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Sample records for hypothalamic leucine sensing

  1. 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

  2. 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

  3. Ghrelin modulates hypothalamic fatty acid-sensing and control of food intake in rainbow trout.

    PubMed

    Velasco, Cristina; Librán-Pérez, Marta; Otero-Rodiño, Cristina; López-Patiño, Marcos A; Míguez, Jesús M; Cerdá-Reverter, José Miguel; Soengas, José L

    2016-01-01

    There is no information available on fish as far as the possible effects of ghrelin on hypothalamic fatty acid metabolism and the response of fatty acid-sensing systems, which are involved in the control of food intake. Therefore, we assessed in rainbow trout the response of food intake, hypothalamic fatty acid-sensing mechanisms and expression of neuropeptides involved in the control of food intake to the central treatment of ghrelin in the presence or absence of a long-chain fatty acid such as oleate. We observed that the orexigenic actions of ghrelin in rainbow trout are associated with changes in fatty acid metabolism in the hypothalamus and an inhibition of fatty acid-sensing mechanisms, which ultimately lead to changes in the expression of anorexigenic and orexigenic peptides resulting in increased orexigenic potential and food intake. Moreover, the response to increased levels of oleate of hypothalamic fatty acid-sensing systems (activation), expression of neuropeptides (enhanced anorexigenic potential) and food intake (decrease) were counteracted by the simultaneous treatment with ghrelin. These changes provide evidence for the first time in fish of a possible modulatory role of ghrelin on the metabolic regulation by fatty acid of food intake occurring in the hypothalamus. PMID:26459641

  4. Co-localization of hypocretin-1 and leucine-enkephalin in hypothalamic neurons projecting to the nucleus of the solitary tract and their effect on arterial pressure.

    PubMed

    Ciriello, J; Caverson, M M; McMurray, J C; Bruckschwaiger, E B

    2013-10-10

    Experiments were done to investigate whether hypothalamic hypocretin-1 (hcrt-1; orexin-A) neurons that sent axonal projections to cardiovascular responsive sites in the nucleus of the solitary tract (NTS) co-expressed leucine-enkephalin (L-Enk), and to determine the effects of co-administration of hcrt-1 and D-Ala2,D-Leu5-Enkephalin (DADL) into NTS on mean arterial pressure (MAP) and heart rate. In the first series, in the Wistar rat the retrograde tract-tracer fluorogold (FG) was microinjected (50nl) into caudal NTS sites at which L-glutamate (0.25 M; 10 nl) elicited decreases in MAP and where fibers hcrt-1 immunoreactive fibers were observed that also contained L-Enk immunoreactivity. Of the number of hypothalamic hcrt-1 immunoreactive neurons identified ipsilateral to the NTS injection site (1207 ± 78), 32.3 ± 2.3% co-expressed L-Enk immunoreactivity and of these, 2.6 ± 1.1% were retrogradely labeled with FG. Hcrt-1/L-Enk neurons projecting to NTS were found mainly within the perifornical region. In the second series, the region of caudal NTS found to contain axons that co-expressed hcrt-1 and L-Enk immunoreactivity was microinjected with a combination of hcrt-1 and DADL in α-chloralose anesthetized Wistar rats. Microinjection of DADL into NTS elicited depressor and bradycardia responses similar to those elicited by microinjection of hcrt-1. An hcrt-1 injection immediately after the DADL injection elicited an almost twofold increase in the magnitude of the depressor and bradycardia responses compared to those elicited by hcrt-1 alone. Prior injections of the non-specific opioid receptor antagonist naloxone or the specific opioid δ-receptor antagonist ICI 154,129 significantly attenuated the cardiovascular responses to the combined hcrt-1-DADL injections. Taken together, these data suggest that activation of hypothalamic-opioidergic neuronal systems contribute to the NTS hcrt-1 induced cardiovascular responses, and that this descending hypothalamo

  5. Sodium coupled glucose co-transporters contribute to hypothalamic glucose-sensing

    PubMed Central

    O'Malley, Dervla; Reimann, Frank; Simpson, Anna K; Gribble, Fiona M

    2007-01-01

    Specialised neurons within the hypothalamus have the ability to sense and respond to changes in ambient glucose concentrations. We investigated the mechanisms underlying glucose-triggered activity in glucose-excited (GE) neurons, using primary cultures of rat hypothalamic neurons monitored by fluorescence calcium imaging. 35% (738/2139) of neurons were excited by increasing glucose from 3 to 15mM, but only 9% (6/64) of these GE neurons were activated by tolbutamide, suggesting the involvement of a KATP channel-independent mechanism. α-Methylglucopyranoside (αMDG, 12mM), a non-metabolisable substrate of sodium glucose co-transporters (SGLTs), mimicked the effect of high glucose in 67% of GE neurons, and both glucose and αMDG-triggered excitation were blocked by Na+ removal or by the SGLT inhibitor, phloridzin (100nM). In the presence of 0.5mM glucose and tolbutamide, responses could also be triggered by 3.5mM αMDG, supporting a role for an SGLT-associated mechanism at low as well as high substrate concentrations. By RT-PCR, we detected SGLT1, SGLT3a, SGLT3b in both cultured neurons and adult rat hypothalamus. Our findings suggest a novel role for SGLTs in glucose-sensing by hypothalamic GE neurons. PMID:17130483

  6. 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. PMID:27083123

  7. 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

  8. F-box and Leucine-rich Repeat Protein 5 (FBXL5): sensing intracellular iron and oxygen

    PubMed Central

    Ruiz, Julio C.; Bruick, Richard K.

    2014-01-01

    Though essential for many vital biological processes, excess iron results in the formation of damaging reactive oxygen species (ROS). Therefore, iron metabolism must be tightly regulated. F-box and leucine-rich repeat protein 5 (FBXL5), an E3 ubiquitin ligase subunit, regulates cellular and systemic iron homeostasis by facilitating iron regulatory protein 2 (IRP2) degradation. FBXL5 possesses an N-terminal hemerythrin (Hr)-like domain that mediates its own differential stability by switching between two different conformations to communicate cellular iron availability. In addition, the FBXL5-Hr domain also senses O2 availability, albeit by a distinct mechanism. Mice lacking FBXL5 fail to sense intracellular iron levels and die in utero due to iron overload and exposure to damaging levels of oxidative stress. By closely monitoring intracellular levels of iron and oxygen, FBLX5 prevents the formation of conditions that favor ROS formation. These findings suggest that FBXL5 is essential for the maintenance of iron homeostasis and is a key sensor of bioavailable iron. Here, we describe the iron and oxygen sensing mechanisms of the FBXL5 Hr-like domain and its role in mediating ROS biology. PMID:24508277

  9. F-box and leucine-rich repeat protein 5 (FBXL5): sensing intracellular iron and oxygen.

    PubMed

    Ruiz, Julio C; Bruick, Richard K

    2014-04-01

    Though essential for many vital biological processes, excess iron results in the formation of damaging reactive oxygen species (ROS). Therefore, iron metabolism must be tightly regulated. F-box and leucine-rich repeat protein 5 (FBXL5), an E3 ubiquitin ligase subunit, regulates cellular and systemic iron homeostasis by facilitating iron regulatory protein 2 (IRP2) degradation. FBXL5 possesses an N-terminal hemerythrin (Hr)-like domain that mediates its own differential stability by switching between two different conformations to communicate cellular iron availability. In addition, the FBXL5-Hr domain also senses O2 availability, albeit by a distinct mechanism. Mice lacking FBXL5 fail to sense intracellular iron levels and die in utero due to iron overload and exposure to damaging levels of oxidative stress. By closely monitoring intracellular levels of iron and oxygen, FBLX5 prevents the formation of conditions that favor ROS formation. These findings suggest that FBXL5 is essential for the maintenance of iron homeostasis and is a key sensor of bioavailable iron. Here, we describe the iron and oxygen sensing mechanisms of the FBXL5 Hr-like domain and its role in mediating ROS biology. PMID:24508277

  10. 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

  11. 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. PMID:26468264

  12. Hypothalamic neurogenesis persists in the aging brain and is controlled by energy-sensing IGF-I pathway.

    PubMed

    Chaker, Zayna; George, Caroline; Petrovska, Marija; Caron, Jean-Baptiste; Lacube, Philippe; Caillé, Isabelle; Holzenberger, Martin

    2016-05-01

    Hypothalamic tanycytes are specialized glial cells lining the third ventricle. They are recently identified as adult stem and/or progenitor cells, able to self-renew and give rise to new neurons postnatally. However, the long-term neurogenic potential of tanycytes and the pathways regulating lifelong cell replacement in the adult hypothalamus are largely unexplored. Using inducible nestin-CreER(T2) for conditional mutagenesis, we performed lineage tracing of adult hypothalamic stem and/or progenitor cells (HySC) and demonstrated that new neurons continue to be born throughout adult life. This neurogenesis was targeted to numerous hypothalamic nuclei and produced different types of neurons in the dorsal periventricular regions. Some adult-born neurons integrated the median eminence and arcuate nucleus during aging and produced growth hormone releasing hormone. We showed that adult hypothalamic neurogenesis was tightly controlled by insulin-like growth factors (IGF). Knockout of IGF-1 receptor from hypothalamic stem and/or progenitor cells increased neuronal production and enhanced α-tanycyte self-renewal, preserving this stem cell-like population from age-related attrition. Our data indicate that adult hypothalamus retains the capacity of cell renewal, and thus, a substantial degree of structural plasticity throughout lifespan. PMID:27103519

  13. Leucine aminopeptidase blood test

    MedlinePlus

    Serum leucine aminopeptidase ... Leucine aminopeptidase is a type of protein called an enzyme . This enzyme is normally found in cells ... check if your liver is damaged. Too much leucine aminopeptidase is released into your blood when you ...

  14. Leucine aminopeptidase - urine

    MedlinePlus

    Leucine aminopeptidase is a type of protein called an enzyme. It is normally found in liver cells ... Increased levels of leucine aminopeptidase can be seen in ... Hepatitis Liver cancer Liver ischemia (reduced blood flow to the ...

  15. Leucine aminopeptidase - urine

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003617.htm Leucine aminopeptidase - urine To use the sharing features on this page, please enable JavaScript. Leucine aminopeptidase is a type of protein called an ...

  16. 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.

  17. Structural and molecular characterization of iron-sensing hemerythrin-like domain within F-box and leucine-rich repeat protein 5 (FBXL5).

    PubMed

    Thompson, Joel W; Salahudeen, Ameen A; Chollangi, Srinivas; Ruiz, Julio C; Brautigam, Chad A; Makris, Thomas M; Lipscomb, John D; Tomchick, Diana R; Bruick, Richard K

    2012-03-01

    Mammalian cells maintain iron homeostasis by sensing changes in bioavailable iron levels and promoting adaptive responses. FBXL5 is a subunit of an E3 ubiquitin ligase complex that mediates the stability of iron regulatory protein 2, an important posttranscriptional regulator of several genes involved in iron metabolism. The stability of FBXL5 is regulated in an iron- and oxygen-responsive manner, contingent upon the presence of its N-terminal domain. Here we present the atomic structure of the FBXL5 N terminus, a hemerythrin-like α-helical bundle fold not previously observed in mammalian proteins. The core of this domain employs an unusual assortment of amino acids necessary for the assembly and sensing properties of its diiron center. These regulatory features govern the accessibility of a mapped sequence required for proteasomal degradation of FBXL5. Detailed molecular and structural characterization of the ligand-responsive hemerythrin domain provides insights into the mechanisms by which FBXL5 serves as a unique mammalian metabolic sensor. PMID:22253436

  18. Structural and Molecular Characterization of Iron-sensing Hemerythrin-like Domain within F-box and Leucine-rich Repeat Protein 5 (FBXL5)♦

    PubMed Central

    Thompson, Joel W.; Salahudeen, Ameen A.; Chollangi, Srinivas; Ruiz, Julio C.; Brautigam, Chad A.; Makris, Thomas M.; Lipscomb, John D.; Tomchick, Diana R.; Bruick, Richard K.

    2012-01-01

    Mammalian cells maintain iron homeostasis by sensing changes in bioavailable iron levels and promoting adaptive responses. FBXL5 is a subunit of an E3 ubiquitin ligase complex that mediates the stability of iron regulatory protein 2, an important posttranscriptional regulator of several genes involved in iron metabolism. The stability of FBXL5 is regulated in an iron- and oxygen-responsive manner, contingent upon the presence of its N-terminal domain. Here we present the atomic structure of the FBXL5 N terminus, a hemerythrin-like α-helical bundle fold not previously observed in mammalian proteins. The core of this domain employs an unusual assortment of amino acids necessary for the assembly and sensing properties of its diiron center. These regulatory features govern the accessibility of a mapped sequence required for proteasomal degradation of FBXL5. Detailed molecular and structural characterization of the ligand-responsive hemerythrin domain provides insights into the mechanisms by which FBXL5 serves as a unique mammalian metabolic sensor. PMID:22253436

  19. The role of tanycytes in hypothalamic glucosensing.

    PubMed

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

    2015-07-01

    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

  20. 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

  1. 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

  2. Pubertas praecox and hypothalamic hamartoma.

    PubMed

    Takeuchi, J; Handa, H

    1985-01-01

    Precocious puberty of cerebral origin is classified into pseudoprecocious puberty and true precocious puberty. Pseudoprecocious puberty is caused by HCG secreting tumours. True precocious puberty is caused by various hypothalamic diseases. Among them, hypothalamic hamartoma is the most common cause. Precocious puberty is caused by elevated blood pituitary gonadotropin concentration, secondary to the elevated hypothalamic LHRH secretion. The hypothalamic hamartoma is not infrequently associated with laughing (gelastic) seizures as well as convulsions. Diagnosis of a hypothalamic hamartoma is easily made by CT. Although the hypothalamic hamartoma is difficult to operate on, the value of surgery is stressed for treatment of precocious puberty. This is also confirmed by recent reports. PMID:3897897

  3. Leucine metabolism in stable cirrhosis.

    PubMed

    Mullen, K D; Denne, S C; McCullough, A J; Savin, S M; Bruno, D; Tavill, A S; Kalhan, S C

    1986-01-01

    Alterations in protein and amino acid metabolism have been postulated to explain the frequent observations of muscle wasting and decreased plasma branched-chain amino acid concentrations in cirrhosis. In order to investigate the changes in protein metabolism, we have measured the rates of leucine turnover and oxidation in six stable, biopsy-proven cirrhotics and six age and sex-matched healthy control subjects after an overnight fast, using [1-13C]leucine tracer. Following a primed constant-rate infusion of [1-13C]leucine, the 13C enrichments of plasma leucine and expired CO2 were used to estimate leucine turnover and oxidation, respectively. Fat-free body mass was estimated from the measurements of total body water as quantified by H2[18O] tracer dilution. The rates of CO2 production and oxygen consumption were measured hourly during the study period, using open-circuit respiratory calorimetry. Urinary urea, ammonia and total nitrogen excretion rates were quantified from timed urine samples. Even though the plasma leucine levels were lower in cirrhotics as compared with controls (100.5 +/- 17.1 vs. 138.3 +/- 20.4 mumoles per liter, mean +/- S.D., p less than 0.001), the rates of leucine turnover were not significantly different in the two groups (89.4 +/- 19.0 vs. 87.8 +/- 19.0 mumoles per kg X hr). In contrast, the rates of leucine oxidation were significantly reduced in cirrhosis (8.1 +/- 2.5 vs. 12.7 +/- 3.1 mumoles per kg X hr, p less than 0.01). When all subjects were considered, the leucine oxidation rate was correlated with plasma leucine concentration (r = 0.62, p less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3089896

  4. Leucine improves glucose and lipid status in offspring from obese dams, dependent on diet type, but not caloric intake.

    PubMed

    Chen, H; Simar, D; Ting, J H Y; Erkelens, J R S; Morris, M J

    2012-10-01

    Previously, we showed that offspring from obese rat dams were hyperphagic, with increased adiposity, hyperlipidaemia and glucose intolerance associated with increased orexigenic neuropeptide expression after fasting. Mammalian target of rapamycin (mTOR) can inhibit food intake through a hypothalamic action. As we previously showed that maternal obesity down-regulated hypothalamic mTOR, in the present study, we hypothesised that dietary leucine supplementation would activate hypothalamic mTOR to reduce food intake, thus limiting metabolic disorders in offspring from obese dams, regardless of postweaning diet. Obesity was induced in Sprague-Dawley females by high-fat diet (HFD) for 5 weeks before mating, throughout gestation and lactation. Male pups from HFD-fed mothers were weaned onto chow or HFD; within each dietary group, half were supplied with leucine via drinking water (1.5%) versus water control for 10 weeks. Those from chow-fed mothers were fed chow and water. Maternal obesity led to increased adiposity in chow-fed offspring. Postweaning HFD consumption exaggerated adiposity, hyperglycaemia, hyperinsulinaemia and hyperlipidaemia. Supplementation with leucine doubled leucine intake and increased hypothalamic mTOR activation; however, appetite regulation was not affected. A reduction in blood lipid levels was observed in offspring regardless of diet, as well as improved glucose tolerance in HFD-fed rats. In HFD-fed rats, up-regulated carnitine palmitoyl-transferase-1 and peroxisome-proliferator-activated receptor-γ coactivator-1α in muscle and glucose transporter 4 in fat suggested that leucine improved peripheral fat oxidation and glucose transport. Leucine is able to improve peripheral glucose and lipid metabolism independent of appetite and weight regulation, suggesting its potential application in the management of metabolic disorders. PMID:22612562

  5. Direct innervation of GnRH neurons by metabolic- & sexual odorant-sensing leptin receptor neurons in the hypothalamic ventral premammillary nucleus

    PubMed Central

    Leshan, Rebecca L.; Louis, Gwendolyn W.; Jo, Young-Hwan; Rhodes, Christopher J.; Münzberg, Heike; Myers, Martin G.

    2009-01-01

    Leptin acts via its receptor (LepRb) on specific CNS neurons to signal the adequacy of long-term energy stores, thereby permitting the expenditure of resources on energy-intensive processes such as reproduction. The ventral premammillary nucleus of the hypothalamus (PMv), which has been implicated in the stimulation of gonadotropin release by olfactory cues, contains numerous LepRb neurons, suggesting a potential role for LepRb PMv neurons in transmitting both metabolic and odorant signals to the neuroendocrine reproductive system. Indeed, Fos-immunoreactivity (-IR) and electrophysiologic recordings revealed the direct activation of LepRb PMv neurons by leptin, and exposure to odors from mice of the opposite sex promoted Fos-IR in many LepRb PMv neurons. To determine the regions innervated by the LepRb PMv neurons, we utilized two novel cre-activated tract-tracing systems in Leprcre animals; data from these systems and from standard tracing techniques revealed that LepRb PMv neurons project to a subset of the regions, including the preoptic area (POA), that are innervated by the PMv as a whole. Furthermore, the retrograde accumulation in LepRb PMv neurons of a trans-synaptic tracer from GnRH neurons revealed the direct innervation of GnRH neurons by many LepRb PMv neurons. Thus, LepRb PMv neurons sense metabolic and sexual odorant cues and project to the rostral hypothalamus to directly innervate GnRH neurons. These results are consistent with a role for LepRb PMv neurons in regulating the reproductive axis in response to metabolic and odorant stimuli. PMID:19279251

  6. 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.

  7. 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. PMID:27256112

  8. Differential transport properties of D-leucine and L-leucine in the archaeon, Halobacterium salinarum.

    PubMed

    Tanaka, M; Mukohata, Y; Yuasa, S

    2000-04-01

    The transport of D-leucine was compared with that of L-leucine in Halobacterium salinarum. When a high-outside/low-inside Na+ gradient was imposed, D-leucine as well as L-leucine accumulated in envelope vesicles, supporting the hypothesis that D-leucine is transported via a symport system along with Na+. Kinetic analyses, including inhibition experiments, indicated that both enantiomers are transported via a common carrier. However, a Hill plot indicated a single binding site for Na+ during L-leucine transport, but dual binding sites for Na+ during D-leucine transport. Furthermore, D-leucine transport was dependent on electrical membrane potential, suggesting that a transporter bound with D-leucine is positively charged. L-leucine transport was slightly, if at all, dependent on membrane potential, suggesting that a transporter bound with L-leucine is electrically neutral. These results indicate that the leucine carrier in Halobacterium salinarum translocates two moles of Na+ per mole of D-leucine, and one mole of Na+ per mole of L-leucine. PMID:10779875

  9. Hypothalamic sidedness in mitochondrial metabolism: new perspectives.

    PubMed

    Toth, Istvan; Kiss, David Sandor; Goszleth, Greta; Bartha, Tibor; Frenyo, Laszlo V; Naftolin, Frederick; Horvath, Tamas L; Zsarnovszky, Attila

    2014-12-01

    Morphofunctional changes in hypothalamic neurons are highly energy dependent and rely on mitochondrial metabolism. Therefore, mitochondrial adenosine triphosphate production plays a permissive role in hypothalamic regulatory events. Here, we demonstrated that in the female rat hypothalamus, mitochondrial metabolism and tissue oxygenation show an asymmetric lateralization during the estrous cycle. This asymmetry was not detected in males. The observed sidedness suggests that estrous cycle-linked hypothalamic functions in females are based on hemispheric distinction. The novel concept of hypothalamic asymmetry necessitates the revision of hypothalamic neural circuits, synaptic reorganization, and the role of hypothalamic sides in the regulation of integrated homeostatic functions. PMID:24740989

  10. Regulation of Leucine Biosynthesis in Bacillus subtilis

    PubMed Central

    Ward, Jonathan B.; Zahler, Stanley A.

    1973-01-01

    The biosynthesis of α-isopropylmalate (αIPM) synthetase, IPM isomerase, and βIPM dehydrogenase in Bacillus subtilis can be derepressed in leucine auxotrophs by limiting them for leucine. The derepression of the three enzymes is apparently coordinate. A class of mutants resistant to 4-azaleucine excretes leucine and has derepressed levels of all three enzymes. The azaleucine-resistance mutations may lie in a gene (azlA) encoding a repressor. Efforts to find mutations characteristic of a constitutive operator have been unsuccessful. No polar mutations have been found among nine leucine auxotrophs that have characteristics of frameshift mutations. The enzyme catalyzing the first step in leucine biosynthesis, αIPM synthetase, is sensitive to feedback inhibition by leucine. We conclude that leucine biosynthesis is controlled by the inhibition of the activity of the first biosynthetic enzyme by leucine, and by the repression of the synthesis of the first three biosynthetic enzymes by leucine. The repression of the three enzymes may be under the control of a single repressor and a single operator, or of a single repressor and a separate operator for each structural gene. PMID:4200854

  11. 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.

  12. 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.

  13. 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

  14. Hypothalamic signaling mechanisms in hypertension.

    PubMed

    Carmichael, Casey Y; Wainford, Richard D

    2015-05-01

    The etiology of hypertension, a critical public health issue affecting one in three US adults, involves the integration of the actions of multiple organ systems, including the central nervous system. Increased activation of the central nervous system, driving enhanced sympathetic outflow and increased blood pressure, has emerged as a major contributor to the pathogenesis of hypertension. The hypothalamus is a key brain site acting to integrate central and peripheral inputs to ultimately impact blood pressure in multiple disease states that evoke hypertension. This review highlights recent advances that have identified novel signal transduction mechanisms within multiple hypothalamic nuclei (e.g., paraventricular nucleus, arcuate nucleus) acting to drive the pathophysiology of hypertension in neurogenic hypertension, angiotensin II hypertension, salt-sensitive hypertension, chronic intermittent hypoxia, and obesity-induced hypertension. Increased understanding of hypothalamic activity in hypertension has the potential to identify novel targets for future therapeutic interventions designed to treat hypertension. PMID:25860531

  15. Hypothalamic lipophagy and energetic balance.

    PubMed

    Singh, Rajat

    2011-10-01

    Autophagy is a conserved cellular turnover process that degrades unwanted cytoplasmic material within lysosomes. Through "in bulk" degradation of cytoplasmic proteins and organelles, including lipid droplets, autophagy helps provide an alternative fuel source, in particular, when nutrients are scarce. Recent work demonstrates a role for autophagy in hypothalamic agouti-related peptide (AgRP) neurons in regulation of food intake and energy balance. The induction of autophagy in hypothalamic neurons during starvation mobilizes neuronal neutral lipids to generate neuron-intrinsic free fatty acids that serve to upregulate fasting-induced AgRP levels. Blocking autophagy in AgRP neurons in mice reduces fasting-induced food intake, and increases constitutive levels of anorexigenic hypothalamic proopiomelanocortin and its cleavage product α-melanocyte stimulating hormone. The energetic consequences of these molecular events are decreased body weight and reduced adiposity. The present article discusses this recent finding, as well as considers possible future directions that may help better understand how neuronal autophagy, and its possible reduction during aging, may affect whole body energy balance. PMID:22024462

  16. Compartmental model of leucine kinetics in humans.

    PubMed

    Cobelli, C; Saccomani, M P; Tessari, P; Biolo, G; Luzi, L; Matthews, D E

    1991-10-01

    The complexity of amino acid and protein metabolism has limited the development of comprehensive, accurate whole body kinetic models. For leucine, simplified approaches are in use to measure in vivo leucine fluxes, but their domain of validity is uncertain. We propose here a comprehensive compartmental model of the kinetics of leucine and alpha-ketoisocaproate (KIC) in humans. Data from a multiple-tracer administration were generated with a two-stage (I and II) experiment. Six normal subjects were studied. In experiment I, labeled leucine and KIC were simultaneously injected into plasma. Four plasma leucine and KIC tracer concentration curves and label in the expired CO2 were measured. In experiment II, labeled bicarbonate was injected into plasma, and labeled CO2 in the expired air was measured. Radioactive (L-[1-14C]leucine, [4,5-3H]KIC, [14C]bicarbonate) and stable isotope (L-[1-13C]leucine, [5,5,5-2H3]KIC, [13C]bicarbonate) tracers were employed. The input format was a bolus (impulse) dose in the radioactive case and a constant infusion in the stable isotope case. A number of physiologically based, linear time-invariant compartmental models were proposed and tested against the data. The model finally chosen for leucine-KIC kinetics has 10 compartments: 4 for leucine, 3 for KIC, and 3 for bicarbonate. The model is a priori uniquely identifiable, and its parameters were estimated with precision from the five curves of experiment I. The separate assessment of bicarbonate kinetics (experiment II) was shown to be unnecessary. The model defines masses and fluxes of leucine in the organism, in particular its intracellular appearance from protein breakdown, its oxidation, and its incorporation into proteins. An important feature of the model is its ability to estimate leucine oxidation by resolving the bicarbonate model in each individual subject. Finally, the model allows the assessment of the domain of validity of the simpler commonly used models. PMID:1928344

  17. A genomic atlas of mouse hypothalamic development

    PubMed Central

    Shimogori, Tomomi; Lee, Daniel A; Miranda-Angulo, Ana; Yang, Yanqin; Wang, Hong; Jiang, Lizhi; Yoshida, Aya C; Kataoka, Ayane; Mashiko, Hiromi; Avetisyan, Marina; Qi, Lixin; Qian, Jiang; Blackshaw, Seth

    2014-01-01

    The hypothalamus is a central regulator of many behaviors that are essential for survival, such as temperature regulation, food intake and circadian rhythms. However, the molecular pathways that mediate hypothalamic development are largely unknown. To identify genes expressed in developing mouse hypothalamus, we performed microarray analysis at 12 different developmental time points. We then conducted developmental in situ hybridization for 1,045 genes that were dynamically expressed over the course of hypothalamic neurogenesis. We identified markers that stably labeled each major hypothalamic nucleus over the entire course of neurogenesis and constructed a detailed molecular atlas of the developing hypothalamus. As a proof of concept of the utility of these data, we used these markers to analyze the phenotype of mice in which Sonic Hedgehog (Shh) was selectively deleted from hypothalamic neuroepithelium and found that Shh is essential for anterior hypothalamic patterning. Our results serve as a resource for functional investigations of hypothalamic development, connectivity, physiology and dysfunction. PMID:20436479

  18. 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. PMID:26071958

  19. Hypothalamic miRNAs: emerging roles in energy balance control

    PubMed Central

    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. PMID:25729348

  20. Nonsocial functions of hypothalamic oxytocin.

    PubMed

    Yang, Hai-Peng; Wang, Liwei; Han, Liqun; Wang, Stephani C

    2013-01-01

    Oxytocin (OXT) is a hypothalamic neuropeptide composed of nine amino acids. The functions of OXT cover a variety of social and nonsocial activity/behaviors. Therapeutic effects of OXT on aberrant social behaviors are attracting more attention, such as social memory, attachment, sexual behavior, maternal behavior, aggression, pair bonding, and trust. The nonsocial behaviors/functions of brain OXT have also received renewed attention, which covers brain development, reproduction, sex, endocrine, immune regulation, learning and memory, pain perception, energy balance, and almost all the functions of peripheral organ systems. Coordinating with brain OXT, locally produced OXT also involves the central and peripheral actions of OXT. Disorders in OXT secretion and functions can cause a series of aberrant social behaviors, such as depression, autism, and schizophrenia as well as disturbance of nonsocial behaviors/functions, such as anorexia, obesity, lactation failure, osteoporosis, diabetes, and carcinogenesis. As more and more OXT functions are identified, it is essential to provide a general view of OXT functions in order to explore the therapeutic potentials of OXT. In this review, we will focus on roles of hypothalamic OXT on central and peripheral nonsocial functions. PMID:24967304

  1. 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. PMID:26898942

  2. 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...

  3. 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...

  4. Hypothalamic eIF2α signaling regulates food intake.

    PubMed

    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

    2014-02-13

    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

  5. 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

  6. 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

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

    PubMed

    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

  8. LEUCINE STIMULATION OF SKELETAL MUSCLE PROTEIN SYNTHESIS DURING PROLONGED LEUCINE INFUSION IS DEPENDENT ON AMINO ACID AVAILABILITY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leucine stimulates protein synthesis in cultured cells, mature rats and neonatal pigs. We have reported that leucine infusion increases protein synthesis in skeletal muscle of neonatal pigs during a 60-min infusion. When leucine infusion was prolonged for 120 min, however, protein synthesis was no...

  9. Systemic exchangeability of enteral leucine: relationship to plasma flux

    SciTech Connect

    Istfan, N.W.; Ling, P.R.; Bistrian, B.R.; Blackburn, G.L.

    1988-04-01

    The exchangeability of enterally infused leucine within the systemic compartment was estimated in fasted and fed rats using L-(1-/sup 14/C)leucine as a tracer. The experimental design consisted of enteral and parenteral feedings with intravenous or intragastric tracer infusions. During continuous intragastric feeding, only 73 +/- 6% (SE) of the intragastric leucine tracer infusion was accounted for in the systemic circulation. When comparing intravenous vs. intragastric tracer, the estimate of the contribution of protein breakdown to plasma leucine flux was 6 +/- 1 (SE) mumol.h-1.100 g-1 and 18 +/- 3 (SE) mumol.h-1.100 g-1 (P less than 0.01), respectively, for the two routes of administration. Correction of enteral input (either isotope or total leucine), by a factor of 27% for first-pass extraction, eliminated all significant differences in plasma leucine kinetics. Of the 27% of enterally infused tracer not appearing systemically, only 3% could be accounted for in newly synthesized protein in the liver. The remainder is hypothesized to represent first-pass utilization of leucine in intestinal protein synthesis and other metabolic pathways in the splanchnic bed. In contrast, systemic appearance of enteral leucine was essentially complete in the fasted rats, indicating less splanchnic metabolism of leucine in this state. These data indicate that significant error can result in estimating the contribution of endogenous protein breakdown to plasma leucine flux during feeding if the systemic exchangeability of dietary leucine is not considered.

  10. 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

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

    PubMed

    Wu, Xiaochun; Zhao, Lingling; 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

  12. Hypothalamic neuronal responses to cytokines.

    PubMed Central

    Shibata, M.

    1990-01-01

    Fever has been extensively studied in the past few decades. The hypothesis that hypothalamic thermosensitive neurons play a major role in both normal thermoregulation and in fever production and lysis has particularly helped to advance our understanding of the neuronal mechanisms underlying the response to pyrogens. Furthermore, new data in the study of host defense responses induced by pyrogenic cytokines such as interleukin 1, interferon alpha 2, tumor necrosis factor alpha, and interleukin 6 have demonstrated that those factors have multiple, yet coordinated, regulatory activities in the central nervous system, so that our understanding of the role of the brain in the activity of these agents requires a new perspective and dimension. Thus, recent evidence from our laboratory indicates that blood-borne cytokines may be detected in the organum vasculosum laminae terminalis and transduced there into neuronal signals. Such signals may then affect distinct, but partially overlapping, sets of neuronal systems in the preoptic area of the anterior hypothalamus, mediating directly and/or indirectly the array of various host defense responses characteristic of infection that are thought to be induced by blood-borne cytokines. PMID:2205055

  13. Kinetics of sequential metabolism from D-leucine to L-leucine via alpha-ketoisocaproic acid in rat.

    PubMed

    Hasegawa, Hiroshi; Matsukawa, Takehisa; Shinohara, Yoshihiko; Hashimoto, Takao

    2002-12-01

    D-Leucine is considered to be converted into the L-enantiomer by two steps: oxidative deamination to form alpha-ketoisocaproic acid (KIC) and subsequent stereospecific reamination of KIC. We investigated the pharmacokinetics of leucine enantiomers and KIC in rats to evaluate how deamination of D-leucine, reamination of KIC, and decarboxylation of KIC were affected to the overall extent that converted D-leucine into the L-enantiomer. After intravenous administrations of D-[(2)H(7)]leucine, L-[(2)H(7)]leucine, or [(2)H(7)]KIC, their plasma concentrations together with endogenous L-leucine and KIC were determined by gas chromatography-mass spectrometry. The rapid appearances of [(2)H(7)]KIC and L-[(2)H(7)]leucine were observed after administration of D-[(2)H(7)]leucine, whereas no detectable amount of D-[(2)H(7)]leucine was found after administrations of [(2)H(7)]KIC or L-[(2)H(7)]leucine. The fraction of conversion from D-[(2)H(7)]leucine into [(2)H(7)]KIC (F(D-->KIC)) was estimated by using the area under the curve (AUC) of [(2)H(7)]KIC on the D-[(2)H(7)]leucine administration [AUC(KIC(D))] and that of [(2)H(7)]KIC on the [(2)H(7)]KIC administration (AUC(KIC)) to yield 70.1%. The fraction of conversion from [(2)H(7)]KIC to L-[(2)H(7)]leucine (F(KIC-->L)) was 40.2%. The fraction of conversion from D-leucine to the L-enantiomer (F(D-->L)) was considered to be the product of F(D-->KIC) and F(KIC-->L), indicating that 28.2% of D-[(2)H(7)]leucine was metabolized to L-[(2)H(7)]leucine via [(2)H(7)]KIC. These results suggested that the relatively low conversion of D-leucine into the L-enantiomer might depend on irreversible decarboxylation of KIC. Regardless of [(2)H(7)]KIC, F(D-->L) was also calculated directly using AUC(L(D)) and AUC(L) to yield 27.5%. There were no differences between the two F(D-->L) values, suggesting that almost all of the formation of L-[(2)H(7)]leucine from D-[(2)H(7)]leucine occurred via [(2)H(7)]KIC as an intermediate. PMID:12433816

  14. 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

  15. 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.

  16. 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. PMID:27417254

  17. Pathway for isoleucine formation form pyruvate by leucine biosynthetic enzymes in leucine-accumulating isoleucine revertants of Serratia marcescens.

    PubMed

    Kisumi, M; Komatsubara, S; Chibata, I

    1977-07-01

    Leaky revertants isolated from isoleucine auxotrophs of Serratia marcescens mutant resistant to alpha-aminobutyric acid were previously reported to accumulate leucine in the medium, due to the absence of both feedback inhibition and repression of leucine biosynthesis. Growth of the revertant was accelerated by pyruvate, D(-)-citramalate, citraconate, and alpha-ketobutyrate, but not by threonine. Extracts of the revertant exhibited high activities of pyruvate-dependent coenzyme A liberation from acetyl-coenzyme A, hydration of citraconate, and conversion of citraconate to alpha-ketobutyrate, but showed no threonine-deaminating activity. In the leucine-accumulating revertants the above three activities were not affected by leucine, but in the wild strain and other revertants accumulating no leucine all or one of these activities was controlled by leucine. A leucine auxotroph isolated from the leucine-accumulating revertant showed isoleucine auxotrophy as well. From these data, it is concluded that, in leucine-accumulating revertants, of S. marcescent, isoleucine, is synthesized from alpha-ketobutyrate via citramalate formed from pyruvate annd acetyl-coenzyme A by leucine biosynthetic enzymes, as a result of desensitization of alpha-isopropylmalate synthetase to feedback inhibition. PMID:142769

  18. 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

  19. 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. PMID:26054437

  20. 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. PMID:26724922

  1. 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. PMID:25575457

  2. 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.

  3. 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

  4. Protein and leucine metabolism in maple syrup urine disease

    SciTech Connect

    Thompson, G.N.; Bresson, J.L.; Pacy, P.J.; Bonnefont, J.P.; Walter, J.H.; Leonard, J.V.; Saudubray, J.M.; Halliday, D. )

    1990-04-01

    Constant infusions of (13C)leucine and (2H5)phenylalanine were used to trace leucine and protein kinetics, respectively, in seven children with maple syrup urine disease (MSUD) and eleven controls matched for age and dietary protein intake. Despite significant elevations of plasma leucine (mean 351 mumol/l, range 224-477) in MSUD subjects, mean whole body protein synthesis (3.78 +/- 0.42 (SD) g.kg-1. 24 h-1) and catabolism (4.07 +/- 0.46) were similar to control values (3.69 +/- 0.50 and 4.09 +/- 0.50, respectively). The relationship between phenylalanine and leucine fluxes was also similar in MSUD subjects (mean phenylalanine-leucine flux ratio 0.35 +/- 0.07) and previously reported adult controls (0.33 +/- 0.02). Leucine oxidation was undetectable in four of the MSUD subjects and very low in the other three (less than 4 mumol.kg-1.h-1; controls 13-20). These results show that persistent elevation in leucine concentration has no effect on protein synthesis. The marked disturbance in leucine metabolism in MSUD did not alter the relationship between rates of catabolism of protein to phenylalanine and leucine, which provides further support for the validity of the use of a single amino acid to trace whole body protein metabolism. The minimal leucine oxidation in MSUD differs from findings in other inborn metabolic errors and indicates that in patients with classical MSUD there is no significant route of leucine disposal other than through protein synthesis.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  6. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 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 Systems § 862.1460 Leucine aminopeptidase...

  7. Leucine for retention of lean mass on a hypocaloric diet.

    PubMed

    Jitomir, Jean; Willoughby, Darryn S

    2008-12-01

    As obesity rates continue to climb, there is a pressing need for novel weight loss techniques. However, the energy-restricted diets recommended for weight loss typically result in significant amounts of lean tissue loss, in addition to the desired body fat loss. Leucine, a supported anticatabolic agent, has shown promise in research at many levels. First, leucine is known to stimulate the mammalian target of rapamycin pathway, which initiates translation and protein synthesis in muscle cells. Furthermore, leucine may help to regulate blood glucose levels by promoting gluconeogenesis. Finally, several recent studies provide evidence that leucine aids in the retention of lean mass in a hypocaloric state. The aim of this paper is to review relevant leucine research in the three areas described and assess its potential as supplement for obese individuals. PMID:19053849

  8. 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

  9. MECHANISMS IN ENDOCRINOLOGY: Hypothalamic inflammation and nutrition.

    PubMed

    Araujo, Eliana P; Moraes, Juliana C; Cintra, Dennys E; Velloso, Licio A

    2016-09-01

    Selected subpopulations of hypothalamic neurons play important roles in the regulation of whole body energy homeostasis. Studies have shown that the saturated fats present in large amounts in western diets can activate an inflammatory response in the hypothalamus, affecting the capacity of such neurons to respond appropriately to satiety and adipostatic signals. In the first part of this review, we will explore the mechanisms behind saturated fatty acid-induced hypothalamic dysfunction. Next, we will present and discuss recent studies that have identified the mechanisms that mediate some of the anti-inflammatory actions of unsaturated fatty acids in the hypothalamus and the potential for exploring these mechanisms to prevent or treat obesity. PMID:27006108

  10. 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

  11. Hypothalamic survival circuits: blueprints for purposive behaviors.

    PubMed

    Sternson, Scott M

    2013-03-01

    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

  12. Hypothalamic and pancreatic lesions with diabetes mellitus.

    PubMed Central

    Shuangshoti, S; Samranvej, P

    1975-01-01

    A case is reported of a neoplasm of mixed mesenchymal and neuroepithelial origin consisting of plasmacytoma, lymphoma, ganglioneuroma, and astrocytoma in the same mass. The tumour arose in the hypothalamus of a 43 year old diabetic woman who also had alpha cell hyperplasia and beta cell hypoplasia of the islets of Langerhans. It is suggested that both hypothalamic and pancreatic lesions produced diabetes mellitus in this patient. Images PMID:1104774

  13. Effects of Hypothalamic Neurodegeneration on Energy Balance

    PubMed Central

    2005-01-01

    Normal aging in humans and rodents is accompanied by a progressive increase in adiposity. To investigate the role of hypothalamic neuronal circuits in this process, we used a Cre-lox strategy to create mice with specific and progressive degeneration of hypothalamic neurons that express agouti-related protein (Agrp) or proopiomelanocortin (Pomc), neuropeptides that promote positive or negative energy balance, respectively, through their opposing effects on melanocortin receptor signaling. In previous studies, Pomc mutant mice became obese, but Agrp mutant mice were surprisingly normal, suggesting potential compensation by neuronal circuits or genetic redundancy. Here we find that Pomc-ablation mice develop obesity similar to that described for Pomc knockout mice, but also exhibit defects in compensatory hyperphagia similar to what occurs during normal aging. Agrp-ablation female mice exhibit reduced adiposity with normal compensatory hyperphagia, while animals ablated for both Pomc and Agrp neurons exhibit an additive interaction phenotype. These findings provide new insight into the roles of hypothalamic neurons in energy balance regulation, and provide a model for understanding defects in human energy balance associated with neurodegeneration and aging. PMID:16296893

  14. 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. PMID:26786898

  15. Hypothalamic CRF immunoreactivity in genetically hypothyroid (hyt/hyt) mice.

    PubMed

    Meserve, L A

    1987-07-01

    The induction of hypothyroidism in young rats by feeding thiouracil to their mothers during pregnancy has been shown to depress hypothalamic content of bioactive and immunoactive corticotropin-releasing factor (CRF). The present study was done to determine whether genetically hypothyroid young mice (hyt/hyt) born to euthyroid mothers (+/hyt) exhibited a similar depression in hypothalamic CRF immunoreactivity. Young euthyroid and hypothyroid littermate mice were examined by radioimmunoassay for hypothalamic CRF content at 15, 20, 25, or 30 days of age. Mean CRF content was depressed insignificantly (to about 80% of normal) by hypothyroidism, at 15-25 days of age. However, after weaning by the mother, 30-day-old hypothyroid pups demonstrated significantly depressed hypothalamic CRF levels (71%). It is suggested that maternal factors may be assisting in the maintenance of hypothalamic CRF until after weaning. Furthermore, genetic hypothyroidism does not appear to have nearly as marked an influence as thiouracil feeding on hypothalamic CRF levels. PMID:3496606

  16. Activation of nuclear factor kappa B pathway and reduction of hypothalamic oxytocin following hypothalamic lesions

    PubMed Central

    Roth, Christian L.; D’Ambrosio, Gabrielle; Elfers, Clinton

    2016-01-01

    Background Hypothalamic obesity (HO) occurs in patients with tumors and lesions in the medial hypothalamic region. In this study, a hyperphagic rat model of combined medial hypothalamic lesions (CMHL) was used to test which specific inflammatory molecules are involved. Methods In order to target specific homeostatic medial hypothalamic nuclei (arcuate, ventromedial, and dorsomedial nuclei), male Sprague-Dawley rats (age of 8 weeks, ~250 g body weight) received four electrolytic lesions or sham surgery. Post-surgery food intake and weight changes were tracked and hypothalamic gene expression for inflammatory molecules as well as anorexigenic peptide oxytocin 7 days and 7 months post-surgery were tested. Results Seven days post-surgery, average food intake increased by 23%, and body weight gain had increased by 68%. Toll-like 4 receptor/nuclear factor–κB (TLR4/NF–κB)—pathway was specifically activated in the mediobasal hypothalamus (MBH), resulting in 3-fold higher tumor necrosis factor (TNF)-α, 10-fold higher interleukin (IL) 1-β mRNA levels, and higher expression of suppression of cytokine signaling (SOCS) 3, while oxytocin mRNA levels were significantly reduced in CMHL rats versus sham surgery rats 7 days post-surgery. At 7 months, inflammation was less stimulated in MBH of CMHL rats compared to 7 days post-surgery and SOCS 3 as well as oxytocin mRNA levels were comparable between the two groups. Conclusion Medial hypothalamic lesions are associated with strong post-surgery hyperphagia and activation of TLR4/NF–κB—pathway as well as reduced expression of oxytocin in the hypothalamus.

  17. 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. PMID:24880214

  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. PMID:26481769

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

    PubMed

    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

  1. 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

  2. Molecular regulation of hypothalamic development and physiological functions.

    PubMed

    Gao, Yanxia; Sun, Tao

    2016-09-01

    The hypothalamus is composed of many heterogeneous nuclei that control distinct physiological functions. Investigating molecular mechanisms that regulate the specification of these nuclei and specific neuronal subtypes, and their contribution to diverse hypothalamic functions, is an exciting research focus. Here, we begin by summarizing the hypothalamic functions of feeding regulation, sleep-wake cycles, stress responses, and circadian rhythm, and describing their anatomical bases. Next, we review the molecular regulation of formation of hypothalamic territories, specification of nuclei and subnuclei, and generation of specific neurons. Finally, we highlight physiological and behavioral consequences of altered hypothalamic development. Identifying molecules that regulate hypothalamic development and function will increase our understanding of hypothalamus-related disorders, such as obesity and diabetes, and aid in the development of therapies aimed specifically at their etiologies. PMID:26223804

  3. MicroRNA-27a is induced by leucine and contributes to leucine-induced proliferation promotion in C2C12 cells.

    PubMed

    Chen, Xiaoling; Huang, Zhiqing; Chen, Daiwen; Yang, Ting; Liu, Guangmang

    2013-01-01

    Leucine, a branched chain amino acid, is well known to stimulate protein synthesis in skeletal muscle. However, the role of leucine in myoblast proliferation remains unclear. In this study, we found that leucine could promote proliferation of C2C12 cells. Moreover, expressions of miR-27a and myostatin (a bona fide target of miR-27a) were upregulated and downregulated, respectively, following leucine treatment. We also found that miR-27a loss-of-function by transfection of a miR-27a inhibitor suppressed the promotion of myoblast proliferation caused by leucine. Our results suggest that miR-27a is induced by leucine and contributes to leucine-induced proliferation promotion of myoblast. PMID:23880856

  4. 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.

  5. 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.

  6. Phosphate depletion impairs leucine-induced insulin secretion.

    PubMed

    Oh, H Y; Fadda, G Z; Smogorzewski, M; Liou, H H; Massry, S G

    1994-11-01

    Phosphate depletion (PD) in vivo causes a sundry of abnormalities in pancreatic islets including a rise in cytosolic calcium, low ATP content, reduced Ca2+ ATPase and Na(+)-K+ ATPase activity, and impaired insulin secretion in response to glucose or potassium. L-Leucine is a strong secretagogue that triggers insulin secretion by deamination to alpha-ketoisocaproic acid (KIC) and the subsequent metabolism of the latter to ATP and by the activation of glutamate dehydrogenase (GLDH), which acts on glutamate to generate alpha-ketoglutarate, the metabolism of which results in ATP production. The generation of ATP triggers events that lead to insulin secretion. It is not known whether PD impairs leucine-induced insulin secretion, and the cellular derangements that are involved in such an abnormality are not defined. These issues were studied in PD rats and in pair-weighed normal animals as controls. D-Leucine uptake by islets from PD rats is normal, but both leucine- and KIC-induced insulin secretions are impaired and the activity of branched-chain keto acid dehydrogenase, which facilitates the metabolism of KIC, is reduced. Both leucine and 2-aminobicyclo (2-2-1) haptene failed to stimulate GLDH and to augment the generation of alpha-ketoglutarate in the islets of PD rats. Also, the concentration of basal alpha-ketoglutarate was significantly higher in the islets of PD rats, suggesting that its metabolism is impaired. In addition, the activity of glutaminase is significantly reduced, an abnormality that would result in decreased production of glutamate, the substrate for GLDH. The data show that PD impairs leucine-induced insulin secretion.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7873737

  7. Hypothalamic Nesfatin-1 Stimulates Sympathetic Nerve Activity via Hypothalamic ERK Signaling.

    PubMed

    Tanida, Mamoru; Gotoh, Hitoshi; Yamamoto, Naoki; Wang, Mofei; Kuda, Yuhichi; Kurata, Yasutaka; Mori, Masatomo; Shibamoto, Toshishige

    2015-11-01

    Nesfatin-1 acts on the hypothalamus and regulates the autonomic nervous system. However, the hypothalamic mechanisms of nesfatin-1 on the autonomic nervous system are not well understood. In this study, we found that intracerebroventricular (ICV) administration of nesfatin-1 increased the extracellular signal-regulated kinase (ERK) activity in rats. Furthermore, the activity of sympathetic nerves, in the kidneys, liver, and white adipose tissue (WAT), and blood pressure was stimulated by the ICV injection of nesfatin-1, and these effects were abolished owing to pharmacological inhibition of ERK. Renal sympathoexcitatory and hypertensive effects were also observed with nesfatin-1 microinjection into the paraventricular hypothalamic nucleus (PVN). Moreover, nesfatin-1 increased the number of phospho (p)-ERK1/2-positive neurons in the PVN and coexpression of the protein in neurons expressing corticotropin-releasing hormone (CRH). Pharmacological blockade of CRH signaling inhibited renal sympathetic and hypertensive responses to nesfatin-1. Finally, sympathetic stimulation of WAT and increased p-ERK1/2 levels in response to nesfatin-1 were preserved in obese animals such as rats that were fed a high-fat diet and leptin receptor-deficient Zucker fatty rats. These findings indicate that nesfatin-1 regulates the autonomic nervous system through ERK signaling in PVN-CRH neurons to maintain cardiovascular function and that the antiobesity effect of nesfatin-1 is mediated by hypothalamic ERK-dependent sympathoexcitation in obese animals. PMID:26310564

  8. 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. PMID:26814589

  9. 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

  10. 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

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

    PubMed

    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

  12. Memory enhancement induced by hypothalamic/fornix deep brain stimulation.

    PubMed

    Hamani, Clement; McAndrews, Mary Pat; Cohn, Melanie; Oh, Michael; Zumsteg, Dominik; Shapiro, Colin M; Wennberg, Richard A; Lozano, Andres M

    2008-01-01

    Bilateral hypothalamic deep brain stimulation was performed to treat a patient with morbid obesity. We observed, quite unexpectedly, that stimulation evoked detailed autobiographical memories. Associative memory tasks conducted in a double-blinded "on" versus "off" manner demonstrated that stimulation increased recollection but not familiarity-based recognition, indicating a functional engagement of the hippocampus. Electroencephalographic source localization showed that hypothalamic deep brain stimulation drove activity in mesial temporal lobe structures. This shows that hypothalamic stimulation in this patient modulates limbic activity and improves certain memory functions. PMID:18232017

  13. The Brain-to-Pancreatic Islet Neuronal Map Reveals Differential Glucose Regulation From Distinct Hypothalamic Regions.

    PubMed

    Rosario, Wilfredo; Singh, Inderroop; Wautlet, Arnaud; Patterson, Christa; Flak, Jonathan; Becker, Thomas C; Ali, Almas; Tamarina, Natalia; Philipson, Louis H; Enquist, Lynn W; Myers, Martin G; Rhodes, Christopher J

    2016-09-01

    The brain influences glucose homeostasis, partly by supplemental control over insulin and glucagon secretion. Without this central regulation, diabetes and its complications can ensue. Yet, the neuronal network linking to pancreatic islets has never been fully mapped. Here, we refine this map using pseudorabies virus (PRV) retrograde tracing, indicating that the pancreatic islets are innervated by efferent circuits that emanate from the hypothalamus. We found that the hypothalamic arcuate nucleus (ARC), ventromedial nucleus (VMN), and lateral hypothalamic area (LHA) significantly overlap PRV and the physiological glucose-sensing enzyme glucokinase. Then, experimentally lowering glucose sensing, specifically in the ARC, resulted in glucose intolerance due to deficient insulin secretion and no significant effect in the VMN, but in the LHA it resulted in a lowering of the glucose threshold that improved glucose tolerance and/or improved insulin sensitivity, with an exaggerated counter-regulatory response for glucagon secretion. No significant effect on insulin sensitivity or metabolic homeostasis was noted. Thus, these data reveal novel direct neuronal effects on pancreatic islets and also render a functional validation of the brain-to-islet neuronal map. They also demonstrate that distinct regions of the hypothalamus differentially control insulin and glucagon secretion, potentially in partnership to help maintain glucose homeostasis and guard against hypoglycemia. PMID:27207534

  14. Leucine regulation of the ilvGEDA operon of Serratia marcescens by attenuation is modulated by a single leucine codon.

    PubMed Central

    Hsu, J H; Harms, E; Umbarger, H E

    1985-01-01

    The effect of leucine limitation and of restricted leucine tRNA charging on the expression of the ilvGEDA operon of Serratia marcescens was examined. In this organism, the ilv leader region specifies a putative peptide containing only a single leucine codon that could be involved in leucine-mediated control by attenuation (E. Harms, J.-H. Hsu, C. S. Subrahmanyam, and H. E. Umbarger, J. Bacteriol. 164:207-216, 1985). A plasmid (pPU134) containing the DNA of the S. marcescens ilv control region and three of the associated structural genes was studied as a single chromosomal copy in an Escherichia coli strain auxotrophic for all three branched-chain amino acids. The S. marcescens ilv genes responded to a multivalent control similar to that found in other enteric organisms. Furthermore, the S. marcescens ilv genes were derepressed when the charging of leucine tRNA was restricted in a leuS derivative of E. coli that had been transformed with pPU134. It was concluded that ribosome stalling leading to deattenuation is not dependent on either tandem or a consecutive series of codons for the regulatory amino acid. However, the fact that the single leucine codon is a less frequently used codon (CUA) may be important. The procedure for obtaining the cloned ilv genes in single chromosomal copy exploited the dependence of ColE1 replicons on the polA gene. The cloning experiments also revealed a branched-chain amino acid-glutamate transaminase in S. marcescens that is different from transaminase B. PMID:3900038

  15. Role of hypothalamic adenosine 5'-monophosphate-activated protein kinase in the impaired counterregulatory response induced by repetitive neuroglucopenia.

    PubMed

    Alquier, Thierry; Kawashima, Junji; Tsuji, Youki; Kahn, Barbara B

    2007-03-01

    Antecedent hypoglycemia blunts counterregulatory responses that normally restore glycemia, a phenomenon known as hypoglycemia-associated autonomic failure (HAAF). The mechanisms leading to impaired counterregulatory responses are largely unknown. Hypothalamic AMP-activated protein kinase (AMPK) acts as a glucose sensor. To determine whether failure to activate AMPK could be involved in the etiology of HAAF, we developed a model of HAAF using repetitive intracerebroventricular (icv) injection of 2-deoxy-D-glucose (2DG) resulting in transient neuroglucopenia in normal rats. Ten minutes after a single icv injection of 2DG, both alpha1- and alpha2-AMPK activities were increased 30-50% in arcuate and ventromedial/dorsomedial hypothalamus but not in other hypothalamic regions, hindbrain, or cortex. Increased AMPK activity persisted in arcuate hypothalamus at 60 min after 2DG injection when serum glucagon and corticosterone levels were increased 2.5- to 3.4-fold. When 2DG was injected icv daily for 4 d, hypothalamic alpha1- and alpha2-AMPK responses were markedly blunted in arcuate hypothalamus, and alpha1-AMPK was also blunted in mediobasal hypothalamus 10 min after 2DG on d 4. Both AMPK isoforms were activated normally in arcuate hypothalamus at 60 min. Counterregulatory hormone responses were impaired by recurrent neuroglucopenia and were partially restored by icv injection of 5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside, an AMPK activator, before 2DG. Glycogen content increased 2-fold in hypothalamus after recurrent neuroglucopenia, suggesting that glycogen supercompensation could be involved in down-regulating the AMPK glucose-sensing pathway in HAAF. Thus, activation of hypothalamic AMPK may be important for the full counterregulatory hormone response to neuroglucopenia. Furthermore, impaired or delayed AMPK activation in specific hypothalamic regions may play a critical role in the etiology of HAAF. PMID:17185376

  16. Generation of neuropeptidergic hypothalamic neurons from human pluripotent stem cells

    PubMed Central

    Merkle, Florian T.; Maroof, Asif; Wataya, Takafumi; Sasai, Yoshiki; Studer, Lorenz; Eggan, Kevin; Schier, Alexander F.

    2015-01-01

    Hypothalamic neurons orchestrate many essential physiological and behavioral processes via secreted neuropeptides, and are relevant to human diseases such as obesity, narcolepsy and infertility. We report the differentiation of human pluripotent stem cells into many of the major types of neuropeptidergic hypothalamic neurons, including those producing pro-opiolemelanocortin, agouti-related peptide, hypocretin/orexin, melanin-concentrating hormone, oxytocin, arginine vasopressin, corticotropin-releasing hormone (CRH) or thyrotropin-releasing hormone. Hypothalamic neurons can be generated using a ‘self-patterning’ strategy that yields a broad array of cell types, or via a more reproducible directed differentiation approach. Stem cell-derived human hypothalamic neurons share characteristic morphological properties and gene expression patterns with their counterparts in vivo, and are able to integrate into the mouse brain. These neurons could form the basis of cellular models, chemical screens or cellular therapies to study and treat common human diseases. PMID:25670790

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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–...

  18. 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...

  19. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 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...

  20. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 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...

  1. 21 CFR 862.1460 - Leucine aminopeptidase test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 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...

  2. Plasma reciprocal pool specific activity predicts that of intracellular free leucine for protein synthesis

    SciTech Connect

    Horber, F.F.; Horber-Feyder, C.M.; Krayer, S.; Schwenk, W.F.; Haymond, M.W. )

    1989-09-01

    We previously proposed that, during the infusion of either labeled leucine or its alpha-ketoacid, alpha-ketoisocaproate (KIC), the plasma specific activity (SA) of the transaminated product of the infused tracer (reciprocal pool SA) may better reflect the intracellular leucine SA than the plasma SA of either infused tracer (primary pool SA). To test this hypothesis, 14 dogs were simultaneously infused intravenously with (3H)leucine and (14C)KIC, and blood and tissue compartments were sampled. The ratios of (3H)-leucine to (14C)leucine (3H)/(14C)leucine in mixed tissue proteins and in the intracellular space of striated muscle were the same as the ratio of the isotope infusion rates and similar, although slightly lower (P less than 0.01), than (3H)KIC/(14C)leucine SA (ratio of reciprocal pool SA) in plasma. Plasma (3H)KIC/(14C)leucine SA were essentially identical to the (3H)/(14C) of leucine in (1) mixed liver proteins, (2) intrahepatic free leucine, and (3) fibrin. The (3H)/(14C)leucine in mixed renal proteins and in the intracellular space of kidney and erythrocytes were similar to those of the venous plasma (3H)/(14C)leucine SA. The plasma (3H)KIC and (14C)leucine SA (the reciprocal pool SA) were similar to the SA of (3H)- and (14C)leucine in the intracellular space of all organs investigated with the exception of kidney. Therefore, in postabsorptive dogs, the plasma SA of the transaminated product of the infused labeled KIC or leucine is an excellent predictor of the intracellular leucine SA in all tissues investigated with the exception of kidney.

