor temperatures when complete sublimation of L-leucine was obtained. The geometric mean diameter of the core salbutamol particles was approximately 65 nm. In general, particle size increased with the addition of L-leucine. The size distribution remained the same or broadened when the coating layer of the particles was formed via surface diffusion whereas notable narrowing of the distribution was observed when the coating was formed via vapor deposition. Upon desublimation and heterogeneous nucleation on the surfaces of smooth, spherical core particles, L-leucine formed a discontinuous coating with leafy crystals a few nanometers in size.

  10. The Leucine Incorporation Method Estimates Bacterial Growth Equally Well in Both Oxic and Anoxic Lake Waters

    PubMed Central

    Bastviken, David; Tranvik, Lars

    2001-01-01

    Bacterial biomass production is often estimated from incorporation of radioactively labeled leucine into protein, in both oxic and anoxic waters and sediments. However, the validity of the method in anoxic environments has so far not been tested. We compared the leucine incorporation of bacterial assemblages growing in oxic and anoxic waters from three lakes differing in nutrient and humic contents. The method was modified to avoid O2 contamination by performing the incubation in syringes. Isotope saturation levels in oxic and anoxic waters were determined, and leucine incorporation rates were compared to microscopically observed bacterial growth. Finally, we evaluated the effects of O2 contamination during incubation with leucine, as well as the potential effects of a headspace in the incubation vessel. Isotope saturation occurred at a leucine concentration of above about 50 nM in both oxic and anoxic waters from all three lakes. Leucine incorporation rates were linearly correlated to observed growth, and there was no significant difference between oxic and anoxic conditions. O2 contamination of anoxic water during 1-h incubations with leucine had no detectable impact on the incorporation rate, while a headspace in the incubation vessel caused leucine incorporation to increase in both anoxic and O2-contaminated samples. The results indicate that the leucine incorporation method relates equally to bacterial growth rates under oxic and anoxic conditions and that incubation should be performed without a headspace. PMID:11425702

  11. "Leucine aminopeptidase" (neutral arylamidase) in sheep sera: improved resolution with gradient gel electrophoresis.

    PubMed

    Manwell, C; Baker, C M

    1986-01-01

    Electrophoretic resolution of the heterogeneity of sheep serum "leucine aminopeptidase" is greatly improved by the use of gradients of acrylamide polymer, together with enzyme localisation involving L-alanyl beta-naphthylamide and cobaltous ion. The improved resolution contradicts an earlier claim of the existence of only two patterns of individual variation in the heterogeneity of sheep serum "leucine aminopeptidase", with one pattern completely dominant to the other. While the sheep enzyme is unusual among mammalian serum "leucine aminopeptidases" in its complex heterogeneity, it does conform to the typical mammalian pattern of codominant individual variation. The complexity of sheep serum "leucine aminopeptidase" is useful in the study of sheep evolution.

  12. Hypothalamic-pituitary-adrenocortical axis: neuropsychiatric aspects.

    PubMed

    Jacobson, Lauren

    2014-04-01

    Evidence of aberrant hypothalamic-pituitary-adrenocortical (HPA) activity in many psychiatric disorders, although not universal, has sparked long-standing interest in HPA hormones as biomarkers of disease or treatment response. HPA activity may be chronically elevated in melancholic depression, panic disorder, obsessive-compulsive disorder, and schizophrenia. The HPA axis may be more reactive to stress in social anxiety disorder and autism spectrum disorders. In contrast, HPA activity is more likely to be low in PTSD and atypical depression. Antidepressants are widely considered to inhibit HPA activity, although inhibition is not unanimously reported in the literature. There is evidence, also uneven, that the mood stabilizers lithium and carbamazepine have the potential to augment HPA measures, while benzodiazepines, atypical antipsychotics, and to some extent, typical antipsychotics have the potential to inhibit HPA activity. Currently, the most reliable use of HPA measures in most disorders is to predict the likelihood of relapse, although changes in HPA activity have also been proposed to play a role in the clinical benefits of psychiatric treatments. Greater attention to patient heterogeneity and more consistent approaches to assessing treatment effects on HPA function may solidify the value of HPA measures in predicting treatment response or developing novel strategies to manage psychiatric disease. © 2014 American Physiological Society.

  13. Hypothalamic PKA regulates leptin sensitivity and adiposity

    PubMed Central

    Yang, Linghai; McKnight, G. Stanley

    2015-01-01

    Mice lacking the RIIβ regulatory subunit of cyclic AMP-dependent protein kinase A (PKA) display reduced adiposity and resistance to diet-induced obesity. Here we show that RIIβ knockout (KO) mice have enhanced sensitivity to leptin's effects on both feeding and energy metabolism. After administration of a low dose of leptin, the duration of hypothalamic JAK/STAT3 signalling is increased, resulting in enhanced POMC mRNA induction. Consistent with the extended JAK/STAT3 activation, we find that the negative feedback regulator of leptin receptor signalling, Socs3, is inhibited in the hypothalamus of RIIβ KO mice. During fasting, RIIβ–PKA is activated and this correlates with an increase in CREB phosphorylation. The increase in CREB phosphorylation is absent in the fasted RIIβ KO hypothalamus. Selective inhibition of PKA activity in AgRP neurons partially recapitulates the leanness and resistance to diet-induced obesity of RIIβ KO mice. Our findings suggest that RIIβ–PKA modulates the duration of leptin receptor signalling and therefore the magnitude of the catabolic response to leptin. PMID:26381935

  14. Hypothalamic dopaminergic stimulation in cluster headache.

    PubMed

    Lepper, Anne; Frese, Achim; Summ, Oliver; Nofer, Jerzy-Roch; Evers, Stefan

    2013-10-01

    Cluster headache is associated with structural abnormalities of the hypothalamus. We were interested in the association of cluster headache with endocrinological functional abnormalities. Therefore, we applied the apomorphine challenge test, which is a specific test of hypothalamic dopaminergic activation. We enrolled 13 patients with cluster headache outside the bout and without medication. They were stimulated with 0.005 mg/kg of body weight subcutaneous apomorphine hydrochloride. After 45 and 60 minutes, growth hormone (GH), prolactin and cortisol were measured. The test was also applied to 14 sex- and age-matched healthy control subjects. There were significantly higher GH levels in healthy subjects as compared to cluster headache patients 45 minutes after injection (10.8 ± 10.8 versus 4.4 ± 7.4 ng/ml; P  = 0.038). Only in cluster headache, the GH level after 60 minutes was not significantly different from the baseline. The levels of prolactin and cortisol did not show any significant differences between cluster headache patients and in healthy subjects. Our data suggest that cluster headache is associated with an impaired dopaminergic stimulation. This finding supports the body of evidence that cluster headache is associated with a functional abnormality of the hypothalamus and that this association is a primary (i.e. idiopathic) and not a secondary phenomenon during the bout.

  15. Hypothalamic control of brown adipose tissue thermogenesis

    PubMed Central

    Labbé, Sebastien M.; Caron, Alexandre; Lanfray, Damien; Monge-Rofarello, Boris; Bartness, Timothy J.; Richard, Denis

    2015-01-01

    It has long been known, in large part from animal studies, that the control of brown adipose tissue (BAT) thermogenesis is insured by the central nervous system (CNS), which integrates several stimuli in order to control BAT activation through the sympathetic nervous system (SNS). SNS-mediated BAT activity is governed by diverse neurons found in brain structures involved in homeostatic regulations and whose activity is modulated by various factors including oscillations of energy fluxes. The characterization of these neurons has always represented a challenging issue. The available literature suggests that the neuronal circuits controlling BAT thermogenesis are largely part of an autonomic circuitry involving the hypothalamus, brainstem and the SNS efferent neurons. In the present review, we recapitulate the latest progresses in regards to the hypothalamic regulation of BAT metabolism. We briefly addressed the role of the thermoregulatory pathway and its interactions with the energy balance systems in the control of thermogenesis. We also reviewed the involvement of the brain melanocortin and endocannabinoid systems as well as the emerging role of steroidogenic factor 1 (SF1) neurons in BAT thermogenesis. Finally, we examined the link existing between these systems and the homeostatic factors that modulate their activities. PMID:26578907

  16. Hypothalamic effects of thyroid hormones on metabolism.

    PubMed

    Martínez-Sánchez, Noelia; Alvarez, Clara V; Fernø, Johan; Nogueiras, Rubén; Diéguez, Carlos; López, Miguel

    2014-10-01

    Over the past few decades, obesity and its related metabolic disorders have increased at an epidemic rate in the developed and developing world. New signals and factors involved in the modulation of energy balance and metabolism are continuously being discovered, providing potential novel drug targets for the treatment of metabolic disease. A parallel strategy is to better understand how hormonal signals, with an already established role in energy metabolism, work, and how manipulation of the pathways involved may lead to amelioration of metabolic dysfunction. The thyroid hormones belong to the latter category, with dysregulation of the thyroid axis leading to marked alterations in energy balance. The potential of thyroid hormones in the treatment of obesity has been known for decades, but their therapeutic use has been hampered because of side-effects. Data gleaned over the past few years, however, have uncovered new features at the mechanisms of action involved in thyroid hormones. Sophisticated neurobiological approaches have allowed the identification of specific energy sensors, such as AMP-activated protein kinase and mechanistic target of rapamycin, acting in specific groups of hypothalamic neurons, mediating many of the effects of thyroid hormones on food intake, energy expenditure, glucose, lipid metabolism, and cardiovascular function. More extensive knowledge about these molecular mechanisms will be of great relevance for the treatment of obesity and metabolic syndrome.

  17. Paraventricular Hypothalamic Mechanisms of Chronic Stress Adaptation

    PubMed Central

    Herman, James P.; Tasker, Jeffrey G.

    2016-01-01

    The hypothalamic paraventricular nucleus (PVN) is the primary driver of hypothalamo–pituitary–adrenocortical (HPA) responses. At least part of the role of the PVN is managing the demands of chronic stress exposure. With repeated exposure to stress, hypophysiotrophic corticotropin-releasing hormone (CRH) neurons of the PVN display a remarkable cellular, synaptic, and connectional plasticity that serves to maximize the ability of the HPA axis to maintain response vigor and flexibility. At the cellular level, chronic stress enhances the production of CRH and its co-secretagogue arginine vasopressin and rearranges neurotransmitter receptor expression so as to maximize cellular excitability. There is also evidence to suggest that efficacy of local glucocorticoid feedback is reduced following chronic stress. At the level of the synapse, chronic stress enhances cellular excitability and reduces inhibitory tone. Finally, chronic stress causes a structural enhancement of excitatory innervation, increasing the density of glutamate and noradrenergic/adrenergic terminals on CRH neuronal cell somata and dendrites. Together, these neuroplastic changes favor the ability of the HPA axis to retain responsiveness even under conditions of considerable adversity. Thus, chronic stress appears able to drive PVN neurons via a number of convergent mechanisms, processes that may play a major role in HPA axis dysfunction seen in variety of stress-linked disease states. PMID:27843437

  18. Fatty Acid Transporter CD36 Mediates Hypothalamic Effect of Fatty Acids on Food Intake in Rats

    PubMed Central

    Moullé, Valentine S.; Le Foll, Christelle; Philippe, Erwann; Kassis, Nadim; Rouch, Claude; Marsollier, Nicolas; Bui, Linh-Chi; Guissard, Christophe; Dairou, Julien; Lorsignol, Anne; Pénicaud, Luc; Levin, Barry E.; Cruciani-Guglielmacci, Céline; Magnan, Christophe

    2013-01-01

    Variations in plasma fatty acid (FA) concentrations are detected by FA sensing neurons in specific brain areas such as the hypothalamus. These neurons play a physiological role in the control of food intake and the regulation of hepatic glucose production. Le Foll et al. previously showed in vitro that at least 50% of the FA sensing in ventromedial hypothalamic (VMH) neurons is attributable to the interaction of long chain FA with FA translocase/CD36 (CD36). The present work assessed whether in vivo effects of hypothalamic FA sensing might be partly mediated by CD36 or intracellular events such as acylCoA synthesis or β-oxidation. To that end, a catheter was implanted in the carotid artery toward the brain in male Wistar rats. After 1 wk recovery, animals were food-deprived for 5 h, then 10 min infusions of triglyceride emulsion, Intralipid +/− heparin (IL, ILH, respectively) or saline/heparin (SH) were carried out and food intake was assessed over the next 5 h. Experimental groups included: 1) Rats previously injected in ventromedian nucleus (VMN) with shRNA against CD36 or scrambled RNA; 2) Etomoxir (CPT1 inhibitor) or saline co-infused with ILH/SH; and 3) Triacsin C (acylCoA synthase inhibitor) or saline co-infused with ILH/SH. ILH significantly lowered food intake during refeeding compared to SH (p<0.001). Five hours after refeeding, etomoxir did not affect this inhibitory effect of ILH on food intake while VMN CD36 depletion totally prevented it. Triacsin C also prevented ILH effects on food intake. In conclusion, the effect of FA to inhibit food intake is dependent on VMN CD36 and acylCoA synthesis but does not required FA oxidation. PMID:24040150

  19. Comparative analysis of pharmacological treatments with N-acetyl-DL-leucine (Tanganil) and its two isomers (N-acetyl-L-leucine and N-acetyl-D-leucine) on vestibular compensation: Behavioral investigation in the cat.

    PubMed

    Tighilet, Brahim; Leonard, Jacques; Bernard-Demanze, Laurence; Lacour, Michel

    2015-12-15

    Head roll tilt, postural imbalance and spontaneous nystagmus are the main static vestibular deficits observed after an acute unilateral vestibular loss (UVL). In the UVL cat model, these deficits are fully compensated over 6 weeks as the result of central vestibular compensation. N-Acetyl-dl-leucine is a drug prescribed in clinical practice for the symptomatic treatment of acute UVL patients. The present study investigated the effects of N-acetyl-dl-leucine on the behavioral recovery after unilateral vestibular neurectomy (UVN) in the cat, and compared the effects of each of its two isomers N-acetyl-L-leucine and N-acetyl-D-leucine. Efficacy of these three drug treatments has been evaluated with respect to a placebo group (UVN+saline water) on the global sensorimotor activity (observation grids), the posture control (support surface measurement), the locomotor balance (maximum performance at the rotating beam test), and the spontaneous vestibular nystagmus (recorded in the light). Whatever the parameters tested, the behavioral recovery was strongly and significantly accelerated under pharmacological treatments with N-acetyl-dl-leucine and N-acetyl-L-leucine. In contrast, the N-acetyl-D-leucine isomer had no effect at all on the behavioral recovery, and animals of this group showed the same recovery profile as those receiving a placebo. It is concluded that the N-acetyl-L-leucine isomer is the active part of the racemate component since it induces a significant acceleration of the vestibular compensation process similar (and even better) to that observed under treatment with the racemate component only. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Leucine zipper motif inspiration: a two-dimensional leucine Velcro-like array in peptide coordination polymers generates hydrophobicity.

    PubMed

    Rodríguez-Hermida, Sabina; Evangelio, Emi; Rubio-Martínez, Marta; Imaz, Inhar; Verdaguer, Albert; Juanhuix, Jordi; Maspoch, Daniel

    2017-08-29

    Here, we show that the well-known hydrophobic leucine (Leu) zipper motif (also known as the coiled-coil or Leu scissors motif), typically found in proteins, can be used as a source of inspiration in coordination polymers built from Leu-containing dipeptides or tripeptides. We demonstrate that this motif can be extended to form Velcro-like layers of Leu, and that the hydrophobicity of these layers is transferred to coordination polymers, thereby enabling the development of a new type of hydrophobic materials.

  1. Sestrin regulation of TORC1: Is Sestrin a leucine sensor?

    SciTech Connect

    Lee, J. H.; Cho, U. -S.; Karin, M.

    2016-06-07

    Sestrins are highly conserved, stress-inducible proteins that inhibit target of rapamycin complex 1 (TORC1) signaling. After their transcriptional induction, both vertebrate and invertebrate Sestrins turn on the adenosine monophosphate (AMP)–activated protein kinase (AMPK), which activates the tuberous sclerosis complex (TSC), a key inhibitor of TORC1 activation. However, Sestrin overexpression, on occasion, can result in TORC1 inhibition even in AMPK-deficient cells. This effect has been attributed to Sestrin’s ability to bind the TORC1-regulating GATOR2 protein complex, which was postulated to control trafficking of TORC1 to lysosomes. How the binding of Sestrins to GATOR2 is regulated and how it contributes to TORC1 inhibition are unknown. New findings suggest that the amino acid leucine specifically disrupts the association of Sestrin2 with GATOR2, thus explaining how leucine and related amino acids stimulate TORC1 activity. We discuss whether and how these findings fit what has already been learned about Sestrin-mediated TORC1 inhibition from genetic studies conducted in fruit flies and mammals.

  2. SdAb heterodimer formation using leucine zippers

    NASA Astrophysics Data System (ADS)

    Goldman, Ellen R.; Anderson, George P.; Brozozog-Lee, P. Audrey; Zabetakis, Dan

    2013-05-01

    Single domain antibodies (sdAb) are variable domains cloned from camel, llama, or shark heavy chain only antibodies, and are among the smallest known naturally derived antigen binding fragments. SdAb derived from immunized llamas are able to bind antigens with high affinity, and most are capable of refolding after heat or chemical denaturation to bind antigen again. We hypothesized that the ability to produce heterodimeric sdAb would enable reagents with the robust characteristics of component sdAb, but with dramatically improved overall affinity through increased avidity. Previously we had constructed multimeric sdAb by genetically linking sdAb that bind non-overlapping epitopes on the toxin, ricin. In this work we explored a more flexible approach; the construction of multivalent binding reagents using multimerization domains. We expressed anti-ricin sdAb that recognize different epitopes on the toxin as fusions with differently charged leucine zippers. When the initially produced homodimers are mixed the leucine zipper domains will pair to produce heterodimers. We used fluorescence resonance energy transfer to confirm heterodimer formation. Surface plasmon resonance, circular dichroism, enzyme linked immunosorbent assays, and fluid array assays were used to characterize the multimer constructs, and evaluate their utility in toxin detection.

  3. Prostate Cancer Cells in Different Androgen Receptor Status Employ Different Leucine Transporters.

    PubMed

    Otsuki, Hideo; Kimura, Toru; Yamaga, Takashi; Kosaka, Takeo; Suehiro, Jun-Ichi; Sakurai, Hiroyuki

    2017-02-01

    Leucine stimulates cancer cell proliferation through the mTOR pathway, therefore, inhibiting leucine transporters may be a novel therapeutic target for cancer. L-type amino acid transporter (LAT) 1, a Na(+) -independent amino acid transporter, is highly expressed in many tumor cells. However, leucine transporter(s) in different stages of prostate cancer, particularly in the stages of castration resistance with androgen receptor (AR) expression, is unclear. LNCaP and DU145 and PC-3 cell lines were used as a model of androgen dependent, and metastatic prostate cancer. A new "LN-cr" cell line was established after culturing LNCaP cells for 6 months under androgen-free conditions, which is considered a model of castration resistant prostate cancer (CRPC) with androgen AR expression. The expression of leucine transporters was investigated with quantitative PCR and immunofluorescence. Uptake of (14) C Leucine was examined in the presence or absence of BCH (a pan-LAT inhibitor), JPH203 (an LAT1-specific inhibitor), or Na(+) . Cell growth was assessed with MTT assay. siRNA studies were performed to evaluate the indispensability of y(+) LAT2 on leucine uptake and cell viability in LN-cr. Cell viability showed a 90% decrease in the absence of leucine in all four cell lines. LNCaP cells principally expressed LAT3, and their leucine uptake was more than 90% Na(+) -independent. BCH, but not JPH203, inhibited leucine uptake, and cell proliferation (IC50BCH :15 mM). DU145 and PC-3 cells predominantly expressed LAT1. Leucine uptake and cell growth were suppressed by BCH or JPH203 in a dose-dependent manner (IC50BCH : ∼20 mM, IC50JPH203 : ∼5 µM). In LN-cr cells, Na(+) -dependent uptake of leucine was 3.8 pmol/mgprotein/min, while, Na(+) -independent uptake was only 0.52 (P < 0.05). Leucine uptake of LN-cr was largely (∼85%) Na(+) -dependent. y(+) LAT2 expression was confirmed in LN-cr. Knockdown of y(+) LAT2 lead to significant leucine uptake inhibition (40%) and

  4. Dietary leucine requirement for juvenile large yellow croaker Pseudosciaena crocea (Richardson, 1846)

    NASA Astrophysics Data System (ADS)

    Li, Yan; Ai, Qinghui; Mai, Kangsen; Xu, Wei; Cheng, Zhenyan; He, Zhigang

    2010-12-01

    Dietary leucine requirement for juvenile large yellow croaker, Pseudosciaena crocea Richardson 1846 (initial body weight 6.0 g ± 0.1 g) was determined using dose-response method. Six isonitogenous (crude protein 43%) and isoenergetic (19 kJ g-1) practical diets containing six levels of leucine (Diets 1-6) ranging from 1.23% to 4.80% (dry matter) were made at about 0.7% increment of leucine. Equal amino acid nitrogen was maintained by replacing leucine with glutamic acid. Triplicate groups of 60 individuals were fed to apparent satiation by hand twice daily (05:00 and 17:30). The water temperature was 26-32°C, salinity 26-30 and dissolved oxygen approximately 7 mg L-1 during the experimental period. Final weight (FW) of large yellow croaker initially increased with increasing level of dietary leucine but then decreased at further higher level of leucine. The highest FW was obtained in fish fed diet with 3.30% Leucine (Diet 4). FW of fish fed the diet with 4.80% Leucine (Diet 6) was significantly lower than those fed Diet 4. However, no significant differences were observed between the other dietary treatments. Feed efficiency (FE) and whole body composition were independent of dietary leucine contents ( P > 0.05). The results indicated that leucine was essential for growth of juvenile large yellow croaker. On the basis of FW, the optimum dietary leucine requirement for juvenile large yellow croaker was estimated to be 2.92% of dry matter (6.79% of dietary protein).

  5. Does hypothalamic SIRT1 regulate aging?

    PubMed

    Ramadori, Giorgio; Coppari, Roberto

    2011-03-01

    In virtually all organisms, life expectancy is profoundly affected by caloric intake. For example, dietary restriction (DR; a feeding regimen of fewer calories compared to the ad libitum level without causing malnutrition) has been shown to lengthen, whereas hypercaloric (HC) diet feeding to shorten, lifespan. Recent findings in invertebrates indicate that specialized groups of cells (e.g.: metabolic-sensing neurons) detect changes in caloric intake and convey energy-status-variation signals to other cells in the body to regulate lifespan. In mammals, whether metabolic-sensing neurons govern aging in a cell-non-autonomous fashion is unknown. Yet, this is a captivating and testable hypothesis.

  6. Dynamic localization of glucokinase and its regulatory protein in hypothalamic tanycytes.

    PubMed

    Salgado, Magdiel; Tarifeño-Saldivia, Estefanía; Ordenes, Patricio; Millán, Carola; Yañez, María José; Llanos, Paula; Villagra, Marcos; Elizondo-Vega, Roberto; Martínez, Fernando; Nualart, Francisco; Uribe, Elena; de Los Angeles García-Robles, María

    2014-01-01

    Glucokinase (GK), the hexokinase involved in glucose sensing in pancreatic β cells, is also expressed in hypothalamic tanycytes, which cover the ventricular walls of the basal hypothalamus and are implicated in an indirect control of neuronal activity by glucose. Previously, we demonstrated that GK was preferentially localized in tanycyte nuclei in euglycemic rats, which has been reported in hepatocytes and is suggestive of the presence of the GK regulatory protein, GKRP. In the present study, GK intracellular localization in hypothalamic and hepatic tissues of the same rats under several glycemic conditions was compared using confocal microscopy and Western blot analysis. In the hypothalamus, increased GK nuclear localization was observed in hyperglycemic conditions; however, it was primarily localized in the cytoplasm in hepatic tissue under the same conditions. Both GK and GKRP were next cloned from primary cultures of tanycytes. Expression of GK by Escherichia coli revealed a functional cooperative protein with a S0.5 of 10 mM. GKRP, expressed in Saccharomyces cerevisiae, inhibited GK activity in vitro with a Ki 0.2 µM. We also demonstrated increased nuclear reactivity of both GK and GKRP in response to high glucose concentrations in tanycyte cultures. These data were confirmed using Western blot analysis of nuclear extracts. Results indicate that GK undergoes short-term regulation by nuclear compartmentalization. Thus, in tanycytes, GK can act as a molecular switch to arrest cellular responses to increased glucose.

  7. Dynamic Localization of Glucokinase and Its Regulatory Protein in Hypothalamic Tanycytes

    PubMed Central

    Ordenes, Patricio; Millán, Carola; Yañez, María José; Llanos, Paula; Villagra, Marcos; Elizondo-Vega, Roberto; Martínez, Fernando; Nualart, Francisco; Uribe, Elena; de los Angeles García-Robles, María

    2014-01-01

    Glucokinase (GK), the hexokinase involved in glucose sensing in pancreatic β cells, is also expressed in hypothalamic tanycytes, which cover the ventricular walls of the basal hypothalamus and are implicated in an indirect control of neuronal activity by glucose. Previously, we demonstrated that GK was preferentially localized in tanycyte nuclei in euglycemic rats, which has been reported in hepatocytes and is suggestive of the presence of the GK regulatory protein, GKRP. In the present study, GK intracellular localization in hypothalamic and hepatic tissues of the same rats under several glycemic conditions was compared using confocal microscopy and Western blot analysis. In the hypothalamus, increased GK nuclear localization was observed in hyperglycemic conditions; however, it was primarily localized in the cytoplasm in hepatic tissue under the same conditions. Both GK and GKRP were next cloned from primary cultures of tanycytes. Expression of GK by Escherichia coli revealed a functional cooperative protein with a S0.5 of 10 mM. GKRP, expressed in Saccharomyces cerevisiae, inhibited GK activity in vitro with a Ki 0.2 µM. We also demonstrated increased nuclear reactivity of both GK and GKRP in response to high glucose concentrations in tanycyte cultures. These data were confirmed using Western blot analysis of nuclear extracts. Results indicate that GK undergoes short-term regulation by nuclear compartmentalization. Thus, in tanycytes, GK can act as a molecular switch to arrest cellular responses to increased glucose. PMID:24739934

  8. Hypothalamic integration of body fluid regulation.

    PubMed Central

    Denton, D A; McKinley, M J; Weisinger, R S

    1996-01-01

    The progression of animal life from the paleozoic ocean to rivers and diverse econiches on the planet's surface, as well as the subsequent reinvasion of the ocean, involved many different stresses on ionic pattern, osmotic pressure, and volume of the extracellular fluid bathing body cells. The relatively constant ionic pattern of vertebrates reflects a genetic "set" of many regulatory mechanisms--particularly renal regulation. Renal regulation of ionic pattern when loss of fluid from the body is disproportionate relative to the extracellular fluid composition (e.g., gastric juice with vomiting and pancreatic secretion with diarrhea) makes manifest that a mechanism to produce a biologically relatively inactive extracellular anion HCO3- exists, whereas no comparable mechanism to produce a biologically inactive cation has evolved. Life in the ocean, which has three times the sodium concentration of extracellular fluid, involves quite different osmoregulatory stress to that in freshwater. Terrestrial life involves risk of desiccation and, in large areas of the planet, salt deficiency. Mechanisms integrated in the hypothalamus (the evolutionary ancient midbrain) control water retention and facilitate excretion of sodium, and also control the secretion of renin by the kidney. Over and above the multifactorial processes of excretion, hypothalamic sensors reacting to sodium concentration, as well as circumventricular organs sensors reacting to osmotic pressure and angiotensin II, subserve genesis of sodium hunger and thirst. These behaviors spectacularly augment the adaptive capacities of animals. Instinct (genotypic memory) and learning (phenotypic memory) are melded to give specific behavior apt to the metabolic status of the animal. The sensations, compelling emotions, and intentions generated by these vegetative systems focus the issue of the phylogenetic emergence of consciousness and whether primal awareness initially came from the interoreceptors and vegetative

  9. Dorsomedial hypothalamic NPY and energy balance control

    PubMed Central

    Bi, Sheng; Kim, Yonwook J.; Zheng, Fenping

    2012-01-01

    Neuropeptide Y (NPY) is a potent hypothalamic orexigenic peptide. Within the hypothalamus, Npy is primarily expressed in the arcuate nucleus (ARC) and the dorsomedial hypothalamus (DMH). While the actions of ARC NPY in energy balance control have been well studied, a role for DMH NPY is still being unraveled. In contrast to ARC NPY that serves as one of downstream mediators of actions of leptin in maintaining energy homeostasis, DMH NPY is not under the control of leptin. Npy gene expression in the DMH is regulated by brain cholecystokinin (CCK) and other yet to be identified molecules. The findings of DMH NPY overexpression or induction in animals with increased energy demands and in certain rodent models of obesity implicate a role for DMH NPY in maintaining energy homeostasis. In support of this view, adeno-associated virus (AAV)-mediated overexpression of NPY in the DMH causes increases in food intake and body weight and exacerbates high-fat diet-induced hyperphagia and obesity. Knockdown of NPY in the DMH via AAV-mediated RNAi ameliorates hyperphagia, obesity and glucose intolerance of Otsuka Long-Evans Tokushima Fatty rats in which DMH NPY overexpression has been proposed to play a causal role. NPY knockdown in the DMH also prevents high-fat diet-induced hyperphagia, obesity and impaired glucose homeostasis. A detailed examination of actions of DMH NPY reveals that DMH NPY specifically affects nocturnal meal size and produces an inhibitory action on within meal satiety signals. In addition, DMH NPY modulates energy expenditure likely through affecting brown adipocyte formation and thermogenic activity. Overall, the recent findings provide clear evidence demonstrating critical roles for DMH NPY in energy balance control, and also imply a potential role for DMH NPY in maintaining glucose homeostasis. PMID:23083763

  10. Hypothalamic regulation of sleep and arousal.

    PubMed

    McGinty, Dennis; Szymusiak, Ronald

    2003-09-01

    The hypnogenic function of the rostral hypothalamic region, particularly the preoptic area (POA) was established previously on the basis of lesion, neuronal unit recording, and neurochemical and thermal stimulation studies. Recent studies have mapped the locations of putative sleep-promoting neurons in the POA using c-Fos immunostaining techniques and confirmed these findings with electrophysiological methods. Segregated groups of sleep-active neurons have been localized in the ventrolateral POA (vlPOA) and median preoptic nucleus (MnPN). MnPN and vlPOA sleep-active neurons express the inhibitory transmitter, GABA. In vlPOA neurons, GABA is co-localized with a second inhibitory transmitter, galanin. Descending projections from these sites terminate in putative arousal-promoting cell groups, including histaminergic, serotonergic, orexinergic, noradrenergic, and cholinergic neurons. These findings suggest the hypothesis that non-REM sleep occurs as a consequence of GABAergic and galaninergic inhibition of arousal-promoting neurons resulting from activation of vlPOA and MnPN sleep-promoting neurons. In support of this hypothesis, it was shown that putative sleep-promoting and arousal-promoting neurons exhibit reciprocal changes in discharge across the sleep-wake cycle and that GABA release in wake-promoting sites increases during nonREM sleep. In addition, some POA sleep-active neurons are warm-sensitive. Local POA warming inhibits discharge of multiple arousal-promoting neuronal groups. POA warming, unit recording, and lesion studies also show that POA regulates the amount of delta EEG activity within nonREM sleep, and index of the depth of sleep. Finally, there is evidence that arousal systems inhibit vlPOA and MnPN neurons and the POA hypnogenic mechanism. Mutually-inhibitory interactions between sleep-promoting and arousal-promoting systems are hypothesized to form a functional sleep-wake switch.

  11. Dorsomedial hypothalamic NPY and energy balance control.

    PubMed

    Bi, Sheng; Kim, Yonwook J; Zheng, Fenping

    2012-12-01

    Neuropeptide Y (NPY) is a potent hypothalamic orexigenic peptide. Within the hypothalamus, Npy is primarily expressed in the arcuate nucleus (ARC) and the dorsomedial hypothalamus (DMH). While the actions of ARC NPY in energy balance control have been well studied, a role for DMH NPY is still being unraveled. In contrast to ARC NPY that serves as one of downstream mediators of actions of leptin in maintaining energy homeostasis, DMH NPY is not under the control of leptin. Npy gene expression in the DMH is regulated by brain cholecystokinin (CCK) and other yet to be identified molecules. The findings of DMH NPY overexpression or induction in animals with increased energy demands and in certain rodent models of obesity implicate a role for DMH NPY in maintaining energy homeostasis. In support of this view, adeno-associated virus (AAV)-mediated overexpression of NPY in the DMH causes increases in food intake and body weight and exacerbates high-fat diet-induced hyperphagia and obesity. Knockdown of NPY in the DMH via AAV-mediated RNAi ameliorates hyperphagia, obesity and glucose intolerance of Otsuka Long-Evans Tokushima Fatty rats in which DMH NPY overexpression has been proposed to play a causal role. NPY knockdown in the DMH also prevents high-fat diet-induced hyperphagia, obesity and impaired glucose homeostasis. A detailed examination of actions of DMH NPY reveals that DMH NPY specifically affects nocturnal meal size and produces an inhibitory action on within meal satiety signals. In addition, DMH NPY modulates energy expenditure likely through affecting brown adipocyte formation and thermogenic activity. Overall, the recent findings provide clear evidence demonstrating critical roles for DMH NPY in energy balance control, and also imply a potential role for DMH NPY in maintaining glucose homeostasis. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Effect of insulin and plasma amino acid concentrations on leucine metabolism in man. Role of substrate availability on estimates of whole body protein synthesis.

    PubMed Central

    Castellino, P; Luzi, L; Simonson, D C; Haymond, M; DeFronzo, R A

    1987-01-01

    We examined the effect of insulin and plasma amino acid concentrations on leucine kinetics in 15 healthy volunteers (age 22 +/- 2 yr) using the euglycemic insulin clamp technique and an infusion of [1-14C]leucine. Four different experimental conditions were examined: (a) study one, high insulin with reduced plasma amino acid concentrations; (b) study two, high insulin with maintenance of basal plasma amino acid concentrations; (c) study three, high insulin with elevated plasma amino acid concentrations; and (d) study four, basal insulin with elevated plasma amino acid concentrations. Data were analyzed using both the plasma leucine and alpha-ketoisocaproate (the alpha-ketoacid of leucine) specific activities. In study one total leucine flux, leucine oxidation, and nonoxidative leucine disposal (an index of whole body protein synthesis) all decreased (P less than 0.01) regardless of the isotope model utilized. In study two leucine flux did not change, while leucine oxidation increased (P less than 0.01) and nonoxidative leucine disposal was maintained at the basal rate; endogenous leucine flux (an index of whole body protein degradation) decreased (P less than 0.01). In study three total leucine flux, leucine oxidation, and nonoxidative leucine disposal all increased significantly (P less than 0.01). In study four total leucine flux, leucine oxidation, and nonoxidative leucine disposal all increased (P less than 0.001), while endogenous leucine flux decreased (P less than 0.001). We conclude that: (a) hyperinsulinemia alone decreases plasma leucine concentration and inhibits endogenous leucine flux (protein breakdown), leucine oxidation, and nonoxidative leucine disposal (protein synthesis); (b) hyperaminoacidemia, whether in combination with hyperinsulinemia or with maintained basal insulin levels decreases endogenous leucine flux and stimulates both leucine oxidation and nonoxidative leucine disposal. PMID:3316280

  13. Metabolic Context Regulates Distinct Hypothalamic Transcriptional Responses to Antiaging Interventions

    PubMed Central

    Stranahan, Alexis M.; Martin, Bronwen; Chadwick, Wayne; Park, Sung-Soo; Wang, Liyun; Becker, Kevin G.; WoodIII, William H.; Zhang, Yongqing; Maudsley, Stuart

    2012-01-01

    The hypothalamus is an essential relay in the neural circuitry underlying energy metabolism that needs to continually adapt to changes in the energetic environment. The neuroendocrine control of food intake and energy expenditure is associated with, and likely dependent upon, hypothalamic plasticity. Severe disturbances in energy metabolism, such as those that occur in obesity, are therefore likely to be associated with disruption of hypothalamic transcriptomic plasticity. In this paper, we investigated the effects of two well-characterized antiaging interventions, caloric restriction and voluntary wheel running, in two distinct physiological paradigms, that is, diabetic (db/db) and nondiabetic wild-type (C57/Bl/6) animals to investigate the contextual sensitivity of hypothalamic transcriptomic responses. We found that, both quantitatively and qualitatively, caloric restriction and physical exercise were associated with distinct transcriptional signatures that differed significantly between diabetic and non-diabetic mice. This suggests that challenges to metabolic homeostasis regulate distinct hypothalamic gene sets in diabetic and non-diabetic animals. A greater understanding of how genetic background contributes to hypothalamic response mechanisms could pave the way for the development of more nuanced therapeutics for the treatment of metabolic disorders that occur in diverse physiological backgrounds. PMID:22934110

  14. Behavioural responses to hypothalamic cooling and heating in the rat.

    PubMed

    Cabanac, M; Dib, B

    1983-03-28

    Rats with hypothalamic thermodes had their hypothalamus cooled or warmed for short sessions. In a first series of experiments, rats could bar-press to obtain fanning with cool air. Cooling the hypothalamus did not suppress or inhibit this behaviour although rectal temperature was markedly increased. In a second series of experiments, bar-pressing would warm the water flowing in the thermode. The rats thus self suppressed the cooling of their hypothalamus. This behaviour was absent at 10 degrees C ambient temperature, and increased with increasing ambient temperature up to 35 degrees C. The result of this behaviour was a small hyperthermia in warm and hot environment compared to control when the rats could not self-suppress the cooling of hypothalamus. The results of both experiments suggest that no conscious direct sensation is aroused by hypothalamic cooling. Hypothalamic heating increased the rat's bar-pressing for cool air and decreased the rat's rectal temperature. When pressure on the lever would suppress a warm hypothalamic stimulus rats self-cooled their hypothalamus, especially in warm environments. Such behaviour resulted in an increased somatic hyperthermia due to the warm environment and hypothalamic cooling. These results are compatible with the hypothesis of a direct conscious sensation from a warm hypothalamus.

  15. Leucine Modulates Mitochondrial Biogenesis and SIRT1-AMPK Signaling in C2C12 Myotubes

    PubMed Central

    Liang, Chunzi; Curry, Benjamin J.; Brown, Patricia L.; Zemel, Michael B.

    2014-01-01

    Previous studies from this laboratory demonstrate that dietary leucine protects against high fat diet-induced mitochondrial impairments and stimulates mitochondrial biogenesis and energy partitioning from adipocytes to muscle cells through SIRT1-mediated mechanisms. Moreover, β-hydroxy-β-methyl butyrate (HMB), a metabolite of leucine, has been reported to activate AMPK synergistically with resveratrol in C2C12 myotubes. Therefore, we hypothesize that leucine-induced activation of SIRT1 and AMPK is the central event that links the upregulated mitochondrial biogenesis and fatty acid oxidation in skeletal muscle. Thus, C2C12 myotubes were treated with leucine (0.5 mM), alanine (0.5 mM), valine (0.5 mM), EX527 (SIRT1 inhibitor, 25 μM), and Compound C (AMPK inhibitor, 25 μM) alone or in combination to determine the roles of AMPK and SIRT1 in leucine-modulation of energy metabolism. Leucine significantly increased mitochondrial content, mitochondrial biogenesis-related genes expression, fatty acid oxidation, SIRT1 activity and gene expression, and AMPK phosphorylation in C2C12 myotubes compared to the controls, while EX527 and Compound C markedly attenuated these effects. Furthermore, leucine treatment for 24 hours resulted in time-dependent increases in cellular NAD+, SIRT1 activity, and p-AMPK level, with SIRT1 activation preceding that of AMPK, indicating that leucine activation of SIRT1, rather than AMPK, is the primary event. PMID:25400942

  16. The intra-hippocampal leucine administration impairs memory consolidation and LTP generation in rats.

    PubMed

    Glaser, Viviane; Carlini, Valeria P; Gabach, Laura; Ghersi, Marisa; de Barioglio, Susana Rubiales; Ramirez, Oscar A; Perez, Mariela F; Latini, Alexandra

    2010-10-01

    Leucine accumulates in fluids and tissues of patients affected by maple syrup urine disease, an inherited metabolic disorder, predominantly characterized by neurological dysfunction. Although, a variable degree of cognition/psychomotor delay/mental retardation is found in a considerable number of individuals affected by this deficiency, the mechanisms underlying the neuropathology of these alterations are still not defined. Therefore, the aim of this study was to investigate the effect of acute intra-hippocampal leucine administration in the step-down test in rats. In addition, the leucine effects on the electrophysiological parameter, long-term potentiation generation, and on the activities of the respiratory chain were also investigated. Male Wistar rats were bilaterally administrated with leucine (80 nmol/hippocampus; 160 nmol/rat) or artificial cerebrospinal fluid (controls) into the hippocampus immediately post-training in the behavioral task. Twenty-four hours after training in the step-down test, the latency time was evaluated and afterwards animals were sacrificed for assessing the ex vivo biochemical measurements. Leucine-treated animals showed impairment in memory consolidation and a complete inhibition of long-term potentiation generation at supramaximal stimulation. In addition, a significant increment in complex IV activity was observed in hippocampus from leucine-administered rats. These data strongly indicate that leucine compromise memory consolidation, and that impairment of long-term potentiation generation and unbalance of the respiratory chain may be plausible mechanisms underlying the deleterious leucine effect on cognition.

  17. Kinetic Behavior of Leucine and Other Amino Acids Modulating Cognitive Performance via mTOR Pathway

    DTIC Science & Technology

    2011-12-02

    Acid BBB Transporter Type Structure Leucine L1 Essential Neutral Non-polar (hydrophobic) Branched chain Aspartic Acid Acidic X- Acidic Polar Glutamine...compared with other tissues. • Effects of leucine on other amino acids were analyzed. Those measured were aspartic acid , glutamic acid, serine, histidine

  18. Complete genome sequence of Corynebacterium glutamicum CP, a Chinese l-leucine producing strain.

    PubMed

    Gui, Yongli; Ma, Yuechao; Xu, Qingyang; Zhang, Chenglin; Xie, Xixian; Chen, Ning

    2016-02-20

    Here, we report the complete genome sequence of Corynebacterium glutamicum CP, an industrial l-leucine producing strain in China. The whole genome consists of a circular chromosome and a plasmid. The comparative genomics analysis shows that there are many mutations in the key enzyme coding genes relevant to l-leucine biosynthesis compared to C. glutamicum ATCC 13032.

  19. Stimulation of muscle protein synthesis by leucine is dependent on plasma amino acid availability

    USDA-ARS?s Scientific Manuscript database

    We have reported that a physiological increase in plasma leucine increased translation initiation factor activity during 60- and 120-min leucine infusion. Muscle protein synthesis was stimulated at 60 min but not at 120 min, perhaps due to the decrease (-50%) in plasma essential amino acids (AA). ...

  20. Genetically encoded FRET-based nanosensor for in vivo measurement of leucine.

    PubMed

    Mohsin, Mohd; Abdin, M Z; Nischal, Lata; Kardam, Hemant; Ahmad, Altaf

    2013-12-15

    Besides fundamental role in protein synthesis, leucine has metabolic roles as energy substrates, precursors for synthesis of other amino acids and as a modulator of muscle protein synthesis via the insulin-signaling pathway. Leucine concentration in cell and tissue is temporally dynamic as the metabolism of leucine is regulated through multiple enzymes and transporters. Assessment of cell-type specific activities of transporters and enzymes by physical fractionation is extremely challenging. Therefore, a method of reporting leucine dynamics at the cellular level is highly desirable. Given this, we developed a series of genetically encoded nanosensors for real-time in vivo measurement of leucine at cellular level. A leucine binding periplasmic binding protein (LivK) of Escherichia coli K12 was flanked with CFP (cyan fluorescent protein) and YFP (yellow fluorescent protein) at N-terminus and C-terminus, respectively. The constructed nanosensors allowed in vitro determination of fluorescence resonance energy transfer (FRET) changes in a concentration-dependent manner. These sensors were found to be specific to leucine, and stable to pH-changes within a physiological range. Genetically encoded sensors can be targeted to a specific cell type, and allow dynamic measurement of leucine concentration in bacterial and yeast cells.

  1. Prolonged stimulation of protein synthesis by leucine is dependent on amino acid availability

    USDA-ARS?s Scientific Manuscript database

    Leucine is unique among the amino acids in its ability to enhance protein synthesis by activating translation initiation (Kimball and Jefferson, 2005). Our laboratory has shown that raising leucine to postprandial levels, whilst keeping all other amino acids at the post absorptive, level acutely st...

  2. Triennial growth symposium: Leucine acts as a nutrient signal to stimulate protein synthesis in neonatal pigs

    USDA-ARS?s Scientific Manuscript database

    The postprandial increases in AA and insulin independently stimulate protein synthesis in skeletal muscle of piglets. Leucine is an important mediator of the response to AA. We have shown that the postprandial increase in leucine, but not isoleucine or valine, acutely stimulates muscle protein synth...

  3. Differential effects of long-term leucine infusion on tissue protein synthesis in neonatal pigs

    USDA-ARS?s Scientific Manuscript database

    Leucine is unique among the amino acids in its ability to promote protein synthesis by activating translation initiation via the mammalian target of rapamycin (mTOR) pathway. Previously, we showed that leucine infusion acutely stimulates protein synthesis in fast-twitch glycolytic muscle of neonatal...

  4. Long-term leucine induced stimulation of muscle protein synthesis is amino acid dependent

    USDA-ARS?s Scientific Manuscript database

    Infusing leucine for 1 h increases skeletal muscle protein synthesis in the neonate, but this is not sustained for 2 h unless the corresponding fall in amino acids is prevented. This study aimed to determine whether a continuous leucine infusion can stimulate protein synthesis for a prolonged period...

  5. Risk factors for mortality caused by hypothalamic obesity in children with hypothalamic tumours.

    PubMed

    Haliloglu, B; Atay, Z; Guran, T; Abalı, S; Bas, S; Turan, S; Bereket, A

    2016-10-01

    Hypothalamic obesity (HyOb) is a common complication of childhood hypothalamic tumours. Patients with HyOb probably have a higher mortality rate than those with other types of obesity due in many cases to obstructive sleep apnoea/hypoventilation. To identify predictive factors for mortality caused by HyOb in children. Twenty children with HyOb secondary to hypothalamic tumours that were followed-up for ≥3 years and aged <15 years at diagnosis, and received supraphysiological glucocorticoid treatment for ≤1 month. Mean age at diagnosis was 6.36 ± 3.60 years. Mean body mass index (BMI) Standard deviation of the samples (SDS) increased from 0.77 ± 1.26 to 2.66 ± 1.45 during the first 6 months, but slowed from month 6-12 (2.73 ± 1.35). ΔBMI SDS at 0-6 months was significantly higher in patients aged <6 years at diagnosis than in those aged >6 years at diagnosis (3.71 ± 1.96 vs. 0.83 ± 0.73, P < 0.001). Maximum BMI SDS was also significantly higher in the younger group (3.88 ± 1.39 vs. 2.79 ± 0.64, P < 0.05). In all, four patients died and the mortality rate was significantly higher in the patients with a further increase in BMI SDS > 1 SDS after 6 months of therapy (RR: 8.4, P < 0.05). Both overall mortality and obesity-related mortality rates were higher in the patients aged <6 years at diagnosis (4.5-fold, 7.2-fold higher, respectively, P > 0.05). The mortality rate was also 3.7-fold higher in the patients with a maximum BMI SDS ≥ 3 at any time during the first 3 years after therapy(P > 0.05). An increase in BMI SDS after 6 months of therapy was observed to be a risk factor for mortality caused by HyOb. In addition, age <6 years at diagnosis and a maximum BMI SDS ≥ 3 were associated with a higher mortality rate, indicating that earlier and more aggressive treatment of obesity is required. © 2015 World Obesity.

