1
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Zsombok A, Desmoulins LD, Derbenev AV. Sympathetic circuits regulating hepatic glucose metabolism: where we stand. Physiol Rev 2024; 104:85-101. [PMID: 37440208 DOI: 10.1152/physrev.00005.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 06/12/2023] [Accepted: 07/10/2023] [Indexed: 07/14/2023] Open
Abstract
The prevalence of metabolic disorders, including type 2 diabetes mellitus, continues to increase worldwide. Although newer and more advanced therapies are available, current treatments are still inadequate and the search for solutions remains. The regulation of energy homeostasis, including glucose metabolism, involves an exchange of information between the nervous systems and peripheral organs and tissues; therefore, developing treatments to alter central and/or peripheral neural pathways could be an alternative solution to modulate whole body metabolism. Liver glucose production and storage are major mechanisms controlling glycemia, and the autonomic nervous system plays an important role in the regulation of hepatic functions. Autonomic nervous system imbalance contributes to excessive hepatic glucose production and thus to the development and progression of type 2 diabetes mellitus. At cellular levels, change in neuronal activity is one of the underlying mechanisms of autonomic imbalance; therefore, modulation of the excitability of neurons involved in autonomic outflow governance has the potential to improve glycemic status. Tissue-specific subsets of preautonomic neurons differentially control autonomic outflow; therefore, detailed information about neural circuits and properties of liver-related neurons is necessary for the development of strategies to regulate liver functions via the autonomic nerves. This review provides an overview of our current understanding of the hypothalamus-ventral brainstem-liver pathway involved in the sympathetic regulation of the liver, outlines strategies to identify organ-related neurons, and summarizes neuronal plasticity during diabetic conditions with a particular focus on liver-related neurons in the paraventricular nucleus.
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Affiliation(s)
- Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana, United States
- Tulane Brain Institute, Tulane University, New Orleans, Louisiana, United States
| | - Lucie D Desmoulins
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana, United States
| | - Andrei V Derbenev
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana, United States
- Tulane Brain Institute, Tulane University, New Orleans, Louisiana, United States
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2
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Daniel JM, Lindsey SH, Mostany R, Schrader LA, Zsombok A. Cardiometabolic health, menopausal estrogen therapy and the brain: How effects of estrogens diverge in healthy and unhealthy preclinical models of aging. Front Neuroendocrinol 2023; 70:101068. [PMID: 37061205 PMCID: PMC10725785 DOI: 10.1016/j.yfrne.2023.101068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/23/2023] [Accepted: 04/10/2023] [Indexed: 04/17/2023]
Abstract
Research in preclinical models indicates that estrogens are neuroprotective and positively impact cognitive aging. However, clinical data are equivocal as to the benefits of menopausal estrogen therapy to the brain and cognition. Pre-existing cardiometabolic disease may modulate mechanisms by which estrogens act, potentially reducing or reversing protections they provide against cognitive decline. In the current review we propose mechanisms by which cardiometabolic disease may alter estrogen effects, including both alterations in actions directly on brain memory systems and actions on cardiometabolic systems, which in turn impact brain memory systems. Consideration of mechanisms by which estrogen administration can exert differential effects dependent upon health phenotype is consistent with the move towards precision or personalized medicine, which aims to determine which treatment interventions will work for which individuals. Understanding effects of estrogens in both healthy and unhealthy models of aging is critical to optimizing the translational link between preclinical and clinical research.
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Affiliation(s)
- Jill M Daniel
- Department of Psychology and Brain Institute, Tulane University, New Orleans, LA, United States.
| | - Sarah H Lindsey
- Department of Pharmacology and Brain Institute, Tulane University, New Orleans, LA, United States
| | - Ricardo Mostany
- Department of Pharmacology and Brain Institute, Tulane University, New Orleans, LA, United States
| | - Laura A Schrader
- Department of Cell & Molecular Biology and Brain Institute, Tulane University, New Orleans, LA, United States
| | - Andrea Zsombok
- Department of Physiology and Brain Institute, Tulane University, New Orleans, LA, United States
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3
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Molinas AJR, Desmoulins LD, Davis RK, Gao H, Satou R, Derbenev AV, Zsombok A. High-Fat Diet Modulates the Excitability of Neurons within the Brain-Liver Pathway. Cells 2023; 12:1194. [PMID: 37190103 PMCID: PMC10137256 DOI: 10.3390/cells12081194] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 04/14/2023] [Accepted: 04/16/2023] [Indexed: 05/17/2023] Open
Abstract
Stimulation of hepatic sympathetic nerves increases glucose production and glycogenolysis. Activity of pre-sympathetic neurons in the paraventricular nucleus (PVN) of the hypothalamus and in the ventrolateral and ventromedial medulla (VLM/VMM) largely influence the sympathetic output. Increased activity of the sympathetic nervous system (SNS) plays a role in the development and progression of metabolic diseases; however, despite the importance of the central circuits, the excitability of pre-sympathetic liver-related neurons remains to be determined. Here, we tested the hypothesis that the activity of liver-related neurons in the PVN and VLM/VMM is altered in diet-induced obese mice, as well as their response to insulin. Patch-clamp recordings were conducted from liver-related PVN neurons, VLM-projecting PVN neurons, and pre-sympathetic liver-related neurons in the ventral brainstem. Our data demonstrate that the excitability of liver-related PVN neurons increased in high-fat diet (HFD)-fed mice compared to mice fed with control diet. Insulin receptor expression was detected in a population of liver-related neurons, and insulin suppressed the firing activity of liver-related PVN and pre-sympathetic VLM/VMM neurons in HFD mice; however, it did not affect VLM-projecting liver-related PVN neurons. These findings further suggest that HFD alters the excitability of pre-autonomic neurons as well as their response to insulin.
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Affiliation(s)
- Adrien J. R. Molinas
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA 70130, USA; (A.J.R.M.); (L.D.D.); (R.K.D.); (R.S.); (A.V.D.)
| | - Lucie D. Desmoulins
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA 70130, USA; (A.J.R.M.); (L.D.D.); (R.K.D.); (R.S.); (A.V.D.)
| | - Roslyn K. Davis
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA 70130, USA; (A.J.R.M.); (L.D.D.); (R.K.D.); (R.S.); (A.V.D.)
| | - Hong Gao
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA 70130, USA; (A.J.R.M.); (L.D.D.); (R.K.D.); (R.S.); (A.V.D.)
| | - Ryousuke Satou
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA 70130, USA; (A.J.R.M.); (L.D.D.); (R.K.D.); (R.S.); (A.V.D.)
| | - Andrei V. Derbenev
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA 70130, USA; (A.J.R.M.); (L.D.D.); (R.K.D.); (R.S.); (A.V.D.)
- Tulane Brain Institute, Tulane University, New Orleans, LA 70130, USA
| | - Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA 70130, USA; (A.J.R.M.); (L.D.D.); (R.K.D.); (R.S.); (A.V.D.)
- Tulane Brain Institute, Tulane University, New Orleans, LA 70130, USA
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4
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Jiang Y, Rezai-Zadeh K, Desmoulins LD, Muenzberg H, Derbenev AV, Zsombok A. GABAergic leptin receptor-expressing neurons in the dorsomedial hypothalamus project to brown adipose tissue-related neurons in the paraventricular nucleus of mice. Auton Neurosci 2023; 245:103058. [PMID: 36538864 PMCID: PMC9899324 DOI: 10.1016/j.autneu.2022.103058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 11/14/2022] [Accepted: 12/08/2022] [Indexed: 12/15/2022]
Abstract
Brown adipose tissue (BAT) contributes to energy homeostasis via nonshivering thermogenesis. The BAT is densely innervated by the sympathetic nervous system (SNS) and activity of pre-autonomic neurons modulates the sympathetic outflow. Leptin, an adipocyte hormone, alters energy homeostasis and thermogenesis of BAT via several neuronal circuits; however, the cellular effects of leptin on interscapular BAT (iBAT)-related neurons in the hypothalamus remain to be determined. In this study, we used pseudorabies virus (PRV) to identify iBAT-related neurons in the paraventricular nucleus (PVN) of the hypothalamus and test the hypothesis that iBAT-related PVN neurons are modulated by leptin. Inoculation of iBAT with PRV in leptin receptor reporter mice (Lepr:EGFP) demonstrated that a population of iBAT-related PVN neurons expresses Lepr receptors. Our electrophysiological findings revealed that leptin application caused hyperpolarization in some of iBAT-related PVN neurons. Bath application of leptin also modulated excitatory and inhibitory neurotransmission to most of iBAT-related PVN neurons. Using channel rhodopsin assisted circuit mapping we found that GABAergic and glutamatergic Lepr-expressing neurons in the dorsomedial hypothalamus/dorsal hypothalamic area (dDMH/DHA) project to PVN neurons; however, connected iBAT-related PVN neurons receive exclusively inhibitory signals from Lepr-expressing dDMH/DHA neurons.
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Affiliation(s)
- Yanyan Jiang
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA, United States of America; Neuroscience Program, Tulane Brain Institute, Tulane University, New Orleans, LA, United States of America
| | - Kavon Rezai-Zadeh
- Central Leptin Signaling, Pennington Biomedical Research Center, LSU System, Baton Rouge, LA, United States of America
| | - Lucie D Desmoulins
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA, United States of America
| | - Heike Muenzberg
- Central Leptin Signaling, Pennington Biomedical Research Center, LSU System, Baton Rouge, LA, United States of America
| | - Andrei V Derbenev
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA, United States of America; Neuroscience Program, Tulane Brain Institute, Tulane University, New Orleans, LA, United States of America
| | - Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA, United States of America; Neuroscience Program, Tulane Brain Institute, Tulane University, New Orleans, LA, United States of America.
