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Chen W, Cai W, Hoover B, Kahn CR. Insulin action in the brain: cell types, circuits, and diseases. Trends Neurosci 2022; 45:384-400. [PMID: 35361499 PMCID: PMC9035105 DOI: 10.1016/j.tins.2022.03.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 02/10/2022] [Accepted: 03/03/2022] [Indexed: 10/18/2022]
Abstract
Since its discovery over 100 years ago, insulin has been recognized as a key hormone in control of glucose homeostasis. Deficiencies of insulin signaling are central to diabetes and many other disorders. The brain is among the targets of insulin action, and insulin resistance is a major contributor to many diseases, including brain disorders. Here, we summarize key roles of insulin action in the brain and how this involves different brain cell types. Disordered brain insulin signaling can also contribute to neuropsychiatric diseases, affecting brain circuits involved in mood and cognition. Understanding of insulin signaling in different brain cell types/circuits and how these are altered in disease may lead to the development of new therapeutic approaches to these challenging disorders.
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Hernandez J, Perez L, Soto R, Le N, Gastelum C, Wagner EJ. Nociceptin/orphanin FQ neurons in the Arcuate Nucleus and Ventral Tegmental Area Act via Nociceptin Opioid Peptide Receptor Signaling to Inhibit Proopiomelanocortin and A 10 Dopamine Neurons and Thereby Modulate Ingestion of Palatable Food. Physiol Behav 2021; 228:113183. [PMID: 32979341 PMCID: PMC7736116 DOI: 10.1016/j.physbeh.2020.113183] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/13/2022]
Abstract
The neuropeptide nociceptin/orphanin FQ (N/OFQ) inhibits neuronal activity via its cognate nociceptin opioid peptide (NOP) receptor throughout the peripheral and central nervous systems, including those areas involved in the homeostatic and hedonic regulation of energy homeostasis. We thus tested the hypothesis that N/OFQ neurons in the hypothalamic arcuate nucleus (ARC) and ventral tegmental area (VTA) act via NOP receptor signaling to inhibit nearby anorexigenic proopiomelanocortin (POMC) and A10 dopamine neuronal excitability, respectively, and thereby modulate ingestion of palatable food. Electrophysiologic recordings were performed in slices prepared from transgenic male and ovariectomized (OVX) female N/OFQ-cre/enhanced green fluorescent protein-POMC, N/OFQ-cre and tyrosine hydroxylase-cre animals to see if optogenetically-stimulated peptide release from N/OFQ neurons could directly inhibit these neuronal populations. Binge-feeding behavioral experiments were also conducted where animals were exposed to a high-fat-diet (HFD) for one hour each day for five days and monitored for energy intake. Photostimulation of ARC and VTA N/OFQ neurons produces an outward current in POMC and A10 dopamine neurons receiving input from these cells. This is associated with a hyperpolarization and decreased firing. These features are also sex hormone- and diet-dependent; with estradiol-treated slices from OVX females being less sensitive, and obese males being more sensitive, to N/OFQ. Limited access to HFD causes a dramatic escalation in consumption, such that animals eat 25-45% of their daily intake during that one-hour exposure. Moreover, the NOP receptor-mediated regulation of these energy balance circuits are engaged, as N/OFQ injected directly into the VTA or ARC respectively diminishes or potentiates this binge-like increase in a manner heightened by diet-induced obesity or dampened by estradiol in females. Collectively, these findings provide key support for the idea that N/OFQ regulates appetitive behavior in sex-, site- and diet-specific ways, along with important insights into aberrant patterns of feeding behavior pertinent to the pathogenesis of food addiction.
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Affiliation(s)
- Jennifer Hernandez
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, USA
| | - Lynnea Perez
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA
| | - Rosy Soto
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, USA
| | - Nikki Le
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA
| | - Cassandra Gastelum
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA
| | - Edward J Wagner
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA, USA; College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, USA.