  3. Rax regulates hypothalamic tanycyte differentiation and barrier function in mice

    PubMed Central

    Miranda-Angulo, Ana L.; Byerly, Mardi S.; Mesa, Janny; Wang, Hong; Blackshaw, Seth

    2013-01-01

    The wall of the ventral third ventricle is composed of two distinct cell populations: tanycytes and ependymal cells. Tanycytes regulate many aspects of hypothalamic physiology, but little is known about the transcriptional network that regulates their development and function. We observed that the retina and anterior neural fold homeobox transcription factor (Rax) is selectively expressed in hypothalamic tanycytes, and showed a complementary pattern of expression to markers of hypothalamic ependymal cells, such as Rarres2 (retinoic acid receptor responder). To determine whether Rax controls tanycyte differentiation and function, we generated Rax haploinsufficient mice and examined their cellular and molecular phenotype in adulthood. These mice appeared grossly normal, but careful examination revealed a thinning of the third ventricular wall and reduction of both tanycyte and ependymal markers. These experiments show that Rax is required for hypothalamic tanycyte and ependymal cell differentiation. Rax haploinsufficiency also resulted in the ectopic presence of ependymal cells in the α2 tanycytic zone, where few ependymal cells are normally found, suggesting that Rax is selectively required for α2 tanycyte differentiation. These changes in the ventricular wall were associated with reduced diffusion of Evans Blue tracer from the ventricle to the hypothalamic parenchyma, with no apparent repercussion on the gross anatomical or behavioral phenotype of these mice. In conclusion, we have provided evidence that Rax is required for the normal differentiation and patterning of hypothalamic tanycytes and ependymal cells, as well as for maintenance of the cerebrospinal fluid-hypothalamus barrier. PMID:23939786

  4. 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. PMID:24985571

  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. Hypothalamic proline rich polypeptide regulates hematopoiesis.

    PubMed

    Bezirganyan, Kristina B; Davtyan, Tigran K; Galoyan, Armen A

    2010-06-01

    The AGAPEPAEPAQPGVY proline-rich polypeptide (PRP-1) was isolated from neurosecretory granules of the bovine neurohypophysis; it is produced by N. supraopticus and N. paraventricularis. It has been shown that PRP-1 has many potentially beneficial biological effects including immunoregulatory, hematopoietic, antimicrobial and anti-neurodegenerative properties. Here we demonstrated that PRP-1 administration influence on redistribution of monocytes, granulocytes and lymphocytes between bone marrow (BM) and peripheral blood and promotes the influx of granulocytes and monocytes/macrophages from BM into peripheral blood and accumulation of immature granulocyte and monocyte in BM and delayed the maturation of T cells in BM. PRP-1 increased colony-forming cell proliferation in rat cells in vivo. In PRP-treated rat BM, the CFU number at day 4, 7 and 14 was considerably increased in comparison with untreated rats BM and no difference was found at day 21 and day 28. We found that PRP-1 enhances erythroid and myeloid colonies formation in human CD34(+) progenitor cell culture in the presence of different growth factors and down-regulates T cells colony formation and specific surface markers expression during induction of human CD34(+) progenitor cells differentiation into T lymphocytes lineage. We suggested that the hypothalamic PRP-1 possibly represents an endogenous peptide whose primary functions are to regulate neuronal survival and differentiation and hematopoiesis within neurosecretory hypothalamus-bone marrow humoral axis. PMID:20020325

  7. Hypothalamic neuropeptide signaling in alcohol addiction.

    PubMed

    Barson, Jessica R; Leibowitz, Sarah F

    2016-02-01

    The hypothalamus is now known to regulate alcohol intake in addition to its established role in food intake, in part through neuromodulatory neurochemicals termed neuropeptides. Certain orexigenic neuropeptides act in the hypothalamus to promote alcohol drinking, although they affect different aspects of the drinking response. These neuropeptides, which include galanin, the endogenous opioid enkephalin, and orexin/hypocretin, appear to stimulate alcohol intake not only through mechanisms that promote food intake but also by enhancing reward and reinforcement from alcohol. Moreover, these neuropeptides participate in a positive feedback relationship with alcohol, whereby they are upregulated by alcohol intake to promote even further consumption. They contrast with other orexigenic neuropeptides, such as melanin-concentrating hormone and neuropeptide Y, which promote alcohol intake under limited circumstances, are not consistently stimulated by alcohol, and do not enhance reward. They also contrast with neuropeptides that can be anorexigenic, including the endogenous opioid dynorphin, corticotropin-releasing factor, and melanocortins, which act in the hypothalamus to inhibit alcohol drinking as well as reward and therefore counter the ingestive drive promoted by orexigenic neuropeptides. Thus, while multiple hypothalamic neuropeptides may work together to regulate different aspects of the alcohol drinking response, excessive signaling from orexigenic neuropeptides or inadequate signaling from anorexigenic neuropeptides can therefore allow alcohol drinking to become dysregulated. PMID:25689818

  8. 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

  9. 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

  10. 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. PMID:26007290

  11. Paramagnetic molecular centers in the gamma-irradiated novel compound of aluminum and leucine, Al 6O 4(OH) 10(leucine) 2·5H 2O

    NASA Astrophysics Data System (ADS)

    Nothig-Laslo, Vesna; Himdan, Takialdin A.; Bilinski, Halka

    A new microcrystalline compound Al 6O 4(OH) 10(leucine) 2·5H 2O of possible biological and biochemical interest has been prepared and characterized by chemical analysis, i.r. spectrum, X-ray diffraction and thermogravimetric analysis. It was exposed to γ-irradiation at 77 K and at room temperature. Paramagnetic species formed were studied by ESR spectroscopy. The leucine radical ? has been identified which seems to be stabilized in the aluminium leucine compound by crystalline water. Coordinated leucine molecule in aluminium hydroxide acts as a trap for γ-irradiation energy.

  12. Leucine Metabolism in T Cell Activation: mTOR Signaling and Beyond.

    PubMed

    Ananieva, Elitsa A; Powell, Jonathan D; Hutson, Susan M

    2016-07-01

    In connection with the increasing interest in metabolic regulation of the immune response, this review discusses current advances in understanding the role of leucine and leucine metabolism in T lymphocyte (T cell) activation. T cell activation during the development of an immune response depends on metabolic reprogramming to ensure that sufficient nutrients and energy are taken up by the highly proliferating T cells. Leucine has been described as an important essential amino acid and a nutrient signal that activates complex 1 of the mammalian target of rapamycin (mTORC1), which is a critical regulator of T cell proliferation, differentiation, and function. The role of leucine in these processes is further discussed in relation to amino acid transporters, leucine-degrading enzymes, and other metabolites of leucine metabolism. A new model of T cell regulation by leucine is proposed and outlines a chain of events that leads to the activation of mTORC1 in T cells. PMID:27422517

  13. Characterization of Leucine Auxotrophs of the White Rot Basidiomycete Phanerochaete chrysosporium

    PubMed Central

    Molskness, Theodore A.; Alic, Margaret; Gold, Michael H.

    1986-01-01

    Six leucine auxotrophic strains of the white rot basidiomycete Phanerochaete chrysosporium were characterized genetically and biochemically. Complementation studies involving the use of heterokaryons identified three leucine complementation groups. Since all of the leucine auxotrophs grew on minimal medium supplemented with α-ketoisocaproate as well as with leucine, the transaminase catalyzing the last step in the leucine pathway was apparently normal in all strains. Therefore, the wild-type, auxotrophic, and several heterokaryotic strains were assayed for the activities of the other enzymes specific to leucine biosynthesis. Leu2 and Leu4 strains (complementation group I) lacked only α-isopropylmalate synthase activity; Leu3 and Leu6 strains (group III) lacked isopropylmalate isomerase activity; and Leu1 and Leu5 strains (group II) lacked β-isopropylmalate dehydrogenase. Heterokaryons formed from leucine auxotrophs of different complementation groups had levels of activity for all three enzymes similar to those found in the wild-type strain. PMID:16347073

  14. 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

  15. 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

  16. 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

  17. Studies of different female rat models of hypothalamic obesity.

    PubMed

    Elfers, Clinton; Ralston, Melissa; Roth, Christian L

    2011-01-01

    Hypothalamic obesity (HO) is a major and unsolved problem in patients with medial hypothalamic lesions and is associated with hyperinsulinemia and hyperleptinemia. The purpose of this study was to create a rodent model that mimics metabolic changes in HO for use in therapeutic testing. Female Sprague-Dawley rats were used to test the individual and combined effects of two types of medial hypothalamic lesions: arcuate nucleus (ARC) lesions by injection of monosodium glutamate at neonatal age, and ventromedial nucleus (VMN) lesions by passing an anodal current through an electrode placed in the VMN at age 80 days. Adiposity in ARC-lesioned animals was associated with decreased food intake and stunted growth, while VMN lesions were associated with hyperphagia but not reduced growth. The greatest weight gain (weight at age 200 days 712 +/- 65 vs. 451 +/- 19 g in controls), hyperphagia (food intake 10 days following surgery 33 +/- 0.8 vs. 18.5 +/- 0.7 g/day in sham-treated rats), hyperinsulinemia and hyperleptinemia occurred in rats that received both ARC and VMN lesions. Thus, the combined medial hypothalamic lesions result in an obesity phenotype similar to that of patients that suffer from HO and are consequently more suitable for testing potential therapeutics for this disorder than lesions of single hypothalamic nuclei. PMID:21648279

  18. Hypothalamic thermal stimulation modulates vasopressin release in hyperosmotically stimulated rabbits.

    PubMed

    Keil, R; Gerstberger, R; Simon, E

    1994-10-01

    Under thermoneutral conditions conscious rabbits received systemic infusions of NaCl as hypertonic solution (90 mueq.min-1.kg body wt-1), which raised their plasma osmolality from 283 to 312 mosmol/kgH2O. Rabbits receiving isotonic saline served as controls. Hypertonic stimulation induced a 60% reduction of both respiratory frequency and evaporative water loss. Rectal temperature rose by 0.4 degrees C despite enhanced peripheral vasodilation as indicated by increased ear skin temperature. Plasma vasopressin (AVP), aldosterone (ALDO), and corticosterone (COR) were significantly elevated from 6 to 16 pg/ml, 90 to 180 pg/ml, and 17 to 40 ng/ml, respectively. To elucidate the importance of central temperature for AVP and adrenal corticosteroid release, hypothalamic thermal stimulations (20 min) were superimposed during established iso- and hyperosmotic steady-state conditions. Different from isosmotic controls, hyperosmotic animals responded to hypothalamic cooling (37 degrees C) with a significant decrease in plasma AVP from 16 to 13 pg/ml and to hypothalamic warming (41 degrees C) with a significant rise from 16 to 19 pg/ml. A weak temperature effect on COR release was also disclosed, especially of hypothalamic cooling, which significantly lowered plasma COR from 42 to 34 ng/ml. These results provide evidence for positive local temperature coefficients of hypothalamic control of AVP release and suggest a similar property also for the control of COR release by the hypothalamo-adenohypophysial axis. PMID:7943420

  19. 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.

  20. 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

  1. 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

  2. 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

  3. Efficient Generation of Hypothalamic Neurons from Human Pluripotent Stem Cells.

    PubMed

    Wang, Liheng; Egli, Dieter; Leibel, Rudolph L

    2016-01-01

    The hypothalamus comprises neuronal clusters that are essential for body weight regulation and other physiological functions. Insights into the complex cellular physiology of this region of the brain are critical to understanding the pathogenesis of obesity, but human hypothalamic cells are largely inaccessible for direct study. Here we describe a technique for generation of arcuate-like hypothalamic neurons from human pluripotent stem (hPS) cells. Early activation of SHH signaling and inhibition of BMP and TGFβ signaling, followed by timed inhibition of NOTCH, can efficiently differentiate hPS cells into NKX2.1+ hypothalamic progenitors. Subsequent incubation with BDNF induces the differentiation and maturation of pro-opiomelanocortin and neuropeptide Y neurons, which are major cell types in the arcuate hypothalamus. These neurons have molecular and cellular characteristics consistent with arcuate neurons. © 2016 by John Wiley & Sons, Inc. PMID:27367166

  4. Hypothalamic AMPK as a Regulator of Energy Homeostasis.

    PubMed

    Huynh, My Khanh Q; Kinyua, Ann W; Yang, Dong Joo; Kim, Ki Woo

    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

  5. 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

  6. Cybernetic principles in the systematic concept of hypothalamic feeding control.

    PubMed

    Fricke, Oliver; Lehmkuhl, Gerd; Pfaff, Donald W

    2006-02-01

    Research on biological mechanisms of eating behavior and related disorders, such as obesity and anorexia nervosa, has become a large field of research in the last 15 years. With the discovery of peptides related to hypothalamic control of food intake (e.g. leptin and ghrelin) the search for the biological 'master key' of feeding control was renewed. As a result, mid-20th century biological concepts based on systematic and cybernetic thoughts fell into oblivion. This review highlights discoveries of hypothalamic-controlled feeding and eating behavior with a cybernetic and systematic perspective. Interestingly, older ideas of hypothalamic function offer possibilities for the incorporation of new molecular discoveries into systematic concepts of feeding behavior. PMID:16452529

  7. Transcription attenuation in Salmonella typhimurium: the significance of rare leucine codons in the leu leader.

    PubMed Central

    Carter, P W; Bartkus, J M; Calvo, J M

    1986-01-01

    The leucine operon of Salmonella typhimurium is controlled by a transcription attenuation mechanism. Four adjacent leucine codons within a 160-nucleotide leu leader RNA are thought to play a central role in this mechanism. Three of the four codons are CUA, a rarely used leucine codon within enteric bacteria. To determine whether the nature of the leucine codon affects the regulation of the leucine operon, we used oligonucleotide-directed mutagenesis to first convert one CUA of the leader to CUG and then convert all three CUA codons to CUG. CUG is the most frequently used leucine codon in enteric bacteria. A mutant having (CUA)2CUGCUC in place of (CUA)3CUC has an altered response to leucine limitation, requiring a slightly higher degree of limitation to effect derepression. Changing (CUA)3CUC to (CUG)3CUC has more dramatic effects upon operon expression. First, the basal level of expression is lowered to the point that the mutant grows more slowly than the parent in a minimal medium lacking leucine. Second, the response of the mutant to a leucine limitation is dramatically altered such that even a strong limitation elicits only a modest degree of derepression. If the mutant is grown under conditions of leucyl-tRNA limitation rather than leucine limitation, complete derepression can be achieved, but only at a much higher degree of limitation than for the wild-type operon. These results provide a clear-cut example of codon usage having a dramatic effect upon gene expression. PMID:3534884

  8. Orexin A attenuates palmitic acid-induced hypothalamic cell death.

    PubMed

    Duffy, Cayla M; Nixon, Joshua P; Butterick, Tammy A

    2016-09-01

    Palmitic acid (PA), an abundant dietary saturated fatty acid, contributes to obesity and hypothalamic dysregulation in part through increase in oxidative stress, insulin resistance, and neuroinflammation. Increased production of reactive oxygen species (ROS) as a result of PA exposure contributes to the onset of neuronal apoptosis. Additionally, high fat diets lead to changes in hypothalamic gene expression profiles including suppression of the anti-apoptotic protein B cell lymphoma 2 (Bcl-2) and upregulation of the pro-apoptotic protein B cell lymphoma 2 associated X protein (Bax). Orexin A (OXA), a hypothalamic peptide important in obesity resistance, also contributes to neuroprotection. Prior studies have demonstrated that OXA attenuates oxidative stress induced cell death. We hypothesized that OXA would be neuroprotective against PA induced cell death. To test this, we treated an immortalized hypothalamic cell line (designated mHypoA-1/2) with OXA and PA. We demonstrate that OXA attenuates PA-induced hypothalamic cell death via reduced caspase-3/7 apoptosis, stabilization of Bcl-2 gene expression, and reduced Bax/Bcl-2 gene expression ratio. We also found that OXA inhibits ROS production after PA exposure. Finally, we show that PA exposure in mHypoA-1/2 cells significantly reduces basal respiration, maximum respiration, ATP production, and reserve capacity. However, OXA treatment reverses PA-induced changes in intracellular metabolism, increasing basal respiration, maximum respiration, ATP production, and reserve capacity. Collectively, these results support that OXA protects against PA-induced hypothalamic dysregulation, and may represent one mechanism through which OXA can ameliorate effects of obesogenic diet on brain health. PMID:27449757

  9. Hypocretin/orexin loss changes the hypothalamic immune response.

    PubMed

    Tanaka, Susumu; Takizawa, Nae; Honda, Yoshiko; Koike, Taro; Oe, Souichi; Toyoda, Hiromi; Kodama, Tohru; Yamada, Hisao

    2016-10-01

    Hypocretin, also known as orexin, maintains the vigilance state and regulates various physiological processes, such as arousal, sleep, food intake, energy expenditure, and reward. Previously, we found that when wild-type mice and hypocretin/ataxin-3 littermates (which are depleted of hypothalamic hypocretin-expressing neurons postnatally) were administered lipopolysaccharide (LPS), the two genotypes exhibited significant differences in their sleep/wake cycle, including differences in the degree of increase in sleep periods and in recovery from sickness behaviour. In the present study, we examined changes in the hypothalamic vigilance system and in the hypothalamic expression of inflammatory factors in response to LPS in hypocretin/ataxin-3 mice. Peripheral immune challenge with LPS affected the hypothalamic immune response and vigilance states. This response was altered by the loss of hypocretin. Hypocretin expression was inhibited after LPS injection in both hypocretin/ataxin-3 mice and their wild-type littermates, but expression was completely abolished only in hypocretin/ataxin-3 mice. Increases in the number of histidine decarboxylase (HDC)-positive cells and in Hdc mRNA expression were found in hypocretin/ataxin-3 mice, and this increase was suppressed by LPS. Hypocretin loss did not impact the change in expression of hypothalamic inflammatory factors in response to LPS, except for interferon gamma and colony stimulating factor 3. The number of c-Fos-positive/HDC-positive cells in hypocretin/ataxin-3 mice administered LPS injections was elevated, even during the rest period, in all areas, suggesting that there is an increase in the activity of histaminergic neurons in hypocretin/ataxin-3 mice following LPS injection. Taken together, our results suggest a novel role for hypocretin in the hypothalamic response to peripheral immune challenge. Our findings contribute to the understanding of the pathophysiology of narcolepsy. PMID:27318095

  10. Glucose and leucine kinetics in idiopathic ketotic hypoglycaemia

    PubMed Central

    Bodamer, O A; Hussein, K; Morris, A A; Langhans, C‐D; Rating, D; Mayatepek, E; Leonard, J V

    2006-01-01

    Aims To investigate glucose and leucine kinetics in association with metabolic and endocrine investigations in children with ketotic hypoglycaemia (KH) in order to elucidate the underlying pathophysiology. Methods Prospective interventional study using stable isotope tracer in nine children (mean age 4.23 years, range 0.9–9.8 years; seven males) with KH and 11 controls (mean age 4.57 years, range 0.16–12.3 years; four males). Results Plasma insulin levels were significantly lower in KH compared to subjects in the non‐KH group. Plasma ketone body levels were significantly higher in KH than in non‐KH. Basal metabolic rate was significantly higher in subjects with KH (45.48±7.41 v 31.81±6.72 kcal/kg/day) but the respiratory quotients were similar in both groups (KH v non‐KH, 0.84±0.05 v 0.8±0.04. Leucine oxidation rates were significantly lower in children with KH (12.25±6.25 v 31.96±8.59 μmol/kg/h). Hepatic glucose production rates were also significantly lower in KH (3.84±0.46 v 6.6±0.59 mg/kg/min). Conclusions KH is caused by a failure to sustain hepatic glucose production rather than by increased glucose oxidation rates. Energy demand is significantly increased, whereas leucine oxidation is reduced. PMID:16443613

  11. Role of renal D-amino-acid oxidase in pharmacokinetics of D-leucine.

    PubMed

    Hasegawa, Hiroshi; Matsukawa, Takehisa; Shinohara, Yoshihiko; Konno, Ryuichi; Hashimoto, Takao

    2004-07-01

    d-Amino acids are now recognized to be widely present in mammals. Renal d-amino-acid oxidase (DAO) is associated with conversion of d-amino acids to the corresponding alpha-keto acids, but its contribution in vivo is poorly understood because the alpha-keto acids and/or l-amino acids formed are indistinguishable from endogenous compounds. First, we examined whether DAO is indispensable for conversion of d-amino acids to their alpha-keto acids by using the stable isotope tracer technique. After a bolus intravenous administration of d-[(2)H(7)]leucine to mutant mice lacking DAO activity (ddY/DAO(-)) and normal mice (ddY/DAO(+)), elimination of d-[(2)H(7)]leucine and formation of alpha-[(2)H(7)]ketoisocaproic acid ([(2)H(7)]KIC) and l-[(2)H(7)]leucine in plasma were determined. The ddY/DAO(-) mice, in contrast to ddY/DAO(+) mice, failed to convert d-[(2)H(7)]leucine to [(2)H(7)]KIC and l-[(2)H(7)]leucine. This result clearly revealed that DAO was indispensable for the process of chiral inversion of d-leucine. We further investigated the effect of renal mass reduction by partial nephrectomy on elimination of d-[(2)H(7)]leucine and formation of [(2)H(7)]KIC and l-[(2)H(7)]leucine. Renal mass reduction slowed down the elimination of d-[(2)H(7)]leucine. The fraction of conversion of d-[(2)H(7)]leucine to [(2)H(7)]KIC in sham-operated rats was 0.77, whereas that in five-sixths-nephrectomized rats was 0.25. The elimination behavior of d-[(2)H(7)]leucine observed in rats suggested that kidney was the principal organ responsible for converting d-leucine to KIC. PMID:15026304

  12. Effects of leucine supplemented diet on intestinal absorption in tumor bearing pregnant rats

    PubMed Central

    Ventrucci, Gislaine; de Mello, Maria Alice Roston; Gomes-Marcondes, Maria Cristina Cintra

    2002-01-01

    Background It is known that amino acid oxidation is increased in tumor-bearing rat muscles and that leucine is an important ketogenic amino acid that provides energy to the skeletal muscle. Methods To evaluate the effects of a leucine supplemented diet on the intestinal absorption alterations produced by Walker 256, growing pregnant rats were distributed into six groups. Three pregnant groups received a normal protein diet (18% protein): pregnant (N), tumor-bearing (WN), pair-fed rats (Np). Three other pregnant groups were fed a diet supplemented with 3% leucine (15% protein plus 3% leucine): leucine (L), tumor-bearing (WL) and pair-fed with leucine (Lp). Non pregnant rats (C), which received a normal protein diet, were used as a control group. After 20 days, the animals were submitted to intestinal perfusion to measure leucine, methionine and glucose absorption. Results Tumor-bearing pregnant rats showed impairment in food intake, body weight gain and muscle protein content, which were less accentuated in WL than in WN rats. These metabolic changes led to reduction in both fetal and tumor development. Leucine absorption slightly increased in WN group. In spite of having a significant decrease in leucine and methionine absorption compared to L, the WL group has shown a higher absorption rate of methionine than WN group, probably due to the ingestion of the leucine supplemented diet inducing this amino acid uptake. Glucose absorption was reduced in both tumor-bearing groups. Conclusions Leucine supplementation during pregnancy in tumor-bearing rats promoted high leucine absorption, increasing the availability of the amino acid for neoplasic cells and, mainly, for fetus and host utilization. This may have contributed to the better preservation of body weight gain, food intake and muscle protein observed in the supplemented rats in relation to the non-supplemented ones. PMID:11955290

  13. 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. PMID

  14. 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.

  15. 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. PMID:25668019

  16. 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.

  17. 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

  18. Exogenous valine reduces conversion of leucine to 3-methyl-1-butanol in Saccharomyces cerevisiae

    SciTech Connect

    Bigelis, R.; Weir, P.D.; Jones, R.R.M.; Umbarger, H.E.

    1983-02-01

    Mutant strains of the yeast Saccharomyces cerevisiae that require branched-chain amino acids must be supplemented with large concentrations (up to 10 mM) of these amino acids to satisfy their nutritional requirements. The utilization of one branched-chain amino acid, leucine, was examined in several leul strains of yeast grown aerobically in a glucose-ammonium salts minimal medium containing a limiting concentration (0.2 mM) of leucine. In this medium, the leucine requirement of the auxotrophic strains could be reduced by valine, another branched-chain amino acid. Increasing the valine concentration increased the cell yields of cultures and also reduced the levels of 3-methyl-1-butanol detected in the medium by gas chromatography. The concentration of 3-methyl-1-butanol was reduced from 122.0 to 48.9 ..mu..M when 5.0 mM valine was supplemented to limiting-leucine cultures. The amino acids isoleucine, threonine, norleucine, norvaline, ..cap alpha..-amino-butyrate, alanine, and glycine also spared the leucine requirement of leucine auxotrophs, most likely because they resemble leucine and competed for its uptake. We propose that leucine analogs restrict the entry and degradation of leucine and thus reduce its conversion to 3-methyl-1-butanol, a major component of fuel oil.

  19. Failure of dietary leucine to influence the tryptophan-niacin pathway in the chicken.

    PubMed

    Penz, A M; Clifford, A J; Rogers, Q R; Kratzer, F H

    1984-01-01

    Three experiments were conducted with young chicks to determine whether dietary leucine affects the conversion of tryptophan to niacin. Either tryptophan or niacin improved growth and reduced perosis when chicks were fed a purified diet marginal in tryptophan and deficient in niacin. Addition of 4.8% L-leucine to the diet did not alter the growth and perosis prevention response obtained with tryptophan. Liver weight was slightly increased by the addition of 5.4% L-leucine to the diet. Plasma insulin was slightly reduced by leucine and by isoleucine and valine. Picolinic carboxylase in the kidney was reduced in chicks fed 0.2% tryptophan with no niacin and was also reduced when isoleucine and valine were added to the diets. Liver picolinic carboxylase activity was not influenced by diet. Plasma isoleucine and valine were reduced by the addition of leucine to the diet and were increased again when isoleucine and valine were added to the diet. Plasma leucine was increased by the addition of leucine but was not altered by valine and isoleucine. Plasma tryptophan was not influenced by dietary supplements of leucine or isoleucine and valine. The results show that in the chick there is no evidence for an effect of leucine on the tryptophan to niacin pathway. PMID:6693983

  20. The thermodynamic characteristics of complex formation between calcium ions and L-leucine in aqueous solution

    NASA Astrophysics Data System (ADS)

    Kurochkin, V. Yu.; Chernikov, V. V.; Orlova, T. D.

    2011-04-01

    Complex formation of L-leucine with calcium ions in aqueous solution was studied by potentiometric titration at 298.15 K and ionic strength values I = 0.5, 1.0, and 1.5 (KNO3). The formation of the CaL+ and CaHL2+ complex particles was established and their stability constants were determined. The enthalpies of protolytic equilibria of leucine and formation of calcium ion complexes with leucine were determined calorimetrically at 298.15 K and I = 0.5 (KNO3). The thermodynamic characteristics of complex formation between calcium ions and L-leucine were calculated.

  1. 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. PMID:10601206

  2. Leucine Transport in Cells Isolated from Cold-Hardened and Nonhardened Winter Rye 1

    PubMed Central

    Barran, Leslie R.; Singh, Jas

    1982-01-01

    The properties of the leucine transport systems of cells isolated from dark-grown cold-hardened and nonhardened winter rye (Secale cereale L. cv. Puma) epicotyls were remarkably similar. After 1 hour of incubation, leucine was accumulated in the cells 80- to 100-fold above that of the external medium, but the transported leucine was not metabolized. Approximately one-third of the accumulated leucine was present in the vacuole after 40 minutes of incubation. At 25°C, efflux of leucine from the vacuole was 6 to 10 times slower than it was from the cytoplasm, while at 5°C efflux from the cells was inhibited. The apparent Km and Vmax for leucine uptake for both types of cells were of the order of 20 to 60 micromolar and 0.5 to 1.3 nanomoles per minute per 106 cells. The pH and temperature optima for both types of cells were 5 and 25°C, respectively. The leucine transport system for these cells was relatively specific for amino acids lacking either bulky or charged groups on the amino acid side chains. Arrhenius plots for leucine uptake by hardened and nonhardened cells showed discontinuities at 13°C, and the energies of activation were similar. The results suggests that biochemical changes which occur in rye cells upon cold hardening did not result in an observable perturbation of the properties of the leucine transport system. PMID:16662298

  3. 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. PMID:26607469

  4. 11 beta-Hydroxysteroid dehydrogenase activity in hypothalamic obesity.

    PubMed

    Tiosano, Dov; Eisentein, Israel; Militianu, Daniela; Chrousos, George P; Hochberg, Ze'ev

    2003-01-01

    After extensive suprasellar operations for hypothalamic tumor removal, some patients develop Cushing-like morbid obesity while they receive replacement doses of glucocorticoids. In this study, we examined the hypothesis that target tissue conversion of inactive 11-ketosteroids to active 11 beta-OH glucocorticoids might explain the obesity of some patients with hypothalamic lesions. Toward this aim, we studied 10 patients with hypothalamic obesity and secondary adrenal insufficiency and 6 control Addisonian patients while they were on glucocorticoid replacement therapy. Pituitary hormone deficiencies were replaced when medically indicated. Twenty-four-hour urine was collected after a single oral dose of 12 mg/m(2) hydrocortisone acetate. The ratios of free and conjugated cortisol (F) to cortisone (E) and their metabolites, [tetrahydrocortisol (THF)+5 alpha THF]/tetrahyrdocortisone (THE), dihydrocortisols/dihydrocortisones, cortols/cortolones, and (F+E)/(THF+THE+5 alpha THF), were considered to represent 11 beta-hydroxysteroid dehydrogenase (HSD) activity. The 11-OH/11-oxo ratios were significantly higher in the urine of patients with hypothalamic obesity. The 11-OH/11-oxo ratios, however, did not correlate with the degree of obesity, yet a significant correlation was found between conjugated F/E and the ratio of visceral fat to sc fat measured by computerized tomography at the umbilical level. The consequence of increased 11 beta-HSD1 activity and the shift of the interconversion toward cortisol may contribute to the effects of the latter in adipose tissue. We propose that deficiency of hypothalamic messengers after surgical injury induces a paracrine/autocrine effect of enhanced glucocorticoid activity due to up-regulated 11 beta-HSD1 activity. PMID:12519880

  5. Impaired hypothalamic mTOR activation in the adult rat offspring born to mothers fed a low-protein diet.

    PubMed

    Guzmán-Quevedo, Omar; Da Silva Aragão, Raquel; Pérez García, Georgina; Matos, Rhowena J B; de Sa Braga Oliveira, André; Manhães de Castro, Raul; Bolaños-Jiménez, Francisco

    2013-01-01

    Several epidemiological and experimental studies have clearly established that maternal malnutrition induces a high risk of developing obesity and related metabolic diseases in the offspring. To determine if altered nutrient sensing might underlie this enhanced disease susceptibility, here we examined the effects of perinatal protein restriction on the activation of the nutrient sensor mTOR in response to acute variations in the nutritional status of the organism. Female Wistar rats were fed isocaloric diets containing either 17% protein (control) or 8% protein (PR) throughout pregnancy and lactation. At weaning offspring received standard chow and at 4 months of age the effects of fasting or fasting plus re-feeding on the phosphorylation levels of mTOR and its downstream target S6 ribosomal protein (rpS6) in the hypothalamus were assessed by immuno-fluorescence and western blot. Under ad libitum feeding conditions, PR rats exhibited decreased mTOR and rpS6 phosphorylation in the arcuate (ARC) and ventromedial (VMH) hypothalamic nuclei. Moreover, the phosphorylation of mTOR and rpS6 in these hypothalamic nuclei decreased with fasting in control but not in PR animals. Conversely, PR animals exhibited enhanced number of pmTOR imunostained cells in the paraventricular nucleus (PVN) and fasting decreased the activation of mTOR in the PVN of malnourished but not of control rats. These alterations occurred at a developmental stage at which perinatally-undernourished animals do not show yet obesity or glucose intolerance. Collectively, our observations suggest that altered hypothalamic nutrient sensing in response to an inadequate foetal and neonatal energetic environment is one of the basic mechanisms of the developmental programming of metabolic disorders and might play a causing role in the development of the metabolic syndrome induced by malnutrition during early life. PMID:24040371

  6. 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

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

    PubMed

    Lee, Jun Hee; Cho, Uhn-Soo; Karin, Michael

    2016-01-01

    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. PMID:27273098

  8. TNFα increases hypothalamic PTP1B activity via the NFκB pathway in rat hypothalamic organotypic cultures.

    PubMed

    Ito, Yoshihiro; Banno, Ryoichi; Hagimoto, Shigeru; Ozawa, Yoshiharu; Arima, Hiroshi; Oiso, Yutaka

    2012-02-10

    In obesity, levels of tumor necrosis-factor α (TNFα) are well known to be elevated in adipose tissues or serum, and a high-fat diet (HFD) reportedly increases TNFα expression in the hypothalamus. The expression levels of hypothalamic protein tyrosine phosphatase 1B (PTP1B), a negative regulator of leptin and insulin signaling, are also elevated by HFD, and several lines of evidence support a relationship between TNFα and PTP1B. It remains unclear however how TNFα acts locally in the hypothalamus to regulate hypothalamic PTP1B expression and activity. In this study, we examined whether TNFα can regulate PTP1B expression and activity using rat hypothalamic organotypic cultures. Incubation of cultures with TNFα resulted in increases in mRNA expression, protein levels and activity of PTP1B in a dose- and time-dependent manner, respectively compared with controls. TNFα-induced PTP1B protein levels were not influenced by co-incubation with the sodium channel blocker tetrodotoxin, indicating that the action of TNFα is independent of action potentials. TNFα also increased phosphorylation of p65, a subunit of nuclear factor-κB (NFκB), in a dose- and time-dependent manner. While incubation with inhibitors of NFκB did not affect basal levels of either p65 phosphorylation or PTP1B expression, it markedly suppressed both TNFα-induced p65 phosphorylation and PTP1B expression to almost basal levels. These data suggest that TNFα acts on the hypothalamus to increase hypothalamic PTP1B expression and activity via the NFκB pathway, and that TNFα-mediated induction of NFκB in the hypothalamus may cause leptin and insulin resistance in the hypothalamus by increasing hypothalamic PTP1B activity. PMID:22166493

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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). ...

  11. 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. PMID:26784991

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  14. 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

  15. Hypothalamic and dietary control of temperature-mediated longevity

    PubMed Central

    Tabarean, Iustin; Morrison, Brad; Marcondes, Maria Cecilia; Bartfai, Tamas; Conti, Bruno

    2009-01-01

    Temperature is an important modulator of longevity and aging in both poikilotherms and homeotherm animals. In homeotherms, temperature homeostasis is regulated primarily in the preoptic area (POA) of the hypothalamus. This region receives and integrates peripheral, central and environmental signals and maintains a nearly constant core body temperature (Tcore) by regulating the autonomic and hormonal control of heat production and heat dissipation. Temperature sensitive neurons found in the POA are considered key elements of the neuronal circuitry modulating these effects. Nutrient homeostasis is also a hypothalamically regulated modulator of aging as well as one of the signals that can influence Tcore in homeotherms. Investigating the mechanisms of the regulation of nutrient and temperature homeostasis in the hypothalamus is important to understand how these two elements of energy homeostasis influence longevity and aging as well as how aging can affect hypothalamic homeostatic mechanisms. PMID:19631766

  16. 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

  17. [Neurovegetative and hypothalamic syndromes in children with infantile cerebral palsy].

    PubMed

    Maslova, O I; Lebedev, B V

    1980-01-01

    An analysis of the neuropsychic and vegetative status of 108 children aged 3 months to 7 years suffering from infantile cerebral paralysis has shown that in a great part of the patients a neurovegetative or hypothalamic syndrome can be additionally specified. An analysis of the totality of the background vegetative characteristics shows that the effection of this division of the nervous system is of a mixed character. Different direction of the vegetative reactions, i.e. sympathetic or parasympathetic, can be noted in different forms of the paralysis. The neurovegetative syndrome can be discerned in children with a noticeable psychic defect, while the hypothalamic one in children with a good psychic development. PMID:7435028

  18. Dissecting the hypothalamic pathways that underlie innate behaviors.

    PubMed

    Zha, Xi; Xu, Xiaohong

    2015-12-01

    Many complex behaviors that do not require learning are displayed and are termed innate. Although traditionally the subject matter of ethology, innate behaviors offer a unique entry point for neuroscientists to dissect the physiological mechanisms governing complex behaviors. Since the last century, converging evidence has implicated the hypothalamus as the central brain area that controls innate behaviors. Recent studies using cutting-edge tools have revealed that genetically-defined populations of neurons residing in distinct hypothalamic nuclei and their associated neural pathways regulate the initiation and maintenance of diverse behaviors including feeding, sleep, aggression, and parental care. Here, we review the newly-defined hypothalamic pathways that regulate each innate behavior. In addition, emerging general principles of the neural control of complex behaviors are discussed. PMID:26552801

  19. Hypothalamic and dietary control of temperature-mediated longevity.

    PubMed

    Tabarean, Iustin; Morrison, Brad; Marcondes, Maria Cecilia; Bartfai, Tamas; Conti, Bruno

    2010-01-01

    Temperature is an important modulator of longevity and aging in both poikilotherms and homeotherm animals. In homeotherms, temperature homeostasis is regulated primarily in the preoptic area (POA) of the hypothalamus. This region receives and integrates peripheral, central and environmental signals and maintains a nearly constant core body temperature (T(core)) by regulating the autonomic and hormonal control of heat production and heat dissipation. Temperature sensitive neurons found in the POA are considered key elements of the neuronal circuitry modulating these effects. Nutrient homeostasis is also a hypothalamically regulated modulator of aging as well as one of the signals that can influence T(core) in homeotherms. Investigating the mechanisms of the regulation of nutrient and temperature homeostasis in the hypothalamus is important to understanding how these two elements of energy homeostasis influence longevity and aging as well as how aging can affect hypothalamic homeostatic mechanisms. PMID:19631766

  20. Leucine-rich glioma-inactivated protein 1 antibody encephalitis

    PubMed Central

    Mayasi, Yunis; Takhtani, Deepak

    2014-01-01

    Objective: To describe a case of leucine-rich glioma-inactivated protein 1 (LGI1) antibody–associated encephalitis. Methods: The clinical and ancillary data and brain MRIs were gathered retrospectively by chart review. Relevant literature on similar cases was also reviewed. Results: The diagnosis of LGI1 antibody–associated autoimmune encephalitis was based on the typical clinical presentation of seizures, psychiatric symptoms, and memory loss as well as negative diagnostic testing for cancer; the diagnosis was confirmed by positive LGI1 antibody. The patient responded favorably to treatment with IV immunoglobulin and continues to do well. Conclusion: LGI1 antibody–associated encephalitis has increasingly been recognized as a primary autoimmune disorder with good prognosis and response to treatment. PMID:25520958

  1. Chiral conducting surfaces via electrochemical oxidation of L-leucine-oligothiophenes.

    PubMed

    McTiernan, Christopher D; Omri, Karim; Chahma, M'hamed

    2010-09-17

    Polythiophenes bearing a specific chiral center such as L-leucine have been prepared via the electrochemical oxidation of a series of L-leucine functionalized oligothiophenes (monothiophenes and terthiophenes). These oligothiophenes have been prepared through the condensation of L-leucine methyl ester and the corresponding thiophene monomers in the presence of hydroxybenzotriazole (HOBt) and N,N'-dicyclohexylcarbodiimide (DCC) followed by hydrolysis of the esters. The electroactive polymers are electrochemically stable and exhibit excellent adhesive properties on electrode surfaces (platinum, gold, and glassy carbon) as well as interesting optical properties in both doped and undoped states. Hydrogen bonds between a free amino acid (L-leucine, D-leucine, L-alanine, D-alanine, and D/L-alanine) and the L-leucine based polythiophenes (chiral conducting surface) were probed using cyclic voltammetry. Preliminary results show that the capacitive current of a modified L-leucine-polythiophene electrode decreases as a result of the formation of a hydrogen bond barrier on the surface of the chiral conducting surface accompanied with a shift of the oxidation potential. Cyclic voltammetry responses resulting from the interaction of the chiral conducting surface with L and Dfree amino acid isomers are similar. The formation of hydrogen bonds between the chiral conducting surfaces and the free amino acids was characterized by (1)H NMR. A chemical shift was observed for the N-H group in monomer 6 as a result of the hydrogen bond formation between the L-leucine methyl ester (D-leucine methyl ester, D/L-leucine methyl ester) and monomer 6. PMID:20718451

  2. 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

  3. Integrity of hypothalamic fibers and cognitive fatigue in multiple sclerosis.

    PubMed

    Hanken, Katrin; Eling, Paul; Kastrup, Andreas; Klein, Jan; Hildebrandt, Helmut

    2015-01-01

    Cognitive fatigue is a common and disabling symptom of multiple sclerosis (MS), but little is known about its pathophysiology. The present study investigated whether the posterior hypothalamus, which is considered as the waking center, is associated with MS-related cognitive fatigue. We analyzed the integrity of posterior hypothalamic fibers in 49 patients with relapsing-remitting MS and 14 healthy controls. Diffusion tensor imaging (DTI) parameters were calculated for fibers between the posterior hypothalamus and, respectively, the mesencephalon, pons and prefrontal cortex. In addition, DTI parameters were computed for fibers between the anterior hypothalamus and these regions and for the corpus callosum. Cognitive fatigue was assessed using the Fatigue Scale for Motor and Cognitive Functions. Analyses of variance with repeated measures were performed to investigate the impact of cognitive fatigue on diffusion parameters. Cognitively fatigued patients (75.5%) showed a significantly lower mean axial and radial diffusivity for fibers between the posterior hypothalamus and the mesencephalon than cognitively non-fatigued patients (Group(⁎)Target area(⁎)Diffusion orientation: F=4.047; p=0.023). For fibers of the corpus callosum, MS patients presented significantly higher axial and radial diffusivity than healthy controls (Group(⁎)Diffusion orientation: F=9.904; p<0.001). Depressive mood, used as covariate, revealed significant interaction effects for anterior hypothalamic fibers (Target area(⁎)Diffusion orientation(⁎)Depression: F=5.882; p=0.021; Hemisphere(⁎)Diffusion orientation(⁎) Depression: F=8.744; p=0.008). Changes in integrity of fibers between the posterior hypothalamus and the mesencephalon appear to be associated with MS-related cognitive fatigue. These changes might cause an altered modulation of hypothalamic centers responsible for wakefulness. Furthermore, integrity of anterior hypothalamic fibers might be related to depression in MS. PMID

  4. Co-existent eosinophilic gastroenteritis and hypothalamic-pituitary dysfunction.

    PubMed Central

    Haeney, M. R.; Wilson, R. J.

    1977-01-01

    A case of eosinophilic gastroenteritis in a 42-year-old man is described. The patient had diarrhoea, faecal blood loss, a protein-losing enteropathy, malabsorption of fat, xylose and vitamin B12. Co-existent hypopituitarism, diabetes insipidus and hypothalamic dysfunction was demonstrated. Complete clinical recovery occurred with pituitary replacement therapy alone. The association of this endocrine abnormality with the picture of eosinophilic gastroenteritis has not previously been described. Images Fig. 1 PMID:882484

  5. Physiology of the Hypothalamic Pituitary Gonadal Axis in the Male.

    PubMed

    Corradi, Patricia Freitas; Corradi, Renato B; Greene, Loren Wissner

    2016-05-01

    Testosterone synthesis and male fertility are the results of the perfect coordination of the hypothalamic-pituitary-gonadal axis. A negative feedback finely controls the secretion of hormones at the 3 levels. Congenital or acquired disturbance at any level leads to an impairment of reproductive function and the clinical syndrome of hypogonadism. In some cases, this condition is reversible. Once the diagnosis is made, testosterone replacement therapy is the standard therapy; however, novel therapies may improve spermatogenesis while elevating testosterone levels. PMID:27132572

  6. 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.

  7. 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.

  8. Effect of cancer treatment on hypothalamic-pituitary function.

    PubMed

    Crowne, Elizabeth; Gleeson, Helena; Benghiat, Helen; Sanghera, Paul; Toogood, Andrew

    2015-07-01

    The past 30 years have seen a great improvement in survival of children and young adults treated for cancer. Cancer treatment can put patients at risk of health problems that can develop many years later, most commonly affecting the endocrine system. Patients treated with cranial radiotherapy often develop dysfunction of the hypothalamic-pituitary axis. A characteristic pattern of hormone deficiencies develops over several years. Growth hormone is disrupted most often, followed by gonadal, adrenal, and thyroid hormones, leading to abnormal growth and puberty in children, and affecting general wellbeing and fertility in adults. The severity and rate of development of hypopituitarism is determined by the dose of radiotherapy delivered to the hypothalamic-pituitary axis. Individual growth hormone deficiencies can develop after a dose as low as 10 Gy, whereas multiple hormone deficiencies are common after 60 Gy. New techniques in radiotherapy aim to reduce the effect on the hypothalamic-pituitary axis by minimising the dose received. Patients taking cytotoxic drugs do not often develop overt hypopituitarism, although the effect of radiotherapy might be enhanced. The exception is adrenal insufficiency caused by glucocorticosteroids which, although transient, can be life-threatening. New biological drugs to treat cancer can cause autoimmune hypophysitis and hypopituitarism; therefore, oncologists and endocrinologists should be vigilant and work together to optimise patient outcomes. PMID:25873572

  9. 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. PMID:26136135

  10. 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

  11. 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. PMID:25449399

  12. Hypothalamic leptin action is mediated by histone deacetylase 5.

    PubMed

    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

  13. Role of Insulin in the Regulation of Leucine Kinetics in the Conscious Dog

    PubMed Central

    Abumrad, Naji N.; Jefferson, L. S.; Rannels, S. R.; Williams, P. E.; Cherrington, A. D.; Lacy, W. W.

    1982-01-01

    To study the effect of insulin on leucine kinetics, three groups of conscious dogs were studied after an overnight fast (16-18 h). One, saline-infused group (n = 5), served as control. The other two groups were infused with somatostatin and constant replacement amount of glucagon; one group (n = 6) received no insulin replacement, to produce acute insulin deficiency, and the other (n = 6) was constantly replaced with 600 μU/kg per min insulin, to produce twice basal hyperinsulinemia. Hepatic and extrahepatic splanchnic (gut) balance of leucine and α-ketoisocaproate (KIC) were calculated using the arteriovenous difference technique. l,4,5,[3H]Leucine was used to measure the rates (micromoles per kilogram per minute) of appearance (Ra) and disappearance (Rd), and clearance (Cl) of plasma leucine (milliliters per kilogram per minute). Saline infusion for 7 h resulted in isotopic steady state, where Ra and Rd were equal (3.2±0.2 μmol/kg per min). Acute insulin withdrawal of 4-h duration caused the plasma leucine to increase by 40% (P < 0.005). This change was caused by a decrease in the outflow of leucine (Cl) from the plasma, since Ra did not change. The net hepatic release of the amino acid (0.24±0.03 μmol/kg per min) did not change significantly; the arterio-deep femoral venous differences of leucine (−10±1 μmol/liter) and KIC (−12±2 μmol/liter) did not change significantly indicating net release of the amino and ketoacids across the hindlimb. Selective twice basal hyperinsulinemia resulted in a 36% drop in plasma leucine (from control levels of 128±8 to 82±7 μmol/liter, P < 0.005) within 4 h. This was accompanied by a 15% reduction in Ra and a 56% rise in clearance (P < 0.001, both). Net hepatic leucine production and net release of leucine and KIC across the hindlimb fell markedly. These studies indicate that physiologic changes in circulating insulin levels result in a differential dose-dependent effect on total body leucine metabolism in the

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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....

  16. Multiple hypothalamic cell populations encoding distinct visual information

    PubMed Central

    Brown, Timothy M; Wynne, Jonathan; Piggins, Hugh D; Lucas, Robert J

    2011-01-01

    Environmental illumination profoundly influences mammalian physiology and behaviour through actions on a master circadian oscillator in the suprachiasmatic nuclei (SCN) and other hypothalamic nuclei. The retinal and central mechanisms that shape daily patterns of light-evoked and spontaneous activity in this network of hypothalamic cells are still largely unclear. Similarly, the exact nature of the sensory information conveyed by such cells is unresolved. Here we set out to address these issues, through multielectrode recordings from the hypothalamus of red cone knockin mice (Opn1mwR). With this powerful mouse model, the photoreceptive origins of any response can be readily identified on the basis of their relative sensitivity to short and long wavelength light. Our experiments revealed that the firing pattern of many hypothalamic cells was influenced by changes in light levels and/or according to the steady state level of illumination. These ‘contrast’ and ‘irradiance’ responses were driven primarily by cone and melanopsin photoreceptors respectively, with rods exhibiting a much more subtle influence. Individual hypothalamic neurons differentially sampled from these information streams, giving rise to four distinct response types. The most common response phenotype in the SCN itself was sustained activation. Cells with this behaviour responded to all three photoreceptor classes in a manner consistent with their distinct contributions to circadian photoentrainment. These ‘sustained’ cells were also unique in our sample in expressing circadian firing patterns with highest activity during the mid projected day. Surprisingly, we also found a minority of SCN neurons that lacked the melanopsin-derived irradiance signal and responded only to light transitions, allowing for the possibility that rod–cone contrast signals may be routed to SCN output targets without influencing neighbouring circadian oscillators. Finally, an array of cells extending throughout

  17. Structure and dissolution of L-leucine-coated salbutamol sulphate aerosol particles.

    PubMed

    Raula, Janne; Seppälä, Jukka; Malm, Jari; Karppinen, Maarit; Kauppinen, Esko I

    2012-06-01

    L-Leucine formed different crystalline coatings on salbutamol sulphate aerosol particles depending on the saturation conditions of L-leucine. The work emphasizes a careful characterization of powders where structural compartments such as crystal size and particle coating may affect the performance of drug when administered. The sublimation of L-leucine from the aerosol particles took place 90°C lower temperature than the bulk L-leucine which was attributed to result from the sublimation of L-leucine from nano-sized crystalline domains. The dissolution slowed down and initial dissolution rate decreased with increasing L-leucine content. Decreasing crystalline domains to nano-scale improve heat and mass transfer which was observed as the lowered decomposition temperature of the drug salbutamol sulphate and the sublimation temperature of surface material L-leucine as well as the altered dissolution characteristics of the drug. The structure of the coated drug particles was studied by means of thermal analysis techniques (DSC and TG), and the dissolution of salbutamol sulphate was studied as an on-line measurement in a diffusion cell. PMID:22562614

  18. 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. PMID:17682820

  19. 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

    2014-10-01

    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

  20. 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

  1. 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

  2. Determination of the safety of leucine supplementation in healthy elderly men.

    PubMed

    Rasmussen, Betina; Gilbert, Erin; Turki, Abrar; Madden, Kenneth; Elango, Rajavel

    2016-07-01

    Leucine, a branched-chain amino acid (BCAA), has been shown to stimulate muscle protein synthesis, and thus has been proposed to prevent age-related muscle atrophy (sarcopenia). Therefore, leucine supplementation may have potential benefits in elderly populations to preserve muscle mass. The tolerable upper intake level (UL) for leucine intake in young men has recently been determined to be 500 mg kg(-1) day(-1), and increases in blood ammonia concentrations were seen at intake levels above 500 mg kg(-1) day(-1); the UL for leucine in elderly is unknown. The objective of the current study was to determine the safety of leucine supplementation in healthy elderly men. Six healthy elderly men (72.2 ± 3.5 years) received graded stepwise increases in leucine intakes ranging from 50 to 750 mg kg(-1) day(-1), on eight separate study days. Plasma and urinary biochemical variables, including blood ammonia, and an oral primed-continuous protocol of L-1-(13)C-Leucine was performed. Blood ammonia concentrations above normal values (35 µmol/L) were observed at leucine intakes >550 mg kg(-1) day(-1). Leucine oxidation measured as a F(13)CO2 (rate of label tracer oxidation) increased with increasing leucine intakes and started to plateau after 450 mg kg(-1) day(-1). Two-phased linear regression analysis of the F(13)CO2 data revealed a breakpoint of 431 mg kg(-1) day(-1) (R (2) = 0.73), suggesting that the upper limit to oxidize leucine was reached at that point. Taking the data together the upper limit for leucine intake in healthy elderly could be set similar to young men at 500 mg kg(-1) day(-1) or ~35 g/day for an individual weighing 70 kg. PMID:27138628

  3. Transactivation and transformation by Myb are negatively regulated by a leucine-zipper structure.

    PubMed Central

    Kanei-Ishii, C; MacMillan, E M; Nomura, T; Sarai, A; Ramsay, R G; Aimoto, S; Ishii, S; Gonda, T J

    1992-01-01

    The negative regulatory domain of the c-myb protooncogene product (c-Myb) normally represses transcriptional activation by c-Myb. We show here that a leucine-zipper structure is a component of the negative regulatory domain, because its disruption markedly increases both the transactivating and transforming capacities of c-Myb. We also demonstrate that this leucine-zipper structure can interact with cellular proteins. Our results suggest that an inhibitor that suppresses transactivation binds to c-Myb through the leucine zipper and that c-Myb can be oncogenically activated by missense mutation. Images PMID:1557416

  4. 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

  5. Escherichia coli Lrp (Leucine-Responsive Regulatory Protein) Does Not Directly Regulate Expression of the leu Operon Promoter

    PubMed Central

    Landgraf, Jeffrey R.; Boxer, Jonathan A.; Calvo, Joseph M.

    1999-01-01

    Studies by R. Lin et al. (J. Bacteriol. 174:1948–1955, 1992) suggested that the Escherichia coli leu operon might be a member of the Lrp regulon. Their results were obtained with a leucine auxotroph; in leucine prototrophs grown in a medium lacking leucine, there was little difference in leu operon expression between lrp+ and lrp strains. Furthermore, when leuP-lacZ transcriptional fusions that lacked the leu attenuator were used, expression from the leu promoter varied less than twofold between lrp+ and lrp strains, irrespective of whether or not excess leucine was added to the medium. The simplest explanation of the observations of Lin et al. is that the known elevated leucine transport capacity of lrp strains (S. A. Haney et al., J. Bacteriol. 174:108–115, 1992) leads to very high intracellular levels of leucine for strains grown with leucine, resulting in the superattenuation of leu operon expression. PMID:10515950

  6. 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.

  7. 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

  8. Inhibition of cell growth by a hypothalamic peptide.

    PubMed Central

    Redding, T W; Schally, A V

    1982-01-01

    A fraction purified from acetic acid extracts of porcine hypothalami was found to contain significant antimitogenic activity when tested in normal and neoplastic cell lines. Addition of this hypothalamic material (1-100 micrograms/ml) to culture media significantly inhibited [3H]thymidine incorporation into cellular DNA in several cell lines. Amino acid incorporation into pituitary proteins and uridine incorporation into RNA were also significantly reduced by this factor(s). Addition to the culture media of this hypothalamic material at 5 micrograms/ml and 50 micrograms/ml per day decreased by 17% and 36%, respectively, cell numbers of 3T6 fibroblast cell cultures. Time-response curves showed that the inhibition of [3H]thymidine incorporation into DNA in 3T6 fibroblast cells begins within 2 hr after adding this fraction to the culture medium. The inhibitory action cannot be explained by a direct cytotoxic effect since 3T6 cells labeled with 51Cr and incubated for 6 hr in the presence of this hypothalamic fraction fail to show an increase in the release of 51Cr into the medium as compared with controls. Incubation with trypsin and chymotrypsin completely abolished the antimitogenic activity of this material and pepsin decreased it. This strongly suggests that the antimitogenic activity exhibited by this fraction is due to a polypeptide(s). These observations provide evidence for the presence in the mammalian hypothalamus of an antimitogenic peptide(s) that may be involved in the regulation of cell proliferation. PMID:6757925

  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. PMID:20926200

  10. Diurnal regulation of hypothalamic kisspeptin is disrupted during mouse pregnancy.

    PubMed

    Yap, Cassandra C; Wharfe, Michaela D; Mark, Peter J; Waddell, Brendan J; Smith, Jeremy T

    2016-06-01

    Kisspeptin, the neuropeptide product of the Kiss1 gene, is critical in driving the hypothalamic-pituitary-gonadal (HPG) axis. Kisspeptin neurons in the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (Arc) of the hypothalamus mediate differential effects, with the Arc regulating negative feedback of sex steroids and the AVPV regulating positive feedback, vital for the preovulatory surge and gated under circadian control. We aimed to characterize hypothalamic Kiss1 and Kiss1r mRNA expression in nonpregnant and pregnant mice, and investigate potential circadian regulation. Anterior and posterior hypothalami were collected from C57BL/6J mice at diestrus, proestrus, and days 6, 10, 14, and 18 of pregnancy, at six time points across 24h, for real-time PCR analysis of gene expression. Analysis confirmed that Kiss1 mRNA expression in the AVPV increased at ZT13 during proestrus, with a luteinizing hormone surge observed thereafter. No diurnal regulation was seen at diestrus or at any stage of pregnancy. Anterior hypothalamic Avp mRNA expression exhibited no diurnal variation, but Avpr1a peaked at 12:00h during proestrus, possibly reflecting the circadian input from the suprachiasmatic nucleus to AVPV Kiss1 neurons. Rfrp (Npvf) expression in the posterior hypothalamus did not demonstrate diurnal variation at any stage. Clock genes Bmal1 and Rev-erbα were strongly diurnal, but there was little change between diestrus/proestrus and pregnancy. Our data indicate the absence of the circadian input to Kiss1 in pregnancy, despite high gestational estradiol levels and normal clock gene expression, and may suggest a disruption of a kisspeptin-specific diurnal rhythm that operates in the nonpregnant state. PMID:27068699

  11. 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 lowerPomcbut higherAgrpmRNA 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 lateral

  12. 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

  13. [Hypothalamic hamartoma and gelastic crises. Apropos of 7 cases].

