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Vág J, Nagy TL, Mikecs B. Sex-related differences in endothelium-dependent vasodilation of human gingiva. BMC Oral Health 2022; 22:177. [PMID: 35562729 PMCID: PMC9107103 DOI: 10.1186/s12903-022-02186-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 04/14/2022] [Indexed: 11/10/2022] Open
Abstract
Background Sex hormones influence circulation, periodontitis, and wound healing. The aim of the study was to compare the endothelium-dependent and independent vasodilation in human gingiva in men and women. Methods Gingival blood flow was evaluated in twelve male and twelve female subjects with healthy gingiva and no systemic conditions after acetylcholine or nitric oxide donor (NitroPOHL). Agonists were administered into the gingival sulcus at the right secondary incisor (test site). Regional gingival blood flow (GBF) was imaged by Laser Speckle Contrast Imager from the marginal gingiva to the mucogingival junction in four consecutive regions (coronal, midway1, midway2 and apical). Blood flow was expressed in Laser Speckle Perfusion Unit (LSPU). The absolute maximal blood flow change (Dmax), the area under the blood flow curve (AUC), and the time to peak (TTP) were calculated.
Results Males had higher baseline GBF than females (257 ± 18.2 vs. 225 ± 18.8 LSPU, p < 0.001). Acetylcholine and NitroPOHL significantly increased the GBF in all test regions. The Dmax after the acetylcholine was reduced apically compared to the coronal (90 ± 13 LSPU vs. 117 ± 7 LSPU, p < 0.01), but it was similar after NitroPOHL (78 ± 9 LSPU vs. 86 ± 6 LSPU, p = 0.398) in both sexes. The Dmax and AUC were higher, and the TTP was smaller in men in most regions after acetylcholine but not after NitroPOHL. Conclusion In the human gingiva, the endothelium-independent vasodilation propagates without attenuation in the line of the vascular supply in both sexes. At the same time, the endothelium-dependent ascending vasodilation attenuates similarly in men and women. However, men had more pronounced endothelium-dependent vasodilation than women. Therefore, it might contribute to the increased severity of periodontal disease in men. Trial registration The study was registered with ClinicalTrials.gov on 09.06.2021 (NCT04918563).
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Affiliation(s)
- János Vág
- Department of Conservative Dentistry, Faculty of Dentistry, Semmelweis University, Szentkirályi utca 47, Budapest, 1088, Hungary.
| | - Tamás László Nagy
- Department of Conservative Dentistry, Faculty of Dentistry, Semmelweis University, Szentkirályi utca 47, Budapest, 1088, Hungary
| | - Barbara Mikecs
- Department of Conservative Dentistry, Faculty of Dentistry, Semmelweis University, Szentkirályi utca 47, Budapest, 1088, Hungary
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2
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Müller TD, Blüher M, Tschöp MH, DiMarchi RD. Anti-obesity drug discovery: advances and challenges. Nat Rev Drug Discov 2022; 21:201-223. [PMID: 34815532 PMCID: PMC8609996 DOI: 10.1038/s41573-021-00337-8] [Citation(s) in RCA: 357] [Impact Index Per Article: 178.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2021] [Indexed: 12/27/2022]
Abstract
Enormous progress has been made in the last half-century in the management of diseases closely integrated with excess body weight, such as hypertension, adult-onset diabetes and elevated cholesterol. However, the treatment of obesity itself has proven largely resistant to therapy, with anti-obesity medications (AOMs) often delivering insufficient efficacy and dubious safety. Here, we provide an overview of the history of AOM development, focusing on lessons learned and ongoing obstacles. Recent advances, including increased understanding of the molecular gut-brain communication, are inspiring the pursuit of next-generation AOMs that appear capable of safely achieving sizeable and sustained body weight loss.
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Affiliation(s)
- Timo D. Müller
- grid.4567.00000 0004 0483 2525Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, Neuherberg, Germany ,grid.452622.5German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Matthias Blüher
- grid.411339.d0000 0000 8517 9062Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München at the University of Leipzig and University Hospital Leipzig, Leipzig, Germany
| | - Matthias H. Tschöp
- grid.4567.00000 0004 0483 2525Helmholtz Zentrum München, Neuherberg, Germany ,grid.6936.a0000000123222966Division of Metabolic Diseases, Department of Medicine, Technische Universität München, München, Germany
| | - Richard D. DiMarchi
- grid.411377.70000 0001 0790 959XDepartment of Chemistry, Indiana University, Bloomington, IN USA
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3
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Ano Y, Ohya R, Yamazaki T, Takahashi C, Taniguchi Y, Kondo K, Takashima A, Uchida K, Nakayama H. Hop bitter acids containing a β-carbonyl moiety prevent inflammation-induced cognitive decline via the vagus nerve and noradrenergic system. Sci Rep 2020; 10:20028. [PMID: 33208787 PMCID: PMC7674441 DOI: 10.1038/s41598-020-77034-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Accepted: 11/03/2020] [Indexed: 12/19/2022] Open
Abstract
The prevention of age-related cognitive decline and dementia is becoming a high priority because of the rapid growth of aging populations. We have previously shown that hop bitter acids such as iso-α-acids (IAAs) and matured hop bitter acids (MHBAs) activate the vagus nerve and improve memory impairment. Moreover, supplements with MHBAs were shown to improve memory retrieval in older adults. However, the underlying mechanisms have not been entirely elucidated. We aimed to investigate the effects of MHBAs and the common β-tricarbonyl moiety on memory impairment induced by the activation of microglia and the loss of the noradrenergic system. MHBAs and a model compound with β-tricarbonyl moiety were administered to LPS-inoculated mice and 5 × FAD Alzheimer’s disease (AD) model mice, following the evaluation in behavioral tests and microglial activation. To evaluate the association of noradrenaline with MHBAs effects, mice treated with N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), a noradrenergic neurotoxin that selectively damages noradrenergic projections from the locus coeruleus, were subjected to the behavioral evaluation. MHBAs reduced brain inflammation and improved LPS-induced memory impairment. A model compound possessing the β-tricarbonyl moiety improved the LPS-induced memory impairment and neuronal loss via the vagus nerve. Additionally, the protective effects of MHBAs on memory impairment were attenuated by noradrenaline depletion using DSP-4. MHBAs suppressed the activation of microglia and improved the memory impairment in 5 × FAD mice, which was also attenuated by noradrenaline depletion. Treatment with MHBAs increased cholecystokinin production from the intestinal cells. Generally, cholecystokinin activates the vagal nerve, which stimulate the noradrenergic neuron in the locus ceruleus. Taken together, our results reveal that food ingredients such as hop bitter acids with a β-tricarbonyl moiety suppress microglial activation and improve memory impairment induced by inflammation or AD pathology via the activation of the gut-brain axis and noradrenergic system. Supplements with hop bitter acids, including MHBAs, might be a novel approach for the prevention of cognitive decline and dementia.
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Affiliation(s)
- Yasuhisa Ano
- Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo, 113-8657, Japan. .,Kirin Central Research Institute, Kirin Holdings Company Ltd, 1-13-5 Fukuura Kanazawa-ku, Yokohama-shi, Kanagawa, 236-0004, Japan.
| | - Rena Ohya
- Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo, 113-8657, Japan.,Kirin Central Research Institute, Kirin Holdings Company Ltd, 1-13-5 Fukuura Kanazawa-ku, Yokohama-shi, Kanagawa, 236-0004, Japan
| | - Takahiro Yamazaki
- Kirin Central Research Institute, Kirin Holdings Company Ltd, 1-13-5 Fukuura Kanazawa-ku, Yokohama-shi, Kanagawa, 236-0004, Japan
| | - Chika Takahashi
- Kirin Central Research Institute, Kirin Holdings Company Ltd, 1-13-5 Fukuura Kanazawa-ku, Yokohama-shi, Kanagawa, 236-0004, Japan
| | - Yoshimasa Taniguchi
- Kirin Central Research Institute, Kirin Holdings Company Ltd, 1-13-5 Fukuura Kanazawa-ku, Yokohama-shi, Kanagawa, 236-0004, Japan
| | - Keiji Kondo
- Kirin Central Research Institute, Kirin Holdings Company Ltd, 1-13-5 Fukuura Kanazawa-ku, Yokohama-shi, Kanagawa, 236-0004, Japan
| | | | - Kazuyuki Uchida
- Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo, 113-8657, Japan
| | - Hiroyuki Nakayama
- Laboratory of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo, 113-8657, Japan
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4
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Alkan I, Altunkaynak BZ, Kivrak EG, Kaplan AA, Arslan G. Is vagal stimulation or inhibition benefit on the regulation of the stomach brain axis in obesity? Nutr Neurosci 2020; 25:758-770. [PMID: 33034260 DOI: 10.1080/1028415x.2020.1809875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Objective: Possible effects of the vagus inhibition and stimulation on the hypothalamic nuclei, myenteric plexes and the vagus nerve were investigated.Methods: The female rats divided to the inhibition (INH), stimulation (STI) and, sham (SHAM) groups were fed with high fat diet (including 40% of energy from animal fat). After nine weeks, the rats were allowed to recover for 4 weeks in INH group. In STI group, the left vagus nerve stimulated (30 Hz/500 msn/30 sec.) starting 2nd post operative day for 5 minutes during 4 weeks. Healthy female rats used as control (CONT). Then, tissue samples were analyzed by biochemical, histological and stereological methods.Results: The mean number of the neurons in the arcuate nucleus of the INH group was significantly less; but, that is significantly more in the STI group compared to the other groups. The neuronal density of ventromedial nucleus in the STI group was higher; while the density in the INH group was lower than the other groups. In the dorsomedial nucleus, neuron density of the INH group was lower than the other groups. In terms of the myenteric plexus volumes, that of the INH group was lowest. The myelinated axon number in the INH group was significantly highest. The myelin sheath thickness and axon area of the INH group was significantly lower than the other groups.Discussion: The results of the study show that the vagal inhibition is more effective than the vagal stimulation on the weight loss in the obesity.