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Chang R, Hernandez J, Gastelum C, Guadagno K, Perez L, Wagner EJ. Pituitary Adenylate Cyclase-Activating Polypeptide Excites Proopiomelanocortin Neurons: Implications for the Regulation of Energy Homeostasis. Neuroendocrinology 2021; 111:45-69. [PMID: 32028278 DOI: 10.1159/000506367] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 01/30/2020] [Indexed: 11/19/2022]
Abstract
OBJECTIVE We examined whether pituitary adenylate cyclase-activating polypeptide (PACAP) excites proopiomelanocortin (POMC) neurons via PAC1 receptor mediation and transient receptor potential cation (TRPC) channel activation. METHODS Electrophysiological recordings were done in slices from both intact male and ovariectomized (OVX) female PACAP-Cre mice and eGFP-POMC mice. RESULTS In recordings from POMC neurons in eGFP-POMC mice, PACAP induced a robust inward current and increase in conductance in voltage clamp, and a depolarization and increase in firing in current clamp. These postsynaptic actions were abolished by inhibitors of the PAC1 receptor, TRPC channels, phospholipase C, phosphatidylinositol-3-kinase, and protein kinase C. Estradiol augmented the PACAP-induced inward current, depolarization, and increased firing, which was abrogated by estrogen receptor (ER) antagonists. In optogenetic recordings from POMC neurons in PACAP-Cre mice, high-frequency photostimulation induced inward currents, depolarizations, and increased firing that were significantly enhanced by Gq-coupled membrane ER signaling in an ER antagonist-sensitive manner. Importantly, the PACAP-induced excitation of POMC neurons was notably reduced in obese, high-fat (HFD)-fed males. In vivo experiments revealed that intra-arcuate nucleus (ARC) PACAP as well as chemogenetic and optogenetic stimulation of ventromedial nucleus (VMN) PACAP neurons produced a significant decrease in energy intake accompanied by an increase in energy expenditure, effects blunted by HFD in males and partially potentiated by estradiol in OVX females. CONCLUSIONS These findings reveal that the PACAP-induced activation of PAC1 receptor and TRPC5 channels at VMN PACAP/ARC POMC synapses is potentiated by estradiol and attenuated under conditions of diet-induced obesity/insulin resistance. As such, they advance our understanding of how PACAP regulates the homeostatic energy balance circuitry under normal and pathophysiological circumstances.
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Affiliation(s)
- Rachel Chang
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, California, USA
| | - Jennifer Hernandez
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California, USA
| | - Cassandra Gastelum
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, California, USA
| | - Kaitlyn Guadagno
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California, USA
| | - Lynnea Perez
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, California, USA
| | - Edward J Wagner
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, California, USA,
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, California, USA,
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Oghbaei H, Fattahi A, Hamidian G, Sadigh-Eteghad S, Ziaee M, Mahmoudi J. A closer look at the role of insulin for the regulation of male reproductive function. Gen Comp Endocrinol 2021; 300:113643. [PMID: 33017586 DOI: 10.1016/j.ygcen.2020.113643] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/16/2020] [Accepted: 09/28/2020] [Indexed: 11/25/2022]
Abstract
While insulin demonstrates to have a considerable influence on the reproductive system, there are various unanswered questions regarding its precise sites, mechanisms of action, and roles for the developing and functioning of the adult male reproductive system. Apart from its effects on glucose level, insulin has an important role in the reproductive system directly by binding on insulin and IGF receptors in the brain and testis. To date, however, the effect of insulin or its alterations on blood-testis-barrier, as an important regulator of normal spermatogenesis and fertility, has not yet been studied. This review aimed to focus on the experimental and clinical studies to describe mechanisms by which insulin affects the hypothalamic-pituitary-gonadal (HPG) axis, testicular cells, spermatozoa, and sexual behavior. Moreover, we discussed the mechanism and impact of insulin changes in type 1 (insulin deficiency along with persisted or even increased sensitivity) and 2 (insulin resistance along with increased insulin level at the early stages of disease) diabetes and obesity on the male reproductive tract.
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Affiliation(s)
- Hajar Oghbaei
- Department of Physiology, Tabriz University of Medical Sciences, Tabriz, Iran; Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Amir Fattahi
- Department of Reproductive Biology, School of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - GholamReza Hamidian
- Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran
| | - Saeed Sadigh-Eteghad
- Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mojtaba Ziaee
- Medicinal Plants Research Center, Maragheh University of Medical Sciences, Maragheh, Iran
| | - Javad Mahmoudi
- Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
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Effects of metabolic state on the regulation of melanocortin circuits. Physiol Behav 2020; 224:113039. [PMID: 32610101 PMCID: PMC7387173 DOI: 10.1016/j.physbeh.2020.113039] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 06/01/2020] [Accepted: 06/26/2020] [Indexed: 12/14/2022]
Abstract
Dysfunction in neurophysiological systems that regulate food intake and metabolism are at least partly responsible for obesity and related comorbidities. An important component of this process is the hypothalamic melanocortin system, where an imbalance can result in severe obesity and deficits in glucose metabolism. Exercise offers many health benefits related to cardiovascular improvements, hunger control, and blood glucose homeostasis. However, the molecular mechanism underlying the exercise-induced improvements to the melanocortin system remain undefined. Here, we review the role of the melanocortin system to sense hormonal, nutrient, and neuronal signals of energy status. This information is then relayed onto secondary neurons in order to regulate physiological parameters, which promote proper energy and glucose balance. We also provide an overview on the effects of physical exercise to induce biophysical changes in the melanocortin circuit which may regulate food intake, glucose metabolism and improve overall metabolic health.