    PubMed

    Ponsot, G; Diebler, C; Plouin, P; Nardou, M; Dulac, O; Chaussain, J L; Arthuis, M

    1983-12-01

    Seven cases of hypothalamic hamartomas with gelastic seizures are reported. A precocious puberty was found in 4 cases. The normal neurologic examination and lack of sign of intracranial hypertension were in contrast with the severity of the epileptic seizures, of the mental impairment and of the behavioral disorders. The fact that the presenting symptom may be gelastic seizures is stressed. CT scan is the best means to assess the diagnosis and to follow the evolution of these tumors. Except for the management of the precocious puberty, the treatment is disappointing and neurosurgical indications are quite exceptional. PMID:6673679

  14. 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

  15. 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

  16. Leucine metabolism in rat liver after a bolus injection of endotoxin.

    PubMed

    Holecek, M; Sprongl, L; Tichý, M; Pecka, M

    1998-06-01

    To evaluate the contribution of hepatic tissue to alterations in the metabolism of proteins and the branched-chain amino acids (BCAA) leucine, isoleucine, and valine in systemic inflammatory response syndrome, we studied the changes of leucine metabolism in isolated perfused liver (IPL) of endotoxin-treated rats. Male albino rats were injected with the endotoxin of Salmonella enteritidis (5 mg x kg(-1)) or saline (control). Four hours later, leucine and ketoisocaproate (KIC) oxidation and incorporation into liver proteins were determined in IPL using the single-pass liver perfusion technique. L-[1-(14)C]leucine and alpha-keto[1-(14)C]isocaproic acid were used as a tracer in two separate experiments. Endotoxin treatment resulted in a decrease of plasma BCAA levels, an increase of leucine oxidation, and a decrease of KIC oxidation by IPL. Leucine incorporation into liver proteins was lower in endotoxin-treated rats, and we did not find measurable incorporation of the labeled carbon of KIC in liver proteins in either group of animals. The sum of individual amino acid concentrations in the effluent perfusate was higher in endotoxin-treated animals, although only leucine and phenylalanine increased significantly. The decrease in KIC oxidation indicates a decreased capacity of hepatic tissue to oxidize branched-chain ketoacids (BCKA). The increase in leucine oxidation by IPL of endotoxin-treated rats indicates an increase in BCAA aminotransferase activity. These changes demonstrate an important response of the body that enables the resynthesis of essential BCAA from their ketoanalogs delivered to the liver from peripheral tissues, particularly muscle. PMID:9627366

  17. 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. PMID:25648818

  18. 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. PMID:27010498

  19. 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. PMID:25060730

  20. 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. PMID:24098154

  1. 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

  2. LRR Conservation Mapping to Predict Functional Sites within Protein Leucine-Rich Repeat Domains

    PubMed Central

    Helft, Laura; Reddy, Vignyan; Chen, Xiyang; Koller, Teresa; Federici, Luca; Fernández-Recio, Juan; Gupta, Rishabh; Bent, Andrew

    2011-01-01

    Computational prediction of protein functional sites can be a critical first step for analysis of large or complex proteins. Contemporary methods often require several homologous sequences and/or a known protein structure, but these resources are not available for many proteins. Leucine-rich repeats (LRRs) are ligand interaction domains found in numerous proteins across all taxonomic kingdoms, including immune system receptors in plants and animals. We devised Repeat Conservation Mapping (RCM), a computational method that predicts functional sites of LRR domains. RCM utilizes two or more homologous sequences and a generic representation of the LRR structure to identify conserved or diversified patches of amino acids on the predicted surface of the LRR. RCM was validated using solved LRR+ligand structures from multiple taxa, identifying ligand interaction sites. RCM was then used for de novo dissection of two plant microbe-associated molecular pattern (MAMP) receptors, EF-TU RECEPTOR (EFR) and FLAGELLIN-SENSING 2 (FLS2). In vivo testing of Arabidopsis thaliana EFR and FLS2 receptors mutagenized at sites identified by RCM demonstrated previously unknown functional sites. The RCM predictions for EFR, FLS2 and a third plant LRR protein, PGIP, compared favorably to predictions from ODA (optimal docking area), Consurf, and PAML (positive selection) analyses, but RCM also made valid functional site predictions not available from these other bioinformatic approaches. RCM analyses can be conducted with any LRR-containing proteins at www.plantpath.wisc.edu/RCM, and the approach should be modifiable for use with other types of repeat protein domains. PMID:21789174

  3. 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

  4. Surgical excision of hypothalamic hamartoma in a twenty months old boy with precocious puberty

    PubMed Central

    Ghanta, Rajesh K.; Koti, Kalyan; Kongara, Srikanth; Meher, Gautham E.

    2011-01-01

    A twenty months old boy presented to our department with true precocious puberty due to hypothalamic hamartoma. Total surgical excision of pedunculated hypothalamic hamartoma was done successfully by the pterional trans-sylvian approach as he could not afford medical management. Patient had uneventful post-operative course with normalization of serum testosterone levels and regression of secondary sexual characters. PMID:22029036

  5. 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. PMID:26449471

  6. 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

  7. Diurnal variation in glucose and leucine metabolism in non-insulin-dependent diabetes.

    PubMed

    Umpleby, A M; Scobie, I N; Boroujerdi, M A; Carson, E R; Sonksen, P H

    1990-04-01

    Glucose and leucine metabolism were investigated in 5 poorly controlled non-insulin-dependent diabetics (NIDDM) following an i.v. injection of 3-[3H]glucose and 1-[14C]leucine in the morning and evening. In the morning glucose concentration (11.2 +/- 0.8 mmol/l) (mean +/- SEM) and production rate (14.2 +/- 1.3 mumol/min/kg) were significantly greater (P less than 0.001, P less than 0.05) and glucose metabolic clearance rate (MCR) (1.3 +/- 0.2 ml/min/kg) significantly lower (P less than 0.05) than in a group of control subjects. Glucose concentration was lower in the evening (P less than 0.05) as a result of a decrease in glucose production rate (P less than 0.05). Leucine concentration and production rate were not significantly different from normal but leucine oxidation rate was increased (P less than 0.05). There was no diurnal variation in leucine metabolism. Since leucine production is a measure of protein breakdown, the higher morning glucose production rate was not due to an increased supply of gluconeogenic precursors from protein catabolism. PMID:2190784

  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

    2016-01-01

    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

  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. Peripheral chemerin administration modulates hypothalamic control of feeding.

    PubMed

    Brunetti, Luigi; Orlando, Giustino; Ferrante, Claudio; Recinella, Lucia; Leone, Sheila; Chiavaroli, Annalisa; Di Nisio, Chiara; Shohreh, Rugia; Manippa, Fabio; Ricciuti, Adriana; Vacca, Michele

    2014-01-01

    Chemerin is a recently identified adipokine that is involved in the regulation of adipogenesis, energy metabolism, and inflammation. The aim of the present study was to investigate the role of chemerin on food intake, body weight and hypothalamic peptidergic and aminergic modulators which play a pivotal role in feeding regulation in rats. Male adult Wistar rats were intraperitoneally injected, daily for 17 days at 9.00am, with either vehicle (saline; N=12) or chemerin (8μg/kg; N=12) and (16μg/kg; N=12). Food intake was recorded 24h after each administration. Animals were sacrificed 24h after the last injection. Total RNA was extracted from hypothalami and reverse transcribed to evaluate gene expression of agouti-related peptide (AgRP), neuropeptide Y (NPY), orexin-A, corticotrophin releasing hormone (CRH), pro-opiomelanocortin (POMC) and cocaine and amphetamine-regulated transcript (CART). Furthermore, we evaluated the effect of chemerin on dopamine, norepinephrine and serotonin steady state concentrations in rat hypothalamus homogenate, and monoamine release from rat hypothalamic synaptosomes. Chemerin administration (8 and 16μg/kg) decreased both food intake and body weight compared to vehicle, possibly associated with a significant increase in serotonin synthesis and release, in the hypothalamus. On the other hand, the pattern of gene expression following chemerin administration indicates a minor role played by chemerin as a peripheral appetite-regulating signal. PMID:24269538

  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. Hypothalamic POMC neurons promote cannabinoid-induced feeding

    PubMed Central

    Koch, Marco; Varela, Luis; Kim, Jae Geun; Kim, Jung Dae; Hernandez, Francisco; Simonds, Stephanie E; Castorena, Carlos M; Vianna, Claudia R; Elmquist, Joel K; Morozov, Yury M; Rakic, Pasko; Bechmann, Ingo; Cowley, Michael A; Szigeti-Buck, Klara; Dietrich, Marcelo O; Gao, Xiao-Bing; Diano, Sabrina

    2015-01-01

    SUMMARY Hypothalamic pro-opiomelanocortin (POMC) neurons promote satiety. Cannabinoid receptor 1 (CB1R) is critical for central regulation of food intake. We interrogated whether CB1R-controlled feeding is paralleled by decreased activity of POMC neurons. Chemical promotion of CB1R activity increased feeding, and strikingly, CB1R activation also promoted neuronal activity of POMC cells. This paradoxical increase in POMC activity was crucial for CB1R-induced feeding, because Designer-Receptors-Exclusively-Activated-by-Designer-Drugs (DREADD)-mediated inhibition of POMC neurons diminished, while DREADD-mediated activation of POMC neurons enhanced CB1R-driven feeding. The Pomc gene encodes both the anorexigenic peptide, α-melanocyte-stimulating hormone (α-MSH), and the peptide, β-endorphin. CB1R activation selectively increased β-endorphin but not α-MSH release in the hypothalamus, and, systemic or hypothalamic administration of the opioid receptor antagonist, naloxone, blocked acute CB1R-induced feeding. These processes involved mitochondrial adaptations, which, when blocked, abolished CB1R-induced cellular responses and feeding. Together, these results unmasked a previously unsuspected role of POMC neurons in promotion of feeding by cannabinoids. PMID:25707796

  13. Leptin is an effective treatment for hypothalamic amenorrhea

    PubMed Central

    Chou, Sharon H.; Chamberland, John P.; Liu, Xiaowen; Matarese, Giuseppe; Gao, Chuanyun; Stefanakis, Rianna; Brinkoetter, Mary T.; Gong, Huizhi; Arampatzi, Kalliopi; Mantzoros, Christos S.

    2011-01-01

    Hypothalamic amenorrhea (HA) is associated with dysfunction of the hypothalamic-pituitary-peripheral endocrine axes, leading to infertility and bone loss, and usually is caused by chronic energy deficiency secondary to strenuous exercise and/or decreased food intake. Energy deficiency also leads to hypoleptinemia, which has been proposed, on the basis of observational studies as well as an open-label study, to mediate the neuroendocrine abnormalities associated with this condition. To prove definitively a causal role of leptin in the pathogenesis of HA, we performed a randomized, double-blinded, placebo-controlled trial of human recombinant leptin (metreleptin) in replacement doses over 36 wk in women with HA. We assessed its effects on reproductive outcomes, neuroendocrine function, and bone metabolism. Leptin replacement resulted in recovery of menstruation and corrected the abnormalities in the gonadal, thyroid, growth hormone, and adrenal axes. We also demonstrated changes in markers of bone metabolism suggestive of bone formation, but no changes in bone mineral density were detected over the short duration of this study. If these data are confirmed, metreleptin administration in replacement doses to normalize circulating leptin levels may prove to be a safe and effective therapy for women with HA. PMID:21464293

  14. 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

  15. Functional Interrogation of Adult Hypothalamic Neurogenesis with Focal Radiological Inhibition

    PubMed Central

    Lee, Daniel A.; Salvatierra, Juan; Velarde, Esteban; Wong, John; Ford, Eric C.; Blackshaw, Seth

    2013-01-01

    The functional characterization of adult-born neurons remains a significant challenge. Approaches to inhibit adult neurogenesis via invasive viral delivery or transgenic animals have potential confounds that make interpretation of results from these studies difficult. New radiological tools are emerging, however, that allow one to noninvasively investigate the function of select groups of adult-born neurons through accurate and precise anatomical targeting in small animals. Focal ionizing radiation inhibits the birth and differentiation of new neurons, and allows targeting of specific neural progenitor regions. In order to illuminate the potential functional role that adult hypothalamic neurogenesis plays in the regulation of physiological processes, we developed a noninvasive focal irradiation technique to selectively inhibit the birth of adult-born neurons in the hypothalamic median eminence. We describe a method for Computer tomography-guided focal irradiation (CFIR) delivery to enable precise and accurate anatomical targeting in small animals. CFIR uses three-dimensional volumetric image guidance for localization and targeting of the radiation dose, minimizes radiation exposure to nontargeted brain regions, and allows for conformal dose distribution with sharp beam boundaries. This protocol allows one to ask questions regarding the function of adult-born neurons, but also opens areas to questions in areas of radiobiology, tumor biology, and immunology. These radiological tools will facilitate the translation of discoveries at the bench to the bedside. PMID:24300415

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

    PubMed

    Hu, Yueming; Huang, He; Hui, Xinjie; Cheng, Xi; White, Aaron P; Zhao, Zhendong; Wang, Yejun

    2016-08-01

    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

  17. 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

    2014-09-01

    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

  18. 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

  19. 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

  20. The mechanism of transfer for L-leucine into the vascular bed of the Anuran small intestine.

    PubMed Central

    Cheeseman, C I

    1981-01-01

    1. The vascularly perfused small intestine of Rana pipiens was used to investigate the movement of the amino acid L-leucine from the epithelium into the vascular bed. It was found that only a few amino acids when present in the lumen inhibited the wash-out leucine into the vascular bed. The series of amino acids which had this effect belonged to the group previously shown to be transported by 'L-type' carrier systems. 2. Nearly all amino acids when present in the lumen accelerated the flux of leucine from the vascular bed to the lumen and there was little correlation between the amino acids which caused this effect and those which inhibited leucine wash-out into the vascular bed. Replacement of luminal sodium also promoted serosal-to-mucosal leucine flux. 3. The effect of the presence of amino acids in the lumen on the uptake of leucine from the vascular bed was measured using a fractional extraction technique; sucrose was the extracellular marker. There was complete correlation between the amino acids which promoted the extraction of leucine from the vascular bed and those which inhibited leucine wash-out into the vascular bed. 4. In contrast, the wash-out of leucine into the vascular bed was not accelerated by the addition of amino acids to the vascular perfusate, and the presence of 10 mM-leucine in the vascular bed had very little effect upon the mucosal-to-serosal flux of leucine. 5. These results are discussed with regard to the specificity of an exit system for leucine, in the intestinal epithelium, which appears to have an energy requirement. PMID:6975822

  1. 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. PMID:26745679

  2. 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

  3. Pathophysiology and clinical characteristics of hypothalamic obesity in children and adolescents

    PubMed Central

    Kim, Ja Hye

    2013-01-01

    The hypothalamus plays a key role in the regulation of body weight by balancing the intake of food, energy expenditure, and body fat stores, as evidenced by the fact that most monogenic syndromes of morbid obesity result from mutations in genes expressed in the hypothalamus. Hypothalamic obesity is a result of impairment in the hypothalamic regulatory centers of body weight and energy expenditure, and is caused by structural damage to the hypothalamus, radiotherapy, Prader-Willi syndrome, and mutations in the LEP, LEPR, POMC, MC4R and CART genes. The pathophysiology includes loss of sensitivity to afferent peripheral humoral signals, such as leptin, dysregulated insulin secretion, and impaired activity of the sympathetic nervous system. Dysregulation of 11β-hydroxysteroid dehydrogenase 1 activity and melatonin may also have a role in the development of hypothalamic obesity. Intervention of this complex entity requires simultaneous targeting of several mechanisms that are deranged in patients with hypothalamic obesity. Despite a great deal of theoretical understanding, effective treatment for hypothalamic obesity has not yet been developed. Therefore, understanding the mechanisms that control food intake and energy homeostasis and pathophysiology of hypothalamic obesity can be the cornerstone of the development of new treatments options. Early identification of patients at-risk can relieve the severity of weight gain by the provision of dietary and behavioral modification, and antiobesity medication. This review summarizes recent advances of the pathophysiology, endocrine characteristics, and treatment strategies of hypothalamic obesity. PMID:24904871

  4. Hypothalamic neural circuits regulating maternal responsiveness toward infants.

    PubMed

    Numan, Michael

    2006-12-01

    A theoretical neural model is developed, along with supportive evidence, to explain how the medial preoptic area (MPOA) of the hypothalamus can regulate maternal responsiveness toward infant-related stimuli. It is proposed that efferents from a hormone-primed MPOA (a) depress a central aversion system (composed of neural circuits between the amygdala, medial hypothalamus, and midbrain) so that novel infant stimuli do not activate defensive or avoidance behavior and (b) excite the mesolimbic dopamine system so that active, voluntary maternal responses are promoted. The effects of oxytocin and maternal experience are included in the model, and the specificity of MPOA effects are discussed. The model may be relevant to the mechanisms through which other hypothalamic nuclei regulate other basic motivational states. In addition, aspects of the model may define a core neural circuitry for maternal behavior in mammals. PMID:17099111

  5. 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

  6. NEUROENDOCRINE ACTIONS AND REGULATION OF HYPOTHALAMIC NEUROPEPTIDE Y DURING LACTATION

    PubMed Central

    Crowley, W,R.; Ramoz, G.; Torto, R.; Keefe, K.A.; Wang, J. J.; Kalra, S. P.

    2007-01-01

    The expression of neuropeptide Y (NPY) and its co-messenger, agouti-related peptide (AgRP), in arcuate neurons of the hypothalamus is increased during lactation in rats. Our research has been addressing the questions of the physiological actions of these peptides during lactation and the physiological signals associated with lactation that result in increased expression of their genes. Our studies indicate that NPY and AgRP exert pleiotropic actions during lactation that help integrate neuroendocrine regulation of energy balance with controls over anterior and posterior pituitary hormone secretion. Further, reciprocal signaling to the NPY/AgRP system by leptin and ghrelin is responsible for the changes in expression of these hypothalamic peptides in lactating animals, and thus, may contribute to regulation of food intake and the various neuroendocrine adaptations of lactation. PMID:17241697

  7. Genetic Approaches to Hypothalamic-Pituitary-Adrenal Axis Regulation.

    PubMed

    Arnett, Melinda G; Muglia, Lisa M; Laryea, Gloria; Muglia, Louis J

    2016-01-01

    The normal function of the hypothalamic-pituitary-adrenal (HPA) axis, and resultant glucocorticoid (GC) secretion, is essential for human health. Disruption of GC regulation is associated with pathologic, psychological, and physiological disease states such as depression, post-traumatic stress disorder, hypertension, diabetes, and osteopenia, among others. As such, understanding the mechanisms by which HPA output is tightly regulated in its responses to environmental stressors and circadian cues has been an active area of investigation for decades. Over the last 20 years, however, advances in gene targeting and genome modification in rodent models have allowed the detailed dissection of roles for key molecular mediators and brain regions responsible for this control in vivo to emerge. Here, we summarize work done to elucidate the function of critical neuropeptide systems, GC-signaling targets, and inflammation-associated pathways in HPA axis regulation and behavior, and highlight areas for future investigation. PMID:26189452

  8. 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

    2015-01-01

    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. PMID:25748136

  9. Lateral hypothalamic lesions cause gastric injury by stimulating gastric contractility.

    PubMed

    Garrick, T; Grijalva, C V; Trauner, M

    1993-07-01

    Changes in gastric contractility following lateral hypothalamic (LH) lesions with and without bilateral cervical vagotomy were measured in urethan-anesthetized rats. LH lesions were induced with direct current passed through stereotaxically placed electrodes. Gastric contractility was recorded continuously for 4 h with acutely implanted strain gauge force transducers and analyzed by computer. LH lesions consistently stimulated gastric contractility and caused more gastric mucosal injury than control conditions. Vagotomy blocked both gastric mucosal injury and high-amplitude gastric contractions. In rats with LH lesions and exogenously infused intragastric hydrochloric acid, atropine methyl nitrate inhibited high-amplitude gastric contractions and gastric erosions. These findings indicate that LH lesions stimulate vagally mediated high-amplitude gastric contractions, which, in the presence of hydrochloric acid, cause gastric mucosal erosions. PMID:8338162

  10. Organotypic slice culture of the hypothalamic paraventricular nucleus of rat

    PubMed Central

    Cho, Eun Seong; Lee, So Yeong; Park, Jae-Yong; Hong, Seong-Geun

    2007-01-01

    Organotypic slice cultures have been developed as an alternative to acute brain slices because the neuronal viability and synaptic connectivity in these cultures can be preserved well for a prolonged period of time. This study evaluated a stationary organotypic slice culture developed for the hypothalamic paraventricular nucleus (PVN) of rat. The results showed that the slice cultures maintain the typical shape of the nucleus, the immunocytochemical signals for oxytocin, vasopressin, and corticotropin-releasing hormone, and the electrophysiological properties of PVN neurons for up to 3 weeks in vitro. The PVN neurons in the culture expressed the green fluorescent protein gene that had been delivered by the adenoviral vectors. The results indicate that the cultured slices preserve the properties of the PVN neurons, and can be used in longterm studies on these neurons in vitro. PMID:17322769

  11. 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

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

    PubMed

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

    2015-09-01

    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-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. PMID:25957086

  13. Leucine Loading Test is Only Discriminative for 3-Methylglutaconic Aciduria Due to AUH Defect.

    PubMed

    Wortmann, Saskia B; Kluijtmans, Leo A J; Sequeira, Silvia; Wevers, Ron A; Morava, Eva

    2014-01-01

    Currently, six inborn errors of metabolism with 3-methylglutaconic aciduria as discriminative feature are known. The "Primary 3-methylglutaconic aciduria," 3-methylglutaconyl-CoA hydratase deficiency or AUH defect, is a disorder of leucine catabolism. For all other subtypes, also denoted "Secondary 3-methylglutaconic acidurias" (TAZ defect or Barth syndrome, SERAC1 defect or MEGDEL syndrome, OPA3 defect or Costeff syndrome, DNAJC19 defect or DCMA syndrome, TMEM70 defect, "not otherwise specified (NOS) 3-MGA-uria"), the origin of 3-methylglutaconic aciduria remains enigmatic but is hypothesized to be independent from leucine catabolism. Here we show the results of leucine loading test in 21 patients with different inborn errors of metabolism who present with 3-methylglutaconic aciduria. After leucine loading urinary 3-methylglutaconic acid levels increased only in the patients with an AUH defect. This strongly supports the hypothesis that 3-methylglutaconic aciduria is independent from leucine breakdown in other inborn errors of metabolism with 3-methylglutaconic aciduria and also provides a simple test to discriminate between primary and secondary 3-methylglutaconic aciduria in regular patient care. PMID:24757000

  14. Reduction in plasma leucine after sprint exercise is greater in males than in females.

    PubMed

    Esbjörnsson, M; Rooyackers, O; Norman, B; Rundqvist, H C; Nowak, J; Bülow, J; Simonsen, L; Jansson, E

    2012-06-01

    There is a pronounced gender difference in the accumulation of plasma ammonia after sprint exercise. Ammonia is a key intermediate in amino acid metabolism, which implies that gender-related differences in plasma and muscle amino acid concentrations after sprint exercise exist. To study this, three bouts of 30-s sprint exercise were performed by healthy females (n=8) and males (n=6). Blood leucine and muscle leucine were collected over the exercise period. Basal arterial plasma and skeletal muscle leucine were 40% higher in males than females (P<0.010 and P<0.020). Plasma, but not muscle, leucine decreased by sprint exercise and more so in males than females (g × t: P=0.025). Increase in ammonia was higher in males than females in both plasma and muscle (g × t: P<0.001 and P=0.003). An opposite pattern was shown for plasma glutamine, where an increase was found in females (P<0.001), but not in males. In conclusion, the lower plasma ammonia after sprint exercise in females seems to be explained by a lower accumulation of ammonia in skeletal muscle and by a buffering of ammonia in the form of glutamine in females. The greater reduction in plasma leucine in males seems to be related to their greater increase in muscle ammonia after sprint exercise. PMID:22612362

  15. Incorporation and release of tritiated leucine in rat prostate during castration induced involution

    SciTech Connect

    Bockrath, J.M.; Lee, C.; Grayhack, J.T.

    1981-11-01

    Rates of 3H-leucine incorporation into and release from the ventral prostate during castration induced involution were studied in adult male rats. We measured the rate of 3H-leucine incorporation by incubating the prostatic tissue in medium 199 containing 3H-leucine at 37 C for 1 hour. The rate of radioactivity incorporated into the protein fraction was expressed as cpm mg of protein. This rate reduced linearly from Day 0 to Day 6 post castration. Subcutaneous implantation of a silastic capsule containing crystalline testosterone to castrated rats restored the rate of incorporation to that of sham operated rats. To study the rate of 3H-leucine release, 3H-leucine prepared in 0.9 per cent Na C1 solution was injected intravenously into rats 1 day before castration. The amount of radioactivity remaining in the protein fraction of the prostate, expressed as cpm per prostate, was measured at different intervals after castration or after sham operation. Radioactivity disappeared at a significantly faster rate in the prostate of castrated rats than in sham operated controls. Testosterone replacement to castrated rats delayed the rate of loss of radioactivity to a degree similar to that of sham operated rats. These findings indicate that the rapid rate of protein loss in the regressing prostate is the result of a combined action of an accelerated rate of protein degradation and a rate of protein synthesis. Testosterone administration reversed these patterns of protein metabolism.

  16. 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

  17. Amperometric bienzyme screen-printed biosensor for the determination of leucine.

    PubMed

    Labroo, Pratima; Cui, Yue

    2014-01-01

    Leucine plays an important role in protein synthesis, brain functions, building muscle mass, and helping the body when it undergoes stress. Here, we report a new amperometric bienzyme screen-printed biosensor for the determination of leucine, by coimmobilizing p-hydroxybenzoate hydroxylase (HBH) and leucine dehydrogenase (LDH) on a screen-printed electrode with NADP(+) and p-hydroxybenzoate as the cofactors. The detection principle of the sensor is that LDH catalyzes the specific dehydrogenation of leucine by using NADP(+) as a cofactor. The product, NADPH, triggers the hydroxylation of p-hydroxybenzoate by HBH in the presence of oxygen to produce 3,4-dihydroxybenzoate, which results in a change in electron concentration at the working carbon electrode, which is detected by the potentiostat. The sensor shows a linear detection range between 10 and 600 μM with a detection limit of 2 μM. The response is reproducible and has a fast measuring time of 5-10 s after the addition of a given concentration of leucine. PMID:24220759

  18. Role of the hypothalamic arcuate nucleus in cardiovascular regulation

    PubMed Central

    Sapru, Hreday N.

    2012-01-01

    Recently the hypothalamic arcuate nucleus (Arc) has been implicated in cardiovascular regulation. Both pressor and depressor responses can be elicited by the chemical stimulation of the Arc. The direction of cardiovascular responses (increase or decrease) elicited from the Arc depends on the baseline blood pressure. The pressor responses are mediated via increase in sympathetic nerve activity and involve activation of the spinal ionotropic glutamate receptors. Arc-stimulation elicits tachycardic responses which are mediated via inhibition of vagal input and excitation of sympathetic input to the heart. The pathways within the brain mediating the pressor and tachycardic responses elicited from the Arc have not been delineated. The depressor responses to the Arc-stimulation are mediated via the hypothalamic paraventricular nucleus (PVN). Gamma aminobutyric acid type A receptors, neuropeptide Y1 receptors, and opiate receptors in the PVN mediate the depressor responses elicited from the Arc. Some circulating hormones (e.g., leptin and insulin) may reach the Arc via the leaky blood-brain barrier and elicit their cardiovascular effects. Although the Arc is involved in mediating the cardiovascular responses to intravenously injected angiotensin II and angiotensin-(1-12), these effects may not be due to leakage of these peptides across the blood-brain barrier in the Arc; instead, circulating angiotensins may act on neurons in the SFO and mediate cardiovascular actions via the projections of SFO neurons to the Arc. Cardiovascular responses elicited by acupuncture have been reported to be mediated by direct and indirect projections of the Arc to the RVLM. PMID:23260431

  19. 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

  20. 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. PMID:26587652

  1. 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

  2. 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. PMID:24607345

  3. Thiamine Deficiency Induces Anorexia by Inhibiting Hypothalamic AMPK

    PubMed Central

    Liu, Mei; Alimov, Alexander; Wang, Haiping; Frank, Jacqueline A.; Katz, Wendy; Xu, Mei; Ke, Zun-Ji; Luo, Jia

    2014-01-01

    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 16 days, 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 9 folds 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 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. PMID:24607345

  4. Activation of the retrotrapezoid nucleus by posterior hypothalamic stimulation

    PubMed Central

    Fortuna, Michal G; Stornetta, Ruth L; West, Gavin H; Guyenet, Patrice G

    2009-01-01

    The retrotrapezoid nucleus (RTN) contains chemically defined neurons (ccRTN neurons) that provide a pH-regulated excitatory drive to the central respiratory pattern generator. Here we test whether ccRTN neurons respond to stimulation of the perifornical hypothalamus (PeF), a region that regulates breathing during sleep, stress and exercise. PeF stimulation with gabazine increased blood pressure, phrenic nerve discharge (PND) and the firing rate of ccRTN neurons in isoflurane-anaesthetized rats. Gabazine produced an approximately parallel upward shift of the steady-state relationship between ccRTN neuron firing rate and end-tidal CO2, and a similar shift of the relationship between PND and end-tidal CO2. The central respiratory modulation of ccRTN neurons persisted after gabazine without a change in pattern. Morphine administration typically abolished PND and reduced the discharge rate of most ccRTN neurons (by 25% on average). After morphine administration, PeF stimulation activated the ccRTN neurons normally but PND activation and the central respiratory modulation of the ccRTN neurons were severely attenuated. In the same rat preparation, most (58%) ccRTN neurons expressed c-Fos after exposure to hypercapnic hyperoxia (6–7% end-tidal CO2; 3.5 h; no hypothalamic stimulation) and 62% expressed c-Fos under hypocapnia (∼3% end-tidal CO2) after PeF stimulation. Under baseline conditions (∼3% end-tidal CO2, hyperoxia, no PeF stimulation) few (11%) ccRTN neurons expressed c-Fos. In summary, most ccRTN neurons are excited by posterior hypothalamic stimulation while retaining their normal response to CNS acidification. ccRTN neurons probably contribute both to the chemical drive of breathing and to the feed-forward control of breathing associated with emotions and or locomotion. PMID:19752119

  5. Role of the hypothalamic arcuate nucleus in cardiovascular regulation.

    PubMed

    Sapru, Hreday N

    2013-04-01

    Recently the hypothalamic arcuate nucleus (Arc) has been implicated in cardiovascular regulation. Both pressor and depressor responses can be elicited by the chemical stimulation of the Arc. The direction of cardiovascular responses (increase or decrease) elicited from the Arc depends on the baseline blood pressure. The pressor responses are mediated via increase in sympathetic nerve activity and involve activation of the spinal ionotropic glutamate receptors. Arc-stimulation elicits tachycardic responses which are mediated via inhibition of vagal input and excitation of sympathetic input to the heart. The pathways within the brain mediating the pressor and tachycardic responses elicited from the Arc have not been delineated. The depressor responses to the Arc-stimulation are mediated via the hypothalamic paraventricular nucleus (PVN). Gamma aminobutyric acid type A receptors, neuropeptide Y1 receptors, and opiate receptors in the PVN mediate the depressor responses elicited from the Arc. Some circulating hormones (e.g., leptin and insulin) may reach the Arc via the leaky blood-brain barrier and elicit their cardiovascular effects. Although the Arc is involved in mediating the cardiovascular responses to intravenously injected angiotensin II and angiotensin-(1-12), these effects may not be due to leakage of these peptides across the blood-brain barrier in the Arc; instead, circulating angiotensins may act on neurons in the SFO and mediate cardiovascular actions via the projections of SFO neurons to the Arc. Cardiovascular responses elicited by acupuncture have been reported to be mediated by direct and indirect projections of the Arc to the RVLM. PMID:23260431

  6. A Role for the Kp Leucine Zipper in Regulating P Element Transposition in Drosophila Melanogaster

    PubMed Central

    Andrews, J. D.; Gloor, G. B.

    1995-01-01

    The KP element can repress P element mobility in Drosophila melanogaster. Three mutant KP elements were made that had either two amino acid substitutions or a single amino acid deletion in the putative leucine zipper domain found in the KP polypeptide. Each KP element was expressed from the actin 5C proximal promoter. The wild-type control construct strongly repressed P element mobility, measured by the GD sterility and sn(w) mutability assays, in a position-independent manner. The single amino acid deletion mutant failed to repress P mobility regardless of its insertion site, while repression of P element mobility by the double amino acid substitution mutants was position dependent. The results show that the leucine zipper of the KP polypeptide is important for P element regulation. This supports the multimer-poisoning model of P element repression, because leucine zipper motifs are involved in protein-protein interactions. PMID:8647395

  7. 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.

  8. 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.

  9. Stimulation of the hypothalamic arcuate nucleus increases brown adipose tissue nerve activity via hypothalamic paraventricular and dorsomedial nuclei.

    PubMed

    Chitravanshi, Vineet C; Kawabe, Kazumi; Sapru, Hreday N

    2016-08-01

    Hypothalamic arcuate nucleus (ARCN) stimulation elicited increases in sympathetic nerve activity (IBATSNA) and temperature (TBAT) of interscapular brown adipose tissue (IBAT). The role of hypothalamic dorsomedial (DMN) and paraventricular (PVN) nuclei in mediating these responses was studied in urethane-anesthetized, artificially ventilated, male Wistar rats. In different groups of rats, inhibition of neurons in the DMN and PVN by microinjections of muscimol attenuated the increases in IBATSNA and TBAT elicited by microinjections of N-methyl-d-aspartic acid into the ipsilateral ARCN. In other groups of rats, blockade of ionotropic glutamate receptors by combined microinjections of D(-)-2-amino-7-phosphono-heptanoic acid (D-AP7) and NBQX into the DMN and PVN attenuated increases in IBATSNA and TBAT elicited by ARCN stimulation. Blockade of melanocortin 3/4 receptors in the DMN and PVN in other groups of rats resulted in attenuation of increases in IBATSNA and TBAT elicited by ipsilateral ARCN stimulation. Microinjections of Fluoro-Gold into the DMN resulted in retrograde labeling of cells in the ipsilateral ARCN, and some of these cells contained proopiomelanocortin (POMC), α-melanocyte-stimulating hormone (α-MSH), or vesicular glutamate transporter-3. Since similar projections from ARCN to the PVN have been reported by us and others, these results indicate that neurons containing POMC, α-MSH, and glutamate project from the ARCN to the DMN and PVN. Stimulation of ARCN results in the release of α-MSH and glutamate in the DMN and PVN which, in turn, cause increases in IBATSNA and TBAT. PMID:27402666

  10. Leucine metabolism in TNF-alpha- and endotoxin-treated rats: contribution of hepatic tissue.

    PubMed

    Holecek, M; Sprongl, L; Skopec, F; Andrýs, C; Pecka, M

    1997-12-01

    The effects of tumor necrosis factor-alpha (TNF-alpha; cachectin) and lipopolysaccharide of Salmonella enteritidis (LPS; endotoxin) on leucine metabolism in rats were evaluated in the whole body using intravenous infusion of L-[1-14C]leucine and in isolated perfused liver (IPL) using the single-pass perfusion technique with alpha-keto[1-14C]isocaproate as a tracer for measurement of ketoisocaproic acid (KIC) oxidation, and the recirculation technique for measurement of hepatic amino acid exchanges. The data obtained in TNF-alpha and LPS groups were compared with those obtained in controls. Both TNF-alpha and LPS treatment induced an increase of whole body leucine turnover, oxidation, and clearance. As the result of a higher increase of leucine oxidation than of incorporation into the pool of body proteins, the fractional oxidation of leucine was increased. The fractional rate of protein synthesis increased significantly in the spleen (both in TNF-alpha and LPS rats), in blood plasma, liver, colon, kidneys, gastrocnemius muscle (in LPS rats), and in lungs (TNF-alpha-treated rats), whereas it decreased in the jejunum (LPS rats). In IPL of TNF-alpha- and LPS-treated rats a decrease of KIC oxidation and higher uptake of branched-chain amino acids (BCAA; valine, leucine, and isoleucine) were observed when compared with control animals. We hypothesize that the negative consequences of increased whole body proteolysis and of increased oxidation of BCAA induced by TNF-alpha and/or LPS are reduced by decreased activity of hepatic branched-chain ketoacid dehydrogenase that can help resupply BCAA to the body. PMID:9435518

  11. Plasma arginine and leucine kinetics and urea production rates in burn patients.

    PubMed

    Yu, Y M; Young, V R; Castillo, L; Chapman, T E; Tompkins, R G; Ryan, C M; Burke, J F

    1995-05-01

    We measured plasma arginine and leucine kinetics and rates of urea production (appearance) in 12 severely burned patients (mean body surface burn area, 48%) during a basal state (low-dose intravenous glucose) and while receiving routine, total parenteral nutrition ([TPN] fed state) including an L-amino acid mixture, supplying a generous level of nitrogen (mean, 0.36 g N.kg-1.d-1). The two nutritional states were studied in random order using a primed 4-hour constant intravenous tracer infusion protocol. Stable-nuclide-labeled tracers were L-[guanidino-13C]arginine, L-[1-13C]leucine, [18O]urea, and NaH13CO3 (prime only), with blood and expired air samples drawn at intervals to determine isotopic abundance of arginine, citrulline, ornithine, alpha-ketoisocaproate ([KIC] for leucine), and urea in plasma and 13CO2 in breath. Results are compared with data obtained in these laboratories in healthy adults. Leucine kinetics (flux and disappearance into protein synthesis) indicated the expected higher turnover in burn patients than in healthy controls. Mean leucine oxidation rates are also higher and compared well with values predicted from urea production rates, provided that urea nitrogen recycling via intestinal hydrolysis is taken into account. The plasma urea flux was also higher than for normal subjects. Arginine fluxes as measured in the systemic whole body, via the plasma pool, were correspondingly higher in burned patients than in healthy controls and were in good agreement with values predicted from leucine-KIC kinetics. However, systemic whole-body arginine flux measured via the plasma pool was only 20% of the arginine flux estimated from the urea flux plus the rate of protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7752916

  12. Transport of leucine, isoleucine and valine by luminal membrane vesicles from rabbit proximal tubule.

    PubMed

    Jørgensen, K E; Kragh-Hansen, U; Sheikh, M I

    1990-03-01

    1. Transport of L- and D-isomers of leucine, isoleucine and valine by luminal membrane vesicles prepared from either the convoluted part (pars convoluta) or the straight part (pars recta) of rabbit proximal tubule was studied by a rapid filtration technique and by a spectrophotometric method using a potential-sensitive carbocyanine dye. 2. Both types of renal membrane vesicle take up the amino acids in a Na(+)-dependent, H(+)-independent and electrogenic manner. The L-isomers are transported with higher affinities than their corresponding D-forms, of which only D-leucine is taken up to a significant extent. 3. Membrane vesicles prepared from pars convoluta take up the L-amino acids by a single and common system. Filtration studies showed that the Km values for L-leucine and L-valine transport are, on average, 0.23 and 0.83 mM, respectively. The values of KA (the concentration of amino acid producing a half-maximal optical response) are comparable to those of Km, namely 0.18 mM for L-leucine and 0.60 mM for L-valine. KA for L-isoleucine transport was found to be 0.19 mM. D-Leucine is taken up by the same system but with a much lower affinity (KA = 7.2 mM). 4. Membrane vesicles prepared from pars recta possess two, and probably common, transport systems for the L-isomers of the amino acids. The average Michaelis-Menten constants were as follows: L-leucine, K1m = 0.17 mM, K2m = 6.5 mM; L-valine, K1m = 0.19 mM, K2m = 11.5 mM. The KA values were: L-leucine, K1A = 0.12 mM, K2A = 7.4 mM; L-valine, K1A = 0.18 mM, K2A = 10.0 mM; L-isoleucine, K1A = 0.17 mM, K2A = 9.0 mM. D-Leucine is taken up by a low-affinity system only (KA = 6.5 mM), which seems to be the same as the low-affinity system transporting the L-forms of the amino acids. PMID:2352186

  13. Leptin signaling in GFAP-expressing adult glia cells regulates hypothalamic neuronal circuits and feeding

    PubMed Central

    Kim1, Jae Geun; Suyama, Shigetomo; Koch, Marco; Jin, Sungho; Argente-Arizon, Pilar; Argente, Jesus; 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.

    2014-01-01

    We have shown that synaptic re-organization of hypothalamic feeding circuits in response to metabolic shifts involves astrocytes, cells that can directly respond to the metabolic hormone, leptin, in vitro. It is not known whether the role of glia cells in hypothalamic synaptic adaptions is active or passive. Here we show that leptin receptors are expressed in hypothalamic astrocytes and that conditional, adult deletion of leptin receptors in astrocytes leads to altered glial morphology, decreased glial coverage and elevated synaptic inputs onto pro-opiomelanocortin (POMC)- and Agouti-related protein (AgRP)-producing neurons. Leptin-induced suppression of feeding was diminished, while rebound feeding after fasting or ghrelin administration was elevated in mice with astrocyte-specific leptin receptor deficiency. These data unmask an active role of glial cells in the initiation of hypothalamic synaptic plasticity and neuroendocrine control of feeding by leptin. PMID:24880214

  14. Precocious puberty in rats induced by hypothalamic lesions: a comparison of platinum and stainless steel electrodes.

    PubMed

    Ruf, K B; YoungLai, E V; Kitchen, J H; Vuillet, M

    1976-05-15

    Precocious sexual maturation was induced in immature female rats by 2 types of unilateral hypothalamic lesions. Stainless steel electrodes produced smaller tissue defects but proved more efficient than platinum electrodes. PMID:1278327

  15. Growth, Hypothalamic Function, and Brain Ventricle Size in Mentally Retarded Subjects

    ERIC Educational Resources Information Center

    Leisti, S.; Iianainen, M.

    1978-01-01

    To determine whether moderate enlargement of the third brain ventricle or the temporal horns of the lateral ventricles was associated with hypothalamic dysfunction, 15 mentally retarded Ss (ages 12-25 years) with such characteristics were studies. (DLS)

  16. Specification of select hypothalamic circuits and innate behaviors by the embryonic patterning gene Dbx1

    PubMed Central

    Sokolowski, Katie; Esumi, Shigeyuki; Hirata, Tsutomu; Kamal, Yasman; Tran, Tuyen; Lam, Andrew; Oboti, Livio; Brighthaupt, Sherri-Chanelle; Zaghlula, Manar; Martinez, Jennifer; Ghimbovschi, Svetlana; Knoblach, Susan; Pierani, Alessandra; Tamamaki, Nobuaki; Shah, Nirao M; Jones, Kevin S; Corbin, Joshua G

    2015-01-01

    SUMMARY The hypothalamus integrates information required for the production of a variety of innate behaviors such as feeding, mating, aggression and predator avoidance. Despite an extensive knowledge of hypothalamic function, how embryonic genetic programs specify circuits that regulate these behaviors remains unknown. Here, we find that in the hypothalamus the developmentally regulated homeodomain-containing transcription factor Dbx1 is required for the generation of specific subclasses of neurons within the lateral hypothalamic area/zona incerta (LH) and the arcuate (Arc) nucleus. Consistent with this specific developmental role, Dbx1 hypothalamic-specific conditional-knockout mice display attenuated responses to predator odor and feeding stressors but do not display deficits in other innate behaviors such as mating or conspecific aggression. Thus, activity of a single developmentally regulated gene, Dbx1, is a shared requirement for the specification of hypothalamic nuclei governing a subset of innate behaviors. PMID:25864637

  17. Glucose Enhances Basal or Melanocortin-Induced cAMP-Response Element Activity in Hypothalamic Cells.

    PubMed

    Breit, Andreas; Wicht, Kristina; Boekhoff, Ingrid; Glas, Evi; Lauffer, Lisa; Mückter, Harald; Gudermann, Thomas

    2016-07-01

    Melanocyte-stimulating hormone (MSH)-induced activation of the cAMP-response element (CRE) via the CRE-binding protein in hypothalamic cells promotes expression of TRH and thereby restricts food intake and increases energy expenditure. Glucose also induces central anorexigenic effects by acting on hypothalamic neurons, but the underlying mechanisms are not completely understood. It has been proposed that glucose activates the CRE-binding protein-regulated transcriptional coactivator 2 (CRTC-2) in hypothalamic neurons by inhibition of AMP-activated protein kinases (AMPKs), but whether glucose directly affects hypothalamic CRE activity has not yet been shown. Hence, we dissected effects of glucose on basal and MSH-induced CRE activation in terms of kinetics, affinity, and desensitization in murine, hypothalamic mHypoA-2/10-CRE cells that stably express a CRE-dependent reporter gene construct. Physiologically relevant increases in extracellular glucose enhanced basal or MSH-induced CRE-dependent gene transcription, whereas prolonged elevated glucose concentrations reduced the sensitivity of mHypoA-2/10-CRE cells towards glucose. Glucose also induced CRCT-2 translocation into the nucleus and the AMPK activator metformin decreased basal and glucose-induced CRE activity, suggesting a role for AMPK/CRTC-2 in glucose-induced CRE activation. Accordingly, small interfering RNA-induced down-regulation of CRTC-2 expression decreased glucose-induced CRE-dependent reporter activation. Of note, glucose also induced expression of TRH, suggesting that glucose might affect the hypothalamic-pituitary-thyroid axis via the regulation of hypothalamic CRE activity. These findings significantly advance our knowledge about the impact of glucose on hypothalamic signaling and suggest that TRH release might account for the central anorexigenic effects of glucose and could represent a new molecular link between hyperglycaemia and thyroid dysfunction. PMID:27144291

  18. 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

  19. Leucine stimulates protein synthesis in skeletal muscle of neonatal pigs by enhancing mTORC1 activation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Skeletal muscle in the neonate grows at a rapid rate due in part to an enhanced sensitivity to the postprandial rise in amino acids, particularly leucine. To elucidate the molecular mechanism by which leucine stimulates protein synthesis in neonatal muscle, overnight-fasted 7-day-old piglets were tr...

  20. Involvement of protein kinase C activation in L-leucine-induced stimulation of protein synthesis in l6 myotubes.

    PubMed

    Yagasaki, Kazumi; Morisaki, Naoko; Kitahara, Yoshiro; Miura, Atsuhito; Funabiki, Ryuhei

    2003-11-01

    Effects of leucine and related compounds on protein synthesis were studied in L6 myotubes. The incorporation of [(3)H]tyrosine into cellular protein was measured as an index of protein synthesis. In leucine-depleted L6 myotubes, leucine and its keto acid, alpha-ketoisocaproic acid (KIC), stimulated protein synthesis, while D-leucine did not. Mepacrine, an inhibitor of both phospholipases A(2) and C, canceled stimulatory actions of L-leucine and KIC on protein synthesis. Neither indomethacin, an inhibitor of cyclooxygenase, nor caffeic acid, an inhibitor of lipoxygenase, diminished their stimulatory actions, suggesting no involvement of arachidonic acid metabolism. Conversely, 1-O-hexadecyl-2-O-methylglycerol, an inhibitor of proteinkinase C, significantly canceled the stimulatory actions of L-leucine and KIC on protein synthesis, suggesting an involvement of phosphatidylinositol degradation and activation of protein kinase C. L-Leucine caused a rapid activation of protein kinase C in both cytosol and membrane fractions of the cells. These results strongly suggest that both L-leucine and KIC stimulate protein synthesis in L6 myotubes through activation of phospholipase C and protein kinase C. PMID:19003213

  1. Activation of Strychnine-Sensitive Glycine Receptors by Shilajit on Preoptic Hypothalamic Neurons of Juvenile Mice.

    PubMed

    Bhattarai, Janardhan Prasad; Cho, Dong Hyu; Han, Seong Kyu

    2016-02-29

    Shilajit, a mineral pitch, has been used in Ayurveda and Siddha system of medicine to treat many human ailments, and is reported to contain at least 85 minerals in ionic form. This study examined the possible mechanism of Shilajit action on preoptic hypothalamic neurons using juvenile mice. The hypothalamic neurons are the key regulator of many hormonal systems. In voltage clamp mode at a holding potential of -60 mV, and under a high chloride pipette solution, Shilajit induced dose-dependent inward current. Shilajit-induced inward currents were reproducible and persisted in the presence of 0.5 μM tetrodotoxin (TTX) suggesting a postsynaptic action of Shilajit on hypothalamic neurons. The currents induced by Shilajit were almost completely blocked by 2 μM strychnine (Stry), a glycine receptor antagonist. In addition, Shilajit-induced inward currents were partially blocked by bicuculline. Under a gramicidin-perforated patch clamp mode, Shilajit induced membrane depolarization on juvenile neurons. These results show that Shilajit affects hypothalamic neuronal activities by activating the Stry-sensitive glycine receptor with α₂/α₂β subunit. Taken together, these results suggest that Shilajit contains some ingredients with possible glycine mimetic activities and might influence hypothalamic neurophysiology through activation of Stry-sensitive glycine receptor-mediated responses on hypothalamic neurons postsynaptically. PMID:26875561

  2. Increasing Fatty Acid Oxidation Remodels the Hypothalamic Neurometabolome to Mitigate Stress and Inflammation

    PubMed Central

    McFadden, Joseph W.; Aja, Susan; Li, Qun; Bandaru, Veera V. R.; Kim, Eun-Kyoung; Haughey, Norman J.; Kuhajda, Francis P.; Ronnett, Gabriele V.

    2014-01-01

    Modification of hypothalamic fatty acid (FA) metabolism can improve energy homeostasis and prevent hyperphagia and excessive weight gain in diet-induced obesity (DIO) from a diet high in saturated fatty acids. We have shown previously that C75, a stimulator of carnitine palmitoyl transferase-1 (CPT-1) and fatty acid oxidation (FAOx), exerts at least some of its hypophagic effects via neuronal mechanisms in the hypothalamus. In the present work, we characterized the effects of C75 and another anorexigenic compound, the glycerol-3-phosphate acyltransferase (GPAT) inhibitor FSG67, on FA metabolism, metabolomics profiles, and metabolic stress responses in cultured hypothalamic neurons and hypothalamic neuronal cell lines during lipid excess with palmitate. Both compounds enhanced palmitate oxidation, increased ATP, and inactivated AMP-activated protein kinase (AMPK) in hypothalamic neurons in vitro. Lipidomics and untargeted metabolomics revealed that enhanced catabolism of FA decreased palmitate availability and prevented the production of fatty acylglycerols, ceramides, and cholesterol esters, lipids that are associated with lipotoxicity-provoked metabolic stress. This improved metabolic signature was accompanied by increased levels of reactive oxygen species (ROS), and yet favorable changes in oxidative stress, overt ER stress, and inflammation. We propose that enhancing FAOx in hypothalamic neurons exposed to excess lipids promotes metabolic remodeling that reduces local inflammatory and cell stress responses. This shift would restore mitochondrial function such that increased FAOx can produce hypothalamic neuronal ATP and lead to decreased food intake and body weight to improve systemic metabolism. PMID:25541737

  3. Role of Hypothalamic VGF in Energy Balance and Metabolic Adaption to Environmental Enrichment in Mice.

    PubMed

    Foglesong, Grant D; Huang, Wei; Liu, Xianglan; Slater, Andrew M; Siu, Jason; Yildiz, Vedat; Salton, Stephen R J; Cao, Lei

    2016-03-01

    Environmental enrichment (EE), a housing condition providing complex physical, social, and cognitive stimulation, leads to improved metabolic health and resistance to diet-induced obesity and cancer. One underlying mechanism is the activation of the hypothalamic-sympathoneural-adipocyte axis with hypothalamic brain-derived neurotrophic factor (BDNF) as the key mediator. VGF, a peptide precursor particularly abundant in the hypothalamus, was up-regulated by EE. Overexpressing BDNF or acute injection of BDNF protein to the hypothalamus up-regulated VGF, whereas suppressing BDNF signaling down-regulated VGF expression. Moreover, hypothalamic VGF expression was regulated by leptin, melanocortin receptor agonist, and food deprivation mostly paralleled to BDNF expression. Recombinant adeno-associated virus-mediated gene transfer of Cre recombinase to floxed VGF mice specifically decreased VGF expression in the hypothalamus. In contrast to the lean and hypermetabolic phenotype of homozygous germline VGF knockout mice, specific knockdown of hypothalamic VGF in male adult mice led to increased adiposity, decreased core body temperature, reduced energy expenditure, and impaired glucose tolerance, as well as disturbance of molecular features of brown and white adipose tissues without effects on food intake. However, VGF knockdown failed to block the EE-induced BDNF up-regulation or decrease of adiposity indicating a minor role of VGF in the hypothalamic-sympathoneural-adipocyte axis. Taken together, our results suggest hypothalamic VGF responds to environmental demands and plays an important role in energy balance and glycemic control likely acting in the melanocortin pathway downstream of BDNF. PMID:26730934

  4. The Recreational Drug Ecstasy Disrupts the Hypothalamic-Pituitary-Gonadal Reproductive Axis in Adult Male Rats

    PubMed Central

    Dickerson, Sarah M.; Walker, Deena M.; Reveron, Maria E.; Duvauchelle, Christine L.; Gore, Andrea C.

    2009-01-01

    Reproductive function involves an interaction of three regulatory levels: hypothalamus, pituitary, and gonad. The primary drive upon this system comes from hypothalamic gonadotropin-releasing hormone (GnRH) neurosecretory cells, which receive afferent inputs from other neurotransmitter systems in the central nervous system to result in the proper coordination of reproduction and the environment. Here, we hypothesized that the recreational drug ±-3,4-Methylenedioxymethamphetamine (MDMA; “ecstasy”), which acts through several of the neurotransmitter systems that affect GnRH neurons, suppresses the hypothalamic-pituitary-gonadal (HPG) reproductive axis of male rats. Adult male Sprague-Dawley rats self-administered saline or MDMA or saline either once (acute) or for 20 days (chronic), and were euthanized 7 days following last administration. We quantified hypothalamic GnRH mRNA, serum luteinizing hormone (LH) concentrations, and serum testosterone levels, as indices of hypothalamic, pituitary, and gonadal functions, respectively. The results indicate that the hypothalamic and gonadal levels of the HPG axis are significantly altered by MDMA, with GnRH mRNA and serum testosterone levels suppressed in rats administered MDMA compared to saline. Furthermore, our finding that hypothalamic GnRH mRNA levels are suppressed in the context of low testosterone concentrations suggests that the central GnRH neurosecretory system may be a primary target of inhibitory regulation by MDMA usage. PMID:18309234

  5. Hypothalamic thyroid hormone feedback in health and disease.

    PubMed

    Fliers, Eric; Alkemade, Anneke; Wiersinga, Wilmar M; Swaab, Dick F

    2006-01-01

    The role of the human hypothalamus in the neuroendocrine response to illness has only recently begun to be explored. Extensive changes in the hypothalamus-pituitary-thyroid (HPT) axis occur within the framework of critical illness. The best-documented change in the HPT axis is a decrease in serum concentrations of the biologically active thyroid hormone triiodothyronine (T3). From studies in post-mortem human hypothalamus it appeared that low serum T3 and thyrotropin (TSH) during illness (nonthyroidal illness, NTI) are paralleled by decreased thyrotropin-releasing hormone (TRH)mRNA expression in the hypothalamic paraventricular nucleus (PVN), pointing to a major alteration in HPT axis setpoint regulation. A strong decrease in TRHmRNA expression is also present in the PVN of patients with major depression as well as in glucocorticoid-treated patients. By inference, hypercortisolism in hospitalized patients with severe depression or in critical illness may induce down-regulation of the HPT axis at the level of the hypothalamus. In order to start defining the determinants and mechanisms of these setpoint changes in various clinical conditions, it is important to note that an increasing number of hypothalamic proteins appears to be involved in central thyroid hormone metabolism. In recent studies, we have investigated the distribution and expression of thyroid hormone receptor (TR) isoforms, type 2 and type 3 deiodinase (D2 and D3), and the thyroid hormone transporter monocarboxylate transporter 8 (MCT8) in the human hypothalamus by a combination of immunocytochemistry, mRNA in situ hybridization and enzyme activity assays. Both D2 and D3 enzyme activities are detectable in the mediobasal hypothalamus. D2 immunoreactivity is prominent in glial cells of the infundibular nucleus/median eminence region and in tanycytes lining the third ventricle. Combined D2, D3, MCT8 or TR immunocytochemistry and TRHmRNA in situ hybridization indicates that D3, MCT8 and TRs are all

  6. Hypothalamic hamartoma with precocious puberty: a case report.

    PubMed

    Amin, M S; Kader, M A; Huq, F I; Khan, N A

    2012-07-01

    Hypothalamic hamartoma (HH) is one of the most important causes of central precocious puberty in male children. Hamartomas are malformations composed of ectopic gonadotropic hormone (GnRH) neurons which secrete pulsatile gonadotropin releasing hormone. They are generally observed in children under 3 years. A case of 11/3 year-old male child presented with premature development of secondary sexual characters i.e., growth of pubic and axillary hair, enlargement of penis and acne over the face for the last 5 months. On physical examination, his height was 1.02 m and his weight 18kg, enlarged penile length of which 58mm; testicles were enlarged in size right one measuring 32X25mm and the left 30X23mm. His hematological and other biochemical investigations revealed no abnormality. Plain radiographic examination revealed radiological bone age of about 8-9 years. Endocrinological findings were as follows: Follicle stimulating hormone (FSH): 1.5mIU/ml, Luteinizing hormone (LH): 9.1mIU/ml, Testosterone: 701ng/dl (Testosterone level less than 30ng/dl in prepubertal age). Thyroid function tests were normal. Patient showed no adrenal pathology on ultrasound and his testicular parenchyma was homogeneous echotexture with the size of 30X22X16mm on the right (volume 5.4ml) and 30X20X15mm on the left (volume 4.6ml). With above physical & endocrinological findings and age of the child, it was suspected as a case of central precocious puberty. Subsequently MR imaging of the brain done & showed an oval non-enhancing pedunculated hypothalamic mass arising from the tubercinereum that was iso to hypointense to brain parenchyma on T1 - and intermediate signal on T2-weighted images, 20X10X10mm in diameter, extending into suprasellar cistern. During follow up after 06 months of starting conservative medication with gonadotropin-releasing hormone (GnRH) analog (Leuprolide acetate), his progression of puberty has been arrested and the testosterone level 18ng/dl, which is normal for his age

  7. Decarboxylation of [1-(13)C]leucine by hydroxyl radicals.

    PubMed

    Guitton, J; Tinardon, F; Lamrini, R; Lacan, P; Desage, M; Francina, A

    1998-08-01

    The decarboxylation of [1-13C]leucine by hydroxyl radicals was studied by using gas chromatography-isotope ratio mass spectrometry (GC-IRMS) to follow the production of 13CO2. A Fenton reaction between a (Fe2+)-porphyrin and hydrogen peroxide under aerobic conditions yielded hydroxyl radicals. The decarboxylation rates (VLeu) measured by GC-IRMS were dependent on [1-13C]leucine, porphyrin and hydrogen peroxide concentrations. The 13CO2 production was also dependent on bicarbonate or carbon dioxide added in the reaction medium. Bicarbonate facilitated 13CO2 production, whereas carbon dioxide decreased 13CO2 production. Proton effects on some decarboxylation intermediates could explain bicarbonate or carbon dioxide effects. No effect on the decarboxylation rates was observed in the presence of the classical hydroxyl radicals scavengers dimethyl sulfoxide, mannitol, and uric acid. By contrast, a competitive effect with a strong decrease of the decarboxylation rates was observed in the presence of various amino acids: unlabeled leucine, valine, phenylalanine, cysteine, lysine, and histidine. Two reaction products, methyl-4 oxo-2 pentanoate and methyl-3 butanoate were identified by gas chromatography-mass spectrometry in comparison with standards. The present results suggest that [1-13C]leucine can participate to the coordination sphere of (Fe2+)-porphyrin, with a caged process of the hydroxyl radicals which cannot get out of the coordination sphere. PMID:9680180

  8. Leucine: tRNA Ligase from Cultured Cells of Nicotiana tabacum var. Xanthi

    PubMed Central

    Gore, Nigel R.; Wray, John L.