  6. Thermodynamic analysis of the heterodimerization of leucine zippers of Jun and Fos transcription factors

    SciTech Connect

    Seldeen, Kenneth L.; McDonald, Caleb B.; Deegan, Brian J.

    2008-10-31

    Jun and Fos are components of the AP1 family of transcription factors and bind to the promoters of a diverse multitude of genes involved in critical cellular responses such as cell growth and proliferation, cell cycle regulation, embryonic development and cancer. Here, using the powerful technique of isothermal titration calorimetry, we characterize the thermodynamics of heterodimerization of leucine zippers of Jun and Fos. Our data suggest that the heterodimerization of leucine zippers is driven by enthalpic forces with unfavorable entropy change at physiological temperatures. Furthermore, the basic regions appear to modulate the heterodimerization of leucine zippers and may undergo at least partial folding upon heterodimerization. Large negative heat capacity changes accompanying the heterodimerization of leucine zippers are consistent with the view that leucine zippers do not retain {alpha}-helical conformations in isolation and that the formation of the native coiled-coil {alpha}-helical dimer is attained through a coupled folding-dimerization mechanism.

  7. Dietary L-leucine improves the anemia in a mouse model for Diamond-Blackfan anemia.

    PubMed

    Jaako, Pekka; Debnath, Shubhranshu; Olsson, Karin; Bryder, David; Flygare, Johan; Karlsson, Stefan

    2012-09-13

    Diamond-Blackfan anemia (DBA) is a congenital erythroid hypoplasia caused by a functional haploinsufficiency of genes encoding for ribosomal proteins. Recently, a case study reported a patient who became transfusion-independent in response to treatment with the amino acid L-leucine. Therefore, we have validated the therapeutic effect of L-leucine using our recently generated mouse model for RPS19-deficient DBA. Administration of L-leucine significantly improved the anemia in Rps19-deficient mice (19% improvement in hemoglobin concentration; 18% increase in the number of erythrocytes), increased the bone marrow cellularity, and alleviated stress hematopoiesis. Furthermore, the therapeutic response to L-leucine appeared specific for Rps19-deficient hematopoiesis and was associated with down-regulation of p53 activity. Our study supports the rationale for clinical trials of L-leucine as a therapeutic agent for DBA.

  8. Hypothalamic BOLD response to glucose intake and hypothalamic volume are similar in anorexia nervosa and healthy control subjects

    PubMed Central

    van Opstal, Anna M.; Westerink, Anna M.; Teeuwisse, Wouter M.; van der Geest, Mirjam A. M.; van Furth, Eric F.; van der Grond, Jeroen

    2015-01-01

    Background: Inconsistent findings about the neurobiology of Anorexia Nervosa (AN) hinder the development of effective treatments for this severe mental disorder. Therefore, the need arises for elucidation of neurobiological factors involved in the pathophysiology of AN. The hypothalamus plays a key role in the neurobiological processes that govern food intake and energy homeostasis, processes that are disturbed in anorexia nervosa (AN). The present study will assess the hypothalamic response to energy intake and the hypothalamic structure in patients with AN and healthy controls. Methods: Ten women aged 18–30 years diagnosed with AN and 11 healthy, lean (BMI < 23 kg/m2) women in the same age range were recruited. We used functional magnetic resonance imaging (MRI) to determine function of the hypothalamus in response to glucose. Structural MRI was used to determine differences in hypothalamic volume and local gray matter volume using manual segmentation and voxel-based morphometry. Results: No differences were found in hypothalamic volume and neuronal activity in response to a glucose load between the patients and controls. Whole brain structural analysis showed a significant decrease in gray matter volume in the cingulate cortex in the AN patients, bilaterally. Conclusions: We argue that in spite of various known changes in the hypothalamus the direct hypothalamic response to glucose intake is similar in AN patients and healthy controls. PMID:25999808

  9. Hypothalamic Obesity in Craniopharyngioma Patients: Disturbed Energy Homeostasis Related to Extent of Hypothalamic Damage and Its Implication for Obesity Intervention

    PubMed Central

    Roth, Christian L.

    2015-01-01

    Hypothalamic obesity (HO) occurs in patients with tumors and lesions in the medial hypothalamic region. Hypothalamic dysfunction can lead to hyperinsulinemia and leptin resistance. This review is focused on HO caused by craniopharyngiomas (CP), which are the most common childhood brain tumors of nonglial origin. Despite excellent overall survival rates, CP patients have substantially reduced quality of life because of significant long-term sequelae, notably severe obesity in about 50% of patients, leading to a high rate of cardiovascular mortality. Recent studies reported that both hyperphagia and decreased energy expenditure can contribute to severe obesity in HO patients. Recognized risk factors for severe obesity include large hypothalamic tumors or lesions affecting several medial and posterior hypothalamic nuclei that impact satiety signaling pathways. Structural damage in these nuclei often lead to hyperphagia, rapid weight gain, central insulin and leptin resistance, decreased sympathetic activity, low energy expenditure, and increased energy storage in adipose tissue. To date, most efforts to treat HO have shown disappointing long-term success rates. However, treatments based on the distinct pathophysiology of disturbed energy homeostasis related to CP may offer options for successful interventions in the future. PMID:26371051

  10. Gelastic epilepsy without hypothalamic hamartoma: three additional cases.

    PubMed

    Savasta, Salvatore; Budetta, Mauro; Spartà, Maria Valentina; Carpentieri, Maria Luisa; Trasimeni, Guido; Zavras, Niki; Villa, Maria Pia; Parisi, Pasquale

    2014-08-01

    We describe three children with gelastic seizures without hypothalamic hamartoma whose seizures were characterized by typical laughing attacks associated or not with other seizure types. Ictal/interictal EEG and magnetic resonance imaging were performed. All three subjects showed a good response to carbamazepine therapy with complete seizure control in addition to a benign clinical and cognitive outcome. These three cases confirm that gelastic epilepsy without hypothalamic hamartoma, both in cryptogenic or symptomatic patients (one child showed a dysplastic right parietotemporal lesion), usually has a more benign natural history, and carbamazepine seems to be the most efficacious therapy to obtain both immediate and long-term seizure control. These findings need to be confirmed in a larger sample of children affected by gelastic epilepsy without hypothalamic hamartoma.

  11. The Role of Hypothalamic Neuropeptides in Neurogenesis and Neuritogenesis

    PubMed Central

    Bakos, Jan; Zatkova, Martina; Bacova, Zuzana; Ostatnikova, Daniela

    2016-01-01

    The hypothalamus is a source of neural progenitor cells which give rise to different populations of specialized and differentiated cells during brain development. Newly formed neurons in the hypothalamus can synthesize and release various neuropeptides. Although term neuropeptide recently undergoes redefinition, small-size hypothalamic neuropeptides remain major signaling molecules mediating short- and long-term effects on brain development. They represent important factors in neurite growth and formation of neural circuits. There is evidence suggesting that the newly generated hypothalamic neurons may be involved in regulation of metabolism, energy balance, body weight, and social behavior as well. Here we review recent data on the role of hypothalamic neuropeptides in adult neurogenesis and neuritogenesis with special emphasis on the development of food intake and social behavior related brain circuits. PMID:26881105

  12. Hypothalamic AMPK as a Regulator of Energy Homeostasis

    PubMed Central

    Huynh, My Khanh Q.; Kinyua, Ann W.; Yang, Dong Joo

    2016-01-01

    Activated in energy depletion conditions, AMP-activated protein kinase (AMPK) acts as a cellular energy sensor and regulator in both central nervous system and peripheral organs. Hypothalamic AMPK restores energy balance by promoting feeding behavior to increase energy intake, increasing glucose production, and reducing thermogenesis to decrease energy output. Besides energy state, many hormones have been shown to act in concert with AMPK to mediate their anorexigenic and orexigenic central effects as well as thermogenic influences. Here we explore the factors that affect hypothalamic AMPK activity and give the underlying mechanisms for the role of central AMPK in energy homeostasis together with the physiological effects of hypothalamic AMPK on energy balance restoration. PMID:27547453

  13. Hypothalamic adipic hypernatraemia syndrome with normal osmoregulation of vasopressin.

    PubMed

    López-Capapé, Marta; Golmayo, Luz; Lorenzo, Gustavo; Gallego, Nieves; Barrio, Raquel

    2004-10-01

    Adipsic hypernatraemia is an uncommon disorder in childhood caused by a defect in the osmoregulation of thirst, leading to impairment of water homeostasis and chronic hyperosmolality of body fluids. Adipsia is often associated with an abnormality in osmoregulated vasopressin secretion due to the close proximity of the hypothalamic osmoreceptors that control thirst with those regulating vasopressin secretion. Hypothalamic lesions of diverse aetiology (vascular abnormalities, neoplasms, granulomatous diseases, trauma etc.) have been described in this syndrome. We report a 12-year-old boy with evident weight loss due to hypernatraemic dehydration with a selective defect in osmoregulation of thirst and normal vasopressin secretion with no demonstrable structural lesion. To date, only six paediatric patients with this condition have been described in the literature. Hypothalamic adipsic hypernatraemia syndrome must be suspected when a dehydrated patient denies thirst. The study of antidiuretic function is necessary because the osmoregulation of vasopressin secretion could be altered.

  14. Hypothalamic Lipids: Key Regulators of Whole Body Energy Balance.

    PubMed

    González-García, Ismael; Fernø, Johan; Diéguez, Carlos; Nogueiras, Rubén; López, Miguel

    2017-01-01

    Hypothalamic lipid metabolism plays a major role in the physiological regulation of energy balance. Modulation of several enzymatic activities that control lipid biosynthesis, such as fatty acid synthase and AMP-activated protein kinase, impacts both feeding and energy expenditure. However, lipids can also cause pathological alterations in the hypothalamus. Lipotoxicity is promoted by excess lipids in tissues not suitable for their storage. A large amount of evidence has demonstrated that lipotoxicity is a pathophysiological mechanism leading to metabolic diseases such as insulin resistance, cardiomyopathy, atherosclerosis, and steatohepatitis. Current data have reported that, similar to what is observed in peripheral tissues, complex lipids such as ceramides and sphingolipids act as lipotoxic species at the hypothalamic level to impact metabolism. Here, we will review what is currently known about hypothalamic lipid metabolism and the modulation of energy homeostasis. © 2016 S. Karger AG, Basel.

  15. A leucine zipper motif essential for gating of hyperpolarization-activated channels.

    PubMed

    Wemhöner, Konstantin; Silbernagel, Nicole; Marzian, Stefanie; Netter, Michael F; Rinné, Susanne; Stansfeld, Phillip J; Decher, Niels

    2012-11-23

    It is poorly understood how hyperpolarization-activated cyclic nucleotide-gated channels (HCNs) function. We have identified a leucine zipper in the S5 segment of HCNs, regulating hyperpolarization-activated and instantaneous current components. The leucine zipper is essential for HCN channel gating. The identification and functional characterization of the leucine zipper is an important step toward the understanding of HCN channel function. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are pacemakers in cardiac myocytes and neurons. Although their membrane topology closely resembles that of voltage-gated K(+) channels, the mechanism of their unique gating behavior in response to hyperpolarization is still poorly understood. We have identified a highly conserved leucine zipper motif in the S5 segment of HCN family members. In order to study the role of this motif for channel function, the leucine residues of the zipper were individually mutated to alanine, arginine, or glutamine residues. Leucine zipper mutants traffic to the plasma membrane, but the channels lose their sensitivity to open upon hyperpolarization. Thus, our data indicate that the leucine zipper is an important molecular determinant for hyperpolarization-activated channel gating. Residues of the leucine zipper interact with the adjacent S6 segment of the channel. This interaction is essential for voltage-dependent gating of the channel. The lower part of the leucine zipper, at the intracellular mouth of the channel, is important for stabilizing the closed state. Mutations at these sites increase current amplitudes or result in channels with deficient closing and increased min-P(o). Our data are further supported by homology models of the open and closed state of the HCN2 channel pore. Thus, we conclude that the leucine zipper of HCN channels is a major determinant for hyperpolarization-activated channel gating.

  16. Leucine supplementation via drinking water reduces atherosclerotic lesions in apoE null mice

    PubMed Central

    Zhao, Yang; Dai, Xiao-yan; Zhou, Zhou; Zhao, Ge-xin; Wang, Xian; Xu, Ming-jiang

    2016-01-01

    Aim: Recent evidence suggests that the essential amino acid leucine may be involved in systemic cholesterol metabolism. In this study, we investigated the effects of leucine supplementation on the development of atherosclerosis in apoE null mice. Methods: ApoE null mice were fed with chow supplemented with leucine (1.5% w/v) in drinking water for 8 week. Aortic atherosclerotic lesions were examined using Oil Red O staining. Plasma lipoprotein-cholesterol levels were measured with fast protein liquid chromatography. Hepatic gene expression was detected using real-time PCR and Western blot analyses. Results: Leucine supplementation resulted in 57.6% reduction of aortic atherosclerotic lesion area in apoE null mice, accompanied by 41.2% decrease of serum LDL-C levels and 40.2% increase of serum HDL-C levels. The body weight, food intake and blood glucose level were not affected by leucine supplementation. Furthermore, leucine supplementation increased the expression of Abcg5 and Abcg8 (that were involved in hepatic cholesterol efflux) by 1.28- and 0.86-fold, respectively, and significantly increased their protein levels. Leucine supplementation also increased the expression of Srebf1, Scd1 and Pgc1b (that were involved in hepatic triglyceride metabolism) by 3.73-, 1.35- and 1.71-fold, respectively. Consequently, leucine supplementation resulted in 51.77% reduction of liver cholesterol content and 2.2-fold increase of liver triglyceride content. Additionally, leucine supplementation did not affect the serum levels of IL-6, IFN-γ, TNF-α, IL-10 and IL-12, but markedly decreased the serum level of MCP-1. Conclusion: Leucine supplementation effectively attenuates atherosclerosis in apoE null mice by improving the plasma lipid profile and reducing systemic inflammation. PMID:26687933

  17. Differential effects of long-term leucine infusion on tissue protein synthesis in neonatal pigs

    PubMed Central

    Wilson, Fiona A.; Suryawan, Agus; Orellana, Renán A.; Gazzaneo, María C.; Nguyen, Hanh V.; Davis, Teresa A.

    2011-01-01

    Leucine is unique among the amino acids in its ability to promote protein synthesis by activating translation initiation via the mammalian target of rapamycin (mTOR) pathway. Previously, we showed that leucine infusion acutely stimulates protein synthesis in fast-twitch glycolytic muscle of neonatal pigs but this response cannot be maintained unless the leucine-induced fall in amino acids is prevented. To determine whether leucine can stimulate protein synthesis in muscles of different fiber types and in visceral tissues of the neonate in the long-term if baseline amino acid concentrations are maintained, overnight fasted neonatal pigs were infused for 24 h with saline, leucine (400 μmol kg−1 h−1), or leucine with replacement amino acids to prevent the leucine-induced hypoaminoacidemia. Changes in the fractional rate of protein synthesis and activation of mTOR, as determined by eukaryotic initiation factor 4E binding protein (4E-BP1) and S6 kinase 1 (S6K1) phosphorylation, in the gastrocnemius and masseter muscles, heart, liver, jejunum, kidney, and pancreas were measured. Leucine increased mTOR activation in the gastrocnemius and masseter muscles, liver, and pancreas, in both the absence and presence of amino acid replacement. However, protein synthesis in these tissues was increased only when amino acids were infused to maintain baseline levels. There were no changes in mTOR signaling or protein synthesis in the other tissues we examined. Thus, long-term infusion of leucine stimulates mTOR signaling in skeletal muscle and some visceral tissues but the leucine-induced stimulation of protein synthesis in these tissues requires sustained amino acid availability. PMID:20505962

  18. Effect of leucine uptake on hepatic and skeletal muscle gene expression in rats: a microarray analysis

    PubMed Central

    Cheon, Wookwang

    2015-01-01

    [Purpose] This study was performed to explore the physiological functions of leucine by exploring genes with leucine-dependent variability using DNA microarray. [Methods] Sprague-Dawley rats (n = 20) were separated into a HPD (30% High Protein Diet, n = 10) group and a NPD (0% Non Protein Diet, n = 10) group and fed a protein diet for 2 weeks. At the end of the 2-week period, the rats were fasted for 12-16 hours, further separated into subgroups within the HPD (Saline, n = 5, Leucine, n = 5) and NPD (Saline, n = 5, Leucine, n = 5) groups and administered with a leucine solution. The liver and muscles were harvested after 2 hours for RNA extraction. RNA purification from the isolated muscles and target gene identification using DNA chip were performed. The target gene was determined based on the results of the DNA chip experiment, and mRNA expression of the target gene was analyzed using Real-Time PCR. [Results] In the skeletal muscle, 27 genes were upregulated while 52 genes were down regulated after leucine administration in the NPD group. In the liver, 160 genes were up-regulated while 126 were down-regulated. The per2 gene was one of the genes with leucine-dependent induction in muscles and liver. [Conclusion] This study was performed to explore the physiological functions of leucine, however, a large number of genes showed variability. Therefore, it was difficult to definitively identify the genes linked with a particular physiological function. Various nutritional effects of leucine were observed. High variability in cytokines, receptors, and various membrane proteins were observed, which suggests that leucine functions as more than a nutrient. The interpretation may depend on investigators’ perspectives, therefore, discussion with relevant experts and the BCAA (Branched-Chain Amino Acids) society may be needed for effective utilization of this data. PMID:26244133

  19. Leucine improves protein nutritional status and regulates hepatic lipid metabolism in calorie-restricted rats.

    PubMed

    Pedroso, João Alfredo B; Nishimura, Luciana Sigueta; de Matos-Neto, Emídio Marques; Donato, Jose; Tirapegui, Julio

    2014-06-01

    Several studies have highlighted the potential of leucine supplementation for the treatment of metabolic diseases including type 2 diabetes and obesity. Caloric restriction is a common approach to improve the health in diabetic and obese subjects. However, very few studies assessed the effects of leucine supplementation in calorie-restricted animals. Rats were subjected to a 30% calorie-restricted diet for 6 weeks to study the effects of leucine supplementation on protein status markers and lipid metabolism. Caloric restriction reduced the body weight. However, increased leucine intake preserved body lean mass and protein mass and improved protein anabolism as indicated by the increased circulating levels of albumin and insulin-like growth factor-1 (IGF-1), and the liver expression of albumin and IGF-1 messenger RNA. Leucine supplementation also increased the circulating levels of interleukin-6 and leptin but did not affect the tumour necrosis factor-α and monocyte chemotactic protein-1 concentrations. Ketone bodies were increased in rats consuming a leucine-rich diet, but we observed no changes in cholesterol or triglycerides concentrations. Caloric restriction reduced the liver expression of peroxisome proliferator activated receptor-α and glucose-6-phosphatase, whereas leucine supplementation increased the liver expression of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA) reductase and sterol regulatory element-binding transcription factor 1. A leucine-rich diet during caloric restriction preserved whole body protein mass and improved markers of protein anabolism. In addition, leucine modulated the hepatic lipid metabolism. These results indicate that increased leucine intake may be useful in preventing excessive protein waste in conditions of large weight loss.

  20. Glutamate formation via the leucine-to-glutamate pathway of rat pancreas.

    PubMed

    Schachter, David; Buteau, Jean

    2014-06-01

    The leucine-to-glutamate (Leu→Glu) pathway, which metabolizes the carbon atoms of l-leucine to form l-glutamate, was studied by incubation of rat tissue segments with l-[U-(14)C]leucine and estimation of the [(14)C]glutamate formed. Metabolism of the leucine carbon chain occurs in most rat tissues, but maximal activity of the Leu→Glu pathway for glutamate formation is limited to the thoracic aorta and pancreas. In rat aorta, the Leu→Glu pathway functions to relax the underlying smooth muscle; its functions in the pancreas are unknown. This report characterizes the Leu→Glu pathway of rat pancreas and develops methods to examine its functions. Pancreatic segments effect net formation of glutamate on incubation with l-leucine, l-glutamine, or a mix of 18 other plasma amino acids at their concentrations in normal rat plasma. Glutamate formed from leucine remains mainly in the tissue, whereas that from glutamine enters the medium. The pancreatic Leu→Glu pathway uses the leucine carbons for net glutamate formation; the α-amino group is not used; the stoichiometry is as follows: 1 mol of leucine yields 2 mol of glutamate (2 leucine carbons per glutamate) plus 2 mol of CO2. Comparison of the Leu→Glu pathway in preparations of whole pancreatic segments, isolated acini, and islets of Langerhans localizes it in the acini; relatively high activity is found in cultures of the AR42J cell line and very little in the INS-1 832/13 cell line. Pancreatic tissue glutamate concentration is homeostatically regulated in the range of ∼1-3 μmol/g wet wt. l-Valine and leucine ethyl, benzyl, and tert-butyl esters inhibit the Leu→Glu pathway without decreasing tissue total glutamate.

  1. Leucine supplementation via drinking water reduces atherosclerotic lesions in apoE null mice.

    PubMed

    Zhao, Yang; Dai, Xiao-yan; Zhou, Zhou; Zhao, Ge-xin; Wang, Xian; Xu, Ming-jiang

    2016-02-01

    Recent evidence suggests that the essential amino acid leucine may be involved in systemic cholesterol metabolism. In this study, we investigated the effects of leucine supplementation on the development of atherosclerosis in apoE null mice. ApoE null mice were fed with chow supplemented with leucine (1.5% w/v) in drinking water for 8 week. Aortic atherosclerotic lesions were examined using Oil Red O staining. Plasma lipoprotein-cholesterol levels were measured with fast protein liquid chromatography. Hepatic gene expression was detected using real-time PCR and Western blot analyses. Leucine supplementation resulted in 57.6% reduction of aortic atherosclerotic lesion area in apoE null mice, accompanied by 41.2% decrease of serum LDL-C levels and 40.2% increase of serum HDL-C levels. The body weight, food intake and blood glucose level were not affected by leucine supplementation. Furthermore, leucine supplementation increased the expression of Abcg5 and Abcg8 (that were involved in hepatic cholesterol efflux) by 1.28- and 0.86-fold, respectively, and significantly increased their protein levels. Leucine supplementation also increased the expression of Srebf1, Scd1 and Pgc1b (that were involved in hepatic triglyceride metabolism) by 3.73-, 1.35- and 1.71-fold, respectively. Consequently, leucine supplementation resulted in 51.77% reduction of liver cholesterol content and 2.2-fold increase of liver triglyceride content. Additionally, leucine supplementation did not affect the serum levels of IL-6, IFN-γ, TNF-α, IL-10 and IL-12, but markedly decreased the serum level of MCP-1. Leucine supplementation effectively attenuates atherosclerosis in apoE null mice by improving the plasma lipid profile and reducing systemic inflammation.

  2. Medical management and antiepileptic drugs in hypothalamic hamartoma.

    PubMed

    Helen Cross, J; Spoudeas, Helen

    2017-06-01

    Hypothalamic hamartoma may present with epilepsy, specifically gelastic or dacrystic seizures, or endocrine dysfunction, commonly precocious puberty. The epilepsy in many patients is drug resistant, and has a high association with progressive cognitive, learning and behavioral difficulty. Medical treatment of seizures remains problematic, with many resistant to drug treatment. Surgical resection, or disconnection of the hamartoma provides the optimal chance of seizure control but with a relatively high risk of endocrine dysfunction, the result of interference with the hypothalamic-pituitary axis in many. Careful assessment and monitoring by specialist centers with discussion of optimal intervention is required for individual cases. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

  3. Stimulation of muscle protein synthesis by prolonged parenteral infusion of leucine is dependent on amino acid availability in neonatal pigs

    USDA-ARS?s Scientific Manuscript database

    The postprandial rise in amino acids, particularly leucine, stimulates muscle protein synthesis in neonates. Previously, we showed that a 1-h infusion of leucine increased protein synthesis, but this response was not sustained for 2 h unless the leucine-induced decrease in amino acids was prevented....

  4. Stimulation of skeletal muscle protein synthesis in neonatal pigs by long-term infusion of leucine is amino acid dependent

    USDA-ARS?s Scientific Manuscript database

    Infusing leucine for 1 hr increases skeletal muscle protein synthesis in neonatal pigs, but this is not sustained for 2 h unless the leucine-induced fall in amino acids is prevented. We aimed to determine whether continuous leucine infusion can stimulate protein synthesis for a prolonged period whe...

  5. To ingest or rest? Specialized roles of lateral hypothalamic area neurons in coordinating energy balance

    PubMed Central

    Brown, Juliette A.; Woodworth, Hillary L.; Leinninger, Gina M.

    2015-01-01

    Survival depends on an organism’s ability to sense nutrient status and accordingly regulate intake and energy expenditure behaviors. Uncoupling of energy sensing and behavior, however, underlies energy balance disorders such as anorexia or obesity. The hypothalamus regulates energy balance, and in particular the lateral hypothalamic area (LHA) is poised to coordinate peripheral cues of energy status and behaviors that impact weight, such as drinking, locomotor behavior, arousal/sleep and autonomic output. There are several populations of LHA neurons that are defined by their neuropeptide content and contribute to energy balance. LHA neurons that express the neuropeptides melanin-concentrating hormone (MCH) or orexins/hypocretins (OX) are best characterized and these neurons play important roles in regulating ingestion, arousal, locomotor behavior and autonomic function via distinct neuronal circuits. Recently, another population of LHA neurons containing the neuropeptide Neurotensin (Nts) has been implicated in coordinating anorectic stimuli and behavior to regulate hydration and energy balance. Understanding the specific roles of MCH, OX and Nts neurons in harmonizing energy sensing and behavior thus has the potential to inform pharmacological strategies to modify behaviors and treat energy balance disorders. PMID:25741247

  6. Residues threonine 346 and leucine 352 are critical for the proper function of Bacillus kaustophilus leucine aminopeptidase.

    PubMed

    Chi, Meng-Chun; Huang, Hsien-Ben; Liu, Jai-Shin; Wang, Wen-Ching; Liang, Wan-Chi; Lin, Long-Liu

    2006-07-01

    The importance of Thr-346 and Leu-352 residues in Bacillus kaustophilus leucine aminopeptidase (BkLAP) was explored by site-directed mutagenesis. The impact of substitutions at these positions was evaluated with His6-BkLAP fusion proteins expressed in Escherichia coli. Substitution of Thr-346 with Tyr, Arg, and Leu, respectively, resulted in a dramatic reduction in LAP activity. A complete loss of activity was observed in L352E and L352R variants with the exception of L352 V, which retained approximately 60% of the wild-type activity. Zinc content analysis and protein modeling suggested that Thr-346 and Leu-352 of BkLAP play a role in maintaining the coordination environment for the zinc-binding residues.

  7. Functional diversification within the family of B-GATA transcription factors through the leucine-leucine-methionine domain.

    PubMed

    Behringer, Carina; Bastakis, Emmanouil; Ranftl, Quirin L; Mayer, Klaus F X; Schwechheimer, Claus

    2014-09-01

    The transcription of the Arabidopsis (Arabidopsis thaliana) GATA transcription factors GATA, NITRATE-INDUCIBLE, CARBON METABOLISM-INVOLVED (GNC) and GNC-LIKE (GNL)/CYTOKININ-RESPONSIVE GATA FACTOR1 is controlled by several growth regulatory signals including light and the phytohormones auxin, cytokinin, and gibberellin. To date, GNC and GNL have been attributed functions in the control of germination, greening, flowering time, floral development, senescence, and floral organ abscission. GNC and GNL belong to the 11-member family of B-class GATA transcription factors that are characterized to date solely by their high sequence conservation within the GATA DNA-binding domain. The degree of functional conservation among the various B-class GATA family members is not understood. Here, we identify and examine B-class GATAs from Arabidopsis, tomato (Solanum lycopersicon), Brachypodium (Brachypodium distachyon), and barley (Hordeum vulgare). We find that B-class GATAs from these four species can be subdivided based on their short or long N termini and the presence of the 13-amino acid C-terminal leucine-leucine-methionine (LLM) domain with the conserved motif LLM. Through overexpression analyses and by complementation of a gnc gnl double mutant, we provide evidence that the length of the N terminus may not allow distinguishing between the different B-class GATAs at the functional level. In turn, we find that the presence and absence of the LLM domain in the overexpressors has differential effects on hypocotyl elongation, leaf shape, and petiole length, as well as on gene expression. Thus, our analyses identify the LLM domain as an evolutionarily conserved domain that determines B-class GATA factor identity and provides a further subclassification criterion for this transcription factor family.

  8. Increased IGFBP-1 phosphorylation in response to leucine deprivation is mediated by CK2 and PKC.

    PubMed

    Malkani, Niyati; Biggar, Kyle; Shehab, Majida Abu; Li, Shawn Shun-Cheng; Jansson, Thomas; Gupta, Madhulika B

    2016-04-15

    Insulin-like growth factor binding protein-1 (IGFBP-1), secreted by fetal liver, is a key regulator of IGF-I bioavailability and fetal growth. IGFBP-1 phosphorylation decreases IGF-I bioavailability and diminishes its growth-promoting effects. Growth-restricted fetuses have decreased levels of circulating essential amino acids. We recently showed that IGFBP-1 hyperphosphorylation (pSer101/119/169) in response to leucine deprivation is regulated via activation of the amino acid response (AAR) in HepG2 cells. Here we investigated nutrient-sensitive protein kinases CK2/PKC/PKA in mediating IGFBP-1 phosphorylation in leucine deprivation. We demonstrated that leucine deprivation stimulated CK2 activity (enzymatic assay) and induced IGFBP-1 phosphorylation (immunoblotting/MRM-MS). Inhibition (pharmacological/siRNA) of CK2/PKC, but not PKA, prevented IGFBP-1 hyperphosphorylation in leucine deprivation. PKC inhibition also prevented leucine deprivation-stimulated CK2 activity. Functionally, leucine deprivation decreased IGF-I-induced-IGF-1R autophosphorylation when CK2/PKC were not inhibited. Our data strongly support that PKC promotes leucine deprivation-induced IGFBP-1 hyperphosphorylation via CK2 activation, mechanistically linking decreased amino acid availability and reduced fetal growth.

  9. Leucine deprivation inhibits proliferation and induces apoptosis of human breast cancer cells via fatty acid synthase

    PubMed Central

    Xiao, Fei; Wang, Chunxia; Yin, Hongkun; Yu, Junjie; Chen, Shanghai; Fang, Jing; Guo, Feifan

    2016-01-01

    Substantial studies on fatty acid synthase (FASN) have focused on its role in regulating lipid metabolism and researchers have a great interest in treating cancer with dietary manipulation of amino acids. In the current study, we found that leucine deprivation caused the FASN-dependent anticancer effect. Here we showed that leucine deprivation inhibited cell proliferation and induced apoptosis of MDA-MB-231 and MCF-7 breast cancer cells. In an in vivo tumor xenograft model, the leucine-free diet suppressed the growth of human breast cancer tumors and triggered widespread apoptosis of the cancer cells. Further study indicated that leucine deprivation decreased expression of lipogenic gene FASN in vitro and in vivo. Over-expression of FASN or supplementation of palmitic acid (the product of FASN action) blocked the effects of leucine deprivation on cell proliferation and apoptosis in vitro and in vivo. Moreover, leucine deprivation suppressed the FASN expression via regulating general control non-derepressible (GCN)2 and sterol regulatory element-binding protein 1C (SREBP1C). Taken together, our study represents proof of principle that anticancer effects can be obtained with strategies to deprive tumors of leucine via suppressing FASN expression, which provides important insights in prevention of breast cancer via metabolic intervention. PMID:27579768

  10. L-Leucine for gold nanoparticles synthesis and their cytotoxic effects evaluation.

    PubMed

    Berghian-Grosan, Camelia; Olenic, Liliana; Katona, Gabriel; Perde-Schrepler, Maria; Vulcu, Adriana

    2014-11-01

    This work reports the preparation of water-soluble leucine capped gold nanoparticles by two single-step synthesis methods. The first procedure involves a citrate reduction approach where the citrate is used as reducing agent and leucine as capping/stabilizing agent. Different sizes of gold nanoparticles, citrate reduced and stabilized by leucine, Leu-AuNPs-C, with the mean diameters in the range of 21-56 nm, were obtained by varying the macroscopic parameters such as: concentration of the gold precursor solution, Au (III):citrate molar ratio and leucine pH. In the second procedure, leucine acts both as reducing and stabilizing agent, allowing us to obtain spherical gold nanoparticles, Leu-AuNPs, with a majority of 80 % (with the mean diameter of 63 nm). This proves that leucine is an appropriate reductant for the formation of water-soluble and stable gold nanoparticles colloids. The characterization of the leucine coated gold nanoparticles was carried out by TEM, UV-Vis and FT-IR analysis. The cytotoxic effect of Leu-AuNPs-C and Leu-AuNPs was also evaluated.

  11. Increased IGFBP-1 phosphorylation in response to leucine deprivation is mediated by CK2 and PKC

    PubMed Central

    Malkani, Niyati; Biggar, Kyle; Shehab, Majida Abu; Li, Shawn; Jansson, Thomas; Gupta, Madhulika B.

    2016-01-01

    Insulin-like growth factor binding protein-1 (IGFBP-1), secreted by fetal liver, is a key regulator of IGF-I bioavailability and fetal growth. IGFBP-1 phosphorylation decreases IGF-I bioavailability and diminishes its growth-promoting effects. Growth-restricted fetuses have decreased levels of circulating essential amino acids. We recently showed that IGFBP-1 hyperphosphorylation (pSer101/119/169) in response to leucine deprivation is regulated via activation of the amino acid response (AAR) in HepG2 cells. Here we investigated nutrient-sensitive protein kinases CK2/PKC/PKA in mediating IGFBP-1 phosphorylation in leucine deprivation. We demonstrated that leucine deprivation stimulated CK2 activity (enzymatic assay) and induced IGFBP-1 phosphorylation (immunoblotting/MRM-MS). Inhibition (pharmacological/siRNA) of CK2/PKC, but not PKA, prevented IGFBP-1 hyperphosphorylation in leucine deprivation. PKC inhibition also prevented leucine deprivation-stimulated CK2 activity. Functionally, leucine deprivation decreased IGF-I-induced-IGF-1R autophosphorylation when CK2/PKC were not inhibited. Our data strongly support that PKC promotes leucine deprivation-induced IGFBP-1 hyperphosphorylation via CK2 activation, mechanistically linking decreased amino acid availability and reduced fetal growth. PMID:26733150

  12. Purification and identification of a novel leucine aminopeptidase from Bacillus thuringiensis israelensis.

    PubMed

    Cahan, Rivka; Hetzroni, Efrat; Nisnevitch, Marina; Nitzan, Yeshayahu

    2007-11-01

    A novel leucine aminopeptidase was purified from a Bacillus thuringiensis israelensis (Bti) culture. The purification stages included heating the concentrated supernatant to 65 degrees C for 90 min, anion-exchange chromatography by DEAE cellulose, and hydrophobic chromatography by phenyl Sepharose. The specific activity of leucine aminopeptidase after the hydrophobic chromatography increased by 215.5-fold and the yield was 16%. The molecular weight of the active enzyme was 59 kDa. Mass spectrometry analysis of the 59-kDa leucine aminopeptidase revealed that this protein has at least 41% homology with the cytosol leucine aminopeptidase produced by Bacillus cereus. Maximal leucine aminopeptidase activity occurred at 65 degrees C, pH 10 toward leucine as the amino acid terminus. The enzyme was strongly inhibited by bestatin, dithiothreitol, and 1,10-phenanthroline, indicating that the enzyme might be considered as a metallo-aminopeptidase that has disulfide bonds at the catalytic site or at a region that influences its configuration. Examination of the purified leucine aminopeptidase's effect on the activation of the protoxin Cyt1Aa from Bti revealed that when it acts synergistically with Bti endogenous proteases, it has only a minor role in the processing of Cyt1Aa into an active toxin.

  13. Lack of protective efficacy in buffaloes vaccinated with Fasciola gigantica leucine aminopeptidase and peroxiredoxin recombinant proteins.

    PubMed

    Raina, O K; Nagar, Gaurav; Varghese, Anju; Prajitha, G; Alex, Asha; Maharana, B R; Joshi, P

    2011-06-01

    Gene coding for leucine aminopeptidase (LAP), a metalloprotease, was identified in the tropical liver fluke, Fasciola gigantica; that on sequence analysis showed a close homology (98.6%) with leucine aminopeptidase of the temperate liver fluke, Fasciola hepatica. The recombinant leucine aminopeptidase protein was expressed in Escherichia coli. F. gigantica peroxiredoxin, a hydrogen peroxide scavenger and an immunomodulating protein, was also cloned and expressed in E. coli. A vaccination trial in buffaloes was conducted with these two recombinant proteins, with 150 and 300 μg of leucine aminopeptidase and a cocktail of 150 μg each of recombinant leucine aminopeptidase and peroxiredoxin in three groups, respectively. Both Th1- and Th2-associated humoral immune responses were elicited to immunization with these antigens. A challenge study with 400 metacercariae did not show a significant protection in terms of reduction in the worm burden (8.4%) or anti-fecundity/embryonation effect in the immunized groups, as to the non-immunized control animals. Our observations in this buffalo vaccination trial are contrary to the earlier promise shown by leucine aminopeptidase of F. hepatica as a leading candidate vaccine molecule. Identification of leucine aminopeptidase gene and evaluation of the protein for its protective efficacy in buffaloes is the first scientific report on this protein in F. gigantica.

  14. Leucine Facilitates Insulin Signaling through a Gαi Protein-dependent Signaling Pathway in Hepatocytes*

    PubMed Central

    Yang, Xuefeng; Mei, Shuang; Wang, Xiaolei; Li, Xiang; Liu, Rui; Ma, Yan; Hao, Liping; Yao, Ping; Liu, Liegang; Sun, Xiufa; Gu, Haihua; Liu, Zhenqi; Cao, Wenhong

    2013-01-01

    In this study, we addressed the direct effect of leucine on insulin signaling. In investigating the associated mechanisms, we found that leucine itself does not activate the classical Akt- or ERK1/2 MAP kinase-dependent signaling pathways but can facilitate the insulin-induced phosphorylations of Akt473 and ERK1/2 in a time- and dose-dependent manner in cultured hepatocytes. The leucine-facilitated insulin-induced phosphorylation of Akt at residue 473 was not affected by knocking down the key component of mTORC1 or -2 complexes but was blocked by inhibition of c-Src (PP2), PI3K (LY294002), Gαi protein (pertussis toxin or siRNA against Gαi1 gene, or β-arrestin 2 (siRNA)). Similarly, the leucine-facilitated insulin activation of ERK1/2 was also blunted by pertussis toxin. We further show that leucine facilitated the insulin-mediated suppression of glucose production and expression of key gluconeogenic genes in a Gαi1 protein-dependent manner in cultured primary hepatocytes. Together, these results show that leucine can directly facilitate insulin signaling through a Gαi protein-dependent intracellular signaling pathway. This is the first evidence showing that macronutrients like amino acid leucine can facilitate insulin signaling through G proteins directly. PMID:23404499

  15. Leucine Supplementation Accelerates Connective Tissue Repair of Injured Tibialis Anterior Muscle

    PubMed Central

    Pereira, Marcelo G.; Silva, Meiricris T.; Carlassara, Eduardo O. C.; Gonçalves, Dawit A.; Abrahamsohn, Paulo A.; Kettelhut, Isis C.; Moriscot, Anselmo S.; Aoki, Marcelo S.; Miyabara, Elen H.

    2014-01-01

    This study investigated the effect of leucine supplementation on the skeletal muscle regenerative process, focusing on the remodeling of connective tissue of the fast twitch muscle tibialis anterior (TA). Young male Wistar rats were supplemented with leucine (1.35 g/kg per day); then, TA muscles from the left hind limb were cryolesioned and examined after 10 days. Although leucine supplementation induced increased protein synthesis, it was not sufficient to promote an increase in the cross-sectional area (CSA) of regenerating myofibers (p > 0.05) from TA muscles. However, leucine supplementation reduced the amount of collagen and the activation of phosphorylated transforming growth factor-β receptor type I (TβR-I) and Smad2/3 in regenerating muscles (p < 0.05). Leucine also reduced neonatal myosin heavy chain (MyHC-n) (p < 0.05), increased adult MyHC-II expression (p < 0.05) and prevented the decrease in maximum tetanic strength in regenerating TA muscles (p < 0.05). Our results suggest that leucine supplementation accelerates connective tissue repair and consequent function of regenerating TA through the attenuation of TβR-I and Smad2/3 activation. Therefore, future studies are warranted to investigate leucine supplementation as a nutritional strategy to prevent or attenuate muscle fibrosis in patients with several muscle diseases. PMID:25268835

  16. Effect of L-leucine on oral melphalan kinetics in patients.

    PubMed

    Reece, P A; Dale, B M; Morris, R G; Kotasek, D; Gee, D; Rogerson, S; Sage, R E

    1987-01-01

    Melphalan uptake in the intestine has recently been shown to be an energy-dependent process which is affected by metabolic inhibitors. It is therefore theoretically possible that amino acids in food could reduce melphalan absorption by competing for uptake at the sites of absorption in the intestine. Since L-leucine has been shown to be the most potent inhibitor of melphalan transport into cells in vitro, this amino acid was chosen for the present study in patients. Oral melphalan (4.5 +/- 0.5 mg/m2) was given to ten fasting patients with and without a 2-g oral dose of L-leucine on separate randomized occasions at least 1 week apart. Melphalan plasma levels were measured by high-performance liquid chromatography (HPLC) for 5-h after dosing. L-Leucine plasma levels were measured by HPLC before and at 1 h after dosing. The area under the curve for melphalan was lower in seven of the patients after L-leucine. Plasma L-leucine levels 1 h after melphalan administration were 15.4 +/- 3.7 micrograms/ml fasting and 35.4 +/- 5.2 micrograms/ml after L-leucine. The results indicate that L-leucine can reduce plasma melphalan levels in some patients, probably through a reduction in absorption of the drug from the gastrointestinal tract. However, the effect, like that of food, is highly variable.

  17. Leucine supplementation accelerates connective tissue repair of injured tibialis anterior muscle.

    PubMed

    Pereira, Marcelo G; Silva, Meiricris T; Carlassara, Eduardo O C; Gonçalves, Dawit A; Abrahamsohn, Paulo A; Kettelhut, Isis C; Moriscot, Anselmo S; Aoki, Marcelo S; Miyabara, Elen H

    2014-09-29

    This study investigated the effect of leucine supplementation on the skeletal muscle regenerative process, focusing on the remodeling of connective tissue of the fast twitch muscle tibialis anterior (TA). Young male Wistar rats were supplemented with leucine (1.35 g/kg per day); then, TA muscles from the left hind limb were cryolesioned and examined after 10 days. Although leucine supplementation induced increased protein synthesis, it was not sufficient to promote an increase in the cross-sectional area (CSA) of regenerating myofibers (p > 0.05) from TA muscles. However, leucine supplementation reduced the amount of collagen and the activation of phosphorylated transforming growth factor-β receptor type I (TβR-I) and Smad2/3 in regenerating muscles (p < 0.05). Leucine also reduced neonatal myosin heavy chain (MyHC-n) (p < 0.05), increased adult MyHC-II expression (p < 0.05) and prevented the decrease in maximum tetanic strength in regenerating TA muscles (p < 0.05). Our results suggest that leucine supplementation accelerates connective tissue repair and consequent function of regenerating TA through the attenuation of TβR-I and Smad2/3 activation. Therefore, future studies are warranted to investigate leucine supplementation as a nutritional strategy to prevent or attenuate muscle fibrosis in patients with several muscle diseases.

  18. A Leucine Zipper Motif Essential for Gating of Hyperpolarization-activated Channels*

    PubMed Central

    Wemhöner, Konstantin; Silbernagel, Nicole; Marzian, Stefanie; Netter, Michael F.; Rinné, Susanne; Stansfeld, Phillip J.; Decher, Niels

    2012-01-01

    Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are pacemakers in cardiac myocytes and neurons. Although their membrane topology closely resembles that of voltage-gated K+ channels, the mechanism of their unique gating behavior in response to hyperpolarization is still poorly understood. We have identified a highly conserved leucine zipper motif in the S5 segment of HCN family members. In order to study the role of this motif for channel function, the leucine residues of the zipper were individually mutated to alanine, arginine, or glutamine residues. Leucine zipper mutants traffic to the plasma membrane, but the channels lose their sensitivity to open upon hyperpolarization. Thus, our data indicate that the leucine zipper is an important molecular determinant for hyperpolarization-activated channel gating. Residues of the leucine zipper interact with the adjacent S6 segment of the channel. This interaction is essential for voltage-dependent gating of the channel. The lower part of the leucine zipper, at the intracellular mouth of the channel, is important for stabilizing the closed state. Mutations at these sites increase current amplitudes or result in channels with deficient closing and increased min-Po. Our data are further supported by homology models of the open and closed state of the HCN2 channel pore. Thus, we conclude that the leucine zipper of HCN channels is a major determinant for hyperpolarization-activated channel gating. PMID:23048023

  19. Leucine elicits myotube hypertrophy and enhances maximal contractile force in tissue engineered skeletal muscle in vitro.

    PubMed

    Martin, Neil R W; Turner, Mark C; Farrington, Robert; Player, Darren J; Lewis, Mark P

    2017-10-01

    The amino acid leucine is thought to be important for skeletal muscle growth by virtue of its ability to acutely activate mTORC1 and enhance muscle protein synthesis, yet little data exist regarding its impact on skeletal muscle size and its ability to produce force. We utilized a tissue engineering approach in order to test whether supplementing culture medium with leucine could enhance mTORC1 signaling, myotube growth, and muscle function. Phosphorylation of the mTORC1 target proteins 4EBP-1 and rpS6 and myotube hypertrophy appeared to occur in a dose dependent manner, with 5 and 20 mM of leucine inducing similar effects, which were greater than those seen with 1 mM. Maximal contractile force was also elevated with leucine supplementation; however, although this did not appear to be enhanced with increasing leucine doses, this effect was completely ablated by co-incubation with the mTOR inhibitor rapamycin, showing that the augmented force production in the presence of leucine was mTOR sensitive. Finally, by using electrical stimulation to induce chronic (24 hr) contraction of engineered skeletal muscle constructs, we were able to show that the effects of leucine and muscle contraction are additive, since the two stimuli had cumulative effects on maximal contractile force production. These results extend our current knowledge of the efficacy of leucine as an anabolic nutritional aid showing for the first time that leucine supplementation may augment skeletal muscle functional capacity, and furthermore validates the use of engineered skeletal muscle for highly-controlled investigations into nutritional regulation of muscle physiology. © 2017 The Authors. Journal of Cellular Physiology Published by wiley periodicals, Inc.