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Affiliation(s)
- Işınsu Alkan
- Department of Histology and Embryology, Faculty of Medicine, İstanbul Okan University, İstanbul, Turkey
| | - Berrin Zuhal Altunkaynak
- Department of Histology and Embryology, Faculty of Medicine, İstanbul Okan University, İstanbul, Turkey
| | - Elfide Gizem Kivrak
- Department of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Arife Ahsen Kaplan
- Department of Histology and Embryology, Faculty of Medicine, Medipol University, Istanbul, Turkey
| | - Gülay Arslan
- Department of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
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5
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Suarez AN, Hsu TM, Liu CM, Noble EE, Cortella AM, Nakamoto EM, Hahn JD, de Lartigue G, Kanoski SE. Gut vagal sensory signaling regulates hippocampus function through multi-order pathways. Nat Commun 2018; 9:2181. [PMID: 29872139 PMCID: PMC5988686 DOI: 10.1038/s41467-018-04639-1] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 05/11/2018] [Indexed: 01/10/2023] Open
Abstract
The vagus nerve is the primary means of neural communication between the gastrointestinal (GI) tract and the brain. Vagally mediated GI signals activate the hippocampus (HPC), a brain region classically linked with memory function. However, the endogenous relevance of GI-derived vagal HPC communication is unknown. Here we utilize a saporin (SAP)-based lesioning procedure to reveal that selective GI vagal sensory/afferent ablation in rats impairs HPC-dependent episodic and spatial memory, effects associated with reduced HPC neurotrophic and neurogenesis markers. To determine the neural pathways connecting the gut to the HPC, we utilize monosynaptic and multisynaptic virus-based tracing methods to identify the medial septum as a relay connecting the medial nucleus tractus solitarius (where GI vagal afferents synapse) to dorsal HPC glutamatergic neurons. We conclude that endogenous GI-derived vagal sensory signaling promotes HPC-dependent memory function via a multi-order brainstem–septal pathway, thereby identifying a previously unknown role for the gut–brain axis in memory control. Feeding-relevant vagal signaling occurs between the gastrointestinal tract and the brain, but it is unclear if this pathway influences cognitive processes. This study shows that endogenous gastrointestinal derived vagal sensory signaling promotes hippocampal-dependent memory function via a multi-order brainstem–septal pathway.
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Affiliation(s)
- Andrea N Suarez
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Ted M Hsu
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California, USA.,Department of Psychology, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Clarissa M Liu
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA.,Neuroscience Graduate Program, University of Southern California, Los Angeles, California, USA
| | - Emily E Noble
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Alyssa M Cortella
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Emily M Nakamoto
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California, USA
| | - Joel D Hahn
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Guillaume de Lartigue
- The John B. Pierce Laboratory, New Haven, Connecticut, USA. .,Department of Cellular and Molecular Physiology, Yale Medical School, New Haven, Connecticut, USA.
| | - Scott E Kanoski
- Human and Evolutionary Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA. .,Neuroscience Graduate Program, University of Southern California, Los Angeles, California, USA. .,Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA.
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6
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Kim KS, Seeley RJ, Sandoval DA. Signalling from the periphery to the brain that regulates energy homeostasis. Nat Rev Neurosci 2018; 19:185-196. [DOI: 10.1038/nrn.2018.8] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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7
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Yang L, Chang CC, Sun Z, Madsen D, Zhu H, Padkjær SB, Wu X, Huang T, Hultman K, Paulsen SJ, Wang J, Bugge A, Frantzen JB, Nørgaard P, Jeppesen JF, Yang Z, Secher A, Chen H, Li X, John LM, Shan B, He Z, Gao X, Su J, Hansen KT, Yang W, Jørgensen SB. GFRAL is the receptor for GDF15 and is required for the anti-obesity effects of the ligand. Nat Med 2017; 23:1158-1166. [PMID: 28846099 DOI: 10.1038/nm.4394] [Citation(s) in RCA: 405] [Impact Index Per Article: 57.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/03/2017] [Indexed: 01/12/2023]
Abstract
Growth differentiation factor 15 (GDF15; also known as MIC-1) is a divergent member of the TGF-β superfamily and is associated with body-weight regulation in humans and rodents. However, the cognate receptor of GDF15 is unknown. Here we show that GDF15 binds specifically to GDNF family receptor α-like (GFRAL) with high affinity, and that GFRAL requires association with the coreceptor RET to elicit intracellular signaling in response to GDF15 stimulation. We also found that GDF15-mediated reductions in food intake and body weight of mice with obesity were abolished in GFRAL-knockout mice. We further found that GFRAL expression was limited to hindbrain neurons and not present in peripheral tissues, which suggests that GDF15-GFRAL-mediated regulation of food intake is by a central mechanism. Lastly, given that GDF15 did not increase energy expenditure in treated mice with obesity, the anti-obesity actions of the cytokine are likely driven primarily by a reduction in food intake.
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Affiliation(s)
- Linda Yang
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | - Chih-Chuan Chang
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | - Zhe Sun
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | | | - Haisun Zhu
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | | | - Xiaoai Wu
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | - Tao Huang
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | | | | | - Jishu Wang
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | - Anne Bugge
- Global Research, Novo Nordisk A/S, Maaloev, Denmark
| | | | - Per Nørgaard
- Global Research, Novo Nordisk A/S, Maaloev, Denmark
| | | | - Zhiru Yang
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | - Anna Secher
- Global Research, Novo Nordisk A/S, Maaloev, Denmark
| | - Haibin Chen
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | - Xun Li
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | | | - Bing Shan
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | - Zhenhua He
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | - Xiang Gao
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | - Jing Su
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
| | | | - Wei Yang
- Novo Nordisk Research Centre China, Novo Nordisk A/S, Beijing, China
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8
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Azab AN, Kaplanski J. Vagotomy attenuates the effect of lipopolysaccharide on body temperature of rats in a dose-dependent manner. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/09680519010070050301] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
There is a growing body of evidence suggesting that vagal afferents play a major role in peripheral-neural communication. This study was undertaken to determine whether a dose-dependent effect of lipopolysaccharide (LPS) on vagotomy-induced febrile unresponsiveness exists, and to examine the effect of vagotomy on LPS-induced increase in hypothalamic prostaglandin E2 (HT PGE2) production. Vagotomized and sham-operated rats were subjected to two experimental protocols. In the first, vagotomized and sham-operated rats were injected intraperitonealy with different doses of LPS (200, 500 and 1000 µg/kg) in order to examine the dose-dependent effect of LPS on the biphasic febrile response of the rats. In the second protocol, vagotomized and sham-operated rats were injected intraperitonealy with LPS (500 µg/kg). Two hours post injection, body temperature was measured, the rats were decapitated and blood was collected. Simultaneously, the rats' hypothalami were excised and incubated for 1 h in a Krebs-Henseleit buffer. Next, HT PGE2 was determined by radioimmunoassay. Vagotomy-induced gastric enlargement was then measured to examine the correlation between the magnitude of the enlargement and that of the vagotomy-related febrile unresponsiveness. It was found that vagotomized-induced febrile unresponsiveness is a dose-dependent effect. Subdiaphragmatic resection of the vagus prevented the biphasic febrile response caused by the lowest dose (200 µg/kg) of LPS, whereas the highest dose of LPS (1000 µg/kg) caused a similar biphasic febrile response in both vagotomized and sham-operated rats. Indeed, vagotomy attenuates LPS-induced increase in HT PGE2, and blocks the hypothermic phase of the febrile response. On the other hand, no correlation between gastric enlargement and febrile unresponsiveness was found. The results of the present study may cast further light on the crucial role of the vagus nerve as a peripheral-neural pathway in the mediation of the febrile response.
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Affiliation(s)
- Abed N. Azab
- Department of Clinical Pharmacology, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Jacob Kaplanski
- Department of Clinical Pharmacology, Ben-Gurion University of the Negev, Beer-Sheva, Israel,
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9
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Pasantes-Morales H. Channels and Volume Changes in the Life and Death of the Cell. Mol Pharmacol 2016; 90:358-70. [PMID: 27358231 DOI: 10.1124/mol.116.104158] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/22/2016] [Indexed: 12/11/2022] Open
Abstract
Volume changes deviating from original cell volume represent a major challenge for cellular homeostasis. Cell volume may be altered either by variations in the external osmolarity or by disturbances in the transmembrane ion gradients that generate an osmotic imbalance. Cells respond to anisotonicity-induced volume changes by active regulatory mechanisms that modify the intracellular/extracellular concentrations of K(+), Cl(-), Na(+), and organic osmolytes in the direction necessary to reestablish the osmotic equilibrium. Corrective osmolyte fluxes permeate across channels that have a relevant role in cell volume regulation. Channels also participate as causal actors in necrotic swelling and apoptotic volume decrease. This is an overview of the types of channels involved in either corrective or pathologic changes in cell volume. The review also underlines the contribution of transient receptor potential (TRP) channels, notably TRPV4, in volume regulation after swelling and describes the role of other TRPs in volume changes linked to apoptosis and necrosis. Lastly we discuss findings showing that multimers derived from LRRC8A (leucine-rich repeat containing 8A) gene are structural components of the volume-regulated Cl(-) channel (VRAC), and we underline the intriguing possibility that different heteromer combinations comprise channels with different intrinsic properties that allow permeation of the heterogenous group of molecules acting as organic osmolytes.