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5
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Beneficial effects of metformin supplementation in hypothalamic paraventricular nucleus and arcuate nucleus of type 2 diabetic rats. Toxicol Appl Pharmacol 2022; 437:115893. [DOI: 10.1016/j.taap.2022.115893] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 01/11/2022] [Accepted: 01/19/2022] [Indexed: 12/13/2022]
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6
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Torres H, Huesing C, Burk DH, Molinas AJR, Neuhuber WL, Berthoud HR, Münzberg H, Derbenev AV, Zsombok A. Sympathetic innervation of the mouse kidney and liver arising from prevertebral ganglia. Am J Physiol Regul Integr Comp Physiol 2021; 321:R328-R337. [PMID: 34231420 DOI: 10.1152/ajpregu.00079.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sympathetic nervous system (SNS) plays a crucial role in the regulation of renal and hepatic functions. Although sympathetic nerves to the kidney and liver have been identified in many species, specific details are lacking in the mouse. In the absence of detailed information of sympathetic prevertebral innervation of specific organs, selective manipulation of a specific function will remain challenging. Despite providing major postganglionic inputs to abdominal organs, limited data are available about the mouse celiac-superior mesenteric complex. We used tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DbH) reporter mice to visualize abdominal prevertebral ganglia. We found that both the TH and DbH reporter mice are useful models for identification of ganglia and nerve bundles. We further tested if the celiac-superior mesenteric complex provides differential inputs to the mouse kidney and liver. The retrograde viral tracer, pseudorabies virus (PRV)-152 was injected into the cortex of the left kidney or the main lobe of the liver to identify kidney-projecting and liver-projecting neurons in the celiac-superior mesenteric complex. iDISCO immunostaining and tissue clearing were used to visualize unprecedented anatomical detail of kidney-related and liver-related postganglionic neurons in the celiac-superior mesenteric complex and aorticorenal and suprarenal ganglia compared with TH-positive neurons. Kidney-projecting neurons were restricted to the suprarenal and aorticorenal ganglia, whereas only sparse labeling was observed in the celiac-superior mesenteric complex. In contrast, liver-projecting postganglionic neurons were observed in the celiac-superior mesenteric complex and aorticorenal and suprarenal ganglia, suggesting spatial separation between the sympathetic innervation of the mouse kidney and liver.
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Affiliation(s)
- Hayden Torres
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Clara Huesing
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - David H Burk
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Adrien J R Molinas
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana
| | | | - Hans-Rudolf Berthoud
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Heike Münzberg
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | - Andrei V Derbenev
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana.,Brain Institute, Tulane University, New Orleans, Louisiana
| | - Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana.,Brain Institute, Tulane University, New Orleans, Louisiana
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7
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Abstract
Transient receptor potential vanilloid subfamily member 1 (TRPV1) is a nonselective cation channel, that is mainly distributed in sensory nerve endings and can release a variety of neurotransmitters after activation. Early studies showed that it mainly conducts pain sensation, but research has demonstrated that it also plays an important role in cardiovascular diseases. Notably, in atherosclerosis, the activation of TRPV1 can regulate lipid metabolism, reduce foam cell formation, protect endothelial cells, inhibit smooth muscle cell proliferation and inhibit inflammation and oxidation. In this review, the role of the TRPV1 channel in atherosclerosis was discussed to provide new ideas for the prevention and treatment of atherosclerotic diseases.
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Affiliation(s)
- Chenyang Zhang
- Department of Medicine, Qingdao University, Qingdao, China.,Zhejiang Provincial People's Hospital, Qingdao University, Hangzhou, China
| | - Lifang Ye
- Zhejiang Provincial People's Hospital, Qingdao University, Hangzhou, China
| | - Qinggang Zhang
- Zhejiang Provincial People's Hospital, Qingdao University, Hangzhou, China
| | - Fei Wu
- Zhejiang Provincial People's Hospital, Qingdao University, Hangzhou, China
| | - Lihong Wang
- Zhejiang Provincial People's Hospital, Qingdao University, Hangzhou, China
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8
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Bruce KD, Dobrinskikh E, Wang H, Rudenko I, Gao H, Libby AE, Gorkhali S, Yu T, Zsombok A, Eckel RH. Neuronal Lipoprotein Lipase Deficiency Alters Neuronal Function and Hepatic Metabolism. Metabolites 2020; 10:metabo10100385. [PMID: 32998280 PMCID: PMC7600143 DOI: 10.3390/metabo10100385] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/31/2020] [Accepted: 09/21/2020] [Indexed: 12/31/2022] Open
Abstract
The autonomic regulation of hepatic metabolism offers a novel target for the treatment of non-alcoholic fatty liver disease (NAFLD). However, the molecular characteristics of neurons that regulate the brain-liver axis remain unclear. Since mice lacking neuronal lipoprotein lipase (LPL) develop perturbations in neuronal lipid-sensing and systemic energy balance, we reasoned that LPL might be a component of pre-autonomic neurons involved in the regulation of hepatic metabolism. Here, we show that, despite obesity, mice with reduced neuronal LPL (NEXCreLPLflox (LPL KD)) show improved glucose tolerance and reduced hepatic lipid accumulation with aging compared to wilt type (WT) controls (LPLflox). To determine the effect of LPL deficiency on neuronal physiology, liver-related neurons were identified in the paraventricular nucleus (PVN) of the hypothalamus using the transsynaptic retrograde tracer PRV-152. Patch-clamp studies revealed reduced inhibitory post-synaptic currents in liver-related neurons of LPL KD mice. Fluorescence lifetime imaging microscopy (FLIM) was used to visualize metabolic changes in LPL-depleted neurons. Quantification of free vs. bound nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) revealed increased glucose utilization and TCA cycle flux in LPL-depleted neurons compared to controls. Global metabolomics from hypothalamic cell lines either deficient in or over-expressing LPL recapitulated these findings. Our data suggest that LPL is a novel feature of liver-related preautonomic neurons in the PVN. Moreover, LPL loss is sufficient to cause changes in neuronal substrate utilization and function, which may precede changes in hepatic metabolism.
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Affiliation(s)
- Kimberley D. Bruce
- Division of Endocrinology, Metabolism, & Diabetes, Denver Anschutz Medical Campus, University of Colorado, Aurora, CO 80045, USA; (H.W.); (I.R.); (S.G.); (T.Y.); (R.H.E.)
- Correspondence:
| | - Evgenia Dobrinskikh
- Department of Medicine, University of Colorado, Denver Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - Hong Wang
- Division of Endocrinology, Metabolism, & Diabetes, Denver Anschutz Medical Campus, University of Colorado, Aurora, CO 80045, USA; (H.W.); (I.R.); (S.G.); (T.Y.); (R.H.E.)
| | - Ivan Rudenko
- Division of Endocrinology, Metabolism, & Diabetes, Denver Anschutz Medical Campus, University of Colorado, Aurora, CO 80045, USA; (H.W.); (I.R.); (S.G.); (T.Y.); (R.H.E.)
| | - Hong Gao
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA 70112, USA; (H.G.); (A.Z.)
| | - Andrew E. Libby
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC 20057, USA;
| | - Sachi Gorkhali
- Division of Endocrinology, Metabolism, & Diabetes, Denver Anschutz Medical Campus, University of Colorado, Aurora, CO 80045, USA; (H.W.); (I.R.); (S.G.); (T.Y.); (R.H.E.)
| | - Tian Yu
- Division of Endocrinology, Metabolism, & Diabetes, Denver Anschutz Medical Campus, University of Colorado, Aurora, CO 80045, USA; (H.W.); (I.R.); (S.G.); (T.Y.); (R.H.E.)
| | - Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA 70112, USA; (H.G.); (A.Z.)
| | - Robert H. Eckel
- Division of Endocrinology, Metabolism, & Diabetes, Denver Anschutz Medical Campus, University of Colorado, Aurora, CO 80045, USA; (H.W.); (I.R.); (S.G.); (T.Y.); (R.H.E.)
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9
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Liu J, Du J, Wang Y. CDK5 inhibits the clathrin-dependent internalization of TRPV1 by phosphorylating the clathrin adaptor protein AP2μ2. Sci Signal 2019; 12:12/585/eaaw2040. [PMID: 31186372 DOI: 10.1126/scisignal.aaw2040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Transient receptor potential vanilloid 1 (TRPV1), a nonselective, ligand-gated cation channel, responds to multiple noxious stimuli and is targeted by many kinases that influence its trafficking and activity. Studies on the internalization of TRPV1 have mainly focused on that induced by capsaicin or other agonists. Here, we report that constitutive internalization of TRPV1 occurred in a manner dependent on clathrin, dynamin, and adaptor protein complex 2 (AP2). The μ2 subunit of AP2 (AP2μ2) interacted directly with TRPV1 and was required for its constitutive internalization. Cyclin-dependent kinase 5 (CDK5) phosphorylated AP2μ2 at Ser45, which reduced the interaction between TRPV1 and AP2μ2, leading to decreased TRPV1 internalization. Intrathecal delivery of a cell-penetrating fusion peptide corresponding to the Cdk5 phosphorylation site in AP2μ2, which competed with AP2μ2 for phosphorylation by Cdk5, increased the abundance of TRPV1 on the surface of dorsal root ganglion neurons and reduced complete Freund's adjuvant (CFA)-induced inflammatory thermal hyperalgesia in rats. In addition to describing a mechanism of TRPV1 constitutive internalization and its inhibition by CDK5, these findings demonstrate that CDK5 promotes inflammatory thermal hyperalgesia by reducing TRPV1 internalization, providing previously unidentified insights into the search for drug targets to treat pain.