  20. Enhanced Incorporation of 3-Hydroxy-4-Methylvalerate Unit into Biosynthetic Polyhydroxyalkanoate Using Leucine as a Precursor

    PubMed Central

    2011-01-01

    Ralstonia eutropha PHB-4 expressing Pseudomonas sp. 61-3 polyhydroxyalkanoate (PHA) synthase 1 (PhaC1Ps) synthesizes PHA copolymer containing 3-hydroxybutyrate (3HB) and a small amount (0.5 mol%) of 3-hydroxy-4-methylvalerate (3H4MV) from fructose as a carbon source. In this study, enhanced incorporation of 3H4MV into PHA was investigated using branched amino acid leucine as a precursor of 3H4MV. Leucine has the same carbon backbone as 3H4MV and is expected to be a natural and self-producible precursor. We found that the incorporation of 3H4MV was enhanced by the supplementation of excess amount (10 g/L) of leucine in the culture medium. This finding indicates that 3H4MV can be derived from leucine. To increase metabolic flux to leucine biosynthesis in the host strain by eliminating the feedback inhibition, the cells were subjected to N-methyl-N'-nitro-N-nitrosoguanidine (NTG) mutagenesis and leucine analog resistant mutants were generated. The mutants showed statistically higher 3H4MV fraction than the parent strain without supplementing leucine. Additionally, by supplying excess amount of leucine, the mutants synthesized 3HB-based PHA copolymer containing 3.1 mol% 3H4MV and 1.2 mol% 3-hydroxyvalerate (3HV) as minor constituents, which significantly affected the thermal properties of the copolymer. This study demonstrates that it is possible to enhance the monomer supply of 3H4MV into PHA by manipulating leucine metabolism. PMID:21906338

  1. Leucine acts as a nutrient signal to stimulate protein synthesis in neonatal pigs

    PubMed Central

    Suryawan, A.; Orellana, R. A.; Fiorotto, M. L.; Davis, T. A.

    2012-01-01

    The postprandial rise in amino acids and insulin independently stimulate protein synthesis in skeletal muscle of piglets. Leucine is an important mediator of the response to amino acids. We have shown that the postprandial rise in leucine, but not isoleucine or valine, acutely stimulates muscle protein synthesis in piglets. Leucine increases muscle protein synthesis by modulating the activation of mammalian target of rapamycin complex 1 (mTORC1) and signaling components of translation initiation. Leucine increases the phosphorylation of mTOR, 70-kDa ribosomal protein S6 kinase-1 (S6K1), eukaryotic initiation factor (eIF) 4E-binding protein-1 (4EBP1), and eIF4G, decreases eIF2α phosphorylation, and increases the association of eIF4E with eIF4G. However, leucine does not affect the upstream activators of mTOR, that is, protein kinase B (PKB), adenosine monophosphate (AMP)-activated protein kinase (AMPK), and tuberous sclerosis complex 1/2 (TSC1/2), or the activation translation of elongation regulator, eukaryotic elongation factor 2 (eEF2). Leucine’s action can be replicated by α-ketoisocaproate (KIC) but not by norleucine. Interference by rapamycin with the raptor-mTOR interaction blocks leucine-induced muscle protein synthesis. The acute leucine-induced stimulation of muscle protein synthesis is not maintained for prolonged periods, despite continued activation of mTOR signaling, because circulating amino acids fall as they are utilized for protein synthesis. However, when circulating amino acid levels are maintained, the leucine-induced stimulation of muscle protein synthesis is maintained for prolonged periods. Thus, leucine acts as a nutrient signal to stimulate translation initiation but whether this translates into a prolonged increase in protein synthesis depends on the sustained availability of all amino acids. PMID:20935141

  2. Design and characterization of short antimicrobial peptides using leucine zipper templates with selectivity towards microorganisms.

    PubMed

    Ahmad, Aqeel; Azmi, Sarfuddin; Srivastava, Saurabh; Kumar, Amit; Tripathi, Jitendra Kumar; Mishra, Nripendra N; Shukla, Praveen K; Ghosh, Jimut Kanti

    2014-11-01

    Design of antimicrobial peptides with selective activity towards microorganisms is an important step towards the development of new antimicrobial agents. Leucine zipper sequence has been implicated in cytotoxic activity of naturally occurring antimicrobial peptides; moreover, this motif has been utilized for the design of novel antimicrobial peptides with modulated cytotoxicity. To understand further the impact of substitution of amino acids at 'a' and/or 'd' position of a leucine zipper sequence of an antimicrobial peptides on its antimicrobial and cytotoxic properties four short peptides (14-residue) were designed on the basis of a leucine zipper sequence without or with replacement of leucine residues in its 'a' and 'd' positions with D-leucine or alanine or proline residue. The original short leucine zipper peptide (SLZP) and its D-leucine substituted analog, DLSA showed comparable activity against the tested Gram-positive and negative bacteria and the fungal strains. The alanine substituted analog (ASA) though showed appreciable activity against the tested bacteria, it showed to some extent lower activity against the tested fungi. However, the proline substituted analog (PSA) showed lower activity against the tested bacterial or fungal strains. Interestingly, DLSA, ASA and PSA showed significantly lower cytotoxicity than SLZP against both human red blood cells (hRBCs) and murine 3T3 cells. Cytotoxic and bactericidal properties of these peptides matched with peptide-induced damage/permeabilization of mammalian cells and bacteria or their mimetic lipid vesicles suggesting cell membrane could be the target of these peptides. As evidenced by tryptophan fluorescence and acrylamide quenching studies the peptides showed similarities either in interaction or in their localization within the bacterial membrane mimetic negatively charged lipid vesicles. Only SLZP showed localization inside the mammalian membrane mimetic zwitterionic lipid vesicles. The results show

  3. Effects of acetyl-DL-leucine in vestibular patients: a clinical study following neurotomy and labyrinthectomy.

    PubMed

    Ferber-Viart, C; Dubreuil, C; Vidal, P P

    2009-01-01

    For 40 years, the amino acid acetyl-DL-leucine (or isoleucine - Tanganil) has been used in clinical practice to reduce imbalance and autonomic manifestations associated with acute vertigo crises. In animal models, acetyl-DL-leucine accelerates vestibular compensation following unilateral labyrinthectomy, and has only minor effects on normal vestibular function. Our work in animal models suggested that acetyl-DL-leucine acted mainly on abnormally hyperpolarized and/or depolarized vestibular neurons by restoring their membrane potential towards a mean value of -65 to -60 mV. Acute vestibular disorders are associated with asymmetrical spontaneous activities of vestibular neurons, so this previous study suggested that acetyl-DL-leucine may reduce acute, vestibular-related imbalances in humans. To test this hypothesis, we investigated the efficacy of acetyl-DL-leucine during the acute stage following neurotomy or labyrinthectomy in patients undergoing surgery for unilateral vestibular acoustic neurinoma, or suffering from unilateral and intractable Ménière's disease. By clinical testing of the vestibular function, patients were categorized according to the degree of compensation of the vestibular deafferentation prior to surgery. For patients who had achieved a close to perfect compensation before surgery, acetyl-DL-leucine had minor or no effect after surgery. For patients who displayed residual vestibular function before surgery, acetyl-DL-leucine eased the static vestibular syndromes, which followed neurotomy. Our findings tend to confirm the view that acetyl-DL-leucine mainly acts, in humans, on abnormally hyperpolarized and/or depolarized vestibular neurons by restoring their membrane potential towards normal values; this is consistent with findings in guinea pigs following unilateral labyrinthectomy. Moreover, it suggests that the degree of caloric paresis of the patients before neurotomy is useful both to predict the outcome of any acute vestibular syndrome

  4. Stereotactic radiofrequency thermocoagulation for hypothalamic hamartoma with intractable gelastic seizures.

    PubMed

    Homma, Junpei; Kameyama, Shigeki; Masuda, Hiroshi; Ueno, Takehiko; Fujimoto, Ayataka; Oishi, Makoto; Fukuda, Masafumi

    2007-08-01

    Management of hypothalamic hamartoma with intractable gelastic epilepsy remains controversial. We have used stereotactic thermocoagulation for treatment of hypothalamic hamartoma with intractable gelastic epilepsy since 1997. Herein, we review our experience in five cases to clarify the usefulness of this treatment. A total of five patients with hypothalamic hamartoma were treated by stereotactic thermocoagulation at our hospital during the period October 1997 through February 2004. In all patients, the hamartoma was less than 10mm in diameter and was located on the floor of the third ventricle with sessile attachment to the wall. To identify ictal onset, chronic intracranial electroencephalography was performed in three patients with the use of a depth electrode implanted in the hamartoma. Attempts were made to induce gelastic seizure by electrical stimulation of the hamartoma in three patients. After magnetic resonance imaging-guided targeting, radiofrequency thermocoagulation of the boundary between the hamartoma and normal hypothalamus was performed to achieve disconnection effects. Marked reductions in seizure frequency were obtained in all cases, with three patients becoming seizure-free after the procedure. No intraoperative complications occurred except in one patient who experienced acute and transient panidrosis with hot flushes during coagulation. Our results suggest that stereotactic thermocoagulation of hypothalamic hamartoma is an acceptable treatment option for patients with intractable gelastic seizures.

  5. Hypothalamic inflammation in the control of metabolic function.

    PubMed

    Valdearcos, Martin; Xu, Allison W; Koliwad, Suneil K

    2015-01-01

    Diet-induced obesity leads to devastating and common chronic diseases, fueling ongoing interest in determining new mechanisms underlying both obesity and its consequences. It is now well known that chronic overnutrition produces a unique form of inflammation in peripheral insulin target tissues, and efforts to limit this inflammation have met with some success in preserving insulin sensitivity in obese individuals. Recently, the activation of inflammatory pathways by dietary excess has also been observed among cells located in the mediobasal hypothalamus, a brain area that exerts central control over peripheral glucose, fat, and energy metabolism. Here we review progress in the field of diet-induced hypothalamic inflammation, drawing key distinctions between metabolic inflammation in the hypothalamus and that occurring in peripheral tissues. We focus on specific stimuli of the inflammatory response, the roles of individual hypothalamic cell types, and the links between hypothalamic inflammation and metabolic function under normal and pathophysiological circumstances. Finally, we explore the concept of controlling hypothalamic inflammation to mitigate metabolic disease.

  6. The effect of spaceflight on retino-hypothalamic tract development

    NASA Technical Reports Server (NTRS)

    Murakami, D. M.; Hoban-Higgins, T. M.; Tang, I. H.; Fuller, C. A.

    1997-01-01

    Researchers examined the effect of late prenatal exposure to microgravity on the development of the retina, retinohypothalamic tract, geniculo-hypothalamic tract, and suprachiasmatic nucleus. Results indicate an effect on c-fos activity in the intergeniculate leaflet between gestational day 20 and postnatal day 8, suggesting a delay in development of the circadian timing system.

  7. The effect of spaceflight on retino-hypothalamic tract development

    NASA Technical Reports Server (NTRS)

    Murakami, D. M.; Hoban-Higgins, T. M.; Tang, I. H.; Fuller, C. A.

    1997-01-01

    Researchers examined the effect of late prenatal exposure to microgravity on the development of the retina, retinohypothalamic tract, geniculo-hypothalamic tract, and suprachiasmatic nucleus. Results indicate an effect on c-fos activity in the intergeniculate leaflet between gestational day 20 and postnatal day 8, suggesting a delay in development of the circadian timing system.

  8. A Hypothalamic Phosphatase Switch Coordinates Energy Expenditure with Feeding.

    PubMed

    Dodd, Garron T; Andrews, Zane B; Simonds, Stephanie E; Michael, Natalie J; DeVeer, Michael; Brüning, Jens C; Spanswick, David; Cowley, Michael A; Tiganis, Tony

    2017-08-01

    Beige adipocytes can interconvert between white and brown-like states and switch between energy storage versus expenditure. Here we report that beige adipocyte plasticity is important for feeding-associated changes in energy expenditure and is coordinated by the hypothalamus and the phosphatase TCPTP. A fasting-induced and glucocorticoid-mediated induction of TCPTP, inhibited insulin signaling in AgRP/NPY neurons, repressed the browning of white fat and decreased energy expenditure. Conversely feeding reduced hypothalamic TCPTP, to increase AgRP/NPY neuronal insulin signaling, white adipose tissue browning and energy expenditure. The feeding-induced repression of hypothalamic TCPTP was defective in obesity. Mice lacking TCPTP in AgRP/NPY neurons were resistant to diet-induced obesity and had increased beige fat activity and energy expenditure. The deletion of hypothalamic TCPTP in obesity restored feeding-induced browning and increased energy expenditure to promote weight loss. Our studies define a hypothalamic switch that coordinates energy expenditure with feeding for the maintenance of energy balance. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Masked function of amino acid sensors on pancreatic hormone secretion in ventromedial hypothalamic (VMH) lesioned rats with marked hyperinsulinemia.

    PubMed

    Ishizuka, Noriko; Tanaka, Katsuaki; Suzuki, Yoko; Kintaka, Yuri; Kinoshita, Ikiko; Hashiguchi, Takeo; Shimizu, Hiroyuki; Senoo, Akira; Imazeki, Nobuo; Kobayashi, Yoko; Arai, Katsumi; Haba, Ryota; Takahashi, Tosei; Sasaki, Kahoru; Kako, Masako; Hayashi, Kaori; Osaka, Toshimasa; Suzuki, Yuichi; Inoue, Shuji

    2012-01-01

    In neural regulation of the endocrine pancreas, there is much evidence to suggest that vagal efferents alter insulin and glucagon secretion, but less information on the effects of vagal afferents. In this study, we investigated the role and function of afferent fibers of the vagus nerve in normal and ventromedial hypothalamic (VMH) lesioned rats with marked hyperinsulinemia. In normal rats, hepatic vagotomy was associated with intraperitoneal (ip) arginine-induced enhancement of insulin and glucagon secretion without an accompanying change in blood glucose levels, ip leucine induced enhancement of insulin secretion accompanied by a decrease in blood glucose levels, and ip alanine-induced enhancement of glucagon secretion accompanied by an increase in blood glucose levels. In VMH lesioned rats with marked hyperinsulinemia, none of these amino acids caused significant changes in insulin and glucagon secretion. We conclude that amino acid sensors in normal rats inhibit excess release of pancreatic hormones induced directly by intake of amino acids, such as that in excess protein ingestion, and maintain blood glucose levels within the normal range. In contrast, in VMH lesioned rats with marked hyperinsulinemia, the function of the amino acid sensors is masked due to the marked hyperinsulinemia in these rats.: © 2012 Asian Oceanian Association for the Study of Obesity . Published by Elsevier Ltd. All rights reserved.

  10. Quantitative requirement of the hatchling green sea turtle, Chelonia mydas, for valine, leucine, isoleucine and phenylalanine.

    PubMed

    Wood, F E; Wood, J R

    1977-08-01

    Hatchling green sea turtles were fed purified diets containing 36% crude protein (N X 6.25) to determine the quantitative requirements for valine, leucine, isoleucine and phenylalanine. Expressed as percentage of total dry diet, the hatchling green sea turtle requires 1.3% valine, 1.6% leucine, 1.0% isoleucine and 1.0% phenylalanine (in the presence of 0.5% tyrosine). Within the range of isoleucine-leucine levels investigated, there was no apparent interrelationship between the quantitative requirements of these two amino acids. Growth rate was decreased at a high level of phenylalanine, 3.0% of the dry diet.

  11. Leucine Transamination Is Lower in Middle-Aged Compared with Younger Adults.

    PubMed

    Tessari, Paolo

    2017-09-20

    Background: Insulin and age affect leucine (and protein) kinetics in vivo. However, to our knowledge, leucine transamination and the effects of insulin have not been studied in participants of different ages.Objective: The aims of the study were to measure whole-body leucine deamination to α-ketoisocaproate (KIC) and KIC reamination to leucine in middle-aged and younger healthy adults, both in the postabsorptive state and after hyperinsulinemia.Methods: Younger (mean ± SE age: 26 ± 2 y) and middle-aged (54 ± 3 y) healthy men and women were enrolled. Isotope dilution methods with 2 independent leucine and KIC tracers, a dual isotope model and the euglycemic, hyperinsulinemic clamp technique, were used.Results: Leucine deamination [expressed as μmol/(kg × min)] was consistently greater than KIC reamination. In middle-aged adults, postabsorptive leucine deamination (0.77 ± 0.05), reamination (0.49 ± 0.04), and net deamination (0.28 ± 0.04) were ∼30% lower than in the younger group (deamination: 1.12 ± 0.07; reamination: 0.70 ± 0.09; net deamination: 0.42 ± 0.04) (P < 0.002, P < 0.05, and P < 0.015, respectively). After the hyperinsulinemic clamp, plasma leucine and KIC concentrations were reduced by ∼50% in both groups. Deamination and reamination also were suppressed by ∼40-50% in both groups (P < 0.001); however, they remained lower [-35% (P = 0.02) and -25% (P = 0.036), respectively] in the middle-aged than in the younger participants. The leucine rate of appearance and its suppression by insulin were similar in the middle-aged and in the younger subjects. By using both the basal and the clamp data, deamination was directly correlated with the plasma leucine concentration (r = 0.61, P < 0.0025) and reamination to that of plasma KIC (r = 0.79, P < 0.00002). Expressing the data relative to lean body mass did not substantially alter the results.Conclusions: Leucine deamination and reamination are lower in middle-aged than in younger adults, both in

  12. Leucine and Protein Metabolism in Obese Zucker Rats

    PubMed Central

    She, Pengxiang; Olson, Kristine C.; Kadota, Yoshihiro; Inukai, Ayami; Shimomura, Yoshiharu; Hoppel, Charles L.; Adams, Sean H.; Kawamata, Yasuko; Matsumoto, Hideki; Sakai, Ryosei; Lang, Charles H.; Lynch, Christopher J.

    2013-01-01

    Branched-chain amino acids (BCAAs) are circulating nutrient signals for protein accretion, however, they increase in obesity and elevations appear to be prognostic of diabetes. To understand the mechanisms whereby obesity affects BCAAs and protein metabolism, we employed metabolomics and measured rates of [1-14C]-leucine metabolism, tissue-specific protein synthesis and branched-chain keto-acid (BCKA) dehydrogenase complex (BCKDC) activities. Male obese Zucker rats (11-weeks old) had increased body weight (BW, 53%), liver (107%) and fat (∼300%), but lower plantaris and gastrocnemius masses (−21–24%). Plasma BCAAs and BCKAs were elevated 45–69% and ∼100%, respectively, in obese rats. Processes facilitating these rises appeared to include increased dietary intake (23%), leucine (Leu) turnover and proteolysis [35% per g fat free mass (FFM), urinary markers of proteolysis: 3-methylhistidine (183%) and 4-hydroxyproline (766%)] and decreased BCKDC per g kidney, heart, gastrocnemius and liver (−47–66%). A process disposing of circulating BCAAs, protein synthesis, was increased 23–29% by obesity in whole-body (FFM corrected), gastrocnemius and liver. Despite the observed decreases in BCKDC activities per gm tissue, rates of whole-body Leu oxidation in obese rats were 22% and 59% higher normalized to BW and FFM, respectively. Consistently, urinary concentrations of eight BCAA catabolism-derived acylcarnitines were also elevated. The unexpected increase in BCAA oxidation may be due to a substrate effect in liver. Supporting this idea, BCKAs were elevated more in liver (193–418%) than plasma or muscle, and per g losses of hepatic BCKDC activities were completely offset by increased liver mass, in contrast to other tissues. In summary, our results indicate that plasma BCKAs may represent a more sensitive metabolic signature for obesity than BCAAs. Processes supporting elevated BCAA]BCKAs in the obese Zucker rat include increased dietary intake, Leu and

  13. Activation of mammalian target of rapamycin signaling in skeletal muscle of neonatal chicks: effects of dietary leucine and age.

    PubMed

    Deng, Huiling; Zheng, Aijuan; Liu, Guohua; Chang, Wenhuan; Zhang, Shu; Cai, Huiyi

    2014-01-01

    The mammalian target of rapamycin (mTOR) signaling pathway is necessary for cellular protein synthesis regulation. Leucine was reported to stimulate muscle protein synthesis in mammalian embryos and neonates, but in higher animals (chickens) the effect of dietary leucine on mTOR signaling is unknown. Thus, we investigated the effects of dietary leucine and age on mRNA expression and phosphorylation of mTOR as well as its downstream targets, ribosomal protein S6 kinase (S6K1) and eukaryotic initiation factor 4E binding protein 1 (4E-BP1) in chick pectoral muscles. One hundred eighty newly hatched male chicks were randomly assigned to 1 of 3 dietary leucine treatment groups (1.43, 1.73, and 2.03% leucine) for 14 d, respectively. Each treatment group consisted of 6 cages with 10 chicks each. On d 3, 7, and 14, plasma insulin and leucine were measured and target gene expression and phosphorylation was assessed. Dietary leucine influenced plasma leucine but not insulin, and plasma leucine and insulin declined with chick age. The mTOR, S6K1, and 4E-BP1 mRNA expression and phosphorylation within chick pectoral muscles were upregulated with increased dietary leucine but downregulated with increased chick age. Thus, high dietary leucine activates target of rapamycin signaling pathways in skeletal muscle of neonatal chicks to stimulate muscle protein synthesis, and this pathway is attenuated with aging.

  14. Craniopharyngioma and hypothalamic injury: latest insights into consequent eating disorders and obesity

    PubMed Central

    Müller, Hermann L.

    2016-01-01

    Purpose of review Hypothalamic alterations, pathological or treatment induced, have major impact on prognosis in craniopharyngioma patients mainly because of consequent hypothalamic obesity. Recent insight in molecular genetics, treatment strategies, risk factors and outcomes associated with hypothalamic obesity provide novel therapeutic perspectives. This review includes relevant publications since 2013. Recent findings Recent findings confirm that alterations in posterior hypothalamic areas because of tumour location and/or treatment-related injuries are associated with severe hypothalamic obesity, reduced overall survival and impaired quality of life in long-term survivors of childhood-onset craniopharyngioma. However, eating disorders are observed because of hypothalamic obesity without clear disease-specific patterns. Treatment options for hypothalamic obesity are very limited. Treatment with invasive, nonreversible bariatric methods such as Roux-en-Y gastric bypass is most efficient in weight reduction, but controversial in the paediatric population because of medical, ethical, and legal considerations. Accordingly, treatment in craniopharyngioma should focus on prevention of (further) hypothalamic injury. Presurgical imaging for grading of hypothalamic involvement should be the basis for hypothalamus-sparing strategies conducted by experienced multidisciplinary teams. Summary Until a nonsurgical therapeutic option for hypothalamic obesity for paediatric patients is found, prevention of hypothalamic injury should be the preferred treatment strategy, conducted exclusively by experienced multidisciplinary teams. PMID:26574645

  15. Glucocorticoid Induced Leucine Zipper inhibits apoptosis of cardiomyocytes by doxorubicin

    SciTech Connect

    Aguilar, David; Strom, Joshua; Chen, Qin M.

    2014-04-01

    Doxorubicin (Dox) is an indispensable chemotherapeutic agent for the treatment of various forms of neoplasia such as lung, breast, ovarian, and bladder cancers. Cardiotoxicity is a major concern for patients receiving Dox therapy. Previous work from our laboratory indicated that glucocorticoids (GCs) alleviate Dox-induced apoptosis in cardiomyocytes. Here we have found Glucocorticoid-Induced Leucine Zipper (GILZ) to be a mediator of GC-induced cytoprotection. GILZ was found to be induced in cardiomyocytes by GC treatment. Knocking down of GILZ using siRNA resulted in cancelation of GC-induced cytoprotection against apoptosis by Dox treatment. Overexpressing GILZ by transfection was able to protect cells from apoptosis induced by Dox as measured by caspase activation, Annexin V binding and morphologic changes. Western blot analyses indicate that GILZ overexpression prevented cytochrome c release from mitochondria and cleavage of caspase-3. When bcl-2 family proteins were examined, we found that GILZ overexpression causes induction of the pro-survival protein Bcl-xL. Since siRNA against Bcl-xL reverses GC induced cytoprotection, Bcl-xL induction represents an important event in GILZ-induced cytoprotection. Our data suggest that GILZ functions as a cytoprotective gene in cardiomyocytes. - Highlights: • Corticosteroids act as a cytoprotective agent in cardiomyocytes • Corticosteroids induce GILZ expression in cardiomyocytes • Elevated GILZ results in resistance against apoptosis induced by doxorubicin • GILZ induces Bcl-xL protein without inducing Bcl-xL mRNA.

  16. Computer-aided design and activity prediction of leucine aminopeptidase inhibitors

    NASA Astrophysics Data System (ADS)

    Grembecka, J.; Sokalski, W. A.; Kafarski, P.

    2000-08-01

    The Ligand Design (LUDI) approach has been used in order to design leucine aminopeptidase inhibitors, predict their activity and analyze their interactions with the enzyme. The investigation was based on the crystal structure of bovine lens leucine aminopeptidase (LAP) complexed with its inhibitor - the phosphonic acid analogue of leucine (LeuP). More than 50 potential leucine aminopeptidase inhibitors have been obtained, including the most potent aminophosphonic LAP inhibitors with experimentally known activity, which have been the subject of more detailed studies. A reasonable agreement between theoretical and experimental activities has been obtained for most of the studied inhibitors. Our results confirm that LUDI is a powerful tool for the design of enzyme inhibitors as well as in the prediction of their activity. In addition, for inhibitor-active site interactions dominated by the electrostatic effects it is possible to improve binding energy estimates by using a more accurate description of inhibitor charge distribution.

  17. The role of hypothalamic mTORC1 signaling in insulin regulation of food intake, body weight, and sympathetic nerve activity in male mice.

    PubMed

    Muta, Kenjiro; Morgan, Donald A; Rahmouni, Kamal

    2015-04-01

    Insulin action in the brain particularly the hypothalamus is critically involved in the regulation of several physiological processes, including energy homeostasis and sympathetic nerve activity, but the underlying mechanisms are poorly understood. The mechanistic target of rapamycin complex 1 (mTORC1) is implicated in the control of diverse cellular functions, including sensing nutrients and energy status. Here, we examined the role of hypothalamic mTORC1 in mediating the anorectic, weight-reducing, and sympathetic effects of central insulin action. In a mouse hypothalamic cell line (GT1-7), insulin treatment increased mTORC1 activity in a time-dependent manner. In addition, intracerebroventricular (ICV) administration of insulin to mice activated mTORC1 pathway in the hypothalamic arcuate nucleus, a key site of central action of insulin. Interestingly, inhibition of hypothalamic mTORC1 with rapamycin reversed the food intake- and body weight-lowering effects of ICV insulin. Rapamycin also abolished the ability of ICV insulin to cause lumbar sympathetic nerve activation. In GT1-7 cells, we found that insulin activation of mTORC1 pathway requires phosphatidylinositol 3-kinase (PI3K). Consistent with this, genetic disruption of PI3K in mice abolished insulin stimulation of hypothalamic mTORC1 signaling as well as the lumbar sympathetic nerve activation evoked by insulin. These results demonstrate the importance of mTORC1 pathway in the hypothalamus in mediating the action of insulin to regulate energy homeostasis and sympathetic nerve traffic. Our data also highlight the key role of PI3K as a link between insulin receptor and mTORC1 signaling in the hypothalamus.

  18. Differential Assimilation of Inorganic Carbon and Leucine by Prochlorococcus in the Oligotrophic North Pacific Subtropical Gyre

    PubMed Central

    Björkman, Karin M.; Church, Matthew J.; Doggett, Joseph K.; Karl, David M.

    2015-01-01

    The light effect on photoheterotrophic processes in Prochlorococcus, and primary and bacterial productivity in the oligotrophic North Pacific Subtropical Gyre was investigated using 14C-bicarbonate and 3H-leucine. Light and dark incubation experiments were conducted in situ throughout the euphotic zone (0–175 m) on nine expeditions to Station ALOHA over a 3-year period. Photosynthetrons were also used to elucidate rate responses in leucine and inorganic carbon assimilation as a function of light intensity. Taxonomic group and cell-specific rates were assessed using flow cytometric sorting. The light:dark assimilation rate ratios of leucine in the top 150 m were ∼7:1 for Prochlorococcus, whereas the light:dark ratios for the non-pigmented bacteria (NPB) were not significant different from 1:1. Prochlorococcus assimilated leucine in the dark at per cell rates similar to the NPB, with a contribution to the total community bacterial production, integrated over the euphotic zone, of approximately 20% in the dark and 60% in the light. Depth-resolved primary productivity and leucine incorporation showed that the ratio of Prochlorococcus leucine:primary production peaked at 100 m then declined steeply below the deep chlorophyll maximum (DCM). The photosynthetron experiments revealed that, for Prochlorococcus at the DCM, the saturating irradiance (Ek) for leucine incorporation was reached at approximately half the light intensity required for light saturation of 14C-bicarbonate assimilation. Additionally, high and low red fluorescing Prochlorococcus populations (HRF and LRF), co-occurring at the DCM, had similar Ek values for their respective substrates, however, maximum assimilation rates, for both leucine and inorganic carbon, were two times greater for HRF cells. Our results show that Prochlorococcus contributes significantly to bacterial production estimates using 3H-leucine, whether or not the incubations are conducted in the dark or light, and this should be

  19. Differential Assimilation of Inorganic Carbon and Leucine by Prochlorococcus in the Oligotrophic North Pacific Subtropical Gyre.

    PubMed

    Björkman, Karin M; Church, Matthew J; Doggett, Joseph K; Karl, David M

    2015-01-01

    The light effect on photoheterotrophic processes in Prochlorococcus, and primary and bacterial productivity in the oligotrophic North Pacific Subtropical Gyre was investigated using (14)C-bicarbonate and (3)H-leucine. Light and dark incubation experiments were conducted in situ throughout the euphotic zone (0-175 m) on nine expeditions to Station ALOHA over a 3-year period. Photosynthetrons were also used to elucidate rate responses in leucine and inorganic carbon assimilation as a function of light intensity. Taxonomic group and cell-specific rates were assessed using flow cytometric sorting. The light:dark assimilation rate ratios of leucine in the top 150 m were ∼7:1 for Prochlorococcus, whereas the light:dark ratios for the non-pigmented bacteria (NPB) were not significant different from 1:1. Prochlorococcus assimilated leucine in the dark at per cell rates similar to the NPB, with a contribution to the total community bacterial production, integrated over the euphotic zone, of approximately 20% in the dark and 60% in the light. Depth-resolved primary productivity and leucine incorporation showed that the ratio of Prochlorococcus leucine:primary production peaked at 100 m then declined steeply below the deep chlorophyll maximum (DCM). The photosynthetron experiments revealed that, for Prochlorococcus at the DCM, the saturating irradiance (E k) for leucine incorporation was reached at approximately half the light intensity required for light saturation of (14)C-bicarbonate assimilation. Additionally, high and low red fluorescing Prochlorococcus populations (HRF and LRF), co-occurring at the DCM, had similar E k values for their respective substrates, however, maximum assimilation rates, for both leucine and inorganic carbon, were two times greater for HRF cells. Our results show that Prochlorococcus contributes significantly to bacterial production estimates using (3)H-leucine, whether or not the incubations are conducted in the dark or light, and this should

  20. Isolation and characterization of awamori yeast mutants with L-leucine accumulation that overproduce isoamyl alcohol.

    PubMed

    Takagi, Hiroshi; Hashida, Keisuke; Watanabe, Daisuke; Nasuno, Ryo; Ohashi, Masataka; Iha, Tomoya; Nezuo, Maiko; Tsukahara, Masatoshi

    2015-02-01

    Awamori shochu is a traditional distilled alcoholic beverage made from steamed rice in Okinawa, Japan. Although it has a unique aroma that is distinguishable from that of other types of shochu, no studies have been reported on the breeding of awamori yeasts. In yeast, isoamyl alcohol (i-AmOH), known as the key flavor of bread, is mainly produced from α-ketoisocaproate in the pathway of L-leucine biosynthesis, which is regulated by end-product inhibition of α-isopropylmalate synthase (IPMS). Here, we isolated mutants resistant to the L-leucine analog 5,5,5-trifluoro-DL-leucine (TFL) derived from diploid awamori yeast of Saccharomyces cerevisiae. Some of the mutants accumulated a greater amount of intracellular L-leucine, and among them, one mutant overproduced i-AmOH in awamori brewing. This mutant carried an allele of the LEU4 gene encoding the Ser542Phe/Ala551Val variant IPMS, which is less sensitive to feedback inhibition by L-leucine. Interestingly, we found that either of the constituent mutations (LEU4(S542F) and LEU4(A551V)) resulted in the TFL tolerance of yeast cells and desensitization to L-leucine feedback inhibition of IPMS, leading to intracellular L-leucine accumulation. Homology modeling also suggested that L-leucine binding was drastically inhibited in the Ser542Phe, Ala551Val, and Ser542Phe/Ala551Val variants due to steric hindrance in the cavity of IPMS. As we expected, awamori yeast cells expressing LEU4(S542F), LEU4(A551V), and LEU4(S542F/A551V) showed a prominent increase in extracellular i-AmOH production, compared with that of cells carrying the vector only. The approach described here could be a practical method for the breeding of novel awamori yeasts to expand the diversity of awamori taste and flavor.

  1. Relationships between leucine and the pancreatic exocrine function for improving starch digestibility in ruminants.

    PubMed

    Liu, K; Liu, Y; Liu, S M; Xu, M; Yu, Z P; Wang, X; Cao, Y C; Yao, J H

    2015-04-01

    Four Holstein heifers (215 ± 7 kg; means ± SD), fitted with one pancreatic pouch, duodenal re-entrant cannulas, and duodenal infusion catheters, were used in this experiment. In phase 1, the 24-h profile of pancreatic fluid was determined. Pancreatic fluid flow peaked 1h after feeding, but peaks of similar magnitude also occurred before the morning feed, necessitating 24-h collection of pancreatic fluid to estimate daily excretion. In phase 2, the effects of duodenal infusions of 0, 10, 20, or 30 g of leucine on pancreatic fluid flow were determined in a 4 × 4 Latin square design. The leucine was infused for 12h in 2,500 mL of the infusate, and samples of pancreatic fluid and jugular blood were collected in 1-h intervals from the beginning of the infusion for 36 h. The results showed that the secretion rate of pancreatic fluid (mL/h) was significantly higher in 10-g leucine group than the other groups (mL/h). Protein concentration (mg/mL) in pancreatic fluid was elevated proportional to the amount of leucine infused. Leucine infusions increased both the concentration (U/mL) and secretion rate (U/h) of α-amylase. Infusion of 10 g of leucine also increased the secretion rates (U/h) of trypsin, chymotrypsin, and lipase, but did not change their concentrations. No significant effects of leucine infusions on plasma glucose and insulin concentrations were found. The results indicate that leucine could act as a nutrient signal to stimulate α-amylase production and pancreatic exocrine function in dairy heifers.

  2. Leucine induced dephosphorylation of Sestrin2 promotes mTORC1 activation.

    PubMed

    Kimball, Scot R; Gordon, Bradley S; Moyer, Jenna E; Dennis, Michael D; Jefferson, Leonard S

    2016-08-01

    The studies described herein were designed to explore the role of Sestrin2 in mediating the selective action of leucine to activate mTORC1. The results demonstrate that Sestrin2 is a phosphoprotein and that its phosphorylation state is responsive to the availability of leucine, but not other essential amino acids. Moreover, leucine availability-induced alterations in Sestrin2 phosphorylation correlated temporally and dose dependently with the activation state of mTORC1, there being a reciprocal relationship between the degree of phosphorylation of Sestrin2 and the extent of repression of mTORC1. With leucine deprivation, Sestrin2 became more highly phosphorylated and interacted more strongly with proteins of the GATOR2 complex. Notably, in cells lacking the protein kinase ULK1, the activation state of mTORC1 was elevated in leucine-deficient medium, such that the effect of re-addition of the amino acid was blunted. In contrast, overexpression of ULK1 led to hyperphosphorylation of Sestrin2 and enhanced its interaction with GATOR2. Neither rapamycin nor Torin2 had any effect on Sestrin2 phosphorylation, suggesting that leucine deprivation-induced repression of mTORC1 was not responsible for the action of ULK1 on Sestrin2. Mass spectrometry analysis of Sestrin2 revealed three phosphorylation sites that are conserved across mammalian species. Mutation of the three sites to phospho-mimetic amino acids in exogenously expressed Sestrin2 promoted its interaction with GATOR2 and dramatically repressed mTORC1 even in the presence of leucine. Overall, the results support a model in which leucine selectively promotes dephosphorylation of Sestrin2, causing it to dissociate from and thereby activate GATOR2, leading to activation of mTORC1. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Stimulation of mTORC1 with L-leucine rescues defects associated with Roberts syndrome.

    PubMed

    Xu, Baoshan; Lee, Kenneth K; Zhang, Lily; Gerton, Jennifer L

    2013-01-01

    Roberts syndrome (RBS) is a human disease characterized by defects in limb and craniofacial development and growth and mental retardation. RBS is caused by mutations in ESCO2, a gene which encodes an acetyltransferase for the cohesin complex. While the essential role of the cohesin complex in chromosome segregation has been well characterized, it plays additional roles in DNA damage repair, chromosome condensation, and gene expression. The developmental phenotypes of Roberts syndrome and other cohesinopathies suggest that gene expression is impaired during embryogenesis. It was previously reported that ribosomal RNA production and protein translation were impaired in immortalized RBS cells. It was speculated that cohesin binding at the rDNA was important for nucleolar form and function. We have explored the hypothesis that reduced ribosome function contributes to RBS in zebrafish models and human cells. Two key pathways that sense cellular stress are the p53 and mTOR pathways. We report that mTOR signaling is inhibited in human RBS cells based on the reduced phosphorylation of the downstream effectors S6K1, S6 and 4EBP1, and this correlates with p53 activation. Nucleoli, the sites of ribosome production, are highly fragmented in RBS cells. We tested the effect of inhibiting p53 or stimulating mTOR in RBS cells. The rescue provided by mTOR activation was more significant, with activation rescuing both cell division and cell death. To study this cohesinopathy in a whole animal model we used ESCO2-mutant and morphant zebrafish embryos, which have developmental defects mimicking RBS. Consistent with RBS patient cells, the ESCO2 mutant embryos show p53 activation and inhibition of the TOR pathway. Stimulation of the TOR pathway with L-leucine rescued many developmental defects of ESCO2-mutant embryos. Our data support the idea that RBS can be attributed in part to defects in ribosome biogenesis, and stimulation of the TOR pathway has therapeutic potential.

  4. Stimulation of mTORC1 with L-leucine Rescues Defects Associated with Roberts Syndrome

    PubMed Central

    Xu, Baoshan; Lee, Kenneth K.; Zhang, Lily; Gerton, Jennifer L.

    2013-01-01

    Roberts syndrome (RBS) is a human disease characterized by defects in limb and craniofacial development and growth and mental retardation. RBS is caused by mutations in ESCO2, a gene which encodes an acetyltransferase for the cohesin complex. While the essential role of the cohesin complex in chromosome segregation has been well characterized, it plays additional roles in DNA damage repair, chromosome condensation, and gene expression. The developmental phenotypes of Roberts syndrome and other cohesinopathies suggest that gene expression is impaired during embryogenesis. It was previously reported that ribosomal RNA production and protein translation were impaired in immortalized RBS cells. It was speculated that cohesin binding at the rDNA was important for nucleolar form and function. We have explored the hypothesis that reduced ribosome function contributes to RBS in zebrafish models and human cells. Two key pathways that sense cellular stress are the p53 and mTOR pathways. We report that mTOR signaling is inhibited in human RBS cells based on the reduced phosphorylation of the downstream effectors S6K1, S6 and 4EBP1, and this correlates with p53 activation. Nucleoli, the sites of ribosome production, are highly fragmented in RBS cells. We tested the effect of inhibiting p53 or stimulating mTOR in RBS cells. The rescue provided by mTOR activation was more significant, with activation rescuing both cell division and cell death. To study this cohesinopathy in a whole animal model we used ESCO2-mutant and morphant zebrafish embryos, which have developmental defects mimicking RBS. Consistent with RBS patient cells, the ESCO2 mutant embryos show p53 activation and inhibition of the TOR pathway. Stimulation of the TOR pathway with L-leucine rescued many developmental defects of ESCO2-mutant embryos. Our data support the idea that RBS can be attributed in part to defects in ribosome biogenesis, and stimulation of the TOR pathway has therapeutic potential. PMID:24098154

  5. IGFBP-1 hyperphosphorylation in response to leucine deprivation is mediated by the AAR pathway

    PubMed Central

    Malkani, Niyati; Jansson, Thomas; Gupta, Madhulika B.

    2017-01-01

    Insulin-like growth factor-1 (IGF-I) is the key regulator of fetal growth. IGF-I bioavailability is markedly diminished by IGF binding protein-1 (IGFBP-1) phosphorylation. Leucine deprivation strongly induces IGFBP-1hyperphosphorylation, and plays an important role in fetal growth restriction (FGR). FGR is characterized by decreased amino acid availability, which activates the amino acid response (AAR) and inhibits the mechanistic target of rapamycin (mTOR) pathway. We investigated the role of AAR and mTOR in mediating IGFBP-1 secretion and phosphorylation in HepG2 cells in leucine deprivation. mTOR inhibition (rapamycin or raptor+rictor siRNA), or activation (DEPTOR siRNA) demonstrated a role of mTOR in leucine deprivation-induced IGFBP-1 secretion but not phosphorylation. When the AAR was blocked (U0126, or ERK/GCN2 siRNA), both IGFBP-1 secretion and phosphorylation (Ser101/Ser119/Ser169) due to leucine deprivation were prevented. CK2 inhibition by TBB also attenuated IGFBP-1 phosphorylation in leucine deprivation. These results suggest that the AAR and mTOR independently regulate IGFBP-1 secretion and phosphorylation in leucine deprivation. PMID:25957086

  6. Changes in leucine uptake in the retina of the hamster after traumatic detachment.

    PubMed

    Yau, K; Li, W W; Yew, D T

    2000-01-01

    Protein metabolism was investigated in detached hamster retinas. By sucking off 0.2 ml of aqueous humor from the anterior chamber through limbic insertion of a 27-gauge needle, a tractional force pulled off the neural retina from the retinal pigment epithelium and created a simple detachment without retinal breaks in the right eyes of the hamsters. The left eyes were left untouched as normal controls and sham controls were induced by simple limbic insertion without suction. The animals were sacrificed at selected intervals of 1, 3, 6, 9, 16, 24, 32 days after the operation. Subsequently, scintillation counting and autoradiography were employed to study retinal protein metabolism using leucine uptake as an index. After tritiated leucine uptake, scintillation counting of radioactive substance indicated that detached retinas had taken in less tritiated leucine than normal controls from day 1 to 6 after the operation, but this change had normalized by day 9. For autoradiography, the change in leucine uptake rate was shown to be different in different layers. All the retinal cells seemed to show a decreased leucine uptake with the exception of the outer nuclear layer, in which leucine appeared to be significantly upregulated. This paper illustrates the patterns of protein metabolism and their change after traumatic detachment as well as their possible recovery. Copyright 2000 S. Karger AG, Basel

  7. Sestrin2 is a leucine sensor for the mTORC1 pathway

    PubMed Central

    Wolfson, Rachel L.; Chantranupong, Lynne; Saxton, Robert A.; Shen, Kuang; Scaria, Sonia M.; Cantor, Jason R.; Sabatini, David M.

    2015-01-01

    Leucine is a proteogenic amino acid that also regulates many aspects of mammalian physiology, in large part by activating the mTOR complex 1 (mTORC1) protein kinase, a master growth controller. Amino acids signal to mTORC1 through the Rag guanine triphosphatases (GTPases). Several factors regulate the Rags, including GATOR1, a GTPase activating protein (GAP); GATOR2, a positive regulator of unknown function; and Sestrin2, a GATOR2-interacting protein that inhibits mTORC1 signaling. We find that leucine, but not arginine, disrupts the Sestrin2-GATOR2 interaction by binding to Sestrin2 with a Kd of 20 µM, which is the leucine concentration that half-maximally activates mTORC1. The leucine-binding capacity of Sestrin2 is required for leucine to activate mTORC1 in cells. These results indicate that Sestrin2 is a leucine sensor for the mTORC1 pathway. PMID:26449471

  8. Metabolic mechanism for L-leucine-induced metabolome to eliminate Streptococcus iniae.

    PubMed

    Du, Chao-Chao; Yang, Manjun; Li, Min-Yi; Yang, Jun; Peng, Bo; Li, Hui; Peng, Xuan-Xian

    2017-03-07

    Crucial metabolites that modulate hosts' metabolome to eliminate bacterial pathogens have been documented, but the metabolic mechanisms are largely unknown. The present study explores the metabolic mechanism for L-leucine-induced metabolome to eliminate Streptococcus iniae in tilapia. GC-MS based metabolomics was used to investigate tilapia liver metabolic profile in the presence of exogenous L-leucine. Thirty-seven metabolites of differential abundance were determined, and eleven metabolic pathways were enriched. Pattern recognition analysis identified serine and proline as crucial metabolites, which are the two metabolites identified in survived tilapias during S. iniae infection, suggesting the two metabolites play crucial roles in L-leucine-induced elimination of the pathogen by the host. Exogenous L-serine reduces mortality of tilapias infected by S. iniae, providing a robust proof for supporting the conclusion. Furthermore, exogenous serine elevates expression of genes Il-1β and Il-8 in tilapia spleen, but not TNFα, CXCR4 and Mx, suggesting the metabolite promotes a phagocytosis role of macrophages, which is consistent with the finding that L-leucine promotes macrophages to kill both Gram-positive and negative bacterial pathogens. Therefore, the ability of phagocytosis enhanced by exogenous L-leucine is partly attributed to elevation of serine. These results demonstrate a metabolic mechanism by which exogenous L-leucine modulates tilapias' metabolome to enhance innate immunity and eliminate pathogens.

  9. Nutritional efficiency of alpha-ketoisocaproate relative to leucine, assessed isotopically

    SciTech Connect

    Kang, C.W.; Walser, M.

    1985-10-01

    The efficiency of alpha-ketoisocaproate as a dietary substitute for leucine was assessed in rats by two techniques: first, the minimal dose of alpha-ketoisocaproate required, as a supplement to a leucine-free diet, to achieve a growth rate as great as animals receiving leucine was found to be between 2.2 and 4.4 times larger. Therefore the nutritional efficiency of alpha-ketoisocaproate lies between 0.23 and 0.46. Second, alpha-(1- UC)-ketoisocaproate and (TH)leucine were administered orally and the ratio of UC/TH incorporated into the leucine of whole-body protein and fibrin was measured. This ratio, divided by the ratio UC/TH injected, was the same in fibrin as in whole-body protein and averaged 0.39. Thus both techniques yield the same value, within the error of measurement, for the relative nutritional efficiency of alpha-ketoisocaproate. The authors also found that alpha-ketoisocaproate feeding at varying dosage did not alter this ratio in whole-body protein, suggesting that neither wide variations in growth rate nor exposure for 10 days to alpha-ketoisocaproate alters the relative rates of utilization (or oxidation) of alpha-ketoisocaproate vs. leucine.