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Affiliation(s)
- Herminia Pasantes-Morales
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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10
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Role of gastrointestinal hormones in feeding behavior and obesity treatment. J Gastroenterol 2016; 51:93-103. [PMID: 26346735 DOI: 10.1007/s00535-015-1118-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 08/20/2015] [Indexed: 02/04/2023]
Abstract
Food intake regulation is generally evaluated by many aspects consisting of complex mechanisms, including homeostatic regulatory mechanism, which is based on negative feedback, and hedonic regulatory mechanism, which is driven by a reward system. One important aspect of food intake regulation is the peripheral hormones that are secreted from the gastrointestinal tract. These hormones are secreted from enteroendocrine cells as feedback to nutrient and energy intake, and will communicate with the brain directly or via the vagus nerve. Gastrointestinal hormones are very crucial in maintaining a steady body weight, despite variations in nutrient intake and energy expenditure. In this review, we provide an overview of the regulation of feeding behavior by gut hormones, and its role in obesity treatments.
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11
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12
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Lambert IH, Kristensen DM, Holm JB, Mortensen OH. Physiological role of taurine--from organism to organelle. Acta Physiol (Oxf) 2015; 213:191-212. [PMID: 25142161 DOI: 10.1111/apha.12365] [Citation(s) in RCA: 214] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 08/01/2014] [Accepted: 08/13/2014] [Indexed: 12/21/2022]
Abstract
Taurine is often referred to as a semi-essential amino acid as newborn mammals have a limited ability to synthesize taurine and have to rely on dietary supply. Taurine is not thought to be incorporated into proteins as no aminoacyl tRNA synthetase has yet been identified and is not oxidized in mammalian cells. However, taurine contributes significantly to the cellular pool of organic osmolytes and has accordingly been acknowledged for its role in cell volume restoration following osmotic perturbation. This review describes taurine homeostasis in cells and organelles with emphasis on taurine biophysics/membrane dynamics, regulation of transport proteins involved in active taurine uptake and passive taurine release as well as physiological processes, for example, development, lung function, mitochondrial function, antioxidative defence and apoptosis which seem to be affected by a shift in the expression of the taurine transporters and/or the cellular taurine content.
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Affiliation(s)
- I. H. Lambert
- Section of Cellular and Developmental Biology; Department of Biology; University of Copenhagen; Copenhagen Ø Denmark
| | - D. M. Kristensen
- Section of Genomics and Molecular Biomedicine; Department of Biology; University of Copenhagen; Copenhagen Denmark
- Cellular and Metabolic Research Section; Department of Biomedical Sciences; Panum Institute; University of Copenhagen; Copenhagen N Denmark
| | - J. B. Holm
- Section of Genomics and Molecular Biomedicine; Department of Biology; University of Copenhagen; Copenhagen Denmark
| | - O. H. Mortensen
- Cellular and Metabolic Research Section; Department of Biomedical Sciences; Panum Institute; University of Copenhagen; Copenhagen N Denmark
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13
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Sørensen BH, Thorsteinsdottir UA, Lambert IH. Acquired cisplatin resistance in human ovarian A2780 cancer cells correlates with shift in taurine homeostasis and ability to volume regulate. Am J Physiol Cell Physiol 2014; 307:C1071-80. [PMID: 25252947 DOI: 10.1152/ajpcell.00274.2014] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cisplatin resistance is a major challenge in the treatment of cancer and develops through reduced drug accumulation and an increased ability to avoid drug-induced cell damage, cell shrinkage, and hence initiation of apoptosis. Uptake and release of the semiessential amino acid taurine contribute to cell volume homeostasis, and taurine has been reported to have antiapoptotic effects. Here we find that volume-sensitive taurine release in cisplatin-sensitive [wild-type (WT)] human ovarian cancer A2780 cells is reduced in the presence of the phospholipase A2 inhibitor bromenol lactone, the 5-lipoxygenase (5-LO) inhibitor ETH 615-139, and the cysteine leukotriene receptor 1 (CysLT1) antagonist zafirlukast and impaired by the anion channel blocker DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonate). Comparing WT and cisplatin-resistant (RES) A2780 cells we also find that evasion of cisplatin-induced cell death in RES A2780 cells correlates with an increased accumulation of taurine, due to an increased taurine uptake and a concomitant impairment of the volume-sensitive taurine release pathway, as well an inability to reduce cell volume after osmotic cell swelling. Downregulation of volume-sensitive taurine release in RES A2780 cells correlates with reduced expression of the leucine-rich repeat-containing protein 8A (LRRC8A). Furthermore, acute (18 h) exposure to cisplatin (5-10 μM) increases taurine release and LRRC8A expression in WT A2780 cells whereas cisplatin has no effect on LRRC8A expression in RES A2780 cells. It is suggested that shift in LRRC8A activity can be used as biomarker for apoptotic progress and acquirement of drug resistance.
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Affiliation(s)
- Belinda Halling Sørensen
- Department of Biology, Section of Cellular and Developmental Biology, The August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Unnur Arna Thorsteinsdottir
- Department of Biology, Section of Cellular and Developmental Biology, The August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Ian Henry Lambert
- Department of Biology, Section of Cellular and Developmental Biology, The August Krogh Building, University of Copenhagen, Copenhagen, Denmark
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14
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Schwartz GJ, Zeltser LM. Functional organization of neuronal and humoral signals regulating feeding behavior. Annu Rev Nutr 2013; 33:1-21. [PMID: 23642202 DOI: 10.1146/annurev-nutr-071812-161125] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Energy homeostasis--ensuring that energy availability matches energy requirements--is essential for survival. One way that energy balance is achieved is through coordinated action of neural and neuroendocrine feeding circuits, which promote energy intake when energy supply is limited. Feeding behavior engages multiple somatic and visceral tissues distributed throughout the body--contraction of skeletal and smooth muscles in the head and along the upper digestive tract required to consume and digest food, as well as stimulation of endocrine and exocrine secretions from a wide range of organs. Accordingly, neurons that contribute to feeding behaviors are localized to central, peripheral, and enteric nervous systems. To promote energy balance, feeding circuits must be able to identify and respond to energy requirements, as well as the amount of energy available from internal and external sources, and then direct appropriate coordinated responses throughout the body.
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Affiliation(s)
- Gary J Schwartz
- Department of Medicine, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA
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Kim GW, Lin JE, Valentino MA, Colon-Gonzalez F, Waldman SA. Regulation of appetite to treat obesity. Expert Rev Clin Pharmacol 2012; 4:243-59. [PMID: 21666781 DOI: 10.1586/ecp.11.3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Obesity has escalated into a pandemic over the past few decades. In turn, research efforts have sought to elucidate the molecular mechanisms underlying the regulation of energy balance. A host of endogenous mediators regulate appetite and metabolism, and thereby control both short- and long-term energy balance. These mediators, which include gut, pancreatic and adipose neuropeptides, have been targeted in the development of anti-obesity pharmacotherapy, with the goal of amplifying anorexigenic and lipolytic signaling or blocking orexigenic and lipogenic signaling. This article presents the efficacy and safety of these anti-obesity drugs.
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Affiliation(s)
- Gilbert W Kim
- Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, 132 S. 10th Street, 1170 Main, Philadelphia, PA 19107, USA
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16
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McAllan L, Cotter PD, Roche HM, Korpela R, Nilaweera KN. Impact of leucine on energy balance. J Physiol Biochem 2012; 69:155-63. [PMID: 22535285 DOI: 10.1007/s13105-012-0170-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 04/10/2012] [Indexed: 12/14/2022]
Abstract
Body weight is determined by the balance between energy intake and energy expenditure. When energy intake exceeds energy expenditure, the surplus energy is stored as fat in the adipose tissue, which causes its expansion and may even lead to the development of obesity. Thus, there is a growing interest to develop dietary interventions that could reduce the current obesity epidemic. In this regard, data from a number of in vivo and in vitro studies suggest that the branched-chain amino acid leucine influences energy balance. However, this has not been consistently reported. Here, we review the literature related to the effects of leucine on energy intake, energy expenditure and lipid metabolism as well as its effects on the cellular activity in the brain (hypothalamus) and in peripheral tissues (gastro-intestinal tract, adipose tissue, liver and muscle) regulating the above physiological processes. Moreover, we discuss how obesity may influence the actions of this amino acid.