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Affiliation(s)
- Jiao Liu
- Center of Medical and Health Analysis, Peking University Health Science Center, Beijing 100191, China.,Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, the Key Laboratory for Neuroscience of the Ministry of Education/National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China
| | - Junxia Du
- College of Biological Science and Engineering, Xingtai University, Xingtai 054001, Hebei Province, China
| | - Yun Wang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, the Key Laboratory for Neuroscience of the Ministry of Education/National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China. .,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
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10
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Molinas AJR, Desmoulins LD, Hamling BV, Butcher SM, Anwar IJ, Miyata K, Enix CL, Dugas CM, Satou R, Derbenev AV, Zsombok A. Interaction between TRPV1-expressing neurons in the hypothalamus. J Neurophysiol 2019; 121:140-151. [PMID: 30461371 PMCID: PMC6383661 DOI: 10.1152/jn.00004.2018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 10/29/2018] [Accepted: 11/14/2018] [Indexed: 02/08/2023] Open
Abstract
Transient receptor potential vanilloid type 1 (TRPV1) is a ligand-gated ion channel expressed in the peripheral and central nervous systems. TRPV1-dependent mechanisms take part in a wide range of physiological and pathophysiological pathways including the regulation of homeostatic functions. TRPV1 expression in the hypothalamus has been described as well as evidence that TRPV1-dependent excitatory inputs to hypothalamic preautonomic neurons are diminished in diabetic conditions. Here we aimed to determine the functional expression of TRPV1 in two hypothalamic nuclei known to be involved in the central control of metabolism and to test the hypothesis that TRPV1-expressing neurons receive TRPV1-expressing inputs. A mouse model (TRPV1Cre/tdTom) was generated to identify TRPV1-expressing cells and determine the cellular properties of TRPV1-expressing neurons in adult mice. Our study demonstrated the functional expression of TRPV1 in the dorsomedial hypothalamic nucleus and paraventricular nucleus in adult mice. Our findings revealed that a subset of TRPV1Cre/tdTom neurons receive TRPV1-expressing excitatory inputs, indicating direct interaction between TRPV1-expressing neurons. In addition, astrocytes likely play a role in the modulation of TRPV1-expressing neurons. In summary, this study identified specific hypothalamic regions where TRPV1 is expressed and functional in adult mice and the existence of direct connections between TRPV1Cre/tdTom neurons. NEW & NOTEWORTHY Transient receptor potential vanilloid type 1 (TRPV1) is expressed in the hypothalamus, and TRPV1-dependent regulation of preautonomic neurons is decreased in hyperglycemic conditions. Our study demonstrated functional expression of TRPV1 in two hypothalamic nuclei involved in the control of energy homeostasis. Our results also revealed that a subset of TRPV1-expressing neurons receive TRPV1-expressing excitatory inputs. These findings suggest direct interaction between TRPV1-expressing neurons.
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Affiliation(s)
- Adrien J R Molinas
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
| | - Lucie D Desmoulins
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
| | - Brooke V Hamling
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
- Neuroscience Program, Brain Institute, Tulane University , New Orleans, Louisiana
| | - Sierra M Butcher
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
- Neuroscience Program, Brain Institute, Tulane University , New Orleans, Louisiana
| | - Imran J Anwar
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
| | - Kayoko Miyata
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
| | - Courtney L Enix
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
| | - Courtney M Dugas
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
| | - Ryousuke Satou
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
| | - Andrei V Derbenev
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
- Neuroscience Program, Brain Institute, Tulane University , New Orleans, Louisiana
| | - Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University , New Orleans, Louisiana
- Neuroscience Program, Brain Institute, Tulane University , New Orleans, Louisiana
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11
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Bishnoi M, Khare P, Brown L, Panchal SK. Transient receptor potential (TRP) channels: a metabolic TR(i)P to obesity prevention and therapy. Obes Rev 2018; 19:1269-1292. [PMID: 29797770 DOI: 10.1111/obr.12703] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 03/26/2018] [Accepted: 04/11/2018] [Indexed: 12/13/2022]
Abstract
Cellular transport of ions, especially by ion channels, regulates physiological function. The transient receptor potential (TRP) channels, with 30 identified so far, are cation channels with high calcium permeability. These ion channels are present in metabolically active tissues including adipose tissue, liver, gastrointestinal tract, brain (hypothalamus), pancreas and skeletal muscle, which suggests a potential role in metabolic disorders including obesity. TRP channels have potentially important roles in adipogenesis, obesity development and its prevention and therapy because of their physiological properties including calcium permeability, thermosensation and taste perception, involvement in cell metabolic signalling and hormone release. This wide range of actions means that organ-specific actions are unlikely, thus increasing the possibility of adverse effects. Delineation of responses to TRP channels has been limited by the poor selectivity of available agonists and antagonists. Food constituents that can modulate TRP channels are of interest in controlling metabolic status. TRP vanilloid 1 channels modulated by capsaicin have been the most studied, suggesting that this may be the first target for effective pharmacological modulation in obesity. This review shows that most of the TRP channels are potential targets to reduce metabolic disorders through a range of mechanisms.
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Affiliation(s)
- M Bishnoi
- Department of Food and Nutritional Biotechnology, National Agri-Food Biotechnology Institute, S.A.S. Nagar (Mohali), Punjab, India.,Functional Foods Research Group, Institute for Agriculture and the Environment, University of Southern Queensland, Toowoomba, QLD, Australia
| | - P Khare
- Department of Food and Nutritional Biotechnology, National Agri-Food Biotechnology Institute, S.A.S. Nagar (Mohali), Punjab, India
| | - L Brown
- Functional Foods Research Group, Institute for Agriculture and the Environment, University of Southern Queensland, Toowoomba, QLD, Australia.,School of Health and Wellbeing, University of Southern Queensland, Toowoomba, QLD, Australia
| | - S K Panchal
- Functional Foods Research Group, Institute for Agriculture and the Environment, University of Southern Queensland, Toowoomba, QLD, Australia
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12
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Feetham CH, O'Brien F, Barrett-Jolley R. Ion Channels in the Paraventricular Hypothalamic Nucleus (PVN); Emerging Diversity and Functional Roles. Front Physiol 2018; 9:760. [PMID: 30034342 PMCID: PMC6043726 DOI: 10.3389/fphys.2018.00760] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Accepted: 05/30/2018] [Indexed: 12/11/2022] Open
Abstract
The paraventricular nucleus of the hypothalamus (PVN) is critical for the regulation of homeostatic function. Although also important for endocrine regulation, it has been referred to as the "autonomic master controller." The emerging consensus is that the PVN is a multifunctional nucleus, with autonomic roles including (but not limited to) coordination of cardiovascular, thermoregulatory, metabolic, circadian and stress responses. However, the cellular mechanisms underlying these multifunctional roles remain poorly understood. Neurones from the PVN project to and can alter the function of sympathetic control regions in the medulla and spinal cord. Dysfunction of sympathetic pre-autonomic neurones (typically hyperactivity) is linked to several diseases including hypertension and heart failure and targeting this region with specific pharmacological or biological agents is a promising area of medical research. However, to facilitate future medical exploitation of the PVN, more detailed models of its neuronal control are required; populated by a greater compliment of constituent ion channels. Whilst the cytoarchitecture, projections and neurotransmitters present in the PVN are reasonably well documented, there have been fewer studies on the expression and interplay of ion channels. In this review we bring together an up to date analysis of PVN ion channel studies and discuss how these channels may interact to control, in particular, the activity of the sympathetic system.
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Affiliation(s)
- Claire H Feetham
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Fiona O'Brien
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Richard Barrett-Jolley
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
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Overactivity of Liver-Related Neurons in the Paraventricular Nucleus of the Hypothalamus: Electrophysiological Findings in db/db Mice. J Neurosci 2017; 37:11140-11150. [PMID: 29038244 DOI: 10.1523/jneurosci.1706-17.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 09/11/2017] [Accepted: 10/03/2017] [Indexed: 12/11/2022] Open
Abstract
Preautonomic neurons in the paraventricular nucleus (PVN) of the hypothalamus play a large role in the regulation of hepatic functions via the autonomic nervous system. Activation of hepatic sympathetic nerves increases glucose and lipid metabolism and contributes to the elevated hepatic glucose production observed in the type 2 diabetic condition. This augmented sympathetic output could originate from altered activity of liver-related PVN neurons. Remarkably, despite the importance of the brain-liver pathway, the cellular properties of liver-related neurons are not known. In this study, we provide the first evidence of overall activity of liver-related PVN neurons. Liver-related PVN neurons were identified with a retrograde, trans-synaptic, viral tracer in male lean and db/db mice and whole-cell patch-clamp recordings were conducted. In db/db mice, the majority of liver-related PVN neurons fired spontaneously; whereas, in lean mice the majority of liver-related PVN neurons were silent, indicating that liver-related PVN neurons are more active in db/db mice. Persistent, tonic inhibition was identified in liver-related PVN neurons; although, the magnitude of tonic inhibitory control was not different between lean and db/db mice. In addition, our study revealed that the transient receptor potential vanilloid type 1-dependent increase of excitatory neurotransmission was reduced in liver-related PVN neurons of db/db mice. These findings demonstrate plasticity of liver-related PVN neurons and a shift toward excitation in a diabetic mouse model. Our study suggests altered autonomic circuits at the level of the PVN, which can contribute to autonomic dysfunction and dysregulation of neural control of hepatic functions including glucose metabolism.SIGNIFICANCE STATEMENT A growing body of evidence suggests the importance of the autonomic control in the regulation of hepatic metabolism, which plays a major role in the development and progression of type 2 diabetes mellitus. Despite the importance of the brain-liver pathway, the overall activity of liver-related neurons in control and diabetic conditions is not known. This is a significant gap in knowledge, which prevents developing strategies to improve glucose homeostasis via altering the brain-liver pathway. One of the key findings of our study is the overall shift toward excitation in liver-related hypothalamic neurons in the diabetic condition. This overactivity may be one of the underlying mechanisms of elevated sympathetic activity known in metabolically compromised patients and animal models.