  10. Acute uremia suppresses leucine-induced signal transduction in skeletal muscle.

    PubMed

    McIntire, Kevin L; Chen, Yu; Sood, Sumita; Rabkin, Ralph

    2014-02-01

    Adequate nutrient intake in acute uremia is a key part of patient management especially as food utilization is usually impaired. Leucine is important as it comprises about one-fifth of essential amino acid needs and, apart from serving as a substrate, it directly activates the mTOR signaling pathway stimulating protein synthesis and inhibiting autophagy. Here we tested whether leucine activation of the mTOR signaling pathway in muscle is severely disrupted in acute uremia. Several abnormalities were identified in bilateral ureteral ligated (model of acute uremia) compared to sham-operated pair-fed control rats. Levels of several signaling proteins increased significantly while leucine-induced phosphorylation of mTOR and downstream proteins, 4e-BP1 and S6K1, was completely suppressed. Levels of LC3B-II, a specific autophagosomal membrane-associated protein used as a marker of autophagy, increased threefold in uremia. Furthermore, while leucine suppressed LC3B-II levels in controls, it failed to do so in uremic rats. Muscle IL-6 mRNA levels increased, while IGF-1 mRNA levels decreased in uremia. These findings establish that, in acute uremia, severe resistance to leucine-induced activation of the mTOR anabolic signaling pathway develops. Thus, leucine resistance, together with the reduction in IGF-1 and increase in IL-6 expression, may explain why the anabolic effect of nutritional therapy is diminished in acute uremic patients.

  11. Glial glucokinase expression in adult and post-natal development of the hypothalamic region.

    PubMed

    Millán, Carola; Martínez, Fernando; Cortés-Campos, Christian; Lizama, Isabel; Yañez, Maria Jose; Llanos, Paula; Reinicke, Karin; Rodríguez, Federico; Peruzzo, Bruno; Nualart, Francisco; García, Maria Angeles

    2010-05-25

    It has recently been proposed that hypothalamic glial cells sense glucose levels and release lactate as a signal to activate adjacent neurons. GK (glucokinase), the hexokinase involved in glucose sensing in pancreatic beta-cells, is also expressed in the hypothalamus. However, it has not been clearly determined if glial and/or neuronal cells express this protein. Interestingly, tanycytes, the glia that cover the ventricular walls of the hypothalamus, are in contact with CSF (cerebrospinal fluid), the capillaries of the arcuate nucleus and adjacent neurons; this would be expected for a system that can detect and communicate changes in glucose concentration. Here, we demonstrated by Western-blot analysis, QRT-PCR [quantitative RT-PCR (reverse transcription-PCR)] and in situ hybridization that GK is expressed in tanycytes. Confocal microscopy and immuno-ultrastructural analysis revealed that GK is localized in the nucleus and cytoplasm of beta1-tanycytes. Furthermore, GK expression increased in these cells during the second week of post-natal development. Based on this evidence, we propose that tanycytes mediate, at least in part, the mechanism by which the hypothalamus detects changes in glucose concentrations.

  12. How to find a leucine in a haystack? Structure, ligand recognition and regulation of leucine-aspartic acid (LD) motifs.

    PubMed

    Alam, Tanvir; Alazmi, Meshari; Gao, Xin; Arold, Stefan T

    2014-06-15

    LD motifs (leucine-aspartic acid motifs) are short helical protein-protein interaction motifs that have emerged as key players in connecting cell adhesion with cell motility and survival. LD motifs are required for embryogenesis, wound healing and the evolution of multicellularity. LD motifs also play roles in disease, such as in cancer metastasis or viral infection. First described in the paxillin family of scaffolding proteins, LD motifs and similar acidic LXXLL interaction motifs have been discovered in several other proteins, whereas 16 proteins have been reported to contain LDBDs (LD motif-binding domains). Collectively, structural and functional analyses have revealed a surprising multivalency in LD motif interactions and a wide diversity in LDBD architectures. In the present review, we summarize the molecular basis for function, regulation and selectivity of LD motif interactions that has emerged from more than a decade of research. This overview highlights the intricate multi-level regulation and the inherently noisy and heterogeneous nature of signalling through short protein-protein interaction motifs.

  13. Hypothalamic pituitary adrenal axis and hypothalamic-neurohypophyseal responsiveness in water-deprived rats.

    PubMed

    Grinevich, V; Ma, X M; Verbalis, J; Aguilera, G

    2001-10-01

    The differential effects of osmotic stimulation on magnocellular and parvocellular hypothalamic neurons were studied by analysis of corticotropin-releasing hormone (CRH) and vasopressin (VP) expression in controls and 48-h water-deprived rats subjected to either restraint for 1 h or a single lipopolysaccharide injection (250 microg/100 g). Water deprivation reduced basal CRH mRNA levels but the increments following 4 h of restraint or 6 h lipopolysaccharide (LPS) injection were similar to those in controls. In contrast, water deprivation had no effect on basal VP heteronuclear RNA (hnRNA) and mRNA levels in parvocellular neurons, but responses to restraint or LPS injection were reduced. VP expression in magnocellular paraventricular and supraoptic nuclei, and plasma sodium and vasopressin were higher in water-deprived rats, changes which were unaffected by restraint. LPS injection reduced VP mRNA but not hnRNA levels in magnocellular neurons and increased plasma vasopressin levels only in water-deprived rats independently of changes in plasma sodium. This was accompanied by an increase in vasopressin mRNA content in the posterior pituitary. The data show that the blunted ACTH responses to acute stress during chronic osmotic stimulation are correlated with the inability of parvocellular neurons to increase VP rather than CRH expression. In addition, LPS-induced endotoxemia causes disturbances of the magnocellular vasopressinergic system with an unexpected potentiation of osmotic simulated VP secretion. The lack of increase in VP transcription after LPS and changes in VP mRNA distribution suggest that endotoxemia affect the secretory process at the levels of the neurohypophyseal axon terminal.

  14. Hypothalamic proopiomelanocortin processing and the regulation of energy balance

    PubMed Central

    Wardlaw, Sharon L.

    2011-01-01

    Hypothalamic proopiomelanocortin (POMC) neurons play a key role in regulating energy balance and neuroendocrine function. Much attention has been focused on regulation of POMC gene expression with less emphasis on regulated peptide processing. This is particularly important given the complexity of posttranslational POMC processing which is essential for the generation of biologically active MSH peptides. Mutations that impair POMC sorting and processing are associated with obesity in humans and in animals. Specifically, mutations in the POMC processing enzymes prohormone convertase 1/3 (PCI/3) and in carboxypeptidase E (CPE) and in the α-MSH degrading enzyme, PRCP, are associated with changes in energy balance. There is increasing evidence that POMC processing is regulated with respect to energy balance. Studies have implicated both the leptin and insulin signaling pathways in the regulation of POMC at various steps in the processing pathway. This article will review the role of hypothalamic POMC in regulating energy balance with a focus on POMC processing. PMID:21208604

  15. Hypothalamic ER stress: A bridge between leptin resistance and obesity.

    PubMed

    Ramírez, Sara; Claret, Marc

    2015-06-22

    The prevalence of obesity has increased worldwide at an alarming rate. However, non-invasive pharmacological treatments remain elusive. Leptin resistance is a general feature of obesity, thus strategies aimed at enhancing the sensitivity to this hormone may constitute an excellent therapeutical approach to counteract current obesity epidemics. Nevertheless, the etiology and neuronal basis of leptin resistance remains an enigma. A recent hypothesis gaining substantial experimental support is that hypothalamic endoplasmic reticulum (ER) stress plays a causal role in the development of leptin resistance and obesity. The objective of this review article is to provide an updated view on current evidence connecting hypothalamic ER stress with leptin resistance. We discuss the experimental findings supporting this hypothesis, as well as the potential causes and underlying mechanisms leading to this metabolic disorder. Understanding these mechanisms may provide key insights into the development of novel intervention approaches.

  16. Endocrine changes in histiocytosis of the hypothalamic-pituitary axis.

    PubMed

    Toro Galván, Silvia; Planas Vilaseca, Alejandra; Michalopoulou Alevras, Theodora; Torres Díaz, Alberto; Suárez Balaguer, Javier; Villabona Artero, Carles

    2015-02-01

    Histiocytosis is characterized by proliferation of cells from the mononuclear phagocyte system, and may be divided into Langerhans cell histiocytosis (LCH) and non-Langerhans cell histiocytosis (including Erdheim-Chester disease [ECD]). While diabetes insipidus (DI) is the most common hypothalamic-pituitary consequence, anterior pituitary deficiencies are less known. This study analyzed the frequency and progression of pituitary hormone deficiencies and the radiographic findings in 9 patients (7 with LCH and 2 with ECD) with hypothalamic-pituitary (HP) axis. Eighty-nine percent of patients had DI (62% at diagnosis), and 78% had one or more anterior pituitary deficiencies (71% at diagnosis). HP involvement is relatively common in patients diagnosed with histiocytosis and hormone deficiencies may be present at diagnosis or appear gradually during the course of disease. Regular monitoring of these patients is recommended. Copyright © 2014 SEEN. Published by Elsevier España, S.L.U. All rights reserved.

  17. Hypothalamic pituitary disorders expressed by galactorrhea. A dynamic evaluation.

    PubMed

    Perez-Lopez, F R

    1975-11-01

    Physiologic and pathologic production of milk involves complex relations between the mammary glands, hormones, and the central nervous system. In all the galactorrhea syndromes there is a functional or mechanical problem at the pituitary level, with abnormal secretion or reserve of prolactin secretion. Stimulatory agents of prolactin, like thyrotropin releasing hormone (TRH), chlorpromazine, amnio acids, and insulin, can be helpful in the study of the hypothalamic pituitary functional reserve, while the osmotic tests seem to provide a clear distinction between functional and tumoral causes. The inhibitory agents of prolactin secretion, L-dopa and CB 154, permit the study of the negative control of the hormone. In addition, CB 154 appears to be an effective treatment for functional galactorrhea. Hyperprolactinemia appears to exert an inhibitory influence on gonadotropins. Clomiphene, acting on the hypothalamus, and LHRH, acting on the gonadotropes, permit the assessment of the gonadotropic hypothalamic-hypophyseal axis.

  18. Implications of mitochondrial dynamics on neurodegeneration and on hypothalamic dysfunction

    PubMed Central

    Zorzano, Antonio; Claret, Marc

    2015-01-01

    Mitochondrial dynamics is a term that encompasses the movement of mitochondria along the cytoskeleton, regulation of their architecture, and connectivity mediated by tethering and fusion/fission. The importance of these events in cell physiology and pathology has been partially unraveled with the identification of the genes responsible for the catalysis of mitochondrial fusion and fission. Mutations in two mitochondrial fusion genes (MFN2 and OPA1) cause neurodegenerative diseases, namely Charcot-Marie Tooth type 2A and autosomal dominant optic atrophy (ADOA). Alterations in mitochondrial dynamics may be involved in the pathophysiology of prevalent neurodegenerative conditions. Moreover, impairment of the activity of mitochondrial fusion proteins dysregulates the function of hypothalamic neurons, leading to alterations in food intake and in energy homeostasis. Here we review selected findings in the field of mitochondrial dynamics and their relevance for neurodegeneration and hypothalamic dysfunction. PMID:26113818

  19. Leptin regulates glutamate and glucose transporters in hypothalamic astrocytes

    PubMed Central

    Fuente-Martín, Esther; García-Cáceres, Cristina; Granado, Miriam; de Ceballos, María L.; Sánchez-Garrido, Miguel Ángel; Sarman, Beatrix; Liu, Zhong-Wu; Dietrich, Marcelo O.; Tena-Sempere, Manuel; Argente-Arizón, Pilar; Díaz, Francisca; Argente, Jesús; Horvath, Tamas L.; Chowen, Julie A.

    2012-01-01

    Glial cells perform critical functions that alter the metabolism and activity of neurons, and there is increasing interest in their role in appetite and energy balance. Leptin, a key regulator of appetite and metabolism, has previously been reported to influence glial structural proteins and morphology. Here, we demonstrate that metabolic status and leptin also modify astrocyte-specific glutamate and glucose transporters, indicating that metabolic signals influence synaptic efficacy and glucose uptake and, ultimately, neuronal function. We found that basal and glucose-stimulated electrical activity of hypothalamic proopiomelanocortin (POMC) neurons in mice were altered in the offspring of mothers fed a high-fat diet. In adulthood, increased body weight and fasting also altered the expression of glucose and glutamate transporters. These results demonstrate that whole-organism metabolism alters hypothalamic glial cell activity and suggest that these cells play an important role in the pathology of obesity. PMID:23064363

  20. Hypothalamic-pituitary-adrenal axis function during perinatal depression.

    PubMed

    Gelman, Phillipe Leff; Flores-Ramos, Mónica; López-Martínez, Margarita; Fuentes, Carlos Cruz; Grajeda, Juan Pablo Reyes

    2015-06-01

    Abnormal function of the hypothalamic-pituitary-adrenal (HPA) axis is an important pathological finding in pregnant women exhibiting major depressive disorder. They show high levels of cortisol pro-inflammatory cytokines, hypothalamic-pituitary peptide hormones and catecholamines, along with low dehydroepiandrosterone levels in plasma. During pregnancy, the TH2 balance together with the immune system and placental factors play crucial roles in the development of the fetal allograft to full term. These factors, when altered, may generate a persistent dysfunction of the HPA axis that may lead to an overt transfer of cortisol and toxicity to the fetus at the expense of reduced activity of placental 11β-hydroxysteroid dehydrogenase type 2. Epigenetic modifications also may contribute to the dysregulation of the HPA axis. Affective disorders in pregnant women should be taken seriously, and therapies focused on preventing the deleterious effects of stressors should be implemented to promote the welfare of both mother and baby.

  1. Biomimetic Enamel Regeneration Mediated by Leucine-Rich Amelogenin Peptide.

    PubMed

    Kwak, S Y; Litman, A; Margolis, H C; Yamakoshi, Y; Simmer, J P

    2017-01-01

    We report here a novel biomimetic approach to the regeneration of human enamel. The approach combines the use of inorganic pyrophosphate (PPi) to control the onset and rate of enamel regeneration and the use of leucine-rich amelogenin peptide (LRAP), a nonphosphorylated 56-amino acid alternative splice product of amelogenin, to regulate the shape and orientation of growing enamel crystals. This study builds on our previous findings that show LRAP can effectively guide the formation of ordered arrays of needle-like hydroxyapatite (HA) crystals in vitro and on the known role mineralization inhibitors, like PPi, play in the regulation of mineralized tissue formation. Acid-etched enamel surfaces of extracted human molars, cut perpendicular or parallel to the direction of the enamel rods, were exposed to a PPi-stabilized supersaturated calcium phosphate (CaP) solution containing 0 to 0.06 mg/mL LRAP for 20 h. In the absence of LRAP, PPi inhibition was reversed by the presence of etched enamel surfaces and led to the formation of large, randomly distributed plate-like HA crystals that were weakly attached, regardless of rod orientation. In the presence of 0.04 mg/mL LRAP, however, densely packed mineral layers, comprising bundles of small needle-like HA crystals, formed on etched surfaces that were cut perpendicular to the enamel rods. These crystals were strongly attached, and their arrangement reflected to a significant degree the underlying enamel prism pattern. In contrast, under the same conditions with LRAP, little to no crystal formation was found on enamel surfaces that were cut parallel to the direction of the enamel rods. These results suggest that LRAP preferentially interacts with ab surfaces of mature enamel crystals, inhibiting their directional growth, thus selectively promoting linear growth along the c-axis of enamel crystals. The present findings demonstrate a potential for the development of a new approach to regenerate enamel structure and properties.

  2. Distribution and Evolution of Yersinia Leucine-Rich Repeat Proteins

    PubMed Central

    Hu, Yueming; Huang, He; Hui, Xinjie; Cheng, Xi; White, Aaron P.

    2016-01-01

    Leucine-rich repeat (LRR) proteins are widely distributed in bacteria, playing important roles in various protein-protein interaction processes. In Yersinia, the well-characterized type III secreted effector YopM also belongs to the LRR protein family and is encoded by virulence plasmids. However, little has been known about other LRR members encoded by Yersinia genomes or their evolution. In this study, the Yersinia LRR proteins were comprehensively screened, categorized, and compared. The LRR proteins encoded by chromosomes (LRR1 proteins) appeared to be more similar to each other and different from those encoded by plasmids (LRR2 proteins) with regard to repeat-unit length, amino acid composition profile, and gene expression regulation circuits. LRR1 proteins were also different from LRR2 proteins in that the LRR1 proteins contained an E3 ligase domain (NEL domain) in the C-terminal region or an NEL domain-encoding nucleotide relic in flanking genomic sequences. The LRR1 protein-encoding genes (LRR1 genes) varied dramatically and were categorized into 4 subgroups (a to d), with the LRR1a to -c genes evolving from the same ancestor and LRR1d genes evolving from another ancestor. The consensus and ancestor repeat-unit sequences were inferred for different LRR1 protein subgroups by use of a maximum parsimony modeling strategy. Structural modeling disclosed very similar repeat-unit structures between LRR1 and LRR2 proteins despite the different unit lengths and amino acid compositions. Structural constraints may serve as the driving force to explain the observed mutations in the LRR regions. This study suggests that there may be functional variation and lays the foundation for future experiments investigating the functions of the chromosomally encoded LRR proteins of Yersinia. PMID:27217422

  3. Expression of glucocorticoid-induced leucine zipper (GILZ) in cardiomyocytes.

    PubMed

    Aguilar, David C; Strom, Josh; Xu, Beibei; Kappeler, Kyle; Chen, Qin M

    2013-06-01

    Glucocorticoids (GCs) are frequently prescribed pharmacological agents most notably for their immunosuppressive effects. Endogenous GCs mediate biological processes such as energy metabolism and tissue development. At the cellular level, GCs bind to the glucocorticoid receptor (GR), a cytosolic protein that translocates to the nuclei and functions to alter transcription upon ligand binding. Among a long list of genes activated by GCs is the glucocorticoid-induced leucine zipper (GILZ). GC-induced GILZ expression has been well established in lymphocytes and mediates GC-induced apoptosis. Unlike lymphocytes, cardiomyocytes respond to GCs by gaining resistance against apoptosis. We determined GILZ expression in cardiomyocytes in vivo and in vitro. Expression of GILZ in mouse hearts as a result of GC administration was confirmed by Western blot analyses. GCs induced dose- and time-dependent elevation of GILZ expression in primary cultured rat cardiomyocytes, with dexamethasone (Dex) as low as 0.1 μM being effective. Time course analysis indicated that GILZ protein levels increased at 8 h and peaked at 48 h after exposure to 1 μM Dex. H9c2(2-1) cell line showed a similar response of GILZ induction by Dex as primary cultured rat cardiomyocytes, providing a convenient model for studying the biological significance of GILZ expression. With corticosterone (CT), an endogenous form of corticosteroids in rodents, 0.1-2.5 μM was found to induce GILZ in H9c2(2-1) cells. Time course analysis with 1 μM CT indicated induction of GILZ at 6 h with peak expression at 18 h. Inhibition of the GR by mifepristone led to blunting of GILZ induction by GCs. Our data demonstrate GILZ induction in cardiomyocytes both in vivo and in vitro by GCs, pointing to H9c2(2-1) cells as a valid model for studying the biological function of GILZ in cardiomyocytes.

  4. Expression of Glucocorticoid Induced Leucine Zipper (GILZ) in Cardiomyocytes

    PubMed Central

    Aguilar, David C.; Strom, Josh; Xu, Beibei; Kappeler, Kyle; Chen, Qin M.

    2014-01-01

    Glucocorticoids (GCs) are frequently prescribed pharmacological agents most notably for their immunosuppressive effects. Endogenous GCs mediate biological processes such as energy metabolism and tissue development. At the cellular level, GCs bind to the Glucocorticoid Receptor (GR), a cytosolic protein that translocates to the nuclei and functions to alter transcription upon ligand binding. Amongst a long list of genes activated by GCs is the Glucocorticoid Induced Leucine Zipper (GILZ). GC induced GILZ expression has been well established in lymphocytes and mediates GC induced apoptosis. Unlike lymphocytes, cardiomyocytes respond to GCs by gaining resistance against apoptosis. We determined GILZ expression in cardiomyocytes in vivo and in vitro. Expression of GILZ in mouse hearts as a result of GC administration was confirmed by Western blot analyses. GCs induced dose and time dependent elevation of GILZ expression in primary cultured rat cardiomyocytes, with dexamethasone (Dex) as low as 0.1 M being effective. Time course analysis indicated that GILZ protein levels increased at 8 hr and peaked at 48 hr after exposure to 1 M Dex. H9c2(2-1) cell line showed a similar response of GILZ induction by Dex as primary cultured rat cardiomyocytes, providing a convenient model for studying the biological significance of GILZ expression. With corticosterone (CT), an endogenous form of corticosteroids in rodents, 0.1–2.5 M was found to induce GILZ in H9c2(2-1) cells. Time course analysis with 1 M CT indicated induction of GILZ at 6 hr with peak expression at 18 hr. Inhibition of the GR by mifepristone led to blunting of GILZ induction by GCs. Our data demonstrate GILZ induction in cardiomyocytes both in vivo and in vitro by GCs, pointing to H9c2(2-1) cells as a valid model for studying the biological function of GILZ in cardiomyocytes. PMID:23090754

  5. Molecular cloning and characterization of leucine aminopeptidase from Fasciola gigantica.

    PubMed

    Changklungmoa, Narin; Chaithirayanon, Kulathida; Kueakhai, Pornanan; Meemon, Krai; Riengrojpitak, Suda; Sobhon, Prasert

    2012-07-01

    M17 leucine aminopeptidase (LAP) is one of a family of metalloexopeptidases, of which short peptide fragments are cleaved from the N-terminals. In this study, the full length of cDNA encoding Fasciola gigantica LAP (FgLAP) was cloned from adult parasites. The amino acid sequences of FgLAP showed a high degree of identity (98%) with that from Fasciola hepatica and a low degree of identities (11% and 9%) with those from cattle and human. Phylogenetic analysis revealed that the FgLAP was closely related and grouped with F. hepatica LAP (FhLAP). Northern analysis showed that FgLAP transcriptional products have 1800 base pairs. Analysis by RNA in situ hybridization indicated that LAP gene was expressed in the cecal epithelial cells of adult parasites. A polyclonal antibody to a recombinant FgLAP (rFgLAP) detected the native LAP protein in various developmental stages of the parasite. In a functional test, this rFgLAP displayed aminolytic activity using a fluorogenic Leu-MCA substrate, and was significantly inhibited by bestatin. Its maximum activity was at pH 8.0 and enhanced by Mn(2+) ions. Localization of LAP proteins by immunohistochemistry and immunofluorescence techniques indicated that the enzyme was distributed in the apical cytoplasm of cecal epithelial cells. Because of its important metabolic role and fairly exposed position, FgLAP is a potential drug target and a possible vaccine candidate against fasciolosis. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Differential activities of glucocorticoid-induced leucine zipper protein isoforms.

    PubMed

    Soundararajan, Rama; Wang, Jian; Melters, Daniël; Pearce, David

    2007-12-14

    Glucocorticoid-induced leucine zipper protein (GILZ) is expressed in both epithelial and immune tissues and modulates a variety of cellular functions, including proliferation and epithelial sodium channel (ENaC) activity. A number of reports have described various GILZ activities, focusing on a single isoform with molecular mass of approximately 17 kDa, now termed GILZ1. In GILZ immunoblots using a newly developed antiserum, we detected multiple species in extracts from cultured kidney cells. Mass spectrometric analysis revealed that one of these represented a previously uncharacterized distinct isoform of GILZ, GILZ2. Rapid amplification of cDNA ends was used to clone cDNAs corresponding to four isoforms, which, in addition to GILZ1 and GILZ2, included new isoforms GILZ3 and GILZ4. Heterologous expression of these four GILZ isoforms in cultured cells revealed striking functional differences. Notably, GILZ1 was the only isoform that significantly stimulated ENaC-mediated Na+ current in a kidney collecting duct cell line, although GILZ2 and GILZ3 also stimulated ENaC surface expression in HEK 293 cells. GILZ1 and GILZ3, and to a lesser extent GILZ2, inhibited ERK phosphorylation. Interestingly, GILZ4, which had no effect on either ENaC or ERK, potently suppressed cellular proliferation, as did GILZ1, but not GILZ2 or GILZ3. Finally, rat and mouse tissues all expressed multiple GILZ species but varied in the relative abundance of each. These data suggest that multiple GILZ isoforms are expressed in most cells and tissues and that these play distinct roles in regulating key cellular functions, including proliferation and ion transport. Furthermore, GILZ inhibition of ERK appears to play an essential role in stimulation of cell surface ENaC but not in inhibition of proliferation.

  7. Hypothalamic-pituitary-gonadal endocrine system in the hagfish.

    PubMed

    Nozaki, Masumi

    2013-12-30

    The hypothalamic-pituitary system is considered to be a seminal event that emerged prior to or during the differentiation of the ancestral agnathans (jawless vertebrates). Hagfishes as one of the only two extant members of the class of agnathans are considered the most primitive vertebrates known, living or extinct. Accordingly, studies on their reproduction are important for understanding the evolution and phylogenetic aspects of the vertebrate reproductive endocrine system. In gnathostomes (jawed vertebrates), the hormones of the hypothalamus and pituitary have been extensively studied and shown to have well-defined roles in the control of reproduction. In hagfish, it was thought that they did not have the same neuroendocrine control of reproduction as gnathostomes, since it was not clear whether the hagfish pituitary gland contained tropic hormones of any kind. This review highlights the recent findings of the hypothalamic-pituitary-gonadal endocrine system in the hagfish. In contrast to gnathostomes that have two gonadotropins (GTH: luteinizing hormone and follicle-stimulating hormone), only one pituitary GTH has been identified in the hagfish. Immunohistochemical and functional studies confirmed that this hagfish GTH was significantly correlated with the developmental stages of the gonads and showed the presence of a steroid (estradiol) feedback system at the hypothalamic-pituitary levels. Moreover, while the identity of hypothalamic gonadotropin-releasing hormone (GnRH) has not been determined, immunoreactive (ir) GnRH has been shown in the hagfish brain including seasonal changes of ir-GnRH corresponding to gonadal reproductive stages. In addition, a hagfish PQRFamide peptide was identified and shown to stimulate the expression of hagfish GTHβ mRNA in the hagfish pituitary. These findings provide evidence that there are neuroendocrine-pituitary hormones that share common structure and functional features compared to later evolved vertebrates.

  8. Hypothalamic-Pituitary-Gonadal Endocrine System in the Hagfish

    PubMed Central

    Nozaki, Masumi

    2013-01-01

    The hypothalamic-pituitary system is considered to be a seminal event that emerged prior to or during the differentiation of the ancestral agnathans (jawless vertebrates). Hagfishes as one of the only two extant members of the class of agnathans are considered the most primitive vertebrates known, living or extinct. Accordingly, studies on their reproduction are important for understanding the evolution and phylogenetic aspects of the vertebrate reproductive endocrine system. In gnathostomes (jawed vertebrates), the hormones of the hypothalamus and pituitary have been extensively studied and shown to have well-defined roles in the control of reproduction. In hagfish, it was thought that they did not have the same neuroendocrine control of reproduction as gnathostomes, since it was not clear whether the hagfish pituitary gland contained tropic hormones of any kind. This review highlights the recent findings of the hypothalamic-pituitary-gonadal endocrine system in the hagfish. In contrast to gnathostomes that have two gonadotropins (GTH: luteinizing hormone and follicle-stimulating hormone), only one pituitary GTH has been identified in the hagfish. Immunohistochemical and functional studies confirmed that this hagfish GTH was significantly correlated with the developmental stages of the gonads and showed the presence of a steroid (estradiol) feedback system at the hypothalamic-pituitary levels. Moreover, while the identity of hypothalamic gonadotropin-releasing hormone (GnRH) has not been determined, immunoreactive (ir) GnRH has been shown in the hagfish brain including seasonal changes of ir-GnRH corresponding to gonadal reproductive stages. In addition, a hagfish PQRFamide peptide was identified and shown to stimulate the expression of hagfish GTHβ mRNA in the hagfish pituitary. These findings provide evidence that there are neuroendocrine-pituitary hormones that share common structure and functional features compared to later evolved vertebrates. PMID:24416029

  9. Tryptophan availability modulates serotonin release from rat hypothalamic slices

    NASA Technical Reports Server (NTRS)

    Schaechter, Judith D.; Wurtman, Richard J.

    1989-01-01

    The relationship between the tryptophan availability and serononin release from rat hypothalamus was investigated using a new in vitro technique for estimating rates at which endogenous serotonin is released spontaneously or upon electrical depolarization from hypothalamic slices superfused with a solution containing various amounts of tryptophan. It was found that the spontaneous, as well as electrically induced, release of serotonin from the brain slices exhibited a dose-dependent relationship with the tryptophan concentration of the superfusion medium.

  10. Tryptophan availability modulates serotonin release from rat hypothalamic slices

    NASA Technical Reports Server (NTRS)

    Schaechter, Judith D.; Wurtman, Richard J.

    1989-01-01

    The relationship between the tryptophan availability and serononin release from rat hypothalamus was investigated using a new in vitro technique for estimating rates at which endogenous serotonin is released spontaneously or upon electrical depolarization from hypothalamic slices superfused with a solution containing various amounts of tryptophan. It was found that the spontaneous, as well as electrically induced, release of serotonin from the brain slices exhibited a dose-dependent relationship with the tryptophan concentration of the superfusion medium.

  11. Hypothalamic Inflammation and Energy Balance Disruptions: Spotlight on Chemokines.

    PubMed

    Le Thuc, Ophélia; Stobbe, Katharina; Cansell, Céline; Nahon, Jean-Louis; Blondeau, Nicolas; Rovère, Carole

    2017-01-01

    The hypothalamus is a key brain region in the regulation of energy balance as it controls food intake and both energy storage and expenditure through integration of humoral, neural, and nutrient-related signals and cues. Many years of research have focused on the regulation of energy balance by hypothalamic neurons, but the most recent findings suggest that neurons and glial cells, such as microglia and astrocytes, in the hypothalamus actually orchestrate together several metabolic functions. Because glial cells have been described as mediators of inflammatory processes in the brain, the existence of a causal link between hypothalamic inflammation and the deregulations of feeding behavior, leading to involuntary weight loss or obesity for example, has been suggested. Several inflammatory pathways that could impair the hypothalamic control of energy balance have been studied over the years such as, among others, toll-like receptors and canonical cytokines. Yet, less studied so far, chemokines also represent interesting candidates that could link the aforementioned pathways and the activity of hypothalamic neurons. Indeed, chemokines, in addition to their role in attracting immune cells to the inflamed site, have been suggested to be capable of neuromodulation. Thus, they could disrupt cellular activity together with synthesis and/or secretion of multiple neurotransmitters/mediators involved in the maintenance of energy balance. This review discusses the different inflammatory pathways that have been identified so far in the hypothalamus in the context of feeding behavior and body weight control impairments, with a particular focus on chemokines signaling that opens a new avenue in the understanding of the major role played by inflammation in obesity.

  12. Gliotransmission and brain glucose sensing: critical role of endozepines.

    PubMed

    Lanfray, Damien; Arthaud, Sébastien; Ouellet, Johanne; Compère, Vincent; Do Rego, Jean-Luc; Leprince, Jérôme; Lefranc, Benjamin; Castel, Hélène; Bouchard, Cynthia; Monge-Roffarello, Boris; Richard, Denis; Pelletier, Georges; Vaudry, Hubert; Tonon, Marie-Christine; Morin, Fabrice

    2013-03-01

    Hypothalamic glucose sensing is involved in the control of feeding behavior and peripheral glucose homeostasis, and glial cells are suggested to play an important role in this process. Diazepam-binding inhibitor (DBI) and its processing product the octadecaneuropeptide (ODN), collectively named endozepines, are secreted by astroglia, and ODN is a potent anorexigenic factor. Therefore, we investigated the involvement of endozepines in brain glucose sensing. First, we showed that intracerebroventricular administration of glucose in rats increases DBI expression in hypothalamic glial-like tanycytes. We then demonstrated that glucose stimulates endozepine secretion from hypothalamic explants. Feeding experiments indicate that the anorexigenic effect of central administration of glucose was blunted by coinjection of an ODN antagonist. Conversely, the hyperphagic response elicited by central glucoprivation was suppressed by an ODN agonist. The anorexigenic effects of centrally injected glucose or ODN agonist were suppressed by blockade of the melanocortin-3/4 receptors, suggesting that glucose sensing involves endozepinergic control of the melanocortin pathway. Finally, we found that brain endozepines modulate blood glucose levels, suggesting their involvement in a feedback loop controlling whole-body glucose homeostasis. Collectively, these data indicate that endozepines are a critical relay in brain glucose sensing and potentially new targets in treatment of metabolic disorders.

  13. Hypothalamic stimulation and baroceptor reflex interaction on renal nerve activity.

    NASA Technical Reports Server (NTRS)

    Wilson, M. F.; Ninomiya, I.; Franz, G. N.; Judy, W. V.

    1971-01-01

    The basal level of mean renal nerve activity (MRNA-0) measured in anesthetized cats was found to be modified by the additive interaction of hypothalamic and baroceptor reflex influences. Data were collected with the four major baroceptor nerves either intact or cut, and with mean aortic pressure (MAP) either clamped with a reservoir or raised with l-epinephrine. With intact baroceptor nerves, MRNA stayed essentially constant at level MRNA-0 for MAP below an initial pressure P1, and fell approximately linearly to zero as MAP was raised to P2. Cutting the baroceptor nerves kept MRNA at MRNA-0 (assumed to represent basal central neural output) independent of MAP. The addition of hypothalamic stimulation produced nearly constant increments in MRNA for all pressure levels up to P2, with complete inhibition at some level above P2. The increments in MRNA depended on frequency and location of the stimulus. A piecewise linear model describes MRNA as a linear combination of hypothalamic, basal central neural, and baroceptor reflex activity.

  14. Effects of sugar solutions on hypothalamic appetite regulation.

    PubMed

    Colley, Danielle L; Castonguay, Thomas W

    2015-02-01

    Several hypotheses for the causes of the obesity epidemic in the US have been proposed. One such hypothesis is that dietary intake patterns have significantly shifted to include unprecedented amounts of refined sugar. We set out to determine if different sugars might promote changes in the hypothalamic mechanisms controlling food intake by measuring several hypothalamic peptides subsequent to overnight access to dilute glucose, sucrose, high fructose corn syrup, or fructose solutions. Rats were given access to food, water and a sugar solution for 24h, after which blood and tissues were collected. Fructose access (as opposed to other sugars that were tested) resulted in a doubling of circulating triglycerides. Glucose consumption resulted in upregulation of 7 satiety-related hypothalamic peptides whereas changes in gene expression were mixed for remaining sugars. Also, following multiple verification assays, 6 satiety related peptides were verified as being affected by sugar intake. These data provide evidence that not all sugars are equally effective in affecting the control of intake. Copyright © 2014. Published by Elsevier Inc.

  15. Hypothalamic leptin action is mediated by histone deacetylase 5

    PubMed Central

    Kabra, Dhiraj G.; Pfuhlmann, Katrin; García-Cáceres, Cristina; Schriever, Sonja C.; Casquero García, Veronica; Kebede, Adam Fiseha; Fuente-Martin, Esther; Trivedi, Chitrang; Heppner, Kristy; Uhlenhaut, N. Henriette; Legutko, Beata; Kabra, Uma D.; Gao, Yuanqing; Yi, Chun-Xia; Quarta, Carmelo; Clemmensen, Christoffer; Finan, Brian; Müller, Timo D.; Meyer, Carola W.; Paez-Pereda, Marcelo; Stemmer, Kerstin; Woods, Stephen C.; Perez-Tilve, Diego; Schneider, Robert; Olson, Eric N.; Tschöp, Matthias H.; Pfluger, Paul T.

    2016-01-01

    Hypothalamic leptin signalling has a key role in food intake and energy-balance control and is often impaired in obese individuals. Here we identify histone deacetylase 5 (HDAC5) as a regulator of leptin signalling and organismal energy balance. Global HDAC5 KO mice have increased food intake and greater diet-induced obesity when fed high-fat diet. Pharmacological and genetic inhibition of HDAC5 activity in the mediobasal hypothalamus increases food intake and modulates pathways implicated in leptin signalling. We show HDAC5 directly regulates STAT3 localization and transcriptional activity via reciprocal STAT3 deacetylation at Lys685 and phosphorylation at Tyr705. In vivo, leptin sensitivity is substantially impaired in HDAC5 loss-of-function mice. Hypothalamic HDAC5 overexpression improves leptin action and partially protects against HFD-induced leptin resistance and obesity. Overall, our data suggest that hypothalamic HDAC5 activity is a regulator of leptin signalling that adapts food intake and body weight to our dietary environment. PMID:26923837

  16. EJE PRIZE 2017: Hypothalamic AMPK: a golden target against obesity?

    PubMed

    López, Miguel

    2017-05-01

    AMP-activated protein kinase (AMPK) is a cellular gauge that is activated under conditions, such as low energy, increasing energy production and reducing energy waste. Centrally, the AMPK pathway is a canonical route regulating energy homeostasis, by integrating peripheral signals, such as hormones and metabolites, with neuronal networks. Current evidence links hypothalamic AMPK with feeding, brown adipose tissue (BAT) thermogenesis and browning of white adipose tissue (WAT), as well as muscle metabolism, hepatic function and glucose homeostasis. The relevance of these data is interesting from a therapeutic point of view as several agents with potential anti-obesity and/or antidiabetic effects, some currently in clinical use, such as nicotine, metformin and liraglutide are known to act through AMPK, either peripherally or centrally. Furthermore, the orexigenic and weight-gaining effects of the worldwide use of antipsychotic drugs (APDs), such as olanzapine, are also mediated by hypothalamic AMPK. Overall, this evidence makes hypothalamic AMPK signaling an interesting target for the drug development, with its potential for controlling both sides of the energy balance equation, namely feeding and energy expenditure through defined metabolic pathways. © 2017 The authors.

  17. Role of leptin in energy expenditure: the hypothalamic perspective.

    PubMed

    Pandit, R; Beerens, S; Adan, R A H

    2017-06-01

    The adipocyte-derived hormone leptin is a peripheral signal that informs the brain about the metabolic status of an organism. Although traditionally viewed as an appetite-suppressing hormone, studies in the past decade have highlighted the role of leptin in energy expenditure. Leptin has been shown to increase energy expenditure in particular through its effects on the cardiovascular system and brown adipose tissue (BAT) thermogenesis via the hypothalamus. The current review summarizes the role of leptin signaling in various hypothalamic nuclei and its effects on the sympathetic nervous system to influence blood pressure, heart rate, and BAT thermogenesis. Specifically, the role of leptin signaling on three different hypothalamic nuclei, the dorsomedial hypothalamus, the ventromedial hypothalamus, and the arcuate nucleus, is reviewed. It is known that all of these brain regions influence the sympathetic nervous system activity and thereby regulate BAT thermogenesis and the cardiovascular system. Thus the current work focuses on how leptin signaling in specific neuronal populations within these hypothalamic nuclei influences certain aspects of energy expenditure. Copyright © 2017 the American Physiological Society.

  18. High fructose diet increases anterior hypothalamic alpha 2-adrenoceptors responsiveness.

    PubMed

    Mayer, Marcos A; Höcht, Christian; Opezzo, Javier A; Taira, Carlos A; Fernández, Belisario E; Puyó, Ana M

    2007-08-16

    Activation of alpha(2)-adrenoceptors in the anterior hypothalamic area (AHA) decreases sympathetic nervous system activity and blood pressure. The aim of the present study was to evaluate activity of pre- and postsynaptic alpha(2)-adrenoceptors in the AHA of fructose hypertensive rats (F), an animal model of insulin resistance and hypertension. The AHA of Control (C) and F anaesthetized rats was perfused with Ringer solution in the absence or presence of clonidine (100 or 300 microg ml(-1)) using reverse microdialysis. Clonidine effects on mean arterial pressure (MAP) and heart rate (HR), and on hypothalamic noradrenaline levels were measured along perfusion time. Noradrenaline extracellular levels in the AHA were significantly diminished in F hypertensive rats compared to C animals. The depressor effect of intrahypothalamic perfusion of clonidine on MAP was enhanced in F rats compared with C animals. Intrahypothalamic perfusion of clonidine reduced HR only in F rats. The effect of clonidine on noradrenaline hypothalamic extracellular levels was enhanced in F rats. These results suggest, in our experimental conditions, the existence of an increased responsiveness of pre- and postsynaptic alpha(2)-adrenoceptors in the AHA of F hypertensive rats. This fact could be a consequence of a compensatory supersensitivity of alpha-adrenoceptors due to a decrease in noradrenaline release from nerve terminals located in the AHA.

  19. Hypothalamic stimulation and baroceptor reflex interaction on renal nerve activity.

    NASA Technical Reports Server (NTRS)

    Wilson, M. F.; Ninomiya, I.; Franz, G. N.; Judy, W. V.

    1971-01-01

    The basal level of mean renal nerve activity (MRNA-0) measured in anesthetized cats was found to be modified by the additive interaction of hypothalamic and baroceptor reflex influences. Data were collected with the four major baroceptor nerves either intact or cut, and with mean aortic pressure (MAP) either clamped with a reservoir or raised with l-epinephrine. With intact baroceptor nerves, MRNA stayed essentially constant at level MRNA-0 for MAP below an initial pressure P1, and fell approximately linearly to zero as MAP was raised to P2. Cutting the baroceptor nerves kept MRNA at MRNA-0 (assumed to represent basal central neural output) independent of MAP. The addition of hypothalamic stimulation produced nearly constant increments in MRNA for all pressure levels up to P2, with complete inhibition at some level above P2. The increments in MRNA depended on frequency and location of the stimulus. A piecewise linear model describes MRNA as a linear combination of hypothalamic, basal central neural, and baroceptor reflex activity.

  20. Functional hypothalamic amenorrhoea — diagnostic challenges, monitoring, and treatment.

    PubMed

    Sowińska-Przepiera, Elżbieta; Andrysiak-Mamos, Elżbieta; Jarząbek-Bielecka, Grażyna; Walkowiak, Aleksandra; Osowicz-Korolonek, Lilianna; Syrenicz, Małgorzata; Kędzia, Witold; Syrenicz, Anhelli

    2015-01-01

    Functional hypothalamic amenorrhoea (FHA) is associated with functional inhibition of the hypothalamic-pituitary-ovarian axis. Causes of FHA can be classified into the three groups: 1) stress-related factors, 2) consequences of weight loss and/or underweight, and 3) consequences of physical exercise or practicing sports. Diagnosis of FHA should be based on a history of menstrual disorders. During physical examination, patients with FHA present with secondary and tertiary sex characteristics specific for the pubertal stage preceding development of the condition and with the signs of hypoestrogenism. Laboratory results determine further management of patients with amenorrhea, and thus their correct interpretation is vital for making appropriate therapeutic decisions. Treatment of chronic anovulation, menstrual disorders, and secondary amenorrhea resulting from hypothalamic disorders should be aimed at the elimination of the primary cause, i.e. a decrease in psycho-emotional strain, avoidance of chronic stressors, reduction of physical exercise level, or optimisation of BMI in patients who lose weight. If menses do not resume after a period of six months or primary causative treatment is not possible, neutralisation of hypoestrogenism consequences, especially unfavourable effects on bone metabolism, become the main issue. Previous studies have shown that oestroprogestagen therapy is useful in both the treatment of menstrual disorders and normalisation of bone mineral density. Hormonal preparations should be introduced into therapeutic protocol on an individualised basis.

  1. EJE PRIZE 2017: Hypothalamic AMPK: a golden target against obesity?

    PubMed Central

    2017-01-01

    AMP-activated protein kinase (AMPK) is a cellular gauge that is activated under conditions, such as low energy, increasing energy production and reducing energy waste. Centrally, the AMPK pathway is a canonical route regulating energy homeostasis, by integrating peripheral signals, such as hormones and metabolites, with neuronal networks. Current evidence links hypothalamic AMPK with feeding, brown adipose tissue (BAT) thermogenesis and browning of white adipose tissue (WAT), as well as muscle metabolism, hepatic function and glucose homeostasis. The relevance of these data is interesting from a therapeutic point of view as several agents with potential anti-obesity and/or antidiabetic effects, some currently in clinical use, such as nicotine, metformin and liraglutide are known to act through AMPK, either peripherally or centrally. Furthermore, the orexigenic and weight-gaining effects of the worldwide use of antipsychotic drugs (APDs), such as olanzapine, are also mediated by hypothalamic AMPK. Overall, this evidence makes hypothalamic AMPK signaling an interesting target for the drug development, with its potential for controlling both sides of the energy balance equation, namely feeding and energy expenditure through defined metabolic pathways. PMID:28232370

  2. Early life stress experience may blunt hypothalamic leptin signalling.

    PubMed

    Lee, J H; Yoo, S B; Kim, J Y; Lee, J Y; Kim, B T; Park, K; Jahng, J W

    2017-03-01

    The aim of this study was to investigate whether neonatal maternal separation (MS) - chronic stress experience in early life - affects the anorectic efficacy of leptin in the offspring at adolescence. Sprague-Dawley pups were separated from the dam daily for 3 h during postnatal day 1-14 or left undisturbed as non-handled controls (NH). NH and MS male pups received an intraperitoneal leptin (100 μg/kg) or saline on postnatal day (PND) 28, and then food intake and body weight gain were recorded. The hypothalamic levels of leptin-signalling-related genes, phosphorylated signal transducer and activator of transcription-3 (pSTAT3) and protein-tyrosine phosphatase 1B (PTP1B) were examined at 40 min after a single injection of leptin on PND 39 by immunohistochemistry and Western blot analysis. Leptin-induced suppressions in food intake and weight gain was observed in NH pups, but not in MS. Leptin increased pSTAT3 in the hypothalamic arcuate nucleus of NH pups, but not of MS. Interestingly, basal levels of the hypothalamic PTP1B and pSTAT3 were increased in MS pups compared with NH controls. The results suggest that neonatal MS experience may blunt the anorectic efficacy of leptin later in life, possibly in relation with increased expressions of PTP1B and/or pSTAT3 in the hypothalamus.

  3. Central apelin-13 administration modulates hypothalamic control of feeding.

    PubMed

    Ferrante, C; Orlando, G; Recinella, L; Leone, S; Chiavaroli, A; Di Nisio, C; Shohreh, R; Manippa, F; Ricciuti, A; Vacca, M; Brunetti, L

    2016-01-01

    The 77 amino prepropeptide apelin has been isolated from bovine stomach tissue and several smaller fragments, including apelin-13, showed high affinity for the orphan APJ receptor. The distribution of apelinergic fibers and receptors in the hypothalamus may suggest a role of apelin-13 on energy balance regulation, albeit the studies reporting the acute effects of apelin on feeding control are inconsistent. Considering the possible involvement of apelinergic system on hypothalamic appetite controlling network, in the present study we evaluated in the rat the effects of intrahypothalamic apelin-13 injection on food intake and the involvement of orexigenic and anorexigenic hypothalamic peptides and neurotransmitters. Eighteen rats (6 for each group of treatment) were injected into the ARC with either vehicle or apelin-13 (1-2 μg/rat). Food intake and hypothalamic peptide and neurotransmitter levels were evaluated 2 and 24 h after injection. Compared to vehicle, apelin-13 administration increased food intake both 2 and 24 h following treatment. This effect could be related to inhibited cocaine- and amphetamine-regulated transcript (CART) gene expression and serotonin (5-hydroxytryptamine, 5-HT) synthesis and release, and increased orexin A gene expression in the hypothalamus.