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Affiliation(s)
- Liam McAllan
- Teagasc Food Research Centre, Moorepark, Fermoy, Cork, Ireland
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17
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Amin A, Murphy KG. Nutritional sensing and its utility in treating obesity. Expert Rev Endocrinol Metab 2012; 7:209-221. [PMID: 30764012 DOI: 10.1586/eem.12.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Obesity remains a major worldwide health problem, with current medical treatments being poorly effective. Nutrient sensing allows organs such as the GI tract and the brain to recognize and respond to fuel substrates such as carbohydrates, protein and fats. Specialized neural and hormonal pathways exist to facilitate and regulate these chemosensory mechanisms. Manipulation of factors involved in either central or peripheral chemosensory pathways may provide possible targets for the manipulation of appetite. However, further research is required to assess the utility of this approach to developing novel anti-obesity agents.
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Affiliation(s)
- Anjali Amin
- a Section of Investigative Medicine, Faculty of Medicine, Imperial College London, 6th Floor, Commonwealth Building, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Kevin G Murphy
- b Section of Investigative Medicine, Faculty of Medicine, Imperial College London, 6th Floor, Commonwealth Building, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK.
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Keung W, Man RYK. Circulating sex hormones modulate vascular contractions and acute response to 17β-estradiol in rat mesenteric arteries. Pharmacology 2011; 88:55-64. [PMID: 21791946 DOI: 10.1159/000329426] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 05/09/2011] [Indexed: 11/19/2022]
Abstract
AIMS We investigated how modification of levels of the sex hormones 17β-estradiol and testosterone affects vascular contraction and nongenomic vascular effects of 17β-estradiol. METHODS Male and female rats were treated with vehicle, 17β-estradiol (25 μg/kg/day) or testosterone (1 mg/kg/day) for 14 consecutive days after sham gonadectomy or gonadectomy was performed. Isometric tensions were then measured from mesenteric arteries of each group of rats. RESULTS Contraction to phenylephrine was increased in mesenteric arteries from rats with or without gonadectomy treated with testosterone for 14 days compared to their intact controls. Contraction to phenylephrine was reduced in mesenteric arteries of rats with or without gonadectomy treated with 17β-estradiol for 14 days compared to their intact controls. Incubation of mesenteric arteries with 17β-estradiol (1 nmol/l) for 30 min reduced contraction to phenylephrine in mesenteric arteries of rats that were treated with testosterone for 14 days. This acute incubation of 17β-estradiol had no effect on arteries from rats that were treated with 17β-estradiol for 14 days. The acute effect of 17β-estradiol (1 nmol/l) is preserved in arteries without endothelium. CONCLUSION Our results suggest that 14 days' testosterone treatment enhances while 14 days' 17β-estradiol treatment suppresses contraction as well as the nongenomic effects of 17β-estradiol in the vascular smooth muscles.
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Affiliation(s)
- Wendy Keung
- Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, SAR, China.
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19
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Regulation of taurine homeostasis by protein kinase CK2 in mouse fibroblasts. Amino Acids 2010; 40:1091-106. [DOI: 10.1007/s00726-010-0732-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 08/23/2010] [Indexed: 12/26/2022]
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Villumsen KR, Duelund L, Lambert IH. Acute cholesterol depletion leads to net loss of the organic osmolyte taurine in Ehrlich Lettré tumor cells. Amino Acids 2010; 39:1521-36. [DOI: 10.1007/s00726-010-0621-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Accepted: 05/05/2010] [Indexed: 11/30/2022]
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21
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Xu X, Urban JPG, Tirlapur UK, Cui Z. Osmolarity effects on bovine articular chondrocytes during three-dimensional culture in alginate beads. Osteoarthritis Cartilage 2010; 18:433-9. [PMID: 19840877 DOI: 10.1016/j.joca.2009.10.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Revised: 09/30/2009] [Accepted: 09/05/2009] [Indexed: 02/02/2023]
Abstract
OBJECTIVE With the development of engineered cartilage, the determination of the appropriate culture conditions is vital in order to maximize extracellular matrix synthesis. As osmolarity could affect the fate of chondrocytes, the purpose of this study was to determine the effects of osmolarity on chondrocytes during relatively long-term culture. DESIGN Bovine articular chondrocytes were cultured in alginate beads in a biocarbonate free system at 280, 380 and 550 mOsm at pH 7.4 for up to 12 days, respectively. Cell volume, intracellular pH (pH(i)), cell number, glucosaminoglycan (GAG) and collagen retention were measured at day 5 and 12. Cell viability and volume were monitored over the 12 days of culture. RESULTS By day 5 and 12, compared to the cell volume at 380 mOsm, around 20% (P<0.01) swelling and 15% (P<0.05) shrinkage were observed when the cells were cultured at 280 and 550 mOsm. The pH(i) over the 12 days of culture varied with osmolarity of the culture medium. In comparison with fresh cells, pH(i) became slightly more acidic by 0.15 pH units at 280 mOsm at day 5. However, by day 12, an alkalization of pH(i), by 0.2 pH units, was noted. A higher proliferation rate was seen at 280 mOsm than at other osmolarities while less GAG was produced. CONCLUSIONS Chronic exposure to anisotonic conditions results in cell swelling at 280 mOsm and shrinkage at 550 mOsm. The osmolarity of 280 mOsm appears to encourage proliferation of chondrocytes, but inhibits matrix production.
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Affiliation(s)
- X Xu
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK
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22
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Chan YC, Leung FP, Wong WT, Tian XY, Yung LM, Lau CW, Tsang SY, Yao X, Chen ZY, Huang Y. Therapeutically relevant concentrations of raloxifene dilate pressurized rat resistance arteries via calcium-dependent endothelial nitric oxide synthase activation. Arterioscler Thromb Vasc Biol 2010; 30:992-9. [PMID: 20185791 DOI: 10.1161/atvbaha.110.203935] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Selective estrogen receptor modulators (SERMs) inhibit constriction of mammalian conduit arteries. However, it is unknown whether SERMs at therapeutically achievable concentrations could reduce vascular tone in resistance arteries. The present study aimed to examine roles of Ca(2+) influx in endothelium and endothelial nitric oxide synthase (eNOS) activation in dilatations induced by raloxifene, a second-generation SERM in myogenically active arteries. METHODS AND RESULTS Small mesenteric arteries from Sprague-Dawley rats were isolated and mounted in a pressure myograph for measurement of changes in vessel diameter. [Ca(2+)](i) images on native endothelial cells of intact arteries were determined by the fluorescence imaging technique, and phosphorylation of eNOS was assayed by Western blotting. Raloxifene (0.3 to 10 nmol/L) produced dilatations on established steady myogenic constriction. Female rat arteries dilated significantly more in response to raloxifene than male arteries. Raloxifene-induced dilatations of female arteries were blunted by N(G)-nitro-l-arginine methyl ester but unaffected by 1400W, charybdotoxin plus apamin, wortmannin, or LY294002. Raloxifene (3 nmol/L) triggered rises in endothelial cell [Ca(2+)](i) and increased eNOS phosphorylation at Ser1177. Both effects were greater in arteries from female rats than in arteries from male rats. Increases in endothelial cell [Ca(2+)](i) and in eNOS phosphorylation were prevented by removal of extracellular Ca(2+) ions. Finally, ICI 182,780 did not affect the raloxifene-stimulated rise in endothelial cell [Ca(2+)](i), eNOS phosphorylation, and vasodilatations. Chronic raloxifene treatment reduced myogenic constriction in arteries from female but not male rats. CONCLUSION Raloxifene at therapeutically relevant concentrations inhibits myogenic constriction by an NO-dependent mechanism that causally involves the elevated [Ca(2+)](i) in endothelial cells and subsequent eNOS activation. Raloxifene dilates resistance arteries more effectively in female rats, indicating its significant gender-related action on endothelial cells in microcirculation.
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Affiliation(s)
- Yau Chi Chan
- Institute of Vascular Medicine, Hong Kong, China
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Cheung GWC, Kokorovic A, Lam TKT. Upper intestinal lipids regulate energy and glucose homeostasis. Cell Mol Life Sci 2009; 66:3023-7. [PMID: 19513587 PMCID: PMC11115480 DOI: 10.1007/s00018-009-0062-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 05/25/2009] [Accepted: 05/27/2009] [Indexed: 10/20/2022]
Abstract
Upon the entry of nutrients into the small intestine, nutrient sensing mechanisms are activated to allow the body to adapt appropriately to the incoming nutrients. To date, mounting evidence points to the existence of an upper intestinal lipid-induced gut-brain neuronal axis to regulate energy homeostasis. Moreover, a recent discovery has also revealed an upper intestinal lipid-induced gut-brain-liver neuronal axis involved in the regulation of glucose homeostasis. In this mini-review, we will focus on the mechanisms underlying the activation of these respective neuronal axes by upper intestinal lipids.