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Malenczyk K, Girach F, Szodorai E, Storm P, Segerstolpe Å, Tortoriello G, Schnell R, Mulder J, Romanov RA, Borók E, Piscitelli F, Di Marzo V, Szabó G, Sandberg R, Kubicek S, Lubec G, Hökfelt T, Wagner L, Groop L, Harkany T. A TRPV1-to-secretagogin regulatory axis controls pancreatic β-cell survival by modulating protein turnover. EMBO J 2017; 36:2107-2125. [PMID: 28637794 PMCID: PMC5510001 DOI: 10.15252/embj.201695347] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 04/27/2017] [Accepted: 05/09/2017] [Indexed: 12/20/2022] Open
Abstract
Ca2+-sensor proteins are generally implicated in insulin release through SNARE interactions. Here, secretagogin, whose expression in human pancreatic islets correlates with their insulin content and the incidence of type 2 diabetes, is shown to orchestrate an unexpectedly distinct mechanism. Single-cell RNA-seq reveals retained expression of the TRP family members in β-cells from diabetic donors. Amongst these, pharmacological probing identifies Ca2+-permeable transient receptor potential vanilloid type 1 channels (TRPV1) as potent inducers of secretagogin expression through recruitment of Sp1 transcription factors. Accordingly, agonist stimulation of TRPV1s fails to rescue insulin release from pancreatic islets of glucose intolerant secretagogin knock-out(-/-) mice. However, instead of merely impinging on the SNARE machinery, reduced insulin availability in secretagogin-/- mice is due to β-cell loss, which is underpinned by the collapse of protein folding and deregulation of secretagogin-dependent USP9X deubiquitinase activity. Therefore, and considering the desensitization of TRPV1s in diabetic pancreata, a TRPV1-to-secretagogin regulatory axis seems critical to maintain the structural integrity and signal competence of β-cells.
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Affiliation(s)
- Katarzyna Malenczyk
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Fatima Girach
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Edit Szodorai
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Petter Storm
- Department of Clinical Sciences, Diabetes and Endocrinology CRC, Skåne University Hospital Malmö, Malmö, Sweden
| | - Åsa Segerstolpe
- Integrated Cardio Metabolic Centre, Karolinska Institutet, Huddinge, Sweden
| | | | - Robert Schnell
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Jan Mulder
- Science for Life Laboratory, Karolinska Institutet, Solna, Sweden
| | - Roman A Romanov
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Erzsébet Borók
- Department of Cognitive Neurobiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Fabiana Piscitelli
- Endocannabinoid Research Group, Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Pozzuoli Naples, Italy
| | - Vincenzo Di Marzo
- Endocannabinoid Research Group, Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Pozzuoli Naples, Italy
| | - Gábor Szabó
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Rickard Sandberg
- Integrated Cardio Metabolic Centre, Karolinska Institutet, Huddinge, Sweden
| | - Stefan Kubicek
- CeMM Research Centre for Molecular Medicine, Vienna, Austria
| | - Gert Lubec
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Tomas Hökfelt
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Ludwig Wagner
- University Clinic for Internal Medicine III, General Hospital Vienna, Vienna, Austria
| | - Leif Groop
- Department of Clinical Sciences, Diabetes and Endocrinology CRC, Skåne University Hospital Malmö, Malmö, Sweden
| | - Tibor Harkany
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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15
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Bruce KD, Zsombok A, Eckel RH. Lipid Processing in the Brain: A Key Regulator of Systemic Metabolism. Front Endocrinol (Lausanne) 2017; 8:60. [PMID: 28421037 PMCID: PMC5378716 DOI: 10.3389/fendo.2017.00060] [Citation(s) in RCA: 140] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/17/2017] [Indexed: 12/25/2022] Open
Abstract
Metabolic disorders, particularly aberrations in lipid homeostasis, such as obesity, type 2 diabetes mellitus, and hypertriglyceridemia often manifest together as the metabolic syndrome (MetS). Despite major advances in our understanding of the pathogenesis of these disorders, the prevalence of the MetS continues to rise. It is becoming increasingly apparent that intermediary metabolism within the central nervous system is a major contributor to the regulation of systemic metabolism. In particular, lipid metabolism within the brain is tightly regulated to maintain neuronal structure and function and may signal nutrient status to modulate metabolism in key peripheral tissues such as the liver. There is now a growing body of evidence to suggest that fatty acid (FA) sensing in hypothalamic neurons via accumulation of FAs or FA metabolites may signal nutritional sufficiency and may decrease hepatic glucose production, lipogenesis, and VLDL-TG secretion. In addition, recent studies have highlighted the existence of liver-related neurons that have the potential to direct such signals through parasympathetic and sympathetic nervous system activity. However, to date whether these liver-related neurons are FA sensitive remain to be determined. The findings discussed in this review underscore the importance of the autonomic nervous system in the regulation of systemic metabolism and highlight the need for further research to determine the key features of FA neurons, which may serve as novel therapeutic targets for the treatment of metabolic disorders.
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Affiliation(s)
- Kimberley D. Bruce
- University of Colorado School of Medicine, Division of Endocrinology, Metabolism and Diabetes, Aurora, CO, USA
- *Correspondence: Kimberley D. Bruce,
| | - Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA, USA
| | - Robert H. Eckel
- University of Colorado School of Medicine, Division of Endocrinology, Metabolism and Diabetes, Aurora, CO, USA
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Aghazadeh Tabrizi M, Baraldi PG, Baraldi S, Gessi S, Merighi S, Borea PA. Medicinal Chemistry, Pharmacology, and Clinical Implications of TRPV1 Receptor Antagonists. Med Res Rev 2016; 37:936-983. [PMID: 27976413 DOI: 10.1002/med.21427] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 10/24/2016] [Accepted: 11/01/2016] [Indexed: 12/28/2022]
Abstract
Transient receptor potential vanilloid 1 (TRPV1) is an ion channel expressed on sensory neurons triggering an influx of cations. TRPV1 receptors function as homotetramers responsive to heat, proinflammatory substances, lipoxygenase products, resiniferatoxin, endocannabinoids, protons, and peptide toxins. Its phosphorylation increases sensitivity to both chemical and thermal stimuli, while desensitization involves a calcium-dependent mechanism resulting in receptor dephosphorylation. TRPV1 functions as a sensor of noxious stimuli and may represent a target to avoid pain and injury. TRPV1 activation has been associated to chronic inflammatory pain and peripheral neuropathy. Its expression is also detected in nonneuronal areas such as bladder, lungs, and cochlea where TRPV1 activation is responsible for pathology development of cystitis, asthma, and hearing loss. This review offers a comprehensive overview about TRPV1 receptor in the pathophysiology of chronic pain, epilepsy, cough, bladder disorders, diabetes, obesity, and hearing loss, highlighting how drug development targeting this channel could have a clinical therapeutic potential. Furthermore, it summarizes the advances of medicinal chemistry research leading to the identification of highly selective TRPV1 antagonists and their analysis of structure-activity relationships (SARs) focusing on new strategies to target this channel.
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Affiliation(s)
- Mojgan Aghazadeh Tabrizi
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, 44121, Ferrara, Italy
| | - Pier Giovanni Baraldi
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, 44121, Ferrara, Italy
| | - Stefania Baraldi
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, 44121, Ferrara, Italy
| | - Stefania Gessi
- Section of Pharmacology, Department of Medical Sciences, University of Ferrara, 44121, Ferrara, Italy
| | - Stefania Merighi
- Section of Pharmacology, Department of Medical Sciences, University of Ferrara, 44121, Ferrara, Italy
| | - Pier Andrea Borea
- Section of Pharmacology, Department of Medical Sciences, University of Ferrara, 44121, Ferrara, Italy
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17
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TRP Channels as Therapeutic Targets in Diabetes and Obesity. Pharmaceuticals (Basel) 2016; 9:ph9030050. [PMID: 27548188 PMCID: PMC5039503 DOI: 10.3390/ph9030050] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 08/10/2016] [Accepted: 08/11/2016] [Indexed: 12/16/2022] Open
Abstract
During the last three to four decades the prevalence of obesity and diabetes mellitus has greatly increased worldwide, including in the United States. Both the short- and long-term forecasts predict serious consequences for the near future, and encourage the development of solutions for the prevention and management of obesity and diabetes mellitus. Transient receptor potential (TRP) channels were identified in tissues and organs important for the control of whole body metabolism. A variety of TRP channels has been shown to play a role in the regulation of hormone release, energy expenditure, pancreatic function, and neurotransmitter release in control, obese and/or diabetic conditions. Moreover, dietary supplementation of natural ligands of TRP channels has been shown to have potential beneficial effects in obese and diabetic conditions. These findings raised the interest and likelihood for potential drug development. In this mini-review, we discuss possibilities for better management of obesity and diabetes mellitus based on TRP-dependent mechanisms.