  4. Effects of undernourishment on the hypothalamic orexinergic system.

    PubMed

    Pinos, H; Pérez-Izquierdo, M A; Carrillo, B; Collado, P

    2011-01-10

    The present study examined the effects of a severely restricted diet during the pre- and postnatal periods with later nutritional rehabilitation on orexin hypothalamic neurons in male and female Wistar rats. Immunocytochemistry was used to reveal orexin-immunoreactive (orexin-ir) cells in the ventromedial hypothalamus (VMH), dorsomedial hypothalamus (DMH), lateral hypothalamic area (LH) and the perifornical nucleus (PF). Dietary restriction decreased the number of orexin-ir cells in the LH, whereas DMH or PF orexin-ir populations were not affected in either male or female rats. Nutritional rehabilitation resulted in a differential recovery that depended on the period during which rehabilitation occurred and on the sex of the animal. In summary, our study suggests that the hypothalamic nuclei implicated in eating behavior present a differential vulnerability to adverse environmental conditions during development. Specifically, among the studied nuclei only the LH orexin-ir cells were sensitive to severe food deprivation during development in male and female rats. These results suggest that starvation interferes with developmental events that occur during CNS sexual differentiation. 2010 Elsevier Inc. All rights reserved.

  5. Neurohormones, rikkunshito and hypothalamic neurons interactively control appetite and anorexia.

    PubMed

    Yada, Toshihiko; Kohno, Daisuke; Maejima, Yuko; Sedbazar, Udval; Arai, Takeshi; Toriya, Masako; Maekawa, Fumihiko; Kurita, Hedeharu; Niijima, Akira; Yakabi, Koji

    2012-01-01

    Ghrelin is the orexigenic peptide produced in the periphery, and its plasma level shows remarkable pre/postprandial changes. Ghrelin is considered a pivotal signal to the brain to stimulate feeding. Hence, characterizing the target neurons for ghrelin in the hypothalamic feeding center and the signaling cascade in the target neurons are essential for understanding the mechanisms regulating appetite. Anorexia and cachexia associated with gastric surgery, stress-related diseases, and use of anti-cancer drugs cause the health problems, markedly deteriorating the quality of life. The anorexia involves several neurotransmitters and neuropeptides in the hypothalamic feeding center, in which corticotropin-releasing hormone (CRH), urocortine, serotonin (5HT) and brain-derived neurotrophic factor (BDNF) play a pivotal role. A Japanese herbal medicine, rikkunshito, has been reported to ameliorate the anorexia by promoting the appetite. This review describes 1) the interaction of ghrelin with the orexigenic neuropeptide Y (NPY) neurons in the hypothalamic arcuate nucleus (ARC) and underlying signaling cascade in NPY neurons, 2) the anorectic pathway driven by BDNF-CRH/urocortine and 5HTCRH/ urocortine pathways, 3) the effect of rikkunshito on the interaction of ghrelin and NPY neurons in ARC, and 4) the effect of rikkunshito on the interaction of 5HT on CRH neurons in paraventricular nucleus (PVN).

  6. Leucyl-tRNA synthetase: double duty in amino acid sensing.

    PubMed

    Durán, Raúl V; Hall, Michael N

    2012-08-01

    The cellular response to amino acids is controlled at the molecular level by TORC1. While many of the elements that participate in TORC1 signaling are known, we still have no clear idea how cells sense amino acids. Two recent studies found that leucyl-tRNA synthetase (LRS) is a leucine sensor for TORC1, in both yeast and mammalian cells.

  7. Model of how plants sense zinc deficiency.

    PubMed

    Assunção, Ana G L; Persson, Daniel P; Husted, Søren; Schjørring, Jan K; Alexander, Ross D; Aarts, Mark G M

    2013-09-01

    Plants are capable of inducing a range of physico-chemical and microbial modifications of the rhizosphere which can mobilize mineral nutrients or prevent toxic elements from entering the roots. Understanding how plants sense and adapt to variations in nutrient availability is essential in order to develop plant-based solutions addressing nutrient-use-efficiency and adaptation to nutrient-limited or -toxic soils. Recently two transcription factors of the bZIP family (basic-region leucine zipper) have been identified in Arabidopsis and shown to be pivotal in the adaptation response to zinc deficiency. They represent not only the first regulators of zinc homeostasis identified in plants, but also a very promising starting-point that can provide new insights into the molecular basis of how plants sense and adapt to the stress of zinc deficiency. Considering the available information thus far we propose in this review a putative model of how plants sense zinc deficiency.

  8. Simulations of potentials of mean force for separating a leucine zipper dimer and the basic region of a basic region leucine zipper dimer.

    PubMed

    Cukier, Robert I

    2014-09-04

    Basic region leucine zipper (bZIP) transcription factors involved in DNA recognition are dimeric proteins. The monomers consist of two subdomains, a leucine zipper sequence responsible for dimerization and a highly basic DNA recognition sequence. Leucine zippers are strongly dimerized, and in a bZIP, the basic region can, in the absence of DNA, undergo extensive relative monomer-to-monomer fluctuations. In this work, LZ and bZIP potentials of mean force (PMFs), which provide free energies along reaction coordinates, are simulated with a distance replica exchange method. The method uses restraint potentials to provide sampling along a reaction coordinate and enhances configuration space exploration by exchanging information between neighboring restraint potential configurations. Restraint potentials that are constructed from sums over a number of atom distances are employed. Their use requires a modification of the Weighted Histogram Analysis Method (WHAM) procedure to combine and unbias the data from the different restraint-potential-biased window densities to provide a PMF. These methods are first used to obtain a PMF for separating a leucine zipper (GCN4-p1) of the yeast transcriptional activator GCN4. The PMF indicates a very strong binding free energy that only weakens when the monomers are separated by about 12 Å, which is about 6 Å beyond their bound, dimer equilibrium distance. PMFs are also obtained for separating the basic subdomain monomer parts of the GCN4 bZIP transcriptional factor, in the absence of DNA. In a monomer separation range spanning the open, crystal-based structure to closer configurations, the basic subdomain PMF is quite flat, implying essentially thermal sampling in this distance range. A PMF generated starting from a "collapsed" state, taken from a previous simulation ( J. Phys. Chem. B 2012 , 116 , 6071 ), where collapsed refers to the feature that the basic subdomain monomers are also effectively dimerized, shows that this state is

  9. Orexin-A suppresses postischemic glucose intolerance and neuronal damage through hypothalamic brain-derived neurotrophic factor.

    PubMed

    Harada, Shinichi; Yamazaki, Yui; Tokuyama, Shogo

    2013-01-01

    Orexin-A (a glucose-sensing neuropeptide in the hypothalamus) and brain-derived neurotrophic factor (BDNF; a member of the neurotrophin family) play roles in many physiologic functions, including regulation of glucose metabolism. We previously showed that the development of postischemic glucose intolerance is one of the triggers of ischemic neuronal damage. The aim of this study was to determine whether there was an interaction between orexin-A and BDNF functions in the hypothalamus after cerebral ischemic stress. Male ddY mice were subjected to 2 hours of middle cerebral artery occlusion (MCAO). Neuronal damage was estimated by histologic and behavioral analyses. Expression of protein levels was analyzed by Western blot. Small interfering RNA directed BDNF, orexin-A, and SB334867 [N-(2-methyl-6-benzoxazolyl)-N'-1,5-naphthyridin-4-yl urea; a specific orexin-1 receptor antagonist] were administered directly into the hypothalamus. The level of hypothalamic orexin-A, detected by immunohistochemistry, was decreased on day 1 after MCAO. Intrahypothalamic administration of orexin-A (1 or 5 pmol/mouse) significantly and dose-dependently suppressed the development of postischemic glucose intolerance on day 1 and development of neuronal damage on day 3. The MCAO-induced decrease in insulin receptor levels in the liver and skeletal muscle on day 1 was recovered to control levels by orexin-A, and this effect of orexin-A was reversed by the administration of SB334867 as well as by hypothalamic BDNF knockdown. These results suggest that suppression of postischemic glucose intolerance by orexin-A assists in the prevention of cerebral ischemic neuronal damage. In addition, hypothalamic BDNF may play an important role in this effect of orexin-A.

  10. Central NUCB2/Nesfatin-1-expressing neurones belong to the hypothalamic-brainstem circuitry activated by hypoglycaemia.

    PubMed

    Bonnet, M S; Djelloul, M; Tillement, V; Tardivel, C; Mounien, L; Trouslard, J; Troadec, J-D; Dallaporta, M

    2013-01-01

    Nesfatin-1 is a recently identified 82 amino acid peptide shown to have an anorexigenic effect on rodents when administrered centrally and peripherally. Nesfatin-1 is expressed not only in neurones of various brain areas, including the hypothalamic and brainstem nuclei, but also in peripheral organs, such as the stomach and the pancreas. Nesfatinergic neurones were reported to participate in the regulation of satiety signals and in the responses to other stimuli, including restraint stress, abdominal surgery, and lipopolysaccharide-induced inflammation. The present study aimed to investigate whether NUCB2/nesfatin-1 expressing neurones also take part in the central signalling activated in response to hypoglycaemia and therefore are involved in central glucose sensing. Using immunolabelling methods based on the detection of the neuronal activation marker c-Fos and of nesfatin-1, we showed that peripheral injection of insulin induced a strong activation of nesfatin-1-expressing neurones in the brain vagal-regulatory nuclei, including the arcuate nucleus, paraventricular nucleus, lateral hypothalamic area, dorsal motor nucleus of the vagus (DMNX) and nucleus of the tractus solitarius. In response to intracellular glucopaenia induced by i.p. or i.c.v. 2-deoxyglucose injection, the c-Fos/nesfatin-1 colocalisations observed at the hypothalamic and brainstem levels were similar to those observed after insulin-induced hypoglycaemia. Moreover, using Fluorogold as a retrograde tracer, we showed that nesfatinergic preganglionic DMNX neurones activated by hypoglycaemia target the stomach and the pancreas. Taken together, these results suggest that a subpopulation of nesfatinergic neurones belongs to the central network activated by hypoglycaemia, and that nesfatin-1 participates in the triggering of physiological and hormonal counter-regulations observed in response to hypoglycaemia. © 2012 British Society for Neuroendocrinology.

  11. Investigations on the humidity-induced transformations of salbutamol sulphate particles coated with L-leucine.

    PubMed

    Raula, Janne; Thielmann, Frank; Kansikas, Jarno; Hietala, Sami; Annala, Minna; Seppälä, Jukka; Lähde, Anna; Kauppinen, Esko I

    2008-10-01

    The crystallization and structural integrity of micron-sized inhalable salbutamol sulphate particles coated with L-leucine by different methods are investigated at different humidities. The influence of the L-leucine coating on the crystallization of salbutamol sulphate beneath the coating layer is explored. The coated particles are prepared by an aerosol flow reactor method, the formation of the L-leucine coating being controlled by the saturation conditions of the L-leucine. The coating is formed by solute diffusion within a droplet and/or by vapour deposition of L-leucine. The powders are humidified at 0%, 44%, 65% and 75% of relative humidity and the changes in physical properties of the powders are investigated with dynamic vapour sorption analysis (DVS), a differential scanning calorimeter (DSC), and a scanning electron microscope (SEM). Visual observation show that all the coated particles preserve their structural integrity whereas uncoated salbutamol sulphate particles are unstable at 65% of relative humidity. The coating layer formed by diffusion performs best in terms of its physical stability against moisture and moisture-induced crystallization. The degree of crystallization of salbutamol in the as-prepared powders is within the range 24-35%. The maximum degree of crystallization after drying ranges from 55 to 73% when the salbutamol crystallizes with the aid of moisture. In addition to providing protection against moisture, the L-leucine coating also stabilizes the particle structure against heat at temperatures up to 250 degrees C. In order to preserve good flowability together with good physical stability, the best coating would contain two L-leucine layers, the inner layer being formed by diffusion (physical stability) and the outer layer by vapour deposition (flowability).

  12. Protein Ingestion Induces Muscle Insulin Resistance Independent of Leucine-Mediated mTOR Activation

    PubMed Central

    Smith, Gordon I.; Yoshino, Jun; Stromsdorfer, Kelly L.; Klein, Seth J.; Magkos, Faidon; Reeds, Dominic N.; Klein, Samuel

    2015-01-01

    Increased plasma branched-chain amino acid concentrations are associated with insulin resistance, and intravenous amino acid infusion blunts insulin-mediated glucose disposal. We tested the hypothesis that protein ingestion impairs insulin-mediated glucose disposal by leucine-mediated mTOR signaling, which can inhibit AKT. We measured glucose disposal and muscle p-mTORSer2448, p-AKTSer473, and p-AKTThr308 in 22 women during a hyperinsulinemic-euglycemic clamp procedure with and without concomitant ingestion of whey protein (0.6 g/kg fat-free mass; n = 11) or leucine that matched the amount given with whey protein (n = 11). Both whey protein and leucine ingestion raised plasma leucine concentration by approximately twofold and muscle p-mTORSer2448 by ∼30% above the values observed in the control (no amino acid ingestion) studies; p-AKTSer473 and p-AKTThr308 were not affected by whey protein or leucine ingestion. Whey protein ingestion decreased insulin-mediated glucose disposal (median 38.8 [quartiles 30.8, 61.8] vs. 51.9 [41.0, 77.3] µmol glucose/µU insulin · mL−1 · min−1; P < 0.01), whereas ingestion of leucine did not (52.3 [43.3, 65.4] vs. 52.3 [43.9, 73.2]). These results indicate that 1) protein ingestion causes insulin resistance and could be an important regulator of postprandial glucose homeostasis and 2) the insulin-desensitizing effect of protein ingestion is not due to inhibition of AKT by leucine-mediated mTOR signaling. PMID:25475435

  13. Protein Ingestion Induces Muscle Insulin Resistance Independent of Leucine-Mediated mTOR Activation.

    PubMed

    Smith, Gordon I; Yoshino, Jun; Stromsdorfer, Kelly L; Klein, Seth J; Magkos, Faidon; Reeds, Dominic N; Klein, Samuel; Mittendorfer, Bettina

    2015-05-01

    Increased plasma branched-chain amino acid concentrations are associated with insulin resistance, and intravenous amino acid infusion blunts insulin-mediated glucose disposal. We tested the hypothesis that protein ingestion impairs insulin-mediated glucose disposal by leucine-mediated mTOR signaling, which can inhibit AKT. We measured glucose disposal and muscle p-mTOR(Ser2448), p-AKT(Ser473), and p-AKT(Thr308) in 22 women during a hyperinsulinemic-euglycemic clamp procedure with and without concomitant ingestion of whey protein (0.6 g/kg fat-free mass; n = 11) or leucine that matched the amount given with whey protein (n = 11). Both whey protein and leucine ingestion raised plasma leucine concentration by approximately twofold and muscle p-mTOR(Ser2448) by ∼30% above the values observed in the control (no amino acid ingestion) studies; p-AKT(Ser473) and p-AKT(Thr308) were not affected by whey protein or leucine ingestion. Whey protein ingestion decreased insulin-mediated glucose disposal (median 38.8 [quartiles 30.8, 61.8] vs. 51.9 [41.0, 77.3] µmol glucose/µU insulin · mL(-1) · min(-1); P < 0.01), whereas ingestion of leucine did not (52.3 [43.3, 65.4] vs. 52.3 [43.9, 73.2]). These results indicate that 1) protein ingestion causes insulin resistance and could be an important regulator of postprandial glucose homeostasis and 2) the insulin-desensitizing effect of protein ingestion is not due to inhibition of AKT by leucine-mediated mTOR signaling.

  14. [Hypothalamic inflammation and energy balance deregulations: focus on chemokines.

    PubMed

    Le Thuc, Ophélia; Rovère, Carole

    2016-01-01

    The hypothalamus is a key brain region in the regulation of energy balance. It especially controls food intake and both energy storage and expenditure through integration of humoral, neural and nutrient-related signals and cues. Hypothalamic neurons and glial cells act jointly to orchestrate, both spatially and temporally, regulated metabolic functions of the hypothalamus. Thus, the existence of a causal link between hypothalamic inflammation and deregulations of feeding behavior, such as involuntary weight-loss or obesity, has been suggested. Among the inflammatory mediators that could induce deregulations of hypothalamic control of the energy balance, chemokines represent interesting candidates. Indeed, chemokines, primarily known for their chemoattractant role of immune cells to the inflamed site, have also been suggested capable of neuromodulation. Thus, chemokines could disrupt cellular activity together with synthesis and/or secretion of multiple neurotransmitters/mediators that are involved in the maintenance of energy balance. Here, we relate, on one hand, recent results showing the primary role of the central chemokinergic signaling CCL2/CCR2 for metabolic and behavioral adaptation to high-grade inflammation, especially loss of appetite and weight, through its activity on hypothalamic neurons producing the orexigenic peptide Melanin-Concentrating Hormone (MCH) and, on the other hand, results that suggest that chemokines could also deregulate hypothalamic neuropeptidergic circuits to induce an opposite phenotype and eventually participate in the onset/development of obesity. In more details, we will emphasize a study recently showing, in a model of high-grade acute inflammation of LPS injection in mice, that central CCL2/CCR2 signaling is of primary importance for several aspects explaining weight loss associated with inflammation: after LPS injection, animals lose weight, reduce their food intake, increase their fat oxidation (thus energy consumption from

  15. Glucokinase inhibitor glucosamine stimulates feeding and activates hypothalamic neuropeptide Y and orexin neurons.

    PubMed

    Zhou, Ligang; Yueh, Chen-Yu; Lam, Daniel D; Shaw, Jill; Osundiji, Mayowa; Garfield, Alastair S; Evans, Mark; Heisler, Lora K

    2011-09-12

    Maintaining glucose levels within the appropriate physiological range is necessary for survival. The identification of specific neuronal populations, within discreet brain regions, sensitive to changes in glucose concentration has led to the hypothesis of a central glucose-sensing system capable of directly modulating feeding behaviour. Glucokinase (GK) has been identified as a glucose-sensor responsible for detecting such changes both within the brain and the periphery. We previously reported that antagonism of centrally expressed GK by administration of glucosamine (GSN) was sufficient to induce protective glucoprivic feeding in rats. Here we examine a neurochemical mechanism underlying this effect and report that GSN stimulated food intake is highly correlated with the induction of the neuronal activation marker cFOS within two nuclei with a demonstrated role in central glucose sensing and appetite, the arcuate nucleus of the hypothalamus (ARC) and lateral hypothalamic area (LHA). Furthermore, GSN stimulated cFOS within the ARC was observed in orexigenic neurons expressing the endogenous melanocortin receptor antagonist agouti-related peptide (AgRP) and neuropeptide Y (NPY), but not those expressing the anorectic endogenous melanocortin receptor agonist alpha-melanocyte stimulating hormone (α-MSH). In the LHA, GSN stimulated cFOS was found within arousal and feeding associated orexin/hypocretin (ORX), but not orexigenic melanin-concentrating hormone (MCH) expressing neurons. Our data suggest that GK within these specific feeding and arousal related populations of AgRP/NPY and ORX neurons may play a modulatory role in the sensing of and appetitive response to hypoglycaemia. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Phosphorylation of 4EBP by oral leucine administration was suppressed in the skeletal muscle of PGC-1α knockout mice.

    PubMed

    Yoshimura, Ryoji; Minami, Kimiko; Matsuda, Junichiro; Sawada, Naoki; Miura, Shinji; Kamei, Yasutomi

    2016-01-01

    Leucine is known to increase mTOR-mediated phosphorylation of 4EBP. In this study, leucine was administered to skeletal muscle-PGC-1α knockout mice. We observed attenuated 4EBP phosphorylation in the skeletal muscle, but not in the liver, of the PGC-1α knockout mice. These data suggest that skeletal muscle-PGC-1α is important for leucine-mediated mTOR activation and protein biosynthesis.

  17. Separation by high-performance liquid chromatography of (3R)- and (3S)-beta-leucine as diastereomeric derivatives.

    PubMed

    Aberhart, D J; Cotting, J A; Lin, H J

    1985-11-15

    For studies on the coenzyme B12-dependent enzyme, leucine-2,3-aminomutase, (3R)- and (3S)-beta-leucines were synthesized. The 10-camphorsulfonamide p-nitrobenzyl esters could be resolved by normal-phase HPLC. A much better separation was obtained by reversed-phase HPLC of the diastereomeric derivatives obtained by treatment of -leucine with Marfey's reagent (N2-(5-fluoro-2,4-dinitrophenyl)-L-alaninamide).

  18. The response of weaned piglets to dietary valine and leucine.

    PubMed

    Meyer, F; Jansen van Rensburg, C; Gous, R M

    2017-01-12

    Valine (Val) is considered to be the fifth-limiting amino acid in a maize-soyabean meal diet for pigs. Excess leucine (Leu) levels often occur in commercial diets, which may attenuate the effect of Val deficiency because of an increased oxidation of Val. The objective of the present experiment was to determine the effect of increasing concentrations of Leu on the response of young piglets to dietary Val. In all, 75 Large White×Landrace entire male pigs, 44 days of age and with a mean starting weight of 13.5 kg, were used. Three of these were sacrificed at the start to determine their mean initial chemical composition. A summit feed first limiting in Val was serially diluted with a non-protein diluent to produce a series of five digestible Val concentrations of 11.9, 10.1, 8.3, 6.6 and 4.8 g/kg, with a sixth treatment being added to test that the feeds were limiting in Val. Three identical Val series, each with six levels of Val, were supplemented with increasing amounts of Leu (23, 45 and 67 g/kg), thus 18 treatments in total. All pigs were killed at the end of the trial after 18 days for analysis of water, protein, lipid and ash in the carcass. The levels of Val and Leu and their interaction significantly influenced all the measurements taken in the trial. Daily gain in liveweight, water and protein, and feed conversion efficiency all increased with dietary Val content, whereas feed intake decreased as both Val and Leu contents increased. The deleterious effect of increased Leu on feed intake and growth was more marked at lower levels of Val. Supplementing the feed with the lowest Val content with additional Val largely overcame the effect of excess Leu. The efficiency of utilisation of Val for protein growth was unaffected by the level of Leu in the feed, the primary response to excess Leu being a reduction in feed intake. An intake of around 9 g Val/day yielded maximal protein growth during the period from 44 to 62 days of age in pigs of the genotype used in

  19. Leucine signaling in the pathogenesis of type 2 diabetes and obesity

    PubMed Central

    Melnik, Bodo C

    2012-01-01

    Epidemiological evidence points to increased dairy and meat consumption, staples of the Western diet, as major risk factors for the development of type 2 diabetes (T2D). This paper presents a new concept and comprehensive review of leucine-mediated cell signaling explaining the pathogenesis of T2D and obesity by leucine-induced over-stimulation of mammalian target of rapamycin complex 1 (mTORC1). mTORC1, a pivotal nutrient-sensitive kinase, promotes growth and cell proliferation in response to glucose, energy, growth factors and amino acids. Dairy proteins and meat stimulate insulin/insulin-like growth factor 1 signaling and provide high amounts of leucine, a primary and independent stimulator for mTORC1 activation. The downstream target of mTORC1, the kinase S6K1, induces insulin resistance by phosphorylation of insulin receptor substrate-1, thereby increasing the metabolic burden of β-cells. Moreover, leucine-mediated mTORC1-S6K1-signaling plays an important role in adipogenesis, thus increasing the risk of obesity-mediated insulin resistance. High consumption of leucine-rich proteins explains exaggerated mTORC1-dependent insulin secretion, increased β-cell growth and β-cell proliferation promoting an early onset of replicative β-cell senescence with subsequent β-cell apoptosis. Disturbances of β-cell mass regulation with increased β-cell proliferation and apoptosis as well as insulin resistance are hallmarks of T2D, which are all associated with hyperactivation of mTORC1. In contrast, the anti-diabetic drug metformin antagonizes leucine-mediated mTORC1 signaling. Plant-derived polyphenols and flavonoids are identified as natural inhibitors of mTORC1 and exert anti-diabetic and anti-obesity effects. Furthermore, bariatric surgery in obesity reduces increased plasma levels of leucine and other branched-chain amino acids. Attenuation of leucine-mediated mTORC1 signaling by defining appropriate upper limits of the daily intake of leucine-rich animal and dairy

  20. Leucine Differentially Regulates Gene-Specific Translation in Mouse Skeletal Muscle.

    PubMed

    Drummond, Micah J; Reidy, Paul T; Baird, Lisa M; Dalley, Brian K; Howard, Michael T

    2017-09-01

    Background: Amino acids, especially leucine, are particularly effective in promoting protein synthesis. Leucine is known to increase the rate of protein synthesis in skeletal muscle through the mechanistic target of rapamycin complex 1-dependent, as well as -independent, signaling pathways. However, the overall translation program is poorly defined, and it is unknown how the activation of these pathways differentially controls the translation of specific mRNAs.Objective: Ribosome profiling and RNA sequencing were used to precisely define the translational program activated by an acute oral dose of leucine.Methods: Adult male C57BL/6 mice were deprived of food overnight before the delivery of an acute dose of l-leucine (9.4 mg) (n = 6) or vehicle (n = 5) and tissues collected 30 min later. Ribosome footprints and total RNA were isolated and subjected to deep sequencing. Changes in gene-specific mRNA abundance and ribosome occupancy were determined between the leucine-treated and control groups by aligning sequence reads to Reference Sequence database mRNAs and applying statistical features of the Bioconductor package edgeR.Results: Our data revealed mRNA features that confer translational control of skeletal muscle mRNAs in response to an acute dose of leucine. The subset of skeletal muscle mRNAs that are activated consists largely of terminal oligopyrimidine mRNAs (false discovery rate: <0.05), whereas those with reduced translation had 5' untranslated regions with increased length. Only the small nuclear RNAs, which are required for ribosome biogenesis, were significantly altered in RNA abundance. The inferred functional translational program activated by dietary leucine includes increased protein synthesis capacity and energy metabolism, upregulation of sarcomere-binding proteins, modulation of circadian rhythm, and suppression of select immune components.Conclusions: These results clarify the translation program acutely stimulated by leucine in mouse skeletal

  1. Protective effects of leucine against lipopolysaccharide-induced inflammatory response in Labeo rohita fingerlings.

    PubMed

    Giri, Sib Sankar; Sen, Shib Sankar; Jun, Jin Woo; Sukumaran, Venkatachalam; Park, Se Chang

    2016-05-01

    The present study investigated the protective effects of leucine against lipopolysaccharide (LPS)-induced inflammatory responses in Labeo rohita (rohu) in vivo and in vitro. Primary hepatocytes, isolated from the hepatopancreas, were exposed to different concentrations of LPS for 24 h to induce an inflammatory response, and the protective effects of leucine against LPS-induced inflammation were studied. Finally, we investigated the efficiency of dietary leucine supplementation in attenuating an immune challenge induced by LPS in vivo. Exposure of cells to 10-25 μg mL(-1) of LPS for 24 h resulted in a significant production of nitric oxide and release of lactate dehydrogenase to the medium, whereas cell viability and protein content were reduced (p < 0.05). LPS exposure (10 μg mL(-1)) increased mRNA levels of the pro-inflammatory cytokines TNF-α, IL-1β and IL-8 in vitro (p < 0.05). However, pretreatment with leucine prevented the LPS-induced upregulation of TNF-α, IL-1β and IL-8 mRNAs by downregulating TLR4, MyD88, NF-κBp65, and MAPKp38 mRNA expression. Interestingly, mRNA expression of the anti-inflammatory cytokine, IL-10, which was increased by LPS treatment, was further enhanced (p < 0.05) by leucine pretreatment. The enhanced expression of IL-10 might inhibit the production of other pro-inflammatory cytokines. It was found that leucine pretreatment attenuated the excessive activation of LPS-induced TLR4-MyD88 signaling as manifested by lower level of TLR4, MyD88, MAPKp38, NF-κBp65 and increased level of IκB-α protein in leucine pre-treatment group. In vivo experiments demonstrated that leucine pre-supplementation could protect fish against LPS-induced inflammation through an attenuation of TLR4-MyD88 signaling pathway. Taken together, we propose that leucine pre-supplementation decreases LPS-induced immune damage in rohu by enhancing the expression of IL-10 and by regulating the TLR4-MyD88 signaling pathways.

  2. Dietary leucine supplementation alters energy metabolism and induces slow-to-fast transitions in longissimus dorsi muscle of weanling piglets.

    PubMed

    Fan, Qiwen; Long, Baisheng; Yan, Guokai; Wang, Zhichang; Shi, Min; Bao, Xiaoyu; Hu, Jun; Li, Xiuzhi; Chen, Changqing; Zheng, Zilong; Yan, Xianghua

    2017-05-01

    Leucine plays an important role in promoting muscle protein synthesis and muscle remodelling. However, what percentage of leucine is appropriate in creep feed and what proteome profile alterations are caused by dietary leucine in the skeletal muscle of piglets remain elusive. In this case, we applied isobaric tags for relative and absolute quantitation to analyse the proteome profile of the longissimus dorsi muscles of weanling piglets fed a normal leucine diet (NL; 1·66 % leucine) and a high-leucine diet (HL; 2·1 % leucine). We identified 157 differentially expressed proteins between these two groups. Bioinformatics analysis of these proteins exhibited the suppression of oxidative phosphorylation and fatty acid β-oxidation, as well as the activation of glycolysis, in the HL group. For further confirmation, we identified that SDHB, ATP5F1, ACADM and HADHB were significantly down-regulated (P<0·01, except ATP5F1, P<0·05), whereas the glycolytic enzyme pyruvate kinase was significantly up-regulated (P<0·05) in the HL group. We also show that enhanced muscle protein synthesis and the transition from slow-to-fast fibres are altered by leucine. Together, these results indicate that leucine may alter energy metabolism and promote slow-to-fast transitions in the skeletal muscle of weanling piglets.

  3. Incorporation of radiolabeled leucine into protein to estimate bacterial production in plant litter, sediment, epiphytic biofilms, and water samples.

    PubMed

    Buesing, N; Gessner, M O

    2003-03-01

    The present study assessed the application of tritiated leucine incorporation into protein, as a measure of bacterial biomass production, within four benthic habitats of a littoral freshwater wetland dominated by emergent vegetation. Basic assumptions underlying the method, such as linearity of leucine incorporation, saturation level of incorporation rates, and specificity of incorporation for bacterial assemblages, were tested, and two procedures for extracting radiolabeled protein were compared. TCA precipitation followed by ultrasonication, and subsequent alkaline dissolution in 0.5 M NaOH, 25 mM EDTA, and 0.1% w/v SDS, gave best results in terms of both extraction efficiency and signal-to-noise ratio. Incorporation of leucine was linear for all habitats for up to 1 h. Saturation concentrations of leucine incorporation into protein were 150 nM for littoral surface waters, >960 nM for biofilms on plant surfaces, and 50 mM for aerobic sediment and submerged plant litter. An experiment with prokaryotic and eukaryotic inhibitors designed to examine specificity of leucine incorporation into bacterial protein showed no significant leucine incorporation into eukaryotes during short-term incubations. Calculations based on kinetic parameters of fungal leucine uptake suggest, nevertheless, that significant leucine incorporation cannot be ruled out in all situations. Thus, the leucine methodology can be used for estimating bacterial production in benthic aquatic habitats, provided that substrate saturation and isotope dilution are determined and that the active biomass of eukaryotes, such as fungi, does not greatly exceed bacterial biomass.

  4. Reviewing the Effects of l-Leucine Supplementation in the Regulation of Food Intake, Energy Balance, and Glucose Homeostasis

    PubMed Central

    Pedroso, João A.B.; Zampieri, Thais T.; Donato, Jose

    2015-01-01

    Leucine is a well-known activator of the mammalian target of rapamycin (mTOR). Because mTOR signaling regulates several aspects of metabolism, the potential of leucine as a dietary supplement for treating obesity and diabetes mellitus has been investigated. The objective of the present review was to summarize and discuss the available evidence regarding the mechanisms and the effects of leucine supplementation on the regulation of food intake, energy balance, and glucose homeostasis. Based on the available evidence, we conclude that although central leucine injection decreases food intake, this effect is not well reproduced when leucine is provided as a dietary supplement. Consequently, no robust evidence indicates that oral leucine supplementation significantly affects food intake, although several studies have shown that leucine supplementation may help to decrease body adiposity in specific conditions. However, more studies are necessary to assess the effects of leucine supplementation in already-obese subjects. Finally, although several studies have found that leucine supplementation improves glucose homeostasis, the underlying mechanisms involved in these potential beneficial effects remain unknown and may be partially dependent on weight loss. PMID:26007339

  5. Leucine Deprivation Stimulates Fat Loss via Increasing CRH Expression in the Hypothalamus and Activating The Sympathetic Nervous System

    PubMed Central

    Cheng, Ying; Zhang, Qian; Meng, Qingshu; Xia, Tingting; Huang, Zhiying; Wang, Chunxia; Liu, Bin; Chen, Shanghai; Xiao, Fei; Du, Ying

    2011-01-01

    We previously showed that leucine deprivation decreases abdominal fat mass largely by increasing energy expenditure, as demonstrated by increased lipolysis in white adipose tissue (WAT) and uncoupling protein 1 (UCP1) expression in brown adipose tissue (BAT). The goal of the present study was to investigate the possible involvement of central nervous system (CNS) in this regulation and elucidate underlying molecular mechanisms. For this purpose, levels of genes and proteins related to lipolysis in WAT and UCP1 expression in BAT were analyzed in wild-type mice after intracerebroventricular administration of leucine or corticotrophin-releasing hormone antibodies, or in mice deleted for three β-adrenergic receptors, after being maintained on a leucine-deficient diet for 7 d. Here, we show that intracerebroventricular administration of leucine significantly attenuates abdominal fat loss and blocks activation of hormone sensitive lipase in WAT and induction of UCP1 in BAT in leucine-deprived mice. Furthermore, we provide evidence that leucine deprivation stimulates fat loss by increasing expression of corticotrophin-releasing hormone in the hypothalamus via activation of stimulatory G protein/cAMP/protein kinase A/cAMP response element-binding protein pathway. Finally, we show that the effect of leucine deprivation on fat loss is mediated by activation of the sympathetic nervous system. These results suggest that CNS plays an important role in regulating fat loss under leucine deprivation and thereby provide novel and important insights concerning the importance of CNS leucine in the regulation of energy homeostasis. PMID:21719534

  6. Reviewing the Effects of L-Leucine Supplementation in the Regulation of Food Intake, Energy Balance, and Glucose Homeostasis.

    PubMed

    Pedroso, João A B; Zampieri, Thais T; Donato, Jose

    2015-05-22

    Leucine is a well-known activator of the mammalian target of rapamycin (mTOR). Because mTOR signaling regulates several aspects of metabolism, the potential of leucine as a dietary supplement for treating obesity and diabetes mellitus has been investigated. The objective of the present review was to summarize and discuss the available evidence regarding the mechanisms and the effects of leucine supplementation on the regulation of food intake, energy balance, and glucose homeostasis. Based on the available evidence, we conclude that although central leucine injection decreases food intake, this effect is not well reproduced when leucine is provided as a dietary supplement. Consequently, no robust evidence indicates that oral leucine supplementation significantly affects food intake, although several studies have shown that leucine supplementation may help to decrease body adiposity in specific conditions. However, more studies are necessary to assess the effects of leucine supplementation in already-obese subjects. Finally, although several studies have found that leucine supplementation improves glucose homeostasis, the underlying mechanisms involved in these potential beneficial effects remain unknown and may be partially dependent on weight loss.

  7. Cj1199 Affect the Development of Erythromycin Resistance in Campylobacter jejuni through Regulation of Leucine Biosynthesis

    PubMed Central

    Hao, Haihong; Li, Fei; Han, Jing; Foley, Steven L.; Dai, Menghong; Wang, Xu; Wang, Yulian; Huang, Lingli; Sun, Yawei; Liu, Zhenli; Yuan, Zonghui

    2017-01-01

    The aim of this study was to reveal the biological function of Cj1199 which was overexpressed in the laboratory induced erythromycin resistant strains. The Cj1199 deletion mutant (ΦCj1199) was constructed via insertional inactivation from its parent strain Campylobacter jejuni NCTC11168. The ΦCj1199 and NCTC11168 were then subjected to microarray and real-time PCR to find gene pathway of Cj1199. The antimicrobial susceptibility, antimicrobial resistance development, growth characteristics and leucine metabolism were examined to confirm the biological function of Cj1199. Our result showed that a total of 20 genes were down-regulated in ΦCj1199. These genes were mainly involved in leucine biosynthesis, amino acid transport and periplasmic/membrane structure. Compared to NCTC11168, ΦCj1199 was difficult to acquire higher-level erythromycin resistance during the in vitro step-wise selection. The competition growth and leucine-dependent growth assays demonstrated that ΦCj1199 imposed a growth disadvantage under pressure of erythromycin and in the leucine-free medium. In conclusion, Cj1199 gene may directly regulate the leucine biosynthesis and transport and indirectly affect the development of erythromycin resistance in C. jejuni. PMID:28144238

  8. Arabinose-Leucine Deletion Mutants of Escherichia coli B/r

    PubMed Central

    Kessler, Donald P.; Englesberg, Ellis

    1969-01-01

    The control of ara gene expression was studied in mutants of Escherichia coli B/r containing deletions which fused the l-arabinose gene complex with the leucine operon (the normal gene order being araDABIOC...leuDCBAO). Complementation experiments with stable merodiploids showed that expression of ara genes cis to araC-leu deletions was controlled by the trans-acting product of the araC gene. Expression of ara genes cis to araB-leu deletions was under leucine control. These studies confirm the existence of a region between genes araC and araB essential for normal activator controlled expression of the ara structural genes. One deletion was characterized as an araO-leu deletion. Its effect on ara gene expression was unique in that ara genes were susceptible to potential regulation by both l-arabinose and leucine. These experiments suggest that two different species of messenger ribonucleic acid (mRNA) may be produced for the ara-leu region as a result of this deletion. One, under l-arabinose-activator control, is initiated in the l-arabinose region; the other, under leucine control, is initiated in the leucine region. The latter indicates that araI can be transcribed. Whether araI is transcribed in the former instance (mRNA made under activator control) remains to be established. PMID:4892369

  9. Functional profiling discovers the dieldrin organochlorinated pesticide affects leucine availability in yeast.

    PubMed

    Gaytán, Brandon D; Loguinov, Alex V; Lantz, Stephen R; Lerot, Jan-Michael; Denslow, Nancy D; Vulpe, Chris D

    2013-04-01

    Exposure to organochlorinated pesticides such as dieldrin has been linked to Parkinson's and Alzheimer's diseases, endocrine disruption, and cancer, but the cellular and molecular mechanisms of toxicity behind these effects remain largely unknown. Here we demonstrate, using a functional genomics approach in the model eukaryote Saccharomyces cerevisiae, that dieldrin alters leucine availability. This model is supported by multiple lines of congruent evidence: (1) mutants defective in amino acid signaling or transport are sensitive to dieldrin, which is reversed by the addition of exogenous leucine; (2) dieldrin sensitivity of wild-type or mutant strains is dependent upon leucine concentration in the media; (3) overexpression of proteins that increase intracellular leucine confer resistance to dieldrin; (4) leucine uptake is inhibited in the presence of dieldrin; and (5) dieldrin induces the amino acid starvation response. Additionally, we demonstrate that appropriate negative regulation of the Ras/protein kinase A pathway, along with an intact pyruvate dehydrogenase complex, is required for dieldrin tolerance. Many yeast genes described in this study have human orthologs that may modulate dieldrin toxicity in humans.

  10. Functional Profiling Discovers the Dieldrin Organochlorinated Pesticide Affects Leucine Availability in Yeast

    PubMed Central

    Vulpe, Chris D.

    2013-01-01

    Exposure to organochlorinated pesticides such as dieldrin has been linked to Parkinson’s and Alzheimer’s diseases, endocrine disruption, and cancer, but the cellular and molecular mechanisms of toxicity behind these effects remain largely unknown. Here we demonstrate, using a functional genomics approach in the model eukaryote Saccharomyces cerevisiae, that dieldrin alters leucine availability. This model is supported by multiple lines of congruent evidence: (1) mutants defective in amino acid signaling or transport are sensitive to dieldrin, which is reversed by the addition of exogenous leucine; (2) dieldrin sensitivity of wild-type or mutant strains is dependent upon leucine concentration in the media; (3) overexpression of proteins that increase intracellular leucine confer resistance to dieldrin; (4) leucine uptake is inhibited in the presence of dieldrin; and (5) dieldrin induces the amino acid starvation response. Additionally, we demonstrate that appropriate negative regulation of the Ras/protein kinase A pathway, along with an intact pyruvate dehydrogenase complex, is required for dieldrin tolerance. Many yeast genes described in this study have human orthologs that may modulate dieldrin toxicity in humans. PMID:23358190

  11. IGFBP-1 hyperphosphorylation in response to leucine deprivation is mediated by the AAR pathway.

    PubMed

    Malkani, Niyati; Jansson, Thomas; Gupta, Madhulika B

    2015-09-05

    Insulin-like growth factor-1 (IGF-I) is the key regulator of fetal growth. IGF-I bioavailability is markedly diminished by IGF binding protein-1 (IGFBP-1) phosphorylation. Leucine deprivation strongly induces IGFBP-1 hyperphosphorylation, and plays an important role in fetal growth restriction (FGR). FGR is characterized by decreased amino acid availability, which activates the amino acid response (AAR) and inhibits the mechanistic target of rapamycin (mTOR) pathway. We investigated the role of AAR and mTOR in mediating IGFBP-1 secretion and phosphorylation in HepG2 cells in leucine deprivation. mTOR inhibition (rapamycin or raptor + rictor siRNA), or activation (DEPTOR siRNA) demonstrated a role of mTOR in leucine deprivation-induced IGFBP-1 secretion but not phosphorylation. When the AAR was blocked (U0126, or ERK/GCN2 siRNA), both IGFBP-1 secretion and hyperphosphorylation (pSer101/pSer119/pSer169) due to leucine deprivation were prevented. CK2 inhibition by TBB also attenuated IGFBP-1 phosphorylation in leucine deprivation. These results suggest that the AAR and mTOR independently regulate IGFBP-1 secretion and phosphorylation in response to decreased amino acid availability.

  12. Fatty acid and cholesterol synthesis from specifically labeled leucine by isolated rat hepatocytes.

    PubMed

    Mathias, M M; Sullivan, A C; Hamilton, J G

    1981-10-01

    Hepatocytes isolated from female rats meal-fed a high-glucose diet were incubated in Krebs-Henseleit bicarbonate medium containing 16.5 mM glucose, 3H2O, and 14C-labeled amino acids (-)-Hydroxycitrate depressed the incorporation of 3H2O and [14C] alanine into fatty acids and cholesterol. Incorporation of [U-14C]leucine into lipids was not affected but incorporation of 3H2O into lipids was decreased significantly by (-)-hydroxycitrate. (-)-Hydroxycitrate depressed the incorporation of radioactivity from [2-14C]leucine into fatty acids and cholesterol by 61 and 38%, respectively, and stimulated the incorporation of radioactivity from [4,5-3H]leucine 35 and 28%. As [2-14C]leucine labels the acetyl-CoA pool and [4,5-3H]leucine labels the acetoacetate pool, it was concluded that mitochondrial 3-hydroxy-3-methylglutaryl-CoA is not incorporated intact into cholesterol, and that acetoacetate can be activated effectively in the liver cytosol for support of cholesterol and fatty acid synthesis.

  13. Renoprotective effects of Maillard reaction products generated during heat treatment of ginsenoside Re with leucine.

    PubMed

    Kim, Ji Hoon; Han, Im-Ho; Yamabe, Noriko; Kim, Young-Joo; Lee, Woojung; Eom, Dae-Woon; Choi, Pilju; Cheon, Gab Jin; Jang, Hyuk-Jai; Kim, Su-Nam; Ham, Jungyeob; Kang, Ki Sung

    2014-01-15

    The structural change of ginsenoside and the generation of Maillard reaction products (MRPs) are important to the increase in the biological activities of Panax ginseng. This study was carried out to identify the renoprotective active component of P. ginseng using the Maillard reaction model experiment with ginsenoside Re and leucine. Ginsenoside Re was gradually converted into less-polar ginsenosides Rg2, Rg6 and F4 by heat-processing, followed by separation of the glucosyl moiety at carbon-20. The free radical-scavenging activity of the ginsenoside Re-leucine mixture was increased by heat-processing. The improved free radical-scavenging activity by heat-processing was mediated by the generation of MRPs from the reaction of glucose and leucine. The cisplatin-induced LLC-PK1 renal cell damage was also significantly reduced by treatment with MRPs. Moreover, the heat-processed glucose-leucine mixture (major MRPs from the ginsenoside Re-leucine mixture) showed protective effects against cisplatin-induced oxidative renal damage in rats through the inhibition of caspase-3 activation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Substrate binding and formation of an occluded state in the leucine transporter.

    PubMed

    Celik, Leyla; Schiøtt, Birgit; Tajkhorshid, Emad

    2008-03-01

    Translocation through the extracellular vestibule and binding of leucine in the leucine transporter (LeuT) have been studied with molecular dynamics simulations. More than 0.1 mus of all-atom molecular dynamics simulations have been performed on different combinations of LeuT, bound substrate, and bound structural Na(+) ions to describe molecular events involved in substrate binding and in the formation of the occluded state and to investigate the dynamics of this state. Three structural features are found to be directly involved in the initial steps of leucine transport: a Na(+) ion directly coordinated to leucine (Na-1), two aromatic residues closing the binding site toward the extracellular vestibule (Tyr-108 and Phe-253), and a salt bridge in the extracellular vestibule (Arg-30 and Asp-404). These features account for observed differences between simulations of LeuT with and without bound substrate and for a possible pathway for leucine binding and thereby formation of the occluded LeuT binding site.

  15. Asymmetric photolysis of /RS/-leucine with circularly polarized ultraviolet light

    NASA Technical Reports Server (NTRS)

    Flores, J. J.; Bonner, W. A.; Massey, G. A.

    1977-01-01

    (RS)-leucine in 0.1 M HCl solution has been subjected to photolysis with 212.8-nm right (R-) and left circularly polarized light (LCPL) obtained from a laser source. RCPL preferentially photolyzed the (R)-leucine component and LCPL the (S)-leucine component of the RS substrate. The enantiomeric excess produced were 1.98% for the 59% conversion with RCPL and 2.50% for the 75% conversion with LCPL. These 'equal and opposite' effects represent the second highest enantiomeric enrichments yet reported for an asymmetric photolysis and the first ever reported for a prebiotically important substrate - an amino acid. Implications regarding the origin of optical activity are briefly discussed.