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Affiliation(s)
- Grace W. C. Cheung
- Department of Physiology, University of Toronto, Toronto, M5S 1A8 Canada
- Toronto General Research Institute, University Health Network, Toronto, M5G 1L7 Canada
| | - Andrea Kokorovic
- Department of Physiology, University of Toronto, Toronto, M5S 1A8 Canada
- Toronto General Research Institute, University Health Network, Toronto, M5G 1L7 Canada
| | - Tony K. T. Lam
- Department of Physiology, University of Toronto, Toronto, M5S 1A8 Canada
- Department of Medicine, University of Toronto, Toronto, M5S 1A8 Canada
- Toronto General Research Institute, University Health Network, Toronto, M5G 1L7 Canada
- MaRS Centre, Toronto Medical Discovery Tower, Room 10-706, 101 College Street, Toronto, ON M5G 1L7 Canada
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Al Malty AM, Petrofsky J, Akhavan S. Aging in Women: The Effect of Menopause on Skin Blood Flow and the Response to Electrical Stimulation. PHYSICAL & OCCUPATIONAL THERAPY IN GERIATRICS 2009. [DOI: 10.1080/02703180802335659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Shennan DB. Swelling-induced taurine transport: relationship with chloride channels, anion-exchangers and other swelling-activated transport pathways. Cell Physiol Biochem 2008; 21:15-28. [PMID: 18209468 DOI: 10.1159/000113743] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2007] [Indexed: 11/19/2022] Open
Abstract
Cells have to regulate their volume in order to survive. Moreover, it is now evident that cell volume per se and the membrane transport processes which regulate it, comprise an important signalling unit. For example, macromolecular synthesis, apoptosis, cell growth and hormone secretion are all influenced by the cellular hydration state. Therefore, a thorough understanding of volume-activated transport processes could lead to new strategies being developed to control the function and growth of both normal and cancerous cells. Cell swelling stimulates the release of ions such as K(+) and Cl(-) together with organic osmolytes, especially the beta-amino acid taurine. Despite being the subject of intense research interest, the nature of the volume-activated taurine efflux pathway is still a matter of controversy. On the one hand it has been suggested that osmosensitive taurine efflux utilizes volume-sensitive anion channels whereas on the other it has been proposed that the band 3 anion-exchanger is a swelling-induced taurine efflux pathway. This article reviews the evidence for and against a role of anion channels and exchangers in osmosensitive taurine transport. Furthermore, the distinct possibility that neither pathway is involved in taurine transport is highlighted. The putative relationship between swelling-induced taurine transport and volume-activated anionic amino acid, alpha-neutral amino acid and K(+) transport is also examined.
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Affiliation(s)
- David B Shennan
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, Scotland, UK.
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27
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Hillebrand U, Hausberg M, Lang D, Stock C, Riethmüller C, Callies C, Büssemaker E. How steroid hormones act on the endothelium—insights by atomic force microscopy. Pflugers Arch 2008; 456:51-60. [DOI: 10.1007/s00424-007-0411-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Accepted: 11/20/2007] [Indexed: 02/05/2023]
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Williams DL, Schwartz MW, Bastian LS, Blevins JE, Baskin DG. Immunocytochemistry and laser capture microdissection for real-time quantitative PCR identify hindbrain neurons activated by interaction between leptin and cholecystokinin. J Histochem Cytochem 2007; 56:285-93. [PMID: 18040081 DOI: 10.1369/jhc.7a7331.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Current evidence suggests that leptin reduces food intake in part by enhancing the hindbrain neuronal response to meal-related gastrointestinal signals, including cholecystokinin (CCK), but the phenotypes of the relevant cells are not known. To identify neurons that participate in this interaction in the rat nucleus of the solitary tract (NTS), we induced c-Fos gene expression in NTS neurons with leptin and CCK. We focused on NTS catecholamine neurons because these cells have been implicated in the feeding response to CCK. Hindbrain sections from rats that received CCK with or without leptin pretreatment were immunostained for c-Fos and tyrosine hydroxylase (TH) by a double immunofluorescence procedure. Leptin pretreatment increased the number of NTS cells expressing c-Fos-like immunoreactivity (cFLI) 3-fold relative to CCK alone, but the number of TH-positive cells with cFLI was increased 6-fold. Next, cells detected by immunofluorescence for TH were collected by laser capture microdissection and pooled for real-time quantitative PCR of c-Fos mRNA. Here, neither le0ptin nor CCK alone affected the relative amount of mRNA in the TH cell-enriched samples, but leptin plus CCK substantially increased c-Fos mRNA content. These histochemical findings identify hindbrain catecholamine cells as potential mediators of the interaction between leptin and CCK.
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Affiliation(s)
- Diana L Williams
- Division of Metabolism, Endocrinology, and Nutrition, Department of Medicine, University of Washington, Seattle, Washington, USA.
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29
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Leung SWS, Teoh H, Keung W, Man RYK. Non-genomic vascular actions of female sex hormones: physiological implications and signalling pathways. Clin Exp Pharmacol Physiol 2007; 34:822-6. [PMID: 17600565 DOI: 10.1111/j.1440-1681.2007.04686.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Epidemiological studies indicate a lower incidence of coronary heart disease in premenopausal women compared with age-matched men and post-menopausal women. Accumulating evidence suggests that this cardiovascular protection observed in premenopausal women is at least partially attributed to the direct action of oestrogens on the vascular system. 2. Research focused on vascular actions of 17beta-oestradiol indicates that this female sex hormone favourably modulates vascular reactivity at physiological concentrations. The vascular actions of 17beta-oestradiol appear independent of its genomic actions. Both endothelium-dependent and -independent signalling cascades have been implicated in the vascular effects of 17beta-oestradiol. 3. However, clinical trials on hormone-replacement therapy argue against a role of oestrogens in preventing the development of coronary heart disease. Supplementation with oestrogen is also complicated with the increased risk of breast and endometrial cancer. Hence, a better understanding of the vascular actions of 17beta-oestradiol will serve to enhance our understanding of its role in coronary heart disease.
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Affiliation(s)
- Susan W S Leung
- Department of Pharmacology, Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
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Tranberg M, Abbas AK, Sandberg M. In Vitro Studies on the Putative Function of N-acetylaspartate as an Osmoregulator. Neurochem Res 2007; 32:1248-55. [PMID: 17401659 DOI: 10.1007/s11064-007-9300-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Accepted: 01/30/2007] [Indexed: 10/23/2022]
Abstract
Efflux and tissue content of N-acetylaspartate (NAA) and amino acids were evaluated from cultured and acutely prepared hippocampal slices in response to changes in osmolarity. The osmoregulator taurine, but not NAA, was lost from both types of slices after moderate reductions in extracellular osmolarity (-60 mOsm) for 10-48 h. Hypoosmotic shock (-166 mOsm) for 5 min resulted in unselective efflux of several amino acids from acutely prepared slices. Notably, the efflux of taurine, but not NAA, was prominent also after the shock. Efflux of NAA was markedly enhanced by NMDA and high K(+), in particular after the stimulation period. The high K(+)-mediated efflux was decreased by high extracellular osmolarity and a NMDA-receptor antagonist. The results indicate that NAA efflux can be induced by a sudden non-physiological decrease in extracellular osmolarity but not by prolonged more moderate changes in osmolarity. The mechanisms behind the efflux of NAA by high K(+) are complex and may involve both swelling and activation of NMDA-receptors.
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Affiliation(s)
- Mattias Tranberg
- Institute of Neuroscience and Physiology, Department of Physiology, Göteborg University, Göteborg, Sweden
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Lambert IH, Pedersen SF. Multiple PLA2 isoforms regulate taurine release in NIH3T3 mouse fibroblasts. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 583:99-108. [PMID: 17153593 DOI: 10.1007/978-0-387-33504-9_10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Affiliation(s)
- Ian Henry Lambert
- Dept. of Biochemistry, Institute for Molecular Biology and Physiology, The August Krogh Building, 13, Universitetsparken, DK-2100 Copenhagen, Denmark.
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Abstract
Despite substantial fluctuations in daily food intake, animals maintain a remarkably stable body weight, because overall caloric ingestion and expenditure are exquisitely matched over long periods of time, through the process of energy homeostasis. The brain receives hormonal, neural, and metabolic signals pertaining to body-energy status and, in response to these inputs, coordinates adaptive alterations of energy intake and expenditure. To regulate food consumption, the brain must modulate appetite, and the core of appetite regulation lies in the gut-brain axis. This Review summarizes current knowledge regarding the neuroendocrine regulation of food intake by the gastrointestinal system, focusing on gastric distention, intestinal and pancreatic satiation peptides, and the orexigenic gastric hormone ghrelin. We highlight mechanisms governing nutrient sensing and peptide secretion by enteroendocrine cells, including novel taste-like pathways. The increasingly nuanced understanding of the mechanisms mediating gut-peptide regulation and action provides promising targets for new strategies to combat obesity and diabetes.
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Affiliation(s)
- David E Cummings
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Veterans Affairs Puget Sound Health Care System, Seattle, Washington 98108, USA.