    1978-01-01

    Leucine:tRNA ligase was assayed in extracts from cultured tobacco (Nicotiana tabacum) XD cells by measuring the initial rate of aminoacylation of transfer RNA with l-[4,5-3H]leucine. Transfer RNA was purified from tobacco XD cells after the method of Vanderhoef et al. (Phytochemistry 9: 2291-2304). The buoyant density of leucine:tRNA ligase from cells grown for 100 generations in 2.5 mm [15N]nitrate and 30% deuterium oxide was 1.3397. After transfer of cells into light medium (2.5 mm [14N]nitrate and 100% H2O) the ligase activity increased and the buoyant density decreased with time to 1.3174 at 72 hours after transfer. It was concluded that leucine:tRNA ligase molecules were synthesized de novo from light amino acids during the period of activity increase. The width at half-peak height of the enzyme distribution profiles following isopycnic equilibrium centrifugation in caesium chloride remained constant at all times after transfer into light medium providing evidence for the loss of preexisting functional ligase molecules. It was concluded that during the period of activity increase the cellular level of enzyme activity was determined by a balance between de novo synthesis and the loss of functional enzyme molecules due to either inactivation or degradation. PMID:16660229

  9. 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

  10. '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. PMID:26902097

  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. Two Di-Leucine Motifs Regulate Trafficking of Mucolipin-1 to Lysosomes

    PubMed Central

    Vergarajauregui, Silvia; Puertollano, Rosa

    2006-01-01

    Mutations in the mucolipin-1 gene have been linked to mucolipidosis type IV, a lysosomal storage disorder characterized by severe neurological and ophthalmologic abnormalities. Mucolipin-1 is a membrane protein containing six putative transmembrane domains with both its N- and C-termini localized facing the cytosol. To gain information on the sorting motifs that mediate the trafficking of this protein to lysosomes, we have generated chimeras in which the N- and C- terminal tail portions of mucolipin-1 were fused to a reporter gene. In this article, we report the identification of two separate di-leucine-type motifs that co-operate to regulate the transport of mucolipin-1 to lysosomes. One di-leucine motif is positioned at the N-terminal cytosolic tail and mediates direct transport to lysosomes, whereas the other di-leucine motif is found at the C-terminal tail and functions as an adaptor protein 2-dependent internalization motif. We have also found that the C-terminal tail of mucolipin-1 is palmitoylated and that this modification might regulate the efficiency of endocytosis. Finally, the mutagenesis of both di-leucine motifs abrogated lysosomal accumulation and resulted in cell-surface redistribution of mucolipin-1. Taken together, these results reveal novel information regarding the motifs that regulate mucolipin-1 trafficking and suggest a role for palmitoylation in protein sorting. PMID:16497227

  13. Prolonged leucine infusion differentially affects tissue protein synthesis in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  14. Role of glucocorticoid-induced leucine zipper (GILZ) in bone acquisition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  15. Identification and mapping of nucleotide binding site-leucine rich repeat resistance gene analogs in bermudagrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thirty-one bermudagrass (Cynodon spp.) disease resistance gene homologs (BRGH) were cloned and sequenced from diploid, triploid, and hexaploid bermudagrass using degenerate primers to target the nucleotide binding site (NBS) of the NBS- leucine rich repeat (LRR) resistance gene family. Alignment of ...

  16. Impact of prolonged leucine supplementation on protein synthesis and lean growth in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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. ...

  17. Selective single crystal complexation of L- or D-leucine by p-sulfonatocalix[6]arene.

    PubMed

    Atwood, Jerry L; Dalgarno, Scott J; Hardie, Michaele J; Raston, Colin L

    2005-01-21

    p-Sulfonatocalix[6]arene, organised in the 'double cone' conformation, has multi-guest capability binding either L- or D-leucine in a single crystal in a bi-layer type arrangement from a racemic mixture of the amino acid. PMID:15645029

  18. Leucine pulses enhance skeletal muscle protein synthesis during continuous feeding in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 stimulation of muscle protein synthesis by leucine in neonates is dependent on amino acid availability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rise in amino acids and insulin after a meal independently stimulate protein synthesis in skeletal muscle of neonates by activating the intracellular signalling pathways that regulate mRNA translation. Leucine, in particular, is important in mediating the response to amino acids. Previously, w...

  20. Retino-hypothalamic regulation of light-induced murine sleep

    PubMed Central

    Muindi, Fanuel; Zeitzer, Jamie M.; Heller, Horace Craig

    2014-01-01

    The temporal organization of sleep is regulated by an interaction between the circadian clock and homeostatic processes. Light indirectly modulates sleep through its ability to phase shift and entrain the circadian clock. Light can also exert a direct, circadian-independent effect on sleep. For example, acute exposure to light promotes sleep in nocturnal animals and wake in diurnal animals. The mechanisms whereby light directly influences sleep and arousal are not well understood. In this review, we discuss the direct effect of light on sleep at the level of the retina and hypothalamus in rodents. We review murine data from recent publications showing the roles of rod-, cone- and melanopsin-based photoreception on the initiation and maintenance of light-induced sleep. We also present hypotheses about hypothalamic mechanisms that have been advanced to explain the acute control of sleep by light. Specifically, we review recent studies assessing the roles of the ventrolateral preoptic area (VLPO) and the suprachiasmatic nucleus (SCN). We also discuss how light might differentially promote sleep and arousal in nocturnal and diurnal animals respectively. Lastly, we suggest new avenues for research on this topic which is still in its early stages. PMID:25140132

  1. Hypothalamic digoxin-mediated model for Parkinson's disease.

    PubMed

    Kurup, Ravi Kumar; Kurup, Parameswara Achutha

    2003-04-01

    The isoprenoid pathway produces four key metabolites important in cellular function--digoxin (endogenous membrane Na(+)-K+ ATPase inhibitor), dolichol (important in N-glycosylation of proteins), ubiquinone (free-radical scavenger), and cholesterol (component of cellular membranes). This study assessed the changes in the isoprenoid pathway and the consequences of its dysfunction in Parkinson's disease (PD). There was an elevation in plasma HMG CoA reductase activity, serum digoxin and dolichol levels, and a reduction in serum magnesium, RBC membrane Na(+)-K+ ATPase activity, and serum ubiquinone levels. Serum tryptophan, serotonin, strychnine, nicotine, and quinolinic acid were elevated, while tyrosine, morphine, dopamine, and noradrenaline were decreased. The total serum glycosaminoglycans (GAG) and glycosaminoglycan fractions (except chondroitin sulphates and hyaluronic acid), the activity of GAG degrading enzymes, carbohydrate residues of serum glycoproteins, the activity of glycohydrolase-beta galactosidase, and serum glycolipids were elevated. HDL cholesterol was reduced and free fatty acids increased. The RBC membrane glycosaminoglycans, hexose and fucose residues of glycoproteins and cholesterol were reduced, while phospholipid was increased. The activity of all serum free-radical scavenging enzymes, concentration of glutathione, alpha tocopherol, iron binding capacity, and ceruloplasmin decreased significantly in PD, while the concentration of serum lipid peroxidation products and nitric oxide increased. A dysfunctional isoprenoid pathway and related cascade are important in the pathogenesis of Parkinson's disease. A hypothalamic digoxin mediated model for Parkinson's disease is also postulated. PMID:12856480

  2. Dopamine Autoreceptor Regulation of a Hypothalamic Dopaminergic Network

    PubMed Central

    Stagkourakis, Stefanos; Kim, Hoseok; Lyons, David J.; Broberger, Christian

    2016-01-01

    Summary How autoreceptors contribute to maintaining a stable output of rhythmically active neuronal circuits is poorly understood. Here, we examine this issue in a dopamine population, spontaneously oscillating hypothalamic rat (TIDA) neurons, that underlie neuroendocrine control of reproduction and neuroleptic side effects. Activation of dopamine receptors of the type 2 family (D2Rs) at the cell-body level slowed TIDA oscillations through two mechanisms. First, they prolonged the depolarizing phase through a combination of presynaptic increases in inhibition and postsynaptic hyperpolarization. Second, they extended the discharge phase through presynaptic attenuation of calcium currents and decreased synaptic inhibition. Dopamine reuptake blockade similarly reconfigured the oscillation, indicating that ambient somatodendritic transmitter concentration determines electrical behavior. In the absence of D2R feedback, however, discharge was abolished by depolarization block. These results indicate the existence of an ultra-short feedback loop whereby neuroendocrine dopamine neurons tune network behavior to echoes of their own activity, reflected in ambient somatodendritic dopamine, and also suggest a mechanism for antipsychotic side effects. PMID:27149844

  3. Image-defined resolution following radiosurgery for hypothalamic hamartoma.

    PubMed

    O'Connor, Lucy; Curl-Roper, Thomas; Reeves, Nicola; Kemeny, Andras A; Josan, Vivek A

    2013-04-01

    The authors present the rare case of complete image-defined resolution of a hypothalamic hamartoma (HH) following Gamma Knife surgery (GKS). A 9-month-old girl presented with an episode of generalized tonic-clonic seizures. Magnetic resonance imaging revealed a left-sided HH, which remained radiologically stable. By 3 years of age the patient had a development delay of 12 months, and experienced 8 gelastic seizures per day while on 2 antiepileptic medications. Thirty-one months after presentation, the patient underwent elective GKS to treat the HH. She has since been seizure free for 22 months, while receiving 3 antiepileptic medications. Twelve months after radiosurgery, MRI revealed complete radiological resolution of the lesion. The authors discuss alternative management options for HH, including microsurgical resection, endoscopic disconnection, stereotactic radiofrequency thermocoagulation, and interstitial radiosurgery. Gamma Knife surgery is a minimally invasive procedure associated with a lower morbidity rate than that of published surgical results. The present case demonstrates the potential for complete image-defined resolution of an HH post-GKS, without long-term neurological sequelae, emphasizing the safety and efficacy of this therapeutic option for the control of epileptic seizures produced by small-volume, surgically inaccessible HHs. PMID:23373624

  4. Thyroid hormone is required for hypothalamic neurons regulating cardiovascular functions

    PubMed Central

    Mittag, Jens; Lyons, David J.; Sällström, Johan; Vujovic, Milica; Dudazy-Gralla, Susi; Warner, Amy; Wallis, Karin; Alkemade, Anneke; Nordström, Kristina; Monyer, Hannah; Broberger, Christian; Arner, Anders; Vennström, Björn

    2012-01-01

    Thyroid hormone is well known for its profound direct effects on cardiovascular function and metabolism. Recent evidence, however, suggests that the hormone also regulates these systems indirectly through the central nervous system. While some of the molecular mechanisms underlying the hormone’s central control of metabolism have been identified, its actions in the central cardiovascular control have remained enigmatic. Here, we describe a previously unknown population of parvalbuminergic neurons in the anterior hypothalamus that requires thyroid hormone receptor signaling for proper development. Specific stereotaxic ablation of these cells in the mouse resulted in hypertension and temperature-dependent tachycardia, indicating a role in the central autonomic control of blood pressure and heart rate. Moreover, the neurons exhibited intrinsic temperature sensitivity in patch-clamping experiments, providing a new connection between cardiovascular function and core temperature. Thus, the data identify what we believe to be a novel hypothalamic cell population potentially important for understanding hypertension and indicate developmental hypothyroidism as an epigenetic risk factor for cardiovascular disorders. Furthermore, the findings may be beneficial for treatment of the recently identified patients that have a mutation in thyroid hormone receptor α1. PMID:23257356

  5. Hypothalamic gene expression underlying pre-hibernation satiety.

    PubMed

    Schwartz, C; Hampton, M; Andrews, M T

    2015-03-01

    Prior to hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) enter a hypophagic period where food consumption drops by an average of 55% in 3 weeks. This occurs naturally, while the ground squirrels are in constant environmental conditions and have free access to food. Importantly, this transition occurs before exposure to hibernation conditions (5°C and constant darkness), so the ground squirrels are still maintaining a moderate level of activity. In this study, we used the Illumina HiSeq 2000 system to sequence the hypothalamic transcriptomes of ground squirrels before and after the autumn feeding transition to examine the genes underlying this extreme change in feeding behavior. The hypothalamus was chosen because it is known to play a role in the control and regulation of food intake and satiety. Overall, our analysis identified 143 genes that are significantly differentially expressed between the two groups. Specifically, we found five genes associated with feeding behavior and obesity (VGF, TRH, LEPR, ADIPOR2, IRS2) that are all upregulated during the hypophagic period, after the feeding transition has occurred. We also found that serum leptin significantly increases in the hypophagic group. Several of the genes associated with the natural autumnal feeding decline in 13-lined ground squirrels show parallels to signaling pathways known to be disrupted in human metabolic diseases, like obesity and diabetes. In addition, many other genes were identified that could be important for the control of food consumption in other animals, including humans. PMID:25640202

  6. Telemetric control of peripheral lipophagy by hypothalamic autophagy.

    PubMed

    Martinez-Lopez, Nuria; Singh, Rajat

    2016-08-01

    Autophagy maintains cellular quality control by degrading organelles, and cytosolic proteins and their aggregates in lysosomes. Autophagy also degrades lipid droplets (LD) through a process termed lipophagy. During lipophagy, LD are sequestered within autophagosomes and degraded by lysosomal acid lipases to generate free fatty acids that are β-oxidized for energy. Lipophagy was discovered in hepatocytes, and since then has been shown to function in diverse cell types. Whether lipophagy degrades LD in the major fat storing cell-the adipocyte-remained unclear. We have found that blocking autophagy in brown adipose tissues (BAT) by deleting the autophagy gene Atg7 in BAT MYF5 (myogenic factor 5)-positive progenitors increases basal lipid content in BAT and decreases lipid utilization during cold exposure-indicating that lipophagy contributes to lipohomeostasis in the adipose tissue. Surprisingly, knocking out Atg7 in hypothalamic proopiomelanocortin (POMC) neurons also blocks lipophagy in BAT and liver suggesting that specific neurons within the central nervous system (CNS) exert telemetric control over lipophagy in BAT and liver. PMID:27341145

  7. Analyses of rapid estrogen actions on rat ventromedial hypothalamic neurons.

    PubMed

    Kow, Lee-Ming; Pataky, Stefan; Dupré, Christophe; Phan, Anna; Martin-Alguacil, Nieves; Pfaff, Donald W

    2016-07-01

    Rapid estrogen actions are widely diverse across many cell types. We conducted a series of electrophysiological studies on single rat hypothalamic neurons and found that estradiol (E2) could rapidly and independently potentiate neuronal excitation/depolarizations induced by histamine (HA) and N-Methyl-d-Aspartate (NMDA). Now, the present whole-cell patch study was designed to determine whether E2 potentiates HA and NMDA depolarizations - mediated by distinctly different types of receptors - by the same or by different mechanisms. For this, the actions of HA, NMDA, as well as E2, were investigated first using various ion channel blockers and then by analyzing and comparing their channel activating characteristics. Results indicate that: first, both HA and NMDA depolarize neurons by inhibiting K(+) currents. Second, E2 potentiates both HA and NMDA depolarizations by enhancing the inhibition of K(+) currents, an inhibition caused by the two transmitters. Third, E2 employs the very same mechanism, the enhancement of K(+) current inhibition, thus to rapidly potentiate HA and NMDA depolarizations. These data are of behavioral importance, since the rapid E2 potentiation of depolarization synergizes with nuclear genomic actions of E2 to facilitate lordosis behavior, the primary female-typical reproductive behavior. PMID:27017919

  8. Somatostatin triggers rhythmic electrical firing in hypothalamic GHRH neurons

    PubMed Central

    Osterstock, Guillaume; Mitutsova, Violeta; Barre, Alexander; Granier, Manon; Fontanaud, Pierre; Chazalon, Marine; Carmignac, Danielle; Robinson, Iain C. A. F.; Low, Malcolm J.; Plesnila, Nikolaus; Hodson, David J.; Mollard, Patrice; Méry, Pierre-François

    2016-01-01

    Hypothalamic growth hormone-releasing hormone (GHRH) neurons orchestrate body growth/maturation and have been implicated in feeding responses and ageing. However, the electrical patterns that dictate GHRH neuron functions have remained elusive. Since the inhibitory neuropeptide somatostatin (SST) is considered to be a primary oscillator of the GH axis, we examined its acute effects on GHRH neurons in brain slices from male and female GHRH-GFP mice. At the cellular level, SST irregularly suppressed GHRH neuron electrical activity, leading to slow oscillations at the population level. This resulted from an initial inhibitory action at the GHRH neuron level via K+ channel activation, followed by a delayed, sst1/sst2 receptor-dependent unbalancing of glutamatergic and GABAergic synaptic inputs. The oscillation patterns induced by SST were sexually dimorphic, and could be explained by differential actions of SST on both GABAergic and glutamatergic currents. Thus, a tripartite neuronal circuit involving a fast hyperpolarization and a dual regulation of synaptic inputs appeared sufficient in pacing the activity of the GHRH neuronal population. These “feed-forward loops” may represent basic building blocks involved in the regulation of GHRH release and its downstream sexual specific functions. PMID:27072430

  9. Hypothalamic substrates of self-stimulation in cats.

    PubMed

    Wyrwicka, W; Clemente, C D; Chase, M H

    1986-09-01

    The purpose of this study was to gather anatomical data concerning sites for self-stimulation in the lateral hypothalamus in the cat. The study was conducted on 25 adult cats. In each cat, one to three monopolar stimulating electrodes were implanted bilaterally in the lateral hypothalamus in a region between sections Fr 10.0 and Fr 13.0, L 2.0 and L 5.0, and H -2.0 and H -6.0. A reference electrode was placed in the calvaria over the frontal sinus. Twenty-two of these cats learned to press a lever when each press was rewarded by a brief (0.3 s) electrical stimulus (2.0 to 7.0 V, 100/s, 1 ms duration per pulse) delivered to the hypothalamus. Postmortem anatomical analysis of the brains revealed that most of the positive rewarding sites were located in a midlateral hypothalamic zone, which included the medial forebrain bundle, and were localized to section Fr 11.5, between L 2.0 and L. 5.0, and H -3.0 and H -5.5. PMID:3743701

  10. Molecular features of hypothalamic plaques in Alzheimer's disease.

    PubMed Central

    Standaert, D. G.; Lee, V. M.; Greenberg, B. D.; Lowery, D. E.; Trojanowski, J. Q.

    1991-01-01

    The pathology of Alzheimer's disease (AD) involves subcortical as well as cortical structures. The authors have used immunohistochemical methods to study the molecular composition of AD plaques in the hypothalamus. In contrast to previous studies using histochemical methods, the authors observed large numbers of diffuse plaques in the AD hypothalamus labeled with an antiserum to the beta-amyloid, or A4 peptide, of the beta-amyloid precursor proteins (beta APPs), whereas A4-immunoreactive plaques were uncommon in the hypothalamus of patients without AD. Unlike plaques in the cortex and hippocampus of AD patients, hypothalamic plaques did not contain epitopes corresponding to other regions of the beta APPs, nor did they contain tau-, neurofilament-, or microtubule-associated protein-reactive epitopes, and did not disrupt the neuropil or produce astrogliosis. These findings demonstrate that there are substantial molecular and cellular differences in the pathologic features of AD in the hypothalamus compared with those observed in hippocampal and cortical structures, which may provide insight into the pathogenetic mechanisms of AD. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:1653521

  11. Paraventricular hypothalamic nucleus: axonal projections to the brainstem

    PubMed Central

    Geerling, Joel C.; Shin, Jung-Won; Chimenti, Peter C.; Loewy, Arthur D.

    2010-01-01

    The paraventricular hypothalamic nucleus (PVH) contains many neurons that innervate the brainstem, but information regarding their target sites remains incomplete. Here, we labeled neurons in the rat PVH with an anterograde axonal tracer, Phaseolus vulgaris leucoagglutinin (PHAL) and studied their descending projections in reference to specific neuronal subpopulations throughout the brainstem. While many of their target sites were identified previously, numerous new observations were made. Major findings include: (1) In the midbrain, the PVH projects lightly to the ventral tegmental area, Edinger-Westphal nucleus, ventrolateral periaqueductal gray matter, reticular formation, pedunculopontine tegmental nucleus, and dorsal raphe nucleus. (2) In the dorsal pons, the PVH projects heavily to the pre-locus coeruleus, yet very little to the catecholamine neurons in the locus coeruleus, and selectively targets the viscerosensory subregions of the parabrachial nucleus; (3) In the ventral medulla, the superior salivatory nucleus, retrotrapezoid nucleus, compact and external formations of the nucleus ambiguus, A1 and caudal C1 catecholamine neurons, and caudal pressor area receive dense axonal projections, generally exceeding the PVH projection to the rostral C1 region; (4) The medial nucleus of the solitary tract (including A2 noradrenergic and aldosterone-sensitive neurons) receives the most extensive projections of the PVH, substantially more than the dorsal vagal nucleus or area postrema. Our findings suggest that the PVH may modulate a range of homeostatic functions, including cerebral and ocular blood flow, corneal and nasal hydration, ingestive behavior, sodium intake, and glucose metabolism, as well as cardiovascular, gastrointestinal, and respiratory activities. PMID:20187136

  12. Epilepsy in hypothalamic hamartoma: clinical and EEG features.

    PubMed

    Harvey, A Simon; Freeman, Jeremy L

    2007-06-01

    Hypothalamic hamartoma (HH) is a congenital malformation of the hypothalamus that may be asymptomatic or manifest with precocious puberty or seizures. Gelastic seizures often begin early in life, even in the newborn period, being manifest by frequent attacks of inappropriate laughter resulting from seizure activity in the HH. The scalp electroencephalogram (EEG) is often normal in children with gelastic seizures, such that the diagnosis of epilepsy and the finding of a HH are often delayed. In a proportion of children with HH, there is an epileptic progression, in which complex partial seizures with frontal, temporal, and lateralized clinical features appear, usually with the appearance of focal slowing and epileptiform activity on the interictal EEG. Further progression may ensue with the appearance of tonic or atonic drop attacks, generalized tonic-clonic seizures, and epileptic spasms; rarely, infantile spasms may be the presenting seizure type. With the appearance of generalized seizures, the interictal EEG shows bilaterally synchronous and generalized epileptiform activity, often in abundance. The mechanism of this evolution is incompletely understood but neocortical seizure propagation and secondary epileptogenesis are believed to be important. Paralleling the development of the focal and generalized electroclinical manifestations in children with HH is usually slowing of development and the appearance of behavioral problems. Fortunately, many of these neurologic manifestations can be arrested, or reversed, with effective surgical treatment directed at the HH. PMID:17544948

  13. Ventromedial hypothalamic neurons control a defensive emotion state

    PubMed Central

    Kunwar, Prabhat S; Zelikowsky, Moriel; Remedios, Ryan; Cai, Haijiang; Yilmaz, Melis; Meister, Markus; Anderson, David J

    2015-01-01

    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. DOI: http://dx.doi.org/10.7554/eLife.06633.001 PMID:25748136

  14. Hypothalamic-Pituitary Function in Brain Death: A Review.

    PubMed

    Nair-Collins, Michael; Northrup, Jesse; Olcese, James

    2016-01-01

    The Uniform Determination of Death Act (UDDA) states that an individual is dead when "all functions of the entire brain" have ceased irreversibly. However, it has been questioned whether some functions of the hypothalamus, particularly osmoregulation, can continue after the clinical diagnosis of brain death (BD). In order to learn whether parts of the hypothalamus can continue to function after the diagnosis of BD, we performed 2 separate systematic searches of the MEDLINE database, corresponding to the functions of the posterior and anterior pituitary. No meta-analysis is possible due to nonuniformity in the clinical literature. However, some modest generalizations can reasonably be drawn from a narrative review and from anatomic considerations that explain why these findings should be expected. We found evidence suggesting the preservation of hypothalamic function, including secretion of hypophysiotropic hormones, responsiveness to anterior pituitary stimulation, and osmoregulation, in a substantial proportion of patients declared dead by neurological criteria. We discuss several possible explanations for these findings. We conclude by suggesting that additional clinical research with strict inclusion criteria is necessary and further that a more nuanced and forthright public dialogue is needed, particularly since standard diagnostic practices and the UDDA may not be entirely in accord. PMID:24692211

  15. Leucine minimizes denervation-induced skeletal muscle atrophy of rats through akt/mtor signaling pathways

    PubMed Central

    Ribeiro, Carolina B.; Christofoletti, Daiane C.; Pezolato, Vitor A.; de Cássia Marqueti Durigan, Rita; Prestes, Jonato; Tibana, Ramires A.; Pereira, Elaine C. L.; de Sousa Neto, Ivo V.; Durigan, João L. Q.; da Silva, Carlos A.

    2015-01-01

    The aim of the present study was to evaluate the effect of leucine treatment (0.30 mM) on muscle weight and signaling of myoproteins related to synthesis and degradation pathways of soleus muscle following seven days of complete sciatic nerve lesion. Wistar rats (n = 24) of 3–4 months of age (192 ± 23 g) were used. The animals were randomly distributed into four experimental groups (n = 6/group): control, treated with leucine (L), denervated (D) and denervated treated with leucine (DL). Dependent measures were proteins levels of AKT, AMPK, mTOR, and ACC performed by Western blot. Leucine induced a reduction in the phosphorylation of AMPK (p < 0.05) by 16% in the L and by 68% in the DL groups as compared with control group. Denervation increased AMPK by 24% in the D group as compared with the control group (p < 0.05). AKT was also modulated by denervation and leucine treatment, highlighted by the elevation of AKT phosphorylation in the D (65%), L (98%) and DL (146%) groups as compared with the control group (p < 0.05). AKT phosphorylation was 49% higher in the D group as compared with the DL group. Furthermore, denervation decreased mTOR phosphorylation by 29% in the D group as compared with the control group. However, leucine treatment induced an increase of 49% in the phosphorylation of mTOR in the L group as compared with the control group, and an increase of 154% in the DL as compared with the D group (p < 0.05). ACC phosphorylation was 20% greater in the D group than the control group. Furthermore, ACC in the soleus was 22% lower in the in the L group and 50% lower in the DL group than the respective control group (p < 0.05). In conclusion, leucine treatment minimized the deleterious effects of denervation on rat soleus muscle by increasing anabolic (AKT and mTOR) and decreasing catabolic (AMPK) pathways. These results may be interesting for muscle recovery following acute denervation, which may contribute to musculoskeletal rehabilitation after denervation

  16. 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.

  17. 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. PMID:27094036

  18. 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. PMID:24333966

  19. Regions of the Bacillus subtilis ilv-leu operon involved in regulation by leucine.

    PubMed Central

    Grandoni, J A; Fulmer, S B; Brizzio, V; Zahler, S A; Calvo, J M

    1993-01-01

    The ilv-leu operon of Bacillus subtilis is regulated in part by transcription attenuation. The cis-acting elements required for regulation by leucine lie within a 683-bp fragment of DNA from the region upstream of ilvB, the first gene of the operon. This fragment contains the ilv-leu promoter and 482 bp of the ilv-leu leader region. Spontaneous mutations that lead to increased expression of the operon were shown to lie in an imperfect inverted repeat encoding the terminator stem within the leader region. Mutations within the inverted repeat of the terminator destroyed most of the leucine-mediated repression. The remaining leucine-mediated repression probably resulted from a decrease in transcription initiation. A systematic analysis of other deletions within the ilv-leu leader region identified a 40-bp region required for the derepression that occurred during leucine limitation. This region lies within a potential RNA stem-and-loop structure that is probably required for leucine-dependent control. Deletion analysis also suggested that alternate secondary structures proximal to the terminator are involved in allowing transcription to proceed beyond the terminator. Additional experiments suggested that attenuation of the ilv-leu operon is not dependent on coupling translation to transcription of the leader region. Our data support a model proposed by Grundy and Henkin (F. J. Grundy and T. M. Henkin, Cell 74:475-482, 1993) in which uncharged tRNA acts as a positive regulatory factor to increase gene expression during amino acid limitation. Images PMID:8244927

  20. Growth hormone modulates hypothalamic inflammation in long-lived pituitary dwarf mice.

    PubMed

    Sadagurski, Marianna; Landeryou, Taylor; Cady, Gillian; Kopchick, John J; List, Edward O; Berryman, Darlene E; Bartke, Andrzej; Miller, Richard A

    2015-12-01

    Mice in which the genes for growth hormone (GH) or GH receptor (GHR(-/-) ) are disrupted from conception are dwarfs, possess low levels of IGF-1 and insulin, have low rates of cancer and diabetes, and are extremely long-lived. Median longevity is also increased in mice with deletion of hypothalamic GH-releasing hormone (GHRH), which leads to isolated GH deficiency. The remarkable extension of longevity in hypopituitary Ames dwarf mice can be reversed by a 6-week course of GH injections started at the age of 2 weeks. Here, we demonstrate that mutations that interfere with GH production or response, in the Snell dwarf, Ames dwarf, or GHR(-/-) mice lead to reduced formation of both orexigenic agouti-related peptide (AgRP) and anorexigenic proopiomelanocortin (POMC) projections to the main hypothalamic projection areas: the arcuate nucleus (ARH), paraventricular nucleus (PVH), and dorsomedial nucleus (DMH). These mutations also reduce hypothalamic inflammation in 18-month-old mice. GH injections, between 2 and 8 weeks of age, reversed both effects in Ames dwarf mice. Disruption of GHR specifically in liver (LiGHRKO), a mutation that reduces circulating IGF-1 but does not lead to lifespan extension, had no effect on hypothalamic projections or inflammation, suggesting an effect of GH, rather than peripheral IGF-1, on hypothalamic development. Hypothalamic leptin signaling, as monitored by induction of pStat3, is not impaired by GHR deficiency. Together, these results suggest that early-life disruption of GH signaling produces long-term hypothalamic changes that may contribute to the longevity of GH-deficient and GH-resistant mice. PMID:26268661

  1. Therapeutic Neuroendocrine Agonist and Antagonist Analogs of Hypothalamic Neuropeptides as Modulators of the Hypothalamic-Pituitary-Gonadal Axis.

    PubMed

    Newton, Claire L; Anderson, Ross C; Millar, Robert P

    2016-01-01

    Reproductive hormones play a role at all stages of life and affect most tissues of the body. Gonadotropin-releasing hormone (GnRH) synthesized in the hypothalamus stimulates the secretion of gonadotropins which in turn stimulate gonadal sex hormone production and gamete formation. This hypothalamic-pituitary-gonadal (HPG) axis has, therefore, been the target for the development of numerous drugs which regulate it at various points. These include sex steroid agonists and antagonists, inhibitors of sex steroid biosynthesis, and GnRH agonists and antagonists, which have found extensive applications in treating numerous conditions such as precocious puberty, delayed puberty, prostate cancer, benign prostatic hyperplasia, endometriosis, uterine fibroids and also in in vitro fertilization protocols. The novel neuroendocrine peptides, kisspeptin (KP) and neurokinin B (NKB), were recently discovered as upstream regulators of GnRH, and inactivating mutations of KP and NKB ligands or receptors result in a failure to progress through puberty. Agonists and antagonists of KP and NKB are being developed as more subtle modulators of the HPG axis. These new drugs offer additional and alternative therapeutic options in pediatric and adult hormone-dependent diseases. PMID:26684214

  2. Medial hypothalamic 5-hydroxytryptamine (5-HT)1A receptors regulate neuroendocrine responses to stress and exploratory locomotor activity: application of recombinant adenovirus containing 5-HT1A sequences.

    PubMed

    Li, Qian; Holmes, Andrew; Ma, Li; Van de Kar, Louis D; Garcia, Francisca; Murphy, Dennis L

    2004-12-01

    Our previous studies found that serotonin transporter (SERT) knock-out mice showed increased sensitivity to minor stress and increased anxiety-like behavior but reduced locomotor activity. These mice also showed decreased density of 5-hydroxytryptamine (5-HT1A) receptors in the hypothalamus, amygdala, and dorsal raphe. To evaluate the contribution of hypothalamic 5-HT1A receptors to these phenotypes of SERT knock-out mice, two studies were conducted. Recombinant adenoviruses containing 5-HT1A sense and antisense sequences (Ad-1AP-sense and Ad-1AP-antisense) were used to manipulate 5-HT1A receptors in the hypothalamus. The expression of the 5-HT1A genes is controlled by the 5-HT1A promoter, so that they are only expressed in 5-HT1A receptor-containing cells. (1) Injection of Ad-1AP-sense into the hypothalamus of SERT knock-out mice restored 5-HT1A receptors in the medial hypothalamus; this effect was accompanied by elimination of the exaggerated adrenocorticotropin responses to a saline injection (minor stress) and reduced locomotor activity but not by a change in increased exploratory anxiety-like behavior. (2) To further confirm the observation in SERT-/- mice, Ad-1AP-antisense was injected into the hypothalamus of normal mice. The density and the function of 5-HT1A receptors in the medial hypothalamus were significantly reduced in Ad-1AP-antisense-treated mice. Compared with the control group (injected with Ad-track), Ad-1A-antisense-treated mice showed a significant reduction in locomotor activity, but again no changes in exploratory anxiety-like behaviors, tested by elevated plus-maze and open-field tests. Thus, the present results demonstrate that medial hypothalamic 5-HT1A receptors regulate stress responses and locomotor activity but may not regulate exploratory anxiety-like behaviors. PMID:15574737

  3. Effect of strength training session on plasma amino acid concentration following oral ingestion of leucine, BCAAs or glutamine in men.

    PubMed

    Mero, Antti; Leikas, Anne; Knuutinen, Juha; Hulmi, Juha J; Kovanen, Vuokko

    2009-01-01

    We examined the acute effects of a 1-h strength training session (STS) on plasma amino acid concentration following orally ingestion of leucine, branched-chain amino acids (BCAAs) or glutamine in nine physically active men who participated in double-blinded and randomised experiments. The subjects took placebo, leucine, BCAAs, or glutamine capsules (50 mg/kg) in either rest (REST) or STS condition. Blood samples were taken before and at 30, 60, 90, and 120 min after the beginning of the treatment and they were assayed for plasma amino acids with HPLC. Following both leucine and BCAA ingestion the peak concentration of leucine was similar at rest (524 +/- 46 and 530 +/- 29 nmol/ml, respectively) and similar after STS (398 +/- 43 and 387 +/- 46 nmol/ml, respectively) but the rest and STS concentrations differed from each other (P < 0.01-0.001). The modelled polynomial data for the leucine treatment showed that the peak concentration of leucine occurred at 67 min at rest and at 90 min in STS (difference between REST and STS: P = 0.012). For the BCAA treatment the polynomial data showed that the peak concentration of leucine occurred at 72 min at rest and at 78 min in STS (P = 0.067). The peak concentration of glutamine was similar in both rest and STS condition and occurred at 60 min at rest and at 57 min in STS. In conclusion, 1-h of STS slows the increase in the peak concentration of plasma leucine similarly after oral ingestion of leucine or BCAAs but after oral ingestion of glutamine it has no slowing effect on glutamine concentration. PMID:19015870

  4. Excess leucine intake enhances muscle anabolic signaling but not net protein anabolism in young men and women.

    PubMed

    Glynn, Erin L; Fry, Christopher S; Drummond, Micah J; Timmerman, Kyle L; Dhanani, Shaheen; Volpi, Elena; Rasmussen, Blake B

    2010-11-01

    Essential amino acids (EAA) stimulate skeletal muscle protein synthesis (MPS) in humans. Leucine may have a greater stimulatory effect on MPS than other EAA and/or decrease muscle protein breakdown (MPB). To determine the effect of 2 different leucine concentrations on muscle protein turnover and associated signaling, young men (n = 6) and women (n = 8) ingested 10 g EAA in 1 of 2 groups: composition typical of high quality proteins (CTRL; 1.8 g leucine) or increased leucine concentration (LEU; 3.5 g leucine). Participants were studied for 180 min postingestion. Fractional synthetic rate and leg phenylalanine and leucine kinetics were assessed on muscle biopsies using stable isotopic techniques. Signaling was determined by immunoblotting. Arterial leucine concentration and delivery to the leg increased in both groups and was significantly higher in LEU than in CTRL; however, transport into the muscle and intracellular availability did not differ between groups. MPS increased similarly in both groups 60 min postingestion. MPB decreased at 60 min only in LEU, but net muscle protein balance improved similarly. Components of mammalian target of rapamycin (mTOR) signaling were improved in LEU, but no changes were observed in ubiquitin-proteasome system signaling. Changes in light chain 3 and mTOR association with Unc-51-like kinase 1 indicate autophagy decreased more in LEU. We conclude that in 10 g of EAA, the leucine content typical of high quality proteins (~1.8 g) is sufficient to induce a maximal skeletal muscle protein anabolic response in young adults, but leucine may play a role in autophagy regulation. PMID:20844186

  5. Gamma knife surgery for epilepsy related to hypothalamic hamartomas.

    PubMed

    Régis, Jean; Scavarda, Didier; Tamura, Manabu; Villeneuve, Nathalie; Bartolomei, Fabrice; Brue, Thierry; Morange, Isabelle; Dafonseca, David; Chauvel, Patrick

    2007-06-01

    Numerous neurosurgical approaches are available for children presenting with hypothalamic hamartomas (HHs) associated with severe epilepsy. A concern regarding the impairment of short-term memory after resective surgery is promoting the exploration of less invasive alternatives like radiosurgery. Gamma knife radiosurgery (GKS) can lead to a real reversal of the epileptic encephalopathy. Three years after radiosurgery, 60% of the children have an excellent result with complete seizure cessation in 40% and rare nondisabling seizures in 20%, often in association with dramatic behavioral and cognitive improvement. No permanent neurologic complications have thus far been reported. Rare transient cases of poikilothermia have been observed. GKS is clearly the safer approach for these difficult patients. Young patients with severe epilepsy and neurocognitive comorbidity must be treated by using a curative approach as early as possible. Topological type (according to our original classification) is the major feature for selection of the best treatment strategy. Type I HH deeply embedded in the hypothalamus is treated safely and efficiently by GKS. Type II HH can be resected by either endoscopic or transcallosal approaches or treated by GKS depending on the parent's choice and severity of epilepsy. In small type III HH, GKS is the safer procedure because of the very close relationship to the fornix and mammillary bodies. Types V (rarely epileptic) and IV are frequently operable by disconnection. Very large type VI (or mixed type) with a large component above the floor of the third ventricle must be disconnected, and then the upper remnant is best treated by GKS using a staged technique. Overall, when the lesion is sufficiently small, GKS offers a rate of seizure control comparable to microsurgery but with much lower risk. The disadvantage of radiosurgery is its delayed action. Longer follow-up is mandatory for a reliable evaluation of the role of GKS. PMID:17544950

  6. Hypothalamic contribution to sleep-wake cycle development.

    PubMed

    Karlsson, K A; Kreider, J C; Blumberg, M S

    2004-01-01

    Infant mammals cycle rapidly between sleep and wakefulness and only gradually does a more consolidated sleep pattern develop. The neural substrates responsible for this consolidation are unknown. To establish a reliable measure of sleep-wake cyclicity in infant rats, nuchal muscle tone was measured in 2-, 5-, and 8-day-old rats, as were motor behaviors associated with sleep (i.e. myoclonic twitching) and wakefulness (e.g. kicking, stretching). Sleep-wake cycles of 2-day-old rats were characterized by short periods of muscle atonia followed by equally short periods of high tone. In 8-day-olds, sleep periods lengthened significantly and disproportionately in relation to awake periods. Next, locus coeruleus (LC) lesions in 8-day-olds resulted in rapid sleep-wake cycling similar to that exhibited by 2-day-olds; in addition, LC lesions had no effect on the duration of awake periods. Finally, transections caudal, but not rostral, to the anterior hypothalamus also reinstated rapid cycling in 8-day-olds, again without affecting the duration of awake periods. This last finding implicates neural structures within the anterior hypothalamus (e.g. ventrolateral preoptic area) in the modulation of sleep-wake cyclicity. The temporal coherence of atonia and myoclonic twitching was not disrupted by any of the manipulations. These results suggest the presence of a bistable mesopontine circuit governing rapid sleep-wake cycling that does not include the LC and that comes increasingly under hypothalamic control during the first postnatal week. This circuit may represent a basic building block with which other sleep components become integrated during ontogeny. PMID:14698764

  7. Hypothalamic-pituitary-adrenal axis function in ankylosing spondylitis

    PubMed Central

    Imrich, R; Rovensky, J; Zlnay, M; Radikova, Z; Macho, L; Vigas, M; Koska, J

    2004-01-01

    Objective: To assess basal function and responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis in patients with ankylosing spondylitis during dynamic testing. Methods: Insulin induced hypoglycaemia (IIH) (Actrapid HM 0.1 IU/kg, as intravenous bolus) was induced in 17 patients and 11 healthy controls matched for age, sex, and body mass index. Concentrations of glucose, adrenocorticotrophic hormone (ACTH), cortisol, insulin, dehydroepiandrosterone sulphate (DHEAS), 17α-hydroxyprogesterone, interleukin 6 (IL-6), and tumour necrosis factor α (TNFα) were determined in plasma. Results: Comparable basal cortisol levels were found in the two groups, with a trend to be lower in ankylosing spondylitis. In the ankylosing spondylitis group, there were higher concentrations of IL-6 (mean (SEM): 16.6 (2.8) pg/ml v 1.41 (0.66) pg/ml in controls; p<0.001) and TNFα (8.5 (1.74) pg/ml v 4.08 (0.42) pg/ml in controls; p<0.01). Glucose, insulin, ACTH, DHEAS, and 17α-hydroxyprogesterone did not differ significantly from control. The IIH test was carried out successfully in 11 of the 17 patients with ankylosing spondylitis, and the ACTH and cortisol responses were comparable with control. General linear modelling showed a different course of glycaemia (p = 0.041) in the ankylosing spondylitis patients who met the criteria for a successful IIH test compared with the controls. Conclusions: The results suggest there is no difference in basal HPA axis activity and completely preserved responsiveness of the HPA axis in patients with ankylosing spondylitis. The interpretation of the different course of glycaemia during IIH in ankylosing spondylitis requires further investigation. PMID:15140773

  8. Sex-specific effects of androgen and estrogen on proliferation of the embryonic chicken hypothalamic neurons.

    PubMed

    Cao, Ailing; Zhang, Caiqiao

    2007-04-01

    Effects of androgen and estrogen on proliferation of hypothalamic neurons were evaluated by a chicken hypothalamic neuron-glia coculture model. Hypothalamic cells were dispersed from 17-day-old embryos and challenged with testosterone (T) and 17beta-estradiol (E2) alone or combined with androgen receptor antagonist flutamide, estrogen receptor antagonist tamoxifen, or aromatase inhibitor letrozole for 48 h. The neuron number was counted and the proliferating cells were identified by immunocytochemistry of proliferating cell nuclear antigen (PCNA) and 5-bromo-2-deoxyuridine (BrdU) incorporation. Results showed that both E2 and T stimulated proliferation of hypothalamic neurons. E2 showed more intensive effect on females and this promoting effect was abrogated by tamoxifen. T played more intensive effect on males and the effect was inhibited by flutamide, tamoxifen, or letrozole. The above results indicated that E2 stimulated neuron proliferation through estrogenic actions with more sensitive effect on females and T promoted neuron proliferation through both androgenic and estrogenic actions with more intense effect on males. These observations suggested that steroid hormones influence the proliferation of hypothalamic neurons in a sexually dimorphic manner during the development of chicken embryos. PMID:17873328

  9. Hypothalamic Response to the Chemo-Signal Androstadienone in Gender Dysphoric Children and Adolescents

    PubMed Central

    Burke, Sarah M.; Cohen-Kettenis, Peggy T.; Veltman, Dick J.; Klink, Daniel T.; Bakker, Julie

    2014-01-01

    The odorous steroid androstadienone, a putative male chemo-signal, was previously reported to evoke sex differences in hypothalamic activation in adult heterosexual men and women. In order to investigate whether puberty modulated this sex difference in response to androstadienone, we measured the hypothalamic responsiveness to this chemo-signal in 39 pre-pubertal and 41 adolescent boys and girls by means of functional magnetic resonance imaging. We then investigated whether 36 pre-pubertal children and 38 adolescents diagnosed with gender dysphoria (GD; DSM-5) exhibited sex-atypical (in accordance with their experienced gender), rather than sex-typical (in accordance with their natal sex) hypothalamic activations during olfactory stimulation with androstadienone. We found that the sex difference in responsiveness to androstadienone was already present in pre-pubertal control children and thus likely developed during early perinatal development instead of during sexual maturation. Adolescent girls and boys with GD both responded remarkably like their experienced gender, thus sex-atypical. In contrast, pre-pubertal girls with GD showed neither a typically male nor female hypothalamic activation pattern and pre-pubertal boys with GD had hypothalamic activations in response to androstadienone that were similar to control boys, thus sex-typical. We present here a unique data set of boys and girls diagnosed with GD at two different developmental stages, showing that these children possess certain sex-atypical functional brain characteristics and may have undergone atypical sexual differentiation of the brain. PMID:24904525

  10. Decreased quality of life in children with hypothalamic hamartoma and treatment-resistant epilepsy.

    PubMed

    Park, Cleo; Wethe, Jennifer V; Kerrigan, John F

    2013-01-01

    We evaluated health-related quality of life in patients with hypothalamic hamartoma, to see how it differs from that of children with more common neurologic disorders. We used the PedsQL 4.0, along with the Child Behavior Checklist, Hague Seizure Severity Scale, and Side Effects Scale, to evaluate presurgical patients with hypothalamic hamartoma and epilepsy (n = 21). The results were compared with those of age-matched cohorts with migraine (n = 19) and Benign Epilepsy with Central Temporal Spikes (n = 11). In comparison with the migraine group, the patients with hypothalamic hamartoma had decreased health-related quality of life across all domains of the PedsQL 4.0. Compared with the benign epilepsy group, the hypothalamic hamartoma cohort has a significantly lower score in School Function. Comorbid psychomotor retardation was predictive of lower quality of life. Research examining the efficacy of recently developed surgical treatments for hypothalamic hamartoma should include health-related quality of life as an outcome measure. PMID:22496118

  11. Leucine Supplementation Improves Acquired Growth Hormone Resistance in Rats with Protein-Energy Malnutrition

    PubMed Central

    Wang, Xinying; Zhao, Jie; Wan, Xiao; Zhang, Li; Wu, Chao; Li, Ning; Li, Jieshou

    2015-01-01

    Background Protein-energy malnutrition (PEM) can lead to growth hormone (GH) resistance. Leucine supplementation diets have been shown to increase protein synthesis in muscles. Our study aimed at investigating if long-term leucine supplementation could modulate GH-insulin-like growth factor (IGF)-1 system function and mammalian target of rapamycin (mTOR)-related signal transduction in skeletal muscles in a rat model of severe malnutrition. Methodology/Principal Findings Male Sprague-Dawley rats (n = 50; weight, 302 ± 5 g) were divided into 5 treatment groups, including 2 control groups (a normal control group that was fed chow and ad libitum water [CON, n = 10] and a malnourished control group [MC, n = 10] that was fed a 50% chow diet). After undergoing a weight loss stage for 4 weeks, rats received either the chow diet (MC-CON, n = 10), the chow diet supplemented with low-dose leucine (MC-L, n = 10), or the chow diet supplemented with high-dose leucine (MC-H, n = 10) for 2 weeks. The muscle masses of the gastrocnemius, soleus, and extensor digitorum longus were significantly reduced in the MC group. Re-feeding increased muscle mass, especially in the MC-L and MC-H groups. In the MC group, serum IGF-1, IGF-binding protein (IGFBP)-3, and hepatic growth hormone receptor (GHR) levels were significantly decreased and phosphorylation of the downstream anabolic signaling effectors protein kinase B (Akt), mTOR, and ribosomal protein S6 kinase 1 (S6K1) were significantly lower than in other groups. However, serum IGF-1 and IGF binding protein (IGFBP)-3 concentrations and hepatic growth hormone receptor (GHR) levels were significantly higher in the MC-L and MC-H groups than in the MC-CON group, and serum IGFBP-1 levels was significantly reduced in the MC-L and MC-H groups. These changes were consistent with those observed for hepatic mRNA expression levels. Phosphorylation of the downstream anabolic signaling effectors Akt, mTOR, and S6K1 were also significantly higher in

  12. N-acetyl-L-leucine accelerates vestibular compensation after unilateral labyrinthectomy by action in the cerebellum and thalamus.

    PubMed

    Günther, Lisa; Beck, Roswitha; Xiong, Guoming; Potschka, Heidrun; Jahn, Klaus; Bartenstein, Peter; Brandt, Thomas; Dutia, Mayank; Dieterich, Marianne; Strupp, Michael; la Fougère, Christian; Zwergal, Andreas

    2015-01-01

    An acute unilateral vestibular lesion leads to a vestibular tone imbalance with nystagmus, head roll tilt and postural imbalance. These deficits gradually decrease over days to weeks due to central vestibular compensation (VC). This study investigated the effects of i.v. N-acetyl-DL-leucine, N-acetyl-L-leucine and N-acetyl-D-leucine on VC using behavioural testing and serial [18F]-Fluoro-desoxyglucose ([18F]-FDG)-μPET in a rat model of unilateral chemical labyrinthectomy (UL). Vestibular behavioural testing included measurements of nystagmus, head roll tilt and postural imbalance as well as sequential whole-brain [18F]-FDG-μPET was done before and on days 1,3,7 and 15 after UL. A significant reduction of postural imbalance scores was identified on day 7 in the N-acetyl-DL-leucine (p < 0.03) and the N-acetyl-L-leucine groups (p < 0.01), compared to the sham treatment group, but not in the N-acetyl-D-leucine group (comparison for applied dose of 24 mg i.v. per rat, equivalent to 60 mg/kg body weight, in each group). The course of postural compensation in the DL- and L-group was accelerated by about 6 days relative to controls. The effect of N-acetyl-L-leucine on postural compensation depended on the dose: in contrast to 60 mg/kg, doses of 15 mg/kg and 3.75 mg/kg had no significant effect. N-acetyl-L-leucine did not change the compensation of nystagmus or head roll tilt at any dose. Measurements of the regional cerebral glucose metabolism (rCGM) by means of μPET revealed that only N-acetyl-L-leucine but not N-acetyl-D-leucine caused a significant increase of rCGM in the vestibulocerebellum and a decrease in the posterolateral thalamus and subthalamic region on days 3 and 7. A similar pattern was found when comparing the effect of N-acetyl-L-leucine on rCGM in an UL-group and a sham UL-group without vestibular damage. In conclusion, N-acetyl-L-leucine improves compensation of postural symptoms after UL in a dose-dependent and specific manner, most likely by

  13. N-Acetyl-L-Leucine Accelerates Vestibular Compensation after Unilateral Labyrinthectomy by Action in the Cerebellum and Thalamus

    PubMed Central

    Xiong, Guoming; Potschka, Heidrun; Jahn, Klaus; Bartenstein, Peter; Brandt, Thomas; Dutia, Mayank; Dieterich, Marianne; Strupp, Michael; la Fougère, Christian; Zwergal, Andreas

    2015-01-01

    An acute unilateral vestibular lesion leads to a vestibular tone imbalance with nystagmus, head roll tilt and postural imbalance. These deficits gradually decrease over days to weeks due to central vestibular compensation (VC). This study investigated the effects of i.v. N-acetyl-DL-leucine, N-acetyl-L-leucine and N-acetyl-D-leucine on VC using behavioural testing and serial [18F]-Fluoro-desoxyglucose ([18F]-FDG)-μPET in a rat model of unilateral chemical labyrinthectomy (UL). Vestibular behavioural testing included measurements of nystagmus, head roll tilt and postural imbalance as well as sequential whole-brain [18F]-FDG-μPET was done before and on days 1,3,7 and 15 after UL. A significant reduction of postural imbalance scores was identified on day 7 in the N-acetyl-DL-leucine (p < 0.03) and the N-acetyl-L-leucine groups (p < 0.01), compared to the sham treatment group, but not in the N-acetyl-D-leucine group (comparison for applied dose of 24 mg i.v. per rat, equivalent to 60 mg/kg body weight, in each group). The course of postural compensation in the DL- and L-group was accelerated by about 6 days relative to controls. The effect of N-acetyl-L-leucine on postural compensation depended on the dose: in contrast to 60 mg/kg, doses of 15 mg/kg and 3.75 mg/kg had no significant effect. N-acetyl-L-leucine did not change the compensation of nystagmus or head roll tilt at any dose. Measurements of the regional cerebral glucose metabolism (rCGM) by means of μPET revealed that only N-acetyl-L-leucine but not N-acetyl-D-leucine caused a significant increase of rCGM in the vestibulocerebellum and a decrease in the posterolateral thalamus and subthalamic region on days 3 and 7. A similar pattern was found when comparing the effect of N-acetyl-L-leucine on rCGM in an UL-group and a sham UL-group without vestibular damage. In conclusion, N-acetyl-L-leucine improves compensation of postural symptoms after UL in a dose-dependent and specific manner, most likely by

  14. 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)

  15. Ontogeny of hypothalamic glucocorticoid receptor-mediated inhibition of the hypothalamic-pituitary-adrenal axis in mice.

    PubMed

    Laryea, Gloria; Arnett, Melinda; Muglia, Louis J

    2015-01-01

    Glucocorticoid receptors (GR) in the paraventricular nucleus of the hypothalamus (PVN) are important regulators of negative feedback regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Previous evaluation of endogenous PVN GR function in adult mice demonstrated that mice with loss of GR exon 3 in the PVN (Sim1Cre-GRe3Δ) have a hyperactive HPA axis, growth impairment and metabolic disruptions. Here, we hypothesized that lack of negative feedback inhibition of the HPA axis through PVN GR, as demonstrated through loss of PVN GR early in life, will have developmental-stage-specific consequences. Immunofluorescence revealed that Sim1Cre-GRe3Δ mice display PVN GR loss as early as post-natal day 2 compared to control mice. Sim1Cre-GRe3Δ mice compared to controls also displayed increased corticotropin-releasing hormone (CRH) mRNA in the PVN at post-natal day 10, as shown by in situ hybridization. Corticosterone radioimmunoassay revealed that the disruptions in PVN GR and CRH expression led to elevated basal corticosterone secretion in male Sim1Cre-GRe3Δ mice by early adolescence and increased stress-induced (restraint) corticosterone secretion in late adolescence into adulthood. In comparison, female Sim1Cre-GRe3Δ mice did not display corticosterone disruption until adulthood. Circadian rhythmicity of corticosterone secretion was normal for male and female mice at all age groups regardless of genotype with one exception. In late adolescence, female Sim1Cre-GRe3Δ mice had disrupted circadian corticosterone secretion due to significantly elevated circulating levels at nadir. We conclude that PVN GR function matures at an earlier developmental time point in male than in female mice and thus leads to later differential stress responsiveness between sexes. PMID:26068518

  16. Hypothalamic TLR2 triggers sickness behavior via a microglia-neuronal axis.

    PubMed

    Jin, Sungho; Kim, Jae Geun; Park, Jeong Woo; Koch, Marco; Horvath, Tamas L; Lee, Byung Ju

    2016-01-01

    Various pathophysiologic mechanisms leading to sickness behaviors have been proposed. For example, an inflammatory process in the hypothalamus has been implicated, but the signaling modalities that involve inflammatory mechanisms and neuronal circuit functions are ill-defined. Here, we show that toll-like receptor 2 (TLR2) activation by intracerebroventricular injection of its ligand, Pam3CSK4, triggered hypothalamic inflammation and activation of arcuate nucleus microglia, resulting in altered input organization and increased activity of proopiomelanocortin (POMC) neurons. These animals developed sickness behavior symptoms, including anorexia, hypoactivity, and hyperthermia. Antagonists of nuclear factor kappa B (NF-κB), cyclooxygenase pathway and melanocortin receptors 3/4 reversed the anorexia and body weight loss induced by TLR2 activation. These results unmask an important role of TLR2 in the development of sickness behaviors via stimulation of hypothalamic microglia to promote POMC neuronal activation in association with hypothalamic inflammation. PMID:27405276

  17. Hypothalamic TLR2 triggers sickness behavior via a microglia-neuronal axis

    PubMed Central

    Jin, Sungho; Kim, Jae Geun; Park, Jeong Woo; Koch, Marco; Horvath, Tamas L.; Lee, Byung Ju

    2016-01-01

    Various pathophysiologic mechanisms leading to sickness behaviors have been proposed. For example, an inflammatory process in the hypothalamus has been implicated, but the signaling modalities that involve inflammatory mechanisms and neuronal circuit functions are ill-defined. Here, we show that toll-like receptor 2 (TLR2) activation by intracerebroventricular injection of its ligand, Pam3CSK4, triggered hypothalamic inflammation and activation of arcuate nucleus microglia, resulting in altered input organization and increased activity of proopiomelanocortin (POMC) neurons. These animals developed sickness behavior symptoms, including anorexia, hypoactivity, and hyperthermia. Antagonists of nuclear factor kappa B (NF-κB), cyclooxygenase pathway and melanocortin receptors 3/4 reversed the anorexia and body weight loss induced by TLR2 activation. These results unmask an important role of TLR2 in the development of sickness behaviors via stimulation of hypothalamic microglia to promote POMC neuronal activation in association with hypothalamic inflammation. PMID:27405276

  18. Early changes in the hypothalamic region in prodromal Huntington disease revealed by MRI analysis

    PubMed Central

    Soneson, Charlotte; Fontes, Magnus; Zhou, Yongxia; Denisov, Vladimir; Paulsen, Jane S.; Kirik, Deniz; Petersén, Åsa

    2010-01-01

    Huntington disease (HD) is a fatal neurodegenerative disorder caused by an expanded CAG repeat. Its length can be used to estimate the time of clinical diagnosis, which is defined by overt motor symptoms. Non-motor symptoms begin before motor onset, and involve changes in hypothalamus-regulated functions such as sleep, emotion and metabolism. Therefore we hypothesized that hypothalamic changes occur already prior to the clinical diagnosis. We performed voxel-based morphometry and logistic regression analyses of cross-sectional MR images from 220 HD gene carriers and 75 controls in the Predict-HD study. We show that changes in the hypothalamic region are detectable before clinical diagnosis and that its grey matter contents alone is sufficient to distinguish HD gene carriers from control cases. In conclusion, our study shows, for the first time, that alterations in grey matter contents in the hypothalamic region occur at least a decade before clinical diagnosis in HD using MRI. PMID:20682340

  19. Episodic hormone secretion during sleep in Kleine-Levin syndrome: evidence for hypothalamic dysfunction.

    PubMed

    Gadoth, N; Dickerman, Z; Bechar, M; Laron, Z; Lavie, P

    1987-01-01

    "Acute" hypothalamic-pituitary function tests including insulin tolerance test, LRH, ACTH and TRH stimulation tests and nocturnal secretory pattern of human growth hormone, 11-OHCS, prolactin, FSH, LH and TSH were studied in a 23-year-old male with Kleine-Levin syndrome during the course of a typical hypersomnic attack. The "acute" tests revealed paradoxical growth-hormone response to TRH stimulation, borderline high basal plasma prolactin levels with normal response to TRH. The hormonal secretory pattern during sleep revealed abnormalities in LH, 11-OHCS and prolactin secretion. These together with the results of the "acute" tests are indicative of an abnormality in the hypothalamic regulation of various pituitary hormones. This observation may indeed be the first laboratory demonstration confirming a long-standing hypothesis that Kleine-Levin syndrome is related to hypothalamic dysfunction. PMID:3477962

  20. Early changes in the hypothalamic region in prodromal Huntington disease revealed by MRI analysis.

    PubMed

    Soneson, Charlotte; Fontes, Magnus; Zhou, Yongxia; Denisov, Vladimir; Paulsen, Jane S; Kirik, Deniz; Petersén, Asa

    2010-12-01

    Huntington disease (HD) is a fatal neurodegenerative disorder caused by an expanded CAG repeat. Its length can be used to estimate the time of clinical diagnosis, which is defined by overt motor symptoms. Non-motor symptoms begin before motor onset, and involve changes in hypothalamus-regulated functions such as sleep, emotion and metabolism. Therefore we hypothesized that hypothalamic changes occur already prior to the clinical diagnosis. We performed voxel-based morphometry and logistic regression analyses of cross-sectional MR images from 220 HD gene carriers and 75 controls in the Predict-HD study. We show that changes in the hypothalamic region are detectable before clinical diagnosis and that its grey matter contents alone are sufficient to distinguish HD gene carriers from control cases. In conclusion, our study shows, for the first time, that alterations in grey matter contents in the hypothalamic region occur at least a decade before clinical diagnosis in HD using MRI. PMID:20682340

  1. Dimerization mediated through a leucine zipper activates the oncogenic potential of the met receptor tyrosine kinase.

    PubMed Central

    Rodrigues, G A; Park, M

    1993-01-01

    Oncogenic activation of the met (hepatocyte growth factor/scatter factor) receptor tyrosine kinase involves a genomic rearrangement that generates a hybrid protein containing tpr-encoded sequences at its amino terminus fused directly to the met-encoded receptor kinase domain. Deletion of Tpr sequences abolishes the transforming ability of this protein, implicating this region in oncogenic activation. We demonstrate, by site-directed mutagenesis and coimmunoprecipitation experiments, that a leucine zipper motif within Tpr mediates dimerization of the tpr-met product and is essential for the transforming activity of the met oncogene. By analogy with ligand-stimulated activation of receptor tyrosine kinases, we propose that constitutive dimerization mediated by a leucine zipper motif within Tpr is responsible for oncogenic activation of the Met kinase. The possibility that this mechanism of activation represents a paradigm for a class of receptor tyrosine kinase oncogenes activated by DNA rearrangement is discussed. Images PMID:8413267

  2. Anatomical localization of leucine-rich repeat kinase 2 in mouse brain.

    PubMed

    Melrose, H; Lincoln, S; Tyndall, G; Dickson, D; Farrer, M

    2006-01-01

    Mutations in leucine-rich repeat kinase 2 (LRRK2) have recently been identified in autosomal dominant late-onset Parkinson's disease. Expression of LRRK2 has previously been reported in brain; however, no precise anatomical information is yet available. We have performed in situ hybridization and quantitative reverse transcription polymerase chain reaction to map LRRK2 mRNA expression in mouse brain. We find LRRK2 is highly expressed in the striatum, cortex and olfactory tubercle; however, little or no expression is found in the substantia nigra, where dopaminergic neurons preferentially degenerate in Parkinson's disease. These findings suggest that LRRK2 mRNA is expressed in dopamine-receptive areas rather than in the dopamine-synthesizing neurons. Consistent with a role LRRK2 in Parkinson's disease, dysfunction of leucine-rich repeat kinase 2 protein in dopamine-innervated areas may to lead to altered dopaminergic neurotransmission and degeneration of the nigro-striatal pathway. PMID:16504409

  3. Papain-Catalyzed Chemoenzymatic Synthesis of Telechelic Polypeptides Using Bis(Leucine Ethyl Ester) Initiator.

    PubMed

    Tsuchiya, Kousuke; Numata, Keiji

    2016-07-01

    In order to construct unique polypeptide architectures, a novel telechelic-type initiator with two leucine ethyl ester units is designed for chemoenzymatic polymerization. Glycine or alanine ethyl ester is chemoenzymatically polymerized using papain in the presence of the initiator, and the propagation occurs at each leucine ethyl ester unit to produce the telechelic polypeptide. The formation of the telechelic polypeptides is confirmed by (1) H NMR and MALDI-TOF mass spectroscopies. It is revealed by AFM observation that long nanofibrils are formed from the telechelic polyalanine, whereas a conventional linear polyalanine with a similar degree of polymerization shows granule-like structures. The telechelic polyglycine and polyalanine show the crystalline structures of Polyglycine II and antiparallel β-sheet, respectively. It is demonstrated that this method to synthesize telechelic-type polypeptides potentially opens up a pathway to construct novel hierarchical structures by self-assembly. PMID:26947148

  4. The radiolysis of tryptophan and leucine with P-32 beta-radiation

    NASA Technical Reports Server (NTRS)

    Blair, N. E.; Bonner, W. A.