  16. X-ray scattering indicates that the leucine zipper is a coiled coil

    SciTech Connect

    Rasmussen, R.; Benvegnu, D. ); O'Shea, E.K.; Kim, P.S. Massachusetts Inst. of Tech., Cambridge ); Alber, T. Univ. of Utah, Salt Lake City )

    1991-01-15

    Dimerization of the bZIP class of eukaryotic transcriptional control proteins requires a sequence motif called the leucine zipper. The authors have grown two distinct crystal forms of a 33-amino acid peptide corresponding to the leucine zipper of the yeast transcriptional activator GCN4. This peptide is known to form a dimer of parallel helices in solution. X-ray scattering from both crystal forms shows reflections that are diagnostic of coiled coils. The most notable reflections occur at {approximately}5.2{angstrom} resolution and correspond to the pitch of helices in coiled coils. There is no diffraction maximum near 5.4{angstrom}, the characteristic pitch of straight helices. The results provide direct evidence that the leucine zipper of GCN4 is a coiled coil.

  17. Leucine aminopeptidase: an inducible component of the defense response in Lycopersicon esculentum (tomato).

    PubMed

    Pautot, V; Holzer, F M; Reisch, B; Walling, L L

    1993-11-01

    A leucine aminopeptidase (EC 3.4.11.1) cDNA clone (DR57) that was induced in response to Pseudomonas syringae pv. tomato (P.s. tomato) infection was isolated using a subtractive hybridization-enriched cDNA probe. Genomic DNA blot analysis showed that the tomato genome had two leucine aminopeptidase genes. The levels of DR57 mRNAs after P.s. tomato infection and mechanical wounding were determined in two inbred tomato lines that exhibit susceptibility and resistance to P.s. tomato. DR57 mRNAs were detected 12 hours after infection and 4 hours after wounding. Furthermore, DR57 mRNAs were systemically induced in response to wounding. DR57 mRNAs were induced in leaves after Spodoptera littoralis feeding but were not detected in detached leaf controls. Possible roles for the DR57 leucine aminopeptidase in the defense reactions are discussed.

  18. Morphological templating of metastable calcium carbonates by the amino acid leucine

    NASA Astrophysics Data System (ADS)

    Thompson, S. P.; Parker, J. E.; Street, S. R.; Tang, C. C.

    2011-03-01

    The in vitro precipitation of the metastable CaCO3 phases aragonite and vaterite in the presence of leucine is investigated. Under normal conditions, the production of CaCO3 via the hydrolysis of urea method favours the formation of regular needle-like aragonite crystals, with very minor quantities of vaterite and calcite. However in the presence of leucine, aragonite forms highly branched structures and the vaterite yield is increased, forming flower-like clusters composed of nano-thin sheets. Both the degree of aragonite branching and the occurrence, regularity of shape and number of vaterite "petals" increases with leucine concentration. The two phases exhibit different variations in their crystallographic parameters with increasing concentration, while the molecular structure appears unaffected.

  19. TGFβ1-induced leucine limitation uncovered by differential ribosome codon reading.

    PubMed

    Loayza-Puch, Fabricio; Rooijers, Koos; Zijlstra, Jelle; Moumbeini, Behzad; Zaal, Esther A; Oude Vrielink, Joachim F; Lopes, Rui; Pineiro Ugalde, Alejandro; Berkers, Celia R; Agami, Reuven

    2017-03-08

    Cancer cells modulate their metabolic networks to support cell proliferation and a higher demand of building blocks. These changes may restrict the availability of certain amino acids for protein synthesis, which can be utilized for cancer therapy. However, little is known about the amino acid demand changes occurring during aggressive and invasive stages of cancer. Recently, we developed diricore, an approach based on ribosome profiling that can uncover amino acid limitations. Here, we applied diricore to a cellular model in which epithelial breast cells respond rapidly to TGFβ1, a cytokine essential for cancer progression and metastasis, and uncovered shortage of leucine. Further analyses indicated that TGFβ1 treatment of human breast epithelial cells reduces the expression of SLC3A2, a subunit of the leucine transporter, which diminishes leucine uptake and inhibits cell proliferation. Thus, we identified a specific amino acid limitation associated with the TGFβ1 response, a vulnerability that might be associated with aggressiveness in cancer.

  20. Incorporation of fucose and leucine into PNS myelin proteins in nerves undergoing early Wallerian degeneration

    SciTech Connect

    Peterson, R.G.; Baughman, S.; Scheidler, D.M.

    1981-02-01

    The simultaneous incorporation of (/sup 3/H)fucose and (1-/sup 14/C)leucine into normal rat sciatic nerve was examined using an in vitro incubation model. A linear rate of protein precursor uptake was found in purified myelin protein over 1/2-6 hr of incubation utilizing a supplemented medium containing amino acids. This model was then used to examine myelin protein synthesis in nerves undergoing degeneration at 1-4 days following a crush injury. Data showed a statistically significant decrease in the ratio of fucose to leucine at 2, 3, and 4 days of degeneration, which was the consequence of a significant increase in leucine uptake. These results, plus substantial protein recovery in axotomized nerves, are indicative of active synthesis of proteins that purify with myelin during early Wallerian degeneration.

  1. The distribution of [14C] leucine and 85Sr labeled microspheres from rat incisor root canals.

    PubMed

    Feiglin, B; Reade, P C

    1979-03-01

    The distribution of [14C] leucine and 85Sr labeled tracer microspheres from rat incisor pulp canals was investigated in an effort to establish the potential for passage of substances from within the root canal to the systemic circulation. Following introduction of the tracer materials into the pulp canals, the radioactivity in the lungs, spleen, kidney, liver, heart, blood, skeletal muscle, adrenal glands, salivary glands, and submandibular lymph nodes was determined. At all of the time intervals studied the incorporation of [14C] leucine into the adrenal gland was significantly greater than the [14C] leucine incorporation into the other organs. High levels of 85Sr labeled microspheres were detected in the ipsilateral submandibular glands and submandibular lymph nodes and in the lungs.

  2. Asymmetric photolysis of /RS/-leucine with circularly polarized ultraviolet light

    NASA Technical Reports Server (NTRS)

    Flores, J. J.; Bonner, W. A.; Massey, G. A.

    1977-01-01

    (RS)-leucine in 0.1 M HCl solution has been subjected to photolysis with 212.8-nm right (R-) and left circularly polarized light (LCPL) obtained from a laser source. RCPL preferentially photolyzed the (R)-leucine component and LCPL the (S)-leucine component of the RS substrate. The enantiomeric excess produced were 1.98% for the 59% conversion with RCPL and 2.50% for the 75% conversion with LCPL. These 'equal and opposite' effects represent the second highest enantiomeric enrichments yet reported for an asymmetric photolysis and the first ever reported for a prebiotically important substrate - an amino acid. Implications regarding the origin of optical activity are briefly discussed.

  3. The effect of a high protein diet on leucine and alanine turnover in acid maltase deficiency.

    PubMed Central

    Umpleby, A M; Trend, P S; Chubb, D; Conaglen, J V; Williams, C D; Hesp, R; Scobie, I N; Wiles, C M; Spencer, G; Sönksen, P H

    1989-01-01

    Leucine and alanine production rate was measured in 5 patients with acid maltase deficiency in the postabsorptive state, following 6 months on a normal diet with placebo and 6 months on an isocaloric high protein diet (16-22% protein). Whole body leucine production rate, a measure of protein degradation, expressed in terms of lean body mass was significantly greater than in five control subjects. Following the high protein diet, leucine production rate was decreased in four of the five patients but this was not statistically significant. Alanine production rate expressed in terms of lean body mass was significantly greater than in control subjects. After the high protein diet, alanine production rate and concentration were significantly decreased (p less than 0.05). There were no significant improvements in any of the clinically relevant variables measured in these patients. It is possible that a larger increase in protein intake over a longer time period may have a clinical effect. PMID:2507747

  4. [A new water-soluble lubricant of tablets-L-leucine combined with PEG6000].

    PubMed

    Liu, Wei; Huang, Kai; Rao, Xiaoyong; Liu, Xiaoyan; Sun, Shasha; Luo, Xiaojian

    2011-08-01

    To prepare an effective and water-soluble lubricant. Co-sprayed lubricant (L-leucine and polyethylene glycol 6000 co-sprayed according to a certain proportion) and mixed lubricant (the physical mixture of spayed L-leucine and crushed polyethylene glycol 6000) were prepared and polyethylene glycol 6000, L-leucine, magnesium stearate, sodium stearyl fumarate and sodium chloride are crushed and sieved, respectively. Residual force, appearance of solution and disintegration time were considered as response variables of the lubrication effect to evaluate different lubricants. The changes of the co-sprayed lubricant were studied by differential scanning calorimetry, fourier infrared, electronic scanning microscope and X-ray diffraction. The efficacy of co-sprayed lubricant is better than other lubricants. Efficacy is improved by external form change without inner components and crystal changes. Co-sprayed lubricant is a good water soluble tablet lubricant which has good efficacy.

  5. Hypothalamic-Pituitary Function in Diverse Hyperprolactinemic States

    PubMed Central

    Boyar, R. M.; Kapen, S.; Finkelstein, J. W.; Perlow, M.; Sassin, J. F.; Fukushima, D. K.; Weitzman, E. D.; Hellman, Leon

    1974-01-01

    Prolactin secretion in normal adults is characterized by periods of episodic secretion which increase in magnitude during sleep. In this study, we report the 24-h mean prolactin concentrations, prolactin secretory patterns, and associated pituitary hormone function in nine patients (seven women and two men) with hyperprolactinemia of diverse etiologies. Four of the women and one of the men had clinically demonstrable pituitary tumors, one boy had a hypothalamic tumor, and the three other women had “functional” hyperprolactinemia. The 24-h mean prolactin concentrations derived from averaging the 20-min interval samples for 24 h ranged from 28.6 to 1,220 ng/ml. The plasma prolactin patterns in these patients showed persistence of episodic secretion in all and loss of the normal sleep-wake difference in plasma prolactin in seven of nine. Three of the patients with galactorrhea and comparable 24-h mean prolactin concentrations (58.3, 59.7, and 64.3 ng/ml) showed similar prolactin secretory patterns despite different etiologic mechanisms. Evaluation of the secretory patterns of luteinizing hormone (LH) in these patients showed loss of normal pulsatile LH release and a low 24-h mean LH concentration in the patient with the pituitary tumor, while the two patients without clinically demonstrable pituitary tumors (“post-pill” galactorrhea and “idiopathic” galactorrhea) showed normal LH secretory patterns and 24-h mean LH concentrations. The 24-h mean cortisol concentrations and secretory patterns were normal in five of the seven patients who had these parameters measured. The patient with the hypothalamic tumor had a low 24-h mean cortisol concentration and production rate and absent response to metyrapone. The patient with “idiopathic” galactorrhea had an elevated 24-h mean cortisol concentration but normal cortisol production rate and urinary 17-hydroxycorticoid excretion. Growth hormone secretion was abnormal in four of the patients (one with the

  6. Thyroid hormone activation of retinoic acid synthesis in hypothalamic tanycytes

    PubMed Central

    Stoney, Patrick N.; Helfer, Gisela; Rodrigues, Diana; Morgan, Peter J.

    2015-01-01

    Thyroid hormone (TH) is essential for adult brain function and its actions include several key roles in the hypothalamus. Although TH controls gene expression via specific TH receptors of the nuclear receptor class, surprisingly few genes have been demonstrated to be directly regulated by TH in the hypothalamus, or the adult brain as a whole. This study explored the rapid induction by TH of retinaldehyde dehydrogenase 1 (Raldh1), encoding a retinoic acid (RA)‐synthesizing enzyme, as a gene specifically expressed in hypothalamic tanycytes, cells that mediate a number of actions of TH in the hypothalamus. The resulting increase in RA may then regulate gene expression via the RA receptors, also of the nuclear receptor class. In vivo exposure of the rat to TH led to a significant and rapid increase in hypothalamic Raldh1 within 4 hours. That this may lead to an in vivo increase in RA is suggested by the later induction by TH of the RA‐responsive gene Cyp26b1. To explore the actions of RA in the hypothalamus as a potential mediator of TH control of gene regulation, an ex vivo hypothalamic rat slice culture method was developed in which the Raldh1‐expressing tanycytes were maintained. These slice cultures confirmed that TH did not act on genes regulating energy balance but could induce Raldh1. RA has the potential to upregulate expression of genes involved in growth and appetite, Ghrh and Agrp. This regulation is acutely sensitive to epigenetic changes, as has been shown for TH action in vivo. These results indicate that sequential triggering of two nuclear receptor signalling systems has the capability to mediate some of the functions of TH in the hypothalamus. GLIA 2016;64:425–439 PMID:26527258

  7. Neurological complications after gamma-knife radiosurgery for hypothalamic hamartoma.

    PubMed

    Butragueño Laiseca, Laura; Oikonomopoulou, Niki; Miranda Herrero, María Concepción; Barredo Valderrama, Estíbaliz; Vázquez López, María; Jiménez de Domingo, Ana; Aguado Del Hoyo, Alejandra; García-Leal, Roberto; Meiriño, Rosa M

    2016-09-01

    The Gamma-knife technique is a safe and effective option for the treatment of hypothalamic hamartomas that produce epileptic seizures refractory to medical treatment and/or serious behavioral disorders. After this type of radiosurgery, an adequate symptomatic control is normally achieved, with notable decrease or even disappearance of the seizures. Radiological changes, such as a decrease in the size of the tumor or adjacent edema secondary to non-necrotizing radioinduced inflammatory reaction are unusual consequences. Side effects and neurological complications are also rare events. This report describes an unusual case of complete radiological resolution of a hypothalamic hamartoma as well as neurological complications after Gamma-knife surgery (receiving 13 Gy to the 85% isodose line, 1 cm(3) of tumor volume) in a 8-year-old boy who suffered from severe refractory seizures. After radiosurgery, the patient experienced a notable improvement in his symptoms, achieving seizure cessation within 3 months. However, 4 months after the procedure he presented drowsiness, fever and decreased level of consciousness due to a direct effect on the hypothalamus with local and regional edema secondary to the radiosurgery that was performed. He was successfully treated with corticosteroids (with a total duration of 11 months), and twelve months after the surgery, complete disappearance of both the nodular lesion and the secondary edema was observed. The patient remains seizure-free in the last 16 months, with remarkable changes in his behavior. The present case shows that complete radiological resolution of a hypothalamic hamartoma after Gamma-knife technique is unusual but possible, without long-term neurological consequences. Nevertheless, despite its low incidence, if a patient presents neurological symptoms, primarily during the first year after intervention, possible complications of this type of surgery must be taken into account. Copyright © 2016 European Paediatric

  8. The hypothalamic peptidergic system, hypocretin/orexin and vigilance control.

    PubMed

    Nishino, Seiji

    2007-06-01

    Using forward and reverse genetics, the genes (hypocretin/orexin ligand and its receptor) involved in the pathogenesis of the sleep disorder, narcolepsy, in animals, have been identified. Mutations in hypocretin related-genes are extremely rare in humans, but hypocretin-ligand deficiency is found in most narcolepsy-cataplexy cases. Hypocretin deficiency in humans can be clinically detected by CSF hypocretin-1 measures, and undetectably low CSF hypocretin-1 is now included in the revised international diagnostic criteria of narcolepsy. Since hypocretin-ligand deficiency is the major pathophysiology in human narcolepsy, hypocretin replacements (using hypocretin agonists or gene therapy) are promising future therapeutic options. New insights into the roles of hypocretin system on sleep physiology have also rapidly increased. Hypocretins are involved in various fundamental hypothalamic functions such as feeding, energy homeostasis and neuroendocrine regulation. Hypocretin neurons project to most ascending arousal systems (including monoaminergic and cholinergic systems), and generally exhibit excitatory inputs. Together with the recent finding of the sleep promoting system in the hypothalamus (especially in the GABA/galanin ventrolateral preoptic area which exhibits inhibitory inputs to these ascending systems), the hypothalamus is now recognized as the most important brain site for the sleep switch, and other peptidergic systems may also participate in this regulation. Meanwhile, narcolepsy now appears to be a more complex condition than previously thought. The pathophysiology of the disease is involved in the abnormalities of sleep and various hypothalamic functions due to hypocretin deficiency, such as the changes in energy homeostasis, stress reactions and rewarding. Narcolepsy is therefore, an important model to study the link between sleep regulation and other fundamental hypothalamic functions.

  9. Hypothalamic opioid-melanocortin appetitive balance and addictive craving.

    PubMed

    Reece, Albert Stuart

    2011-01-01

    Whilst the parallels between drug and food craving are receiving increasing attention, the recently elucidated complex physiology of the hypothalamic appetite regulatory centres has been largely overlooked in the efforts to understand drug craving which is one of the most refractory and problematic aspects of drug and behavioural addictions. Important conceptual gains could be made by researchers from both appetite and addiction neuroscience if they were to have an improved understanding of each others' disciplines. It is well known in addiction medicine that the use of many substances is elevated in opiate dependency. There is voluminous evidence of very high rates of drug use in opiate agonist maintained patients, and the real possibility exists that opiate agonist therapy therefore increases drug craving. Conversely, opiate antagonist therapy with naloxone or naltrexone has been shown to reduce most chemical and behavioural addictions, and naltrexone is now being developed together with bupropion as the anti-obesity drug "Contrave". Hypothalamic melanocortins, particularly α-MSH, are known to constitute the main brake to consumptive behaviour of food. There is a well described antagonism between melanocortins and opioids at many loci including the hypothalamus. Administration of exogenous opiates is known to both suppress α-MSH and to stimulate hedonic food consumption. Opiate maintenance programs are associated with weight gain. As monoamines, opioids and cannabinoids are known to be involved in appetite regulation, and as endorphin opioids are known to be perturbed in other addictions, further exploration of the hypothalamic appetite regulatory centre would appear to be an obvious, albeit presently largely overlooked, locus in which to study drug and other craving mechanisms.

  10. Hypothalamic neuropeptide systems and anticipatory weight change in Siberian hamsters.

    PubMed

    Adam, C L; Mercer, J G

    2001-01-01

    Seasonal animals are able both to programme changes in body weight in response to annual changes in photoperiod (anticipatory regulation) and to correct changes in body weight caused by imposed energetic demand (compensatory regulation). Experimental evidence from the Siberian hamster suggests that seasonally appropriate body weight is continually reset according to photoperiodic history, even when actual body weight is driven away from this target weight by manipulation of energy intake. These characteristics constitute the "sliding set point" of seasonal body weight regulation. To define the mechanisms and molecules underlying anticipatory body weight regulation, we are investigating the involvement of hypothalamic systems with an established role in the compensatory defence of body weight. Weight loss or restricted growth induced by short days (SD) results in low circulating leptin compared with long day (LD) controls. However, this chronic low leptin signal is read differently from acute low leptin resulting from food deprivation; leptin receptor gene expression in the hypothalamic arcuate nucleus (ARC) is lower in SD, whereas food deprivation increases expression levels, suggesting changes in sensitivity to leptin feedback. SD alterations in mRNA levels for a number of hypothalamic neuropeptide and receptor genes appear counter-intuitive for a SD body weight trajectory. However, early increases in ARC cocaine-and amphetamine-regulated transcript (CART) gene expression in SDs could be involved in driving body weight loss or growth restriction. The sites of photoperiod interaction with energy balance neuronal circuitry and the neurochemical encoding of body weight set point require full characterisation. Study of anticipatory regulation in seasonal animals offers new insight into body weight regulation across mammalian species, including man.

  11. Projections from the Subfornical Region of the Lateral Hypothalamic Area

    PubMed Central

    GOTO, MARINA; CANTERAS, NEWTON S.; BURNS, GULLY; SWANSON, LARRY W.

    2010-01-01

    The L-shaped anterior zone of the lateral hypothalamic area’s subfornical region (LHAsfa) is delineated by a pontine nucleus incertus input. Function evidence suggests the subfornical region and nucleus incertus modulate foraging and defensive behaviors, although subfornical region connections are poorly understood. A high resolution Phaseolus vulgaris-leucoagglutinin (PHAL) structural analysis is presented here of the LHAsfa neuron population’s overall axonal projection pattern. The strongest LHAsfa targets are in the interbrain and cerebral hemisphere. The former include inputs to anterior hypothalamic nucleus, dorsomedial part of the ventromedial nucleus, and ventral region of the dorsal premammillary nucleus (defensive behavior control system components), and to lateral habenula and dorsal region of the dorsal premammillary nucleus (foraging behavior control system components). The latter include massive inputs to lateral and medial septal nuclei (septo-hippocampal system components), and inputs to bed nuclei of the stria terminalis posterior division related to the defensive behavior system, intercalated amygdalar nucleus (projecting to central amygdalar nucleus), and posterior part of the basomedial amygdalar nucleus. LHAsfa vertical and horizontal limb basic projection patterns are similar, although each preferentially innervates certain terminal fields. Lateral hypothalamic area regions immediately medial, lateral, and caudal to the LHAsfa each generate quite distinct projection patterns. Combined with previous evidence that major sources LHAsfa neural inputs include the parabrachial nucleus (nociceptive information), defensive and foraging behavior system components, and the septo-hippocampal system, the present results suggest that the LHAsfa helps match adaptive behavioral responses (either defensive or foraging) to current internal motivational status and external environmental conditions. PMID:16261534

  12. The I2C family from the wilt disease resistance locus I2 belongs to the nucleotide binding, leucine-rich repeat superfamily of plant resistance genes.

    PubMed Central

    Ori, N; Eshed, Y; Paran, I; Presting, G; Aviv, D; Tanksley, S; Zamir, D; Fluhr, R

    1997-01-01

    Characterization of plant resistance genes is an important step in understanding plant defense mechanisms. Fusarium oxysporum f sp lycopersici is the causal agent of a vascular wilt disease in tomato. Genes conferring resistance to plant vascular diseases have yet to be described molecularly. Members of a new multigene family, complex I2C, were isolated by map-based cloning from the I2 F. o. lycopersici race 2 resistance locus. The genes show structural similarity to the group of recently isolated resistance genes that contain a nucleotide binding motif and leucine-rich repeats. Importantly, the presence of I2C antisense transgenes abrogated race 2 but not race 1 resistance in otherwise normal plants. Expression of the complete sense I2C-1 transgene conferred significant but partial resistance to F. o. lycopersici race 2. All members of the I2C gene family have been mapped genetically and are dispersed on three different chromosomes. Some of the I2C members cosegregate with other tomato resistance loci. Comparison within the leucine-rich repeat region of I2C gene family members shows that they differ from each other mainly by insertions or deletions. PMID:9144960

  13. The leucine-responsive regulatory protein, a global regulator of metabolism in Escherichia coli.

    PubMed Central

    Calvo, J M; Matthews, R G

    1994-01-01

    The leucine-responsive regulatory protein (Lrp) regulates the expression of more than 40 genes and proteins in Escherichia coli. Among the operons that are positively regulated by Lrp are operons involved in amino acid biosynthesis (ilvIH, serA)), in the biosynthesis of pili (pap, fan, fim), and in the assimilation of ammonia (glnA, gltBD). Negatively regulated operons include operons involved in amino acid catabolism (sdaA, tdh) and peptide transport (opp) and the operon coding for Lrp itself (lrp). Detailed studies of a few members of the regulon have shown that Lrp can act directly to activate or repress transcription of target operons. A substantial fraction of operons regulated by Lrp are also regulated by leucine, and the effect of leucine on expression of these operons requires a functional Lrp protein. The patterns of regulation are surprising and interesting: in some cases activation or repression mediated by Lrp is antagonized by leucine, in other cases Lrp-mediated activation or repression is potentiated by leucine, and in still other cases leucine has no effect on Lrp-mediated regulation. Current research is just beginning to elucidate the detailed mechanisms by which Lrp can mediate such a broad spectrum of regulatory effects. Our view of the role of Lrp in metabolism may change as more members of the regulon are identified and their regulation characterized, but at this point Lrp seems to be important in regulating nitrogen metabolism and one-carbon metabolism, permitting adaptations to feast and to famine. PMID:7968922

  14. Regulation of Prolactin in Mice with Altered Hypothalamic Melanocortin Activity

    PubMed Central

    Dutia, Roxanne; Kim, Andrea J.; Mosharov, Eugene; Savontaus, Eriika; Chua, Streamson C.; Wardlaw, Sharon L.

    2012-01-01

    This study used two mouse models with genetic manipulation of the melanocortin system to investigate prolactin regulation. Mice with overexpression of the melanocortin receptor (MC-R) agonist, α-melanocyte-stimulating hormone (Tg-MSH) or deletion of the MC-R antagonist agouti-related protein (AgRP KO) were studied. Male Tg-MSH mice had lower blood prolactin levels at baseline (2.9±0.3 vs 4.7±0.7 ng/ml) and after restraint stress(68 ±6.5 vs 117±22 ng/ml) versus WT (p<0.05); however, pituitary prolactin content was not different. Blood prolactin was also decreased in male AgRP KO mice at baseline (4.2±0.5 vs 7.6±1.3 ng/ml) and after stress (60±4.5 vs 86.1±5.7 ng/ml) vs WT (p <0.001). Pituitary prolactin content was lower in male AgRP KO mice (4.3±0.3 vs 6.7±0.5 μg/pituitary, p <0.001) versus WT. No differences in blood or pituitary prolactin levels were observed in female AgRP KO mice versus WT. Hypothalamic dopamine activity was assessed as the potential mechanism responsible for changes in prolactin levels. Hypothalamic tyrosine hydroxylase mRNA was measured in both genetic models versus WT mice and hypothalamic dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) content were measured in male AgRP KO and WT mice but neither were significantly different. However, these results do not preclude changes in dopamine activity as dopamine turnover was not directly investigated. This is the first study to show that baseline and stress-induced prolactin release and pituitary prolactin content are reduced in mice with genetic alterations of the melanocortin system and suggests that changes in hypothalamic melanocortin activity may be reflected in measurements of serum prolactin levels. PMID:22800691

  15. Hypothalamic hamartoma in an unusual case with delayed puberty.

    PubMed

    Nakhaeimoghadam, Maryam; Rostami, Parastoo; Zare-Shahabadi, Ameneh; Mehdizadeh, Mehrzad; Rabbani, Ali; Rezaei, Nima

    2013-01-01

    Hypothalamic hamartoma (HH) is a rare intracranial lesion that usually presents with classic triad of central precocious puberty, gelastic epilepsy, and developmental delay. Herein, a 14-year old boy is presented in whom the diagnosis of HH was made by magnetic resonance imaging. While he did not have any complain of precocious puberty, he surprisingly suffered from delay in puberty. The definite diagnosis of HH can only be made by appropriate imaging, in a case with atypical feature of delay in puberty and in the absence of gelastic epilepsy. To our best knowledge, this is the first case of HH who is presented with delay in puberty as of first manifestation.

  16. Methamphetamine and the hypothalamic-pituitary-adrenal axis

    PubMed Central

    Zuloaga, Damian G.; Jacobskind, Jason S.; Raber, Jacob

    2015-01-01

    Psychostimulants such as methamphetamine (MA) induce significant alterations in the function of the hypothalamic-pituitary-adrenal (HPA) axis. These changes in HPA axis function are associated with altered stress-related behaviors and might contribute to addictive processes such as relapse. In this mini-review we discuss acute and chronic effects of MA (adult and developmental exposure) on the HPA axis, including effects on HPA axis associated genes/proteins, brain regions, and behaviors such as anxiety and depression. A better understanding of the mechanisms through which MA affects the HPA axis may lead to more effective treatment strategies for MA addiction. PMID:26074755

  17. Alterations in the hypothalamic melanocortin pathway in amyotrophic lateral sclerosis.

    PubMed

    Vercruysse, Pauline; Sinniger, Jérôme; El Oussini, Hajer; Scekic-Zahirovic, Jelena; Dieterlé, Stéphane; Dengler, Reinhard; Meyer, Thomas; Zierz, Stephan; Kassubek, Jan; Fischer, Wilhelm; Dreyhaupt, Jens; Grehl, Torsten; Hermann, Andreas; Grosskreutz, Julian; Witting, Anke; Van Den Bosch, Ludo; Spreux-Varoquaux, Odile; Ludolph, Albert C; Dupuis, Luc

    2016-04-01

    Amyotrophic lateral sclerosis, the most common adult-onset motor neuron disease, leads to death within 3 to 5 years after onset. Beyond progressive motor impairment, patients with amyotrophic lateral sclerosis suffer from major defects in energy metabolism, such as weight loss, which are well correlated with survival. Indeed, nutritional intervention targeting weight loss might improve survival of patients. However, the neural mechanisms underlying metabolic impairment in patients with amyotrophic lateral sclerosis remain elusive, in particular due to the lack of longitudinal studies. Here we took advantage of samples collected during the clinical trial of pioglitazone (GERP-ALS), and characterized longitudinally energy metabolism of patients with amyotrophic lateral sclerosis in response to pioglitazone, a drug with well-characterized metabolic effects. As expected, pioglitazone decreased glycaemia, decreased liver enzymes and increased circulating adiponectin in patients with amyotrophic lateral sclerosis, showing its efficacy in the periphery. However, pioglitazone did not increase body weight of patients with amyotrophic lateral sclerosis independently of bulbar involvement. As pioglitazone increases body weight through a direct inhibition of the hypothalamic melanocortin system, we studied hypothalamic neurons producing proopiomelanocortin (POMC) and the endogenous melanocortin inhibitor agouti-related peptide (AGRP), in mice expressing amyotrophic lateral sclerosis-linked mutant SOD1(G86R). We observed lower Pomc but higher Agrp mRNA levels in the hypothalamus of presymptomatic SOD1(G86R) mice. Consistently, numbers of POMC-positive neurons were decreased, whereas AGRP fibre density was elevated in the hypothalamic arcuate nucleus of SOD1(G86R) mice. Consistent with a defect in the hypothalamic melanocortin system, food intake after short term fasting was increased in SOD1(G86R) mice. Importantly, these findings were replicated in two other amyotrophic

  18. Experience salience gates endocannabinoid signaling at hypothalamic synapses.

    PubMed

    Wamsteeker Cusulin, Jaclyn I; Senst, Laura; Teskey, G Campbell; Bains, Jaideep S

    2014-04-30

    Alterations in synaptic endocannabinoid signaling are a widespread neurobiological consequence of many in vivo experiences, including stress. Here, we report that stressor salience is critical for bidirectionally modifying presynaptic CB-1 receptor (CB1R) function at hypothalamic GABA synapses controlling the neuroendocrine stress axis in male rats. While repetitive, predictable stressor exposure impairs presynaptic CB1R function, these changes are rapidly reversed upon exposure to a high salience experience such as novel stress or by manipulations that enhance neural activity levels in vivo or in vitro. Together these data demonstrate that experience salience, through alterations in afferent synaptic activity, induces rapid changes in endocannabinoid signaling.

  19. Down Regulation of Asparagine Synthetase and 3-Phosphoglycerate Dehydrogenase, and the Up-Regulation of Serine Dehydratase in Rat Liver from Intake of Excess Amount of Leucine Are Not Related to Leucine-Caused Amino Acid Imbalance.

    PubMed

    Yoshimura, Ryoji; Takai, Marie; Namaki, Hiroya; Minami, Kimiko; Imamura, Wataru; Kato, Hisanori; Kamei, Yasutomi; Kanamoto, Ryuhei

    2015-01-01

    Asparagine synthetase (ASNS), 3-phosphoglycerate dehydrogenase (PHGDH) and serine dehydratase (SDS) in rat liver are expressed in response to protein and amino acid intake. In the present study, we examined the expression of these enzymes in relation to amino acid imbalance caused by leucine. Rats were subjected to leucine administration in the diet or orally between meals. Consumption of more than 2% leucine in a 6% casein diet suppressed food intake and caused growth retardation in a dose-dependent manner, but this was not seen in a 12% or 40% casein diet. ASNS and PHGDH expression in the liver was significantly induced by the 6% casein diet and was suppressed by leucine in a dose-dependent manner, whereas the SDS expression was induced. These effects were leucine specific and not seen with ingestion of isoleucine or valine. However, leucine orally administered between meals did not change the food intake or growth of rats fed a 6% casein die, though it similarly affected the expression of ASNS, PHGDH and SDS in the liver. These results suggest that the growth retardation caused by leucine imbalance was mainly because of the suppression of food intake, and demonstrated that there are no causal relationships between ASNS, PHGDH and SDS expression and amino acid imbalance caused by leucine.

  20. Increased synthesis of eicosanoids by human monocytes following leucine and methionine enkephalin administration

    SciTech Connect

    Wiederhold, M.D.; Ou, D.W.

    1986-03-05

    Regulation of eicosanoid biosynthesis by neuropeptides was investigated in human peripheral blood monocytes from normal donors. Metabolites of /sup 3/H-arachidonic acid (/sup 3/H-AA) were analyzed by thin layer and high pressure liquid chromatography following exposure to 0.2 ..mu..gm/ml and 2.0 ..mu..gm/ml of leucine (L-ENK) and methionine (M-ENK) enkephalin. Supernatants of cultured cells were analyzed. The data indicate that both leucine and methionine enkephalin can stimulate eicosanoid biosynthesis in human monocytes, and may indicate a possible regulatory mechanism between the central nervous system and the reticuloendothelial system.

  1. Measurement of L-(1-/sup 14/C)leucine kinetics in splanchnic and leg tissues in humans. Effect of amino acid infusion

    SciTech Connect

    Gelfand, R.A.; Glickman, M.G.; Castellino, P.; Louard, R.J.; DeFronzo, R.A.

    1988-10-01

    Although whole-body leucine flux is widely measured to study body protein turnover in humans, the contribution of specific tissues to the total-body measurement remains unknown. By combining the organ-balance technique with the systemic infusion of L-(1-14C)leucine, we quantitated leucine production and disposal by splanchnic and leg tissues and by the whole body, simultaneously, in six normal men before and during amino acid infusion. At steady state, disposal of arterial leucine by splanchnic and leg tissues was calculated from the percent extraction (E) of L-(1-14C)leucine counts: uptake = E x (Leu)a x flow. Tissue release of cold leucine (from protein turnover) into vein was calculated as the difference between leucine uptake and the net tissue leucine balance. In the postabsorptive state, despite substantial (P less than .01) extraction of L-(1-14C)leucine by splanchnic (23 +/- 1%) and leg (18 +/- 2%) tissues, net leucine balance across both tissue beds was small, indicating active simultaneous disposal and production of leucine at nearly equivalent rates. Splanchnic tissues accounted for approximately 50% of the measured total-body leucine flux. During amino acid infusion, the net leucine balance across splanchnic and leg tissues became positive, reflecting not only an increase in leucine uptake but also a marked suppression (by approximately 50%, P less than .02) of cold leucine release. This reduction in splanchnic and leg leucine release was indicated by a sharp decline in whole-body endogenous leucine flux.

  2. Leucine Promotes Proliferation and Differentiation of Primary Preterm Rat Satellite Cells in Part through mTORC1 Signaling Pathway.

    PubMed

    Dai, Jie-Min; Yu, Mu-Xue; Shen, Zhen-Yu; Guo, Chu-Yi; Zhuang, Si-Qi; Qiu, Xiao-Shan

    2015-05-08

    Signaling through the mammalian target of rapamycin (mTOR) in response to leucine modulates many cellular and developmental processes. However, in the context of satellite cell proliferation and differentiation, the role of leucine and mTORC1 is less known. This study investigates the role of leucine in the process of proliferation and differentiation of primary preterm rat satellite cells, and the relationship with mammalian target of rapamycin complex 1 (mTORC1) activation. Dissociation of primary satellite cells occurred with type I collagenase and trypsin, and purification, via different speed adherence methods. Satellite cells with positive expression of Desmin were treated with leucine and rapamycin. We observed that leucine promoted proliferation and differentiation of primary satellite cells and increased the phosphorylation of mTOR. Rapamycin inhibited proliferation and differentiation, as well as decreased the phosphorylation level of mTOR. Furthermore, leucine increased the expression of MyoD and myogenin while the protein level of MyoD decreased due to rapamycin. However, myogenin expressed no affect by rapamycin. In conclusion, leucine may up-regulate the activation of mTORC1 to promote proliferation and differentiation of primary preterm rat satellite cells. We have shown that leucine promoted the differentiation of myotubes in part through the mTORC1-MyoD signal pathway.

  3. The actions of exogenous leucine on mTOR signalling and amino acid transporters in human myotubes

    PubMed Central

    2011-01-01

    Background The branched-chain amino acid (BCAA) leucine has been identified to be a key regulator of skeletal muscle anabolism. Activation of anabolic signalling occurs via the mammalian target of rapamycin (mTOR) through an undefined mechanism. System A and L solute carriers transport essential amino acids across plasma membranes; however it remains unknown whether an exogenous supply of leucine regulates their gene expression. The aim of the present study was to investigate the effects of acute and chronic leucine stimulation of anabolic signalling and specific amino acid transporters, using cultured primary human skeletal muscle cells. Results Human myotubes were treated with leucine, insulin or co-treated with leucine and insulin for 30 min, 3 h or 24 h. Activation of mTOR signalling kinases were examined, together with putative nutrient sensor human vacuolar protein sorting 34 (hVps34) and gene expression of selected amino acid transporters. Phosphorylation of mTOR and p70S6K was transiently increased following leucine exposure, independently to insulin. hVps34 protein expression was also significantly increased. However, genes encoding amino acid transporters were differentially regulated by insulin and not leucine. Conclusions mTOR signalling is transiently activated by leucine within human myotubes independently of insulin stimulation. While this occurred in the absence of changes in gene expression of amino acid transporters, protein expression of hVps34 increased. PMID:21702994

  4. Leucine Promotes Proliferation and Differentiation of Primary Preterm Rat Satellite Cells in Part through mTORC1 Signaling Pathway

    PubMed Central

    Dai, Jie-Min; Yu, Mu-Xue; Shen, Zhen-Yu; Guo, Chu-Yi; Zhuang, Si-Qi; Qiu, Xiao-Shan

    2015-01-01

    Signaling through the mammalian target of rapamycin (mTOR) in response to leucine modulates many cellular and developmental processes. However, in the context of satellite cell proliferation and differentiation, the role of leucine and mTORC1 is less known. This study investigates the role of leucine in the process of proliferation and differentiation of primary preterm rat satellite cells, and the relationship with mammalian target of rapamycin complex 1 (mTORC1) activation. Dissociation of primary satellite cells occurred with type I collagenase and trypsin, and purification, via different speed adherence methods. Satellite cells with positive expression of Desmin were treated with leucine and rapamycin. We observed that leucine promoted proliferation and differentiation of primary satellite cells and increased the phosphorylation of mTOR. Rapamycin inhibited proliferation and differentiation, as well as decreased the phosphorylation level of mTOR. Furthermore, leucine increased the expression of MyoD and myogenin while the protein level of MyoD decreased due to rapamycin. However, myogenin expressed no affect by rapamycin. In conclusion, leucine may up-regulate the activation of mTORC1 to promote proliferation and differentiation of primary preterm rat satellite cells. We have shown that leucine promoted the differentiation of myotubes in part through the mTORC1-MyoD signal pathway. PMID:26007333

  5. Childhood maltreatment and adult psychopathology: pathways to hypothalamic-pituitary-adrenal axis dysfunction

    PubMed Central

    Mello, Marcelo F.; Faria, Alvaro A.; Mello, Andrea F.; Carpenter, Linda L.; Tyrka, Audrey R.; Price, Lawrence H.

    2015-01-01

    Objective The aim of this paper was to examine the relationship between childhood maltreatment and adult psychopathology, as reflected in hypothalamic-pituitary-adrenal axis dysfunction. Method A selective review of the relevant literature was undertaken in order to identify key and illustrative research findings. Results There is now a substantial body of preclinical and clinical evidence derived from a variety of experimental paradigms showing how early-life stress is related to hypothalamic-pituitary-adrenal axis function and psychological state in adulthood, and how that relationship can be modulated by other factors. Discussion The risk for adult psychopathology and hypothalamic-pituitary-adrenal axis dysfunction is related to a complex interaction among multiple experiential factors, as well as to susceptibility genes that interact with those factors. Although acute hypothalamic-pituitary-adrenal axis responses to stress are generally adaptive, excessive responses can lead to deleterious effects. Early-life stress alters hypothalamic-pituitary-adrenal axis function and behavior, but the pattern of hypothalamic-pituitary-adrenal dysfunction and psychological outcome in adulthood reflect both the characteristics of the stressor and other modifying factors. Conclusion Research to date has identified multiple determinants of the hypothalamic-pituitary-adrenal axis dysfunction seen in adults with a history of childhood maltreatment or other early-life stress. Further work is needed to establish whether hypothalamic-pituitary-adrenal axis abnormalities in this context can be used to develop risk endophenotypes for psychiatric and physical illnesses. PMID:19967199

  6. A treasure trove of hypothalamic neurocircuitries governing body weight homeostasis.

    PubMed

    Vianna, Claudia R; Coppari, Roberto

    2011-01-01

    Changes in physical activities and feeding habits have transformed the historically rare disease of obesity into a modern metabolic pandemic. Obesity occurs when energy intake exceeds energy expenditure over time. This energy imbalance significantly increases the risk for cardiovascular disease and type 2 diabetes mellitus and as such represents an enormous socioeconomic burden and health threat. To combat obesity, a better understanding of the molecular mechanisms and neurocircuitries underlying normal body weight homeostasis is required. In the 1940s, pioneering lesion experiments unveiled the importance of medial and lateral hypothalamic structures. In the 1980s and 1990s, several neuropeptides and peripheral hormones critical for appropriate feeding behavior, energy expenditure, and hence body weight homeostasis were identified. In the 2000s, results from metabolic analyses of genetically engineered mice bearing mutations only in selected neuronal groups greatly advanced our knowledge of the peripheral/brain feedback-loop modalities by which central neurons control energy balance. In this review, we will summarize these recent progresses with particular emphasis on the biochemical identities of hypothalamic neurons and molecular components underlying normal appetite, energy expenditure, and body weight homeostasis. We will also parse which of those neurons and molecules are critical components of homeostatic adaptive pathways against obesity induced by hypercaloric feeding.

  7. [Symptomatic hypersomnia due to orexin deficiency in hypothalamic lesions].

    PubMed

    Kanbayashi, Takashi; Arii, Junko; Kubota, Hiroaki; Yano, Tamami; Kashiwagi, Mitsuru; Yoshikawa, Sousuke; Tohyama, Jun; Sawaishi, Yukio

    2006-09-01

    Narcolepsy is characterized by excessive daytime sleepiness (EDS), cataplexy and other abnormal manifestations of REM sleep. Recently, it was discovered that the pathophysiology of idiopathic narcolepsy-cataplexy is linked to orexin ligand deficiency in the brain and cerebrospinal fluid. Orexin neurons localize in the posterior hypothalamic area, which was previously described as "waking center" by von Economo in 1920s. Hypersomnia due to orexin ligand deficiency can also occur during the course of other neurological conditions, such as hypothalamic tumor, encephalopathy and demyelinating disorder (i.e. symptomatic hypersomnia). We experienced 8 pediatric cases with symptomatic hypersomnia. These cases were diagnosed as brain tumor (n = 2), head trauma (n = 1), encephalopathy (n = 1), demyelinating disorder (n = 3) and infarction (n = 1). Six pediatric cases with orexin measurements from the literatures were additionally included and total 14 cases were studied. Although it is difficult to rule out the comorbidity of idiopathic narcolepsy in some cases, a review of the case histories reveals numerous unquestionable cases of symptomatic hypersomnia. In these cases, the occurrences of the hypersomnia run parallel with the rise and fall of the causative diseases. Most of symptomatic hypersomnia cases show both extended nocturnal sleep time and EDS consisting of prolonged sleep episodes of NREM sleep. The features of nocturnal sleep and EDS in symptomatic hypersomnia are more similar to idiopathic hypersomnia than to narcolepsy.

  8. Ghrelin Regulates Glucose and Glutamate Transporters in Hypothalamic Astrocytes.

    PubMed

    Fuente-Martín, Esther; García-Cáceres, Cristina; Argente-Arizón, Pilar; Díaz, Francisca; Granado, Miriam; Freire-Regatillo, Alejandra; Castro-González, David; Ceballos, María L; Frago, Laura M; Dickson, Suzanne L; Argente, Jesús; Chowen, Julie A

    2016-03-30

    Hypothalamic astrocytes can respond to metabolic signals, such as leptin and insulin, to modulate adjacent neuronal circuits and systemic metabolism. Ghrelin regulates appetite, adiposity and glucose metabolism, but little is known regarding the response of astrocytes to this orexigenic hormone. We have used both in vivo and in vitro approaches to demonstrate that acylated ghrelin (acyl-ghrelin) rapidly stimulates glutamate transporter expression and glutamate uptake by astrocytes. Moreover, acyl-ghrelin rapidly reduces glucose transporter (GLUT) 2 levels and glucose uptake by these glial cells. Glutamine synthetase and lactate dehydrogenase decrease, while glycogen phosphorylase and lactate transporters increase in response to acyl-ghrelin, suggesting a change in glutamate and glucose metabolism, as well as glycogen storage by astrocytes. These effects are partially mediated through ghrelin receptor 1A (GHSR-1A) as astrocytes do not respond equally to desacyl-ghrelin, an isoform that does not activate GHSR-1A. Moreover, primary astrocyte cultures from GHSR-1A knock-out mice do not change glutamate transporter or GLUT2 levels in response to acyl-ghrelin. Our results indicate that acyl-ghrelin may mediate part of its metabolic actions through modulation of hypothalamic astrocytes and that this effect could involve astrocyte mediated changes in local glucose and glutamate metabolism that alter the signals/nutrients reaching neighboring neurons.

  9. Ghrelin Regulates Glucose and Glutamate Transporters in Hypothalamic Astrocytes

    PubMed Central

    Fuente-Martín, Esther; García-Cáceres, Cristina; Argente-Arizón, Pilar; Díaz, Francisca; Granado, Miriam; Freire-Regatillo, Alejandra; Castro-González, David; Ceballos, María L.; Frago, Laura M.; Dickson, Suzanne L.; Argente, Jesús; Chowen, Julie A.