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Michel S, Becskei C, Erguven E, Lutz TA, Riediger T. Diet-derived nutrients modulate the effects of amylin on c-Fos expression in the area postrema and on food intake. Neuroendocrinology 2007; 86:124-35. [PMID: 17703089 DOI: 10.1159/000107579] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 07/13/2007] [Indexed: 11/19/2022]
Abstract
The pancreatic hormone amylin decreases food intake via activation of area postrema (AP) neurons. We investigated whether amylin's potency to reduce food intake and to induce c-Fos expression in the AP/nucleus of the solitary tract region is affected by the feeding conditions and specifically by the macronutrient composition of the diet. Whereas a low dose of amylin (5 microg/kg s.c.) induced very little c-Fos expression in ad libitum chow fed rats, it caused a strong c-Fos expression in 24-hour food-deprived rats and in rats that received a nutrient-deficient non-caloric mash (NCM; vanilla-flavoured cellulose) 24 h before injection. To reveal the contribution of single nutrients to the low c-Fos expression after chow feeding, amylin-induced c-Fos was analyzed after feeding NCM that was selectively supplemented with glucose, fat (lard), or protein (casein), matching the intake of these nutrients of chow-fed rats. While the rats fed NCM supplemented with glucose or fat displayed an equally strong amylin-induced activation as fasted rats or rats fed plain NCM, a significantly lower c-Fos expression was observed in rats fed a protein-supplemented NCM or a NCM containing all three nutrients. In line with this lower activation, the same dose of amylin failed to reduce food intake in NCM/protein-fed rats, while amylin caused a reduction in feeding when animals received NCM, NCM/glucose, or NCM/fat. Interestingly, amylin effectively reduced food intake in ad libitum chow fed rats despite the low level of amylin-induced c-Fos expression in the AP under these conditions. We conclude that the anorectic potential of amylin may be attenuated by diet-derived proteins, whereas this effect appears to be overridden when the amount of carbohydrates/fat is high relative to the protein content, such as, e.g., in standard chow.
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Affiliation(s)
- Signe Michel
- Institute of Veterinary Physiology, University of Zürich, Zürich, Switzerland
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Heijboer AC, Pijl H, Van den Hoek AM, Havekes LM, Romijn JA, Corssmit EPM. Gut-brain axis: regulation of glucose metabolism. J Neuroendocrinol 2006; 18:883-94. [PMID: 17076764 DOI: 10.1111/j.1365-2826.2006.01492.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Obesity and type II diabetes mellitus have reached epidemic proportions. From this perspective, knowledge about the regulation of satiety and food intake is more important than ever. The gut releases several peptides upon feeding, which affect hypothalamic pathways involved in the regulation of satiety and metabolism. Within the hypothalamus, there are complex interactions between many nuclei of which the arcuate nucleus is considered as one of the most important hypothalamic centres that regulates food intake. The neuropeptides, which are present in the hypothalamus and are involved in regulating food intake, also play a key role in regulating glucose metabolism and energy expenditure. In synchrony with the effects of those neuropeptides, gastrointestinal hormones also affect glucose metabolism and energy expenditure. In this review, the effects of the gastrointestinal hormones ghrelin, cholecystokinin, peptide YY, glucagon-like peptide, oxyntomodulin and gastric inhibitory polypeptide on glucose and energy metabolism are reviewed. These gut hormones affect glucose metabolism at different levels: by altering food intake and body weight, and thereby insulin sensitivity; by affecting gastric delay and gut motility, and thereby meal-related fluctuations in glucose levels; by affecting insulin secretion, and thereby plasma glucose levels, and by affecting tissue specific insulin sensitivity of glucose metabolism. These observations point to the notion of a major role of the gut-brain axis in the integrative physiology of whole body fuel metabolism.
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Affiliation(s)
- A C Heijboer
- Department of Endocrinology and Metabolic Diseases, Leiden University Medical Center, Leiden, The Netherlands
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Abstract
Ingestive behavior is a complex product of distributed central control systems that respond to a diverse array of internal and external sensory stimuli. Relatively little is known regarding the pathways and mechanisms by which relevant signals are conveyed to the neural circuits that ultimately control ingestive motor output. This report summarizes findings regarding the postnatal development of descending hypothalamic inputs to the hindbrain dorsal vagal complex (DVC). Evidence accumulated primarily in rats indicates that descending neural projections from the hypothalamus to the DVC are both structurally and functionally immature at birth. The progressive postnatal maturation of these projections occurs in parallel with newly emerging physiological and behavioral responsiveness to treatments and stimuli that affect food intake in adults. Thus, the postnatal emergence of new feeding controls may reflect the emerging access of these controls to DVC neural circuits.
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Affiliation(s)
- Linda Rinaman
- Department of Neuroscience, 446 Crawford Hall, University of Pittsburgh, PA 15260, USA.
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Macia L, Viltart O, Verwaerde C, Delacre M, Delanoye A, Grangette C, Wolowczuk I. Genes involved in obesity: Adipocytes, brain and microflora. GENES & NUTRITION 2006; 1:189-212. [PMID: 18850214 PMCID: PMC3454837 DOI: 10.1007/bf02829968] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The incidence of obesity and related metabolic disorders such as cardiovascular diseases and type 2 diabetes, are reaching worldwide epidemic proportions. It results from an imbalance between caloric intake and energy expenditure leading to excess energy storage, mostly due to genetic and environmental factors such as diet, food components and/or way of life. It is known since long that this balance is maintained to equilibrium by multiple mechanisms allowing the brain to sense the nutritional status of the body and adapt behavioral and metabolic responses to changes in fuel availability. In this review, we summarize selected aspects of the regulation of energy homeostasis, prevalently highlighting the complex relationships existing between the white adipose tissue, the central nervous system, the endogenous microbiota, and nutrition. We first describe how both the formation and functionality of adipose cells are strongly modulated by the diet before summarizing where and how the central nervous system integrates peripheral signals from the adipose tissue and/or the gastro-intestinal tract. Finally, after a short description of the intestinal commensal flora, rangingfrom its composition to its importance in immune surveillance, we enlarge the discussion on how nutrition modified this perfectly well-balanced ecosystem.
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Affiliation(s)
- L. Macia
- Laboratoire de Neuro-Immuno-Endocrinologie, Institut Pasteur de Lille /1 FR 142, 1, rue A. Calmette, BP 447, 59019 Lille cedex, France
| | - O. Viltart
- Unité de Neurosciences et de Physiologie Adaptatives SN4, Université de Lille I, 59655 Villeneuve d’Ascq, France
| | - C. Verwaerde
- Laboratoire de Neuro-Immuno-Endocrinologie, Institut Pasteur de Lille /1 FR 142, 1, rue A. Calmette, BP 447, 59019 Lille cedex, France
| | - M. Delacre
- Laboratoire de Neuro-Immuno-Endocrinologie, Institut Pasteur de Lille /1 FR 142, 1, rue A. Calmette, BP 447, 59019 Lille cedex, France
| | - A. Delanoye
- Laboratoire de Neuro-Immuno-Endocrinologie, Institut Pasteur de Lille /1 FR 142, 1, rue A. Calmette, BP 447, 59019 Lille cedex, France
| | - C. Grangette
- Bactéries Lactiques et Immunité des Muqueuses, Institut Pasteur de Lille / Institut de Biologie de Lille, 1, rue A. Calmette, BP 447, 59019 Lille cedex, France
| | - I. Wolowczuk
- Laboratoire de Neuro-Immuno-Endocrinologie, Institut Pasteur de Lille /1 FR 142, 1, rue A. Calmette, BP 447, 59019 Lille cedex, France
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Lambert IH, Pedersen SF, Poulsen KA. Activation of PLA2 isoforms by cell swelling and ischaemia/hypoxia. Acta Physiol (Oxf) 2006; 187:75-85. [PMID: 16734744 DOI: 10.1111/j.1748-1716.2006.01557.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Phospholipase A2 (PLA2) activity is increased in mammalian cells in response to numerous stimuli such as osmotic challenge, oxidative stress and exposure to allergens. The increased PLA2 activity is seen as an increased release of free, polyunsaturated fatty acids, e.g. arachidonic acid and membrane-bound lysophospholipids. Even though arachidonic acid acts as a second messenger in its own most mammalian cells seem to rely on oxidation of the fatty acid into highly potent second messengers via, e.g. cytochrome P450, the cyclo-oxygenase, or the lipoxygenase systems for downstream signalling. Here, we review data that illustrates that stress-induced PLA2 activity involves various PLA2 subtypes and that the PLA2 in question is determined by the cell type and the physiological stress condition.
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Affiliation(s)
- I H Lambert
- Institute for Molecular Biology and Physiology, The August Krogh Building, Universitetsparken, Copenhagen Ø, Denmark.
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Abstract
Appetite regulation is part of a feedback system that controls the energy balance, involving a complex interplay of hunger and satiety signals, produced in the hypothalamus as well as in peripheral organs. Hunger signals may be generated in peripheral organs (e.g. ghrelin) but most of them are expressed in the hypothalamus (neuropeptide Y, orexins, agouti-related peptide, melanin concentrating hormone, endogenous opiates and dopamine) and are expressed during situations of energy deficiency. Some satiety signals, such as cholecystokinin, glucagon-like peptide 1, peptide YY and enterostatin are released from the digestive tract in response to food intake. Others, such as leptin and insulin, are mobilized in response to perturbations in the nutritional state. Still others are generated in neurones of the hypothalamus (alpha-melanocyte-stimulating hormone and serotonin). Satiety signals act by inhibiting the expression of hunger signals and/or by blunting their effect. Palatable food, i.e. food rich in fat and sugar, up-regulates the expression of hunger signals and satiety signals, at the same time blunting the response to satiety signals and activating the reward system. Hence, palatable food offsets normal appetite regulation, which may explain the increasing problem of obesity worldwide.