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18
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Boychuk CR, Smith BN. Glutamatergic drive facilitates synaptic inhibition of dorsal vagal motor neurons after experimentally induced diabetes in mice. J Neurophysiol 2016; 116:1498-506. [PMID: 27385796 DOI: 10.1152/jn.00325.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 07/01/2016] [Indexed: 12/31/2022] Open
Abstract
The role of central regulatory circuits in modulating diabetes-associated glucose dysregulation has only recently been under rigorous investigation. One brain region of interest is the dorsal motor nucleus of the vagus (DMV), which contains preganglionic parasympathetic motor neurons that regulate subdiaphragmatic visceral function. Previous research has demonstrated that glutamatergic and GABAergic neurotransmission are independently remodeled after chronic hyperglycemia/hypoinsulinemia. However, glutamatergic circuitry within the dorsal brain stem impinges on GABAergic regulation of the DMV. The present study investigated the role of glutamatergic neurotransmission in synaptic GABAergic control of DMV neurons after streptozotocin (STZ)-induced hyperglycemia/hypoinsulinemia by using electrophysiological recordings in vitro. The frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) was elevated in DMV neurons from STZ-treated mice. The effect was abolished in the presence of the ionotropic glutamate receptor blocker kynurenic acid or the sodium channel blocker tetrodotoxin, suggesting that after STZ-induced hyperglycemia/hypoinsulinemia, increased glutamatergic receptor activity occurs at a soma-dendritic location on local GABA neurons projecting to the DMV. Although sIPSCs in DMV neurons normally demonstrated considerable amplitude variability, this variability was significantly increased after STZ-induced hyperglycemia/hypoinsulinemia. The elevated amplitude variability was not related to changes in quantal release, but rather correlated with significantly elevated frequency of sIPSCs in these mice. Taken together, these findings suggest that GABAergic regulation of central vagal circuitry responsible for the regulation of energy homeostasis undergoes complex functional reorganization after several days of hyperglycemia/hypoinsulinemia, including both glutamate-dependent and -independent forms of plasticity.
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Affiliation(s)
- Carie R Boychuk
- Department of Physiology, University of Kentucky College of Medicine, Lexington, Kentucky
| | - Bret N Smith
- Department of Physiology, University of Kentucky College of Medicine, Lexington, Kentucky
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19
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Derbenev AV, Zsombok A. Potential therapeutic value of TRPV1 and TRPA1 in diabetes mellitus and obesity. Semin Immunopathol 2016; 38:397-406. [PMID: 26403087 PMCID: PMC4808497 DOI: 10.1007/s00281-015-0529-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 09/09/2015] [Indexed: 11/30/2022]
Abstract
Diabetes mellitus and obesity, which is a major risk factor in the development of type 2 diabetes mellitus, have reached epidemic proportions worldwide including the USA. The current statistics and forecasts, both short- and long-term, are alarming and predict severe problems in the near future. Therefore, there is a race for developing new compounds, discovering new receptors, or finding alternative solutions to prevent and/or treat the symptoms and complications related to obesity and diabetes mellitus. It is well demonstrated that members of the transient receptor potential (TRP) superfamily play a crucial role in a variety of biological functions both in health and disease. In the recent years, transient receptor potential vanilloid type 1 (TRPV1) and transient receptor potential ankyrin 1 (TRPA1) were shown to have beneficial effects on whole body metabolism including glucose homeostasis. TRPV1 and TRPA1 have been associated with control of weight, pancreatic function, hormone secretion, thermogenesis, and neuronal function, which suggest a potential therapeutic value of these channels. This review summarizes recent findings regarding TRPV1 and TRPA1 in association with whole body metabolism with emphasis on obese and diabetic conditions.
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Affiliation(s)
- Andrei V Derbenev
- Department of Physiology, School of Medicine, Tulane University, 1430 Tulane Ave., New Orleans, LA, 70112, USA
| | - Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, 1430 Tulane Ave., New Orleans, LA, 70112, USA.
- Department of Medicine, Endocrinology Section, School of Medicine, Tulane University, 1430 Tulane Ave., New Orleans, LA, 70112, USA.
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20
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Thinschmidt JS, Colon-Perez LM, Febo M, Caballero S, King MA, White FA, Grant MB. Depressed basal hypothalamic neuronal activity in type-1 diabetic mice is correlated with proinflammatory secretion of HMBG1. Neurosci Lett 2016; 615:21-7. [PMID: 26777426 PMCID: PMC5399679 DOI: 10.1016/j.neulet.2016.01.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 01/07/2016] [Accepted: 01/11/2016] [Indexed: 02/07/2023]
Abstract
We recently found indicators of hypothalamic inflammation and neurodegeneration linked to the loss of neuroprotective factors including insulin-like growth factor (IGF-1) and IGF binding protein-2 (IGFBP-3) in mice made diabetic using streptozotocin (STZ). In the current work, a genetic model of type-1 diabetes (Ins2(Akita) mouse) was used to evaluate changes in neuronal activity and concomitant changes in the proinflammatory mediator high-mobility group box-1 (HMBG1). We found basal hypothalamic neuronal activity as indicated by manganese-enhanced magnetic resonance imaging (MEMRI) was significantly decreased in 8 months old, but not 2 months old Ins2(Akita) diabetic mice compared to controls. In tissue from the same animals we evaluated the expression of HMBG1 using immunohistochemistry and confocal microscopy. We found decreased HMBG1 nuclear localization in the paraventricular nucleus of the hypothalamus (PVN) in 8 months old, but not 2 months old diabetic animals indicating nuclear release of the protein consistent with an inflammatory state. Adjacent thalamic regions showed little change in HMBG1 nuclear localization and neuronal activity as a result of diabetes. This work extends our previous findings demonstrating changes consistent with hypothalamic neuroinflammation in STZ treated animals, and shows active inflammatory processes are correlated with changes in basal hypothalamic neuronal activity in Ins2(Akita) mice.
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Affiliation(s)
- Jeffrey S Thinschmidt
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | | | - Marcelo Febo
- Department of Psychiatry, University of Florida, Gainesville, FL, USA
| | - Sergio Caballero
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Michael A King
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Fletcher A White
- Department of Anesthesia, Indiana University School of Medicine, IN, USA
| | - Maria B Grant
- Eugene and Marilyn Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, IN, USA.
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21
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RamaKrishnan AM, Sankaranarayanan K. Understanding autoimmunity: The ion channel perspective. Autoimmun Rev 2016; 15:585-620. [PMID: 26854401 DOI: 10.1016/j.autrev.2016.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 01/29/2016] [Indexed: 12/11/2022]
Abstract
Ion channels are integral membrane proteins that orchestrate the passage of ions across the cell membrane and thus regulate various key physiological processes of the living system. The stringently regulated expression and function of these channels hold a pivotal role in the development and execution of various cellular functions. Malfunction of these channels results in debilitating diseases collectively termed channelopathies. In this review, we highlight the role of these proteins in the immune system with special emphasis on the development of autoimmunity. The role of ion channels in various autoimmune diseases is also listed out. This comprehensive review summarizes the ion channels that could be used as molecular targets in the development of new therapeutics against autoimmune disorders.
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Affiliation(s)
| | - Kavitha Sankaranarayanan
- AU-KBC Research Centre, Madras Institute of Technology, Anna University, Chrompet, Chennai 600 044, India.
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22
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O'Hare JD, Zsombok A. Brain-liver connections: role of the preautonomic PVN neurons. Am J Physiol Endocrinol Metab 2016; 310:E183-9. [PMID: 26646097 PMCID: PMC4838125 DOI: 10.1152/ajpendo.00302.2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 12/01/2015] [Indexed: 12/28/2022]
Abstract
Diabetes mellitus and the coexisting conditions and complications, including hypo- and hyperglycemic events, obesity, high cholesterol levels, and many more, are devastating problems. Undoubtedly, there is a huge demand for treatment and prevention of these conditions that justifies the search for new approaches and concepts for better management of whole body metabolism. Emerging evidence demonstrates that the autonomic nervous system is largely involved in the regulation of glucose homeostasis; however, the underlying mechanisms are still under investigation. Within the hypothalamus, the paraventricular nucleus (PVN) is in a unique position to integrate neural and hormonal signals to command both the autonomic and neuroendocrine outflow. This minireview will provide a brief overview on the role of preautonomic PVN neurons and the importance of the PVN-liver pathway in the regulation of glucose homeostasis.
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Affiliation(s)
- James D O'Hare
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana
| | - Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana
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23
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Anwar IJ, Miyata K, Zsombok A. Brain stem as a target site for the metabolic side effects of olanzapine. J Neurophysiol 2015; 115:1389-98. [PMID: 26719086 DOI: 10.1152/jn.00387.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 12/30/2015] [Indexed: 01/27/2023] Open
Abstract
Olanzapine, an atypical antipsychotic, is widely prescribed for the treatment of schizophrenia and bipolar disorder despite causing undesirable metabolic side effects. A variety of mechanisms and brain sites have been proposed as contributors to the side effects; however, the role of the dorsal motor nucleus of the vagus nerve (DMV), which plays a crucial role in the regulation of subdiaphragmatic organs and thus governs energy and glucose homeostasis, is largely unknown. Identifying the effect of olanzapine on the excitability of DMV neurons in both sexes is thus crucial to understanding possible underlying mechanisms. Whole cell patch-clamp electrophysiological recordings were conducted in stomach- and liver-related DMV neurons identified with retrograde viral tracers and in random DMV neurons. The effect of olanzapine on the neuronal excitability of DMV neurons both in male and female mice was established. Our data demonstrate that olanzapine hyperpolarizes the DMV neurons in both sexes and this effect is reversible. The hyperpolarization is associated with decreased firing rate and input resistance. Olanzapine also decreases the excitability of a subset of stomach- and liver-related DMV neurons. Our study demonstrates that olanzapine has a powerful effect on DMV neurons in both sexes, indicating its ability to reduce vagal output to the subdiaphragmatic organs, which likely contributes to the metabolic side effects observed in both humans and experimental models. These findings suggest that the metabolic side effects of olanzapine may partially originate in the DMV.