    2016-01-01

    Hypothalamic astrocytes can respond to metabolic signals, such as leptin and insulin, to modulate adjacent neuronal circuits and systemic metabolism. Ghrelin regulates appetite, adiposity and glucose metabolism, but little is known regarding the response of astrocytes to this orexigenic hormone. We have used both in vivo and in vitro approaches to demonstrate that acylated ghrelin (acyl-ghrelin) rapidly stimulates glutamate transporter expression and glutamate uptake by astrocytes. Moreover, acyl-ghrelin rapidly reduces glucose transporter (GLUT) 2 levels and glucose uptake by these glial cells. Glutamine synthetase and lactate dehydrogenase decrease, while glycogen phosphorylase and lactate transporters increase in response to acyl-ghrelin, suggesting a change in glutamate and glucose metabolism, as well as glycogen storage by astrocytes. These effects are partially mediated through ghrelin receptor 1A (GHSR-1A) as astrocytes do not respond equally to desacyl-ghrelin, an isoform that does not activate GHSR-1A. Moreover, primary astrocyte cultures from GHSR-1A knock-out mice do not change glutamate transporter or GLUT2 levels in response to acyl-ghrelin. Our results indicate that acyl-ghrelin may mediate part of its metabolic actions through modulation of hypothalamic astrocytes and that this effect could involve astrocyte mediated changes in local glucose and glutamate metabolism that alter the signals/nutrients reaching neighboring neurons. PMID:27026049

  10. Molecular interrogation of hypothalamic organization reveals distinct dopamine neuronal subtypes.

    PubMed

    Romanov, Roman A; Zeisel, Amit; Bakker, Joanne; Girach, Fatima; Hellysaz, Arash; Tomer, Raju; Alpár, Alán; Mulder, Jan; Clotman, Frédéric; Keimpema, Erik; Hsueh, Brian; Crow, Ailey K; Martens, Henrik; Schwindling, Christian; Calvigioni, Daniela; Bains, Jaideep S; Máté, Zoltán; Szabó, Gábor; Yanagawa, Yuchio; Zhang, Ming-Dong; Rendeiro, Andre; Farlik, Matthias; Uhlén, Mathias; Wulff, Peer; Bock, Christoph; Broberger, Christian; Deisseroth, Karl; Hökfelt, Tomas; Linnarsson, Sten; Horvath, Tamas L; Harkany, Tibor

    2017-02-01

    The hypothalamus contains the highest diversity of neurons in the brain. Many of these neurons can co-release neurotransmitters and neuropeptides in a use-dependent manner. Investigators have hitherto relied on candidate protein-based tools to correlate behavioral, endocrine and gender traits with hypothalamic neuron identity. Here we map neuronal identities in the hypothalamus by single-cell RNA sequencing. We distinguished 62 neuronal subtypes producing glutamatergic, dopaminergic or GABAergic markers for synaptic neurotransmission and harboring the ability to engage in task-dependent neurotransmitter switching. We identified dopamine neurons that uniquely coexpress the Onecut3 and Nmur2 genes, and placed these in the periventricular nucleus with many synaptic afferents arising from neuromedin S(+) neurons of the suprachiasmatic nucleus. These neuroendocrine dopamine cells may contribute to the dopaminergic inhibition of prolactin secretion diurnally, as their neuromedin S(+) inputs originate from neurons expressing Per2 and Per3 and their tyrosine hydroxylase phosphorylation is regulated in a circadian fashion. Overall, our catalog of neuronal subclasses provides new understanding of hypothalamic organization and function.

  11. Early effects of cranial irradiation on hypothalamic-pituitary function

    SciTech Connect

    Lam, K.S.; Tse, V.K.; Wang, C.; Yeung, R.T.; Ma, J.T.; Ho, J.H.

    1987-03-01

    Hypothalamic-pituitary function was studied in 31 patients before and after cranial irradiation for nasopharyngeal carcinoma. The estimated radiotherapy (RT) doses to the hypothalamus and pituitary were 3979 +/- 78 (+/- SD) and 6167 +/- 122 centiGrays, respectively. All patients had normal pituitary function before RT. One year after RT, there was a significant decrease in the integrated serum GH response to insulin-induced hypoglycemia. In the male patients, basal serum FSH significantly increased, while basal serum LH and testosterone did not change. Moreover, in response to LHRH, the integrated FSH response was increased while that of LH was decreased. Such discordant changes in FSH and LH may be explained by a defect in LHRH pulsatile release involving predominantly a decrease in pulse frequency. The peak serum TSH response to TRH became delayed in 28 patients, suggesting a defect in TRH release. Twenty-one patients were reassessed 2 yr after RT. Their mean basal serum T4 and plasma cortisol levels had significantly decreased. Hyperprolactinemia associated with oligomenorrhoea was found in 3 women. Further impairment in the secretion of GH, FSH, LH, TSH, and ACTH had occurred, and 4 patients had hypopituitarism. Thus, progressive impairment in hypothalamic-pituitary function occurs after cranial irradiation and can be demonstrated as early as 1 yr after RT.

  12. Few isolated neurons in hypothalamic hamartomas may cause gelastic seizures.

    PubMed

    Waldau, Ben; McLendon, Roger E; Fuchs, Herbert E; George, Timothy M; Grant, Gerald A

    2009-01-01

    Hypothalamic hamartomas (HHs) are congenital, benign masses in the hypothalamus and tuber cinereum that may cause central precocious puberty and gelastic seizures. Nodules of small neurons are thought to be a universal feature of the microarchitecture of HH lesions associated with epilepsy. Here we describe the case of a 5-year-old boy with gelastic seizures who underwent resection of a HH that contained nodules of glial cells, but only few, randomly distributed neurons. HHs that contain few or no neurons have only been reported thus far in cases associated with precocious puberty. This case demonstrates that few solitary neurons in HHs can drive the development of gelastic seizures, and nodules of small neurons may not be a universal feature of HHs associated with epilepsy. This finding is clinically important since hypothalamic hamartomas with rare neurons can easily be misdiagnosed as pilocytic astrocytomas or subependymomas if their presence is overlooked. A neuronal stain is helpful in making the correct diagnosis in these cases.

  13. Endoscopic disconnection of hypothalamic astrocytoma causing gelastic epilepsy. Case report.

    PubMed

    Park, Young Seok; Lee, Yun Ho; Shim, Kyu-Won; Kim, Dong-Seok; Lee, Joon Soo; Kim, Heung Dong

    2009-08-01

    The authors report on a case of juvenile pilocytic astrocytoma (JPA) and concomitant hypothalamic hamartoma (HH) with gelastic epilepsy that was successfully treated with endoscopic disconnection. This 6-year-old girl presented with prolonged, medically intractable gelastic seizures that were often followed by generalized tonic seizures. An enhancing, low-grade hypothalamic tumor was identified on MR images obtained when she was 11 months old, but no surgical intervention was attempted at that time apart from bur hole drainage of a chronic subdural hemorrhage. In the first surgery, performed when she was 6 years of age, the authors attempted disconnection and tumor sampling; the lesion was revealed to be a JPA. A second endoscopic disconnection was performed 1 year later to improve seizure control and obtain a pathological specimen from the nonenhancing contralateral side. The pathological results after the second surgery revealed that the enhancing mass was a spontaneously regressing JPA and the contralateral nonenhancing mass was an HH. The HH was found as latent tumor and the JPA was the mass causing gelastic epilepsy. To the authors' knowledge, this is the first report of a patient with a spontaneously regressing JPA and concomitant HH, both of which were treated by endoscopic disconnection.

  14. Oestrogen Modulates Hypothalamic Control of Energy Homeostasis Through Multiple Mechanisms

    PubMed Central

    Roepke, Troy A.

    2009-01-01

    The control of energy homeostasis in women is correlated with the anorectic effects of oestrogen, which can attenuate body weight gain and reduce food intake in rodent models. This review will investigate the multiple signalling pathways and cellular targets that oestrogen utilises to control energy homeostasis in the hypothalamus. Oestrogen affects all of the hypothalamic nuclei that control energy homeostasis. Oestrogen controls the activity of hypothalamic neurones through gene regulation and neuronal excitability. Oestrogen’s primary cellular pathway is the control of gene transcription through the classical ERs (ERα and ERβ) with ERα having the primary role in energy homeostasis. Oestrogen also controls energy homeostasis through membrane-mediated events via membrane-associated ERs or a novel, putative membrane ER that is coupled to G-proteins. Therefore, oestrogen has at least two receptors with multiple signalling and transcriptional pathways to activate during immediate and long-term anorectic effects. Ultimately, it is the interactions of all the receptor-mediated processes in hypothalamus and other areas of the CNS that will determine the anorectic effects of oestrogen and its control of energy homeostasis. PMID:19076267

  15. [Behavioral specialization of cortical and hypothalamic neurons in the rabbit].

    PubMed

    Shevchenko, D G

    1987-01-01

    Behavioural specialization was analyzed of hypothalamic and limbic neurones, with their activity recorded in rabbits during food-acquisition behaviour. The neurones with activity changed during staying of the animal in a definite place of the cage or during behavioural acts, characteristic of a specific behaviour in the cage, are considered as specialized in relation to the most "new" systems, acquired by the rabbit directly during learning of the given behaviour. Neurones with the activity changed with rabbit's turns, i.e. connected with behavioural acts, which the rabbit has not specially learnt, are considered specialized in relation to more "old" inborn systems. Neurones, in which no constant connection with any part of the studied behaviour was observed, are related to the most "ancient" systems. Comparison of the number of hypothalamic and limbic neurones of different groups showed that in the cortex there were some more neurones specialized in relation to behavioural acts, which were formed directly during learning of the rabbit in the experimental cage.

  16. Ca2+/calmodulin system: participation on rat sexual hypothalamic differentiation.

    PubMed

    Rodríguez-Medina, M; Canchola, E; Vergara-Onofre, M; Rosado, A

    1993-11-01

    Modifications of male rat hypothalamic sexual differentiation after neonatal administration of drugs that participate on the Ca2+/calmodulin system (haloperidol, trifluoperazine, penfluridol, pimozide, and verapamil) were studied. Pups treated 72 h after birth were behaviorally tested on day 120 of extrauterine life. Five tests for homotypical behavior were conducted. Afterwards animals were castrated and tested twice for heterotypical (female) behavior under replacement hormonal therapy. Fifty percent (80% in the case of pimozide) of all treated males showed lordotic behavior compared with none of the controls. Haloperidol (39%, lordosis quotient) and pimozide (40%, lordosis quotient) were more active than the others. Results obtained with verapamil were not statistically different from the controls. Pimozide was the most active agent influencing the appetitive masculine behavior (mount latency, intromission latency, and postejaculatory interval). Verapamil was more efficient than the rest of the drugs on the consummatory behavior (mount latency, intromission frequency, interintromission interval, and ejaculatory latency). Our results support the participation of the Ca2+/calmodulin system in hypothalamic sexual differentiation and in the differential modulation of the masculine and feminine behavioral patterns.

  17. Single-Cell RNA-Seq Reveals Hypothalamic Cell Diversity.

    PubMed

    Chen, Renchao; Wu, Xiaoji; Jiang, Lan; Zhang, Yi

    2017-03-28

    The hypothalamus is one of the most complex brain structures involved in homeostatic regulation. Defining cell composition and identifying cell-type-specific transcriptional features of the hypothalamus is essential for understanding its functions and related disorders. Here, we report single-cell RNA sequencing results of adult mouse hypothalamus, which defines 11 non-neuronal and 34 neuronal cell clusters with distinct transcriptional signatures. Analyses of cell-type-specific transcriptomes reveal gene expression dynamics underlying oligodendrocyte differentiation and tanycyte subtypes. Additionally, data analysis provides a comprehensive view of neuropeptide expression across hypothalamic neuronal subtypes and uncover Crabp1(+) and Pax6(+) neuronal populations in specific hypothalamic sub-regions. Furthermore, we found food deprivation exhibited differential transcriptional effects among the different neuronal subtypes, suggesting functional specification of various neuronal subtypes. Thus, the work provides a comprehensive transcriptional perspective of adult hypothalamus, which serves as a valuable resource for dissecting cell-type-specific functions of this complex brain region.

  18. Hypothalamic leptin-neurotensin-hypocretin neuronal networks in zebrafish.

    PubMed

    Levitas-Djerbi, Talia; Yelin-Bekerman, Laura; Lerer-Goldshtein, Tali; Appelbaum, Lior

    2015-04-01

    Neurotensin (NTS) is a 13 amino acid neuropeptide that is expressed in the hypothalamus. In mammals, NTS-producing neurons that express leptin receptor (LepRb) regulate the function of hypocretin/orexin (HCRT) and dopamine neurons. Thus, the hypothalamic leptin-NTS-HCRT neuronal network orchestrates key homeostatic output, including sleep, feeding, and reward. However, the intricate mechanisms of the circuitry and the unique role of NTS-expressing neurons remain unclear. We studied the NTS neuronal networks in zebrafish and cloned the genes encoding the NTS neuropeptide and receptor (NTSR). Similar to mammals, the ligand is expressed primarily in the hypothalamus, while the receptor is expressed widely throughout the brain in zebrafish. A portion of hypothalamic nts-expressing neurons are inhibitory and some coexpress leptin receptor (lepR1). As in mammals, NTS and HCRT neurons are localized adjacently in the hypothalamus. To track the development and axonal projection of NTS neurons, the NTS promoter was isolated. Transgenesis and double labeling of NTS and HCRT neurons showed that NTS axons project toward HCRT neurons, some of which express ntsr. Moreover, another target of NTS neurons is ntsr-expressing dopaminergeric neurons. These findings suggest structural circuitry between leptin, NTS, and hypocretinergic or dopaminergic neurons and establish the zebrafish as a model to study the role of these neuronal circuits in the regulation of feeding, sleep, and reward.

  19. Hypothalamic proopiomelanocortin processing and the regulation of energy balance.

    PubMed

    Wardlaw, Sharon L

    2011-06-11

    Hypothalamic proopiomelanocortin (POMC) neurons play a key role in regulating energy balance and neuroendocrine function. Much attention has been focused on the regulation of POMC gene expression with less emphasis on regulated peptide processing. This is particularly important given the complexity of posttranslational POMC processing which is essential for the generation of biologically active MSH peptides. Mutations that impair POMC sorting and processing are associated with obesity in humans and in animals. Specifically, mutations in the POMC processing enzymes prohormone convertase 1/3 (PC1/3) and in carboxypeptidase E (CPE) and in the α-MSH degrading enzyme, PRCP, are associated with changes in energy balance. There is increasing evidence that POMC processing is regulated with respect to energy balance. Studies have implicated both the leptin and insulin signaling pathways in the regulation of POMC at various steps in the processing pathway. This article will review the role of hypothalamic POMC in regulating energy balance with a focus on POMC processing. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. A Treasure Trove of Hypothalamic Neurocircuitries Governing Body Weight Homeostasis

    PubMed Central

    Vianna, Claudia R.; Coppari, Roberto

    2011-01-01

    Changes in physical activities and feeding habits have transformed the historically rare disease of obesity into a modern metabolic pandemic. Obesity occurs when energy intake exceeds energy expenditure over time. This energy imbalance significantly increases the risk for cardiovascular disease and type 2 diabetes mellitus and as such represents an enormous socioeconomic burden and health threat. To combat obesity, a better understanding of the molecular mechanisms and neurocircuitries underlying normal body weight homeostasis is required. In the 1940s, pioneering lesion experiments unveiled the importance of medial and lateral hypothalamic structures. In the 1980s and 1990s, several neuropeptides and peripheral hormones critical for appropriate feeding behavior, energy expenditure, and hence body weight homeostasis were identified. In the 2000s, results from metabolic analyses of genetically engineered mice bearing mutations only in selected neuronal groups greatly advanced our knowledge of the peripheral/brain feedback-loop modalities by which central neurons control energy balance. In this review, we will summarize these recent progresses with particular emphasis on the biochemical identities of hypothalamic neurons and molecular components underlying normal appetite, energy expenditure, and body weight homeostasis. We will also parse which of those neurons and molecules are critical components of homeostatic adaptive pathways against obesity induced by hypercaloric feeding. PMID:21068159

  1. Disruption of neurogenesis by hypothalamic inflammation in obesity or aging.

    PubMed

    Purkayastha, Sudarshana; Cai, Dongsheng

    2013-12-01

    Adult neural stem cells contribute to neurogenesis and plasticity of the brain which is essential for central regulation of systemic homeostasis. Damage to these homeostatic components, depending on locations in the brain, poses threat to impaired neurogenesis, neurodegeneration, cognitive loss and energy imbalance. Recent research has identified brain metabolic inflammation via proinflammatory IκB kinase-β (IKKβ) and its downstream nuclear transcription factor NF-κB pathway as a non-classical linker of metabolic and neurodegenerative disorders. Chronic activation of the pathway results in impairment of energy balance and nutrient metabolism, impediment of neurogenesis, neural stem cell proliferation and differentiation, collectively converging on metabolic and cognitive decline. Hypothalamic IKKβ/NF-κB via inflammatory crosstalk between microglia and neurons has been discovered to direct systemic aging by inhibiting the production of gonadotropin-releasing hormone (GnRH) and inhibition of inflammation or GnRH therapy could revert aging related degenerative symptoms at least in part. This article reviews the crucial role of hypothalamic inflammation in affecting neural stem cells which mediates the neurodegenerative mechanisms of causing metabolic derangements as well as aging-associated disorders or diseases.

  2. Hypothalamic-Pituitary Autoimmunity and Traumatic Brain Injury

    PubMed Central

    Guaraldi, Federica; Grottoli, Silvia; Arvat, Emanuela; Ghigo, Ezio

    2015-01-01

    Background: Traumatic brain injury (TBI) is a leading cause of secondary hypopituitarism in children and adults, and is responsible for impaired quality of life, disabilities and compromised development. Alterations of pituitary function can occur at any time after the traumatic event, presenting in various ways and evolving during time, so they require appropriate screening for early detection and treatment. Although the exact pathophysiology is unknown, several mechanisms have been hypothesized, including hypothalamic-pituitary autoimmunity (HP-A). The aim of this study was to systematically review literature on the association between HP-A and TBI-induced hypopituitarism. Major pitfalls related to the HP-A investigation were also discussed. Methods: The PubMed database was searched with a string developed for this purpose, without temporal or language limits, for original articles assessing the association of HP-A and TBI-induced hypopituitarism. Results: Three articles from the same group met the inclusion criteria. Anti-pituitary and anti-hypothalamic antibodies were detected using indirect immunofluorescence in a significant number of patients with acute and chronic TBI. Elevated antibody titer was associated with an increased risk of persistent hypopituitarism, especially somatotroph and gonadotroph deficiency, while no correlations were found with clinical parameters. Conclusion: HPA seems to contribute to TBI-induced pituitary damage, although major methodological issues need to be overcome and larger studies are warranted to confirm these preliminary data. PMID:26239463

  3. [A successful surgical case of a hypothalamic hamartoma with gelastic seizure: a case report].

    PubMed

    Fujita, Tomoaki; Nishimura, Shinjitsu; Sakata, Hiroyuki; Furuno, Yuichi; Mino, Masaki; Hori, Emiko; Kaimori, Mitsuomi; Shirane, Reizou; Nishijima, Michiharu

    2009-08-01

    Gelastic seizure is a rare form of epilepsy defined as automatic bouts of laughter without mirth commonly associated with a hypothalamic hamartoma. Surgical treatment of hypothalamic hamartomas is associated with a high risk of complications because of the close vicinity of adjacent structures such as the optic tracts and mammillary bodies. This case was an 11-year-old girl who presented with gelastic seizure and complicated partial seizure. She developed gelastic seizure at a frequency of 10 bouts per day. She was found to have an elliptical mass close to the left hypothalamus. The signal intensity on magnetic resonance imaging (MRI) was consistent with hypothalamic hamartoma. The patient underwent surgical resection by a subtemporal approach. Pathological findings confirmed the diagnosis of hypothalamic hamartoma. Postoperative MRI demonstrated that the hypothalamic hamartoma was successfully resected. Twenty four months after surgery, complicated partial seizure in this patient has improved to Engel's class 1a and gelastic seizure has improved to Engel's class IIIa.

  4. Amphetamine, an appetite suppressant, decreases neuropeptide Y immunoreactivity in rat hypothalamic paraventriculum.

    PubMed

    Hsieh, Yih-Shou; Yang, Shun-Fa; Kuo, Dong-Yih

    2005-04-15

    Amphetamine (AMPH) is a well-known anorectic agent. The mechanism underlying the anorectic response of AMPH has been attributed to its inhibitory effect on hypothalamic neuropeptide Y (NPY), an orexigenic peptide in the brain. However, there is still lack of genomic or in situ immunohistochemical evidence to prove it. The present study was aimed to assess the molecular mechanism of AMPH anorexia by immunostaining of hypothalamic NPY protein in the area of paraventricular nucleus (PVN) and by detecting the change of hypothalamic NPY mRNA level using RT-PCR. Results revealed that an AMPH treatment might reduce the expression of NPY at both transcriptional and posttranslational levels. Comparatively, a treatment of clomipramine, a serotonin transporter inhibitor, was unable to reduce NPY mRNA level, revealing the noninvolvement of hypothalamic NPY gene in serotonin anorexia. Our results provided genomic and in situ immunohistochemical evidence to confirm the mediation of hypothalamic NPY neurons in the anorectic action of AMPH.

  5. A fatty acid-dependent hypothalamic-DVC neurocircuitry that regulates hepatic secretion of triglyceride-rich lipoproteins.

    PubMed

    Yue, Jessica T Y; Abraham, Mona A; LaPierre, Mary P; Mighiu, Patricia I; Light, Peter E; Filippi, Beatrice M; Lam, Tony K T

    2015-01-12

    The brain emerges as a regulator of hepatic triglyceride-rich very-low-density lipoproteins (VLDL-TG). The neurocircuitry involved as well as the ability of fatty acids to trigger a neuronal network to regulate VLDL-TG remain unknown. Here we demonstrate that infusion of oleic acid into the mediobasal hypothalamus (MBH) activates a MBH PKC-δ→KATP-channel signalling axis to suppress VLDL-TG secretion in rats. Both NMDA receptor-mediated transmissions in the dorsal vagal complex (DVC) and hepatic innervation are required for lowering VLDL-TG, illustrating a MBH-DVC-hepatic vagal neurocircuitry that mediates MBH fatty acid sensing. High-fat diet (HFD)-feeding elevates plasma TG and VLDL-TG secretion and abolishes MBH oleic acid sensing to lower VLDL-TG. Importantly, HFD-induced dysregulation is restored with direct activation of either MBH PKC-δ or KATP-channels via the hepatic vagus. Thus, targeting a fatty acid sensing-dependent hypothalamic-DVC neurocircuitry may have therapeutic potential to lower hepatic VLDL-TG and restore lipid homeostasis in obesity and diabetes.

  6. Leucine regulation of glucokinase and ATP synthase sensitizes glucose-induced insulin secretion in pancreatic beta-cells.

    PubMed

    Yang, Jichun; Wong, Ryan K; Park, MieJung; Wu, Jianmei; Cook, Joshua R; York, David A; Deng, Shaoping; Markmann, James; Naji, Ali; Wolf, Bryan A; Gao, Zhiyong

    2006-01-01

    We have recently shown that leucine culture upregulates ATP synthase beta-subunit (ATPSbeta) and increases ATP level, cytosolic Ca(2+), and glucose-induced insulin secretion in rat islets. The aim is to test whether glucokinase expression is also affected in rat islets and its role in glucose sensitization during leucine culture. Leucine culture increased glucose-induced NAD(P)H level at 1 and 2 days but not at 1 week. The half-maximal effective concentration of the glucose response curve for NAD(P)H was left-shifted from 5-7 to 2-3 mmol/l. The effect was dose dependent and rapamycin insensitive. Leucine culture did not affect glyceraldehyde effects on NAD(P)H. Leucine pretreatment for 30 min had no effects on NAD(P)H levels. Leucine culture for 2 days also increased glucose-induced cytosolic Ca(2+) elevation, ATP level, and insulin secretion. Leucine increase of glucokinase mRNA levels occurred as early as day 1 and lasted through 1 week. That of ATPSbeta did not occur until day 2 and lasted through 1 week. Leucine effects on both mRNAs were dose dependent. The upregulation of both genes was confirmed by Western blotting. Leucine culture also increased glucose-induced insulin secretion, ATP level, glucokinase, and ATPSbeta levels of type 2 diabetic human islets. In conclusion, leucine culture upregulates glucokinase, which increases NAD(P)H level, and ATPSbeta, which increases oxidation of NADH and production of ATP. The combined upregulation of both genes increases glucose-induced cytosolic Ca(2+) and insulin secretion.

  7. Increasing leucine concentration stimulates mechanistic target of rapamycin signaling and cell growth in C2C12 skeletal muscle cells.

    PubMed

    Areta, José L; Hawley, John A; Ye, Ji-Ming; Chan, M H Stanley; Coffey, Vernon G

    2014-11-01

    Leucine is a key amino acid for initiating translation in muscle cells, but the dose-dependent effects of leucine on intracellular signaling are poorly characterized. This study examined the effect that increasing doses of leucine would have on changes in mechanistic target of rapamycin (mTOR)-mediated signaling, rates of protein synthesis, and cell size in C2C12 cells. We hypothesized that a leucine "threshold" exists, which represents the minimum stimulus required to initiate mTOR signaling in muscle cells. Acute exposure to 1.5, 3.2, 5.0, and 16.1 mM leucine increased phosphorylation of mTOR(Ser2448) (~1.4-fold; P < .04), 4E-BP1 (Thr37/46) (~1.9-fold; P < .001), and rpS6(Ser235/6) (~2.3-fold; P < .001). However, only p70S6k(Thr389) exhibited a dose-dependent response to leucine with all treatments higher than control (~4-fold; P < .001) and at least 5 mM higher than the 1.5-mM concentration (1.2-fold; P < .02). Rates of protein synthesis were not altered by any treatment. Seven days of exposure to 0.5, 1.5, 5.0, and 16.5 mM leucine resulted in an increase in cell size in at least 5 mM treatments (~1.6-fold, P < .001 vs control). Our findings indicate that even at low leucine concentrations, phosphorylation of proteins regulating translation initiation signaling is enhanced. The phosphorylation of p70S6k(Thr389) follows a leucine dose-response relationship, although this was not reflected by the acute protein synthetic response. Nevertheless, under the conditions of the present study, it appears that leucine concentrations of at least 5 mM are necessary to enhance cell growth.

  8. Glucose Sensing Neurons in the Ventromedial Hypothalamus

    PubMed Central

    Routh, Vanessa H.

    2010-01-01

    Neurons whose activity is regulated by glucose are found in a number of brain regions. Glucose-excited (GE) neurons increase while glucose-inhibited (GI) neurons decrease their action potential frequency as interstitial brain glucose levels increase. We hypothesize that these neurons evolved to sense and respond to severe energy deficit (e.g., fasting) that threatens the brains glucose supply. During modern times, they are also important for the restoration of blood glucose levels following insulin-induced hypoglycemia. Our data suggest that impaired glucose sensing by hypothalamic glucose sensing neurons may contribute to the syndrome known as hypoglycemia-associated autonomic failure in which the mechanisms which restore euglycemia following hypoglycemia become impaired. On the other hand, increased responses of glucose sensing neurons to glucose deficit may play a role in the development of Type 2 Diabetes Mellitus and obesity. This review will discuss the mechanisms by which glucose sensing neurons sense changes in interstitial glucose and explore the roles of these specialized glucose sensors in glucose and energy homeostasis. PMID:22022208

  9. Impact of prolonged leucine supplementation on protein synthesis and lean growth in neonatal pigs

    USDA-ARS?s Scientific Manuscript database

    Most low-birth weight infants experience extrauterine growth failure due to reduced nutrient intake as a result of feeding intolerance. The objective of this study was to determine whether prolonged enteral leucine supplementation improves lean growth in neonatal pigs fed a restricted protein diet. ...

  10. Leucine supplementation has an anabolic effect on proteins in rabbit skin wound and muscle.

    PubMed

    Zhang, Xiao-Jun; Chinkes, David L; Wolfe, Robert R

    2004-12-01

    We investigated the effect of leucine supplementation on protein metabolism in skin wounds and muscle in anesthetized rabbits. l-[ring-(13)C(6)]phenylalanine was infused on d 7 after the ear was scalded, and the scalded ear and uninjured hindlimb were used as arteriovenous units to reflect protein kinetics in skin wounds and muscle. In comparison with a commercially available amino acid solution (10% Travasol), isonitrogenous [1638 micromol/(kg . h)] infusion of the amino acid solution with supplemental leucine to account for 35% of total nitrogen increased the net phenylalanine balance (P < 0.05) in the skin wound and muscle from -6.7 +/- 6.1 to 0.9 +/- 1.4 and from -4.4 +/- 2.4 to -1.0 +/- 0.4 micromol/(100 g . h), respectively. Infusion of leucine alone did not significantly improve the net phenylalanine balance in either skin wounds [-4.0 +/- 4.6 micromol/(100 g . h)] or muscle [-2.7 +/- 0.7 micromol/(100 g . h)]. We conclude that leucine supplementation had an anabolic effect on proteins in skin wounds and muscle, provided that adequate additional amino acids were also available.

  11. 3D Printing of Protein Models in an Undergraduate Laboratory: Leucine Zippers

    ERIC Educational Resources Information Center

    Meyer, Scott C.

    2015-01-01

    An upper-division undergraduate laboratory experiment is described that explores the structure/function relationship of protein domains, namely leucine zippers, through a molecular graphics computer program and physical models fabricated by 3D printing. By generating solvent accessible surfaces and color-coding hydrophobic, basic, and acidic amino…

  12. 3D Printing of Protein Models in an Undergraduate Laboratory: Leucine Zippers

    ERIC Educational Resources Information Center

    Meyer, Scott C.

    2015-01-01

    An upper-division undergraduate laboratory experiment is described that explores the structure/function relationship of protein domains, namely leucine zippers, through a molecular graphics computer program and physical models fabricated by 3D printing. By generating solvent accessible surfaces and color-coding hydrophobic, basic, and acidic amino…

  13. Small-molecule probe using dual signals to monitor leucine aminopeptidase activity.

    PubMed

    Yoon, Hey Young; Shim, So Hee; Baek, Luck Ju; Hong, Jong-In

    2011-04-15

    Leucine aminopeptidases (LAPs) are widely distributed in organisms from bacteria to humans, and play crucial roles in cell maintenance and cell growth. Thus, assays for LAP are necessary for measuring its activity and inhibitor potency. In this Letter, we report a small-molecule probe which exhibits colorimetric and fluorogenic changes according to LAP activity.

  14. Autophagy and leucine promote chronological longevity and respiration proficiency during calorie restriction in yeast

    PubMed Central

    Aris, John P.; Alvers, Ashley L.; Ferraiuolo, Roy A.; Fishwick, Laura K.; Hanvivatpong, Amanda; Hu, Doreen; Kirlew, Christine; Leonard, Michael T.; Losin, Kyle J.; Marraffini, Michelle; Seo, Arnold Y.; Swanberg, Veronica; Westcott, Jennifer L.; Wood, Michael S.; Leeuwenburgh, Christiaan; Dunn, William A.

    2013-01-01

    We have previously shown that autophagy is required for chronological longevity in the budding yeast Saccharomyces cerevisiae. Here we examine the requirements for autophagy during extension of chronological life span (CLS) by calorie restriction (CR). We find that autophagy is upregulated by two CR interventions that extend CLS: water wash CR and low glucose CR. Autophagy is required for full extension of CLS during water wash CR under all growth conditions tested. In contrast, autophagy was not uniformly required for full extension of CLS during low glucose CR, depending on the atg allele and strain genetic background. Leucine status influenced CLS during CR. Eliminating the leucine requirement in yeast strains or adding supplemental leucine to growth media extended CLS during CR. In addition, we observed that both water wash and low glucose CR promote mitochondrial respiration proficiency during aging of autophagy-deficient yeast. In general, the extension of CLS by water wash or low glucose CR was inversely related to respiration deficiency in autophagy-deficient cells. Also, autophagy is required for full extension of CLS under non-CR conditions in buffered media, suggesting that extension of CLS during CR is not solely due to reduced medium acidity. Thus, our findings show that autophagy is: (1) induced by CR, (2) required for full extension of CLS by CR in most cases (depending on atg allele, strain, and leucine availability) and, (3) promotes mitochondrial respiration proficiency during aging under CR conditions. PMID:23337777

  15. Preferential Enrichment of DL-Leucine Using Cocrystal Formation With Oxalic Acid Under Nonequilibrium Crystallization Conditions.

    PubMed

    Manoj, Kochunnoonny; Takahashi, Hiroki; Morita, Yoko; Gonnade, Rajesh G; Iwama, Sekai; Tsue, Hirohito; Tamura, Rui

    2015-07-01

    By utilizing the preferential enrichment (PE) technique, we achieved an improved enantiomeric resolution of DL-leucine (Leu) using a 1:1 cocrystal (DL-) of DL-Leu and oxalic acid. The crystal structure analysis of DL- indicated the occurrence of a novel type of phase transition and subsequent preferential redissolution of one enantiomer from the resulting crystals into solution.

  16. 'Zipbody' leucine zipper-fused Fab in E. coli in vitro and in vivo expression systems.

    PubMed

    Ojima-Kato, Teruyo; Fukui, Kansuke; Yamamoto, Hiroaki; Hashimura, Dai; Miyake, Shiro; Hirakawa, Yuki; Yamasaki, Tomomi; Kojima, Takaaki; Nakano, Hideo

    2016-04-01

    A small antibody fragment, fragment of antigen binding (Fab), is favorable for various immunological assays. However, production efficiency of active Fab in microorganisms depends considerably on the clones. In this study, leucine zipper-peptide pairs that dimerize in parallel (ACID-p1 (LZA)/BASE-p1 (LZB) or c-Jun/c-Fos) were fused to the C-terminus of heavy chain (Hc, VH-CH1) and light chain (Lc, VL-CL), respectively, to accelerate the association of Hc and Lc to form Fab in Escherichia coli in vivo and in vitro expression systems. The leucine zipper-fused Fab named 'Zipbody' was constructed using anti-E. coli O157 monoclonal antibody obtained from mouse hybridoma and produced in both in vitro and in vivo expression systems in an active form, whereas Fab without the leucine zipper fusion was not. Similarly, Zipbody of rabbit monoclonal antibody produced in in vitro expression showed significant activity. The purified, mouse Zipbody produced in the E. coli strain Shuffle T7 Express had specificity toward the antigen; in bio-layer interferometry analysis, the KD value was measured to be 1.5-2.0 × 10(-8) M. These results indicate that leucine zipper fusion to Fab C-termini markedly enhances active Fab formation in E. coli.

  17. An EThcD-Based Method for Discrimination of Leucine and Isoleucine Residues in Tryptic Peptides

    NASA Astrophysics Data System (ADS)

    Zhokhov, Sergey S.; Kovalyov, Sergey V.; Samgina, Tatiana Yu.; Lebedev, Albert T.

    2017-08-01

    An EThcD-based approach for the reliable discrimination of isomeric leucine and isoleucine residues in peptide de novo sequencing procedure has been proposed. A multistage fragmentation of peptide ions was performed with Orbitrap Elite mass spectrometer in electrospray ionization mode. At the first stage, z-ions were produced by ETD or ETcaD fragmentation of doubly or triply charged peptide precursor ions. These primary ions were further fragmented by HCD with broad-band ion isolation, and the resulting w-ions showed different mass for leucine and isoleucine residues. The procedure did not require manual isolation of specific z-ions prior to HCD stage. Forty-three tryptic peptides (3 to 27 residues) obtained by trypsinolysis of human serum albumin (HSA) and gp188 protein were analyzed. To demonstrate a proper solution for radical site migration problem, three non-tryptic peptides were also analyzed. A total of 93 leucine and isoleucine residues were considered and 83 of them were correctly identified. The developed approach can be a reasonable substitution for additional Edman degradation procedure, which is still used in peptide sequencing for leucine and isoleucine discrimination.

  18. Leucine pulses enhance skeletal muscle protein synthesis during continuous feeding in neonatal pigs

    USDA-ARS?s Scientific Manuscript database

    Infants unable to maintain oral feeding can be nourished by orogastric tube. We have shown that orogastric continuous feeding restricts muscle protein synthesis compared with intermittent bolus feeding in neonatal pigs. To determine whether leucine leu infusion can be used to enhance protein synthes...

  19. Prolonged leucine infusion differentially affects tissue protein synthesis in neonatal pigs

    USDA-ARS?s Scientific Manuscript database

    Leucine (Leu) acutely stimulates protein synthesis by activating the mammalian target of rapamycin complex 1 (mTORC1) pathway. To determine whether Leu can stimulate protein synthesis in muscles of different fiber types and visceral tissues of the neonate for a prolonged period and to determine the ...

  20. Role of glucocorticoid-induced leucine zipper (GILZ) in bone acquisition

    USDA-ARS?s Scientific Manuscript database

    Glucocorticoids (GCs) have both anabolic and catabolic effects on bone. However, no GC anabolic effect mediator has been identified to date. In this report, we provide the first evidence that glucocorticoid-induced leucine zipper (GILZ), a GC anti-inflammatory effect mediator, can enhance bone forma...

  1. Toward a Molecular Definition of Leucine-Dependent mTORC1 Activation.

    PubMed

    Abraham, Robert T

    2016-03-08

    The mechanistic target of rapamycin complex 1 (mTORC1) coordinates nutrient availability with cell growth. Recent reports by Sabatini and coworkers (Saxton et al., 2016; Wolfson et al., 2016) characterize a cytoplasmic amino acid receptor that couples the binding of leucine to the activation of mTORC1. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Leucine-protein supplemented recovery feeding enhances subsequent cycling performance in well-trained men.

    PubMed

    Thomson, Jasmine S; Ali, Ajmol; Rowlands, David S

    2011-04-01

    The purpose of this study was to determine whether a practical leucine-protein, high-carbohydrate postexercise feeding regimen could improve recovery, as measured by subsequent cycling performance and mechanistic markers, relative to control feeding. In a crossover, 10 male cyclists performed 2- to 2.5-h interval training bouts on 3 consecutive evenings, ingesting either leucine-protein, high-carbohydrate nutrition (0.1/0.4/1.2/0.2 g·kg(-1)·h(-1); leucine, protein, carbohydrate, fat, respectively) or isocaloric control (0.06/1.6/0.2 g·kg(-1)·h(-1); protein, carbohydrate, fat, respectively) nutrition for 1.5 h postexercise. Throughout the experimental period diet was controlled, energy and macronutrient intake balanced, and protein intake clamped at 1.6 g·kg(-1)·day(-1). The alternate supplement was provided the next morning, thereby isolating the postexercise nutrition effect. Following 39 h of recovery, cyclists performed a repeat-sprint performance test. Postexercise leucine-protein ingestion improved mean sprint power by 2.5% (99% confidence limit, ±2.6%; p = 0.013) and reduced perceived overall tiredness during the sprints by 13% (90% confidence limit, ±9.2%), but perceptions of leg tiredness and soreness were unaffected. Before exercise, creatine-kinase concentration was lowered by 19% (90% confidence limits, ±18%), but lactate dehydrogenase and pressure-pain threshold were unaltered. There was a small reduction in anger (25% ± 18%), but other moods were unchanged. Plasma leucine (3-fold) and essential amino acid (47%) concentrations were elevated postexercise. Net nitrogen balance trended mildly negative in both conditions (mean ± SD: leucine-protein, -20 ± 46 mg·kg(-1) per 24 h; control, -25 ± 36 mg·kg(-1) per 24 h). The ingestion of a leucine-protein supplement along with other high-carbohydrate food following intense training on consecutive days enhances subsequent high-intensity endurance performance and may attenuate

  3. Leucine-rich diet supplementation modulates foetal muscle protein metabolism impaired by Walker-256 tumour

    PubMed Central

    2014-01-01

    Background Cancer-cachexia induces a variety of metabolic disorders of protein turnover and is more pronounced when associated with pregnancy. Tumour-bearing pregnant rats have impaired protein balance, which decreases protein synthesis and increases muscle breakdown. Because branched-chain amino acids, especially leucine, stimulate protein synthesis, we investigated the effect of a leucine-rich diet on protein metabolism in the foetal gastrocnemius muscles of tumour-bearing pregnant rats. Methods Foetuses of pregnant rats with or without Walker 256 tumours were divided into six groups. During the 20 days of the experiment, the pregnant groups were fed with either a control diet (C, control rats; W, tumour-bearing rats; Cp, rats pair-fed the same normoprotein-diet as the W group) or with a leucine-rich diet (L, leucine rats; LW, leucine tumour-bearing rats; and Lp, rats pair-fed the same leucine-rich diet as the LW group). After the mothers were sacrificed, the foetal gastrocnemius muscle samples were resected, and the protein synthesis and degradation and tissue chymotrypsin-like, cathepsin and calpain enzyme activities were assayed. The muscle oxidative enzymes (catalase, glutathione-S-transferase and superoxide dismutase), alkaline phosphatase enzyme activities and lipid peroxidation (malondialdehyde) were also measured. Results Tumour growth led to a reduction in foetal weight associated with decreased serum protein, albumin and glucose levels and low haematocrit in the foetuses of the W group, whereas in the LW foetuses, these changes were less pronounced. Muscle protein synthesis (measured by L-[3H]-phenylalanine incorporation) was reduced in the W foetuses but was restored in the LW group. Protein breakdown (as assessed by tyrosine release) was enhanced in the L and W groups, but chymotrypsin-like activity increased only in group W and tended toward an increase in the LW foetuses. The activity of cathepsin H was significantly higher in the W group foetuses

  4. Depression and alterations in hypothalamic-pituitary-adrenal and hypothalamic-pituitary-thyroid axis function in male abstinent methamphetamine abusers.

    PubMed

    Li, Su-Xia; Yan, Shi-Yan; Bao, Yan-Ping; Lian, Zhi; Qu, Zhi; Wu, Ya-Ping; Liu, Zhi-Min

    2013-09-01

    The present study was to investigate depression and alterations in the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-thyroid (HPT) axis function in methamphetamine (METH) abusers after abstinence. Depression was assessed using the 13-item Beck Depression Inventory (BDI-13) scale; blood samples from in-patients who were METH abusers and age-matched and sex-matched healthy controls were collected. The demographic characteristics and history of METH abuse also was assessed. We found that serum levels of adrenocorticotropic hormone (ACTH) and thyroxine were increased; and serum levels of cortisol, triiodothyronine, and thyroid-stimulating hormone were decreased; and the BDI score was higher in METH abusers compared with control. In addition, there was no correlation between the BDI-13 score and any of hormones of HPA and HPT axis was found. Particularly, we found abnormally higher ACTH level and mismatched with lower cortisol level in abstinent METH abusers. These results indicate that METH abusers and that their HPA and HPT functions are all altered after abstinence. Chronically using METH may destroy the regulatory function of the HPA axis, especially the feedback regulation of cortisol to ACTH. Copyright © 2013 John Wiley & Sons, Ltd.

  5. Leucine pulses enhance skeletal muscle protein synthesis during continuous feeding in neonatal pigs

    PubMed Central

    Boutry, Claire; El-Kadi, Samer W.; Suryawan, Agus; Wheatley, Scott M.; Orellana, Renán A.; Kimball, Scot R.; Nguyen, Hanh V.

    2013-01-01

    Infants unable to maintain oral feeding can be nourished by orogastric tube. We have shown that orogastric continuous feeding restricts muscle protein synthesis compared with intermittent bolus feeding in neonatal pigs. To determine whether leucine infusion can be used to enhance protein synthesis during continuous feeding, neonatal piglets received the same amount of formula enterally by orogastric tube for 25.25 h continuously (CON) with or without LEU or intermittently by bolus every 4 h (BOL). For the CON+LEU group, leucine pulses were administered parenterally (800 μmol·kg−1·h−1) every 4 h. Insulin and glucose concentrations increased after the BOL meal and were unchanged in groups fed continuously. LEU infusion during CON feeding increased plasma leucine after the leucine pulse and decreased essential amino acids compared with CON feeding. Protein synthesis in longissimus dorsi (LD), gastrocnemius, and soleus muscles, but not liver or heart, were greater in CON+LEU and BOL than in the CON group. BOL feeding increased protein synthesis in the small intestine. Muscle S6K1 and 4E-BP1 phosphorylation and active eIF4E·eIF4G complex formation were higher in CON+LEU and BOL than in CON but AMPKα, eIF2α, and eEF2 phosphorylation were unchanged. LC3-II-to-total LC3 ratio was lower in CON+LEU and BOL than in CON, but there were no differences in atrogin-1 and MuRF-1 abundance and FoxO3 phosphorylation. In conclusion, administration of leucine pulses during continuous orogastric feeding in neonates increases muscle protein synthesis by stimulating translation initiation and may reduce protein degradation via the autophagy-lysosome, but not the ubiquitin-proteasome pathway. PMID:23839523

  6. Glycine restores the anabolic response to leucine in a mouse model of acute inflammation.

    PubMed

    Ham, Daniel J; Caldow, Marissa K; Chhen, Victoria; Chee, Annabel; Wang, Xuemin; Proud, Christopher G; Lynch, Gordon S; Koopman, René

    2016-06-01

    Amino acids, especially leucine, potently stimulate protein synthesis and reduce protein breakdown in healthy skeletal muscle and as a result have received considerable attention as potential treatments for muscle wasting. However, the normal anabolic response to amino acids is impaired during muscle-wasting conditions. Although the exact mechanisms of this anabolic resistance are unclear, inflammation and ROS are believed to play a central role. The nonessential amino acid glycine has anti-inflammatory and antioxidant properties and preserves muscle mass in calorie-restricted and tumor-bearing mice. We hypothesized that glycine would restore the normal muscle anabolic response to amino acids under inflammatory conditions. Relative rates of basal and leucine-stimulated protein synthesis were measured using SUnSET methodology 4 h after an injection of 1 mg/kg lipopolysaccharide (LPS). Whereas leucine failed to stimulate muscle protein synthesis in LPS-treated mice pretreated with l-alanine (isonitrogenous control), leucine robustly stimulated protein synthesis (+51%) in mice pretreated with 1 g/kg glycine. The improvement in leucine-stimulated protein synthesis was accompanied by a higher phosphorylation status of mTOR, S6, and 4E-BP1 compared with l-alanine-treated controls. Despite its known anti-inflammatory action in inflammatory cells, glycine did not alter the skeletal muscle inflammatory response to LPS in vivo or in vitro but markedly reduced DHE staining intensity, a marker of oxidative stress, in muscle cross-sections and attenuated LPS-induced wasting in C2C12 myotubes. Our observations in male C57BL/6 mice suggest that glycine may represent a promising nutritional intervention for the attenuation of skeletal muscle wasting. Copyright © 2016 the American Physiological Society.

  7. Pushing product formation to its limit: metabolic engineering of Corynebacterium glutamicum for L-leucine overproduction.

    PubMed

    Vogt, Michael; Haas, Sabine; Klaffl, Simon; Polen, Tino; Eggeling, Lothar; van Ooyen, Jan; Bott, Michael

    2014-03-01

    Using metabolic engineering, an efficient L-leucine production strain of Corynebacterium glutamicum was developed. In the wild type of C. glutamicum, the leuA-encoded 2-isopropylmalate synthase (IPMS) is inhibited by low L-leucine concentrations with a K(i) of 0.4 mM. We identified a feedback-resistant IMPS variant, which carries two amino acid exchanges (R529H, G532D). The corresponding leuA(fbr) gene devoid of the attenuator region and under control of a strong promoter was integrated in one, two or three copies into the genome and combined with additional genomic modifications aimed at increasing L-leucine production. These modifications involved (i) deletion of the gene encoding the repressor LtbR to increase expression of leuBCD, (ii) deletion of the gene encoding the transcriptional regulator IolR to increase glucose uptake, (iii) reduction of citrate synthase activity to increase precursor supply, and (iv) introduction of a gene encoding a feedback-resistant acetohydroxyacid synthase. The production performance of the resulting strains was characterized in bioreactor cultivations. Under fed-batch conditions, the best producer strain accumulated L-leucine to levels exceeding the solubility limit of about 24 g/l. The molar product yield was 0.30 mol L-leucine per mol glucose and the volumetric productivity was 4.3 mmol l⁻¹ h⁻¹. These values were obtained in a defined minimal medium with a prototrophic and plasmid-free strain, making this process highly interesting for industrial application. © 2013 Published by International Metabolic Engineering Society on behalf of International Metabolic Engineering Society.

  8. The distribution of methionine-enkephalin and leucine-enkephalin in the brain and peripheral tissues

    PubMed Central

    Hughes, J.; Kosterlitz, H.W.; Smith, T.W.