    1980-01-01

    The paper extends earlier experiments on the radiolysis of DL-tryptophan using P-32 beta-radiation to longer reaction times, observing complete destruction of tryptophan by secondary, nonradiolytic processes. In addition DL-leucine is irradiated with P-32 beta-irradiation at -196 C, leading to radiolyses to the extents of about 20-30%, but observing no concomitant asymmetric bias. The complete absence of asymmetric bias in the present and earlier (Bonner et al., 1979) radiolyses of aqueous tryptophan at -25 C and the present radiolyses of water-free leucine at -196 C using P-32 beta-radiation and its accompanying bremsstrahlung leave it an open question whether or not the Vester-Ulbricht beta-decay/bremsstrahlung mechanism for the origin of optical activity is a viable one.

  5. Suppression of the HPA Axis During Cholestasis Can Be Attributed to Hypothalamic Bile Acid Signaling.

    PubMed

    McMillin, Matthew; Frampton, Gabriel; Quinn, Matthew; Divan, Ali; Grant, Stephanie; Patel, Nisha; Newell-Rogers, Karen; DeMorrow, Sharon

    2015-12-01

    Suppression of the hypothalamic-pituitary-adrenal (HPA) axis has been shown to occur during cholestatic liver injury. Furthermore, we have demonstrated that in a model of cholestasis, serum bile acids gain entry into the brain via a leaky blood brain barrier and that hypothalamic bile acid content is increased. Therefore, the aim of the current study was to determine the effects of bile acid signaling on the HPA axis. The data presented show that HPA axis suppression during cholestatic liver injury, specifically circulating corticosterone levels and hypothalamic corticotropin releasing hormone (CRH) expression, can be attenuated by administration of the bile acid sequestrant cholestyramine. Secondly, treatment of hypothalamic neurons with various bile acids suppressed CRH expression and secretion in vitro. However, in vivo HPA axis suppression was only evident after the central injection of the bile acids taurocholic acid or glycochenodeoxycholic acid but not the other bile acids studied. Furthermore, we demonstrate that taurocholic acid and glycochenodeoxycholic acid are exerting their effects on hypothalamic CRH expression after their uptake through the apical sodium-dependent bile acid transporter and subsequent activation of the glucocorticoid receptor. Taken together with previous studies, our data support the hypothesis that during cholestatic liver injury, bile acids gain entry into the brain, are transported into neurons through the apical sodium-dependent bile acid transporter and can activate the glucocorticoid receptor to suppress the HPA axis. These data also lend themselves to the broader hypothesis that bile acids may act as central modulators of hypothalamic peptides that may be altered during liver disease. PMID:26431088

  6. Impact of prolonged leucine supplementation on protein synthesis and lean growth in neonatal pigs.

    PubMed

    Columbus, Daniel A; Steinhoff-Wagner, Julia; Suryawan, Agus; Nguyen, Hanh V; Hernandez-Garcia, Adriana; Fiorotto, Marta L; Davis, Teresa A

    2015-09-15

    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. Neonatal pigs (n = 14-16/diet, 5 days old, 1.8 ± 0.3 kg) were fed by gastric catheter a whey-based milk replacement diet with either a high protein (HP) or restricted protein (RP) content or RP supplemented with leucine to the same level as in the HP diet (RPL). Pigs were fed 40 ml·kg body wt(-1)·meal(-1) every 4 h for 21 days. Feeding the HP diet resulted in greater total body weight and lean body mass compared with RP-fed pigs (P < 0.05). Masses of the longissimus dorsi muscle, heart, and kidneys were greater in the HP- than RP-fed pigs (P < 0.05). Body weight, lean body mass, and masses of the longissimus dorsi, heart, and kidneys in pigs fed the RPL diet were intermediate to RP- and HP-fed pigs. Protein synthesis and mTOR signaling were increased in all muscles with feeding (P < 0.05); leucine supplementation increased mTOR signaling and protein synthesis rate in the longissimus dorsi (P < 0.05). There was no effect of diet on indices of protein degradation signaling in any tissue (P > 0.05). Thus, when protein intake is chronically restricted, the capacity for leucine supplementation to enhance muscle protein accretion in neonatal pigs that are meal-fed milk protein-based diets is limited. PMID:26374843

  7. Fragment-based discovery of type I inhibitors of maternal embryonic leucine zipper kinase.

    PubMed

    Johnson, Christopher N; Berdini, Valerio; Beke, Lijs; Bonnet, Pascal; Brehmer, Dirk; Coyle, Joseph E; Day, Phillip J; Frederickson, Martyn; Freyne, Eddy J E; Gilissen, Ron A H J; Hamlett, Christopher C F; Howard, Steven; Meerpoel, Lieven; McMenamin, Rachel; Patel, Sahil; Rees, David C; Sharff, Andrew; Sommen, François; Wu, Tongfei; Linders, Joannes T M

    2015-01-01

    Fragment-based drug design was successfully applied to maternal embryonic leucine zipper kinase (MELK). A low affinity (160 μM) fragment hit was identified, which bound to the hinge region with an atypical binding mode, and this was optimized using structure-based design into a low-nanomolar and cell-penetrant inhibitor, with a good selectivity profile, suitable for use as a chemical probe for elucidation of MELK biology. PMID:25589925

  8. Regulation of transaminase C synthesis in Escherichia coli: conditional leucine auxotrophy.

    PubMed

    McGilvray, D; Umbarger, H E

    1974-11-01

    The regulation of synthesis of the valine-alanine-alpha-aminobutyrate transaminase (transaminase C) was studied in Escherichia coli mutants lacking the branched-chain amino acid transaminase (transaminase B). An investigation was made of two strains, CU2 and CU2002, each carrying the same transaminase B lesion but exhibiting different growth responses on a medium supplemented with branched-chain amino acids. Both had the absolute isoleucine requirement characteristic of ilvE auxotrophs, but growth of strain CU2 was stimulated by valine, whereas that of strain CU2002 was markedly inhibited by valine. Strain CU2002 behaved like a conditional leucine auxotroph in that the inhibition by valine was reversed by leucine. Results of enzymatic studies showed that synthesis of transaminase C was repressed by valine in strain CU2002 but not in strain CU2. Inhibition by valine in strain CU2002 appears to be the combined effect of repression on transaminase C synthesis and valine-dependent feedback inhibition of alpha-acetohydroxy acid synthase activity, causing alpha-ketoisovalerate (and hence leucine) limitation. The ilvE markers of strains CU2 and CU2002 were each transferred by transduction to a wild-type genetical background. All ilvE recombinants from both crosses resembled strain CU2002 and were inhibited by valine in the presence of isoleucine. Thus, strain CU2 carries an additional lesion that allows it to grow on a medium containing isoleucine plus valine. It is concluded that conditional leucine auxotrophy is characteristic of mutants carrying an ilvE lesion alone. PMID:4616947

  9. Lysine and Leucine Deficiencies Affect Myocytes Development and IGF Signaling in Gilthead Sea Bream (Sparus aurata)

    PubMed Central

    Azizi, Sheida; Nematollahi, Mohammad Ali; Mojazi Amiri, Bagher; Vélez, Emilio J.; Lutfi, Esmail; Navarro, Isabel; Capilla, Encarnación; Gutiérrez, Joaquim

    2016-01-01

    Optimizing aquaculture production requires better knowledge of growth regulation and improvement in diet formulation. A great effort has been made to replace fish meal for plant protein sources in aquafeeds, making necessary the supplementation of such diets with crystalline amino acids (AA) to cover the nutritional requirements of each species. Lysine and Leucine are limiting essential AA in fish, and it has been demonstrated that supplementation with them improves growth in different species. However, the specific effects of AA deficiencies in myogenesis are completely unknown and have only been studied at the level of hepatic metabolism. It is well-known that the TOR pathway integrates the nutritional and hormonal signals to regulate protein synthesis and cell proliferation, to finally control muscle growth, a process also coordinated by the expression of myogenic regulatory factors (MRFs). This study aimed to provide new information on the impact of Lysine and Leucine deficiencies in gilthead sea bream cultured myocytes examining their development and the response of insulin-like growth factors (IGFs), MRFs, as well as key molecules involved in muscle growth regulation like TOR. Leucine deficiency did not cause significant differences in most of the molecules analyzed, whereas Lysine deficiency appeared crucial in IGFs regulation, decreasing significantly IGF-I, IGF-II and IGF-IRb mRNA levels. This treatment also down-regulated the gene expression of different MRFs, including Myf5, Myogenin and MyoD2. These changes were also corroborated by a significant decrease in proliferation and differentiation markers in the Lysine-deficient treatment. Moreover, both Lysine and Leucine limitation induced a significant down-regulation in FOXO3 gene expression, which deserves further investigation. We believe that these results will be relevant for the production of a species as appreciated for human consumption as it is gilthead sea bream and demonstrates the importance of

  10. Relations among arginine, citrulline, ornithine, and leucine kinetics in adult burn patients.

    PubMed

    Yu, Y M; Ryan, C M; Burke, J F; Tompkins, R G; Young, V R

    1995-11-01

    Plasma fluxes of arginine, citrulline, and leucine, and the rate of conversion of labeled citrulline to arginine (Qcit-->arg) were determined in nine severely burned patients (mean: 56% body surface burn area, mean 10 d postinjury) while they received total parenteral nutrition (TPN) including an L-amino acid mixture that supplied a generous amount of nitrogen (mean: 0.39 +/- 0.02 g.kg-1.d-1). Plasma fluxes were also studied in these patients during a basal state (low-dose intravenous glucose) by using a primed, 4-h constant intravenous tracer-infusion protocol. Stable-nuclide labeled tracers were L-[15N-15N-guanidino,5,5,2H2]arginine; L-[13C-ureido]citrulline; L-[1-13C]leucine; and NaH13CO3 (prime only), with blood and expired air samples drawn at intervals to determine isotopic abundance of arginine, citrulline, ornithine, and alpha-ketoisocaproate (KIC; for leucine) in plasma and 13CO2 in breath. Leucine kinetics (flux and disappearance into protein synthesis) confirmed the anticipated higher protein turnover in these burn patients compared with healthy control subjects. The plasma arginine fluxes were correspondingly higher in burn patients than in healthy control subjects. However, the citrulline flux and rate of conversion of citrulline to arginine were not higher than values obtained in our laboratories in healthy adult subjects. We hypothesize that the higher rates of arginine loss from the body after burn injury would need to be balanced by an appropriate exogenous intake of preformed arginine to maintain protein homeostasis and promote recovery from this catabolic condition. PMID:7572742

  11. Structural and functional evolution of isopropylmalate dehydrogenases in the leucine and glucosinolate pathways of Arabidopsis thaliana

    SciTech Connect

    He, Yan; Galant, Ashley; Pang, Qiuying; Strul, Johanna M.; Balogun, Sherifat F.; Jez, Joseph M.; Chen, Sixue

    2012-10-24

    The methionine chain-elongation pathway is required for aliphatic glucosinolate biosynthesis in plants and evolved from leucine biosynthesis. In Arabidopsis thaliana, three 3-isopropylmalate dehydrogenases (AtIPMDHs) play key roles in methionine chain-elongation for the synthesis of aliphatic glucosinolates (e.g. AtIPMDH1) and leucine (e.g. AtIPMDH2 and AtIPMDH3). Here we elucidate the molecular basis underlying the metabolic specialization of these enzymes. The 2.25 {angstrom} resolution crystal structure of AtIPMDH2 was solved to provide the first detailed molecular architecture of a plant IPMDH. Modeling of 3-isopropylmalate binding in the AtIPMDH2 active site and sequence comparisons of prokaryotic and eukaryotic IPMDH suggest that substitution of one active site residue may lead to altered substrate specificity and metabolic function. Site-directed mutagenesis of Phe-137 to a leucine in AtIPMDH1 (AtIPMDH1-F137L) reduced activity toward 3-(2'-methylthio)ethylmalate by 200-fold, but enhanced catalytic efficiency with 3-isopropylmalate to levels observed with AtIPMDH2 and AtIPMDH3. Conversely, the AtIPMDH2-L134F and AtIPMDH3-L133F mutants enhanced catalytic efficiency with 3-(2'-methylthio)ethylmalate {approx}100-fold and reduced activity for 3-isopropylmalate. Furthermore, the altered in vivo glucosinolate profile of an Arabidopsis ipmdh1 T-DNA knock-out mutant could be restored to wild-type levels by constructs expressing AtIPMDH1, AtIPMDH2-L134F, or AtIPMDH3-L133F, but not by AtIPMDH1-F137L. These results indicate that a single amino acid substitution results in functional divergence of IPMDH in planta to affect substrate specificity and contributes to the evolution of specialized glucosinolate biosynthesis from the ancestral leucine pathway.

  12. Site reactivity in the free radicals induced damage to leucine residues: a theoretical study.

    PubMed

    Medina, M E; Galano, A; Alvarez-Idaboy, J R

    2015-02-21

    Several recent computational studies have tried to explain the observed selectivity in radical damage to proteins. In this work we use Density Functional Theory and Transition State Theory including tunnelling corrections, reaction path degeneracy, the effect of diffusion, and the role of free radicals to get further insights into this important topic. The reaction between a leucine derivative and free radicals of biological significance, in aqueous and lipid media, has been investigated. Both thermochemical and kinetic analyses, in both hydrophilic and hydrophobic environments, have been carried out. DPPH, ˙OOH, ˙OOCH3, ˙OOCH2Cl, ˙OOCHCl2 and ˙OOCHCH2 radicals do not react with the target molecule. The reactions are proposed to be kinetically controlled. The leucine gamma site was the most reactive for the reactions with ˙N3, ˙OOCCl3, ˙OCH3, ˙OCH2Cl, and ˙OCHCl2 radicals, with rate constants equal to 1.97 × 10(5), 3.24 × 10(4), 6.68 × 10(5), 5.98 × 10(6) and 8.87 × 10(8) M(-1) s(-1), respectively, in aqueous solution. The ˙Cl, ˙OH and ˙OCCl3 radicals react with leucine at the beta, gamma, and delta positions at rates close to the diffusion limit with the alpha position which is the slowest path and the most thermodynamically favored. The presented results confirm that the Bell-Evans-Polanyi principle does not apply for the reactions between amino acid residues and free radicals. Regarding the influence of the environment on the reactivity of the studied series of free radicals towards leucine residues, it is concluded that hydrophilic media slightly lower the reactivity of the studied radicals, compared to hydrophobic ones, albeit the trends in reactivity are very similar. PMID:25592549

  13. Fragment-Based Discovery of Type I Inhibitors of Maternal Embryonic Leucine Zipper Kinase

    PubMed Central

    2014-01-01

    Fragment-based drug design was successfully applied to maternal embryonic leucine zipper kinase (MELK). A low affinity (160 μM) fragment hit was identified, which bound to the hinge region with an atypical binding mode, and this was optimized using structure-based design into a low-nanomolar and cell-penetrant inhibitor, with a good selectivity profile, suitable for use as a chemical probe for elucidation of MELK biology. PMID:25589925

  14. Ontogeny of gene expression in the hypothalamic-pitutitary axis and luteinizing hormone secretion during pubertal development in the gilt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The occurrence of puberty in the female is due to the interplay of central and peripheral mechanisms in which the hypothalamic-pituitary-ovarian axis regulates growth, gonadal function, as well as, adipocyte hormone secretion. Hypothalamic GnRH mRNA expression did not change. Concomitant with the ag...

  15. Leucine incorporation by aerobic anoxygenic phototrophic bacteria in the Delaware estuary

    PubMed Central

    Stegman, Monica R; Cottrell, Matthew T; Kirchman, David L

    2014-01-01

    Aerobic anoxygenic phototrophic (AAP) bacteria are well known to be abundant in estuaries, coastal regions and in the open ocean, but little is known about their activity in any aquatic ecosystem. To explore the activity of AAP bacteria in the Delaware estuary and coastal waters, single-cell 3H-leucine incorporation by these bacteria was examined with a new approach that combines infrared epifluorescence microscopy and microautoradiography. The approach was used on samples from the Delaware coast from August through December and on transects through the Delaware estuary in August and November 2011. The percent of active AAP bacteria was up to twofold higher than the percentage of active cells in the rest of the bacterial community in the estuary. Likewise, the silver grain area around active AAP bacteria in microautoradiography preparations was larger than the area around cells in the rest of the bacterial community, indicating higher rates of leucine consumption by AAP bacteria. The cell size of AAP bacteria was 50% bigger than the size of other bacteria, about the same difference on average as measured for activity. The abundance of AAP bacteria was negatively correlated and their activity positively correlated with light availability in the water column, although light did not affect 3H-leucine incorporation in light–dark experiments. Our results suggest that AAP bacteria are bigger and more active than other bacteria, and likely contribute more to organic carbon fluxes than indicated by their abundance. PMID:24824666

  16. Phase Shift of the Circadian Rhythm of Lemna Caused by Pulses of a Leucine Analog, Trifluoroleucine

    PubMed Central

    Kondo, Takao

    1988-01-01

    Pulses of a fluorinated analog of leucine, 5′,5′,5′-trifluoroleucine, reset the phase of the circadian rhythm of K+ uptake in Lemna gibba G3 under continuous light conditions. The trifluoroleucine pulse caused the largest delay phase-shifts during the early subjective phase but it caused only small phase advances. The action of trifluoroleucine was investigated and the following results were obtained. (a) The uptake of trifluoroleucine was essentially the same at all circadian phases, even though phase shifting was dramatically different at different phases. At effective phases, the magnitude of phase shifting was well correlated with the amount of trifluoroleucine taken up by the duckweed. (b) The trifluoroleucine pulse lowered the endogenous content of valine and leucine but these decreases did not correlate with phase shifting. (c) Protein synthesis was not affected by trifluoroleucine pulses which caused large phase shifts. (d) Pulses of 4-azaleucine, a different structural analog of leucine, also caused phase shifting. However, neither the direction nor the effective times of phase shifting were similar to those of trifluoroleucine. Taken together, these results negate the proposition that trifluoroleucine and azaleucine caused phase shift by disturbing amino acid metabolism and/or inhibiting protein synthesis, but they suggest instead that these analogs are incorporated into some protein(s) which are necessary for normal clock operation. PMID:16666410

  17. Leucine metabolism regulates TRI6 expression and affects deoxynivalenol production and virulence in Fusarium graminearum.

    PubMed

    Subramaniam, Rajagopal; Narayanan, Swara; Walkowiak, Sean; Wang, Li; Joshi, Manisha; Rocheleau, Hélène; Ouellet, Thérèse; Harris, Linda J

    2015-11-01

    TRI6 is a positive regulator of the trichothecene gene cluster and the production of trichothecene mycotoxins [deoxynivalenol (DON)] and acetylated forms such as 15-Acetyl-DON) in the cereal pathogen Fusarium graminearum. As a global transcriptional regulator, TRI6 expression is modulated by nitrogen-limiting conditions, sources of nitrogen and carbon, pH and light. However, the mechanism by which these diverse environmental factors affect TRI6 expression remains underexplored. In our effort to understand how nutrients affect TRI6 regulation, comparative digital expression profiling was performed with a wild-type F. graminearum and a Δtri6 mutant strain, grown in nutrient-rich conditions. Analysis showed that TRI6 negatively regulates genes of the branched-chain amino acid (BCAA) metabolic pathway. Feeding studies with deletion mutants of MCC, encoding methylcrotonyl-CoA-carboxylase, one of the key enzymes of leucine metabolism, showed that addition of leucine specifically down-regulated TRI6 expression and reduced 15-ADON accumulation. Constitutive expression of TRI6 in the Δmcc mutant strain restored 15-ADON production. A combination of cellophane breach assays and pathogenicity experiments on wheat demonstrated that disrupting the leucine metabolic pathway significantly reduced disease. These findings suggest a complex interaction between one of the primary metabolic pathways with a global regulator of mycotoxin biosynthesis and virulence in F. graminearum. PMID:26248604

  18. Conversion of L-leucine to isovaleric acid by Propionibacterium freudenreichii TL 34 and ITGP23.

    PubMed

    Thierry, Anne; Maillard, Marie-Bernadette; Yvon, Mireille

    2002-02-01

    Several branched-chain volatile compounds are involved in the flavor of Swiss cheese. These compounds are probably produced by enzymatic conversion of branched-chain amino acids, but the flora and the pathways involved remain hypothetical. Our aim was to determine the ability of Propionibacterium freudenreichii, which is one of the main components of the secondary flora of Swiss cheese, to produce flavor compounds during leucine catabolism. Cell extracts and resting cells of two strains were incubated in the presence of L-leucine, alpha-ketoglutaric acid, and cofactors, and the metabolites produced were determined by high-performance liquid chromatography and gas chromatography. The first step of leucine catabolism was a transamination that produced alpha-ketoisocaproic acid, which was enzymatically converted to isovaleric acid. Both reactions were faster at pH 8.0 than at acidic pHs. Cell extracts catalyzed only the transamination step under our experimental conditions. Small amounts of 3-methylbutanol were also produced by resting cells, but neither 3-methylbutanal noralpha-hydroxyisocaproic acid was detected. L-Isoleucine and L-valine were also converted to the corresponding acids and alcohols. Isovaleric acid was produced by both strains during growth in a complex medium, even under conditions simulating Swiss cheese conditions (2.1% NaCl, pH 5.4, 24 degrees C). Our results show that P. frendenreichii could play a significant role in the formation of isovaleric acid during ripening. PMID:11823198

  19. Specific regulatory interconnection between the leucine and histidine pathways of Neurospora crassa.

    PubMed Central

    Kidd, G L; Gross, S R

    1984-01-01

    Leucine auxotrophs of Neurospora fall into two discrete categories with respect to sensitivity to the herbicide, 3-amino-1,2,4-triazole. The pattern of resistance corresponds exactly to the ability to produce the leucine pathway control elements, alpha-isopropylmalate and the leu-3 product. An analysis of the regulatory response of the production of enzymes of histidine biosynthesis to alpha-isopropylmalate implicates the control elements of the leucine pathway as important components of the mechanism governing the production of the target enzyme of aminotriazole inhibition, imidazoleglycerol-phosphate dehydratase (EC 4.2.1.19). The evidence suggests that the regulatory interconnection between the two pathways is direct and is independent of other general integrating regulatory mechanisms which appear to be operative in both pathways. A general method for isolating leu-1 and leu-2, as well as other regulatory mutants, is described, which takes advantage of the specificity of the resistance to the inhibitor. Use of analogous systems is prescribed for the analysis of other regulatory interconnections which, like this one, might not be anticipated directly from structural or biosynthetic considerations. PMID:6325383

  20. Estimation of whole body protein synthesis from oxidation of infused [1-14C]leucine.

    PubMed

    Yagi, M; Walser, M

    1990-01-01

    In rats infused with NaH14CO3, 14CO2 exhalation approached an asymptotic rate equal to 96.0 +/- 1.3 (SD) % of the infusion rate of 14C in a monoexponential manner with a half-time of 20 min. In rats infused with [1-14C]leucine, 14CO2 exhalation (/0.96) approached an asymptotic value, (1-F), of 16-25% of 14C infusion rate (mean 20.4%) in a monoexponential manner with a half-time of approximately 31 min. Whole body protein synthesis (S) was calculated from 1-F and urea N plus ammonia N excretion (C) as S = CF/(1-F). S was a uniform function of body weight in these rats, in six additional rats in which S was measured 6 h after single intravenous injection of [1-14C]leucine and also in previously reported rats given single injections. The relationship was S (mg.100 g-1.h-1) = 11-0.143 body wt (g) +/- 8.3. In six of these rats, S was also estimated from the plateau specific activity of plasma leucine or plasma 2-ketoisocaproate (KIC); the former estimate of S was significantly lower (by an average of 17%), but S was the same when specific activity of KIC was employed. These results support the validity of the expired 14CO2 technique for measuring S. PMID:2154116

  1. Trp387 and the putative leucine zippers of PGH synthases-1 and -2.

    PubMed

    Hsi, L C; Tsai, A L; Kulmacz, R J; English, D G; Siefker, A O; Otto, J C; Smith, W L

    1993-01-01

    The active site sequence 385-YHWH-388 of ovine prostaglandin endoperoxide synthase-1 (PGHS-1) has residues critical for cyclooxygenase and peroxidase catalysis. Tyr385 is essential for cyclooxygenase activity, His386, for peroxidase activity, and His388, for both activities. To determine the importance of Trp387, we used site-directed mutagenesis to replace Trp387 of PGHS-1 with arginine, phenylalanine, and serine. W387R and W387S lacked significant activity. W387F retained both cyclooxygenase and peroxidase activities. Thus, we conclude that Trp387 is not essential for catalysis by PGHS-1. Purified PGHS-1 is a homodimer. There are two putative leucine zipper regions in ovine PGHS-1 involving residues 345-366 and 487-508. We tested for a role of these leucine zippers as determinants of dimer formation. Helix-breaking proline mutations were introduced at Leu359 or Leu501. Neither of these residues proved to be essential for peroxidase activity; but, mutations at each residue greatly reduced or eliminated cyclooxygenase activity. Both mutant proteins chromatographed as dimers on Sephacryl G-200. Thus, neither of these putative leucine zipper regions alone is responsible for PGHS-1 dimer formation. PMID:8357979

  2. The minimal model of the hypothalamic-pituitary-adrenal axis.

    PubMed

    Vinther, Frank; Andersen, Morten; Ottesen, Johnny T

    2011-10-01

    This paper concerns ODE modeling of the hypothalamic-pituitary- adrenal axis (HPA axis) using an analytical and numerical approach, combined with biological knowledge regarding physiological mechanisms and parameters. The three hormones, CRH, ACTH, and cortisol, which interact in the HPA axis are modeled as a system of three coupled, nonlinear differential equations. Experimental data shows the circadian as well as the ultradian rhythm. This paper focuses on the ultradian rhythm. The ultradian rhythm can mathematically be explained by oscillating solutions. Oscillating solutions to an ODE emerges from an unstable fixed point with complex eigenvalues with a positive real parts and a non-zero imaginary parts. The first part of the paper describes the general considerations to be obeyed for a mathematical model of the HPA axis. In this paper we only include the most widely accepted mechanisms that influence the dynamics of the HPA axis, i.e. a negative feedback from cortisol on CRH and ACTH. Therefore we term our model the minimal model. The minimal model, encompasses a wide class of different realizations, obeying only a few physiologically reasonable demands. The results include the existence of a trapping region guaranteeing that concentrations do not become negative or tend to infinity. Furthermore, this treatment guarantees the existence of a unique fixed point. A change in local stability of the fixed point, from stable to unstable, implies a Hopf bifurcation; thereby, oscillating solutions may emerge from the model. Sufficient criteria for local stability of the fixed point, and an easily applicable sufficient criteria guaranteeing global stability of the fixed point, is formulated. If the latter is fulfilled, ultradian rhythm is an impossible outcome of the minimal model and all realizations thereof. The second part of the paper concerns a specific realization of the minimal model in which feedback functions are built explicitly using receptor dynamics. Using

  3. The obesity‐associated gene Negr1 regulates aspects of energy balance in rat hypothalamic areas

    PubMed Central

    Boender, Arjen J.; van Gestel, Margriet A.; Garner, Keith M.; Luijendijk, Mieneke C. M.; Adan, Roger A. H.

    2014-01-01

    Abstract Neural growth regulator 1 (Negr1) is among the first common variants that have been associated with the regulation of body mass index. Using AAV technology directed to manipulate Negr1 expression in vivo, we find that decreased expression of Negr1 in periventricular hypothalamic areas leads to increases in body weight, presumably via increased food intake. Moreover, we observed that both increased and decreased levels of Negr1 lead to reduced locomotor activity and body temperature. In sum, our results provide further support for a role of hypothalamic expressed Negr1 in the regulation of energy balance. PMID:25077509

  4. Involvement of neurogenesis in the hypothalamic area in establishing long-term heat acclimation in rats

    PubMed Central

    Shido, Osamu; Matsuzaki, Kentaro

    2015-01-01

    This review summarizes earlier studies of long-term heat acclimation (LHA) in rats. Since thermoregulatory changes of LHA are stable and sustained, persisting functional and morphological changes are expected to occur in the thermoregulatory centers. Heat exposure increases the number of newborn cells in the ependymal layer of the third ventricle. With time, these newborn cells migrate into the hypothalamic parenchyma and differentiate to immature or mature neurons, some of which integrate into hypothalamic neuralne tworks. The generation of new functional neurons in the hypothalamus may be an important mechanism of LHA.

  5. The functional activity of hypothalamic signaling systems in rats with neonatal diabetes mellitus treated with metformin.

    PubMed

    Derkach, K V; Sukhov, I B; Kuznetsova, L A; Buzanakov, D M; Shpakov, A O

    2016-03-01

    The effect of the two-month metformin treatment (200 mg/kg/day) of rats with the neonatal model of type 2 diabetes mellitus on the functional activity of hypothalamic signaling systems was studied. It was shown that metformin treatment restored the sensitivity of hypothalamic adenylyl cyclase signaling system to agonists of the type 4 melanocortin receptor and the type 2 dopamine receptor but did not influence significantly the functions of the insulin signaling system. These data suggest new targets and mechanisms of metformin action in the CNS, which may mediate its restoring effect on energy homeostasis impaired in diabetic pathology. PMID:27193707

  6. Increased concentration of. cap alpha. - and. gamma. -endorphin in post mortem hypothalamic tissue of schizophrenic patients

    SciTech Connect

    Wiegant, V.M.; Verhoef, C.J.; Burbach, J.P.H.; de Wied, D.

    1988-01-01

    The concentrations of ..cap alpha..-, ..beta..- and ..gamma..-endorphin were determined by radioimmunoassay in HPLC fractionated extracts of post mortem hypothalamic tissue obtained from schizophrenic patients and controls. The hypothalamic concentration of ..cap alpha..- and ..gamma..-endorphin was significantly higher in patients than in controls. No difference was found in the concentration of ..beta..-endorphin, the putative precursor of ..cap alpha..- and ..gamma..-endorphins. These results suggest a deviant metabolism of ..beta..-endorphin in the brain of schizophrenic patients. Whether this phenomenon is related to the psychopathology, or is a consequence of ante mortem farmacotherapy, remains to be established.

  7. HYPOTHALAMIC DIGOXIN AND SCHIZOPHRENIA - A MODEL FOR CONSCIOUS AND SUBLIMINAL PERCEPTION AND ITS DYSFUNCTION IN SCHIZOPHRENIA

    PubMed Central

    Kurup, Ravikumar A.; Augustine, Jyothi; Kurup, P.A.

    1999-01-01

    In view of reports of an upregulated cation pump in genetically related Bipolar Affective Disorders the role of hypothalamic digoxin, an endogenous regulator of the cation pump was studied with special reference to its role as a modulator of glycoprotein synthesis. The study demonstrated elevated serum digoxin levels, elevated HMG CoA reductase activity suggesting increased digoxin synthesis, reduced sodium-potassium ATPase activity and altered sugar residues of serum glycoprotein in schizophrenia. A hypothalamic digoxin mediated model for conscious and subliminal perception is proposed and the significance of its dysfunction due to abnormal glycoprotein induced synaptic connectivity defects in schizophrenia is discussed. PMID:21455390

  8. Hypothalamic Extraventricular Neurocytoma (EVN) in a Pediatric Patient: A Case of EVN Treated with Subtotal Removal Followed by Adjuvant Radiotherapy

    PubMed Central

    Cho, Minjae; Joo, Jin-Deok; Kim, Baek-hui; Choe, Gheeyoung

    2016-01-01

    Extra ventricular neurocytoma (EVN) is a rare brain tumor with histologic features similar with a central neurocytoma, but located outside of the ventricular system. In this study, we present an unusual case of hypothalamic EVN in a 14-year-old patient. The patient underwent subtotal removal and had tumor relapse. The patient was then treated using intensity modulated radiation therapy, and the tumor remained stable for 24 months. This case report may be important in that this is the first pediatric case of EVN located in the hypothalamic region. EVN has similar radiologic features with pilocytic astrocytomas and therefore a hypothalamic EVN may be misdiagnosed as a hypothalamic glioma. Also, the pathologic-radiologic-clinical correlation of EVN located in the hypothalamic area may be different from that of EVNs originating from other usual sites. PMID:27195261

  9. Impact of Leucine Supplementation on Exercise Training Induced Anti-Cardiac Remodeling Effect in Heart Failure Mice

    PubMed Central

    de Moraes, Wilson Max Almeida Monteiro; Melara, Thaís Plasti; de Souza, Pamella Ramona Moraes; de Salvi Guimarães, Fabiana; Bozi, Luiz Henrique Marchesi; Brum, Patricia Chakur; Medeiros, Alessandra

    2015-01-01

    Leucine supplementation potentiates the effects of aerobic exercise training (AET) on skeletal muscle; however, its potential effects associated with AET on cardiac muscle have not been clarified yet. We tested whether leucine supplementation would potentiate the anti-cardiac remodeling effect of AET in a genetic model of sympathetic hyperactivity-induced heart failure in mice (α2A/α2CARKO). Mice were assigned to five groups: wild type mice treated with placebo and sedentary (WT, n = 11), α2A/α2CARKO treated with placebo and sedentary (KO, n = 9), α2A/α2CARKO treated with leucine and sedentary (KOL, n = 11), α2A/α2CARKO treated with placebo and AET (KOT, n = 12) or α2A/α2CARKO treated with leucine and AET (KOLT, n = 12). AET consisted of four weeks on a treadmill with 60 min sessions (six days/week, 60% of maximal speed) and administration by gavage of leucine (1.35 g/kg/day) or placebo (distilled water). The AET significantly improved exercise capacity, fractional shortening and re-established cardiomyocytes’ diameter and collagen fraction in KOT. Additionally, AET significantly prevented the proteasome hyperactivity, increased misfolded proteins and HSP27 expression. Isolated leucine supplementation displayed no effect on cardiac function and structure (KOL), however, when associated with AET (KOLT), it increased exercise tolerance to a higher degree than isolated AET (KOT) despite no additional effects on AET induced anti-cardiac remodeling. Our results provide evidence for the modest impact of leucine supplementation on cardiac structure and function in exercised heart failure mice. Leucine supplementation potentiated AET effects on exercise tolerance, which might be related to its recognized impact on skeletal muscle. PMID:25988767

  10. Lean body mass change over 6 years is associated with dietary leucine intake in an older Danish population.

    PubMed

    McDonald, Cameron Keith; Ankarfeldt, Mikkel Z; Capra, Sandra; Bauer, Judy; Raymond, Kyle; Heitmann, Berit Lilienthal

    2016-05-01

    Higher protein intake, and particularly higher leucine intake, is associated with attenuated loss of lean body mass (LBM) over time in older individuals. Dietary leucine is thought to be a key mediator of anabolism. This study aimed to assess this relationship over 6 years among younger and older adult Danes. Dietary leucine intake was assessed at baseline and after 6 years in men and women, aged 35-65 years, participating in the Danish cohort of the WHO-MONICA (Multinational MONItoring of trends and determinants in CArdiovascular disease) study (n 368). Changes in LBM over the 6 years were measured by bioelectrical impedance using equations developed for this Danish population. The association between leucine and LBM changes was examined using multivariate linear regression and ANCOVA analyses adjusted for potential confounders. After adjustment for baseline LBM, sex, age, energy intake and physical activity, leucine intake was associated with LBM change in those older than 65 years (n 79), with no effect seen in those younger than 65 years. Older participants in the highest quartile of leucine intake (7·1 g/d) experienced LBM maintenance, whereas lower intakes were associated with LBM loss over 6 years (for trend: β=0·434, P=0·03). Sensitivity analysis indicated no effect modification of sex or the presence of CVD. Greater leucine intake in conjunction with adequate total protein intake was associated with long-term LBM retention in a healthy older Danish population. This study corroborates findings from laboratory investigations in relation to protein and leucine intakes and LBM change. A more diverse and larger sample is needed for confirmation of these results. PMID:26979049

  11. Monitoring stepwise proteolytic degradation of peptides by supramolecular domino tandem assays and mass spectrometry for trypsin and leucine aminopeptidase.

    PubMed

    Ghale, Garima; Kuhnert, Nikolai; Nau, Werner M

    2012-03-01

    A label-free optical detection method has been designed that allows direct monitoring of enzymatic peptide digestion in vitro. The method is based on the addition of a reporter pair, composed of the macrocyclic host cucurbit[7]uril (CB7) and the fluorescent dye acridine orange (AO), to detect the proteolytic degradation of peptides. The enzymatic activity of trypsin and leucine aminopeptidase (LAP) was investigated using H-LSRFSWGA-OH as a substrate. The substrate as well as the intermediary and final products (i.e., H-FSWGA-OH and phenylalanine) formed during its enzymatic hydrolysis differ in their binding affinity to the receptor CB7, which results in varying degrees of dye displacement and, therefore, different fluorescence intensities. CB7 showed a relatively weak binding constant of K approximately 10(4) M(-1) with the substrate, a relatively strong binding constant of K > or = 10(6) M(-1) with H-FSWGA-OH (which is a final product formed by trypsin digestion and the intermediary product formed during the enzymatic activity of LAP), and a moderate binding constant of K < or = 10(5) M(-1) with phenylalanine. Owing to this differential binding affinity of CB7 with the substrate and the corresponding products, the digestion of a peptide by trypsin was followed as a decrease in fluorescence signal, while the complete degradation of the peptide by LAP was monitored as a decrease and a subsequent increase in fluorescence signal. The k(cat)/K(M) value for trypsin (2.0 x 10(7) min(-1) M(-1)) was derived from the change in fluorescence signal with time. Additionally, the complete degradation of the peptide by LAP was also followed by mass spectrometry. The use of a supramolecular sensing ensemble (macrocyclic host and dye) as a fluorescent reporter pair gives this method the flexibility to adapt for monitoring the stepwise degradation of different biologically relevant peptides by other proteases. PMID:22545408

  12. Pregnancy induces resistance to the anorectic effect of hypothalamic malonyl-CoA and the thermogenic effect of hypothalamic AMPK inhibition in female rats.

    PubMed

    Martínez de Morentin, Pablo B; Lage, Ricardo; González-García, Ismael; Ruíz-Pino, Francisco; Martins, Luís; Fernández-Mallo, Diana; Gallego, Rosalía; Fernø, Johan; Señarís, Rosa; Saha, Asish K; Tovar, Sulay; Diéguez, Carlos; Nogueiras, Rubén; Tena-Sempere, Manuel; López, Miguel

    2015-03-01

    During gestation, hyperphagia is necessary to cope with the metabolic demands of embryonic development. There were three main aims of this study: Firstly, to investigate the effect of pregnancy on hypothalamic fatty acid metabolism, a key pathway for the regulation of energy balance; secondly, to study whether pregnancy induces resistance to the anorectic effect of fatty acid synthase (FAS) inhibition and accumulation of malonyl-coenzyme A (CoA) in the hypothalamus; and, thirdly, to study whether changes in hypothalamic AMPK signaling are associated with brown adipose tissue (BAT) thermogenesis during pregnancy. Our data suggest that in pregnant rats, the hypothalamic fatty acid pathway shows an overall state that should lead to anorexia and elevated BAT thermogenesis: decreased activities of AMP-activated protein kinase (AMPK), FAS, and carnitine palmitoyltransferase 1, coupled with increased acetyl-CoA carboxylase function with subsequent elevation of malonyl-CoA levels. This profile seems dependent of estradiol levels but not prolactin or progesterone. Despite the apparent anorexic and thermogenic signaling in the hypothalamus, pregnant rats remain hyperphagic and display reduced temperature and BAT function. Actually, pregnant rats develop resistance to the anorectic effects of central FAS inhibition, which is associated with a reduction of proopiomelanocortin (POMC) expression and its transcription factors phospho-signal transducer and activator of transcription 3, and phospho-forkhead box O1. This evidence demonstrates that pregnancy induces a state of resistance to the anorectic and thermogenic actions of hypothalamic cellular signals of energy surplus, which, in parallel to the already known refractoriness to leptin effects, likely contributes to gestational hyperphagia and adiposity. PMID:25535827

  13. Pregnancy Induces Resistance to the Anorectic Effect of Hypothalamic Malonyl-CoA and the Thermogenic Effect of Hypothalamic AMPK Inhibition in Female Rats

    PubMed Central

    Martínez de Morentin, Pablo B.; Lage, Ricardo; González-García, Ismael; Ruíz-Pino, Francisco; Martins, Luís; Fernández-Mallo, Diana; Gallego, Rosalía; Fernø, Johan; Señarís, Rosa; Saha, Asish K.; Tovar, Sulay; Diéguez, Carlos; Nogueiras, Rubén; Tena-Sempere, Manuel

    2015-01-01

    During gestation, hyperphagia is necessary to cope with the metabolic demands of embryonic development. There were three main aims of this study: Firstly, to investigate the effect of pregnancy on hypothalamic fatty acid metabolism, a key pathway for the regulation of energy balance; secondly, to study whether pregnancy induces resistance to the anorectic effect of fatty acid synthase (FAS) inhibition and accumulation of malonyl-coenzyme A (CoA) in the hypothalamus; and, thirdly, to study whether changes in hypothalamic AMPK signaling are associated with brown adipose tissue (BAT) thermogenesis during pregnancy. Our data suggest that in pregnant rats, the hypothalamic fatty acid pathway shows an overall state that should lead to anorexia and elevated BAT thermogenesis: decreased activities of AMP-activated protein kinase (AMPK), FAS, and carnitine palmitoyltransferase 1, coupled with increased acetyl-CoA carboxylase function with subsequent elevation of malonyl-CoA levels. This profile seems dependent of estradiol levels but not prolactin or progesterone. Despite the apparent anorexic and thermogenic signaling in the hypothalamus, pregnant rats remain hyperphagic and display reduced temperature and BAT function. Actually, pregnant rats develop resistance to the anorectic effects of central FAS inhibition, which is associated with a reduction of proopiomelanocortin (POMC) expression and its transcription factors phospho-signal transducer and activator of transcription 3, and phospho-forkhead box O1. This evidence demonstrates that pregnancy induces a state of resistance to the anorectic and thermogenic actions of hypothalamic cellular signals of energy surplus, which, in parallel to the already known refractoriness to leptin effects, likely contributes to gestational hyperphagia and adiposity. PMID:25535827

  14. Biosynthesis of 4-methyleneglutamic acid by peanut seedlings: Evidence for the involvement of a distinct source of leucine

    SciTech Connect

    Winter, H.C.; Dekker, E.E. )

    1989-04-01

    Germinating peanut seeds accumulate 4-methyleneglutamic acid its {gamma}-amide(MeGlx), as well as 4-methylglutamic acid(MGlu) for which leucine has been implicated as a precursor. When we incubated detached peanut cotyledons with {sup 14}C-leucine for 24-96 hr, most of the label was found in non-extractable components, while small but significant amounts were present in MeGlx, MGlu, and free leucine. The level of leucine in storage protein of ungerminated seeds is similar to the maximum level of MeGlx found in germinated seeds; further correlations were observed in various peanut tissues between rapid accumulation of MeGlx and the presence of high levels of glyoxysomal enzymes (catalase and isocitrate lyase). These results suggest that during germination, most of the leucine in the seed storage protein is converted to MeGlx, possibly by a glyoxysomal oxidase system in cotyledons, whereas most of the free leucine for protein synthesis is formed de novo.

  15. Hypertrophy-Promoting Effects of Leucine Supplementation and Moderate Intensity Aerobic Exercise in Pre-Senescent Mice

    PubMed Central

    Xia, Zhi; Cholewa, Jason; Zhao, Yan; Yang, Yue-Qin; Shang, Hua-Yu; Guimarães-Ferreira, Lucas; Naimo, Marshall Alan; Su, Quan-Sheng; Zanchi, Nelo Eidy

    2016-01-01

    Several studies have indicated a positive influence of leucine supplementation and aerobic training on the aging skeletal muscle signaling pathways that control muscle protein balance and muscle remodeling. However, the effect of a combined intervention requires further clarification. Thirteen month old CD-1® mice were subjected to moderate aerobic exercise (45 min swimming per day with 3% body weight workload) and fed a chow diet with 5% leucine or 3.4% alanine for 8 weeks. Serum and plasma were prepared for glucose, urea nitrogen, insulin and amino acid profile analysis. The white gastrocnemius muscles were used for determination of muscle size and signaling proteins involved in protein synthesis and degradation. The results show that both 8 weeks of leucine supplementation and aerobic training elevated the activity of mTOR (mammalian target of rapamycin) and its downstream target p70S6K and 4E-BP1, inhibited the ubiquitin-proteasome system, and increased fiber cross-sectional area (CSA) in white gastrocnemius muscle. Moreover, leucine supplementation in combination with exercise demonstrated more significant effects, such as greater CSA, protein content and altered phosphorylation (suggestive of increased activity) of protein synthesis signaling proteins, in addition to lower expression of proteins involved in protein degradation compared to leucine or exercise alone. The current study shows moderate aerobic training combined with 5% leucine supplementation has the potential to increase muscle size in fast-twitch skeletal muscle during aging, potentially through increased protein synthesis and decreased protein breakdown. PMID:27144582

  16. Discovery and application of new bacterial strains for asymmetric synthesis of L-tert-butyl leucine in high enantioselectivity.

    PubMed

    Jin, Jian-Zhong; Chang, Dong-Liang; Zhang, Jie

    2011-06-01

    Discovery of new bacterial strains with fast identification in a miniaturized system was performed for the synthesis of optically active L-tert-butyl leucine. With tert-butyl leucine amide as nitrogen source, one bacterial strain with high conversion and high enantioselectivity was discovered among 120 isolated microorganisms from local soils and identified as Mycobacterium sp. JX009. Glucose and ammonium chloride were examined as the good carbon source and nitrogen source for the cells' growth separately. The cells grew better at 30 °C and at pH 7.5 with higher activity of 2,650 U/l in comparison with other conditions. Cells' stability was improved by immobilization on synthetic resin 0730 without pretreatment. Tert-butyl leucine amide (30 mM) was successfully hydrolyzed by immobilized cells and examined as the highest chemical concentration that cells could endure. After six reaction cycles, the immobilized cells retained 90% activity with production of L-tert-butyl leucine in 98% ee. The results firstly reported the application of new bacterial strain in the hydrolysis of tert-butyl leucine amide to produce optically active L-tert-butyl leucine in an efficient way with investigation in detail. PMID:21153891

  17. Physical exercise and a leucine-rich diet modulate the muscle protein metabolism in Walker tumor-bearing rats.

    PubMed

    Salomão, Emilianne M; Toneto, Aline T; Silva, Gisele O; Gomes-Marcondes, Maria Cristina C

    2010-01-01

    Leucine-supplemented diet can recover lean body mass and preserve muscle protein mass. Additionally, physical exercise can be an excellent alternative to improve the rehabilitation of cancer patients. Knowing these facts, we examined the effects of a leucine-rich diet with or without physical aerobic exercise on muscle protein metabolism in Walker tumor-bearing rats. Young rats were divided into 4 groups that did or did not perform light aerobic exercise (swim training) and were on a leucine-rich diet or a control diet for 2 mo. After this time, these animals were implanted or not with tumors (subcutaneously) following groups for either control diet or leucine-rich diet fed rats: control, trained, tumor-bearing, and trained tumor-bearing. Twenty-one days after implantation, the tumor growth induced a decrease in the muscle protein synthesis and increased the catabolic process, which was associated with an increase in the expression of the ubiquitin-proteasome subunits (20S, 19S, and 11S). In contrast, the exercise program minimized the muscle degradation process and increased muscle myosin content. Additionally, leucine supplementation also modulated proteasome subunits, especially the 19S and 11S. In summary, the exercise has beneficial effects by reducing tumor growth, leading to an improvement in protein turnover especially when in conjunction with a leucine-rich diet. PMID:21058197

  18. Hypertrophy-Promoting Effects of Leucine Supplementation and Moderate Intensity Aerobic Exercise in Pre-Senescent Mice.

    PubMed

    Xia, Zhi; Cholewa, Jason; Zhao, Yan; Yang, Yue-Qin; Shang, Hua-Yu; Guimarães-Ferreira, Lucas; Naimo, Marshall Alan; Su, Quan-Sheng; Zanchi, Nelo Eidy

    2016-01-01

    Several studies have indicated a positive influence of leucine supplementation and aerobic training on the aging skeletal muscle signaling pathways that control muscle protein balance and muscle remodeling. However, the effect of a combined intervention requires further clarification. Thirteen month old CD-1(®) mice were subjected to moderate aerobic exercise (45 min swimming per day with 3% body weight workload) and fed a chow diet with 5% leucine or 3.4% alanine for 8 weeks. Serum and plasma were prepared for glucose, urea nitrogen, insulin and amino acid profile analysis. The white gastrocnemius muscles were used for determination of muscle size and signaling proteins involved in protein synthesis and degradation. The results show that both 8 weeks of leucine supplementation and aerobic training elevated the activity of mTOR (mammalian target of rapamycin) and its downstream target p70S6K and 4E-BP1, inhibited the ubiquitin-proteasome system, and increased fiber cross-sectional area (CSA) in white gastrocnemius muscle. Moreover, leucine supplementation in combination with exercise demonstrated more significant effects, such as greater CSA, protein content and altered phosphorylation (suggestive of increased activity) of protein synthesis signaling proteins, in addition to lower expression of proteins involved in protein degradation compared to leucine or exercise alone. The current study shows moderate aerobic training combined with 5% leucine supplementation has the potential to increase muscle size in fast-twitch skeletal muscle during aging, potentially through increased protein synthesis and decreased protein breakdown. PMID:27144582

  19. Leucine supplementation is anti-atrophic during paradoxical sleep deprivation in rats.

    PubMed

    de Sá Souza, Helton; Antunes, Hanna Karen Moreira; Dáttilo, Murilo; Lee, Kil Sun; Mônico-Neto, Marcos; de Campos Giampa, Sara Quaglia; Phillips, Stuart M; Tufik, Sergio; de Mello, Marco Túlio

    2016-04-01

    The purpose of this study was to identify sleep deprivation-induced atrophy and the muscle-specific fiber types affected and to determine the effects of leucine supplementation on atrophy and pertinent portions of the pathways of muscle protein synthesis and degradation in rats. A total of 46 Wistar rats were distributed in four groups: control (CTL), leucine supplementation (LEU), sleep deprivation (SD), and leucine supplementation + sleep deprivation (LEU + SD). Leucine supplementation was by gavage (1.35 g/kg/daily), and the animals were subjected to SD for 96 h. Testosterone and corticosterone concentrations, along with proteins involved in protein synthesis and degradation and proteasome activity levels, were measured in the gastrocnemius (GA) muscle. Myosin ATPase staining was used to evaluate the different muscle fibers. After sleep deprivation, GA muscle and body masses decreased in the SD group compared to the CTL, LEU, and LEU + SD groups. There was no difference between groups in type I fiber cross-sectional area (CSA). The CSAs for type IIa fibers were lower in the SD and LEU + SD groups vs. the CTL and LEU groups, while the IIb fiber CSA was lower in the SD group vs. the CSAs in all other groups. The phospho (p)-Akt levels were lower in the SD and LEU + SD groups vs. the CTL and LEU groups. The p-mTORC1 levels were higher in the LEU, SD, and LEU + SD groups vs. the CTL group. The p-p70S6k levels were higher in the LEU and LEU + SD groups; the 4E-BP1 levels were higher in the SD and LEU + SD groups compared to those in the CTL and LEU groups, and the p-4E-BP1 levels were higher in the LEU and SD groups compared to those in the CTL group and even higher in the LEU + SD group compared to those in the LEU and SD groups. Ubiquitinated proteins, LC3, and p62/SQSTM, and proteasome activity levels were higher in the SD and LEU + SD groups vs. the LEU and CTL groups. Sleep deprivation led to the atrophy of IIa and IIb muscle fibers; however, leucine

  20. Leucine modulates peptide transport system-1 across the blood-brain barrier at the stereospecific site within the central nervous system.

    PubMed

    Banks, W A; Kastin, A J

    1991-04-01

    Previous results have shown that leucine injected into a cerebral ventricle (i.c.v.) can act as an allosteric regulator of peptide transport system-1 (PTS-1), the system that transports Tyr-Pro-Leu-Gly-NH2 (Tyr-MIF-1) and the enkephalins out of the central nervous system (CNS). D-Leucine appeared more potent than L-leucine. In the current study, dose-response curves were constructed for each compound after both intravenous (i.v.) and i.c.v. injection. Based on ED50 values after i.c.v. injection, D-leucine was about 200 times more potent than L-leucine in its inhibition of PTS-1, thereby confirming stereospecificity of the allosteric site. D- and L-Leucine were also more potent when given i.c.v. than when given i.v., suggesting that the site is located on the CNS side of the blood-brain barrier (BBB). The finding that D-leucine was less potent than L-leucine when given i.v. is also consistent with a CNS site of action because the L-isomer of leucine has been shown to be preferentially transported into the brain. These findings agree with the previous suggestion that some of the neurotoxic effects of leucine may be mediated through PTS-1 and could help explain how D-amino acids can exert opiate-related effects on the CNS. PMID:1676737

  1. F-box and leucine-rich repeat protein 5 (FBXL5) is required for maintenance of cellular and systemic iron homeostasis.

    PubMed

    Ruiz, Julio C; Walker, Scott D; Anderson, Sheila A; Eisenstein, Richard S; Bruick, Richard K

    2013-01-01

    Maintenance of cellular iron homeostasis requires post-transcriptional regulation of iron metabolism genes by iron regulatory protein 2 (IRP2). The hemerythrin-like domain of F-box and leucine-rich repeat protein 5 (FBXL5), an E3 ubiquitin ligase subunit, senses iron and oxygen availability and facilitates IRP2 degradation in iron replete cells. Disruption of the ubiquitously expressed murine Fbxl5 gene results in a failure to sense increased cellular iron availability, accompanied by constitutive IRP2 accumulation and misexpression of IRP2 target genes. FBXL5-null mice die during embryogenesis, although viability is restored by simultaneous deletion of the IRP2, but not IRP1, gene. Mice containing a single functional Fbxl5 allele behave like their wild type littermates when fed an iron-sufficient diet. However, unlike wild type mice that manifest decreased hematocrit and hemoglobin levels when fed a low-iron diet, Fbxl5 heterozygotes maintain normal hematologic values due to increased iron absorption. The responsiveness of IRP2 to low iron is specifically enhanced in the duodena of the heterozygotes and is accompanied by increased expression of the divalent metal transporter-1. These results confirm the role of FBXL5 in the in vivo maintenance of cellular and systemic iron homeostasis and reveal a privileged role for the intestine in their regulation by virtue of its unique FBXL5 iron sensitivity. PMID:23135277

  2. F-box and Leucine-rich Repeat Protein 5 (FBXL5) Is Required for Maintenance of Cellular and Systemic Iron Homeostasis*

    PubMed Central

    Ruiz, Julio C.; Walker, Scott D.; Anderson, Sheila A.; Eisenstein, Richard S.; Bruick, Richard K.

    2013-01-01

    Maintenance of cellular iron homeostasis requires post-transcriptional regulation of iron metabolism genes by iron regulatory protein 2 (IRP2). The hemerythrin-like domain of F-box and leucine-rich repeat protein 5 (FBXL5), an E3 ubiquitin ligase subunit, senses iron and oxygen availability and facilitates IRP2 degradation in iron replete cells. Disruption of the ubiquitously expressed murine Fbxl5 gene results in a failure to sense increased cellular iron availability, accompanied by constitutive IRP2 accumulation and misexpression of IRP2 target genes. FBXL5-null mice die during embryogenesis, although viability is restored by simultaneous deletion of the IRP2, but not IRP1, gene. Mice containing a single functional Fbxl5 allele behave like their wild type littermates when fed an iron-sufficient diet. However, unlike wild type mice that manifest decreased hematocrit and hemoglobin levels when fed a low-iron diet, Fbxl5 heterozygotes maintain normal hematologic values due to increased iron absorption. The responsiveness of IRP2 to low iron is specifically enhanced in the duodena of the heterozygotes and is accompanied by increased expression of the divalent metal transporter-1. These results confirm the role of FBXL5 in the in vivo maintenance of cellular and systemic iron homeostasis and reveal a privileged role for the intestine in their regulation by virtue of its unique FBXL5 iron sensitivity. PMID:23135277

  3. Blood-brain barrier permeability to leucine-enkephalin, D-alanine2-D-leucine5-enkephalin and their N-terminal amino acid (tyrosine).