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Yeung CH, Barfield JP, Cooper TG. The role of anion channels and Ca2+ in addition to K+ channels in the physiological volume regulation of murine spermatozoa. Mol Reprod Dev 2005; 71:368-79. [PMID: 15803461 DOI: 10.1002/mrd.20261] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Studies in the human, transgenic mice, and cattle indicate that sperm cell volume regulation plays an important role in male fertility as spermatozoa encounter a hypo-osmotic challenge upon ejaculation into the female tract. Physiological regulatory volume decrease (RVD) was examined using flow cytometry in murine sperm released into incubation medium mimicking uterine osmolality and including putative channel inhibitors. The involvement of K+ channels was indicated by the recovery of volume regulation by the K+ ionophore valinomycin in defective sperm from infertile transgenic mice, and from blockage of RVD by quinine in normal sperm. However, in neither case was the recovery complete. The involvement of volume-sensitive osmolyte and anion channels (VSOAC) were investigated using blockers effective in other cell types. NPPB (5-nitro-2(3-phenylpropylamino) benzoic acid) and tamoxifen inhibited RVD but SITS (4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulphonic acid) at 0.4 and 1 mM had no effect whereas DIDS (di-isothiocyanato-stilbene-2,2'-disulphonic acid) at 1 mM enhanced RVD. Verapamil, but not another P-glycoprotein antagonist cyclosporin, caused sperm swelling which persisted in the presence of valinomycin, in Ca2+-free medium and in the presence of thapsigargin, but swelling was abolished by the Ca2+ ionophore A23187. Nifedipine was slightly effective in blocking RVD. Analysis by Western blotting failed to reveal ClC-2 and ClC-3 members of the chloride channel family in murine or rat sperm proteins despite signal bands in positive tissue controls. These findings implicate the involvement of some unidentified VSOAC in sperm volume regulation, which is probably Ca+-dependent.
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Affiliation(s)
- Ching-Hei Yeung
- Institute of Reproductive Medicine of the University Clinic, Münster, Germany.
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Sun H, Mayhan WG. Sex difference in nitric oxide synthase-dependent dilatation of cerebral arterioles during long-term alcohol consumption. Alcohol Clin Exp Res 2005; 29:430-6. [PMID: 15770119 DOI: 10.1097/01.alc.0000156117.87892.22] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Although long-term alcohol consumption impairs both endothelial nitric oxide synthase (NOS) (eNOS)-dependent and neuronal NOS (nNOS)-dependent reactivity of cerebral arterioles in male rats, the influence of sex on alcohol consumption-induced impairment of NOS-dependent cerebral vasodilation has not been examined. Therefore, the authors' first goal was to determine whether long-term alcohol consumption alters eNOS-dependent and nNOS-dependent reactivity of pial arterioles in female rats. Their second goal was to examine potential mechanisms for impaired responses of pial arterioles during long-term alcohol consumption. METHODS Male and female rats were fed liquid diets with or without alcohol for 2-3 months. The authors measured the in vivo diameter of pial arterioles in response to eNOS-dependent agonists (acetylcholine and ADP), nNOS-dependent agonists (kainate and NMDA), and NOS-independent agonists (nitroglycerin and diethylaminodiazen (NONOate)) in the absence and presence of tetrahydrobiopterin (BH4). RESULTS Topical application of acetylcholine (1.0 and 10 microM), ADP (10 and 100 microM), kainate (100 and 300 microM), and NMDA (100 and 300 microM) produced dose-related dilatation of pial arterioles. However, the magnitude of vasodilation in response to acetylcholine and ADP was significantly less in alcohol-fed male and female rats, and the magnitude of vasodilation in response to kainate and NMDA was significantly less in alcohol-fed male rats. Nitroglycerin and NONOate produced similar vasodilation in non-alcohol-fed and alcohol-fed male and female rats. Application of BH4 did not alter vasodilation in non-alcohol-fed rats but improved impaired eNOS-dependent vasodilation in alcohol-fed male and female rats. CONCLUSIONS Our findings suggest that long-term alcohol consumption impairs eNOS-dependent but not nNOS-dependent dilatation of cerebral arterioles in female rats and that impaired eNOS-dependent vasodilation may be related to a deficiency or alteration in the utilization of BH4.
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Affiliation(s)
- Hong Sun
- Department of Cellular and Integrative Physiology, 985850 Nebraska Medical Center, University of Nebraska Medical Center, Omaha, NE 68198, USA.
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Shuba LM, Missan S, Zhabyeyev P, Linsdell P, McDonald TF. Selective block of swelling-activated Cl- channels over cAMP-dependent Cl- channels in ventricular myocytes. Eur J Pharmacol 2005; 491:111-20. [PMID: 15140627 DOI: 10.1016/j.ejphar.2004.03.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Accepted: 03/17/2004] [Indexed: 11/21/2022]
Abstract
The objective of this study on guinea-pig and rabbit ventricular myocytes was to evaluate the sensitivities of swelling-activated Cl- current (ICl(swell)) and cAMP-dependent cystic fibrosis transmembrane regulator (CFTR) Cl- current (ICl(CFTR)) to block by dideoxyforskolin and verapamil. The currents were recorded from whole-cell configured myocytes that were dialysed with a Cs+-rich pipette solution and superfused with either isosmotic Na+-, K+-, Ca2+-free solution that contained 140 mM sucrose or hyposmotic sucrose-free solution. Forskolin-activated ICl(CFTR) was inhibited by reference blocker anthracene-9-carboxylic acid but unaffected by < or = 200 microM dideoxyforskolin and verapamil. However, dideoxyforskolin and verapamil had strong inhibitory effects on outwardly-rectifying, inactivating, distilbene-sensitive ICl(swell); IC50 values were approximately 30 microM, and blocks were voltage-independent and reversible. The results establish that dideoxyforskolin and verapamil can be used to distinguish between ICl(CFTR) and ICl(swell) in heart cells, and expand the pharmacological characterization of cardiac ICl(swell).
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Affiliation(s)
- Lesya M Shuba
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7
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Culliford SJ, Borg JJ, O'Brien MJ, Kozlowski RZ. Differential effects of pyrethroids on volume-sensitive anion and organic osmolyte pathways. Clin Exp Pharmacol Physiol 2004; 31:134-44. [PMID: 15008955 DOI: 10.1111/j.1440-1681.2004.03965.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. There are no effective ways of screening for potential modulators of volume-regulated anion channels in their native cell type. Generally, cell lines are used for this purpose. Using HeLa and C6 glioma cells, we identified the pyrethroids as a novel class of compounds that inhibit taurine efflux through volume-regulated anion transport pathways in these cells. Subsequently, we examined their effects on volume-regulated anion channels in guinea-pig ventricular myocytes to determine whether results obtained using cell lines could be extrapolated to other tissues. 2. Tetramethrin inhibited taurine efflux in both HeLa and C6 glioma cells with Ki values of approximately 26 and 16 micro mol/L, respectively. Bioallethrin and fenpropathrin inhibited volume-sensitive taurine efflux from C6 glioma cells, but not from HeLa cells. The Ki values for bioallethrin and fenpropathrin were 70 and 59 micro mol/L, respectively. 3. Volume-sensitive I- efflux was observed in HeLa cells but not in C6 glioma cells, suggesting that the taurine efflux pathway in C6 glioma cells may be different to that of the I- efflux pathway. Cyfluthrin, tetramethrin, fenpropathrin, tefluthrin and bioallethrin all significantly inhibited volume-sensitive I- efflux from HeLa cells at 100 micro mol/L. 4. Patch-clamp experiments have shown inhibition of ICl,vol in guinea-pig ventricular myocytes by fenpropathrin, but not tetramethrin or cypermethrin, at 100 micro mol/L. This revealed that further differences exist between ICl,vol in guinea-pig ventricular myocytes and the anion transport pathways in C6 glioma and HeLa cells. 5. In conclusion, we have shown that pyrethroids differentially inhibit volume-regulated anion and taurine efflux in a number of cell types. Because these compounds have different effects in different cells, it is likely that: (i) more than one pathway is involved in the volume-sensitive transport of anions and organic osmolytes; and (ii) the molecular identities of the channels underlying anion transport are different. Finally, for the reasons given above, care should be taken when extrapolating data from one cell type to another. However, in the absence of an existing high-throughput screen, taurine efflux still represents a viable route for the identification of potential modulators of volume-regulated ion channels.
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Affiliation(s)
- Steve J Culliford
- Department of Pharmacology, School of Medical Sciences, University of Bristol, Bristol and Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, UK
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Falktoft B, Lambert IH. Ca2+-mediated Potentiation of the Swelling-induced Taurine Efflux from HeLa Cells: On the Role of Calmodulin and Novel Protein Kinase C Isoforms. J Membr Biol 2004; 201:59-75. [PMID: 15630544 DOI: 10.1007/s00232-004-0705-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Revised: 07/19/2004] [Indexed: 11/27/2022]
Abstract
The present work sets out to investigate how Ca(2+) regulates the volume-sensitive taurine-release pathway in HeLa cells. Addition of Ca(2+)-mobilizing agonists at the time of exposure to hypotonic NaCl medium augments the swelling-induced taurine release and subsequently accelerates the inactivation of the release pathway. The accelerated inactivation is not observed in hypotonic Ca(2+)-free or high-K(+) media. Addition of Ca(2+)-mobilizing agonists also accelerates the regulatory volume decrease, which probably reflects activation of Ca(2+)-activated K(+) channels. The taurine release from control cells and cells exposed to Ca(2+) agonists is equally affected by changes in cell volume, application of DIDS and arachidonic acid, indicating that the volume-sensitive taurine leak pathway mediates the Ca(2+)-augmented taurine release. Exposure to Ca(2+)-mobilizing agonists prior to a hypotonic challenge also augments a subsequent swelling-induced taurine release even though the intracellular Ca(2+)-concentration has returned to the unstimulated level. The Ca(2+)-induced augmentation of the swelling-induced taurine release is abolished by inhibition of calmodulin, but unaffected by inhibition of calmodulin-dependent kinase II, myosin light chain kinase and calcineurin. The effect of Ca(2+)-mobilizing agonists is mimicked by protein kinase C (PKC) activation and abolished in the presence of the PKC inhibitor Gö6850 and following downregulation of phorbol ester-sensitive PKC isoforms. It is suggested that Ca(2+) regulates the volume-sensitive taurine-release pathway through activation of calmodulin and PKC isoforms belonging to the novel subclass (nPKC).