    1977-01-01

    1 A method is described for the rapid extraction of opioid peptides from the brain and other tissues. The method is based on acid extraction of tissues followed by adsorption of the extract onto Amberlite XAD-2 resin. Elution with methanol separates the enkephalins and α-endorphin from β-endorphin. 2 Over 90% of the opioid peptide activity isolated from brain and gut of several species by our method was due to methionine- and leucine-enkephalin. In contrast, the major opioid peptide activity recovered from the pituitary was due to peptides of much greater mol. wt. than the enkephalins. 3 An opioid peptide with properties unlike those of the known endorphins or enkephalins was present in brain extracts. This peptide, termed ε-endorphin, has an apparent mol. wt. of 700 to 1200; it constituted between 5 to 10% of the total opioid activity in our extracts. 4 A differential assay of methionine- and leucine-enkephalin was made either by destroying methionine-enkephalin activity with cyanogen bromide or by separating the peptides by thin layer chromatography. 5 The ratio of methionine-enkephalin to leucine-enkephalin varied greatly in different brain regions. The highest proportions of leucine-enkephalin were found in the cerebral cortex and hippocampus. 6 Formaldehyde perfusion and fixation of the brain in vivo had no significant effect on the brain content of enkephalin, indicating that proteolytic breakdown is not a major problem in the extraction of these peptides. 7 It is suggested that the enkephalins may have a neurotransmitter role in both brain and peripheral tissues and that methionine- and leucine-enkephalin may subserve separate neuronal functions. PMID:597668

  9. THE DISTRIBUTION OF METHIONINE-ENKEPHALIN AND LEUCINE-ENKEPHALIN IN THE BRAIN AND PERIPHERAL TISSUES

    PubMed Central

    Hughes, J; Kosterlitz, HW; Smith, TW

    1997-01-01

    A method is described for the rapid extraction of opioid peptides from the brain and other tissues. The method is based on acid extraction of tissues followed by adsorption of the extract onto Amberlite XAD-2 resin. Elution with methanol separates the enkephalins and α-endorphin from β-endorphin. Over 90% of the opioid peptide activity isolated from brain and gut of several species by our method was due to methionine- and leucine-enkephalin. In contrast, the major opioid peptide activity recovered from the pituitary was due to peptides of much greater mol. wt. than the enkephalins. An opioid peptide with properties unlike those of the known endorphins or enkephalins was present in brain extracts. This peptide, termed ∈-endorphin, has an apparent mol. wt. of 700 to 1200; it constituted between 5 to 10% of the total opioid activity in our extracts. A differential assay of methionine- and leucine-enkephalin was made either by destroying methionine-enkephalin activity with cyanogen bromide or by separating the peptides by thin layer chromatography. The ratio of methionine-enkephalin to leucine-enkephalin varied greatly in different brain regions. The highest proportions of leucine-enkephalin were found in the cerebral cortex and hippocampus. Formaldehyde perfusion and fixation of the brain in vivo had no significant effect on the brain content of enkephalin, indicating that proteolytic breakdown is not a major problem in the extraction of these peptides. It is suggested that the enkephalins may have a neurotransmitter role in both brain and peripheral tissues and that methionine- and leucine-enkephalin may subserve separate neuronal functions. PMID:9142421

  10. Crystal Structure of a Super Leucine Zipper an Extended Two-Stranded Super Long Coiled Coil

    SciTech Connect

    J Diao

    2011-12-31

    Coiled coil is a ubiquitous structural motif in proteins, with two to seven alpha helices coiled together like the strands of a rope, and coiled coil folding and assembly is not completely understood. A GCN4 leucine zipper mutant with four mutations of K3A, D7A, Y17W, and H18N has been designed, and the crystal structure has been determined at 1.6 {angstrom} resolution. The peptide monomer shows a helix trunk with short curved N- and C-termini. In the crystal, two monomers cross in 35{sup o} and form an X-shaped dimer, and each X-shaped dimer is welded into the next one through sticky hydrophobic ends, thus forming an extended two-stranded, parallel, super long coiled coil rather than a discrete, two-helix coiled coil of the wild-type GCN4 leucine zipper. Leucine residues appear at every seventh position in the super long coiled coil, suggesting that it is an extended super leucine zipper. Compared to the wild-type leucine zipper, the N-terminus of the mutant has a dramatic conformational change and the C-terminus has one more residue Glu 32 determined. The mutant X-shaped dimer has a large crossing angle of 35{sup o} instead of 18{sup o} in the wild-type dimer. The results show a novel assembly mode and oligomeric state of coiled coil, and demonstrate that mutations may affect folding and assembly of the overall coiled coil. Analysis of the formation mechanism of the super long coiled coil may help understand and design self-assembling protein fibers.

  11. Remote Sensing.

    ERIC Educational Resources Information Center

    Williams, Richard S., Jr.; Southworth, C. Scott

    1983-01-01

    The Landsat Program became the major event of 1982 in geological remote sensing with the successful launch of Landsat 4. Other 1982 remote sensing accomplishments, research, publications, (including a set of Landsat worldwide reference system index maps), and conferences are highlighted. (JN)

  12. Remote Sensing.

    ERIC Educational Resources Information Center

    Williams, Richard S., Jr.; Southworth, C. Scott

    1983-01-01

    The Landsat Program became the major event of 1982 in geological remote sensing with the successful launch of Landsat 4. Other 1982 remote sensing accomplishments, research, publications, (including a set of Landsat worldwide reference system index maps), and conferences are highlighted. (JN)

  13. Computational Analysis of the Hypothalamic Control of Food Intake

    PubMed Central

    Tabe-Bordbar, Shayan; Anastasio, Thomas J.

    2016-01-01

    Food-intake control is mediated by a heterogeneous network of different neural subtypes, distributed over various hypothalamic nuclei and other brain structures, in which each subtype can release more than one neurotransmitter or neurohormone. The complexity of the interactions of these subtypes poses a challenge to understanding their specific contributions to food-intake control, and apparent consistencies in the dataset can be contradicted by new findings. For example, the growing consensus that arcuate nucleus neurons expressing Agouti-related peptide (AgRP neurons) promote feeding, while those expressing pro-opiomelanocortin (POMC neurons) suppress feeding, is contradicted by findings that low AgRP neuron activity and high POMC neuron activity can be associated with high levels of food intake. Similarly, the growing consensus that GABAergic neurons in the lateral hypothalamus suppress feeding is contradicted by findings suggesting the opposite. Yet the complexity of the food-intake control network admits many different network behaviors. It is possible that anomalous associations between the responses of certain neural subtypes and feeding are actually consistent with known interactions, but their effect on feeding depends on the responses of the other neural subtypes in the network. We explored this possibility through computational analysis. We made a computer model of the interactions between the hypothalamic and other neural subtypes known to be involved in food-intake control, and optimized its parameters so that model behavior matched observed behavior over an extensive test battery. We then used specialized computational techniques to search the entire model state space, where each state represents a different configuration of the responses of the units (model neural subtypes) in the network. We found that the anomalous associations between the responses of certain hypothalamic neural subtypes and feeding are actually consistent with the known structure

  14. Effect of dehydration on hypothalamic control of evaporation in the cat.

    PubMed Central

    Baker, M A; Doris, P A

    1982-01-01

    1. Cats were surgically prepared with intracranial thermodes for heating of the hypothalamic thermosensitive area or with venous cannulae for measurement of blood volume and plasma osmolality. They were kept in an environmental chamber in which the ambient temperature was cycled between 25 and 38 degrees C on an 18:6 hr diurnal schedule. 2. Measurements of blood volume and plasma osmolality and of the evaporative response to hypothalamic heating were made during the 38 degrees C phase of the diurnal temperature cycle in animals when they were hydrated ad lib and in the same animals after 72--96 hr of water deprivation. 3. Water deprivation produced a loss of 10% of the body weight, a significant rise in plasma osmolality and a significant fall in blood volume. 4. Hypothalamic heating in hydrated animals generated a highly significant, positive, linear relationship between hypothalamic temperature and evaporative heat loss in every case. 5. In dehydrated animals, the evaporative response to hypothalamic heating was reduced. Rates of evaporation at a given hypothalamic temperature were lower and the slopes of the lines relating evaporative heat loss to hypothalamic temperature were significantly reduced. 6. It is concluded that dehydration reduces the thermal responsiveness of central neural structures controlling evaporation in the cat. PMID:7069627

  15. Hypothalamic Dysfunction and Multiple Sclerosis: Implications for Fatigue and Weight Dysregulation.

    PubMed

    Burfeind, Kevin G; Yadav, Vijayshree; Marks, Daniel L

    2016-11-01

    Signs and symptoms of multiple sclerosis are usually attributed to demyelinating lesions in the spinal cord or cerebral cortex. The hypothalamus is a region that is often overlooked yet controls many important homeostatic functions, including those that are perturbed in multiple sclerosis. In this review we discuss how hypothalamic dysfunction may contribute to signs and symptoms in people with multiple sclerosis. While dysfunction of the hypothalamic-pituitary-adrenal axis is common in multiple sclerosis, the effects and mechanisms of this dysfunction are not well understood. We discuss three hypothalamic mechanisms of fatigue in multiple sclerosis: (1) general hypothalamic-pituitary-adrenal axis hyperactivity, (2) disordered orexin neurotransmission, (3) abnormal cortisol secretion. We then review potential mechanisms of weight dysregulation caused by hypothalamic dysfunction. Lastly, we propose future studies and therapeutics to better understand and treat hypothalamic dysfunction in multiple sclerosis. Hypothalamic dysfunction appears to be common in multiple sclerosis, yet current studies are underpowered and contradictory. Future studies should contain larger sample sizes and standardize hormone and neuropeptide measurements.

  16. The hypothalamic GnRH pulse generator: multiple regulatory mechanisms.

    PubMed

    Krsmanovic, Lazar Z; Hu, Lian; Leung, Po-Ki; Feng, Hao; Catt, Kevin J

    2009-10-01

    Pulsatile secretion of gonadotropin-releasing hormone (GnRH) release is an intrinsic property of hypothalamic GnRH neurons. Pulse generation has been attributed to multiple specific mechanisms, including spontaneous electrical activity of GnRH neurons, calcium and cAMP signaling, a GnRH receptor autocrine regulatory component, a GnRH concentration-dependent switch in GnRH receptor (GnRH-R) coupling to specific G proteins, the expression of G protein-coupled receptors (GPCRs) and steroid receptors, and homologous and heterologous interactions between cell membrane receptors expressed in GnRH neurons. The coexistence of multiple regulatory mechanisms for pulsatile GnRH secretion provides a high degree of redundancy in maintaining this crucial component of the mammalian reproductive process. These studies provide insights into the basic cellular and molecular mechanisms involved in GnRH neuronal function.

  17. [Cortico-hypothalamic interneuronal correlation during learning in cats].

    PubMed

    Merzhanova, G Kh; Berg, A I

    1988-01-01

    Spatial-temporal organization of neuronal activity in the motor cortex and hypothalamus lateral nucleus (inter- and intrastructural neuronal interactions) in cats with elaborated conditioned alimentary instrumental reflexes were studied by means of recording the multineuronal activity of structures under investigation and with the use of cross-correlation method of analysis. An increase was shown of the number of cortico-hypothalamic neurones pairs acting in interconnection after elaboration of conditioned reflexes, and a decrease of their number at extinction due to interaction with temporal delays (up to 30 ms). Local (intrastructural) connections of the motor cortex and lateral hypothalamus had opposite dynamics at extinction of the conditioned reflexes: the number of the first increased and the number of the second decreased. The character of the interconnected activity of neurones pairs of interstructural interaction is discussed.

  18. Surgical management of hypothalamic hamartomas in patients with gelastic epilepsy.

    PubMed

    Addas, Bassam; Sherman, Elisabeth M S; Hader, Walter J

    2008-09-01

    Gelastic epilepsy (GE) associated with hypothalamic hamartomas (HHs) is now a well-characterized clinical syndrome consisting of gelastic seizures starting in infancy, medically refractory seizures with or without the development of multiple seizure types, and behavioral and cognitive decline. It has been postulated that the development of the HH-GE syndrome is a result of a progressive epileptic encephalopathy or secondary epileptogenesis, which is potentially reversible with treatment of the HH. A variety of surgical options for the treatment of HHs exist, including open and endoscopic procedures, radiosurgery, interstitial radiotherapy, and stereotactic radiofrequency thermocoagulation. Surgical treatment can result in seizure freedom in up to 50% of patients and can be accompanied by significant improvements in behavior, cognition, and quality of life. Partial treatment of HHs may be sufficient to reduce seizure frequency and improve behavior and quality of life with less risk. A component of reversible cognitive dysfunction may be present in some patients with an HH-GE syndrome.

  19. Hypothalamic CRH neurons orchestrate complex behaviours after stress

    PubMed Central

    Füzesi, Tamás; Daviu, Nuria; Wamsteeker Cusulin, Jaclyn I.; Bonin, Robert P.; Bains, Jaideep S.

    2016-01-01

    All organisms possess innate behavioural and physiological programmes that ensure survival. In order to have maximum adaptive benefit, these programmes must be sufficiently flexible to account for changes in the environment. Here we show that hypothalamic CRH neurons orchestrate an environmentally flexible repertoire of behaviours that emerge after acute stress in mice. Optical silencing of CRH neurons disrupts the organization of individual behaviours after acute stress. These behavioural patterns shift according to the environment after stress, but this environmental sensitivity is blunted by activation of PVN CRH neurons. These findings provide evidence that PVN CRH cells are part of a previously unexplored circuit that matches precise behavioural patterns to environmental context following stress. Overactivity in this network in the absence of stress may contribute to environmental ambivalence, resulting in context-inappropriate behavioural strategies. PMID:27306314

  20. Water intoxication death following hypothalamic lesions in the rat.

    PubMed

    Wishart, T B; Walls, E K

    1975-09-01

    Rats received large, bilateral lesions of the ventromedial hypothalamus. Water or saline intakes, urine outputs and body temperatures were observed for up to 24 hr after surgery. Fifty percent of the operated animals drank excessively and died within 4-6 hr when permitted access to water. Urine outputs were low and symptoms of water intoxication were evident. When allowed access to saline, outputs rose and the number of animals which survived increased as the saline concentration increased. Body temperatures approached 40 degrees C during drinking, but did not differ from operated animals which refused to drink. It was concluded that the deposition of metallic ions strongly stimulates a hypothalamic drinking system which results in overhydration and water intoxication death.

  1. Effects of neonatal programming on hypothalamic mechanisms controlling energy balance.

    PubMed

    Contreras, C; Novelle, M G; Leis, R; Diéguez, C; Skrede, S; López, M

    2013-12-01

    The prevalence of overweight and obesity in most developed countries has markedly increased during the last decades. In addition to genetic, hormonal, and metabolic influences, environmental factors like fetal and neonatal nutrition play key roles in the development of obesity. Interestingly, overweight during critical developmental periods of fetal and/or neonatal life has been demonstrated to increase the risk of obesity throughout juvenile life into adulthood. In spite of this evidence, the specific mechanisms underlying this fetal/neonatal programming are not perfectly understood. However, it is clear that circulating hormones such as insulin and leptin play a critical role in the development and programming of hypothalamic circuits regulating energy balance. Here, we review what is currently known about the impact of perinatal malnutrition on the mechanisms regulating body weight homeostasis. Understanding these molecular mechanisms may provide new targets for the treatment of obesity. © Georg Thieme Verlag KG Stuttgart · New York.

  2. Ventromedial hypothalamic neurons control a defensive emotion state.

    PubMed

    Kunwar, Prabhat S; Zelikowsky, Moriel; Remedios, Ryan; Cai, Haijiang; Yilmaz, Melis; Meister, Markus; Anderson, David J

    2015-03-06

    Defensive behaviors reflect underlying emotion states, such as fear. The hypothalamus plays a role in such behaviors, but prevailing textbook views depict it as an effector of upstream emotion centers, such as the amygdala, rather than as an emotion center itself. We used optogenetic manipulations to probe the function of a specific hypothalamic cell type that mediates innate defensive responses. These neurons are sufficient to drive multiple defensive actions, and required for defensive behaviors in diverse contexts. The behavioral consequences of activating these neurons, moreover, exhibit properties characteristic of emotion states in general, including scalability, (negative) valence, generalization and persistence. Importantly, these neurons can also condition learned defensive behavior, further refuting long-standing claims that the hypothalamus is unable to support emotional learning and therefore is not an emotion center. These data indicate that the hypothalamus plays an integral role to instantiate emotion states, and is not simply a passive effector of upstream emotion centers.

  3. The Hypothalamic Median Eminence and its Role in Reproductive Aging

    PubMed Central

    Yin, Weiling; Gore, Andrea C.

    2009-01-01

    The median eminence at the base of the hypothalamus serves as an interface between the neural and peripheral endocrine systems. It is the site where hypothalamic releasing hormones are released into the portal capillary bed to be transported to the anterior pituitary, which provides further signals to target endocrine systems. Of specific relevance to reproduction, a group of about 1000 neurons in mammals release the gonadotropin-releasing hormone (GnRH) peptide from neuroterminals in the median eminence. During the life cycle, there are dramatic changes in reproductive demands, and we focus this review on how GnRH terminals in the median eminence change during reproductive senescence. We discuss morphological and functional properties of the median eminence, and how relationships among GnRH terminals and their microenvironment of nerve terminals, glial cells, and the portal capillary vasculature determine the ability of GnRH peptide to be secreted and to reach its target in the anterior pituitary gland. PMID:20738281

  4. Leucine Deprivation Increases Hepatic Insulin Sensitivity via GCN2/mTOR/S6K1 and AMPK Pathways

    PubMed Central

    Xiao, Fei; Huang, Zhiying; Li, Houkai; Yu, Junjie; Wang, Chunxia; Chen, Shanghai; Meng, Qingshu; Cheng, Ying; Gao, Xiang; Li, Jia; Liu, Yong; Guo, Feifan

    2011-01-01

    OBJECTIVE We have previously shown that serum insulin levels decrease threefold and blood glucose levels remain normal in mice fed a leucine-deficient diet, suggesting increased insulin sensitivity. The goal of the current study is to investigate this possibility and elucidate the underlying cellular mechanisms. RESEARCH DESIGN AND METHODS Changes in metabolic parameters and expression of genes and proteins involved in regulation of insulin sensitivity were analyzed in mice, human HepG2 cells, and mouse primary hepatocytes under leucine deprivation. RESULTS We show that leucine deprivation improves hepatic insulin sensitivity by sequentially activating general control nonderepressible (GCN)2 and decreasing mammalian target of rapamycin/S6K1 signaling. In addition, we show that activation of AMP-activated protein kinase also contributes to leucine deprivation–increased hepatic insulin sensitivity. Finally, we show that leucine deprivation improves insulin sensitivity under insulin-resistant conditions. CONCLUSIONS This study describes mechanisms underlying increased hepatic insulin sensitivity under leucine deprivation. Furthermore, we demonstrate a novel function for GCN2 in the regulation of insulin sensitivity. These observations provide a rationale for short-term dietary restriction of leucine for the treatment of insulin resistance and associated metabolic diseases. PMID:21282364

  5. Neurokinin B and the Hypothalamic Regulation of Reproduction

    PubMed Central

    Rance, Naomi E.; Krajewski, Sally J.; Smith, Melinda A.; Cholanian, Marina; Dacks, Penny A.

    2010-01-01

    Loss of function mutations in the genes encoding either neurokinin B (NKB) or its receptor, NK3 (NK3R), result in hypogonadotropic hypogonadism, characterized by an absence of pubertal development and low circulating levels of LH and gonadal steroids. These studies implicate NKB and NK3R as essential elements of the human reproductive axis. Studies over the last two decades provide evidence that a group of neurons in the hypothalamic infundibular/arcuate nucleus form an important component of this regulatory circuit. These neurons are steroid-responsive and coexpress NKB, kisspeptin, dynorphin, NK3R and estrogen receptor α (ERα) in a variety of mammalian species. Compelling evidence in the human indicates these neurons function in the hypothalamic circuitry regulating estrogen negative feedback on gonadotropin-releasing hormone (GnRH) secretion. Moreover, in the rat, they form a bilateral, interconnected network that projects to NK3R-expressing GnRH terminals in the median eminence. This network provides an anatomical framework to explain how coordination among NKB/kisspeptin/dynorphin/NK3R/ERα neurons could mediate feedback information from the gonads to modulate pulsatile GnRH secretion. There is substantial (but indirect) evidence that this network may be part of the neural circuitry known as the “GnRH pulse generator”, with NK3R signaling as an important component. This theory provides a compelling explanation for the occurrence of hypogonadotropic hypogonadism in patients with inactivating mutations in the TAC3 orTACR3 genes. Future studies will be needed to determine whether NKB signaling plays a permissive role in the onset of puberty or is part of the driving force initiating the maturation of reproductive function. PMID:20800582

  6. Hypothalamic signaling in anorexia induced by indispensable amino acid deficiency

    PubMed Central

    Zhu, Xinxia; Krasnow, Stephanie M.; Roth-Carter, Quinn R.; Levasseur, Peter R.; Braun, Theodore P.; Grossberg, Aaron J.

    2012-01-01

    Animals exhibit a rapid and sustained anorexia when fed a diet that is deficient in a single indispensable amino acid (IAA). The chemosensor for IAA deficiency resides within the anterior piriform cortex (APC). Although the cellular and molecular mechanisms by which the APC detects IAA deficiency are well established, the efferent neural pathways that reduce feeding in response to an IAA-deficient diet remain to be fully characterized. In the present work, we investigated whether 1) central melanocortin signaling is involved in IAA deficiency-induced anorexia (IAADA) and 2) IAADA engages other key appetite-regulating neuronal populations in the hypothalamus. Rats and mice that consumed a valine-deficient diet (VDD) for 2–3 wk exhibited marked reductions in food intake, body weight, fat and lean body mass, body temperature, and white adipose tissue leptin gene expression, as well as a paradoxical increase in brown adipose tissue uncoupling protein-1 mRNA. Animals consuming the VDD had altered hypothalamic gene expression, typical of starvation. Pharmacological and genetic blockade of central melanocortin signaling failed to increase long-term food intake in this model. Chronic IAA deficiency was associated with a marked upregulation of corticotropin-releasing hormone expression in the lateral hypothalamus, particularly in the parasubthalamic nucleus, an area heavily innervated by efferent projections from the APC. Our observations indicate that the hypothalamic melanocortin system plays a minor role in acute, but not chronic, IAADA and suggest that the restraint on feeding is analogous to that observed after chronic dehydration. PMID:23047987

  7. Genetic, hypothalamic and endocrine features of clinical and experimental obesity.

    PubMed

    Bray, G A

    1992-01-01

    Obesity occurs in both clinical and animal forms in a variety of specific models which allow study of its underlining endocrine and mechanistic features. Among the neuroendocrine varieties of obesity, polycystic ovaries are probably the most common. The importance of the gonadal feedback system for regulation of food intake and obesity is indicated by the effects of castration in experimental animals which is a widely used mechanism for producing experimental obesity. Cushing syndrome and hypothalamic obesity are rare clinical syndromes. The current evidence suggests that there are two types of hypothalamic obesity from a mechanistic point of view--one associated with hyperphagia as a necessary and sufficient cause and a disturbance of the autonomic nervous system without hyperphagia as a second mechanism. Although genetic factors underlie most types of human obesity, there are several dymorphic forms of obesity including the Prader-Willy syndrome, Cohen's syndrome, Carpenter's syndrome, Ahlstrom's syndrome and the Bardet-Biedel syndrome. The Prader-Willi syndrome is characterized by obesity hypotonia hypogonadism and mental retardation. In animals, a dominant form of inheritance of obesity is seen in the yellow mouse. Current evidence suggests that this syndrome can be explained by reduced acetylation of MSH in the pituitary and/or hypothalamus. Several recessively inherited forms of obesity exist including the obese mouse, the diabetes mouse, fatty rat, the fat mouse, tubby mouse and the corpulent rat. In addition, there are a number of polygenic types of experimental obesity. The final mechanistic classification of obesity are those due to dietary manipulation. For both human beings and animals, a highly fat diet appears to be particularly problematic for the development of obesity.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. MRI-guided stereotactic radiofrequency thermocoagulation for 100 hypothalamic hamartomas.

    PubMed

    Kameyama, Shigeki; Shirozu, Hiroshi; Masuda, Hiroshi; Ito, Yosuke; Sonoda, Masaki; Akazawa, Kohei

    2016-05-01

    OBJECT The aim of this study was to elucidate the invasiveness, effectiveness, and feasibility of MRI-guided stereotactic radiofrequency thermocoagulation (SRT) for hypothalamic hamartoma (HH). METHODS The authors examined the clinical records of 100 consecutive patients (66 male and 34 female) with intractable gelastic seizures (GS) caused by HH, who underwent SRT as a sole surgical treatment between 1997 and 2013. The median duration of follow-up was 3 years (range 1-17 years). Seventy cases involved pediatric patients. Ninety percent of patients also had other types of seizures (non-GS). The maximum diameter of the HHs ranged from 5 to 80 mm (median 15 mm), and 15 of the tumors were giant HHs with a diameter of 30 mm or more. Comorbidities included precocious puberty (33.0%), behavioral disorder (49.0%), and mental retardation (50.0%). RESULTS A total of 140 SRT procedures were performed. There was no adaptive restriction for the giant or the subtype of HH, regardless of any prior history of surgical treatment or comorbidities. Patients in this case series exhibited delayed precocious puberty (9.0%), pituitary dysfunction (2.0%), and weight gain (7.0%), besides the transient hypothalamic symptoms after SRT. Freedom from GS was achieved in 86.0% of patients, freedom from other types of seizures in 78.9%, and freedom from all seizures in 71.0%. Repeat surgeries were not effective for non-GS. Seizure freedom led to disappearance of behavioral disorders and to intellectual improvement. CONCLUSIONS The present SRT procedure is a minimally invasive and highly effective surgical procedure without adaptive limitations. SRT involves only a single surgical procedure appropriate for all forms of epileptogenic HH and should be considered in patients with an early history of GS.

  9. The hypothalamic neuropeptide FF network is impaired in hypertensive patients

    PubMed Central

    Goncharuk, Valeri D; Buijs, Ruud M; Jhamandas, Jack H; Swaab, Dick F

    2014-01-01

    Background The human hypothalamus contains the neuropeptide FF (NPFF) neurochemical network. Animal experiments demonstrated that NPFF is implicated in the central cardiovascular regulation. We therefore studied expression of this peptide in the hypothalamus of individuals who suffered from essential hypertension (n = 8) and died suddenly due to acute myocardial infarction (AMI), and compared to that of healthy individuals (controls) (n = 6) who died abruptly due to mechanical trauma of the chest. Methods The frozen right part of the hypothalamus was cut coronally into serial sections of 20 μm thickness, and each tenth section was stained immunohistochemically using antibody against NPFF. The central section through each hypothalamic nucleus was characterized by the highest intensity of NPFF immunostaining and thus was chosen for quantitative densitometry. Results In hypertensive patients, the area occupied by NPFF immunostained neuronal elements in the central sections through the suprachiasmatic nucleus (SCh), paraventricular hypothalamic nucleus (Pa), bed nucleus of the stria terminalis (BST), perinuclear zone (PNZ) of the supraoptic nucleus (SON), dorso- (DMH), ventromedial (VMH) nuclei, and perifornical nucleus (PeF) was dramatically decreased compared to controls, ranging about six times less in the VMH to 15 times less in the central part of the BST (BSTC). The NPFF innervation of both nonstained neuronal profiles and microvasculature was extremely poor in hypertensive patients compared to control. Conclusions The decreased NPFF expression in the hypothalamus of hypertensive patients might be a cause of impairment of its interaction with other neurochemical systems, and thereby might be involved in the pathogenesis of the disease. PMID:25161813

  10. Hypoxia reduces the hypothalamic thermogenic threshold and thermosensitivity

    PubMed Central

    Tattersall, Glenn J; Milsom, William K

    2009-01-01

    Hypoxia is well known to reduce the body temperature (Tb) of mammals, although the neural origins of this response remain uncertain. Short-term hypoxic exposure causes a reduction in the lower critical temperature of the thermal neutral zone and a reduction in whole body thermal conductance of rodents, providing indirect support that hypoxia lowers Tb in a regulated manner. In this study, we examined directly the potential for changes in central thermosensitivity to evoke the hypoxic metabolic response by heating and cooling the preoptic area of the hypothalamus (the area which integrates thermoreceptor input and regulates thermoeffector outputs) using chronic, indwelling thermodes in ground squirrels during normoxia and hypoxia (7, 10 and 12% O2). We found that the threshold hypothalamic temperature for the metabolic response to cooling (Tth) of ∼38°C in normoxia was proportionately reduced in hypoxia (down to 28–31°C at 7% O2) and that the metabolic thermosensitivity (α; the change in metabolic rate for any given change in hypothalamic temperature below the lower critical temperature) was comparatively reduced by 5 to 9 times. This provides strong support for the hypothesis that the fall in temperature that occurs during hypoxia is the result of a reduction in the activation of thermogenic mechanisms. The decrease in the central thermosensitivity in hypoxia, however, appears to be a critical factor in the alteration of mammalian Tb. We suggest, therefore, that an altered central thermosensitivity may provide a proximate explanation of how low oxygen and similar stressors reduce normal fluctuations in Tb (i.e. circadian), in addition to the depression in regulated Tb. PMID:19770191

  11. Hypothalamic inflammation and energy homeostasis: resolving the paradox.

    PubMed

    Thaler, Joshua P; Choi, Sun Ju; Schwartz, Michael W; Wisse, Brent E

    2010-01-01

    Determining the effect of hypothalamic inflammatory signals on energy balance presents a paradox. On the one hand, a large body of work has identified inflammatory signaling in the hypothalamus as an essential mediator of the sickness response--the anorexia, cachexia, fever, inactivity, lethargy, anhedonia and adipsia that are triggered by systemic inflammatory stimuli and promote negative energy balance. On the other hand, numerous recent studies implicate inflammatory activation within the hypothalamus as a key factor whereby high-fat diets--and saturated fats in particular--cause central leptin and insulin resistance and thereby promote the defense of elevated body weight. This paradox will likely remain unresolved until several issues have been addressed. Firstly, the hypothalamus--unlike many peripheral inflamed tissues--is an extremely heterogeneous tissue comprised of astrocytes, oligodendrocytes, microglia, endothelial cells, ependymal cells as well as numerous neuronal subgroups. Determining exactly which cells activate defined inflammatory signals in response to a particular stimulus--i.e. sepsis vs. nutrient excess--may yield critical clues. Secondly, for the sake of simplicity many studies evaluate inflammation as an on/off phenomenon. More realistically, inflammatory signaling occurs as a cascade or cycle that changes and progresses over time. Accordingly, even within the same cell type, the low-grade, chronic signal induced by nutrient excess may invoke a different cascade of signals than a strong, acute signal such as sepsis. In addition, because tolerance can develop to certain inflammatory mediators, physiological outcomes may not correlate with early biochemical markers. Lastly, the neuroanatomical location, magnitude, and duration of the inflammatory stimulus can undoubtedly influence the net CNS response. Rigorously evaluating the progression of the inflammatory signaling cascade within specific hypothalamic cell types is a key next step towards

  12. Computer simulation of a neurosurgical operation: craniotomy for hypothalamic hamartoma.

    PubMed

    Sgouros, S; Natarajan, K; Walsh, A R; Rolfe, E B; Hockley, A D

    1998-07-01

    Although magnetic resonance imaging has revolutionised the management of intracranial lesions with improved visualisation of anatomical structures, it only produces two-dimensional images, from which the clinician has to extrapolate a three-dimensional interpretation. Several approaches can be used to create 3D images; the discipline of image segmentation has encompassed a number of these techniques. Such techniques allow the clinician to delineate areas of interest. The resulting computer-generated outlines can be reconstructed in a three-dimensional arrangement. Although a plethora of "generic" segmentation techniques exist, we have developed a refined form, dependent on general and particular properties of the anatomical structures under investigation. High-contrast structures such as the ventricles and external surface of the head are found by using a localised adaptive thresholding technique. Less definable structures, with poor or nonexistent signal change across neighbouring structures, such as brain stem or pituitary, are found by applying an "energy minimisation"-based technique. To demonstrate the techniques we used the example of an 8-year-old boy with uncontrolled gelastic seizures due to a hypothalamic hamartoma, who is being considered for surgery. We were able to demonstrate the anatomical relationships between the hypothalamic hamartoma and adjacent structures such as optic chiasm, brain stem and ventricular system. We were subsequently able to create a video, reproducing the stages of craniotomy for excision of this tumour. By creating true 3D objects, we were able at any stage of the simulation to visualise structures situated contralaterally to the approaching surgical dissector. These 3D representations of the structures can be either invisible or opaque, in order to afford 3D localisation as the "virtual" surgical dissection proceeds. The clinical application of such techniques will enable surgeons to improve their understanding of anatomical

  13. Nutritional programming affects hypothalamic organization and early response to leptin.

    PubMed

    Coupé, Bérengère; Amarger, Valérie; Grit, Isabelle; Benani, Alexandre; Parnet, Patricia

    2010-02-01

    Nutritional programming, taking place in utero or early after birth, is closely linked with metabolic and appetite disorders in adulthood. Following the hypothesis that nutritional programming impacts hypothalamic neuronal organization, we report on discrepancies of multiple molecular and cellular early events that take place in the hypothalamus of rats submitted to intrauterine growth restriction (IUGR). Expression screening performed on hypothalami from IUGR rats at birth and at postnatal d 12 identified changes in gene expression of neurodevelopmental process (cell differentiation and cytoskeleton organization). Additionally, a slight reduction of agouti-related protein and a strong reduction of alpha-MSH-immunoreactive efferent fibers were demonstrated in the paraventricular nucleus of IUGR rats. Rapid catch-up growth of IUGR rats, 5 d after birth, had a positive effect on neurodevelopmental factors and on neuronal projections emanating from the arcuate nucleus. The molecular and cellular anomalies detected in IUGR rats can be related to the reduced and delayed plasma leptin surge from d 0-16 when compared with control and IUGR rats with catch-up growth. However, the ability of leptin to activate intracellular signaling in arcuate nucleus neurons was not reduced in IUGR rats. Other mechanism such as epigenetic regulation of the major appetite-regulating neuropeptides genes was analyzed in parallel with their mRNA expression during postnatal development. This study reveals the importance of an early catch-up growth that reduces abnormal organization of hypothalamic pathways involved in energy homeostasis, whereas protein restriction, maintained during postnatal development leads to an important immaturity of the hypothalamus.

  14. Regulation of the hypothalamic-pituitary-adrenocortical stress response

    PubMed Central

    Herman, James P.; McKlveen, Jessica M.; Ghosal, Sriparna; Kopp, Brittany; Wulsin, Aynara; Makinson, Ryan; Scheimann, Jessie; Myers, Brent

    2016-01-01

    The hypothalamo-pituitary-adrenocortical (HPA axis) is required for stress adaptation. Activation of the HPA axis causes secretion of glucocorticoids, which act on multiple organ systems to redirect energy resources to meet real or anticipated demand. The HPA stress response is driven primarily by neural mechanisms, invoking corticotrophin releasing hormone (CRH) release from hypothalamic paraventricular nucleus (PVN) neurons. Pathways activating CRH release are stressor dependent: reactive responses to homeostatic disruption frequently involve direct noradrenergic or peptidergic drive of PVN neurons by sensory relays, whereas anticipatory responses use oligosynaptic pathways originating in upstream limbic structures. Anticipatory responses are driven largely by disinhibition, mediated by trans-synaptic silencing of tonic PVN inhibition via GABAergic neurons in the amygdala. Stress responses are inhibited by negative feedback mechanisms, whereby glucocorticoids act to diminish drive (brainstem), promote trans-synaptic inhibition by limbic structures (e.g, hippocampus). Glucocorticoids also act at the PVN to rapidly inhibit CRH neuronal activity via membrane glucocorticoid receptors. Chronic stress-induced activation of the HPA axis takes many forms (chronic basal hypersecretion, sensitized stress responses, even adrenal exhaustion), with manifestation dependent upon factors such as stressor chronicity, intensity, frequency and modality. Neural mechanisms driving chronic stress responses can be distinct from those controlling acute reactions, including recruitment of novel limbic, hypothalamic and brainstem circuits. Importantly, an individual’s response to acute or chronic stress is determined by numerous factors, including genetics, early life experience, environmental conditions, sex and age. The context in which stressors occur will determine whether an individual’s acute or chronic stress responses are adaptive or maladaptive (pathological). PMID:27065163

  15. Hypothalamic CB1 cannabinoid receptors regulate energy balance in mice.

    PubMed

    Cardinal, Pierre; Bellocchio, Luigi; Clark, Samantha; Cannich, Astrid; Klugmann, Matthias; Lutz, Beat; Marsicano, Giovanni; Cota, Daniela

    2012-09-01

    Cannabinoid type 1 (CB(1)) receptor activation is generally considered a powerful orexigenic signal and inhibition of the endocannabinoid system is beneficial for the treatment of obesity and related metabolic diseases. The hypothalamus plays a critical role in regulating energy balance by modulating both food intake and energy expenditure. Although CB(1) receptor signaling has been implicated in the modulation of both these mechanisms, a complete understanding of its role in the hypothalamus is still lacking. Here we combined a genetic approach with the use of adeno-associated viral vectors to delete the CB(1) receptor gene in the adult mouse hypothalamus and assessed the impact of such manipulation on the regulation of energy balance. Viral-mediated deletion of the CB(1) receptor gene in the hypothalamus led to the generation of Hyp-CB(1)-KO mice, which displayed an approximately 60% decrease in hypothalamic CB(1) receptor mRNA levels. Hyp-CB(1)-KO mice maintained on a normocaloric, standard diet showed decreased body weight gain over time, which was associated with increased energy expenditure and elevated β(3)-adrenergic receptor and uncoupling protein-1 mRNA levels in the brown adipose tissue but, surprisingly, not to changes in food intake. Additionally, Hyp-CB(1)-KO mice were insensitive to the anorectic action of the hormone leptin (5 mg/kg) and displayed a time-dependent hypophagic response to the CB(1) inverse agonist rimonabant (3 mg/kg). Altogether these findings suggest that hypothalamic CB(1) receptor signaling is a key determinant of energy expenditure under basal conditions and reveal its specific role in conveying the effects of leptin and pharmacological CB1 receptor antagonism on food intake.

  16. Thiamine deficiency induces anorexia by inhibiting hypothalamic AMPK.

    PubMed

    Liu, M; Alimov, A P; Wang, H; Frank, J A; Katz, W; Xu, M; Ke, Z-J; Luo, J

    2014-05-16

    Obesity and eating disorders are prevailing health concerns worldwide. It is important to understand the regulation of food intake and energy metabolism. Thiamine (vitamin B1) is an essential nutrient. Thiamine deficiency (TD) can cause a number of disorders in humans, such as Beriberi and Wernicke-Korsakoff syndrome. We demonstrated here that TD caused anorexia in C57BL/6 mice. After feeding a TD diet for 16days, the mice displayed a significant decrease in food intake and an increase in resting energy expenditure (REE), which resulted in a severe weight loss. At the 22nd day, the food intake was reduced by 69% and 74% for male and female mice, respectively in TD group. The REE increased by ninefolds in TD group. The loss of body weight (17-24%) was similar between male and female animals and mainly resulted from the reduction of fat mass (49% decrease). Re-supplementation of thiamine (benfotiamine) restored animal's appetite, leading to a total recovery of body weight. The hypothalamic adenosine monophosphate-activated protein kinase (AMPK) is a critical regulator of food intake. TD inhibited the phosphorylation of AMPK in the arcuate nucleus (ARN) and paraventricular nucleus (PVN) of the hypothalamus without affecting its expression. TD-induced inhibition of AMPK phosphorylation was reversed once thiamine was re-supplemented. In contrast, TD increased AMPK phosphorylation in the skeletal muscle and upregulated the uncoupling protein (UCP)-1 in brown adipose tissues which was consistent with increased basal energy expenditure. Re-administration of thiamine stabilized AMPK phosphorylation in the skeletal muscle as well as energy expenditure. Taken together, TD may induce anorexia by inhibiting hypothalamic AMPK activity. With a simultaneous increase in energy expenditure, TD caused an overall body weight loss. The results suggest that the status of thiamine levels in the body may affect food intake and body weight.

  17. Effects of taurine, homotaurine and GABA on hypothalamic and striatal dopamine metabolism.

    PubMed

    Panula-Lehto, E; Mäkinen, M; Ahtee, L

    1992-07-01

    To elucidate the effects of taurine on hypothalamic and striatal dopaminergic neurotransmission we compared its effects to those of gamma-aminobutyric acid (GABA) and homotaurine (a GABAA-receptor agonist) on hypothalamic and striatal concentrations of dopamine (DA) and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and, in the case of striatum, 3-methoxytyramine (3-MT) in rats. In addition, hypothalamic and striatal 5-hydroxytryptamine (5-HT) und 5-hydroxyindoleacetic acid, hypothalamic noradrenaline (NA) and 3-methoxy-4-hydroxyphenylglycol sulfate, and pituitary DA concentrations were also measured. The amino acids were injected into the lateral brain ventricles of conscious male rats in doses of 10 and 36 mumol/rat, and rat were sacrificed 15 and 60 min later, respectively. Homotaurine (by 11%) but not the other two amino acids elevated striatal DA, whereas hypothalamic DA was increased by both taurine (36%) and homotaurine (31%). All three amino acids at 36 mumol elevated striatal DOPAC, homotaurine (51%) more than taurine (31%) or GABA (30%), and hypothalamic DOPAC, both taurine (102%) and homotaurine (82%) clearly more than GABA (34%). Neither striatal nor hypothalamic HVA was altered by any of the amino acids. At 10 mumol the amino acids decreased striatal 3-MT by about 40%. At 36 mumol taurine and homotaurine reduced 3-MT by about 70%, whereas increasing the dose of GABA did not further reduce 3-MT. Both taurine and homotaurine at 36 mumol decreased hypothalamic NA content. Neither hypothalamic nor striatal 5-HT metabolism was altered. In the neurointermediate lobe of the pituitary gland taurine at 10 mumol but not at 36 mumol slightly (20%) increased DA.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Chronic leucine exposure results in reduced but reversible glucose-stimulated insulin secretion in INS-1 cells.

    PubMed

    Zhang, Xiujuan; Han, Wenxia; Jiang, Xiuyun; Li, Min; Gao, Ling; Zhao, Jia Jun

    2014-06-01

    Previous studies have demonstrated that sustained high leucine exposure decreases glucose-stimulated insulin secretion (GSIS). However, whether this effect is recoverable following the removal of leucine is unclear. Pancreatic/duodenal homeobox-1 (PDX-1) and its downstream target, glucose transporter 2 (GLUT2), are reported to be positively associated with insulin secretion. However, it also remains unclear whether the effect of leucine on GSIS is accompanied by alterations in PDX-1 and GLUT2. In the present study, insulin secretion, insulin content, PDX-1 and GLUT2 protein expression in INS-1 (rat insulinoma cell line) cells were assessed following a 24-h incubation in 40 mmol/l leucine. Half of the cells were incubated in leucine-free media for a further 24 h to observe the abovementioned effects. In contrast to the control, 40 mmol/l leucine for 24 or 48 h diminished GSIS at high glucose concentrations by 11% (P=0.026) or 22% (P=0.003), insulin content by 14% (P=0.008) or 20% (P=0.002), as well as decreasing PDX-1 and GLUT2 expression. When leucine was removed from the media for a further 24-h incubation, in comparison with those cells that were maintained in leucine treatment for 24 and 48 h, the high GSIS increased by 13% (P=0.032) and 27% (P=0.002), insulin content was augmented by 10% (P=0.014) and 20% (P=0.003), and the protein expression of PDX-1 and GLUT2 also increased. The present study demonstrates that sustained high concentrations of leucine induce a reversible impairment of GSIS and alter insulin content, which is mediated by PDX-1 and GLUT2, in INS-1 cells.

  19. Leptin and leucine synergistically regulate protein metabolism in C2C12 myotubes and mouse skeletal muscles.

    PubMed

    Mao, Xiangbing; Zeng, Xiangfang; Huang, Zhimin; Wang, Junjun; Qiao, Shiyan

    2013-07-28

    Leucine and leptin play important roles in regulating protein synthesis and degradation in skeletal muscles in vitro and in vivo. However, the objective of the present study was to determine whether leptin and leucine function synergistically in regulating protein metabolism of skeletal muscles. In the in vitro experiment, C2C12 myotubes were cultured for 2 h in the presence of 5 mm-leucine and/or 50 ng/ml of leptin. In the in vivo experiment, C57BL/6 and ob/ob mice were randomly assigned to be fed a non-purified diet supplemented with 3 % L-leucine or 2·04 % L-alanine (isonitrogenous control) for 14 d. Ob/ob mice were injected intraperitoneally with sterile PBS or recombinant mouse leptin (0·1 μg/g body weight) for 14 d. In C57BL/6 mice, dietary leucine supplementation increased (P< 0·05) plasma leptin, leptin receptor expression and protein synthesis in skeletal muscles, but reduced (P< 0·05) plasma urea and protein degradation in skeletal muscles. Dietary leucine supplementation and leptin injection increased the relative weight of the gastrocnemius and soleus muscles in ob/ob mice. Moreover, leucine and leptin treatments stimulated (P< 0·05) protein synthesis and inhibited (P< 0·05) protein degradation in C2C12 myotubes and skeletal muscles of ob/ob mice. There were interactions (P< 0·05) between the leucine and leptin treatments with regard to protein metabolism in C2C12 myotubes and soleus muscles of ob/ob mice but not in the gastrocnemius muscles of ob/ob mice. Collectively, these results suggest that leptin and leucine synergistically regulate protein metabolism in skeletal muscles both in vitro and in vivo.

  20. Hypothalamic obesity syndrome: rare presentation of CNS+ B-cell lymphoblastic lymphoma.

    PubMed

    Quigg, Troy C; Haddad, Nadine G; Buchsbaum, Jeffrey C; Shih, Chie-Schin

    2012-11-01

    Hypothalamic obesity syndrome can affect brain tumor patients following surgical intervention and irradiation. This syndrome is rare at diagnosis in childhood cancer, but has been reported with relapse of acute lymphoblastic leukemia. Here we present a case of hypothalamic obesity syndrome as the primary presentation of a toddler found to have CNS+ B-cell lymphoblastic lymphoma. Cytogenetic studies on diagnostic cerebrospinal fluid revealed MLL gene rearrangement (11q23). Hyperphagia and obesity dramatically improved following induction and consolidation chemotherapy. We describe a novel presentation of hypothalamic obesity syndrome in CNS B-cell lymphoblastic lymphoma, responsive to chemotherapy. Copyright © 2011 Wiley Periodicals, Inc.

  1. Gelastic seizures and low-grade hypothalamic astrocytoma: a case report.

    PubMed

    Coppola, Giangennaro; Spagnoli, Diego; Sciscio, Nicola; Russo, Francesco; Villani, Roberto Matteo

    2002-04-01

    The typical, well recognized childhood epilepsy syndrome caused by hypothalamic hamartoma is characterized by early-onset, stereotyped attacks of uncontrollable laughter, frequent refractory seizures with progressive cognitive deterioration and severe behavioral problems. Here, we report a 17-year-old patient with gelastic phenomenon started in the neonatal period, later on associated with drug resistant polymorphic seizures, intellectual deficit and behavioral disorders, who improved by partial resection of an expected hypothalamic