    PubMed

    Zlokovic, B V; Begley, D J; Chain-Eliash, D G

    1985-06-10

    The permeability of the blood-brain barrier to [tyrosyl-3,5-3H]enkephalin-(5-L-leucine) (abbreviated to Leu-Enk) and of its synthetic analogue D-alanine2-[tyrosyl-3,5-3H]enkephalin-(5-D-leucine) (abbreviated to D-Ala2-D-Leu5-Enk) was studied, in the adult rat, by means of Oldendorf's27 intracarotid injection technique. The brain uptake index (BUI) corrected for residual vascular radioactivity was about the same for both peptides, indicating a low extraction from the blood during a 5- or 15-s period of exposure to the peptides. Transport of Leu-Enk was not saturated by unlabelled Enk at a concentration as high as 5 mM but was completely abolished by 5mM tyrosine and by the inhibitor of aminopeptidase activity, bacitracin (2 mM). Also the typical L-transport system substrate, 2-aminobicyclo(2,2,1)heptane-2 carboxylic acid (BCH)9 at 10 mM concentration markedly reduced (by 80%) Leu-Enk uptake by the brain. In contrast, brain uptake of D-Ala2-D-Leu5-Enk was reduced only to about one-half of its control value by bacitracin or by 25% by BCH. Brain uptake for L-tyrosine was typically large and markedly inhibited by BCH but not inhibited by 5 mM unlabelled Leu-Enk. These results show that the measurable but low first-pass extractions for enkephalins are not representative of the uptake of these peptides into the brain, but rather reflect their extreme sensitivity to enzymatic degradation with a release of the N-terminal tyrosine residue. The results also suggest that small amounts of D-Ala2-D-Leu5-Enk might cross the blood-brain barrier in an intact form.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3891014

  4. Leucine leucine-37 uses formyl peptide receptor-like 1 to activate signal transduction pathways, stimulate oncogenic gene expression, and enhance the invasiveness of ovarian cancer cells.

    PubMed

    Coffelt, Seth B; Tomchuck, Suzanne L; Zwezdaryk, Kevin J; Danka, Elizabeth S; Scandurro, Aline B

    2009-06-01

    Emerging evidence suggests that the antimicrobial peptide, leucine leucine-37 (LL-37), could play a role in the progression of solid tumors. LL-37 is expressed as the COOH terminus of human cationic antimicrobial protein-18 (hCAP-18) in ovarian, breast, and lung cancers. Previous studies have shown that the addition of LL-37 to various cancer cell lines in vitro stimulates proliferation, migration, and invasion. Similarly, overexpression of hCAP-18/LL-37 in vivo accelerates tumor growth. However, the receptor or receptors through which these processes are mediated have not been thoroughly examined. In the present study, expression of formyl peptide receptor-like 1 (FPRL1) was confirmed on ovarian cancer cells. Proliferation assays indicated that LL-37 does not signal through a G protein-coupled receptor, such as FPRL1, to promote cancer cell growth. By contrast, FPRL1 was required for LL-37-induced invasion through Matrigel. The peptide stimulated mitogen-activated protein kinase and Janus-activated kinase/signal transducers and activators of transcription signaling cascades and led to the significant activation of several transcription factors, through both FPRL1-dependent and FPRL1-independent pathways. Likewise, expression of some LL-37-stimulated genes was attenuated by the inhibition of FPRL1. Increased expression of CXCL10, EGF, and PDGF-BB as well as other soluble factors was confirmed from conditioned medium of LL-37-treated cells. Taken together, these data suggest that LL-37 potentiates a more aggressive behavior from ovarian cancer cells through its interaction with FPRL1. PMID:19491199

  5. Leucine Leucine-37 Uses Formyl Peptide Receptor–Like 1 to Activate Signal Transduction Pathways, Stimulate Oncogenic Gene Expression, and Enhance the Invasiveness of Ovarian Cancer Cells

    PubMed Central

    Coffelt, Seth B.; Tomchuck, Suzanne L.; Zwezdaryk, Kevin J.; Danka, Elizabeth S.; Scandurro, Aline B.

    2009-01-01

    Emerging evidence suggests that the antimicrobial peptide, leucine leucine-37 (LL-37), could play a role in the progression of solid tumors. LL-37 is expressed as the COOH terminus of human cationic antimicrobial protein-18 (hCAP-18) in ovarian, breast, and lung cancers. Previous studies have shown that the addition of LL-37 to various cancer cell lines in vitro stimulates proliferation, migration, and invasion. Similarly, overexpression of hCAP-18/LL-37 in vivo accelerates tumor growth. However, the receptor or receptors through which these processes are mediated have not been thoroughly examined. In the present study, expression of formyl peptide receptor–like 1 (FPRL1) was confirmed on ovarian cancer cells. Proliferation assays indicated that LL-37 does not signal through a G protein–coupled receptor, such as FPRL1, to promote cancer cell growth. By contrast, FPRL1 was required for LL-37–induced invasion through Matrigel. The peptide stimulated mitogen-activated protein kinase and Janus-activated kinase/signal transducers and activators of transcription signaling cascades and led to the significant activation of several transcription factors, through both FPRL1-dependent and FPRL1-independent pathways. Likewise, expression of some LL-37–stimulated genes was attenuated by the inhibition of FPRL1. Increased expression of CXCL10, EGF, and PDGF-BB as well as other soluble factors was confirmed from conditioned medium of LL-37–treated cells. Taken together, these data suggest that LL-37 potentiates a more aggressive behavior from ovarian cancer cells through its interaction with FPRL1. PMID:19491199

  6. Hypothalamic deep brain stimulation in the treatment of chronic cluster headache

    PubMed Central

    Leone, Massimo; Franzini, Angelo; Cecchini, Alberto Proietti; Broggi, Giovanni; Bussone, Gennaro

    2010-01-01

    Cluster headache (CH) is a short-lasting unilateral headache associated with ipsilateral craniofacial autonomic manifestations. A positron emission tomography (PET) study has shown that the posterior hypothalamus is activated during CH attacks, suggesting that hypothalamic hyperactivity plays a key role in CH pathophysiology. On this basis, stimulation of the ipsilateral posterior hypothalamus was hypothesized to counteract such hyperactivity to prevent intractable CH. Ten years after its introduction, hypothalamic stimulation has been proved to successfully prevent attacks in more than 60% of 58 hypothalamic implanted drug-resistant chronic CH patients. The implantation procedure has generally been proved to be safe, although it carries a small risk of brain haemorrhage. Long-term stimulation is safe, and nonsymptomatic impairment of orthostatic adaptation is the only noteworthy change. Microrecording studies will make it possible to better identify the target site. Neuroimaging investigations have shown that hypothalamic stimulation activates ipsilateral trigeminal complex, but with no immediate perceived sensation within the trigeminal distribution. Other studies on the pain threshold in chronically stimulated patients showed increased threshold for cold pain in the distribution of the first trigeminal branch ipsilateral to stimulation. These studies suggest that activation of the hypothalamus and of the trigeminal system are both necessary, but not sufficient to generate CH attacks. In addition to the hypothalamus, other unknown brain areas are likely to play a role in the pathophysiology of this illness. Hypothalamus implantation is associated with a small risk of intracerebral haemorrhage and must be performed by an expert neurosurgical team, in selected patients. PMID:21179610

  7. Differential Acute and Chronic Effects of Leptin on Hypothalamic Astrocyte Morphology and Synaptic Protein Levels

    PubMed Central

    García-Cáceres, Cristina; Fuente-Martín, Esther; Burgos-Ramos, Emma; Granado, Miriam; Frago, Laura M.; Barrios, Vicente; Horvath, Tamas

    2011-01-01

    Astrocytes participate in neuroendocrine functions partially through modulation of synaptic input density in the hypothalamus. Indeed, glial ensheathing of neurons is modified by specific hormones, thus determining the availability of neuronal membrane space for synaptic inputs, with the loss of this plasticity possibly being involved in pathological processes. Leptin modulates synaptic inputs in the hypothalamus, but whether astrocytes participate in this action is unknown. Here we report that astrocyte structural proteins, such as glial fibrillary acidic protein (GFAP) and vimentin, are induced and astrocyte morphology modified by chronic leptin administration (intracerebroventricular, 2 wk), with these changes being inversely related to modifications in synaptic protein densities. Similar changes in glial structural proteins were observed in adult male rats that had increased body weight and circulating leptin levels due to neonatal overnutrition (overnutrition: four pups/litter vs. control: 12 pups/litter). However, acute leptin treatment reduced hypothalamic GFAP levels and induced synaptic protein levels 1 h after administration, with no effect on vimentin. In primary hypothalamic astrocyte cultures leptin also reduced GFAP levels at 1 h, with an induction at 24 h, indicating a possible direct effect of leptin. Hence, one mechanism by which leptin may affect metabolism is by modifying hypothalamic astrocyte morphology, which in turn could alter synaptic inputs to hypothalamic neurons. Furthermore, the responses to acute and chronic leptin exposure are inverse, raising the possibility that increased glial activation in response to chronic leptin exposure could be involved in central leptin resistance. PMID:21343257

  8. Lessons from 8 years' experience of hypothalamic stimulation in cluster headache.

    PubMed

    Leone, M; Proietti Cecchini, A; Franzini, A; Broggi, G; Cortelli, P; Montagna, P; May, A; Juergens, T; Cordella, R; Carella, F; Bussone, G

    2008-07-01

    Neuroimaging studies in cluster headache (CH) patients have increased understanding of attack-associated events and provided clues to the pathophysiology of the condition. They have also suggested stimulation of the ipsilateral posterior inferior hypothalamus as a treatment for chronic intractable CH. After 8 years of experience, stimulation has proved successful in controlling the pain attacks in almost 60% of chronic CH patients implanted at various centres. Although hypothalamic implant is not without risks, it has generally been performed safely. Implantation affords an opportunity to perform microrecordings of individual posterior hypothalamic neurons. These studies are at an early stage, but suggest the possibility of identifying precisely the target site by its electrophysiological characteristics. Autonomic studies of patients undergoing posterior hypothalamic stimulation provide further evidence that long-term stimulation is safe, revealing that it can cause altered modulation of the mechanisms of orthostatic adaptation without affecting the baroreflex, cardiorespiratory interactions or efferent sympathetic and vagal functions. Chronically stimulated patients have an increased threshold for cold pain at the site of the first trigeminal branch ipsilateral to the stimulated side; when the stimulator is switched off, changes in sensory and pain thresholds do not occur immediately, suggesting that long-term stimulation is required to induce sensory and nociceptive changes. Posterior inferior hypothalamic stimulation is now established as a treatment for many chronic CH patients. The technique is shedding further light on the pathophysiology of the disease, and is also providing clues to functioning of the hypothalamus itself. PMID:18547215

  9. Adaptive Responses to Prochloraz Exposure in the Hypothalamic-Pituitary Gonadal Axis of Fathead Minnows

    EPA Science Inventory

    Exposure to endocrine disrupting chemicals can affect reproduction and development in both humans and wildlife. We are developing a mechanistic mathematical model of the hypothalamic-pituitary-gonadal (HPG) axis in female fathead minnows to predict doseresponse and time-course ...

  10. An indirect action contributes to c-fos induction in paraventricular hypothalamic nucleus by neuropeptide Y

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Neuropeptide Y (NPY) is a well-established orexigenic peptide and hypothalamic paraventricular nucleus (PVH) is one major brain site that mediates the orexigenic action of NPY. NPY induces abundant expression of C-Fos, an indicator for neuronal activation, in the PVH, which has been used extensively...

  11. Regulation of Energy Balance via BDNF Expressed in Nonparaventricular Hypothalamic Neurons.

    PubMed

    Yang, Haili; An, Juan Ji; Sun, Chao; Xu, Baoji

    2016-05-01

    Brain-derived neurotrophic factor (BDNF) expressed in the paraventricular hypothalamus (PVH) has been shown to play a key role in regulating energy intake and energy expenditure. BDNF is also expressed in other hypothalamic nuclei; however, the role in the control of energy balance for BDNF produced in these structures remains largely unknown. We found that deleting the Bdnf gene in the ventromedial hypothalamus (VMH) during embryogenesis using the Sf1-Cre transgene had no effect on body weight in mice. In contrast, deleting the Bdnf gene in the adult VMH using Cre-expressing virus led to significant hyperphagia and obesity. These observations indicate that the lack of a hyperphagia phenotype in the Sf1-Cre/Bdnf mutant mice is likely due to developmental compensation. To investigate the role of BDNF expressed in other hypothalamic areas, we employed the hypothalamus-specific Nkx2.1-Cre transgene to delete the Bdnf gene. We found that the Nkx2.1-Cre transgene could abolish BDNF expression in many hypothalamic nuclei, but not in the PVH, and that the resulting mutant mice developed modest obesity due to reduced energy expenditure. Thus, BDNF produced in the VMH plays a role in regulating energy intake. Furthermore, BDNF expressed in hypothalamic areas other than PVH and VMH is also involved in the control of energy expenditure. PMID:27003443

  12. SF-1 in the ventral medial hypothalamic nucleus: A key regulator of homeostasis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ventral medial hypothalamic nucleus (VMH) regulates food intake and body weight homeostasis. The nuclear receptor NR5A1 (steroidogenic factor 1; SF-1) is a transcription factor whose expression is highly restricted in the VMH and is required for the development of the nucleus. Neurons expressing...

  13. Feed intake of gilts following intracerebroventicular injection of the novel hypothalamic RFamide (RFa) neuropeptide, 26RFa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    RFamide (RFa) peptides have been implicated in a broad spectrum of biological processes including energy expenditure and feed intake. 26RFa is a recently discovered hypothalamic neuropeptide that altered the release of pituitary hormones and stimulated feed intake via a NPY-specific mechanism in rat...

  14. Hypothalamic Pituitary Adrenal Axis Functioning in Reactive and Proactive Aggression in Children

    ERIC Educational Resources Information Center

    Lopez-Duran, Nestor L.; Olson, Sheryl L.; Hajal, Nastassia J.; Felt, Barbara T.; Vazquez, Delia M.

    2009-01-01

    The purpose of this study was to examine the association between hypothalamic-pituitary-adrenal axis (HPA-axis) reactivity and proactive and reactive aggression in pre-pubertal children. After a 30-min controlled base line period, 73 7-year-old children (40 males and 33 females) were randomly assigned to one of two experimental tasks designed to…

  15. Functional test of the hypothalamic-pituitary-adrenal axis of sows housed in various environments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to assess the behavioral state of sows housed in various housing systems, and determine if the regulation of their hypothalamic-pituitary-adrenal axis had been altered. In Experiment 1, 33 sows were housed in either gestation stalls, group housed with no bedding, or ...

  16. Decreased hypothalamic growth hormone-releasing hormone content and pituitary responsiveness in hypothyroidism.

    PubMed Central

    Katakami, H; Downs, T R; Frohman, L A

    1986-01-01

    The effects of thyroidectomy (Tx) and thyroxine replacement (T4Rx) on pituitary growth hormone (GH) secretion and hypothalamic GH-releasing hormone (GRH) concentration were compared to define the mechanism of hypothyroid-associated GH deficiency. Thyroidectomized rats exhibited a complete loss of pulsatile GH secretion with extensive reduction in GRH responsiveness and pituitary GH content. Cultured pituitary cells from Tx rats exhibited reduced GRH sensitivity, maximal GH responsiveness, and intracellular cyclic AMP accumulation to GRH, while somatostatin (SRIF) suppressive effects on GH secretion were increased. Hypothalamic GRH content was also markedly reduced. T4Rx completely restored hypothalamic GRH content and spontaneous GH secretion despite only partial recovery of pituitary GH content, GRH and SRIF sensitivity, and intracellular cyclic AMP response to GRH. The results indicate multiple effects of hypothyroidism on GH secretion and suggest that a critical role of T4 in maintaining normal GH secretion, in addition to restoring GH synthesis, is related to its effect on hypothalamic GRH. Images PMID:2871046

  17. Gallium-67 breast uptake in a patient with hypothalamic granuloma (sarcoid)

    SciTech Connect

    Vazquez, R.; Oates, E.; Sarno, R.C.; Fay, J.; Gale, D.R.

    1988-01-01

    An unusual case is presented of bilateral breast uptake of (/sup 67/Ga)citrate in a patient with a hypothalamic granuloma in the absence of galactorrhea is presented. A possible mechanism for this incidental finding is elevated prolactin levels, as other causes of gallium breast uptake such as drug therapy, and intrinsic breast disease, were not present.

  18. Hypothalamic S1P/S1PR1 axis controls energy homeostasis.

    PubMed

    Silva, Vagner R R; Micheletti, Thayana O; Pimentel, Gustavo D; Katashima, Carlos K; Lenhare, Luciene; Morari, Joseane; Mendes, Maria Carolina S; Razolli, Daniela S; Rocha, Guilherme Z; de Souza, Claudio T; Ryu, Dongryeol; Prada, Patrícia O; Velloso, Lício A; Carvalheira, José B C; Pauli, José Rodrigo; Cintra, Dennys E; Ropelle, Eduardo R

    2014-01-01

    Sphingosine 1-phosphate receptor 1 (S1PR1) is a G-protein-coupled receptor for sphingosine-1-phosphate (S1P) that has a role in many physiological and pathophysiological processes. Here we show that the S1P/S1PR1 signalling pathway in hypothalamic neurons regulates energy homeostasis in rodents. We demonstrate that S1PR1 protein is highly enriched in hypothalamic POMC neurons of rats. Intracerebroventricular injections of the bioactive lipid, S1P, reduce food consumption and increase rat energy expenditure through persistent activation of STAT3 and the melanocortin system. Similarly, the selective disruption of hypothalamic S1PR1 increases food intake and reduces the respiratory exchange ratio. We further show that STAT3 controls S1PR1 expression in neurons via a positive feedback mechanism. Interestingly, several models of obesity and cancer anorexia display an imbalance of hypothalamic S1P/S1PR1/STAT3 axis, whereas pharmacological intervention ameliorates these phenotypes. Taken together, our data demonstrate that the neuronal S1P/S1PR1/STAT3 signalling axis plays a critical role in the control of energy homeostasis in rats. PMID:25255053

  19. Adaptive Response in Female Modeling of the Hypothalamic-pituitary-gonadal Axis

    EPA Science Inventory

    Exposure to endocrine disrupting chemicals can affect reproduction and development in both humans and wildlife. We are developing a mechanistic computational model of the hypothalamic-pituitary-gonadal (HPG) axis in female fathead minnows to predict dose-response and time-course ...

  20. Hypothalamic obesity after treatment for craniopharyngioma: the importance of the home environment.

    PubMed

    Meijneke, Ruud W H; Schouten-van Meeteren, Antoinette Y N; de Boer, Nienke Y; van Zundert, Suzanne; van Trotsenburg, Paul A S; Stoelinga, Femke; van Santen, Hanneke M

    2015-01-01

    Hypothalamic obesity after treatment for craniopharyngioma is a well-recognized, severe problem. Treatment of hypothalamic obesity is difficult and often frustrating for the patient, the parents and the professional care-giver. Because hypothalamic obesity is caused by an underlying medical disorder, it is often assumed that regular diet and exercise are not beneficial to reduce the extraordinarily high body mass index, and in fact, lifestyle interventions have been shown to be insufficient in case of extreme hypothalamic obesity. Nevertheless, it is important to realize that also in this situation, informal care delivered by the family and appropriate parenting styles are required to minimize the obesity problem. We present a case in which weight gain in the home situation was considered unstoppable, and a very early mortality due to complications of the severe increasing obesity was considered inevitable. A permissive approach toward food intake became leading with rapid weight increase since a restrictive lifestyle was considered a senseless burden for the child. By admission to our hospital for a longer period of time, weight reduction was realized, and the merely permissive approach could be changed into active purposeful care by adequate information, instruction, guidance and encouragement of the affected child and her parents. This case illustrates that, although this type of obesity has a pathological origin, parental and environmental influences remain of extreme importance. PMID:25381948

  1. Hypothalamic mitochondrial dysfunction associated with anorexia in the anx/anx mouse

    PubMed Central

    Lindfors, Charlotte; Nilsson, Ida A. K.; Garcia-Roves, Pablo M.; Zuberi, Aamir R.; Karimi, Mohsen; Donahue, Leah Rae; Roopenian, Derry C.; Mulder, Jan; Uhlén, Mathias; Ekström, Tomas J.; Davisson, Muriel T.; Hökfelt, Tomas G. M.; Schalling, Martin; Johansen, Jeanette E.

    2011-01-01

    The anorectic anx/anx mouse exhibits disturbed feeding behavior and aberrances, including neurodegeneration, in peptidergic neurons in the appetite regulating hypothalamic arcuate nucleus. Poor feeding in infants, as well as neurodegeneration, are common phenotypes in human disorders caused by dysfunction of the mitochondrial oxidative phosphorylation system (OXPHOS). We therefore hypothesized that the anorexia and degenerative phenotypes in the anx/anx mouse could be related to defects in the OXPHOS. In this study, we found reduced efficiency of hypothalamic OXPHOS complex I assembly and activity in the anx/anx mouse. We also recorded signs of increased oxidative stress in anx/anx hypothalamus, possibly as an effect of the decreased hypothalamic levels of fully assembled complex I, that were demonstrated by native Western blots. Furthermore, the Ndufaf1 gene, encoding a complex I assembly factor, was genetically mapped to the anx interval and found to be down-regulated in anx/anx mice. These results suggest that the anorexia and hypothalamic neurodegeneration of the anx/anx mouse are associated with dysfunction of mitochondrial complex I. PMID:22025706

  2. Chronic cortisol suppresses pituitary and hypothalamic peptide message expression in pigtailed macaques.

    PubMed

    Szot, P; Wilkinson, C W; White, S S; Leverenz, J B; Greenup, J L; Colasurdo, E A; Peskind, E R; Raskind, M A

    2004-01-01

    The effects of chronic elevations in circulating glucocorticoids on the expression of peptides and peptide receptors of the hypothalamic-pituitary-adrenal (HPA) axis have been studied extensively in rodents, but they have not been examined in primates. To determine the responses of the HPA axis in primates to elevated cortisol, hypothalamic and pituitary tissue from normal older pigtailed macaques (Macaca nemestrina) that had received daily oral administration of cortisol or placebo for 1 year were studied. Pro-opiomelanocortin in the anterior pituitary and corticotropin-releasing factor (CRF) mRNA expression in the hypothalamic paraventricular nucleus (PVN) were significantly reduced in cortisol-treated monkeys in comparison with controls. CRF receptor 1 (CRF-R1) expression in the anterior pituitary and arginine vasopressin mRNA expression in the PVN were unchanged by chronic cortisol administration. Sustained elevation of circulating glucocorticoids results in suppression of HPA peptide and peptide receptor expression in the PVN and anterior pituitary similar to those found in rodents. Chronic therapeutic administration of glucocorticoids in humans may have unintended consequences for hypothalamic and pituitary function. PMID:15145089

  3. A neuroendocrine role for chemerin in hypothalamic remodelling and photoperiodic control of energy balance

    PubMed Central

    Helfer, Gisela; Ross, Alexander W.; Thomson, Lynn M.; Mayer, Claus D.; Stoney, Patrick N.; McCaffery, Peter J.; Morgan, Peter J.

    2016-01-01

    Long-term and reversible changes in body weight are typical of seasonal animals. Thyroid hormone (TH) and retinoic acid (RA) within the tanycytes and ependymal cells of the hypothalamus have been implicated in the photoperiodic response. We investigated signalling downstream of RA and how this links to the control of body weight and food intake in photoperiodic F344 rats. Chemerin, an inflammatory chemokine, with a known role in energy metabolism, was identified as a target of RA. Gene expression of chemerin (Rarres2) and its receptors were localised within the tanycytes and ependymal cells, with higher expression under long (LD) versus short (SD) photoperiod, pointing to a physiological role. The SD to LD transition (increased food intake) was mimicked by 2 weeks of ICV infusion of chemerin into rats. Chemerin also increased expression of the cytoskeletal protein vimentin, implicating hypothalamic remodelling in this response. By contrast, acute ICV bolus injection of chemerin on a 12 h:12 h photoperiod inhibited food intake and decreased body weight with associated changes in hypothalamic neuropeptides involved in growth and feeding after 24 hr. We describe the hypothalamic ventricular zone as a key site of neuroendocrine regulation, where the inflammatory signal, chemerin, links TH and RA signaling to hypothalamic remodeling. PMID:27225311

  4. MATERNAL ATRAZINE (ATR) ALTERS HYPOTHALAMIC DOPAMINE (HYP-DA) AND SERUM PROLACTIN (SPRL) IN MALE PUPS

    EPA Science Inventory

    Maternal Atrazine (ATR) alters hypothalamic dopamine (HYP-DA) and serum prolactin (sPRL) in male pups. 1Christopher Langdale, 2Tammy Stoker and 2Ralph Cooper. 1 Dept. of Cell Biology, North Carolina State University College of Veterinary Medicine, Raleigh, NC. 2 Endocrinology ...

  5. Adolescent Survivors of Hurricane Katrina: A Pilot Study of Hypothalamic-Pituitary-Adrenal Axis Functioning

    ERIC Educational Resources Information Center

    Pfefferbaum, Betty; Tucker, Phebe; Nitiéma, Pascal

    2015-01-01

    Background: The hypothalamic-pituitary-adrenal (HPA) axis constitutes an important biological component of the stress response commonly studied through the measurement of cortisol. Limited research has examined HPA axis dysregulation in youth exposed to disasters. Objective: This study examined HPA axis activation in adolescent Hurricane Katrina…

  6. Electrophysiological properties and thermosensitivity of mouse preoptic and anterior hypothalamic neurons in culture.

    PubMed

    Tabarean, I V; Conti, B; Behrens, M; Korn, H; Bartfai, T

    2005-01-01

    Responses of mouse preoptic and anterior hypothalamic neurons to variations of temperature are key elements in regulating the setpoint of homeotherms. The goal of the present work was to assess the relevance of culture preparations for investigating the cellular mechanisms underlying thermosensitivity in hypothalamic cells. Our working hypothesis was that some of the main properties of preoptic/anterior hypothalamic neurons in culture are similar to those reported by other authors in slice preparations. Indeed, cultured preoptic/anterior hypothalamic neurons share many of the physiological and morphological properties of neurons in hypothalamic slices. They display heterogenous dendritic arbors and somatic shapes. Most of them are GABAergic and their activity is synaptically driven by the activation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate receptors. Active membrane properties include a depolarizing "sag" in response to hyperpolarization, and a low threshold spike, which is present in a majority of cells and is generated by T-type Ca2+ channels. In a fraction of the cells, the low threshold spike repeats rhythmically, either spontaneously, or in response to depolarization. The background synaptic noise in cultured neurons is characterized by the presence of numerous postsynaptic potentials which can be easily distinguished from the baseline, thus providing an opportunity for assessing their possible roles in thermosensitivity. An unexpected finding was that GABA-A receptors can generate both hyper- and depolarizing postsynaptic potentials in the same neuron. About 20% of the spontaneously firing preoptic/anterior hypothalamic neurons are warm-sensitive. Warming (32-41 degrees C) depolarizes some cells, a phenomenon which is Na+-dependent and tetrodotoxin-insensitive. The increased firing rate of warm-sensitive cells in response to warming can be prepotential and/or synaptically driven. Overall, our data suggest that a warm

  7. Expanding indications for the extended endoscopic endonasal approach to hypothalamic gliomas: preliminary report.

    PubMed

    Zoli, Matteo; Mazzatenta, Diego; Valluzzi, Adelaide; Marucci, Gianluca; Acciarri, Nicola; Pasquini, Ernesto; Frank, Giorgio

    2014-01-01

    Object In the last decade the indications for the endoscopic endonasal approach have been progressively expanded to include lesions that have not been traditionally considered amenable to resection through the transsphenoidal route. In this study, the authors analyze their experience with hypothalamic gliomas treated via the endoscopic endonasal approach. Methods Consecutive cases of hypothalamic gliomas treated since 2007 via an endoscopic endonasal approach were reviewed. Preoperative and postoperative neuroimaging as well as endocrinological, neurological, and visual symptoms were analyzed to assess the surgical outcome. Signs and symptoms of hypothalamic dysfunction including body mass index (BMI), memory, sleep-wake rhythm, and polyphagia were prospectively collected pre- and postoperatively to assess hypothalamic function. Quality of life was evaluated using the Katz scale. Results In the initial phase the endoscopic endonasal approach was adopted in 3 cases with a palliative intent, to obtain a biopsy sample or for debulking of the mass followed by radio- or chemotherapy. In 2 later cases it was successfully adopted to achieve gross-total tumor resection. Complications consisted of 2 postoperative CSF leaks, which required an endoscopic endonasal reintervention. Visual deficit improved in 3 cases and normalized in the other 2. Four patients developed diabetes insipidus, and 3 an anterior panhypopituitarism. All patients had a moderate increase in BMI. No patients presented with any other signs of hypothalamic damage, and their quality of life at follow-up is normal. Conclusions Despite the limitations of a short follow-up and small sample, the authors' early experience with the endoscopic endonasal approach has revealed it to be a direct, straightforward, and safe approach to third ventricle astrocytomas. It allowed the authors to perform tumor resection with the same microsurgical technique: dissecting the tumor with 2 hands, performing a central debulking

  8. Membrane potential dye imaging of ventromedial hypothalamus neurons from adult mice to study glucose sensing.

    PubMed

    Vazirani, Reema P; Fioramonti, Xavier; Routh, Vanessa H

    2013-01-01

    Studies of neuronal activity are often performed using neurons from rodents less than 2 months of age due to the technical difficulties associated with increasing connective tissue and decreased neuronal viability that occur with age. Here, we describe a methodology for the dissociation of healthy hypothalamic neurons from adult-aged mice. The ability to study neurons from adult-aged mice allows the use of disease models that manifest at a later age and might be more developmentally accurate for certain studies. Fluorescence imaging of dissociated neurons can be used to study the activity of a population of neurons, as opposed to using electrophysiology to study a single neuron. This is particularly useful when studying a heterogeneous neuronal population in which the desired neuronal type is rare such as for hypothalamic glucose sensing neurons. We utilized membrane potential dye imaging of adult ventromedial hypothalamic neurons to study their responses to changes in extracellular glucose. Glucose sensing neurons are believed to play a role in central regulation of energy balance. The ability to study glucose sensing in adult rodents is particularly useful since the predominance of diseases related to dysfunctional energy balance (e.g. obesity) increase with age. PMID:24326343

  9. Membrane Potential Dye Imaging of Ventromedial Hypothalamus Neurons From Adult Mice to Study Glucose Sensing

    PubMed Central

    Vazirani, Reema P.; Fioramonti, Xavier; Routh, Vanessa H.

    2013-01-01

    Studies of neuronal activity are often performed using neurons from rodents less than 2 months of age due to the technical difficulties associated with increasing connective tissue and decreased neuronal viability that occur with age. Here, we describe a methodology for the dissociation of healthy hypothalamic neurons from adult-aged mice. The ability to study neurons from adult-aged mice allows the use of disease models that manifest at a later age and might be more developmentally accurate for certain studies. Fluorescence imaging of dissociated neurons can be used to study the activity of a population of neurons, as opposed to using electrophysiology to study a single neuron. This is particularly useful when studying a heterogeneous neuronal population in which the desired neuronal type is rare such as for hypothalamic glucose sensing neurons. We utilized membrane potential dye imaging of adult ventromedial hypothalamic neurons to study their responses to changes in extracellular glucose. Glucose sensing neurons are believed to play a role in central regulation of energy balance. The ability to study glucose sensing in adult rodents is particularly useful since the predominance of diseases related to dysfunctional energy balance (e.g. obesity) increase with age. PMID:24326343

  10. Litter Size Variation in Hypothalamic Gene Expression Determines Adult Metabolic Phenotype in Brandt's Voles (Lasiopodomys brandtii)

    PubMed Central

    Zhang, Xue-Ying; Zhang, Qiang; Wang, De-Hua

    2011-01-01

    Background Early postnatal environments may have long-term and potentially irreversible consequences on hypothalamic neurons involved in energy homeostasis. Litter size is an important life history trait and negatively correlated with milk intake in small mammals, and thus has been regarded as a naturally varying feature of the early developmental environment. Here we investigated the long-term effects of litter size on metabolic phenotype and hypothalamic neuropeptide mRNA expression involved in the regulation of energy homeostasis, using the offspring reared from large (10–12) and small (3–4) litter sizes, of Brandt's voles (Lasiopodomys brandtii), a rodent species from Inner Mongolia grassland in China. Methodology/Principal Findings Hypothalamic leptin signaling and neuropeptides were measured by Real-Time PCR. We showed that offspring reared from small litters were heavier at weaning and also in adulthood than offspring from large litters, accompanied by increased food intake during development. There were no significant differences in serum leptin levels or leptin receptor (OB-Rb) mRNA in the hypothalamus at weaning or in adulthood, however, hypothalamic suppressor of cytokine signaling 3 (SOCS3) mRNA in adulthood increased in small litters compared to that in large litters. As a result, the agouti-related peptide (AgRP) mRNA increased in the offspring from small litters. Conclusions/Significance These findings support our hypothesis that natural litter size has a permanent effect on offspring metabolic phenotype and hypothalamic neuropeptide expression, and suggest central leptin resistance and the resultant increase in AgRP expression may be a fundamental mechanism underlying hyperphagia and the increased risk of overweight in pups of small litters. Thus, we conclude that litter size may be an important and central determinant of metabolic fitness in adulthood. PMID:21637839

  11. Effects of auricular stimulation on feeding-related hypothalamic neuronal activity in normal and obese rats.

    PubMed

    Shiraishi, T; Onoe, M; Kojima, T; Sameshima, Y; Kageyama, T

    1995-01-01

    It is known that auriculotherapy occasionally affects dramatic body weight reduction for obese patients, although the physiological and anorexigenic functions are not clear. Effects of auricular stimulation on feeding-related lateral (LHA) and ventromedial (VMH) hypothalamic neuronal activity in normal and experimental (hypothalamic and dietary) obese rats were investigated. The LHA and/or VMH neuronal activity were recorded from feeding-related regions in Wistar SPF/VAF male and experimental (hypothalamic and dietary) obese rats, anesthetized with urethane-chloralose, under stereotaxic coordination. Recording was through 3 M KCI glass microelectrodes, while stimulating the ipsilateral vagal innervated region of the auricle. This is equivalent to the cavum conchae in the human, and was identified by resistance less than 10-50 k omega. The stimulating electrode was a stainless steel ear acupuncture (0.12 x 2.0 mm). The latency of potentials evoked in the LHA by unilateral stimulation of a specific site in the ear was 28.1 +/- 3.3 ms (8-92, n = 41). LHA neuronal activity was depressed 45.6% (n = 12, p < 0.01), and VMH activity was excited (60.5%, n = 18, p < 0.01). The auricular acupuncture stimulation clearly modulates feeding-related hypothalamic neuronal activity of experimental (both hypothalamic and dietary) obese rats. These auricle acupuncture stimulation effects were correlated to the degree of obesity. In conclusion, the results suggest that auricular acupuncture stimulation may not reduce appetite, but is more likely concerned with satiation formation and preservation. Thus, auricular acupuncture should be more effective on obese rats than on normal rats. PMID:7895091

  12. Activation of hypothalamic gono-like neurons in female rats during estrus☆

    PubMed Central

    Ren, Xiaoxuan; Wang, Shaojun; Rong, Peijing; Zhu, Bing

    2012-01-01

    In mammals, gonadal function is controlled by the activity of hypothalamic gonadotropin-releasing hormone neurons, which control the secretion of adenohypophyseal and gonadal hormones. However, there are a number of unanswered questions in relation to gonadal function. It is currently unknown how erotogenic stimulation of the genitals influences the subpopulation of hypothalamic medial preoptic area neurons, antidromically identified as projecting to the median eminence at different periods of the estrous cycle. Additionally, the distinctiveness of hypothalamic medial preoptic area neurons, with respect to methods of feedback control by exogenous hormones, is also unknown. In this study, spontaneous discharges from individual neurons encountered within the medial preoptic area, gono-like neurons, were recorded extracellularly using glass microelectrodes. To confirm the cellular and histochemical properties of the recording units, antidromic stimulation was performed using a side-by-side bipolar stimulating electrode placed into the median eminence, alongside microiontophoretic injections of the conventional tracer, horseradish peroxidase. In addition, further immunohistochemical analyses were performed. Results showed that elevated gono-neuron activity was accompanied by increased background activity and greater responses to erotogenic stimuli during estrus. Application of clitoral traction stimulation resulted in increased activation of the gono-like neurons. This neuronal activity was noticeably inhibited by β-estradiol administration. Immunohistochemical analyses revealed the presence of gonadotropin-releasing hormone-reactive protein in hypothalamic cells in which electrophysiological recordings were taken. Thus, medial preoptic area neurons represent the subset of hypothalamic gonadotropin-releasing hormone neurons described from brain slices in vitro, and might serve as a useful physiological model to form the basis of future in vivo studies. PMID:25337091

  13. Prolonged leucine supplementation does not augment muscle mass or affect glycemic control in elderly type 2 diabetic men.

    PubMed

    Leenders, Marika; Verdijk, Lex B; van der Hoeven, Letty; van Kranenburg, Janneau; Hartgens, Fred; Wodzig, Will K W H; Saris, Wim H M; van Loon, Luc J C

    2011-06-01

    The loss of muscle mass with aging has been, at least partly, attributed to a blunted muscle protein synthetic response to food intake. Leucine coingestion has been reported to stimulate postprandial insulin release and augment postprandial muscle protein accretion. We assessed the clinical benefits of 6 mo of leucine supplementation in elderly, type 2 diabetes patients. Sixty elderly males with type 2 diabetes (age, 71 ± 1 y; BMI, 27.3 ± 0.4 kg/m(2)) were administered 2.5 g L-leucine (n = 30) or a placebo (n = 30) with each main meal during 6 mo of nutritional intervention (7.5 g/d leucine or placebo). Body composition, muscle fiber characteristics, muscle strength, glucose homeostasis, and basal plasma amino acid and lipid concentrations were assessed prior to, during, and after intervention. Lean tissue mass did not change or differ between groups and at 0, 3, and 6 mo were 61.9 ± 1.1, 62.2 ± 1.1, and 62.0 ± 1.0 kg, respectively, in the leucine group and 62.2 ± 1.3, 62.2 ± 1.3, and 62.2 ± 1.3 kg in the placebo group. There also were no changes in body fat percentage, muscle strength, and muscle fiber type characteristics. Blood glycosylated hemoglobin did not change or differ between groups and was 7.1 ± 0.1% in the leucine group and 7.2 ± 0.2% in the placebo group. Consistent with this, oral glucose insulin sensitivity and plasma lipid concentrations did not change or differ between groups. We conclude that prolonged leucine supplementation (7.5 g/d) does not modulate body composition, muscle mass, strength, glycemic control, and/or lipidemia in elderly, type 2 diabetes patients who habitually consume adequate dietary protein. PMID:21525248

  14. Age-Associated Weight Gain, Leptin, and SIRT1: A Possible Role for Hypothalamic SIRT1 in the Prevention of Weight Gain and Aging through Modulation of Leptin Sensitivity

    PubMed Central

    Sasaki, Tsutomu

    2015-01-01

    The hypothalamus is the principal regulator of body weight and energy balance. It modulates both energy intake and energy expenditure by sensing the energy status of the body through neural inputs from the periphery as well as direct humoral inputs. Leptin, an adipokine, is one of the humoral factors responsible for alerting the hypothalamus that enough energy is stored in the periphery. Plasma leptin levels are positively linked to adiposity; leptin suppress energy intake and stimulates energy expenditure. However, prolonged increases in plasma leptin levels due to obesity cause leptin resistance, affecting both leptin access to hypothalamic neurons and leptin signal transduction within hypothalamic neurons. Decreased sensing of peripheral energy status through leptin may lead to a positive energy balance and gradual gains in weight and adiposity, further worsening leptin resistance. Leptin resistance, increased adiposity, and weight gain are all associated with aging in both humans and animals. Central insulin resistance is associated with similar observations. Therefore, improving the action of humoral factors in the hypothalamus may prevent gradual weight gain, especially during middle age. SIRT1 is a NAD+-dependent protein deacetylase with numerous substrates, including histones, transcription factors, co-factors, and various enzymes. SIRT1 improves both leptin sensitivity and insulin sensitivity by decreasing the levels of several molecules that impair leptin and insulin signal transduction. SIRT1 and NAD+ levels decrease with age in the hypothalamus; increased hypothalamic SIRT1 levels prevent age-associated weight gain and improve leptin sensitivity in mice. Therefore, preventing the age-dependent loss of SIRT1 function in the hypothalamus could improve the action of humoral factors in the hypothalamus as well as central regulation of energy balance. PMID:26236282

  15. Leucine disposal rate for assessment of amino acid metabolism in maintenance hemodialysis patients

    PubMed Central

    Denny, Gerald B.; Deger, Serpil M.; Chen, Guanhua; Bian, Aihua; Sha, Feng; Booker, Cindy; Kesler, Jaclyn T.; David, Sthuthi; Ellis, Charles D.; Ikizler, T. Alp

    2016-01-01

    Background Protein energy wasting (PEW) is common in patients undergoing maintenance hemodialysis (MHD) and closely associated with poor outcomes. Insulin resistance and associated alterations in amino acid metabolism are potential pathways leading to PEW. We hypothesized that the measurement of leucine disposal during a hyperinsulinemic- euglycemic-euaminoacidemic clamp (HEAC) procedure would accurately measure the sensitivity to insulin for its actions on concomitant carbohydrate and protein metabolism in MHD patients. Methods We examined 35 MHD patients and 17 control subjects with normal kidney function by hyperinsulinemic-euglycemic clamp (HEGC) followed by HEAC clamp procedure to obtain leucine disposal rate (LDR) along with isotope tracer methodology to assess whole body protein turnover. Results The glucose disposal rate (GDR) by HEGC was 5.1 ± 2.1 mg/kg/min for the MHD patients compared to 6.3 ± 3.9 mg/kg/min for the controls (p = 0.38). The LDR during HEAC was 0.09 ± 0.03 mg/kg/min for the MHD patients compared to 0.11 ± 0.05 mg/kg/min for the controls (p = 0.009). The LDR level was correlated with whole body protein synthesis (r = 0.25; p = 0.08), with whole body protein breakdown (r = −0.38 p = 0.01) and net protein balance (r = 0.85; p < 0.001) in the overall study population. Correlations remained significant in subgroup analysis. The GDR derived by HEGC and LDR correlated well in the controls (r = 0.79, p < 0.001), but less so in the MHD patients (r = 0.58, p < 0.001). Conclusions Leucine disposal rate reliably measures amino acid utilization in MHD patients and controls in response to high dose insulin. PMID:27413537

  16. A Membrane Leucine Heptad Contributes to Trafficking, Signaling, and Transformation by Latent Membrane Protein 1▿

    PubMed Central

    Lee, Jisook; Sugden, Bill

    2007-01-01

    Latent membrane protein 1 (LMP1) of Epstein Barr virus (EBV) is important for maintaining proliferation of EBV-infected B cells. LMP1, unlike its cellular counterpart, CD40, signals without a ligand and is largely internal to the plasma membrane. In order to understand how LMP1 initiates its ligand-independent signaling, we focused on a leucine heptad in LMP1's first membrane-spanning domain that was shown to be necessary for LMP1's signaling through NF-κB. LZ1EBV, a recombinant EBV genetically altered to express LZ1, a derivative of LMP1 in which a leucine heptad was replaced with alanines, transformed B cells with 56% of wild-type (wt) EBV's efficiency, demonstrating the importance of this heptad. To elucidate the mechanism by which this domain contributes to the functions of LMP1, the properties of the wt and LZ1 were compared in transfected cells. LZ1 failed to home to lipid rafts as efficiently as did wt LMP1. The distribution of tagged derivatives of LZ1 also differed from that of wt LMP1 in transfected cells. LZ1's defect in homing to lipid rafts and altered trafficking likely underlie the defect in transformation of LZ1EBV. While the third and fourth membrane-spanning domains of LMP1 foster its trafficking to the Golgi, the leucine heptad within the first membrane-spanning domain contributes to its trafficking, particularly to internal rafts. B cells that are successfully transformed by LZ1EBV have the same average number of viral genomes and the same fraction of cells with capped LZ1 at the cell surface but express 50% more of the LZ1 allele than wt infected cells. PMID:17581993

  17. Differential regulation of protein synthesis in skeletal muscle and liver of neonatal pigs by leucine through an mTORC1-dependent pathway.

    PubMed

    Suryawan, Agus; Nguyen, Hanh V; Almonaci, Rosemarie D; Davis, Teresa A

    2012-02-28

    Neonatal growth is characterized by a high protein synthesis rate that is largely due to an enhanced sensitivity to the postprandial rise in insulin and amino acids, especially leucine. The mechanism of leucine's action in vivo is not well understood. In this study, we investigated the effect of leucine infusion on protein synthesis in skeletal muscle and liver of neonatal pigs. To evaluate the mode of action of leucine, we used rapamycin, an inhibitor of mammalian target of rapamycin (mTOR) complex-1 (mTORC1). Overnight-fasted 7-day-old piglets were treated with rapamycin for 1 hour and then infused with leucine (400 μmol·kg(-1)·h(-1)) for 1 hour. Leucine infusion increased the rate of protein synthesis, and ribosomal protein S6 kinase 1 (S6K1) and eukaryotic initiation factor (eIF) 4E-binding protein-1 (4E-BP1) phosphorylation in gastrocnemius and masseter muscles (P < 0.05), but not in the liver. The leucine-induced stimulation of protein synthesis and S6K1 and 4E-BP1 phosphorylation were completely blocked by rapamycin, suggesting that leucine action is by an mTORC1-dependent mechanism. Neither leucine nor rapamycin had any effect on the activation of the upstream mTORC1 regulators, AMP-activated protein kinase and protein kinase B, in skeletal muscle or liver. The activation of eIF2α and elongation factor 2 was not affected by leucine or rapamycin, indicating that these two pathways are not limiting steps of leucine-induced protein synthesis. These results suggest that leucine stimulates muscle protein synthesis in neonatal pigs by inducing the activation of mTORC1 and its downstream pathway leading to mRNA translation. PMID:22675606

  18. Long-term remission with rituximab in refractory leucine-rich glioma inactivated 1 antibody encephalitis.

    PubMed

    Brown, J William L; Martin, Peter J; Thorpe, John W; Michell, Andrew W; Coles, Alasdair J; Cox, Amanda L; Vincent, Angela; Zandi, Michael S

    2014-06-15

    Autoimmune encephalitis associated with antibodies to leucine-rich glioma inactivated 1 (LGI1) is recently described and there is a lack of detailed reports on the treatment of relapsing or refractory cases and long-term outcomes. Two case reports are presented. Both cases had faciobrachial dystonic seizures (FBDS) and received rituximab after relapsing or refractory disease. Both cases achieved sustained clinical remission of up to 15 and 56 months respectively. Rituximab use allowed withdrawal of corticosteroids and was well tolerated. Randomized clinical trials are needed in LGI1 encephalitis and other autoimmune encephalitides. PMID:24703099

  19. Structure-Based Design of Type II Inhibitors Applied to Maternal Embryonic Leucine Zipper Kinase.

    PubMed

    Johnson, Christopher N; Adelinet, Christophe; Berdini, Valerio; Beke, Lijs; Bonnet, Pascal; Brehmer, Dirk; Calo, Frederick; Coyle, Joseph E; Day, Phillip J; Frederickson, Martyn; Freyne, Eddy J E; Gilissen, Ron A H J; Hamlett, Christopher C F; Howard, Steven; Meerpoel, Lieven; Mevellec, Laurence; McMenamin, Rachel; Pasquier, Elisabeth; Patel, Sahil; Rees, David C; Linders, Joannes T M

    2015-01-01

    A novel Type II kinase inhibitor chemotype has been identified for maternal embryonic leucine zipper kinase (MELK) using structure-based ligand design. The strategy involved structural characterization of an induced DFG-out pocket by protein-ligand X-ray crystallography and incorporation of a slender linkage capable of bypassing a large gate-keeper residue, thus enabling design of molecules accessing both hinge and induced pocket regions. Optimization of an initial hit led to the identification of a low-nanomolar, cell-penetrant Type II inhibitor suitable for use as a chemical probe for MELK. PMID:25589926

  20. Potent, selective and orally bioavailable leucine-rich repeat kinase 2 (LRRK2) inhibitors.

    PubMed

    Greshock, Thomas J; Sanders, John M; Drolet, Robert E; Rajapakse, Hemaka A; Chang, Ronald K; Kim, Boyoung; Rada, Vanessa L; Tiscia, Heather E; Su, Hua; Lai, Ming-Tain; Sur, Sylvie M; Sanchez, Rosa I; Bilodeau, Mark T; Renger, John J; Kern, Jonathan T; McCauley, John A

    2016-06-01

    Familial Parkinson's disease cases have recently been associated with the leucine rich repeat kinase 2 (LRRK2) gene. It has been hypothesized that inhibition of the LRRK2 protein may have the potential to alter disease pathogenesis. A dihydrobenzothiophene series of potent, selective, orally bioavailable LRRK2 inhibitors were identified from a high-throughput screen of the internal Merck sample collection. Initial SAR studies around the core established the series as a tractable small molecule lead series of LRRK2 inhibitors for potential treatment of Parkinson's disease. It was also found that incorporation of a lactam into the core drastically improved the CNS and DMPK properties of these small molecules. PMID:27106707

  1. Thermodynamic characteristics of the heparin-leucine-CaCl2 system in a diluted physiological solution

    NASA Astrophysics Data System (ADS)

    Nikolaeva, L. S.; Belov, G. V.; Rulev, Yu. A.; Semenov, A. N.

    2013-03-01

    Chemical equilibria in aqueous solutions of high-molecular weight heparin (Na4hep) and leucine (HLeu) are calculated through the mathematical modeling of chemical equilibria based on representative experimental pH titration data. In addition, chemical equilibria in the CaCl2-Na4hep-HLeu-H2O-NaCl system in the presence of 0.154M NaCl background electrolyte at a temperature of 37°C in the range of 2.30 ≤ pH ≤ 10.50 and initial concentrations of basic components n × 10-3 M ( n ≤ 4).

  2. Structure-Based Design of Type II Inhibitors Applied to Maternal Embryonic Leucine Zipper Kinase

    PubMed Central

    2014-01-01

    A novel Type II kinase inhibitor chemotype has been identified for maternal embryonic leucine zipper kinase (MELK) using structure-based ligand design. The strategy involved structural characterization of an induced DFG-out pocket by protein–ligand X-ray crystallography and incorporation of a slender linkage capable of bypassing a large gate-keeper residue, thus enabling design of molecules accessing both hinge and induced pocket regions. Optimization of an initial hit led to the identification of a low-nanomolar, cell-penetrant Type II inhibitor suitable for use as a chemical probe for MELK. PMID:25589926

  3. Additive insulinogenic action of Opuntia ficus-indica cladode and fruit skin extract and leucine after exercise in healthy males

    PubMed Central

    2013-01-01

    Background Oral intake of a specific extract of Opuntia ficus-indica cladode and fruit skin (OpunDia™) (OFI) has been shown to increase serum insulin concentration while reducing blood glucose level for a given amount of glucose ingestion after an endurance exercise bout in healthy young volunteers. However, it is unknown whether OFI-induced insulin stimulation after exercise is of the same magnitude than the stimulation by other insulinogenic agents like leucine as well as whether OFI can interact with those agents. Therefore, the aims of the present study were: 1) to compare the degree of insulin stimulation by OFI with the effect of leucine administration; 2) to determine whether OFI and leucine have an additive action on insulin stimulation post-exercise. Methods Eleven subjects participated in a randomized double-blind cross-over study involving four experimental sessions. In each session the subjects successively underwent a 2-h oral glucose tolerance test (OGTT) after a 30-min cycling bout at ~70% VO2max. At t0 and t60 during the OGTT, subjects ingested 75 g glucose and capsules containing either 1) a placebo; 2) 1000 mg OFI; 3) 3 g leucine; 4) 1000 mg OFI + 3 g leucine. Blood samples were collected before and at 30-min intervals during the OGTT for determination of blood glucose and serum insulin. Results Whereas no effect of leucine was measured, OFI reduced blood glucose at t90 by ~7% and the area under the glucose curve by ~15% and increased serum insulin concentration at t90 by ~35% compared to placebo (P<0.05). From t60 to the end of the OGTT, serum insulin concentration was higher in OFI+leucine than in placebo which resulted in a higher area under the insulin curve (+40%, P<0.05). Conclusion Carbohydrate-induced insulin stimulation post-exercise can be further increased by the combination of OFI with leucine. OFI and leucine could be interesting ingredients to include together in recovery drinks to resynthesize muscle glycogen faster post

  4. Functional characterization of leucine transport induced in Xenopus laevis oocytes injected with mRNA isolated from midguts of lepidopteran larvae (Philosamia cynthia).

    PubMed

    Sacchi, V F; Perego, C; Magagnin, S

    1995-04-01

    The injection of poly(A)+ mRNA prepared from Philosamia cynthia midgut caused time- and dose-dependent increases of leucine transport in Xenopus laevis oocytes, with an increase in leucine uptake 1.5-3 times that of oocytes injected with water. When the NaCl concentration was reduced from 100 to 5 mmol l-1, the difference between mRNA- and water-injected oocytes was greater and a fourfold increase of L-leucine uptake was measured. D-Leucine (10 mmol l-1) completely inhibited the induced uptake of 0.1 mmol l-1 L-leucine. The newly expressed component of L-leucine uptake increased at alkaline pH and was abolished by incubation for 15 min with 15 mmol l-1 phenylglyoxal. The mean Km values, calculated using Na+ activation curves of leucine uptake, were 23.3 +/- 6.1 mmol l-1 in water-injected oocytes and 0.4 +/- 0.2 mmol l-1 for the newly expressed component of leucine uptake in mRNA-injected oocytes. On the basis of these results, we conclude that the increase of L-leucine uptake in mRNA-injected oocytes was due to the expression of a new transport system, which differs from the endogenous ones and shares many features with that found previously in Philosamia cynthia midgut. PMID:7730757

  5. The role of the N-terminal leucine residue in snake venom cardiotoxin II (Naja naja atra).

    PubMed

    Wu, C Y; Chen, W C; Ho, C L; Chen, S T; Wang, K T

    1997-04-28

    The N-terminal leucine residue of snake venom cardiotoxin II (CTX II) (Naja naja atra) was systematically replaced with D-leucine (CTXII-L1-D-L), glycine (CTXII-L1G) or deleted [CTXII-(2-60)] to study the role of leucine residue in CTX II molecule. CTX II, CTXL1-D-L, CTXL1G and CTX(2-60) were produced by chemical synthesis method and purified by high performance liquid chromatography. Owing to folding problem in CTXII-(2-60), only CTX II, CTXII-L1-D-L and CTXII-L1G were produced in a pure form and characterized by amino acid analysis, mass spectrometry and peptide mapping. In the structural aspect, changing the Leu-1 by D-Leu or Gly causes a drastic alteration in the whole CTX II structure as detected by circular dichroism, 1-anilino-naphthalene-8-sulfonate (ANS) fluorescence assay. In the functional aspect, both CTXII-L1-D-L and CTXII-L1G are still retained substantial biological activity of CTX II. Therefore, the results indicate that both the chirality and the side-chain of the N-terminal leucine residue of CTX II are important elements in maintaining the whole CTX II structure. In addition, this study is the first report in elucidating the reason why the first N-terminal residue of most CTXs (90.3%) is leucine residue. PMID:9168920

  6. Investigations on particle surface characteristics vs. dispersion behaviour of L-leucine coated carrier-free inhalable powders.

    PubMed

    Raula, Janne; Thielmann, Frank; Naderi, Majid; Lehto, Vesa-Pekka; Kauppinen, Esko I

    2010-01-29

    Aerosol microparticles of salbutamol sulphate are gas-phase coated with an amino acid L-leucine. Depending of the saturated state of L-leucine, the coating is formed by the surface diffusion of L-leucine molecules within a droplet or by the physical vapour deposition (PVD) of L-leucine or by the combination thereof. The PVD coated particles showed excellent aerosolization characteristics in a carrier-free powder delivery from an inhaler. The aerosolization of the fine powders is compared with surface energy parameters analysed by inverse gas chromatography (IGC). The dispersion testing is conducted by a Inhalation Simulator using a fast inhalation profile with inhalation flow rate of 67 l min(-1). It is found that the powder emission is affected by the morphology, surface roughness (asperity size and density) of the particles and acidity of particle surface. The latter affects the dispersion and dose repeatability of fine powder in a case if L-leucine content is high enough. However, there is no direct correlation between dispersive surface energies and aerosolization performances of the powders. Crucial factors for the improved aerosolization rely weakly on surface acid-base properties but strongly on particle morphology and fine-scale surface roughness. PMID:19879344

  7. Effect of hyperglucagonemia on whole-body leucine metabolism in immature pigs before and during a meal

    SciTech Connect

    Ostaszewski, P.; Nissen, S. )

    1988-03-01

    Leucine metabolism was measured isotopically in 12 immature female pigs to assess the effect of acute hyperglucagonemia on leucine kinetics in both the fed and fasting states. After an overnight fast, immature pigs were infused with {alpha}-({sup 3}H)ketoisocaproate and ({sup 14}C)leucine. After a 2-h equilibration period, an infusion of either saline or 7 pg {center dot} kg{sup {minus}1} {center dot} min{sup {minus}1} of glucagon was begun, which increased plasma glucagon from {approximately}140 to {approximately}640 pg/ml and doubled the insulin concentrations. Two hours later, pigs were fed small meals to which (5,5,5-{sup 2}H{sub 3})leucine was added to trace absorption. By subtracting absorption from total leucine flux, an estimate of endogenous proteolysis during the meal was made. In the fasting state, glucagon increased proteolysis and increased oxidation. No significant glucagon-related changes in any other flux parameters occurred in the fasting state. Ingestion of the meals caused oxidation to increase 41% in control animals, whereas in glucagon-infused animals, oxidation increased 84%. Additional, animals infused with glucagon suppressed endogenous proteolysis 43% after the meal compared with 55% decrease in control animals. These data indicate that glucagon stimulates whole-body proteolysis in both the fasting and fed states.

  8. Designed heterodimerizing leucine zippers with a ranger of pIs and stabilities up to 10(-15) M.

    PubMed

    Moll, J R; Ruvinov, S B; Pastan, I; Vinson, C

    2001-03-01

    We have designed a heterodimerizing leucine zipper system to target a radionuclide to prelocalized noninternalizing tumor-specific antibodies. The modular nature of the leucine zipper allows us to iteratively use design rules to achieve specific homodimer and heterodimer affinities. We present circular-dichroism thermal denaturation measurements on four pairs of heterodimerizing leucine zippers. These peptides are 47 amino acids long and contain four or five pairs of electrostatically attractive g <--> e' (i, i' +5) interhelical heterodimeric interactions. The most stable heterodimer consists of an acidic leucine zipper and a basic leucine zipper that melt as homodimers in the micro (T(m) = 28 degrees C) or nanomolar (T(m) = 40 degrees C) range, respectively, but heterodimerize with a T(m) >90 degrees C, calculated to represent femtamolar affinities. Modifications to this pair of acidic and basic zippers, designed to destabilize homodimerization, resulted in peptides that are unstructured monomers at 4 microM and 6 degrees C but that heterodimerize with a T(m) = 74 degrees C or K(d(37)) = 1.1 x 10(-11) M. A third heterodimerizing pair was designed to have a more neutral isoelectric focusing point (pI) and formed a heterodimer with T(m) = 73 degrees C. We can tailor this heterodimerizing system to achieve pharmacokinetics aimed at optimizing targeted killing of cancer cells. PMID:11344333

  9. Pervasive sensing

    NASA Astrophysics Data System (ADS)

    Nagel, David J.