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Affiliation(s)
- Imran J Anwar
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana
| | - Kayoko Miyata
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana
| | - Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana
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24
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Hulme PA, McBride CL, Kupzyk KA, French JA. Pilot Study on Childhood Sexual Abuse, Diurnal Cortisol Secretion, and Weight Loss in Bariatric Surgery Patients. JOURNAL OF CHILD SEXUAL ABUSE 2015; 24:385-400. [PMID: 26061023 PMCID: PMC5996386 DOI: 10.1080/10538712.2015.1022293] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Childhood sexual abuse increases risk for adult obesity. A potential contributing factor is altered cortisol secretion. In this pilot study, relationships among childhood sexual abuse, diurnal salivary cortisol secretion, and weight loss were explored in 17 bariatric surgery patients. Measurement points were before surgery (baseline) and 3 and 6 months after surgery. Childhood sexual abuse was measured by the Childhood Trauma Questionnaire. The results showed moderate but nonsignificant positive correlations between the childhood sexual abuse subscale score and baseline morning cortisol, evening cortisol, and daily mean cortisol. An unexpected positive correlation was noted between the Childhood Trauma Questionnaire total score and weight loss at six months. Diurnal cortisol secretion did not change over time after surgery nor correlate significantly with weight loss at six months.
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Affiliation(s)
- Polly A Hulme
- a South Dakota State University , Brookings , South Dakota , USA
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25
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Zsombok A, Jiang Y, Gao H, Anwar IJ, Rezai-Zadeh K, Enix CL, Münzberg H, Derbenev AV. Regulation of leptin receptor-expressing neurons in the brainstem by TRPV1. Physiol Rep 2014; 2:2/9/e12160. [PMID: 25263209 PMCID: PMC4270226 DOI: 10.14814/phy2.12160] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The central nervous system plays a critical role in the regulation of feeding behavior and whole‐body metabolism via controlling the autonomic output to the visceral organs. Activity of the parasympathetic neurons in the dorsal motor nucleus of the vagus (DMV) determines the vagal tone and thereby modulates the function of the subdiaphragmatic organs. Leptin is highly involved in the regulation of food intake and alters neuronal excitability of brainstem neurons. Transient receptor potential vanilloid type 1 (TRPV1) has also been shown to increase neurotransmission in the brainstem and we tested the hypothesis that TRPV1 regulates presynaptic neurotransmitter release to leptin receptor‐expressing (LepRbEGFP) DMV neurons. Whole‐cell patch‐clamp recordings were performed to determine the effect of TRPV1 activation on excitatory and inhibitory postsynaptic currents (EPSC, IPSC) of LepRbEGFP neurons in the DMV. Capsaicin, a TRPV1 agonist increased the frequency of miniature EPSCs in 50% of LepRbEGFP neurons without altering the frequency of miniature IPSCs in the DMV. Stomach‐projecting LepRbEGFP neurons were identified in the DMV using the transsynaptic retrograde viral tracer PRV‐614. Activation of TRPV1 increased the frequency of mEPSC in ~50% of stomach‐related LepRbEGFP DMV neurons. These data demonstrate that TRPV1 increases excitatory neurotransmission to a subpopulation of LepRbEGFP DMV neurons via presynaptic mechanisms and suggest a potential interaction between TRPV1 and leptin signaling in the DMV. e12160 Our data demonstrate that TRPV1 is involved in the regulation of a subpopulation of leptin receptor‐expressing neurons in the dorsal motor nucleus of the vagus via presynaptic mechanisms.
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Affiliation(s)
- Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana Neuroscience Program, School of Science and Engineering, Tulane University, New Orleans, Louisiana
| | - Yanyan Jiang
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana Neuroscience Program, School of Science and Engineering, Tulane University, New Orleans, Louisiana
| | - Hong Gao
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana
| | - Imran J Anwar
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana
| | - Kavon Rezai-Zadeh
- Central Leptin Signaling, Pennington Biomedical Research Center, LSU System, Baton Rouge, Louisiana
| | - Courtney L Enix
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana
| | - Heike Münzberg
- Central Leptin Signaling, Pennington Biomedical Research Center, LSU System, Baton Rouge, Louisiana
| | - Andrei V Derbenev
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana Neuroscience Program, School of Science and Engineering, Tulane University, New Orleans, Louisiana
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Rezai-Zadeh K, Yu S, Jiang Y, Laque A, Schwartzenburg C, Morrison CD, Derbenev AV, Zsombok A, Münzberg H. Leptin receptor neurons in the dorsomedial hypothalamus are key regulators of energy expenditure and body weight, but not food intake. Mol Metab 2014; 3:681-93. [PMID: 25352997 PMCID: PMC4209380 DOI: 10.1016/j.molmet.2014.07.008] [Citation(s) in RCA: 140] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 07/22/2014] [Accepted: 07/25/2014] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE Leptin responsive neurons play an important role in energy homeostasis, controlling specific autonomic, behavioral, and neuroendocrine functions. We have previously identified a population of leptin receptor (LepRb) expressing neurons within the dorsomedial hypothalamus/dorsal hypothalamic area (DMH/DHA) which are related to neuronal circuits that control brown adipose tissue (BAT) thermogenesis. Intra-DMH leptin injections also activate sympathetic outflow to BAT, but whether such effects are mediated directly via DMH/DHA LepRb neurons and whether this is physiologically relevant for whole body energy expenditure and body weight regulation has yet to be determined. METHODS We used pharmacosynthetic receptors (DREADDs) to selectively activate DMH/DHA LepRb neurons. We further deleted LepRb with virally driven cre-recombinase from DMH/DHA neurons and determined the physiological importance of DMH/DHA LepRb neurons in whole body energy homeostasis. RESULTS Neuronal activation of DMH/DHA LepRb neurons with DREADDs promoted BAT thermogenesis and locomotor activity, which robustly induced energy expenditure (p < 0.001) and decreases body weight (p < 0.001). Similarly, intra-DMH/DHA leptin injections normalized hypothermia and attenuated body weight gain in leptin-deficient ob/ob mice. Conversely, ablation of LepRb from DMH/DHA neurons remarkably drives weight gain (p < 0.001) by reducing energy expenditure (p < 0.001) and locomotor activity (p < 0.001). The observed changes in body weight were largely independent of food intake. CONCLUSION Taken together, our data highlight that DMH/DHA LepRb neurons are sufficient and necessary to regulate energy expenditure and body weight.
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Affiliation(s)
- Kavon Rezai-Zadeh
- Central Leptin Signaling, Pennington Biomedical Research Center (PBRC), LSU System, Baton Rouge, LA, USA
| | - Sanghou Yu
- Central Leptin Signaling, Pennington Biomedical Research Center (PBRC), LSU System, Baton Rouge, LA, USA
| | - Yanyan Jiang
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA, USA
| | - Amanda Laque
- Central Leptin Signaling, Pennington Biomedical Research Center (PBRC), LSU System, Baton Rouge, LA, USA
| | - Candice Schwartzenburg
- Central Leptin Signaling, Pennington Biomedical Research Center (PBRC), LSU System, Baton Rouge, LA, USA
| | - Christopher D Morrison
- Neurosignaling, Pennington Biomedical Research Center (PBRC), LSU System, Baton Rouge, LA, USA
| | - Andrei V Derbenev
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA, USA
| | - Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA, USA
| | - Heike Münzberg
- Central Leptin Signaling, Pennington Biomedical Research Center (PBRC), LSU System, Baton Rouge, LA, USA
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Abstract
Riera et al. identify a neuroendocrine circuit that controls longevity and the age-dependent onset of metabolic decline via the pain-transducing channel TRPV1. Thus, pharmacological inhibition of TRPV1 may provide a new approach to treat not only metabolic disorders but also a broader range of age-related pathologies.
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Role for the TRPV1 channel in insulin secretion from pancreatic beta cells. J Membr Biol 2014; 247:479-91. [PMID: 24676478 DOI: 10.1007/s00232-014-9658-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 03/10/2014] [Indexed: 02/04/2023]
Abstract
Transient receptor potential channels have been put forward as regulators of insulin secretion. A role for the TRPV1 ion channel in insulin secretion has been suggested in pancreatic beta cell lines. We explored whether TRPV1 is functionally expressed in RINm5F and primary beta cells from neonate and adult rats. We examined if capsaicin could activate cationic non-selective currents. Our results show that TRPV1 channels are not functional in insulin-secreting cells, since capsaicin did not produce current activation, not even under culture conditions known to induce the expression of other ion channels in these cells. Although TRPV1 channels seem to be irrelevant for the physiology of isolated beta cells, they may play a role in glucose homeostasis acting through the nerve fibers that regulate islet function. At the physiological level, we observed that Trpv1 (-/-) mice presented lower fasting insulin levels than their wild-type littermates, however, we did not find differences between these experimental groups nor in the glucose tolerance test or in the insulin secretion. However, we did find that the Trpv1 (-/-) mice exhibited a higher insulin sensitivity compared to their wild-type counterparts. Our results demonstrate that TRPV1 does not contribute to glucose-induced insulin secretion in beta cells as was previously thought, but it is possible that it may control insulin sensitivity.