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Pydi SP, Cui Z, He Z, Barella LF, Pham J, Cui Y, Oberlin DJ, Egritag HE, Urs N, Gavrilova O, Schwartz GJ, Buettner C, Williams KW, Wess J. Beneficial metabolic role of β-arrestin-1 expressed by AgRP neurons. SCIENCE ADVANCES 2020; 6:eaaz1341. [PMID: 32537493 PMCID: PMC7269658 DOI: 10.1126/sciadv.aaz1341] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 04/02/2020] [Indexed: 05/03/2023]
Abstract
β-Arrestin-1 and β-arrestin-2 have emerged as important signaling molecules that modulate glucose fluxes in several peripheral tissues. The potential roles of neuronally expressed β-arrestins in regulating glucose homeostasis remain unknown. We here report that mice lacking β-arrestin-1 (barr1) selectively in AgRP neurons displayed impaired glucose tolerance and insulin sensitivity when consuming an obesogenic diet, while mice overexpressing barr1 selectively in AgRP neurons were protected against obesity-associated metabolic impairments. Additional physiological, biochemical, and electrophysiological data indicated that the presence of barr1 is essential for insulin-mediated hyperpolarization of AgRP neurons. As a result, barr1 expressed by AgRP neurons regulates efferent neuronal pathways that suppress hepatic glucose production and promote lipolysis in adipose tissue. Mice lacking β-arrestin-2 (barr2) selectively in AgRP neurons showed no substantial metabolic phenotypes. Our data suggest that agents able to enhance the activity of barr1 in AgRP neurons may prove beneficial as antidiabetic drugs.
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Affiliation(s)
- Sai P. Pydi
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Zhenzhong Cui
- Mouse Metabolism Core, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Zhenyan He
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Luiz F. Barella
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Jonathan Pham
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Yinghong Cui
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Douglas J. Oberlin
- Diabetes, Obesity and Metabolism Institute, Mount Sinai School of Medicine, New York, NY 10029, USA
| | - Hale Ergin Egritag
- Diabetes, Obesity and Metabolism Institute, Mount Sinai School of Medicine, New York, NY 10029, USA
| | - Nikhil Urs
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, USA
| | - Oksana Gavrilova
- Mouse Metabolism Core, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Gary J. Schwartz
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Christoph Buettner
- Diabetes, Obesity and Metabolism Institute, Mount Sinai School of Medicine, New York, NY 10029, USA
| | - Kevin W. Williams
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Jürgen Wess
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
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He Z, Gao Y, Lieu L, Afrin S, Cao J, Michael NJ, Dong Y, Sun J, Guo H, Williams KW. Direct and indirect effects of liraglutide on hypothalamic POMC and NPY/AgRP neurons - Implications for energy balance and glucose control. Mol Metab 2019; 28:120-134. [PMID: 31446151 PMCID: PMC6822260 DOI: 10.1016/j.molmet.2019.07.008] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 07/22/2019] [Accepted: 07/25/2019] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVE The long-acting glucagon-like peptide-1 receptor (GLP-1R) agonist, liraglutide, stimulates insulin secretion and efficiently suppresses food intake to reduce body weight. As such, liraglutide is growing in popularity in the treatment of diabetes and chronic weight management. Within the brain, liraglutide has been shown to alter the activity of hypothalamic proopiomelanocortin (POMC) and Neuropeptide Y/Agouti-related peptide (NPY/AgRP) neurons. Moreover, the acute activities of POMC and NPY neurons have been directly linked to feeding behavior, body weight, and glucose metabolism. Despite the increased usage of liraglutide and other GLP-1 analogues as diabetic and obesity interventions, the cellular mechanisms by which liraglutide alters the activity of metabolically relevant neuronal populations are poorly understood. METHODS In order to resolve this issue, we utilized neuron-specific transgenic mouse models to identify POMC and NPY neurons for patch-clamp electrophysiology experiments. RESULTS We found that liraglutide directly activated arcuate POMC neurons via TrpC5 channels, sharing a similar mechanistic pathway to the adipose-derived peptide leptin. Liraglutide also indirectly increases excitatory tone to POMC neurons. In contrast, liraglutide inhibited NPY/AgRP neurons through post-synaptic GABAA receptors and enhanced activity of pre-synaptic GABAergic neurons, which required both TrpC5 subunits and K-ATP channels. In support of an additive role of leptin and liraglutide in suppressing food intake, leptin potentiated the acute effects of liraglutide to activate POMC neurons. TrpC5 subunits in POMC neurons were also required for the intact pharmacological effects of liraglutide on food intake and body weight. Thus, the current study adds to recent work from our group and others, which highlight potential mechanisms to amplify the effects of GLP-1 agonists in vivo. Moreover, these data highlight multiple sites of action (both pre- and post-synaptic) for GLP-1 agonists on this circuit. CONCLUSIONS Taken together, our results identify critical molecular mechanisms linking GLP-1 analogues in arcuate POMC and NPY/AgRP neurons with metabolism.