    2000-11-01

    The coordinated exploitation of modern communication, micro- sensor and computer technologies makes it possible to give global reach to our senses. Web-cameras for vision, web- microphones for hearing and web-'noses' for smelling, plus the abilities to sense many factors we cannot ordinarily perceive, are either available or will be soon. Applications include (1) determination of weather and environmental conditions on dense grids or over large areas, (2) monitoring of energy usage in buildings, (3) sensing the condition of hardware in electrical power distribution and information systems, (4) improving process control and other manufacturing, (5) development of intelligent terrestrial, marine, aeronautical and space transportation systems, (6) managing the continuum of routine security monitoring, diverse crises and military actions, and (7) medicine, notably the monitoring of the physiology and living conditions of individuals. Some of the emerging capabilities, such as the ability to measure remotely the conditions inside of people in real time, raise interesting social concerns centered on privacy issues. Methods for sensor data fusion and designs for human-computer interfaces are both crucial for the full realization of the potential of pervasive sensing. Computer-generated virtual reality, augmented with real-time sensor data, should be an effective means for presenting information from distributed sensors.

  10. Numbers Sense

    ERIC Educational Resources Information Center

    Kathotia, Vinay

    2009-01-01

    This article reports on work undertaken by schools as part of Qualifications and Curriculum Authority's (QCA's) "Engaging mathematics for all learners" project. The goal was to use in the classroom, materials and approaches from a Royal Institution (Ri) Year 10 master-class, "Number Sense", which was inspired by examples from Michael Blastland and…

  11. Sonic hedgehog lineage in the mouse hypothalamus: from progenitor domains to hypothalamic regions

    PubMed Central

    2012-01-01

    Background The hypothalamus is a brain region with essential functions for homeostasis and energy metabolism, and alterations of its development can contribute to pathological conditions in the adult, like hypertension, diabetes or obesity. However, due to the anatomical complexity of the hypothalamus, its development is not well understood. Sonic hedgehog (Shh) is a key developmental regulator gene expressed in a dynamic pattern in hypothalamic progenitor cells. To obtain insight into hypothalamic organization, we used genetic inducible fate mapping (GIFM) to map the lineages derived from Shh-expressing progenitor domains onto the four rostrocaudally arranged hypothalamic regions: preoptic, anterior, tuberal and mammillary. Results Shh-expressing progenitors labeled at an early stage (before embryonic day (E)9.5) contribute neurons and astrocytes to a large caudal area including the mammillary and posterior tuberal regions as well as tanycytes (specialized median eminence glia). Progenitors labeled at later stages (after E9.5) give rise to neurons and astrocytes of the entire tuberal region and in particular the ventromedial nucleus, but not to cells in the mammillary region and median eminence. At this stage, an additional Shh-expressing domain appears in the preoptic area and contributes mostly astrocytes to the hypothalamus. Shh-expressing progenitors do not contribute to the anterior region at any stage. Finally, we show a gradual shift from neurogenesis to gliogenesis, so that progenitors expressing Shh after E12.5 generate almost exclusively hypothalamic astrocytes. Conclusions We define a fate map of the hypothalamus, based on the dynamic expression of Shh in the hypothalamic progenitor zones. We provide evidence that the large neurogenic Shh-expressing progenitor domains of the ventral diencephalon are continuous with those of the midbrain. We demonstrate that the four classical transverse zones of the hypothalamus have clearly defined progenitor domains

  12. Positive selection in the leucine-rich repeat domain of Gro1 genes in Solanum species.

    PubMed

    Ruggieri, Valentino; Nunziata, Angelina; Barone, Amalia

    2014-12-01

    In pathogen resistant plants, solvent-exposed residues in the leucine-rich repeat (LRR) proteins are thought to mediate resistance by recognizing plant pathogen elicitors. In potato, the gene Gro1-4 confers resistance to Globodera rostochiensis. The investigation of variability in different copies of this gene represents a good model for the verification of positive selection mechanisms. Two datasets of Gro1 LRR sequences were constructed, one derived from the Gro1-4 gene, belonging to different cultivated and wild Solanum species, and the other belonging to paralogues of a resistant genotype. Analysis of nonsynonymous to synonymous substitution rates (K(a)/K(s)) highlighted 14 and six amino acids with K(a)/K(s) >1 in orthologue and paralogue datasets, respectively. Selection analysis revealed that the leucine-rich regions accumulate variability in a very specific way, and we found that some combinations of amino acids in these sites might be involved in pathogen recognition. The results confirm previous studies on positive selection in the LRR domain of R protein in Arabidopsis and other model plants and extend these to wild Solanum species. Moreover, positively selected sites in the Gro1 LRR domain show that coevolution mainly occurred in two regions on the internal surface of the three-dimensional horseshoe structure of the domain, albeit with different evolutionary forces between paralogues and orthologues. PMID:25572234

  13. Structure and Mechanism of Isopropylmalate Dehydrogenase from Arabidopsis thaliana: INSIGHTS ON LEUCINE AND ALIPHATIC GLUCOSINOLATE BIOSYNTHESIS.

    PubMed

    Lee, Soon Goo; Nwumeh, Ronald; Jez, Joseph M

    2016-06-24

    Isopropylmalate dehydrogenase (IPMDH) and 3-(2'-methylthio)ethylmalate dehydrogenase catalyze the oxidative decarboxylation of different β-hydroxyacids in the leucine- and methionine-derived glucosinolate biosynthesis pathways, respectively, in plants. Evolution of the glucosinolate biosynthetic enzyme from IPMDH results from a single amino acid substitution that alters substrate specificity. Here, we present the x-ray crystal structures of Arabidopsis thaliana IPMDH2 (AtIPMDH2) in complex with either isopropylmalate and Mg(2+) or NAD(+) These structures reveal conformational changes that occur upon ligand binding and provide insight on the active site of the enzyme. The x-ray structures and kinetic analysis of site-directed mutants are consistent with a chemical mechanism in which Lys-232 activates a water molecule for catalysis. Structural analysis of the AtIPMDH2 K232M mutant and isothermal titration calorimetry supports a key role of Lys-232 in the reaction mechanism. This study suggests that IPMDH-like enzymes in both leucine and glucosinolate biosynthesis pathways use a common mechanism and that members of the β-hydroxyacid reductive decarboxylase family employ different active site features for similar reactions. PMID:27137927

  14. Restricted leucine zipper dimerization and specificity of DNA recognition of the melanocyte master regulator MITF.

    PubMed

    Pogenberg, Vivian; Ogmundsdóttir, Margrét H; Bergsteinsdóttir, Kristín; Schepsky, Alexander; Phung, Bengt; Deineko, Viktor; Milewski, Morlin; Steingrímsson, Eiríkur; Wilmanns, Matthias

    2012-12-01

    Microphthalmia-associated transcription factor (MITF) is a master regulator of melanocyte development and an important oncogene in melanoma. MITF heterodimeric assembly with related basic helix-loop-helix leucine zipper transcription factors is highly restricted, and its binding profile to cognate DNA sequences is distinct. Here, we determined the crystal structure of MITF in its apo conformation and in the presence of two related DNA response elements, the E-box and M-box. In addition, we investigated mouse and human Mitf mutations to dissect the functional significance of structural features. Owing to an unusual three-residue shift in the leucine zipper register, the MITF homodimer shows a marked kink in one of the two zipper helices to allow an out-of-register assembly. Removal of this insertion relieves restricted heterodimerization by MITF and permits assembly with the transcription factor MAX. Binding of MITF to the M-box motif is mediated by an unusual nonpolar interaction by Ile212, a residue that is mutated in mice and humans with Waardenburg syndrome. As several related transcription factors have low affinity for the M-box sequence, our analysis unravels how these proteins discriminate between similar target sequences. Our data provide a rational basis for targeting MITF in the treatment of important hereditary diseases and cancer. PMID:23207919

  15. MHJ_0461 is a multifunctional leucine aminopeptidase on the surface of Mycoplasma hyopneumoniae.

    PubMed

    Jarocki, Veronica M; Santos, Jerran; Tacchi, Jessica L; Raymond, Benjamin B A; Deutscher, Ania T; Jenkins, Cheryl; Padula, Matthew P; Djordjevic, Steven P

    2015-01-01

    Aminopeptidases are part of the arsenal of virulence factors produced by bacterial pathogens that inactivate host immune peptides. Mycoplasma hyopneumoniae is a genome-reduced pathogen of swine that lacks the genetic repertoire to synthesize amino acids and relies on the host for availability of amino acids for growth. M. hyopneumoniae recruits plasmin(ogen) onto its cell surface via the P97 and P102 adhesins and the glutamyl aminopeptidase MHJ_0125. Plasmin plays an important role in regulating the inflammatory response in the lungs of pigs infected with M. hyopneumoniae. We show that recombinant MHJ_0461 (rMHJ_0461) functions as a leucine aminopeptidase (LAP) with broad substrate specificity for leucine, alanine, phenylalanine, methionine and arginine and that MHJ_0461 resides on the surface of M. hyopneumoniae. rMHJ_0461 also binds heparin, plasminogen and foreign DNA. Plasminogen bound to rMHJ_0461 was readily converted to plasmin in the presence of tPA. Computational modelling identified putative DNA and heparin-binding motifs on solvent-exposed sites around a large pore on the LAP hexamer. We conclude that MHJ_0461 is a LAP that moonlights as a multifunctional adhesin on the cell surface of M. hyopneumoniae. PMID:25589579

  16. Complex coacervates obtained from peptide leucine and gum arabic: formation and characterization.

    PubMed

    Gulão, Eliana da S; de Souza, Clitor J F; Andrade, Cristina T; Garcia-Rojas, Edwin E

    2016-03-01

    In this study, interactions between polypeptide-leucine (0.2% w/w) and gum arabic (0.03, 0.06, 0.09, 0.12, and 0.15% w/w) were examined at concentrations of NaCl (0, 0.01, 0.25, 0.3, 0.5mol/l) and at different pH values (from 1.0 to 12.0). Formation of insoluble complex coacervates was highest at pH 4.0. At pH 2.0, which is the pKa of the gum Arabic, the dissociation of precipitate occurred. The pHØ2 positively shifted with the addition of higher concentrations of salt. Samples containing 0.2% PL and 0.03% GA and no salt had higher turbidity and increased formation of precipitates showing greater turbidity and particle sizes. The Fourier transform infrared spectroscopy confirms the complex coacervate formation of leucine and gum arabic, and rheological measurements suggest the elastic behavior of 0.2% PL and 0.03% GA complex. Overall, the study suggests that complex coacervates of PLs could be one feasible ways of incorporating amino acids in food products. PMID:26471607

  17. A novel D-leucine-containing Conus peptide: diverse conformational dynamics in the contryphan family.

    PubMed

    Jacobsen, R B; Jimenez, E C; De la Cruz, R G; Gray, W R; Cruz, L J; Olivera, B M

    1999-08-01

    A Conus peptide family (the contryphans) is noteworthy because of the presence of a post-translationally modified D-amino acid in all members of the family. A new contryphan peptide, Leu-contryphan-P, was isolated from the venom of Conus purpurascens; the sequence of this peptide is: Gly-Cys-Val-D-Leu-Leu-Pro-Trp-Cys-OH. This is the first known occurrence of D-leucine in a Conus peptide. The discovery of Leu-contryphan-P suggests that there may be branches of the contryphan peptide family that diverge much more in sequence than previously anticipated. Several natural contryphans provide dramatic examples of interconversion between multiple conformational states in small constrained peptides. The contryphans that have 4-trans-hydroxyproline and D-tryptophan in positions 3 and 4, respectively, exhibit two peaks under reverse-phase HPLC conditions, indicating interconversion between two discrete conformations. However, [L-Trp4]contryphan-Sm (with L-Trp substituted for D-Trp) exhibits a single, broad peak that elutes later than the natural peptide, suggesting that D-Trp stabilizes a conformation in which hydrophobic residues are buried. Leucontryphan-P which has valine and D-leucine instead of 4-trans-hydroxyproline and D-tryptophan shows only a single peak that elutes much later than the other contryphans. PMID:10461743

  18. MHJ_0461 is a multifunctional leucine aminopeptidase on the surface of Mycoplasma hyopneumoniae

    PubMed Central

    Jarocki, Veronica M.; Santos, Jerran; Tacchi, Jessica L.; Raymond, Benjamin B. A.; Deutscher, Ania T.; Jenkins, Cheryl; Padula, Matthew P.; Djordjevic, Steven P.

    2015-01-01

    Aminopeptidases are part of the arsenal of virulence factors produced by bacterial pathogens that inactivate host immune peptides. Mycoplasma hyopneumoniae is a genome-reduced pathogen of swine that lacks the genetic repertoire to synthesize amino acids and relies on the host for availability of amino acids for growth. M. hyopneumoniae recruits plasmin(ogen) onto its cell surface via the P97 and P102 adhesins and the glutamyl aminopeptidase MHJ_0125. Plasmin plays an important role in regulating the inflammatory response in the lungs of pigs infected with M. hyopneumoniae. We show that recombinant MHJ_0461 (rMHJ_0461) functions as a leucine aminopeptidase (LAP) with broad substrate specificity for leucine, alanine, phenylalanine, methionine and arginine and that MHJ_0461 resides on the surface of M. hyopneumoniae. rMHJ_0461 also binds heparin, plasminogen and foreign DNA. Plasminogen bound to rMHJ_0461 was readily converted to plasmin in the presence of tPA. Computational modelling identified putative DNA and heparin-binding motifs on solvent-exposed sites around a large pore on the LAP hexamer. We conclude that MHJ_0461 is a LAP that moonlights as a multifunctional adhesin on the cell surface of M. hyopneumoniae. PMID:25589579

  19. Leucine Zipper-bearing Kinase promotes axon growth in mammalian central nervous system neurons

    PubMed Central

    Chen, Meifan; Geoffroy, Cédric G.; Wong, Hetty N.; Tress, Oliver; Nguyen, Mallorie T.; Holzman, Lawrence B.; Jin, Yishi; Zheng, Binhai

    2016-01-01

    Leucine Zipper-bearing Kinase (LZK/MAP3K13) is a member of the mixed lineage kinase family with high sequence identity to Dual Leucine Zipper Kinase (DLK/MAP3K12). While DLK is established as a key regulator of axonal responses to injury, the role of LZK in mammalian neurons is poorly understood. By gain- and loss-of-function analyses in neuronal cultures, we identify LZK as a novel positive regulator of axon growth. LZK signals specifically through MKK4 and JNKs among MAP2Ks and MAPKs respectively in neuronal cells, with JNK activity positively regulating LZK protein levels. Neuronal maturation or activity deprivation activates the LZK-MKK4-JNK pathway. LZK and DLK share commonalities in signaling, regulation, and effects on axon extension. Furthermore, LZK-dependent regulation of DLK protein expression and the lack of additive effects on axon growth upon co-manipulation suggest complex functional interaction and cross-regulation between these two kinases. Together, our data support the possibility for two structurally related MAP3Ks to work in concert to mediate axonal responses to external insult or injury in mammalian CNS neurons. PMID:27511108

  20. The Native GCN4 Leucine-Zipper Domain Does Not Uniquely Specify a Dimeric Oligomerization State

    PubMed Central

    Oshaben, Kaylyn M.; Salari, Reza; McCaslin, Darrell R.; Chong, Lillian T.; Horne, W. Seth

    2012-01-01

    The dimerization domain of the yeast transcription factor GCN4, one of the first coiled-coil proteins to be structurally characterized at high resolution, has served as the basis for numerous fundamental studies on α-helical folding. Mutations in the GCN4 leucine zipper are known to change its preferred oligomerization state from dimeric to trimeric or tetrameric; however, the wild-type sequence has been assumed to encode a two-chain assembly exclusively. Here we demonstrate that the GCN4 coiled-coil domain can populate either a dimer or trimer fold, depending on environment. We report high-resolution crystal structures of the wild-type sequence in dimeric and trimeric assemblies. Biophysical measurements suggest populations of both oligomerization states under certain experimental conditions in solution. We use parallel tempering molecular dynamics simulations on the microsecond timescale to compare the stability of the dimer and trimer folded states in isolation. In total, our results suggest that the folding behavior of the well-studied GCN4 leucine-zipper domain is more complex than was previously appreciated. Our results have implications in ongoing efforts to establish predictive algorithms for coiled-coil folds and the selection of coiled-coil model systems for design and mutational studies where oligomerization state specificity is an important consideration. PMID:23116373

  1. A nuclear factor containing the leucine-rich repeats expressed in murine cerebellar neurons.

    PubMed Central

    Matsuoka, K; Taoka, M; Satozawa, N; Nakayama, H; Ichimura, T; Takahashi, N; Yamakuni, T; Song, S Y; Isobe, T

    1994-01-01

    A nuclear protein, termed leucine-rich acidic nuclear protein (LANP), has been isolated from among rat cerebellar proteins whose expression was transiently increased during an early stage of postnatal development. The amino acid sequence, deduced from its cDNA, showed that LANP contains 247 amino acids consisting of two distinct structural domains: the N-terminal domain characterized by "leucine-rich repeat," which is found in many eukaryotic proteins and which potentially functions in mediating protein-protein interactions, and the C-terminal domain characterized by a cluster of acidic amino acids with a putative nuclear localization signal. Immunohistochemical study using an antibody against LANP revealed that the protein is localized mainly in nuclei of Purkinje cells. In the rat cerebellum on postnatal day 7, LANP mRNA was expressed moderately in the external granule and Purkinje cells and weakly in the internal granule cells. The expression in these cells, especially in Purkinje cells, increased in the second postnatal week and thereafter decreased to an adult level. The structural characteristics, localization, and the stage- and cell type-specific expression suggest a potential role of LANP in a signal transduction pathway that directs differentiation of cerebellar neurons. Images PMID:7937870

  2. Leucine Zipper-bearing Kinase promotes axon growth in mammalian central nervous system neurons.

    PubMed

    Chen, Meifan; Geoffroy, Cédric G; Wong, Hetty N; Tress, Oliver; Nguyen, Mallorie T; Holzman, Lawrence B; Jin, Yishi; Zheng, Binhai

    2016-01-01

    Leucine Zipper-bearing Kinase (LZK/MAP3K13) is a member of the mixed lineage kinase family with high sequence identity to Dual Leucine Zipper Kinase (DLK/MAP3K12). While DLK is established as a key regulator of axonal responses to injury, the role of LZK in mammalian neurons is poorly understood. By gain- and loss-of-function analyses in neuronal cultures, we identify LZK as a novel positive regulator of axon growth. LZK signals specifically through MKK4 and JNKs among MAP2Ks and MAPKs respectively in neuronal cells, with JNK activity positively regulating LZK protein levels. Neuronal maturation or activity deprivation activates the LZK-MKK4-JNK pathway. LZK and DLK share commonalities in signaling, regulation, and effects on axon extension. Furthermore, LZK-dependent regulation of DLK protein expression and the lack of additive effects on axon growth upon co-manipulation suggest complex functional interaction and cross-regulation between these two kinases. Together, our data support the possibility for two structurally related MAP3Ks to work in concert to mediate axonal responses to external insult or injury in mammalian CNS neurons. PMID:27511108

  3. Unexpected Diversity of pepA Genes Encoding Leucine Aminopeptidases in Sediments from a Freshwater Lake

    PubMed Central

    Tsuboi, Shun; Yamamura, Shigeki; Imai, Akio; Iwasaki, Kazuhiro

    2016-01-01

    We herein designed novel PCR primers for universal detection of the pepA gene, which encodes the representative leucine aminopeptidase gene, and investigated the genetic characteristics and diversity of pepA genes in sediments of hypereutrophic Lake Kasumigaura, Japan. Most of the amino acid sequences deduced from the obtained clones (369 out of 370) were related to PepA-like protein sequences in the M17 family of proteins. The developed primers broadly detected pepA-like clones associated with diverse bacterial phyla—Alpha-, Beta-, Gamma-, and Deltaproteobacteria, Acidobacteria, Actinobacteria, Aquificae, Chlamydiae, Chloroflexi, Cyanobacteria, Firmicutes, Nitrospirae, Planctomycetes, and Spirochetes as well as the archaeal phylum Thaumarchaeota, indicating that prokaryotes in aquatic environments possessing leucine aminopeptidase are more diverse than previously reported. Moreover, prokaryotes related to the obtained pepA-like clones appeared to be r- and K-strategists, which was in contrast to our previous findings showing that the neutral metalloprotease gene clones obtained were related to the r-strategist genus Bacillus. Our results suggest that an unprecedented diversity of prokaryotes with a combination of different proteases participate in sedimentary proteolysis. PMID:26936797

  4. Non-universal decoding of the leucine codon CUG in several Candida species.

    PubMed Central

    Ohama, T; Suzuki, T; Mori, M; Osawa, S; Ueda, T; Watanabe, K; Nakase, T

    1993-01-01

    It has been reported that CUG, a universal leucine codon, is read as serine in an asporogenic yeast, Candida cylindracea. The distribution of this non-universal genetic code in various yeast species was studied using an in vitro translation assay system with a synthetic messenger RNA containing CUG codons in-frame. It was found that CUG is used as a serine codon in six out of the fourteen species examined, while it is used for leucine in the remaining eight. The tRNA species responsible for the translation of codon CUG as serine was detected in all the six species in which CUG is translated as serine. The grouping according to the CUG codon assignments in these yeast species shows a good correlation with physiological classification by the chain lengths of the isoprenoid moiety of ubiquinone and the cell-wall sugar contained in the yeasts. The six Candida species examined in which CUG is used as serine belong to one distinct group in Hemiascomycetes. PMID:8371978

  5. Stimulating effects of inosine, uridine and glutamine on the tissue distribution of radioactive D-leucine in tumor bearing mice.

    PubMed

    Goto, R; Takeda, A; Tamemasa, O; Chaney, J E; Digenis, G A

    1984-02-01

    This experiment was carried out in search for stimulators of the in vivo uptake of D- and L-leucine by tumor and pancreas for the possible application to gamma-emitter labeled amino acids in nuclear medical diagnosis. Inosine, uridine, and glutamine which are stimulators of the in vitro incorporation of radioactive L-amino acids into some tumor cells significantly enhanced the uptake of D-leucine into the pancreas, while in Ehrlich solid tumor only a little if any increase was observed. Of the compounds tested inosine showed the highest stimulation of pancreas uptake in the range of doses used, resulting in the best pancreas-to-liver concentration ratio, a factor of significant consideration for pancreas imaging. The uptake of L-leucine by the tumor and pancreas was little affected by these compounds. PMID:6739860

  6. Modulation of AgRP-neuronal function by SOCS3 as an initiating event in diet-induced hypothalamic leptin resistance

    PubMed Central

    Olofsson, Louise E.; Unger, Elizabeth K.; Cheung, Clement C.; Xu, Allison W.

    2013-01-01

    Chronic consumption of a fat-rich diet leads to attenuation of leptin signaling in hypothalamic neurons, a hallmark feature of cellular leptin resistance. To date, little is known about the temporal and spatial dysregulation of neuronal function under conditions of nutrient excess. We show that agouti-related protein (AgRP)-expressing neurons precede proopiomelanocortin neurons in developing diet-induced cellular leptin resistance. High-fat diet-induced up-regulation of suppressor of cytokine signaling-3 (SOCS3) occurs in AgRP neurons before proopiomelanocortin and other hypothalamic neurons. SOCS3 expression in AgRP neurons increases after 2 d of high-fat feeding, but reduces after switching to a low-fat diet for 1 d. Consistently, transgenic overexpression of SOCS3 in AgRP neurons produces metabolic phenotypes resembling those observed after short-term high-fat feeding. We further show that AgRP neurons are the predominant cell type situated outside the blood-brain barrier in the mediobasal hypothalamus. AgRP neurons are more responsive to low levels of circulating leptin, but they are also more prone to development of leptin resistance in response to a small increase in blood leptin concentrations. Collectively, these results suggest that AgRP neurons are able to sense slight changes in plasma metabolic signals, allowing them to serve as first-line responders to fluctuation of energy intake. Furthermore, modulation of SOCS3 expression in AgRP neurons may play a dynamic and physiological role in metabolic fine tuning in response to short-term changes of nutritional status. PMID:23386726

  7. The root knot nematode resistance gene Mi from tomato is a member of the leucine zipper, nucleotide binding, leucine-rich repeat family of plant genes.

    PubMed Central

    Milligan, S B; Bodeau, J; Yaghoobi, J; Kaloshian, I; Zabel, P; Williamson, V M

    1998-01-01

    The Mi locus of tomato confers resistance to root knot nematodes. Tomato DNA spanning the locus was isolated as bacterial artificial chromosome clones, and 52 kb of contiguous DNA was sequenced. Three open reading frames were identified with similarity to cloned plant disease resistance genes. Two of them, Mi-1.1 and Mi-1.2, appear to be intact genes; the third is a pseudogene. A 4-kb mRNA hybridizing with these genes is present in tomato roots. Complementation studies using cloned copies of Mi-1.1 and Mi-1.2 indicated that Mi-1.2, but not Mi-1.1, is sufficient to confer resistance to a susceptible tomato line with the progeny of transformants segregating for resistance. The cloned gene most similar to Mi-1.2 is Prf, a tomato gene required for resistance to Pseudomonas syringae. Prf and Mi-1.2 share several structural motifs, including a nucleotide binding site and a leucine-rich repeat region, that are characteristic of a family of plant proteins, including several that are required for resistance against viruses, bacteria, fungi, and now, nematodes. PMID:9707531

  8. Hypothalamic, rectal, and muscle temperatures in exercising dogs - Effect of cooling

    NASA Technical Reports Server (NTRS)

    Kruk, B.; Kaciuba-Uscilko, H.; Nazar, K.; Greenleaf, J. E.; Kozlowski, S.

    1985-01-01

    An experimental investigation of the mechanisms of performance prolongation during exercise is presented. Measurements were obtained of the rectal, muscle, and hypothalamic temperature of dogs during treadmill exercise at an ambient temperature of 22 + or - 1 C, with and without cooling by use of ice packs. In comparison with exercise without cooling, exercise with cooling was found to: (1) increase exercise duration from 90 + or - 14 to 145 + or - 15 min; (2) attenuate increases in hypothalamic, rectal and muscle temperature; (3) decrease respiratory and heart rates; and (4) lower blood lactic acid content. It is shown that although significant differences were found between the brain, core, and muscle temperatures during exercise with and without cooling, an inverse relation was observed between muscle temperature and the total duration of exercise. It is suggested that sustained muscle hyperthermia may have contributed to the limitation of working ability in exercise with and without cooling.

  9. The contribution of hypothalamic macroglia to the regulation of energy homeostasis

    PubMed Central

    Buckman, Laura B.; Ellacott, Kate L. J.

    2014-01-01

    The hypothalamus is critical for the regulation of energy homeostasis. Genetic and pharmacologic studies have identified a number of key hypothalamic neuronal circuits that integrate signals controlling food intake and energy expenditure. Recently, studies have begun to emerge demonstrating a role for non-neuronal cell types in the regulation of energy homeostasis. In particular the potential importance of different glial cell types is increasingly being recognized. A number of studies have described changes in the activity of hypothalamic macroglia (principally astrocytes and tanycytes) in response to states of positive and negative energy balance, such as obesity and fasting. This article will review these studies and discuss how these findings are changing our understanding of the cellular mechanisms by which energy homeostasis is regulated. PMID:25374514

  10. The impact of adipose tissue-derived factors on the hypothalamic-pituitary-gonadal (HPG) axis.

    PubMed

    Tsatsanis, Christos; Dermitzaki, Eirini; Avgoustinaki, Pavlina; Malliaraki, Niki; Mytaras, Vasilis; Margioris, Andrew N

    2015-01-01

    Adipose tissue produces factors, including adipokines, cytokines and chemokines which, when released, systemically exert endocrine effects on multiple tissues thereby affecting their physiology. Adipokines also affect the hypothalamic-pituitary-gonadal (HPG) axis both centrally, at the hypothalamic-pituitary level, and peripherally acting on the gonads themselves. Among the adipokines, leptin, adiponectin, resistin, chemerin and the peptide kisspeptin have pleiotropic actions on the HPG axis affecting male and female fertility. Furthermore, adipokines and adipose tissue-produced factors readily affect the immune system resulting in inflammation, which in turn impact the HPG axis, thus evidencing a link between metabolic inflammation and fertility. In this review we provide an overview of the existing extensive bibliography on the crosstalk between adipose tissue-derived factors and the HPG axis, with particular focus on the impact of obesity and the metabolic syndrome on gonadal function and fertility. PMID:26859602

  11. Effect of chronic D-fenfluramine administration on rat hypothalamic serotonin levels and release

    NASA Technical Reports Server (NTRS)

    Schaechter, Judith D.; Wurtman, Richard J.

    1989-01-01

    The effect of administering to rats (in doses of 1.25, 2.5, 5, or 10 mg/kg/day for 10 days) of an anorectic agent, D-fenfluramine, on the serotonin levels in hypothalamic tissue and on the in vitro release of serotonin by hypothalamic slices was investigated in rats which were sacrificed six days after the end of treatment. It was found that D-fenfuramine had no effect on tissue serotonin in doses from 1.25 to 5 mg/kg. However, given at 10 mg/kg level, serotonin led to a 22 percent decrease. The release of serotonin was found to be not affected by D-fenfluramine.

  12. Early life origins of metabolic disease: Developmental programming of hypothalamic pathways controlling energy homeostasis.

    PubMed

    Dearden, Laura; Ozanne, Susan E

    2015-10-01

    A wealth of animal and human studies demonstrate that perinatal exposure to adverse metabolic conditions - be it maternal obesity, diabetes or under-nutrition - results in predisposition of offspring to develop obesity later in life. This mechanism is a contributing factor to the exponential rise in obesity rates. Increased weight gain in offspring exposed to maternal obesity is usually associated with hyperphagia, implicating altered central regulation of energy homeostasis as an underlying cause. Perinatal development of the hypothalamus (a brain region key to metabolic regulation) is plastic and sensitive to metabolic signals during this critical time window. Recent research in non-human primate and rodent models has demonstrated that exposure to adverse maternal environments impairs the development of hypothalamic structure and consequently function, potentially underpinning metabolic phenotypes in later life. This review summarizes our current knowledge of how adverse perinatal environments program hypothalamic development and explores the mechanisms that could mediate these effects. PMID:26296796

  13. In situ hybridization of oxytocin messenger RNA: macroscopic distribution and quantitation in rat hypothalamic cell groups

    SciTech Connect

    Burbach, J.P.; Voorhuis, T.A.; van Tol, H.H.; Ivell, R.

    1987-05-29

    Oxytocin mRNA was detected in the rat hypothalamus by in situ hybridization to a single stranded /sup 35/S-labelled DNA probe and the distribution of oxytocin mRNA-containing cell groups was studied at the macroscopic level. Specificity of hybridization was confirmed by comparison to vasopressin mRNA hybridization in parallel tissue sections. Cell groups containing oxytocin mRNA were confined to a set of hypothalamic cell groups, i.c. the supraoptic, paraventricular, anterior commissural nuclei, nucleus circularis and scattered hypothalamic islets. These cell groups displayed similar densities of autoradiographic signals indicating that the oxytocin gene is expressed at approximately the same average level at these various sites.

  14. Glucose Regulates Hypothalamic Long-chain Fatty Acid Metabolism via AMP-activated Kinase (AMPK) in Neurons and Astrocytes*

    PubMed Central

    Taïb, Bouchra; Bouyakdan, Khalil; Hryhorczuk, Cécile; Rodaros, Demetra; Fulton, Stephanie; Alquier, Thierry

    2013-01-01

    Hypothalamic controls of energy balance rely on the detection of circulating nutrients such as glucose and long-chain fatty acids (LCFA) by the mediobasal hypothalamus (MBH). LCFA metabolism in the MBH plays a key role in the control of food intake and glucose homeostasis, yet it is not known if glucose regulates LCFA oxidation and esterification in the MBH and, if so, which hypothalamic cell type(s) and intracellular signaling mechanisms are involved. The aim of this study was to determine the impact of glucose on LCFA metabolism, assess the role of AMP-activated Kinase (AMPK), and to establish if changes in LCFA metabolism and its regulation by glucose vary as a function of the kind of LCFA, cell type, and brain region. We show that glucose inhibits palmitate oxidation via AMPK in hypothalamic neuronal cell lines, primary hypothalamic astrocyte cultures, and MBH slices ex vivo but not in cortical astrocytes and slice preparations. In contrast, oleate oxidation was not affected by glucose or AMPK inhibition in MBH slices. In addition, our results show that glucose increases palmitate, but not oleate, esterification into neutral lipids in neurons and MBH slices but not in hypothalamic astrocytes. These findings reveal for the first time the metabolic fate of different LCFA in the MBH, demonstrate AMPK-dependent glucose regulation of LCFA oxidation in both astrocytes and neurons, and establish metabolic coupling of glucose and LCFA as a distinguishing feature of hypothalamic nuclei critical for the control of energy balance. PMID:24240094

  15. HORIZON SENSING

    SciTech Connect

    Larry G. Stolarczyk, Sc.D.

    2002-07-31

    Real-time horizon sensing (HS) on continuous mining (CM) machines is becoming an industry tool. Installation and testing of production-grade HS systems has been ongoing this quarter at Oxbow Mining Company, Monterey Coal Company (EXXON), FMC Trona, Twentymile Coal Company (RAG America), and SASOL Coal. Detailed monitoring of system function, user experience, and mining benefits is ongoing. All horizon sensor components have finished MSHA (United States) and IEC (International) certification.

  16. Conversational sensing

    NASA Astrophysics Data System (ADS)

    Preece, Alun; Gwilliams, Chris; Parizas, Christos; Pizzocaro, Diego; Bakdash, Jonathan Z.; Braines, Dave

    2014-05-01

    Recent developments in sensing technologies, mobile devices and context-aware user interfaces have made it pos- sible to represent information fusion and situational awareness for Intelligence, Surveillance and Reconnaissance (ISR) activities as a conversational process among actors at or near the tactical edges of a network. Motivated by use cases in the domain of Company Intelligence Support Team (CoIST) tasks, this paper presents an approach to information collection, fusion and sense-making based on the use of natural language (NL) and controlled nat- ural language (CNL) to support richer forms of human-machine interaction. The approach uses a conversational protocol to facilitate a ow of collaborative messages from NL to CNL and back again in support of interactions such as: turning eyewitness reports from human observers into actionable information (from both soldier and civilian sources); fusing information from humans and physical sensors (with associated quality metadata); and assisting human analysts to make the best use of available sensing assets in an area of interest (governed by man- agement and security policies). CNL is used as a common formal knowledge representation for both machine and human agents to support reasoning, semantic information fusion and generation of rationale for inferences, in ways that remain transparent to human users. Examples are provided of various alternative styles for user feedback, including NL, CNL and graphical feedback. A pilot experiment with human subjects shows that a prototype conversational agent is able to gather usable CNL information from untrained human subjects.

  17. Mediobasal Hypothalamic SIRT1 Is Essential for Resveratrol’s Effects on Insulin Action in Rats

    PubMed Central

    Knight, Colette M.; Gutierrez-Juarez, Roger; Lam, Tony K.T.; Arrieta-Cruz, Isabel; Huang, Loli; Schwartz, Gary; Barzilai, Nir; Rossetti, Luciano

    2011-01-01

    OBJECTIVE Sirtuin 1 (SIRT1) and its activator resveratrol are emerging as major regulators of metabolic processes. We investigate the site of resveratrol action on glucose metabolism and the contribution of SIRT1 to these effects. Because the arcuate nucleus in the mediobasal hypothalamus (MBH) plays a pivotal role in integrating peripheral metabolic responses to nutrients and hormones, we examined whether the actions of resveratrol are mediated at the MBH. RESEARCH DESIGN AND METHODS Sprague Dawley (SD) male rats received acute central (MBH) or systemic injections of vehicle, resveratrol, or SIRT1 inhibitor during basal pancreatic insulin clamp studies. To delineate the pathway(s) by which MBH resveratrol modulates hepatic glucose production, we silenced hypothalamic SIRT1 expression using a short hairpin RNA (shRNA) inhibited the hypothalamic ATP-sensitive potassium (KATP) channel with glibenclamide, or selectively transected the hepatic branch of the vagus nerve while infusing resveratrol centrally. RESULTS Our studies show that marked improvement in insulin sensitivity can be elicited by acute administration of resveratrol to the MBH or during acute systemic administration. Selective inhibition of hypothalamic SIRT1 using a cell-permeable SIRT1 inhibitor or SIRT1-shRNA negated the effect of central and peripheral resveratrol on glucose production. Blockade of the KATP channel and hepatic vagotomy significantly attenuated the effect of central resveratrol on hepatic glucose production. In addition, we found no evidence for hypothalamic AMPK activation after MBH resveratrol administration. CONCLUSIONS Taken together, these studies demonstrate that resveratrol improves glucose homeostasis mainly through a central SIRT1-dependent pathway and that the MBH is a major site of resveratrol action. PMID:21896928

  18. Neuromedin B stimulates the hypothalamic-pituitary-gonadal axis in male rats.

    PubMed

    Boughton, C K; Patel, S A; Thompson, E L; Patterson, M; Curtis, A E; Amin, A; Chen, K; Ghatei, M A; Bloom, S R; Murphy, K G

    2013-11-10

    Neuromedin B (NMB) is a highly conserved bombesin-related peptide found in mammals. NMB mRNA is detected in the central nervous system (CNS) and is highly expressed in the rat hypothalamus, in particular the medial preoptic area and the arcuate nucleus. The mammalian bombesin family of receptors consists of three closely related G protein coupled receptors, BB1, BB2 and BB3. The BB1 receptor subtype has the highest affinity for NMB. NMB has well documented roles in the regulation of the thyroid axis and the stress axis in rats. However, there is little available data regarding the role of NMB in the regulation of the hypothalamic-pituitary-gonadal (HPG) axis. It is known that the NMB receptor is expressed in immortalised gonadotrophin releasing hormone (GnRH) releasing GT1-7 cells and murine forebrain GnRH neurons, and that anterior pituitary NMB-immunoreactivity is altered by changes in the sex steroid environment. The objective of these studies was thus to further investigate the effects of NMB on the HPG axis. Intracerebroventricular (ICV) administration of NMB (10 nmol) to adult male rats significantly increased plasma luteinising hormone (LH) levels 30 min after injection (plasma LH ng/ml; saline 0.69±0.07, 10 nmol NMB 1.33±0.17, P<0.01). In vitro, NMB stimulated GnRH release from hypothalamic explants from male rats and from hypothalamic GT1-7 cells. NMB had no significant effect on LH release from anterior pituitary explants from male rats, or from pituitary LβT2 cells in vitro. These results suggest a previously unreported role for NMB in the stimulation of the HPG axis via hypothalamic GnRH. Further work is now required to determine the receptor mediating the effects of NMB on the reproductive axis and the physiological role of NMB in reproduction. PMID:24120470

  19. Impact of hypothalamic reactive oxygen species in the regulation of energy metabolism and food intake

    PubMed Central

    Drougard, Anne; Fournel, Audren; Valet, Philippe; Knauf, Claude

    2015-01-01

    Hypothalamus is a key area involved in the control of metabolism and food intake via the integrations of numerous signals (hormones, neurotransmitters, metabolites) from various origins. These factors modify hypothalamic neurons activity and generate adequate molecular and behavioral responses to control energy balance. In this complex integrative system, a new concept has been developed in recent years, that includes reactive oxygen species (ROS) as a critical player in energy balance. ROS are known to act in many signaling pathways in different peripheral organs, but also in hypothalamus where they regulate food intake and metabolism by acting on different types of neurons, including proopiomelanocortin (POMC) and agouti-related protein (AgRP)/neuropeptide Y (NPY) neurons. Hypothalamic ROS release is under the influence of different factors such as pancreatic and gut hormones, adipokines (leptin, apelin,…), neurotransmitters and nutrients (glucose, lipids,…). The sources of ROS production are multiple including NADPH oxidase, but also the mitochondria which is considered as the main ROS producer in the brain. ROS are considered as signaling molecules, but conversely impairment of this neuronal signaling ROS pathway contributes to alterations of autonomic nervous system and neuroendocrine function, leading to metabolic diseases such as obesity and type 2 diabetes. In this review we focus our attention on factors that are able to modulate hypothalamic ROS release in order to control food intake and energy metabolism, and whose deregulations could participate to the development of pathological conditions. This novel insight reveals an original mechanism in the hypothalamus that controls energy balance and identify hypothalamic ROS signaling as a potential therapeutic strategy to treat metabolic disorders. PMID:25759638

  20. Familial cerebellar ataxia and hypogonadotropic hypogonadism: evidence for hypothalamic LHRH deficiency.

    PubMed Central

    Berciano, J; Amado, J A; Freijanes, J; Rebollo, M; Vaquero, A

    1982-01-01

    A family with familial cerebellar ataxia and hypogonadotropic hypogonadism is described. The condition was inherited as an autosomal recessive defect. CT scan in one case revealed cerebellar and brain stem atrophy. Endocrinological tests showed abnormalities only in two patients who were clinically affected. In both cases raised gonadotropic levels were found after repetitive stimulation with luteining hormone-releasing hormone which suggests that the hypogonadism was due to a primary hypothalamic disturbance. Images PMID:6813427

  1. Success, failure, and putative mechanisms in hypothalamic stimulation for drug-resistant chronic cluster headache.

    PubMed

    Leone, Massimo; Franzini, Angelo; Proietti Cecchini, Alberto; Bussone, Gennaro

    2013-01-01

    Drug-resistant chronic cluster headache (CH) is an unremitting illness with excruciatingly severe headaches that occur several times daily. Starting in 2000, a total of 19 patients with long-lasting chronic CH, with multiple daily attacks unresponsive to all known prophylactics, received stimulation of the posterior inferior hypothalamic area ipsilateral to the pain as treatment. We report long-term follow-up (median 8.7 years, range 6-12 years) in 17 patients. Long-lasting improvement occurred in 70% (12 of 17): 6 are persistently almost pain-free; another 6 no longer experience daily attacks but rather episodic CH interspersed with long-lasting remissions. In 5 of 6 almost pain-free patients, the stimulators have been off for a median of 3 years (range 3-4 years). Five patients did not improve: 4 had bilateral CH, and 3 developed tolerance after experiencing relief for 1-2 years. Adverse events are electrode displacement (n=2), infection (electrode n=3; generator n=1), electrode malpositioning (n=1), transient nonsymptomatic third ventricle hemorrhage (n=1), persistent slight muscle weakness on one side (n=1), and seizure (n=1). This exceptionally long follow-up shows that hypothalamic stimulation for intractable chronic CH produces long-lasting improvement in many patients. Previous experience was limited to a median of 16 months. Important new findings are as follows: stimulation is well tolerated for many years after implantation; after several years during which stimulation was necessary for relief, a persistent almost pain-free condition can be maintained when stimulation is off, suggesting that hypothalamic stimulation can change disease course; tolerance can occur after marked long-lasting improvement; and bilateral chronic CH seems to predict poor response to hypothalamic stimulation. PMID:23103434

  2. Water deprivation-partial rehydration induces sensitization of sodium appetite and alteration of hypothalamic transcripts.

    PubMed

    Pereira-Derderian, Daniela T B; Vendramini, Regina C; Menani, José V; Chiavegatto, Silvana; De Luca, Laurival A

    2016-01-01

    iSodium intake occurs either as a spontaneous or induced behavior, which is enhanced, i.e., sensitized, by repeated episodes of water deprivation followed by subsequent partial rehydration (WD-PR). In the present work, we examined whether repeated WD-PR alters hypothalamic transcripts related to the brain renin-angiotensin system (RAS) and apelin system in male normotensive Holtzman rats (HTZ). We also examined whether the sodium intake of a strain with genetically inherited high expression of the brain RAS, the spontaneously hypertensive rat (SHR), responds differently than HTZ to repeated WD-PR. We found that repeated WD-PR, besides enhancing spontaneous and induced 0.3 M NaCl intake, increased the hypothalamic expression of angiotensinogen, aminopeptidase N, and apelin receptor transcripts (43%, 60%, and 159%, respectively) in HTZ at the end of the third WD-PR. Repeated WD-PR did not change the daily spontaneous 0.3 M NaCl intake and barely changed the need-induced 0.3 M NaCl intake of SHR. The same treatment consistently enhanced spontaneous daily 0.3 M NaCl intake in the normotensive Wistar-Kyoto rats. The results show that repeated WD-PR produces alterations in hypothalamic transcripts and also sensitizes sodium appetite in HTZ. They suggest an association between the components of hypothalamic RAS and the apelin system, with neural and behavioral plasticity produced by repeated episodes of WD-PR in a normotensive strain. The results also indicate that the inherited hyperactive brain RAS is not a guarantee for sensitization of sodium intake in the male adult SHR exposed to repeated WD-PR. PMID:26538239

  3. The improvement of exercise performance by physical training is related to increased hypothalamic neuronal activation.

    PubMed

    Santiago, Henrique P; Leite, Laura H R; Lima, Paulo Marcelo A; Rodovalho, Gisele V; Szawka, Raphael E; Coimbra, Cândido C

    2016-01-01

    The effects of physical training on hypothalamic activation after exercise and their relationship with heat dissipation were investigated. Following 8 weeks of physical training, trained (TR, n = 9) and untrained (UN, n = 8) Wistar rats were submitted to a regimen of incremental running until fatigue while body and tail temperatures were recorded. After exercise, hypothalamic c-Fos immunohistochemistry analysis was performed. The workload, body-heating rate, heat storage and body temperature threshold for cutaneous vasodilation were calculated. Physical training increased the number of c-Fos immunoreactive neurons in the paraventricular, medial preoptic and median preoptic nucleus by 112%, 90% and 65% (P < 0.01) after exercise, respectively. In these hypothalamic regions, increased neuronal activation was directly associated with the increased workload performed by TR animals (P < 0.01). Moreover, a reduction of 0.6°C in the body temperature threshold for cutaneous vasodilation was shown by TR animals (P < 0.01). This reduction was possibly responsible for the lower body-heating rate (0.019 ± 0.002°C/min, TR vs 0.030 ± 0.005°C/min, UN, P < 0.05) and the decreased ratio between heat storage and the workload performed by TR animals (18.18 ± 1.65 cal/kg, TR vs 31.38 ± 5.35 cal/kg, UN, P < 0.05). The data indicate that physical training enhances hypothalamic neuronal activation during exercise. This enhancement is the central adaptation relating to better physical performance, characterized by a lower ratio of heat stored to workload performed, due to improved heat dissipation. PMID:26475529

  4. Hypothalamic CaMKKβ mediates glucagon anorectic effect and its diet-induced resistance

    PubMed Central

    Quiñones, Mar; Al-Massadi, Omar; Gallego, Rosalía; Fernø, Johan; Diéguez, Carlos; López, Miguel; Nogueiras, Ruben

    2015-01-01

    Objective Glucagon receptor antagonists and humanized glucagon antibodies are currently studied as promising therapies for obesity and type II diabetes. Among its variety of actions, glucagon reduces food intake, but the molecular mechanisms mediating this effect as well as glucagon resistance are totally unknown. Methods Glucagon and adenoviral vectors were administered in specific hypothalamic nuclei of lean and diet-induced obese rats. The expression of neuropeptides controlling food intake was performed by in situ hybridization. The regulation of factors of the glucagon signaling pathway was assessed by western blot. Results The central injection of glucagon decreased feeding through a hypothalamic pathway involving protein kinase A (PKA)/Ca2+-calmodulin-dependent protein kinase kinase β (CaMKKβ)/AMP-activated protein kinase (AMPK)-dependent mechanism. More specifically, the central injection of glucagon increases PKA activity and reduces protein levels of CaMKKβ and its downstream target phosphorylated AMPK in the hypothalamic arcuate nucleus (ARC). Consistently, central glucagon significantly decreased AgRP expression. Inhibition of PKA and genetic activation of AMPK in the ARC blocked glucagon-induced anorexia in lean rats. Genetic down-regulation of glucagon receptors in the ARC stimulates fasting-induced hyperphagia. Although glucagon was unable to decrease food intake in DIO rats, glucagon sensitivity was restored after inactivation of CaMKKβ, specifically in the ARC. Thus, glucagon decreases food intake acutely via PKA/CaMKKβ/AMPK dependent pathways in the ARC, and CaMKKβ mediates its obesity-induced hypothalamic resistance. Conclusions This work reveals the molecular underpinnings by which glucagon controls feeding that may lead to a better understanding of disease states linked to anorexia and cachexia. PMID:26909312

  5. Mediobasal hypothalamic and adenohypophyseal TRH-degrading enzyme (PPII) is down-regulated by zinc deficiency.

    PubMed

    Alvarez-Salas, Elena; Alcántara-Alonso, Viridiana; Matamoros-Trejo, Gilberto; Vargas, Miguel Angel; Morales-Mulia, Marcela; de Gortari, Patricia

    2015-11-01

    Thyrotropin-releasing hormone (TRH) synthesized in hypothalamic paraventricular nucleus directs hypothalamus-pituitary-thyroid (HPT) axis function, regulating thyrotropin release from adenohypophysis and thyroid hormones serum concentration. Pyroglutamyl aminopeptidase II (PPII), a Zn-dependent metallopeptidase located in adenohypophysis and medial-basal-hypothalamus degrades TRH released from the median eminence and participates in HPT axis function by regulating TRH-induced thyrotropin release from adenohypophysis. It is unknown whether dietary Zn deficiency down-regulates PPII. Our aim was to compare adenohypohyseal and medial-basal-hypothalamic PPII activity and expression of adult rats fed a Zn-deficient diet (2ppm) throughout their lifespan (DD), prenatally (DC) or after weaning (CD) vs. that of animals fed a control diet (20ppm:CC). Female rats consumed a Zn-deficient or control diet from two weeks before gestation and up to the end of lactation. We analyzed adenohypophyseal and medial-basal-hypothalamic PPII activity of dams and male offspring when adults; its relation to median eminence TRH, serum thyrotropin, leptin and thyroid hormones concentration. Offspring ate the same diet as their dams (CC, DD) or were switched from dietary regime after weaning (CD, DC) and until 2.5 months of age. DD males showed decreased adenohypophyseal and medial-basal-hypothalamic PPII activity, along with high thyrotropin serum concentration. Post-weaning Zn-deficiency (CD) decreased PPII activity only in adenohypophysis and increased thyrotropin circulating levels. Zn-replenishment (DC) normalized PPII activity in both regions and serum thyrotropin concentration. Adenohypophyseal PPII activity decreased and prolactin levels increased in Zn-deficient dams. We concluded that long-term changes in dietary Zn down-regulate PPII activity independently of T3, increasing thyrotropin serum concentration, overall resembling sub-clinical hypothyroidism. PMID:26315400

  6. Correlation of the Hippocampal theta rhythm to changes in hypothalamic temperature

    NASA Technical Reports Server (NTRS)

    Saleh, M. A.; Horowitz, J. M.; Hsieh, A. C. L.

    1974-01-01

    Warming and cooling the preoptic anterior hypothalamic area in awake, loosely restrained rabbits was found to evoke theta rhythm. This is consistent with previous studies indicating that theta rhythm is a nonspecific response evoked by stimulation of several sensory modalities. Several studies have correlated theta rhythm with alertness. A neural pathway involving the hypothalamus, the hippocampus, the septal area, and the reticular formation is proposed. Thus, a role of this pathway may be to alert the animal to changes in its body temperature.

  7. Hypothalamic Prolactin Regulation of Luteinizing Hormone Secretion in the Female Rat.

    PubMed

    Grachev, Pasha; Li, Xiao Feng; Goffin, Vincent; O'Byrne, Kevin T

    2015-08-01

    Prolactin (PRL) levels increase in response to long-term antipsychotic treatment that disrupts reproductive function. Recent evidence suggests that activation of central PRL receptors (PRLR) inhibits LH secretion and in ovariectomized rats. However, the mechanisms involved, the mode of LH secretion affected and relevance to hyperprolactinemia remain unknown. We therefore investigated the contribution of central PRL/PRLR signaling to the control of estradiol-induced surges of LH and PRL and pulsatile LH secretion under basal and hyperprolactinemic conditions. First, by subjecting ovariectomized estradiol-primed rats intracerebroventricularly administered with PRL to frequent blood sampling, we demonstrated that acute activation of hypothalamic PRLR disrupts pulsatile LH secretion. Pretreatment (intracerebroventricularly) with the pure PRLR antagonist, Δ1-9-G129R-hPRL, or the γ-aminobutyric acid receptor type A antagonist, bicuculline, blocked this effect. Next, we revealed that sustained blockade of hypothalamic PRLR using Δ1-9-G129R-hPRL augmented the magnitude of LH surges induced by estradiol benzoate and progesterone treatment and suppressed the concomitant surges of PRL. Finally, we determined that acute antagonism of central PRLR is insufficient to normalize the duration of the LH pulse interval prolonged as a result of hyperprolactinemia induced by chronic exposure to the atypical antipsychotic sulpiride. These data serve as the first evidence to suggest that PRL signaling through hypothalamic PRLR inhibits pulsatile secretion of LH in a γ-aminobutyric acid receptor type A-dependent fashion and tonically restrains the magnitude of the LH surge. Furthermore, our results indicate that transient blockade of hypothalamic PRL/PRLR signaling is not an effective strategy for restoring LH pulsatility perturbed by chronic hyperprolactinemia. PMID:25993525

  8. The LIM Homeodomain Factor Lhx2 Is Required for Hypothalamic Tanycyte Specification and Differentiation

    PubMed Central

    Salvatierra, Juan; Lee, Daniel A.; Zibetti, Cristina; Duran-Moreno, Maria; Yoo, Sooyeon; Newman, Elizabeth A.; Wang, Hong; Bedont, Joseph L.; de Melo, Jimmy; Miranda-Angulo, Ana L.; Gil-Perotin, Sara; Garcia-Verdugo, Jose Manuel

    2014-01-01

    Hypothalamic tanycytes, a radial glial-like ependymal cell population that expresses numerous genes selectively enriched in embryonic hypothalamic progenitors and adult neural stem cells, have recently been observed to serve as a source of adult-born neurons in the mammalian brain. The genetic mechanisms that regulate the specification and maintenance of tanycyte identity are unknown, but are critical for understanding how these cells can act as adult neural progenitor cells. We observe that LIM (Lin-11, Isl-1, Mec-3)-homeodomain gene Lhx2 is selectively expressed in hypothalamic progenitor cells and tanycytes. To test the function of Lhx2 in tanycyte development, we used an intersectional genetic strategy to conditionally delete Lhx2 in posteroventral hypothalamic neuroepithelium, both embryonically and postnatally. We observed that tanycyte development was severely disrupted when Lhx2 function was ablated during embryonic development. Lhx2-deficient tanycytes lost expression of tanycyte-specific genes, such as Rax, while also displaying ectopic expression of genes specific to cuboid ependymal cells, such as Rarres2. Ultrastructural analysis revealed that mutant tanycytes exhibited a hybrid identity, retaining radial morphology while becoming multiciliated. In contrast, postnatal loss of function of Lhx2 resulted only in loss of expression of tanycyte-specific genes. Using chromatin immunoprecipitation, we further showed that Lhx2 directly regulated expression of Rax, an essential homeodomain factor for tanycyte development. This study identifies Lhx2 as a key intrinsic regulator of tanycyte differentiation, sustaining Rax-dependent activation of tanycyte-specific genes while also inhibiting expression of ependymal cell-specific genes. These findings provide key insights into the transcriptional regulatory network specifying this still poorly characterized cell type. PMID:25505333

  9. Connections of the juxtaventromedial region of the lateral hypothalamic area in the male rat

    PubMed Central

    Hahn, Joel D.; Swanson, Larry W.