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Yang HJ, Kwon DY, Kim MJ, Kim DS, Kang S, Shin BK, Lee JJ, Moon NR, Daily JW, Park S. Red peppers with different pungencies and bioactive compounds differentially modulate energy and glucose metabolism in ovariectomized rats fed high fat diets. J Funct Foods 2014. [DOI: 10.1016/j.jff.2014.02.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Jiang Y, Zsombok A. Regulation of neurons in the dorsal motor nucleus of the vagus by SIRT1. Front Neurosci 2014; 7:270. [PMID: 24454277 PMCID: PMC3887315 DOI: 10.3389/fnins.2013.00270] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 12/20/2013] [Indexed: 12/29/2022] Open
Abstract
Neurons in the dorsal motor nucleus of the vagus (DMV) play a critical role in the regulation of autonomic functions. Previous studies indicated that central activation of sirtuin 1 (SIRT1) has beneficial effects on homeostasis, most likely via modulation of the autonomic output. Sirtuins are NAD+-dependent deacetylases and have been associated with longevity. SIRT1 is one of the best-characterized sirtuins expressed in mammals, and may be involved in the regulation of metabolism. Resveratrol, a SIRT1 activator reduced hyperglycemia likely through activation of vagal output; however, the cellular mechanisms of action have not been determined. In this study, whole-cell patch-clamp electrophysiology on acute brainstem slices was used to test the hypothesis that activation of SIRT1 with resveratrol enhances neurotransmission in DMV neurons. Application of resveratrol increased the frequency of spontaneous excitatory postsynaptic currents (sEPSC). This effect was KATP channel-dependent and was prevented with pre-application of SIRT1 inhibitor, EX527. Resveratrol also increased miniature EPSC (mEPSC) frequency without change in amplitude. Furthermore, our data demonstrated that resveratrol regulates excitatory neurotransmission in a PI3 kinase-dependent manner, since wortmannin, a PI3K inhibitor prevented the increase of mEPSC frequency caused by resveratrol. In conclusion, our data demonstrate that resveratrol via SIRT1 increases excitatory neurotransmission to DMV neurons. These observations suggest that activation of SIRT1 may regulate the function of subdiaphragmatic organs through controlling the activity of parasympathetic DMV neurons.
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Affiliation(s)
- Yanyan Jiang
- Neuroscience Program, School of Science and Engineering, Tulane University New Orleans, LA, USA ; Department of Physiology, School of Medicine, Tulane University New Orleans, LA, USA
| | - Andrea Zsombok
- Neuroscience Program, School of Science and Engineering, Tulane University New Orleans, LA, USA ; Department of Physiology, School of Medicine, Tulane University New Orleans, LA, USA
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Anwar IJ, Derbenev AV. TRPV1-dependent regulation of synaptic activity in the mouse dorsal motor nucleus of the vagus nerve. Front Neurosci 2013; 7:238. [PMID: 24379754 PMCID: PMC3862039 DOI: 10.3389/fnins.2013.00238] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 11/26/2013] [Indexed: 11/24/2022] Open
Abstract
The dorsal motor nucleus of the vagus (DMV) is a key integrative point of the parasympathetic neuronal network localized in the dorsal vagal complex. Activity of neurons in the DMV is closely regulated by synaptic inputs, and regulation of excitatory and inhibitory synapsis by transient receptor potential vanilloid type 1 (TRPV1) has been demonstrated. Activation of TRPV1 by heat, protons, endovanilloids, endocannabinoids, and inflammatory mediators is well established. In our study we hypothesized that TRPV1 contributes to the synaptic transmission of DMV neurons at physiological range of temperature without additional stimuli. Using whole-cell patch-clamp recordings we evaluated the effect of a rapid increase of temperature on excitatory and inhibitory neurotransmission and the contribution of TRPV1 to this response. Rapid increase of temperature from 25 to 37°C increased the frequency of miniature excitatory post-synaptic currents (mEPSC) by 351.7%. The frequency of miniature inhibitory post-synaptic currents (mIPSC) also increased by 184.7%. 5′-iodoresiniferatoxin (5′-iRFT), a selective TRPV1 antagonist, prevented the increase of mEPSC and mIPSC frequency. In summary, our data demonstrate that at physiological range of temperature TRPV1 contributes to presynaptic neurotransmission of DMV neurons.
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Affiliation(s)
- Imran J Anwar
- Neuroscience Program, Tulane University, New Orleans LA, USA
| | - Andrei V Derbenev
- Neuroscience Program, Tulane University, New Orleans LA, USA ; Department of Physiology, Health Sciences Center, Tulane University, New Orleans LA, USA
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32
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Gao H, Derbenev AV. Synaptic and extrasynaptic transmission of kidney-related neurons in the rostral ventrolateral medulla. J Neurophysiol 2013; 110:2637-47. [PMID: 24027107 DOI: 10.1152/jn.00155.2013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The rostral ventrolateral medulla (RVLM) is a critical component of the sympathetic nervous system regulating homeostatic functions including arterial blood pressure. Using the transsynaptic retrograde viral tracer PRV-152, we identified kidney-related neurons in the RVLM. We found that PRV-152-labeled RVLM neurons displayed an unusually large persistent, tonic current to both glutamate, via N-methyl-d-aspartate (NMDA) and 2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid (AMPA)/kainate receptors, and to γ-aminobutyric acid (GABA), via GABAA receptors, in the absence of large-scale phasic neurotransmission with whole cell patch-clamp recordings. A cocktail of potent NMDA and AMPA/kainate ionotropic glutamate receptor antagonists AP-5 (50 μM) and CNQX (10 μM) revealed a two-component somatic tonic excitatory current with an overall amplitude of 42.6 ± 13.4 pA. Moreover, application of the GABAA receptor blockers gabazine (15 μM) and bicuculline (30 μM) revealed a robust somatic tonic inhibitory current with an average amplitude of 196.3 ± 39.3 pA. These findings suggest that the tonic current plays a role in determining the resting membrane potential, input resistance, and firing rate of RVLM neurons. The magnitude of the tonic inhibitory current demonstrates that GABAergic inhibition plays a critical role in regulation of kidney-related RVLM neurons. Our results indicate that the GABAergic tonic current may determine the basal tone of firing activity in kidney-related RVLM neurons.
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Affiliation(s)
- Hong Gao
- Department of Physiology, Tulane University Health Sciences Center, New Orleans, Louisiana
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33
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Jiang Y, Gao H, Krantz AM, Derbenev AV, Zsombok A. Reduced GABAergic inhibition of kidney-related PVN neurons in streptozotocin-treated type 1 diabetic mouse. J Neurophysiol 2013; 110:2192-202. [PMID: 23966668 DOI: 10.1152/jn.00013.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Activity of presympathetic neurons in the paraventricular nucleus (PVN) of the hypothalamus is known to play an important role in the regulation of sympathetic outflow. Sympathetic overactivity is associated with many pathophysiological conditions such as diabetes mellitus and hypertension; however, the underlying synaptic mechanisms are poorly understood. In this study, we examined the GABAergic inhibitory synaptic control of kidney-related presympathetic PVN neurons in the streptozotocin-treated type 1 diabetic mouse model, using patch-clamp slice electrophysiology in combination with retrograde labeling. Type 1 diabetes resulted in decreased frequency of miniature inhibitory postsynaptic currents (mIPSCs). Our data also demonstrated a reduction of mIPSC amplitude and mean inhibitory current without alteration of input resistance. Furthermore, our data revealed decreased tonic GABAergic inhibition of kidney-related PVN neurons in diabetic conditions, which was consistent with the observed increased excitability of the presympathetic PVN neurons. In summary, our data demonstrated decreased phasic and tonic inhibitory control of kidney-related presympathetic PVN neurons that suggest altered sympathetic circuitry in type 1 diabetes.
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Affiliation(s)
- Yanyan Jiang
- Neuroscience Program, School of Science and Engineering, Tulane University, New Orleans, Louisiana; and
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34
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McCoy DD, Zhou L, Nguyen AK, Watts AG, Donovan CM, McKemy DD. Enhanced insulin clearance in mice lacking TRPM8 channels. Am J Physiol Endocrinol Metab 2013; 305:E78-88. [PMID: 23651844 PMCID: PMC3725566 DOI: 10.1152/ajpendo.00542.2012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Blood glucose concentration is tightly regulated by the rate of insulin secretion and clearance, a process partially controlled by sensory neurons serving as metabolic sensors in relevant tissues. The activity of these neurons is regulated by the products of metabolism which regulate transmitter release, and recent evidence suggests that neuronally expressed ion channels of the transient receptor potential (TRP) family function in this critical process. Here, we report the novel finding that the cold and menthol-gated channel TRPM8 is necessary for proper insulin homeostasis. Mice lacking TRPM8 respond normally to a glucose challenge while exhibiting prolonged hypoglycemia in response to insulin. Additionally, Trpm8-/- mice have increased rates of insulin clearance compared with wild-type animals and increased expression of insulin-degrading enzyme in the liver. TRPM8 channels are not expressed in the liver, but TRPM8-expressing sensory afferents innervate the hepatic portal vein, suggesting a TRPM8-mediated neuronal control of liver insulin clearance. These results demonstrate that TRPM8 is a novel regulator of serum insulin and support the role of sensory innervation in metabolic homeostasis.
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Affiliation(s)
- Daniel D McCoy
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
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35
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Zsombok A. Vanilloid receptors--do they have a role in whole body metabolism? Evidence from TRPV1. J Diabetes Complications 2013; 27:287-92. [PMID: 23332888 PMCID: PMC3633635 DOI: 10.1016/j.jdiacomp.2012.11.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 11/19/2012] [Accepted: 11/20/2012] [Indexed: 12/16/2022]
Abstract
With increasing lifespan, therapeutic interventions for the treatment of disorders such as type 2 diabetes mellitus are in great demand. Despite billions of dollars invested to reduce the symptoms and complications due to diabetes mellitus, current treatments (e.g., insulin replacements, sensitization) remain inadequate, justifying the search for novel therapeutic approaches or alternative solutions, including dietary supplementation, for the treatment of diabetes mellitus in every age group. The involvement of the vanilloid system in the regulation of metabolism has been identified, and the emerging role of its receptors, the transient receptor potential vanilloid type 1 (TRPV1), in diabetes was recently demonstrated. Indeed, beneficial effects of dietary capsaicin, an agonist of TRPV1 receptors, were identified for improving glucose, insulin and glucagon-like peptide-1 levels. Recent findings regarding TRPV1 receptors in association with whole body metabolism including glucose homeostasis will be reviewed in this article.