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Affiliation(s)
- Zhenyan He
- The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Division of Hypothalamic Research, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Yong Gao
- Division of Hypothalamic Research, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA; National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
| | - Linh Lieu
- Division of Hypothalamic Research, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Sadia Afrin
- Division of Hypothalamic Research, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Jianhong Cao
- Division of Hypothalamic Research, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA; Pi-wei Institute, Guangzhou University of Chinese Medicine, 12 Jichang Road, Guangzhou 510405, China
| | - Natalie J Michael
- Division of Hypothalamic Research, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Yanbin Dong
- Division of Hypothalamic Research, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA; Pi-wei Institute, Guangzhou University of Chinese Medicine, 12 Jichang Road, Guangzhou 510405, China
| | - Jia Sun
- Division of Hypothalamic Research, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Hongbo Guo
- The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Kevin W Williams
- Division of Hypothalamic Research, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA.
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He Z, Gao Y, Lieu L, Afrin S, Guo H, Williams KW. Acute effects of zinc and insulin on arcuate anorexigenic proopiomelanocortin neurons. Br J Pharmacol 2019; 176:725-736. [PMID: 30521677 PMCID: PMC6365359 DOI: 10.1111/bph.14559] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 11/15/2018] [Accepted: 11/24/2018] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND AND PURPOSE Acute insulin administration hyperpolarized, with concomitant decrease of firing rate, a subpopulation of arcuate proopiomelanocortin (POMC) and neuropeptide Y/agouti-related peptide cells. This rapid effect on cellular activity has been proposed as a cellular correlate of insulin effects on energy balance and glucose homoeostasis. Recent evidence suggests that zinc in mammalian insulin formulations is required for the insulin-induced inhibition of arcuate POMC neurons, while guinea pig insulin, which fails to bind zinc, activates POMC neurons in mice. Here, we tested the effects of zinc and insulin formations on arcuate POMC neurons. EXPERIMENTAL APPROACH Effects of zinc and insulin formulations were assessed through whole-cell patch clamp recordings on transgenic mice in vitro. KEY RESULTS Insulin formulations containing zinc hyperpolarized POMC neurons. Zinc also hyperpolarized arcuate POMC neurons, albeit at much higher concentration than found in various insulin formulations. Chelation of zinc inhibited the zinc-induced hyperpolarization of POMC neurons, whereas effects of insulin on POMC cellular activity were unchanged after chelation. Zinc-free insulin also hyperpolarized arcuate POMC neurons. Insulin failed to hyperpolarize POMC neurons deficient for insulin receptors, suggesting that insulin receptors are required for these effects. Activation of POMC neurons by guinea pig insulin was independent of insulin receptors but was inhibited by PDGF receptor antagonism or loss of TRPC5 channel subunits. CONCLUSIONS AND IMPLICATIONS Together, these findings suggest that insulin inhibited arcuate POMC neurons independent of zinc and highlights a possible role of putative PDGF receptors in the acute effects of guinea pig insulin.
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Affiliation(s)
- Zhenyan He
- The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang HospitalSouthern Medical UniversityGuangzhouChina
- Division of Hypothalamic Research, Department of Internal MedicineThe University of Texas Southwestern Medical Center at DallasDallasTXUSA
| | - Yong Gao
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical SciencesChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina
- Division of Hypothalamic Research, Department of Internal MedicineThe University of Texas Southwestern Medical Center at DallasDallasTXUSA
| | - Linh Lieu
- Division of Hypothalamic Research, Department of Internal MedicineThe University of Texas Southwestern Medical Center at DallasDallasTXUSA
| | - Sadia Afrin
- Division of Hypothalamic Research, Department of Internal MedicineThe University of Texas Southwestern Medical Center at DallasDallasTXUSA
| | - Hongbo Guo
- The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang HospitalSouthern Medical UniversityGuangzhouChina
| | - Kevin W Williams
- Division of Hypothalamic Research, Department of Internal MedicineThe University of Texas Southwestern Medical Center at DallasDallasTXUSA
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