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Affiliation(s)
- B Falktoft
- Biochemical Department, August Krogh Institute, Universitetsparken 13, Copenhagen, DK-2100 Denmark
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Abstract
Change in the intracellular concentration of osmolytes or the extracellular tonicity results in a rapid transmembrane water flow in mammalian cells until intracellular and extracellular tonicities are equilibrated. Most cells respond to the osmotic cell swelling by activation of volume-sensitive flux pathways for ions and organic osmolytes to restore their original cell volume. Taurine is an important organic osmolyte in mammalian cells, and taurine release via a volume-sensitive taurine efflux pathway is increased and the active taurine uptake via the taurine specific taurine transporter TauT decreased following osmotic cell swelling. The cellular signaling cascades, the second messengers profile, the activation of specific transporters, and the subsequent time course for the readjustment of the cellular content of osmolytes and volume vary from cell type to cell type. Using Ehrlich ascites tumor cells, NIH3T3 mouse fibroblasts and HeLa cells as biological systems, it is revealed that phospholipase A2-mediated mobilization of arachidonic acid from phospholipids and subsequent oxidation of the fatty acid via lipoxygenase systems to potent eicosanoids are essential elements in the signaling cascade that is activated by cell swelling and leads to release of osmolytes. The cellular signaling cascade and the activity of the volume-sensitive taurine efflux pathway are modulated by elements of the cytoskeleton, protein tyrosine kinases/phosphatases, GTP-binding proteins, Ca2+/calmodulin, and reactive oxygen species and nucleotides. Serine/threonine phosphorylation of the active taurine uptake system TauT or a putative regulator, as well as change in the membrane potential, are important elements in the regulation of TauT activity. A model describing the cellular sequence, which is activated by cell swelling and leads to activation of the volume-sensitive efflux pathway, is presented at the end of the review.
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Affiliation(s)
- Ian Henry Lambert
- The August Krogh Institute, Biochemical Department, Universitetsparken 13, DK-2100, Copenhagen O, Denmark.
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Gramaglia D, Gentile A, Battaglia M, Ranzato L, Petronilli V, Fassetta M, Bernardi P, Rasola A. Apoptosis to necrosis switching downstream of apoptosome formation requires inhibition of both glycolysis and oxidative phosphorylation in a BCL-X(L)- and PKB/AKT-independent fashion. Cell Death Differ 2004; 11:342-53. [PMID: 14713956 DOI: 10.1038/sj.cdd.4401326] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Human T-lymphoma Jurkat cells treated with several intrinsic death stimuli readily undergo a stepwise apoptotic program. Treatment with 1,9-dideoxyforskolin (ddFSK), an inactive analogue of the adenylate cyclase activator forskolin, induces necrotic cell death and switches to necrosis the response to the apoptosis inducers in Jurkat and in other cell models. Yet, in the presence of ddFSK, mitochondrial changes are enhanced and apoptosome formation takes place. We show that ddFSK does not inhibit the catabolic steps of apoptosis, but rather elicits a profound ATP depletion that in turn tunes the mode of cell demise towards necrosis. Treatment with ddFSK impairs both glycolysis and oxidative phosphorylation in a Bcl-X(L)- and PKB/Akt-independent fashion, and inhibition of both processes is needed to affect apoptosis progression. Apoptosis is not blocked per se by ATP depletion, as engagement of the Fas receptor directly activates caspases, thus bypassing ddFSK inhibition.
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Affiliation(s)
- D Gramaglia
- Division of Molecular Oncology, Institute for Cancer Research, University of Torino Medical School, Candiolo, Italy.
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Chrissobolis S, Budzyn K, Marley PD, Sobey CG. Evidence that estrogen suppresses rho-kinase function in the cerebral circulation in vivo. Stroke 2004; 35:2200-5. [PMID: 15256679 DOI: 10.1161/01.str.0000136951.85586.c8] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND AND PURPOSE Premenopausal women are less susceptible to cardiovascular diseases than men or postmenopausal women. Such disease states are often associated with increased vascular RhoA/Rho-kinase activity and decreased activity of nitric oxide (NO). This study tested whether female gender is associated with lower Rho-kinase activity or higher NO activity in cerebral arteries in vivo and whether estrogen contributes to any such gender differences. METHODS Changes in basilar artery diameter were measured with the use of a cranial window preparation in anesthetized Sprague-Dawley rats. Some female rats were ovariectomized (OVX) and treated subcutaneously daily for 14 days with vehicle (dimethyl sulfoxide) or 17beta-estradiol. Vascular expression of RhoA or Rho-kinase was assessed by Western blotting. RESULTS The Rho-kinase inhibitor Y-27632 was selectively approximately 3-fold more potent as a cerebral vasodilator in males versus females. Expression of total RhoA or Rho-kinase did not differ between males and females. In OVX rats, vasodilator responses to Y-27632 resembled responses in males. Treatment of OVX rats with 17beta-estradiol normalized the vasodilator effects of Y-27632 to be equivalent to responses in intact female controls. The NO synthase inhibitor N-nitro-l-arginine methyl ester caused approximately 50% greater constriction of the basilar artery in females versus males, but responses in OVX rats treated with either vehicle or 17beta-estradiol did not differ from those recorded in intact females. CONCLUSIONS These data indicate that vascular Rho-kinase function is suppressed in females because of the effects of estrogen, whereas the higher NO activity in females is estrogen independent.
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Lambert IH. Regulation of the volume-sensitive taurine efflux pathway in NIH3T3 mouse fibroblasts. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 526:115-22. [PMID: 12908591 DOI: 10.1007/978-1-4615-0077-3_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Affiliation(s)
- Ian Henry Lambert
- The August Krogh Institute, Universitetsparken 13, DK-2100, Copenhagen O, Denmark.
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Lambert IH. Modulation of volume-sensitive taurine release from NIH3T3 mouse fibroblasts by reactive oxygen species. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 559:369-378. [PMID: 18727256 DOI: 10.1007/0-387-23752-6_34] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Ian Henry Lambert
- The August Krogh Institute, Biochemical Department, Universitetsparken 13, DK-2300 Copenhagen O, Denmark.
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Smolders RGV, van der Mooren MJ, Sipkema P, Kenemans P. Estrogens, homocysteine, vasodilatation and menopause: basic mechanisms, interactions and clinical implications. Gynecol Endocrinol 2003; 17:339-54. [PMID: 14503980 DOI: 10.1080/gye.17.4.339.354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Estrogens influence the independent cardiovascular risk factor homocysteine as well as vasodilatation. Homocysteine alone also influences vasodilatation, indicating a relational triangle that seems important in interpreting the isolated effects of estrogens on homocysteine metabolism and vasoreactivity. This paper gives an overview of the current understanding regarding vasoreactivity, homocysteine metabolism and the role of estrogens. This is placed against the background of the clinical trials on the effect of postmenopausal hormone replacement therapy on homocysteine levels and addresses the importance of the interaction between homocysteine, estrogens and vasoreactivity.
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Affiliation(s)
- R G V Smolders
- Project Aging Women, Institute for Cardiovascular Research, Vrije Universiteit, VU University Medical Center, 1007 MB Amsterdam, The Netherlands
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Davis RJ, Doerflinger A, McCurley M, Swithers SE. Gastric emptying and control of ingestion in preweanling rat pups. Nutr Neurosci 2003; 6:81-91. [PMID: 12722983 DOI: 10.1080/1028415031000084463] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
In adult rats, the rate of gastric emptying is modulated by properties of the diet, including its caloric content and osmotic properties. In developing pups, there is little known about the modulation of gastric emptying, despite evidence that volume of gastric contents may play a significant role in modulating intake in young rats. The present experiments examined gastric emptying of oral infusions of corn oil emulsions or glucose solutions in pups aged 6 or 15 days of age and their effects on independent ingestion. The results demonstrated that pups as young as 6 days of age modulate the rate of gastric emptying in response to changes in the concentration of a corn oil or glucose diet. However, oral infusions of corn oil emulsions failed to produce differences in subsequent intake of a milk diet, while oral infusions of a glucose diet did suppress subsequent intake. Taken together, the results support different ontogenetic courses for the development of mechanisms modulating gastric emptying of lipid versus carbohydrate diets, and suggest that gastric fill plays a limited role in modulation of intake in young pups.
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Affiliation(s)
- Richard J Davis
- Department of Psychological Sciences, Purdue University, West Lafayette, IN 47907-1364, USA
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