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Affiliation(s)
- Andrea Zsombok
- Department of Physiology, Endocrinology Section, Tulane University, School of Medicine, 1430 Tulane Ave., SL39, New Orleans, LA 70112, USA.
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36
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Zsombok A. Autonomic control and bariatric procedures. Auton Neurosci 2013; 177:81-6. [PMID: 23538033 DOI: 10.1016/j.autneu.2013.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 10/10/2012] [Accepted: 03/01/2013] [Indexed: 12/12/2022]
Abstract
The sudden improvement of metabolic profile and the remission of type 2 diabetes after bariatric surgery, well before weight loss, raise important new questions regarding glycemic control. Currently, various types of bariatric procedures target type 2 diabetes in obese and non-obese patients. Nevertheless, the origin of the dramatic metabolic improvements, including glucose homeostasis, is poorly understood, and the role of the gastrointestinal (GI) tract remains relatively speculative, as well as why these procedures are variably effective. One neglected explanation is that such interventions disrupt neural networks mediating GI-brain communication and could alter the autonomic output to the visceral organs, including the liver. Incretins, e.g., glucagon-like peptide 1 (GLP-1), have major influence on the central nervous system. Moreover, the level of GLP-1 is observed to significantly increase after bariatric surgery and could be a key factor in the weight-independent, anti-diabetic effect. Therefore, this review will evaluate the effect of GLP-1 on the central nervous system, with emphasis on the cellular effects of GLP-1, and will provide an overview of the autonomic control of the liver.
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Affiliation(s)
- Andrea Zsombok
- Department of Physiology, Endocrinology Section, Tulane University, School of Medicine, 1430 Tulane Ave., SL39, New Orleans, LA 70112, United States; Department of Medicine, Endocrinology Section, Tulane University, School of Medicine, 1430 Tulane Ave., SL39, New Orleans, LA 70112, United States.
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Kaßmann M, Harteneck C, Zhu Z, Nürnberg B, Tepel M, Gollasch M. Transient receptor potential vanilloid 1 (TRPV1), TRPV4, and the kidney. Acta Physiol (Oxf) 2013; 207:546-64. [PMID: 23253200 DOI: 10.1111/apha.12051] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 11/15/2012] [Accepted: 12/11/2012] [Indexed: 12/13/2022]
Abstract
Recent preclinical data indicate that activators of transient receptor potential channels of the vanilloid receptor subtype 1 (TRPV1) may improve the outcome of ischaemic acute kidney injury (AKI). The underlying mechanisms are unclear, but may involve TRPV1 channels in dorsal root ganglion neurones that innervate the kidney. Recent data identified TRPV4, together with TRPV1, to serve as major calcium influx channels in endothelial cells. In these cells, gating of individual TRPV4 channels within a four-channel cluster provides elementary calcium influx (calcium sparklets) to open calcium-activated potassium channels and promote vasodilation. The TRPV receptors can also form heteromers that exhibit unique conductance and gating properties, further increasing their spatio-functional diversity. This review summarizes data on electrophysiological properties of TRPV1/4 and their modulation by endogenous channel agonists such as 20-HETE, phospholipase C and phosphatidylinositide 3-kinase (PI3 kinase). We review important roles of TRPV1 and TRPV4 in kidney physiology and renal ischaemia reperfusion injury; further studies are warranted to address renoprotective mechanism of vanilloid receptors in ischaemic AKI including the role of the capsaicin receptor TRPV1 in primary sensory nerves and/or endothelium. Particular attention should be paid to understand the kidneys' ability to respond to ischaemic stimuli after catheter-based renal denervation therapy in man, whereas the discovery of novel pharmacological TRPV modulators may be a successful strategy for better treatment of acute or chronic kidney failure.
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Affiliation(s)
- M. Kaßmann
- Charité University Medicine, Section Nephrology/Intensive Care, Campus Virchow, and Experimental and Clinical Research Center (ECRC); Berlin; Germany
| | - C. Harteneck
- Institut für Experimentelle & Klinische Pharmakologie & Toxikologie and Interfaculty Center of Pharmacogenomics and Pharmaceutical Research (ICePhA); Eberhard-Karls-Universität; Tübingen; Germany
| | - Z. Zhu
- Department of Hypertension and Endocrinology, Center for Hypertension and Metabolic Diseases; Daping Hospital, Third Military Medical University, Chongqing Institute of Hypertension; Chongqing; China
| | - B. Nürnberg
- Institut für Experimentelle & Klinische Pharmakologie & Toxikologie and Interfaculty Center of Pharmacogenomics and Pharmaceutical Research (ICePhA); Eberhard-Karls-Universität; Tübingen; Germany
| | - M. Tepel
- Department of Nephrology, and University of Southern Denmark, Institute of Molecular Medicine, Cardiovascular and Renal Research, Institute of Clinical Research; Odense University Hospital; Odense; Denmark
| | - M. Gollasch
- Charité University Medicine, Section Nephrology/Intensive Care, Campus Virchow, and Experimental and Clinical Research Center (ECRC); Berlin; Germany
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Boychuk CR, Zsombok A, Tasker JG, Smith BN. Rapid Glucocorticoid-Induced Activation of TRP and CB1 Receptors Causes Biphasic Modulation of Glutamate Release in Gastric-Related Hypothalamic Preautonomic Neurons. Front Neurosci 2013; 7:3. [PMID: 23386808 PMCID: PMC3560102 DOI: 10.3389/fnins.2013.00003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 01/07/2013] [Indexed: 02/02/2023] Open
Abstract
Glucocorticoids rapidly regulate synaptic input to neuroendocrine cells in the hypothalamic paraventricular nucleus (PVN) by inducing the retrograde release of endogenous messengers. Here we investigated the rapid effects of dexamethasone (DEX) on excitatory synaptic input to feeding-related, preautonomic PVN neurons using whole-cell patch-clamp recordings. In ∼50% of identified gastric-related preautonomic PVN neurons, DEX elicited a biphasic synaptic response characterized by an initial rapid and transient increase in the frequency of miniature excitatory postsynaptic currents (mEPSCs), followed by a decrease in mEPSC frequency within 9 min; remaining cells displayed only a decrease in mEPSC frequency. The late-phase decrease in mEPSC frequency was mimicked by the cannabinoid receptor agonists anandamide (AEA) and WIN 55,212-2, and it was blocked by the CB1 receptor antagonist AM251. The biphasic DEX effect was mimicked by AEA. The early increase in mEPSCs was mimicked by activation of transient receptor potential vanilloid type 1 (TRPV1) receptors with capsaicin and by activation of TRPV4 receptors with 4-α-PDD. The increase was reduced, but not blocked, by selective TRPV1 antagonists and in TRPV1 knockout mice; it was blocked completely by the broad-spectrum TRPV antagonist ruthenium red and by combined application of selective TRPV1 and TRPV4 antagonists. The DEX effects were prevented entirely by intracellular infusion of the G-protein inhibitor, GDPβS. Thus, DEX biphasically modulates synaptic glutamate onto a subset of gastric-related PVN neurons, which is likely mediated by induction of a retrograde messenger. The effect includes a TRPV1/4 receptor-mediated transient increase and subsequent CB1 receptor-mediated suppression of glutamate release. Multiphasic modulation of glutamate input to PVN neurons represents a previously unappreciated complexity of control of autonomic output by glucocorticoids and endogenous cannabinoids.
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Affiliation(s)
- Carie R Boychuk
- Department of Physiology, University of Kentucky College of Medicine Lexington, KY, USA
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Cardoso LM, Colombari E, Toney GM. Endogenous hydrogen peroxide in the hypothalamic paraventricular nucleus regulates sympathetic nerve activity responses to L-glutamate. J Appl Physiol (1985) 2012; 113:1423-31. [PMID: 22984242 DOI: 10.1152/japplphysiol.00912.2012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The hypothalamic paraventricular nucleus (PVN) is important for maintenance of sympathetic nerve activity (SNA) and cardiovascular function. PVN-mediated increases of SNA often involve the excitatory amino acid L-glutamate (L-glu), whose actions can be positively and negatively modulated by a variety of factors, including reactive oxygen species. Here, we determined modulatory effects of the highly diffusible reactive oxygen species hydrogen peroxide (H(2)O(2)) on responses to PVN L-glu. Renal SNA (RSNA), arterial blood pressure, and heart rate were recorded in anesthetized rats. L-Glu (0.2 nmol in 100 nl) microinjected unilaterally into PVN increased RSNA (P < 0.05), without affecting mean arterial blood pressure or heart rate. Effects of endogenously generated H(2)O(2) were determined by comparing responses to PVN L-glu before and after PVN injection of the catalase inhibitor 3-amino-1,2,4-triazole (ATZ; 100 nmol/200 nl, n = 5). ATZ alone was without effect on recorded variables, but attenuated the increase of RSNA elicited by PVN L-glu (P < 0.05). PVN injection of exogenous H(2)O(2) (5 nmol in 100 nl, n = 4) and vehicle (artificial cerebrospinal fluid) were without affect, but H(2)O(2), like ATZ, attenuated the increase of RSNA to PVN L-glu (P < 0.05). Tonic effects of endogenous H(2)O(2) were determined by PVN injection of polyethylene glycol-catalase (1.0 IU in 200 nl, n = 5). Whereas polyethylene glycol-catalase alone was without effect, increases of RSNA to subsequent PVN injection of L-glu were increased (P < 0.05). From these data, we conclude that PVN H(2)O(2) tonically, but submaximally, suppresses RSNA responses to L-glu, supporting the idea that a change of H(2)O(2) availability within PVN could influence SNA regulation under physiological and/or disease conditions.
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Affiliation(s)
- Leonardo M Cardoso
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA
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