    2015-01-01

    Evolutionary conservation of the hypothalamus attests to its critical role in the control of fundamental behaviors. However, our knowledge of hypothalamic connections is incomplete, particularly for the lateral hypothalamic area (LHA). Here we present the results of neuronal pathway-tracing experiments to investigate connections of the LHA juxtaventromedial region, which is parceled into dorsal (LHAjvd) and ventral (LHAjvv) zones. Phaseolus vulgaris leucoagglutinin (PHAL, for outputs) and cholera toxin B subunit (CTB, for inputs) coinjections were targeted stereotaxically to the LHAjvd/v. Results: LHAjvd/v connections overlapped highly but not uniformly. Major joint outputs included: Bed nuc. stria terminalis (BST), interfascicular nuc. (BSTif) and BST anteromedial area, rostral lateral septal (LSr)- and ventromedial hypothalamic (VMH) nuc., and periaqueductal gray. Prominent joint LHAjvd/v input sources included: BSTif, BST principal nuc., LSr, VMH, anterior hypothalamic-, ventral premammillary-, and medial amygdalar nuc., and hippocampal formation (HPF) field CA1. However, LHAjvd HPF retrograde labeling was markedly more abundant than from the LHAjvv; in the LSr this was reversed. Furthermore, robust LHAjvv (but not LHAjvd) targets included posterior- and basomedial amygdalar nuc., whereas the midbrain reticular nuc. received a dense input from the LHAjvd alone. Our analyses indicate the existence of about 500 LHAjvd and LHAjvv connections with about 200 distinct regions of the cerebral cortex, cerebral nuclei, and cerebrospinal trunk. Several highly LHAjvd/v-connected regions have a prominent role in reproductive behavior. These findings contrast with those from our previous pathway-tracing studies of other LHA medial and perifornical tier regions, with different connectional behavioral relations. The emerging picture is of a highly differentiated LHA with extensive and far-reaching connections that point to a role as a central coordinator of behavioral control

  10. The effects of hypothalamic temperature variation and intracarotid cooling on behavioural thermoregulation in sheep.

    PubMed Central

    Baldwin, B A; Yates, J O

    1977-01-01

    1. Shorn-sheep, placed in cold environments, have been trained to turn on infra-red heaters. The effect, on this thermoregulatory behaviour, of warming and cooling the hypothalamus by means of a thermode has been examined. 2. At ambient temperatures of 5, 15, 25 and 35 degrees C; cooling the anterior hypothalamus by means of a thermode, for periods of 20 min, resulted in a marked increase in the rate of using the heaters. 3. At ambient temperatures of 5 and 15 degrees C, warming the anterior hypothalamus for periods of 20 min caused a considerable reduction in the rate of using the radiant heaters. 4. At an ambient temperature of 10 degrees C, a 2 hr period of hypothalamic cooling resulted in an increase in the rate at which the heaters were used for the first 70 min, but after this the effect was reduced and the reduction coincided with a rise of deep body temperature of about 0-75 degress C. 5. At an ambient temperature of 10 degress C, a 2 hr period of hypothalamic warming resulted in a reduction in the rate of operating the heaters during the first 85 min, but after this period the use of the heaters increased and this increase coincided with a fall of about 0-75 degrees C in deep body temperature. 6. At ambient temperatures of 15, 25 and 35 degrees C, the cephalic region was cooled by intracarotid injections of cold saline for periods of 15 min. This procedure lowered hypothalamic temperature by about 1 degree C and produced increases in the rate at which the heaters were used similar to those seen when the thermode was cooled. To elicit marked increases in the rate at which the heaters were used it was not necessary to lower hypothalamic temperature outside the normal range. PMID:856988

  11. Ancient views on the hypothalamic-pituitary-thyroid axis: an historical and epistemological perspective.

    PubMed

    Toni, R

    2000-10-01

    The modern views on the anatomical and physiological interactions between the hypothalamus, pituitary and thyroid gland have emerged only in the last fifty years, although their historical roots may be found in a number of ancient and still not widely known ideas and observations. The regulation of energy body stores and temperature by the hypothalamic-pituitary-thyroid axis, for example, is a classical case of "fixitè du mileu interieur" in the sense originally suggested by Claude Bernard in the late 1800s, i.e. a homeostatic mechanism, but already 2100 year previously Aristotle had stated that the brain was necessary for the maintenance of body integrity by regulating food intake and behavior in relation to body temperature, the latter primarily determined by the heat of the blood. Five hundred years later Galen of Pergamon reported fundamental discoveries in the anatomy of the third ventricle region, including the location of the pituitary gland inside the sella turcica embodied in a vascular network, the rete mirabilis, and observed nerves adjoining the "soft flesh" in the neck, i.e. the thyroid gland. He first proposed that the energy of the body (the vital spirit) was carried through the arteries at the level of the rete mirabilis, where it was transformed into nerve impulse (the animal spirit), eventually transferred by the nerves to the periphery of the body, "glands" included, raising implicitly the possibility for a nervous influence over the thyroid activity. The Galenic model remained virtually unaltered up to the beginning of the 14th century, when the mediaeval anatomist Mondino de' Liuzzi put forth the idea that the thyroid gland interacted with the heat of the blood present in the internal carotid arteries due to their anatomical relation with the thyroid. This interaction enriched the vital spirit, i.e. the energy of the body, prior to its transformation into animal spirit, i.e. to nerve impulse directed to the periphery of the body. In addition

  12. Physiological and pathophysiological implications of lipid sensing in the brain.

    PubMed

    Picard, A; Moullé, V S; Le Foll, C; Cansell, C; Véret, J; Coant, N; Le Stunff, H; Migrenne, S; Luquet, S; Cruciani-Guglielmacci, C; Levin, B E; Magnan, C

    2014-09-01

    Fatty acid (FA)-sensitive neurons are present in the brain, especially the hypothalamus, and play a key role in the neural control of energy homeostasis. Through neuronal output, FA may modulate feeding behaviour as well as insulin secretion and action. Subpopulations of neurons in the ventromedial and arcuate hypothalamic nuclei are selectively either inhibited or activated by FA. Molecular effectors of these FA effects probably include chloride or potassium ion channels. While intracellular metabolism and activation of the ATP-sensitive K⁺ channel appear to be necessary for some of the signalling effects of FA, at least half of the FA responses in ventromedial hypothalamic neurons are mediated by interaction with FAT/CD36, an FA transporter/receptor that does not require intracellular metabolism to activate downstream signalling. Thus, FA or their metabolites can modulate neuronal activity as a means of directly monitoring ongoing fuel availability by brain nutrient-sensing neurons involved in the regulation of energy and glucose homeostasis. Recently, the role of lipoprotein lipase in FA sensing has also been shown in animal models not only in hypothalamus, but also in hippocampus and striatum. Finally, FA overload might impair neural control of energy homeostasis through enhanced ceramide synthesis and may contribute to obesity and/or type 2 diabetes pathogenesis in predisposed subjects. PMID:25200296

  13. Hypothalamic AMPK: a canonical regulator of whole-body energy balance.

    PubMed

    López, Miguel; Nogueiras, Rubén; Tena-Sempere, Manuel; Diéguez, Carlos

    2016-07-01

    AMP-activated protein kinase (AMPK) has a major role in the modulation of energy balance. AMPK is activated in conditions of low energy, increasing energy production and reducing energy consumption. The AMPK pathway is a canonical route regulating energy homeostasis by integrating peripheral signals, such as hormones and metabolites, with neuronal networks. Current evidence has implicated AMPK in the hypothalamus and hindbrain with feeding, brown adipose tissue thermogenesis and browning of white adipose tissue, through modulation of the sympathetic nervous system, as well as glucose homeostasis. Interestingly, several potential antiobesity and/or antidiabetic agents, some of which are currently in clinical use such as metformin and liraglutide, exert some of their actions by acting on AMPK. Furthermore, the orexigenic and weight-gain effects of commonly used antipsychotic drugs are also mediated by hypothalamic AMPK. Overall, this evidence suggests that hypothalamic AMPK signalling is an interesting target for drug development, but is this approach feasible? In this Review we discuss the current understanding of hypothalamic AMPK and its role in the central regulation of energy balance and metabolism. PMID:27199291

  14. Developmental programming of hypothalamic neuronal circuits: impact on energy balance control.

    PubMed

    Gali Ramamoorthy, Thanuja; Begum, Ghazala; Harno, Erika; White, Anne

    2015-01-01

    The prevalence of obesity in adults and children has increased globally at an alarming rate. Mounting evidence from both epidemiological studies and animal models indicates that adult obesity and associated metabolic disorders can be programmed by intrauterine and early postnatal environment- a phenomenon known as "fetal programming of adult disease." Data from nutritional intervention studies in animals including maternal under- and over-nutrition support the developmental origins of obesity and metabolic syndrome. The hypothalamic neuronal circuits located in the arcuate nucleus controlling appetite and energy expenditure are set early in life and are perturbed by maternal nutritional insults. In this review, we focus on the effects of maternal nutrition in programming permanent changes in these hypothalamic circuits, with experimental evidence from animal models of maternal under- and over-nutrition. We discuss the epigenetic modifications which regulate hypothalamic gene expression as potential molecular mechanisms linking maternal diet during pregnancy to the offspring's risk of obesity at a later age. Understanding these mechanisms in key metabolic genes may provide insights into the development of preventative intervention strategies. PMID:25954145

  15. Inhibition of hypothalamic Foxo1 expression reduced food intake in diet-induced obesity rats

    PubMed Central

    Ropelle, Eduardo R; Pauli, José R; Prada, Patrícia; Cintra, Dennys E; Rocha, Guilherme Z; Moraes, Juliana C; Frederico, Marisa J S; da Luz, Gabrielle; Pinho, Ricardo A; Carvalheira, José B C; Velloso, Licio A; Saad, Mario A; De Souza, Cláudio T

    2009-01-01

    Insulin signalling in the hypothalamus plays a role in maintaining body weight. The forkhead transcription factor Foxo1 is an important mediator of insulin signalling in the hypothalamus. Foxo1 stimulates the transcription of the orexigenic neuropeptide Y and Agouti-related protein through the phosphatidylinositol-3-kinase/Akt signalling pathway, but the role of hypothalamic Foxo1 in insulin resistance and obesity remains unclear. Here, we identify that a high-fat diet impaired insulin-induced hypothalamic Foxo1 phosphorylation and degradation, increasing the nuclear Foxo1 activity and hyperphagic response in rats. Thus, we investigated the effects of the intracerebroventricular (i.c.v.) microinfusion of Foxo1-antisense oligonucleotide (Foxo1-ASO) and evaluated the food consumption and weight gain in normal and diet-induced obese (DIO) rats. Three days of Foxo1-ASO microinfusion reduced the hypothalamic Foxo1 expression by about 85%. i.c.v. infusion of Foxo1-ASO reduced the cumulative food intake (21%), body weight change (28%), epididymal fat pad weight (22%) and fasting serum insulin levels (19%) and increased the insulin sensitivity (34%) in DIO but not in control animals. Collectively, these data showed that the Foxo1-ASO treatment blocked the orexigenic effects of Foxo1 and prevented the hyperphagic response in obese rats. Thus, pharmacological manipulation of Foxo1 may be used to prevent or treat obesity. PMID:19332486

  16. Hypothalamic metabolic compartmentation during appetite regulation as revealed by magnetic resonance imaging and spectroscopy methods

    PubMed Central

    Lizarbe, Blanca; Benitez, Ania; Peláez Brioso, Gerardo A.; Sánchez-Montañés, Manuel; López-Larrubia, Pilar; Ballesteros, Paloma; Cerdán, Sebastián

    2013-01-01

    We review the role of neuroglial compartmentation and transcellular neurotransmitter cycling during hypothalamic appetite regulation as detected by Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS) methods. We address first the neurochemical basis of neuroendocrine regulation in the hypothalamus and the orexigenic and anorexigenic feed-back loops that control appetite. Then we examine the main MRI and MRS strategies that have been used to investigate appetite regulation. Manganese-enhanced magnetic resonance imaging (MEMRI), Blood oxygenation level-dependent contrast (BOLD), and Diffusion-weighted magnetic resonance imaging (DWI) have revealed Mn2+ accumulations, augmented oxygen consumptions, and astrocytic swelling in the hypothalamus under fasting conditions, respectively. High field 1H magnetic resonance in vivo, showed increased hypothalamic myo-inositol concentrations as compared to other cerebral structures. 1H and 13C high resolution magic angle spinning (HRMAS) revealed increased neuroglial oxidative and glycolytic metabolism, as well as increased hypothalamic glutamatergic and GABAergic neurotransmissions under orexigenic stimulation. We propose here an integrative interpretation of all these findings suggesting that the neuroendocrine regulation of appetite is supported by important ionic and metabolic transcellular fluxes which begin at the tripartite orexigenic clefts and become extended spatially in the hypothalamus through astrocytic networks becoming eventually MRI and MRS detectable. PMID:23781199

  17. Norepinephrine release and reuptake by hypothalamic synaptosomes of spontaneously hypertensive rats

    SciTech Connect

    Hano, T.; Jeng, Y.; Rho, J.

    1989-03-01

    We compared the overflow of endogenous norepinephrine during electrical field stimulation, the norepinephrine content, and the rate of initial neuronal uptake of (3H)norepinephrine in synaptosomes isolated from hypothalamus and brainstem of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats at 7 and 13 weeks of age. The synaptosomes of two rats, a SHR and a WKY rat control, were simultaneously processed and subjected to the same electrical field stimulation. The overflow of endogenous norepinephrine during electrical stimulation (2 Hz, 2 minutes) in the hypothalamic synaptosomes of 7-week-old SHR was significantly greater, whereas the overflow of 13-week-old SHR was equivalent to the age-matched WKY rat. The norepinephrine content of synaptosomes was about the same in SHR and age-matched controls. There was also significantly enhanced (3H)norepinephrine uptake in the hypothalamic synaptosomes of young SHR, but neither the hypothalamic nor the brainstem samples of 13-week-old SHR showed any significant difference in their rate of (3H)norepinephrine uptake. These data are similar to those we observed (unpublished observations) in perfused mesenteric artery system in which norepinephrine release was significantly elevated during periarterial nerve stimulation only in young SHR. Thus, these results suggest that a parallel enhancement of norepinephrine release in hypothalamus with that of peripheral nervous system may play an important role during development of hypertension in young SHR.

  18. Neuroanatomical association of hypothalamic HSD2-containing neurons with ERα, catecholamines, or oxytocin: implications for feeding?

    PubMed Central

    Askew, Maegan L.; Muckelrath, Halie D.; Johnston, Jonathon R.; Curtis, Kathleen S.

    2015-01-01

    This study used immunohistochemical methods to investigate the possibility that hypothalamic neurons that contain 11-β-hydroxysteroid dehydrogenase type 2 (HSD2) are involved in the control of feeding by rats via neuroanatomical associations with the α subtype of estrogen receptor (ERα), catecholamines, and/or oxytocin (OT). An aggregate of HSD2-containing neurons is located laterally in the hypothalamus, and the numbers of these neurons were greatly increased by estradiol treatment in ovariectomized (OVX) rats compared to numbers in male rats and in OVX rats that were not given estradiol. However, HSD2-containing neurons were anatomically segregated from ERα-containing neurons in the Ventromedial Hypothalamus and the Arcuate Nucleus. There was an absence of OT-immunolabeled fibers in the area of HSD2-labeled neurons. Taken together, these findings provide no support for direct associations between hypothalamic HSD2 and ERα or OT neurons in the control of feeding. In contrast, there was catecholamine-fiber labeling in the area of HSD2-labeled neurons, and these fibers occasionally were in close apposition to HSD2-labeled neurons. Therefore, we cannot rule out interactions between HSD2 and catecholamines in the control of feeding; however, given the relative sparseness of the appositions, any such interaction would appear to be modest. Thus, these studies do not conclusively identify a neuroanatomical substrate by which HSD2-containing neurons in the hypothalamus may alter feeding, and leave the functional role of hypothalamic HSD2-containing neurons subject to further investigation. PMID:26124709

  19. A sexually dimorphic hypothalamic response to chronic high-fat diet consumption.

    PubMed

    Morselli, E; Frank, A P; Palmer, B F; Rodriguez-Navas, C; Criollo, A; Clegg, D J

    2016-02-01

    In this review, we discuss the observations that, following chronic high-fat diet (HFD) exposure, male mice have higher levels of saturated fatty acids (FAs) and total sphingolipids, whereas lower amounts of polyunsaturated FAs in the central nervous system (CNS) than females. Furthermore, males, when compared with female mice, have higher levels of inflammatory markers in the hypothalamus following exposure to HFD. The increase in markers of inflammation in male mice is possibly due to the reductions in proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) and estrogen receptor alpha (ERα), which is not recapitulated in female mice. Consistently, hypothalamic inflammation is induced both in male and female ERα total-body knockout mice when exposed to a HFD, thus confirming the key role of ERα in the regulation of HFD-induced hypothalamic inflammation. Finally, the HFD-induced depletion of hypothalamic ERα is associated with dysregulation in metabolic homeostasis, as evidenced by reductions in glucose tolerance and decrements in myocardial function. PMID:26073655

  20. Hypolipidemic effect of pantothenic acid derivatives in mice with hypothalamic obesity induced by aurothioglucose.

    PubMed

    Naruta, E; Buko, V

    2001-10-01

    The hypolipidemic effects of pantothenic acid derivatives (phosphopantothenate, panthenol and pantethine) were studied in mice with hypothalamic obesity. Hypothalamic obesity in mice was induced by single injection of aurothioglucose (300 mg/kg body wt, i.p.). All the tested substances were administered during the last 10 days before decapitation (i.m., of dosage equivalent to 150 mg/kg body wt of phosphopantothenate). The studied substances inhibited the weight gain of the animals with hypothalamic obesity over the last 10 days of the experiment. The treatment with aurothioglucose increased food intake and mean body weight, blood glucose level; insulin, serum total cholesterol, triglyceride, the sum of LDL + VLDL and LDL-cholesterol concentration; triglyceride and cholesterol fractions in the liver; triglyceride and FFA content as well as lipoprotein lipase activity in adipose tissue of experimental mice. The administration of the assay compounds lowered food intake and mean body weight, insulin and glucose levels and decreased the content of triglycerides, total cholesterol and cholesterol esters in serum and adipose tissue as well as raised the activity of lipoprotein lipase in adipose tissue and serum lipolytic activity in obese mice. Among the compounds studied the reverse effect of panthenol was especially pronounced. The mechanism of hypolipidemic effects of pantothenic acid derivatives can be related to the reduced resistance to insulin and activation of lipolysis in serum and adipose tissue. PMID:11817109

  1. Successful resection of Hypothalamic Hamartoma with intractable gelastic seizures--by transcallosal subchoroidal approach.

    PubMed

    Bunyaratavej, Krishnapundha; Locharernkul, Chaichon; Tepmongkol, Supatporn; Lerdlum, Sukalaya; Shuangshoti, Shanop; Khaoroptham, Surachai

    2006-08-01

    A 19-year old female with intractable gelastic seizures was found to have 0.7 x 1.8 x 1.8 cm elliptical mass on the floor of the third ventricle. The signal intensity on the Magnetic Resonance Imaging (MRI) was consistent with the Hypothalamic Hamartoma (HH). Ictal EEG demonstrated rhythmic 7 Hz waves over Fp2, F4, and C4 with spreading to the right temporal region and then bilaterally. Ictal Single Photon Emission Computerized Tomography (SPECT) showed hyperperfusion at hypothalamic and medial frontopolar regions. The patient underwent surgical resection using Trans Callosal Subchoroidal Approach (TCSA) to the third ventricle. Pathological finding confirmed the diagnosis of hypothalamic hamartoma. Following the operation, she has been seizure free up to 12 months. Thereafter, provoked seizures seldom occurred and there has been improvement in her memory, emotional control and independence. This appears to be the first report of this surgical approach for HH, which is less likely to disturb memory function compared to previously described interfoniceal approach. PMID:17048440

  2. Effect of chronic d-fenfluramine administration on rat hypothalamic serotonin levels and release

    NASA Technical Reports Server (NTRS)

    Schaechter, Judith D.; Wurtman, Richard J.

    1988-01-01

    D-fenfluramine, an anorectic agent in rats and man, was administered daily at doses 1.25, 2.5, 5, or 10 mg/kg/day for 10 days, and sacrificed 6 days later. Hypothalamic serotonin (5-HT) levels were unchanged in rats receiving 1.25-5 mg/kg/day of d-fenfluramine but reduced by 22 percent (p less than 0.01) at the highest drug dose (10 mg/kg/day); hypothalamic 5-hydroxyindole acetic acid (5-HIAA) levels were reduced by 15 percent (p less than 0.05) or 28 percent (p less than 0.01) in rats receiving 5 or 10 mg/kg/day of the drug, respectively. Hypothalamic slices prepared from rats which were previously treated with any of the drug doses spontaneously released endogenous 5-HT at rates that did not differ from those of vehicle-treated rats. 5-HT released with electrical field-stimulation was unaffected by prior d-fenfluramine treatment at doses of 1.25-5 mg/kg/day, and was reduced by 20 percent (p less than 0.05) from slices prepared from rats which received 10 mg/kg/day. 5-HIAA efflux was also attenuated by the highest drug dose. These data indicate that chronic administration to rats of customary anorectic doses of d-fenfluramine (i.e. 0.06-1.25 mg/kg) fail to cause long-lasting reductions in brain 5-HT release.

  3. Algae Undaria pinnatifida Protects Hypothalamic Neurons against Endoplasmic Reticulum Stress through Akt/mTOR Signaling.

    PubMed

    Kim, Jongwan; Moon, Il Soo; Goo, Tae-Won; Moon, Seong-Su; Seo, Minchul

    2015-01-01

    Increased endoplasmic reticulum (ER) stress is known to be one of the causes of hypothalamic neuronal damage, as well as a cause of metabolic disorders such as obesity and diabetes. Recent evidence has suggested that Undaria pinnatifida (UP), an edible brown algae, has antioxidant activity. However, the neuroprotective effect of UP has yet to be examined. In this study, to investigate the neuroprotective effect of UP on ER stress-induced neuronal damage in mouse hypothalamic neurons, mice immortal hypothalamic neurons (GT1-7) were incubated with extract of UP. ER stress was induced by treating with tunicamycin. Tunicamycin induced apoptotic cell death was compared with the vehicle treatment through excessive ER stress. However UP protected GT1-7 cells from cell death, occurring after treatment with tunicamycin by reducing ER stress. Treatment with UP resulted in reduced increment of ATF6 and CHOP, and recovered the decrease of phosphorylation of Akt/mTOR by tunicamycin and the increment of autophagy. These results show that UP protects GT1-7 cells from ER stress induced cell death through the Akt/mTOR pathway. The current study suggests that UP may have a beneficial effect on cerebral neuronal degeneration in metabolic diseases with elevated ER stress. PMID:26610463

  4. Differential effects of leucine on translation initiation factor activation and protein synthesis in skeletal muscle, renal and adipose tissues of neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In adult rats, protein synthesis in skeletal muscle and adipose tissue increases in response to pharmacological doses of leucine (Leu) administered orally. In neonatal pigs, a physiological increase in plasma leucine stimulates protein synthesis in skeletal muscle without increasing hepatic protein...

  5. Leucine supplementation of a low-protein meal increases skeletal muscle and visceral tissue protein synthesis in neonatal pigs by stimulating mTOR-dependent translation initiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protein synthesis and eukaryotic initiation factor (eIF) activation are increased in skeletal muscle of neonatal pigs parenterally infused with amino acids. Leucine appears to be the most effective single amino acid to trigger these effects. To examine the response to enteral leucine supplementation...

  6. Chronic leucine supplementation of a low protein diet increases protein synthesis in skeletal muscle and visceral tissues of neonatal pigs through mTOR signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leucine acutely stimulates protein synthesis by activating the mammalian target of rapamycin (mTOR) signaling pathway. We hypothesized that leucine supplementation of a low protein diet will enhance protein synthesis and mTOR signaling in the neonate for prolonged periods. Fasted 5-d-old pigs (n=6–8...

  7. LEUCINE-NITROGEN METABOLISM IN THE BRAIN OF CONSCIOUS RATS: ITS ROLE AS A NITROGEN CARRIER IN GLUTAMATE SYNTHESIS IN GLIAL AND NEURONAL METABOLIC COMPARTMENTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The source of nitrogen (N) for the de novo synthesis of brain glutamate, glutamine, and gamma-aminobutyrate (GABA)remains controversial. Because leucine is readily transported into the brain and the brain contains high activities of branched-chain aminotransferase, we hypothesized that leucine is th...

  8. Amino acid availability and age affect the leucine stimulation of protein synthesis and eIF4F formation in muscle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have previously shown that a physiological increase in plasma leucine for 60 and 120 min increases translation initiation factor activation in muscle of neonatal pigs. Although muscle protein synthesis is increased by leucine at 60 min, it is not maintained at 120 min, perhaps because of the decr...

  9. Characterization of epiphycan, a small proteoglycan with a leucine-rich repeat core protein.

    PubMed

    Johnson, H J; Rosenberg, L; Choi, H U; Garza, S; Höök, M; Neame, P J

    1997-07-25

    The epiphysis of developing bones is a cartilaginous structure that is eventually replaced by bone during skeletal maturation. We have separated a dermatan sulfate proteoglycan, epiphycan, from decorin and biglycan by using dissociative extraction of bovine fetal epiphyseal cartilage, followed by sequential ion-exchange, gel permeation, hydrophobic, and Zn2+ chelate chromatographic steps. Epiphycan is a member of the small leucine-rich proteoglycan family, contains seven leucine-rich repeats (LRRs), is related to osteoglycin (osteoinductive factor) (Bentz, H., Nathan, R. M., Rosen, D. M., Armstrong, R. M., Thompson, A. Y., Segarini, P. R., Mathews, M. C., Dasch, J., Piez, K. A., and Seyedin, S. M. (1989) J. Biol. Chem. 264, 20805-20810), and appears to be the bovine equivalent of the chick proteoglycan PG-Lb (Shinomura, T., and Kimata, K. (1992) J. Biol. Chem. 267, 1265-1270). The intact proteoglycan had a median size of approximately 133 kDa. The core protein was 46 kDa by electrophoretic analysis, had a calculated size of 34,271 Da, and had two approximately equimolar N termini (APTLES ... and ETYDAT ... ) separated by 11 amino acids. There were at least three O-linked oligosaccharides in the N-terminal region of the protein, based on blank cycles in Edman degradation and corresponding serine or threonine residues in the translated cDNA sequence. The glycosaminoglycans ranged in size from 23 to 34 kDa were more heterogeneous than those in other dermatan sulfate small leucine-rich proteoglycans and were found in the acidic N-terminal region of the protein core, N-terminal to the LRRs. A four-cysteine cluster was present at the N terminus of the LRRs, and a disulfide-bonded cysteine pair was present at the C terminus of the protein core. The seventh LRR and an N-linked oligosaccharide were between the two C-terminal cysteines. An additional potential N-glycosylation site near the C terminus did not appear to be substituted at a significant level. PMID:9228042

  10. A Hamiltonian replica exchange method for building protein-protein interfaces applied to a leucine zipper

    NASA Astrophysics Data System (ADS)

    Cukier, Robert I.

    2011-01-01

    Leucine zippers consist of alpha helical monomers dimerized (or oligomerized) into alpha superhelical structures known as coiled coils. Forming the correct interface of a dimer from its monomers requires an exploration of configuration space focused on the side chains of one monomer that must interdigitate with sites on the other monomer. The aim of this work is to generate good interfaces in short simulations starting from separated monomers. Methods are developed to accomplish this goal based on an extension of a previously introduced [Su and Cukier, J. Phys. Chem. B 113, 9595, (2009)] Hamiltonian temperature replica exchange method (HTREM), which scales the Hamiltonian in both potential and kinetic energies that was used for the simulation of dimer melting curves. The new method, HTREM_MS (MS designates mean square), focused on interface formation, adds restraints to the Hamiltonians for all but the physical system, which is characterized by the normal molecular dynamics force field at the desired temperature. The restraints in the nonphysical systems serve to prevent the monomers from separating too far, and have the dual aims of enhancing the sampling of close in configurations and breaking unwanted correlations in the restrained systems. The method is applied to a 31-residue truncation of the 33-residue leucine zipper (GCN4-p1) of the yeast transcriptional activator GCN4. The monomers are initially separated by a distance that is beyond their capture length. HTREM simulations show that the monomers oscillate between dimerlike and monomerlike configurations, but do not form a stable interface. HTREM_MS simulations result in the dimer interface being faithfully reconstructed on a 2 ns time scale. A small number of systems (one physical and two restrained with modified potentials and higher effective temperatures) are sufficient. An in silico mutant that should not dimerize because it lacks charged residues that provide electrostatic stabilization of the dimer

  11. L-leucine transport in human breast cancer cells (MCF-7 and MDA-MB-231): kinetics, regulation by estrogen and molecular identity of the transporter.

    PubMed

    Shennan, D B; Thomson, J; Gow, I F; Travers, M T; Barber, M C

    2004-08-30

    The transport of L-leucine by two human breast cancer cell lines has been examined. L-leucine uptake by MDA-MB-231 and MCF-7 cells was via a BCH-sensitive, Na+ -independent pathway. L-leucine uptake by both cell lines was inhibited by L-alanine, D-leucine and to a lesser extent by L-lysine but not by L-proline. Estrogen (17beta-estradiol) stimulated L-leucine uptake by MCF-7 but not by MDA-MB-231 cells. L-leucine efflux from MDA-MB-231 and MCF-7 cells was trans-stimulated by BCH in a dose-dependent fashion. The effect of external BCH on L-leucine efflux from both cell types was almost abolished by reducing the temperature from 37 to 4 degrees C. There was, however, a significant efflux of L-leucine under zero-trans conditions which was also temperature-sensitive. L-glutamine, L-leucine, D-leucine, L-alanine, AIB and L-lysine all trans-stimulated L-leucine release from MDA-MB-231 and MCF-7 cells. In contrast, D-alanine and L-proline had little or no effect. The anti-cancer agent melphalan inhibited L-leucine uptake by MDA-MB-231 cells but had no effect on L-leucine efflux. Quantitative real-time PCR revealed that LAT1 mRNA was approximately 200 times more abundant than LAT2 mRNA in MCF-7 cells and confirmed that MDA-MB-231 cells express LAT1 but not LAT2 mRNA. LAT1 mRNA levels were higher in MCF-7 cells than in MDA-MB-231 cells. Furthermore, LAT1 mRNA was more abundant than CD98hc mRNA in both MDA-MB-231 and MCF-7 cells. The results suggest that system L is the major transporter for L-leucine in both MDA-MB-231 and MCF-7 cells. It is possible that LAT1 may be the major molecular correlate of system L in both cell types. However, not all of the properties of system L reflected those of LAT1/LAT2/CD98hc. PMID:15328053

  12. HORIZON SENSING

    SciTech Connect

    Larry G. Stolarczyk

    2003-03-18

    With the aid of a DOE grant (No. DE-FC26-01NT41050), Stolar Research Corporation (Stolar) developed the Horizon Sensor (HS) to distinguish between the different layers of a coal seam. Mounted on mining machine cutter drums, HS units can detect or sense the horizon between the coal seam and the roof and floor rock, providing the opportunity to accurately mine the section of the seam most desired. HS also enables accurate cutting of minimum height if that is the operator's objective. Often when cutting is done out-of-seam, the head-positioning function facilitates a fixed mining height to minimize dilution. With this technology, miners can still be at a remote location, yet cut only the clean coal, resulting in a much more efficient overall process. The objectives of this project were to demonstrate the feasibility of horizon sensing on mining machines and demonstrate that Horizon Sensing can allow coal to be cut cleaner and more efficiently. Stolar's primary goal was to develop the Horizon Sensor (HS) into an enabling technology for full or partial automation or ''agile mining''. This technical innovation (R&D 100 Award Winner) is quickly demonstrating improvements in productivity and miner safety at several prominent coal mines in the United States. In addition, the HS system can enable the cutting of cleaner coal. Stolar has driven the HS program on the philosophy that cutting cleaner coal means burning cleaner coal. The sensor, located inches from the cutting bits, is based upon the physics principles of a Resonant Microstrip Patch Antenna (RMPA). When it is in proximity of the rock-coal interface, the RMPA impedance varies depending on the thickness of uncut coal. The impedance is measured by the computer-controlled electronics and then sent by radio waves to the mining machine. The worker at the machine can read the data via a Graphical User Interface, displaying a color-coded image of the coal being cut, and direct the machine appropriately. The Horizon Sensor

  13. Ten Years and Counting: Moving Leucine-Rich Repeat Kinase 2 Inhibitors to the Clinic

    PubMed Central

    West, Andrew B

    2015-01-01

    The burden that Parkinson's disease (PD) exacts on the population continues to increase year after year. Though refinement of symptomatic treatments continues at a reasonable pace, no accepted therapies are available to slow or prevent disease progression. The leucine-rich repeat kinase 2 (LRRK2) gene was identified in PD genetic studies and offers new hope for novel therapeutic approaches. The evidence linking LRRK2 kinase activity to PD susceptibility is presented, as well as seminal discoveries relevant to the prosecution of LRRK2 kinase inhibition. Finally, suggestions are made for predictive preclinical modeling and successful first-in-human trials. © 2014 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society. PMID:25448543

  14. LEUCINE-RICH AMELOGENIN PEPTIDE INDUCES OSTEOGENESIS IN MOUSE EMBRYONIC STEM CELLS

    PubMed Central

    Warotayanont, Rungnapa; Zhu, Danhong; Snead, Malcolm L.; Zhou, Yan

    2008-01-01

    Leucine-rich amelogenin peptide (LRAP), an alternatively spliced amelogenin protein, possesses a signaling property shown to induce osteogenic differentiation. In the current study, we detected LRAP expression during osteogenesis of wild-type (WT) embryonic stem (ES) cells and observed the absence of LRAP expression in amelogenin-null (KO) ES cells. We explored the signaling effect of LRAP on wild-type ES cells, and the ability of LRAP to rescue the impaired osteogenesis phenotype observed in KO ES cells. Our data indicate that LRAP treatment of WT and KO ES cells induces a significant increase in mineral matrix formation, and significant increases in bone sialoprotein and osterix gene expression. In addition, the amelogenin KO phenotype is partially rescued by the addition of exogenous LRAP. These data suggest a unique function of LRAP during ES cell differentiation along osteogenic lineage. PMID:18086559

  15. Studies on an L-leucine hydriodide semiorganic crystal for frequency conversion applications

    NASA Astrophysics Data System (ADS)

    Baskaran, P.; Vimalan, M.; Anandan, P.; Bakiyaraj, G.; Kirubavathi, K.; Praveen, S. G.; Selvaraju, K.

    2016-03-01

    An L-leucine hydriodide semiorganic crystal has been synthesized and grown by a slow evaporation technique. The lattice parameters of the grown crystal have been confirmed using single-crystal x-ray diffractometry. Various functional groups present in the crystal were identified by Fourier transform infrared (FTIR spectral) assessment. The optical transmission percentage of the crystal was ascertained by UV-vis-near-infrared (NIR) studies. The thermal stability of the crystal was determined by thermogravimetric and differential thermal analysis curves. The mechanical behavior of the crystal was studied using the Vicker’s microhardness analysis. The dielectric properties of the crystal have been investigated for varying temperatures. The second-harmonic generation efficiency was measured by the Kurtz and Perry powder technique and the efficiency is comparable to that of potassium dihydrogen orthophosphate.

  16. Regulation of Beta-Cell Function and Mass by the Dual Leucine Zipper Kinase.

    PubMed

    Oetjen, Elke

    2016-06-01

    Diabetes mellitus is one of the most rapidly increasing diseases worldwide, whereby approximately 90-95% of patients suffer from type 2 diabetes. Considering its micro- and macrovascular complications like blindness and myocardial infarction, a reliable anti-diabetic treatment is needed. Maintaining the function and the mass of the insulin producing beta-cells despite elevated levels of beta-cell-toxic prediabetic signals represents a desirable mechanism of action of anti-diabetic drugs. The dual leucine zipper kinase (DLK) inhibits the action of two transcription factors within the beta-cell, thereby interfering with insulin secretion and production and the conservation of beta-cell mass. Furthermore, DLK action is regulated by prediabetic signals. Hence, the inhibition of this kinase might protect beta-cells against beta-cell-toxic prediabetic signals and prevent the development of diabetes. DLK might thus present a novel drug target for the treatment of diabetes mellitus type 2. PMID:27100796

  17. Assembly of Neuronal Connectivity by Neurotrophic Factors and Leucine-Rich Repeat Proteins.

    PubMed

    Ledda, Fernanda; Paratcha, Gustavo

    2016-01-01

    Proper function of the nervous system critically relies on sophisticated neuronal networks interconnected in a highly specific pattern. The architecture of these connections arises from sequential developmental steps such as axonal growth and guidance, dendrite development, target determination, synapse formation and plasticity. Leucine-rich repeat (LRR) transmembrane proteins have been involved in cell-type specific signaling pathways that underlie these developmental processes. The members of this superfamily of proteins execute their functions acting as trans-synaptic cell adhesion molecules involved in target specificity and synapse formation or working in cis as cell-intrinsic modulators of neurotrophic factor receptor trafficking and signaling. In this review, we will focus on novel physiological mechanisms through which LRR proteins regulate neurotrophic factor receptor signaling, highlighting the importance of these modulatory events for proper axonal extension and guidance, tissue innervation and dendrite morphogenesis. Additionally, we discuss few examples linking this set of LRR proteins to neurodevelopmental and psychiatric disorders. PMID:27555809

  18. Assembly of Neuronal Connectivity by Neurotrophic Factors and Leucine-Rich Repeat Proteins

    PubMed Central

    Ledda, Fernanda; Paratcha, Gustavo

    2016-01-01

    Proper function of the nervous system critically relies on sophisticated neuronal networks interconnected in a highly specific pattern. The architecture of these connections arises from sequential developmental steps such as axonal growth and guidance, dendrite development, target determination, synapse formation and plasticity. Leucine-rich repeat (LRR) transmembrane proteins have been involved in cell-type specific signaling pathways that underlie these developmental processes. The members of this superfamily of proteins execute their functions acting as trans-synaptic cell adhesion molecules involved in target specificity and synapse formation or working in cis as cell-intrinsic modulators of neurotrophic factor receptor trafficking and signaling. In this review, we will focus on novel physiological mechanisms through which LRR proteins regulate neurotrophic factor receptor signaling, highlighting the importance of these modulatory events for proper axonal extension and guidance, tissue innervation and dendrite morphogenesis. Additionally, we discuss few examples linking this set of LRR proteins to neurodevelopmental and psychiatric disorders. PMID:27555809

  19. Characterization of the conglomerate form of acetyl-DL-leucine by thermal analysis and solubility measurements

    NASA Astrophysics Data System (ADS)

    Estime, N.; Pena, R.; Teychené, S.; Autret, J. M.; Biscans, B.

    2012-03-01

    Starting from a mixture of enantiomers in solution, crystallization can generate different types of crystals. In order to determine which type of crystal is obtained in the case of acetyl leucine, an active pharmaceutical ingredient (API), analytical methods have been used to partially elucidate the binary and ternary phase diagrams of the system composed of the two enantiomers and water. The melting temperature phase diagram of this compound has been obtained by using differential scanning calorimetry (DSC) analyzes. The results show that it is characteristic of a conglomerate. This mode of crystallization has also been confirmed by X-ray powder diffraction analysis. Solubility measurements of enantiomerical mixtures in water enabled the determination of the ternary diagram of solubility. The empiric Meyerhoffer double solubility rule has been modified, due to the characterization of interactions between enantiomers.

  20. Structural basis for the regulation of maternal embryonic leucine zipper kinase.

    PubMed

    Cao, Lu-Sha; Wang, Jue; Chen, Yuling; Deng, Haiteng; Wang, Zhi-Xin; Wu, Jia-Wei

    2013-01-01

    MELK (maternal embryonic leucine zipper kinase), which is a member of the AMPK (AMP-activated protein kinase)-related kinase family, plays important roles in diverse cellular processes and has become a promising drug target for certain cancers. However, the regulatory mechanism of MELK remains elusive. Here, we report the crystal structure of a fragment of human MELK that contains the kinase domain and ubiquitin-associated (UBA) domain. The UBA domain tightly binds to the back of the kinase domain, which may contribute to the proper conformation and activity of the kinase domain. Interestingly, the activation segment in the kinase domain displays a unique conformation that contains an intramolecular disulfide bond. The structural and biochemical analyses unravel the molecular mechanisms for the autophosphorylation/activation of MELK and the dependence of its catalytic activity on reducing agents. Thus, our results may provide the basis for designing specific MELK inhibitors for cancer treatment. PMID:23922895

  1. Glucocorticoid-induced leucine zipper (GILZ) in immuno suppression: master regulator or bystander?

    PubMed Central

    Hoppstädter, Jessica; Kiemer, Alexandra K.

    2015-01-01

    Induction of glucocorticoid-induced leucine zipper (GILZ) by glucocorticoids has been reported to be essential for their anti-inflammatory actions. At the same time, GILZ is actively downregulated under inflammatory conditions, resulting in an enhanced pro-inflammatory response. Two papers published in the recent past showed elevated GILZ expression in the late stage of an inflammation. Still, the manuscripts suggest seemingly contradictory roles of endogenous GILZ: one of them suggested compensatory actions by elevated corticosterone levels in GILZ knockout mice, while our own manuscript showed a distinct phenotype upon GILZ knockout in vivo. Herein, we discuss the role of GILZ in inflammation with a special focus on the influence of endogenous GILZ on macrophage responses and suggest a cell-type specific action of GILZ as an explanation for the conflicting results as presented in recent reports. PMID:26498359

  2. Acute effects of enteral leucine supplementation of a low protein diet on muscle protein synthesis in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protein synthesis and eukaryotic initiation factor (eIF) activation are increased in skeletal muscle of neonatal pigs parenterally infused with insulin and amino acids (AA), particularly leucine. We hypothesized that enteral Leu supplementation of a low protein diets in neonatal pigs will acutely in...

  3. Rapamycin blocks leucine-induced protein synthesis by suppressing mTORC1 activation in skeletal muscle of neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Skeletal muscle in the neonate grows at a rapid rate due in part to an enhanced sensitivity to the postprandial rise in amino acids, particularly leucine (Leu). To elucidate the molecular mechanism by which Leu stimulates protein synthesis in neonatal muscle, overnight fasted 7-day-old piglets were...

  4. An alternative domain containing a leucine-rich sequence regulates nuclear cytoplasmic localization of protein 4.1R.

    PubMed

    Luque, Carlos M; Pérez-Ferreiro, Carmen M; Pérez-Gonzalez, Alicia; Englmeier, Ludwig; Koffa, Maria D; Correas, Isabel

    2003-01-24

    In red blood cells, protein 4.1 (4.1R) is an 80-kDa protein that stabilizes the spectrin-actin network and anchors it to the plasma membrane. The picture is more complex in nucleated cells, in which many 4.1R isoforms, varying in size and intracellular location, have been identified. To contribute to the characterization of signals involved in differential intracellular localization of 4.1R, we have analyzed the role the exon 5-encoded sequence plays in 4.1R distribution. We show that exon 5 encodes a leucine-rich sequence that shares key features with nuclear export signals (NESs). This sequence adopts the topology employed for NESs of other proteins and conserves two hydrophobic residues that are shown to be critical for NES function. A 4.1R isoform expressing the leucine-rich sequence binds to the export receptor CRM1 in a RanGTP-dependent fashion, whereas this does not occur in a mutant whose two conserved hydrophobic residues are substituted. These two residues are also essential for 4.1R intracellular distribution, because the 4.1R protein containing the leucine-rich sequence localizes in the cytoplasm, whereas the mutant protein predominantly accumulates in the nucleus. We hypothesize that the leucine-rich sequence in 4.1R controls distribution and concomitantly function of a specific set of 4.1R isoforms. PMID:12427749

  5. Introduction of a leucine half-zipper engenders multiple high-quality crystals of a recalcitrant tRNA synthetase

    SciTech Connect

    Guo, Min; Shapiro, Ryan; Schimmel, Paul; Yang, Xiang-Lei

    2010-03-01

    E. coli alanyl-tRNA synthetase is recalcitrant to crystallization. A group of leucine substitutions has transformed the protein. Although Escherichia coli alanyl-tRNA synthetase was among the first tRNA synthetases to be sequenced and extensively studied by functional analysis, it has proved to be recalcitrant to crystallization. This challenge remained even for crystallization of the catalytic fragment. By mutationally introducing three stacked leucines onto the solvent-exposed side of an α-helix, an engineered catalytic fragment of the synthetase was obtained that yielded multiple high-quality crystals and cocrystals with different ligands. The engineered α-helix did not form a leucine zipper that interlocked with the same α-helix from another molecule. Instead, using the created hydrophobic spine, it interacted with other surfaces of the protein as a leucine half-zipper (LHZ) to enhance the crystal lattice interactions. The LHZ made crystal lattice contacts in all crystals of different space groups. These results illustrate the power of introducing an LHZ into helices to facilitate crystallization. The authors propose that the method can be unified with surface-entropy reduction and can be broadly used for protein-surface optimization in crystallization.

  6. L-leucine transport systems in Saccharomyces cerevisiae participation of GAP1, S1 and S2 transport systems.

    PubMed

    Kotliar, N; Stella, C A; Ramos, E H; Mattoon, J R

    1994-09-01

    L-leucine uptake in Saccharomyces cerevisiae is mediated by three different transport systems, S1, S2 and GAP1. Their activities are dependent on the nitrogen source of the culture media. Wild type cells grown in L-proline exhibit a single transport system with high affinity and high Vmax that is partially inhibited by L-citrulline. A gap1 mutant shows two transport systems with Km and Vmax values similar to those previously described as S1 and S2, this transport activity is not inhibited by D-leucine, D-isoleucine or D-valine. Two systems can be also determined in wild type cells grown in rich medium containing a mixed nitrogen source where decreased GAP1 function is observed. In either wild type or gap1 cells grown in medium containing ammonium ions as sole nitrogen source, L-leucine uptake kinetics shows two systems with lower Vmax and similar Km values to those of the S1 and S2 systems. These results show that in S. cerevisiae GAP1, S1 and S2 participate in L-leucine entrance in cells grown in a poor nitrogen source, and that S1 and S2 are two ammonia-sensitive permeases that mediate the uptake in cells grown in a rich nitrogen source. PMID:7812191

  7. Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BACKGROUND: The effects of essential amino acid (EAA) supplementation during moderate steady state (ie, endurance) exercise on postexercise skeletal muscle metabolism are not well described, and the potential role of supplemental leucine on muscle protein synthesis (MPS) and associated molecular re...

  8. Modeling leucine's metabolic pathway and knockout prediction improving the production of surfactin, a biosurfactant from Bacillus subtilis.

    PubMed

    Coutte, François; Niehren, Joachim; Dhali, Debarun; John, Mathias; Versari, Cristian; Jacques, Philippe

    2015-08-01

    A Bacillus subtilis mutant strain overexpressing surfactin biosynthetic genes was previously constructed. In order to further increase the production of this biosurfactant, our hypothesis is that the surfactin precursors, especially leucine, must be overproduced. We present a three step approach for leucine overproduction directed by methods from computational biology. Firstly, we develop a new algorithm for gene knockout prediction based on abstract interpretation, which applies to a recent modeling language for reaction networks with partial kinetic information. Secondly, we model the leucine metabolic pathway as a reaction network in this language, and apply the knockout prediction algorithm with the target of leucine overproduction. Out of the 21 reactions corresponding to potential gene knockouts, the prediction algorithm selects 12 reactions. Six knockouts were introduced in B. subtilis 168 derivatives strains to verify their effects on surfactin production. For all generated mutants, the specific surfactin production is increased from 1.6- to 20.9-fold during the exponential growth phase, depending on the medium composition. These results show the effectiveness of the knockout prediction approach based on formal models for metabolic reaction networks with partial kinetic information, and confirms our hypothesis that precursors supply is one of the main parameters to optimize surfactin overproduction. PMID:26220295

  9. Distinct Plasma Profile of Polar Neutral Amino Acids, Leucine, and Glutamate in Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Tirouvanziam, Rabindra; Obukhanych, Tetyana V.; Laval, Julie; Aronov, Pavel A.; Libove, Robin; Banerjee, Arpita Goswami; Parker, Karen J.; O'Hara, Ruth; Herzenberg, Leonard A.; Herzenberg, Leonore A.; Hardan, Antonio Y.

    2012-01-01

    The goal of this investigation was to examine plasma amino acid (AA) levels in children with Autism Spectrum Disorders (ASD, N = 27) and neuro-typically developing controls (N = 20). We observed reduced plasma levels of most polar neutral AA and leucine in children with ASD. This AA profile conferred significant post hoc power for discriminating…

  10. Pulsatile delivery of a leucine supplement during long-term continuous enteral feeding enhances lean growth in term neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Neonatal pigs are used as a model to study and optimize the clinical treatment of infants who are unable to maintain oral feeding. Using this model, we have previously shown that pulsatile administration of leucine during continuous feeding over 24 h via orogastric tube enhanced protein synthesis in...

  11. Mitochondrial and sarcoplasmic proteins, but not myosin heavy chain, are sensitive to leucine supplementation in old rat skeletal muscle.

    PubMed

    Guillet, Christelle; Zangarelli, Aude; Mishellany, Anne; Rousset, Paulette; Sornet, Claire; Dardevet, Dominique; Boirie, Yves

    2004-05-01

    Leucine has a major anabolic impact on muscle protein synthesis in young as in old animals. However, myosin heavy chain (MHC), sarcoplasmic and mitochondrial proteins may differently respond to anabolic factors, especially during aging. To test this hypothesis, fractional synthesis rates (FSR) of the three muscle protein fractions were measured using a flooding dose of [1-(13)C] phenylalanine, in gastrocnemius muscle of adult (8 months) and old (22 months) rats, either in postabsorptive state (PA), or 90-120 min after ingestion of a alanine-supplemented meal (PP+A) or a leucine-supplemented meal (PP+L). In adult and old rats, in comparison with PA, leucine stimulated mitochondrial (adult: 0.260+/-0.011 vs 0.238+/-0.012%h(-1); old: 0.289+/-0.010 vs 0.250+/-0.010%h(-1); PP+L vs PA, P<0.05) and sarcoplasmic (adult: 0.182+/-0.011 vs 0.143+/-0.006%h(-1); old: 0.195+/-0.010 vs 0.149+/-0.008%h(-1); PP+L vs PA, P<0.05) protein FSR, but not MHC synthesis in old rats (0.101+/-0.009 vs 0.137+/-0.018%h(-1); PP+L vs PA, P=NS). In conclusion, synthesis of specific muscle protein is activated by leucine supplementation, but MHC may be less sensitive to anabolic factors with aging. PMID:15130669

  12. Leucine and alpha-Ketoisocaproic acid, but not norleucine, stimulate skeletal muscle protein synthesis in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The branched-chain amino acid, leucine, acts as a nutrient signal to stimulate protein synthesis in skeletal muscle of young pigs. However, the chemical structure responsible for this effect has not been identified. We have shown that the other branched-chain amino acids, isoleucine and valine, are ...

  13. CORRELATION BETWEEN CYTOPLASMIC DOMAIN SEQUENCE AND AUTOPHOSPHORYLATION AMONG ARABIDOPSIS LEUCINE-RICH REPEAT RECEPTOR-LIKE KINASES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The leucine-rich repeat receptor-like kinases (LRR-RLKs) are implicated in signaling roles during plant growth, development and defense. A paradigm for receptor kinase activation involves dimerization and auto- or trans-phosphorylation within the cytoplasmic domain. Our goals are to identify intrace...

  14. RNA interference targeting leucine aminopeptidase blocks hatching of Schistosoma mansoni eggs

    PubMed Central

    Rinaldi, Gabriel; Morales, Maria E.; Alrefaei, Yousef N.; Cancela, Martín; Castillo, Estela; Dalton, John P.; Tort, José F.; Brindley, Paul J.

    2009-01-01

    Schistosoma mansoni leucine aminopeptidase (LAP) is thought to play a central role in hatching of the miracidium from the schistosome egg. We identified two discrete LAPs genes in the Schistosoma mansoni genome, and their orthologs in S. japonicum. The similarities in sequence and exon/intron structure of the two genes, LAP1 and LAP2, suggest that they arose by gene duplication and that this occurred before separation of the mansoni and japonicum lineages. The SmLAP 1 and 2 genes have different expression patterns in diverse stages of the cycle; whereas both are equally expressed in the blood dwelling stages (schistosomules and adult), SmLAP 2 expression was higher in free living larval (miracidia) and in parasitic intra-snail (sporocysts) stages. We investigated the role of each enzyme in hatching of schistosome eggs and the early stages of schistosome development by RNA interference (RNAi). Using RNAi, we observed marked and specific reduction of mRNAs, along with a loss of exopeptidase activity in soluble parasite extracts against the diagnostic substrate L-leucine-7-amido-4-methylcoumarin hydroxide. Strikingly, knockdown of either SmLAP1 or SmLAP2, or both together, was accompanied by ≥ 80% inhibition of hatching of schistosome eggs showing that both enzymes are important to the escape of miracidia from the egg. The methods employed here refine the utility of RNAi for functional genomics studies in helminth parasites and confirm these can be used to identify potential drug targets, in this case schistosome aminopeptidases. PMID:19463860

  15. Characterization of an N-glycosylated Bacillus subtilis leucine aminopeptidase expressed in Pichia pastoris.

    PubMed

    Xi, Hongxing; Tian, Yaping; Zhou, Nandi; Zhou, Zhemin; Shen, Wei

    2015-02-01

    Aminopeptidase is an important flavorsome especially in protein hydrolysate debittering by removing hydrophobic amino acid residue at the N-terminal end. Besides, it is also applied to preparation of active peptides and analysis of protein sequence. In this study, leucine aminopeptidase from Bacillus subtilis was cloned and expressed in Pichia pastoris, a widely used heterologous protein expression host. Then it was purified and characterized. After methanol induction for 96 h, the aminopeptidase activity in culture supernatant reached 28.4 U ml(À1) , which was 7.1 times that of wild strain B. subtilis Zj016. The optimal temperature and pH of the purified recombinant enzyme were 60 °C and 8.5, respectively. The purified aminopeptidase was stable within 30-60 °C and pH 8.0-9.0. It was intensively inhibited by Ni(2β) , Ca(2β) , DL-dithiothreitol (DTT) and ethylene diamine tetraacetic acid (EDTA), but activated by Co(2β) . The Km toward leucine-p-nitroanilines (Leu-pNA) of the enzyme was 0.97 mM. The sequence analysis of aminopeptidase indicated three potential N-glycosylation sites and it was further verified via MALDI-TOF-MS analysis. Consequently, the N-glycosylated aminopeptidase exhibited higher thermostability and catalytic efficiency. The purified enzyme exhibited two bands through sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) while a single band can be identified when the enzyme was deglycosylated. Circular dichroism spectroscopy indicated that the secondary structure of recombinant aminopeptidase was similar to the wild-type. PMID:25389014

  16. Mutational Analysis of the Arabidopsis Nucleotide Binding Site–Leucine-Rich Repeat Resistance Gene RPS2

    PubMed Central

    Tao, Yi; Yuan, Fenghua; Leister, R. Todd; Ausubel, Frederick M.; Katagiri, Fumiaki

    2000-01-01

    Disease resistance proteins containing a nucleotide binding site (NBS) and a leucine-rich repeat (LRR) region compose the largest class of disease resistance proteins. These so-called NBS-LRR proteins confer resistance against a wide variety of phytopathogens. To help elucidate the mechanism by which NBS-LRR proteins recognize and transmit pathogen-derived signals, we analyzed mutant versions of the Arabidopsis NBS-LRR protein RPS2. The RPS2 gene confers resistance against Pseudomonas syringae strains carrying the avirulence gene avrRpt2. The activity of RPS2 derivatives in response to AvrRpt2 was measured by using a functional transient expression assay or by expressing the mutant proteins in transgenic plants. Directed mutagenesis revealed that the NBS and an N-terminal leucine zipper (LZ) motif were critical for RPS2 function. Mutations near the N terminus, including an LZ mutation, resulted in proteins that exhibited a dominant negative effect on wild-type RPS2. Scanning the RPS2 molecule with a small in-frame internal deletion demonstrated that RPS2 does not have a large dispensable region. Overexpression of RPS2 in the transient assay in the absence of avrRpt2 also led to an apparent resistant response, presumably a consequence of a low basal activity of RPS2. The NBS and LZ were essential for this overdose effect, whereas the entire LRR was dispensable. RPS2 interaction with a 75-kD protein (p75) required an N-terminal portion of RPS2 that is smaller than the region required for the overdose effect. These findings illuminate the pathogen recognition mechanisms common among NBS-LRR proteins. PMID:11148296

  17. Diurnal pattern of the interrelationships among leucine oxidation, urea production, and hydrolysis in humans.

    PubMed

    el-Khoury, A E; Ajami, A M; Fukagawa, N K; Chapman, T E; Young, V R

    1996-09-01

    We investigated in six healthy adult men, who received an adequate intake of protein (1 g.kg-1.day-1), the relationship among urea production, excretion, and hydrolysis. At the end of a 6-day diet-adjustment period, subjects were studied using a 24-h continuous intravenous [1-13C]leucine and [15N,15N]urea tracer protocol (A. E. El-Khoury, N. K. Fukagawa, M. Sánchez, R. H. Tsay, R. E. Gleason, T. E. Chapman, and V. R. Young. Am. J. Clin. Nutr. 59: 1000-1011, 1994) to determine rates of irreversible protein nitrogen loss and urea kinetics. By combining leucine and urea kinetic data, we found a significant degree of urea hydrolysis over the 24-h period but no evidence to support the thesis that there is a net retention or "salvage" of the urea nitrogen liberated. Our measurements revealed little or no urea hydrolysis during the fed 12-h period of the 24-h tracer protocol but substantial hydrolysis during the 12-h fasting phase. Furthermore, a mass balance model and calculations (APPENDIX) indicated that nitrogen salvage, if any, is quantitatively indistinguishable from insensible nitrogen losses and aggregate estimation errors, accounting for no more than 5% of the nitrogen intake. We conclude that urea hydrolysis, via the intestinal microflora, although representing a component of the overall cycles of nitrogen flow within the body, does not contribute via a net retention of amino nitrogen to the maintenance of body nitrogen homeostasis in healthy adults consuming an adequate diet. PMID:8843752

  18. Linkage Relationships of Genes Controlling Isoleucine, Valine, and Leucine Biosynthesis in Bacillus subtilis

    PubMed Central

    Barat, M.; Anagnostopoulos, C.; Schneider, A.-M.

    1965-01-01

    Barat, M. (Centre National de la Recherche Scientifique, Gif-sur-Yvette, Seine et Oise, France), C. Anagnostopoulos, and A.-M. Schneider. Linkage relationships of genes controlling isoleucine, valine, and leucine biosynthesis in Bacillus subtilis. J. Bacteriol.90:357–369. 1965.—In Bacillus subtilis, the genetic loci controlling isoleucine and valine biosynthesis are not all clustered. Some of them were located on two distinct transforming deoxyribonucleic acid “molecules.” One of these molecules (the “ileilva2–4-met segment”) carries the threonine deaminase and the dihydroxy acid dehydrase loci linked to methionine markers. The other (the “ilva1–3-leu segment”) bears the reductoisomerase locus and one or more loci involved in leucine synthesis. A phenylalanine marker was also shown to be weakly linked to this latter group. In transduction mediated by phage PBS-1, these groups are transferred jointly with other gene clusters. The phage appears to convey chromosome fragments considerably longer than the transforming “molecules.” The genetic maps of both the above segments were extended by transduction. Some groups previously studied by transformation can be placed in the following linear order: the ile-ilva2–4-met segment, the cluster of loci involved in aromatic amino acid synthesis (try segment), and a lysine locus. An arginine locus is cotransduced with the phe-ilva1–2-leu segment. Recombination frequencies between linked markers are much lower in transduction by this phage than in transformation. PMID:14329448

  19. Metabolic labeling of leucine rich repeat kinases 1 and 2 with radioactive phosphate.

    PubMed

    Taymans, Jean-Marc; Gao, Fangye; Baekelandt, Veerle

    2013-01-01

    Leucine rich repeat kinases 1 and 2 (LRRK1 and LRRK2) are paralogs which share a similar domain organization, including a serine-threonine kinase domain, a Ras of complex proteins domain (ROC), a C-terminal of ROC domain (COR), and leucine-rich and ankyrin-like repeats at the N-terminus. The precise cellular roles of LRRK1 and LRRK2 have yet to be elucidated, however LRRK1 has been implicated in tyrosine kinase receptor signaling, while LRRK2 is implicated in the pathogenesis of Parkinson's disease. In this report, we present a protocol to label the LRRK1 and LRRK2 proteins in cells with (32)P orthophosphate, thereby providing a means to measure the overall phosphorylation levels of these 2 proteins in cells. In brief, affinity tagged LRRK proteins are expressed in HEK293T cells which are exposed to medium containing (32)P-orthophosphate. The (32)P-orthophosphate is assimilated by the cells after only a few hours of incubation and all molecules in the cell containing phosphates are thereby radioactively labeled. Via the affinity tag (3xflag) the LRRK proteins are isolated from other cellular components by immunoprecipitation. Immunoprecipitates are then separated via SDS-PAGE, blotted to PVDF membranes and analysis of the incorporated phosphates is performed by autoradiography ((32)P signal) and western detection (protein signal) of the proteins on the blots. The protocol can readily be adapted to monitor phosphorylation of any other protein that can be expressed in cells and isolated by immunoprecipitation. PMID:24084685

  20. Hypothalamic Non-AgRP, Non-POMC GABAergic Neurons Are Required for Postweaning Feeding and NPY Hyperphagia

    PubMed Central

    Kim, Eun Ran; Wu, Zhaofei; Sun, Hao; Xu, Yuanzhong; Mangieri, Leandra R.; Xu, Yong

    2015-01-01

    The hypothalamus is critical for feeding and body weight regulation. Prevailing studies focus on hypothalamic neurons that are defined by selectively expressing transcription factors or neuropeptides including those expressing proopiomelanocortin (POMC) and agouti-related peptides (AgRP). The Cre expression driven by the pancreas-duodenum homeobox 1 promoter is abundant in several hypothalamic nuclei but not in AgRP or POMC neurons. Using this line, we generated mice with disruption of GABA release from a major subset of non-POMC, non-AgRP GABAergic neurons in the hypothalamus. These mice exhibited a reduction in postweaning feeding and growth, and disrupted hyperphagic responses to NPY. Disruption of GABA release severely diminished GABAergic input to the paraventricular hypothalamic nucleus (PVH). Furthermore, disruption of GABA-A receptor function in the PVH also reduced postweaning feeding and blunted NPY-induced hyperphagia. Given the limited knowledge on postweaning feeding, our results are significant in identifying GABA release from a major subset of less appreciated hypothalamic neurons as a key mediator for postweaning feeding and NPY hyperphagia, and the PVH as one major downstream site that contributes significantly to the GABA action. SIGNIFICANCE STATEMENT Prevalent studies on feeding in the hypothalamus focus on well characterized, selective groups neurons [e.g., proopiomelanocortin (POMC) and agouti-related peptide (AgRP) neurons], and as a result, the role of the majority of other hypothalamic neurons is largely neglected. Here, we demonstrated an important role for GABAergic projections from non-POMC non-AgRP neurons to the paraventricular hypothalamic nucleus in promoting postweaning (mainly nocturnal) feeding and mediating NPY-induced hyperphagia. Thus, these results signify an importance to study those yet to be defined hypothalamic neurons in the regulation of energy balance and reveal a neural basis for postweaning (nocturnal) feeding and NPY