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Kuboki A, Kikuta S, Otori N, Kojima H, Matsumoto I, Reisert J, Yamasoba T. Insulin-Dependent Maturation of Newly Generated Olfactory Sensory Neurons after Injury. eNeuro 2021; 8:ENEURO.0168-21.2021. [PMID: 33906971 PMCID: PMC8143024 DOI: 10.1523/eneuro.0168-21.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 04/20/2021] [Indexed: 12/24/2022] Open
Abstract
Loss of olfactory sensory neurons (OSNs) after injury to the olfactory epithelium (OE) triggers the generation of OSNs that are incorporated into olfactory circuits to restore olfactory sensory perception. This study addresses how insulin receptor-mediated signaling affects the functional recovery of OSNs after OE injury. Insulin levels were reduced in mice by ablating the pancreatic β cells via streptozotocin (STZ) injections. These STZ-induced diabetic and control mice were then intraperitoneally injected with the olfactotoxic drug methimazole to selectively ablate OSNs. The OE of diabetic and control mice regenerated similarly until day 14 after injury. Thereafter, the OE of diabetic mice contained fewer mature and more apoptotic OSNs than control mice. Functionally, diabetic mice showed reduced electro-olfactogram (EOG) responses and their olfactory bulbs (OBs) had fewer c-Fos-active cells following odor stimulation, as well as performed worse in an odor-guided task compared with control mice. Insulin administered intranasally during days 8-13 after injury was sufficient to rescue recovery of OSNs in diabetic mice compared with control levels, while insulin administration between days 1 and 6 did not. During this critical time window on days 8-13 after injury, insulin receptors are highly expressed and intranasal application of an insulin receptor antagonist inhibits regeneration. Furthermore, an insulin-enriched environment could facilitate regeneration even in non-diabetic mice. These results indicate that insulin facilitates the regeneration of OSNs after injury and suggest a critical stage during recovery (8-13 d after injury) during which the maturation of newly generated OSNs is highly dependent on and promoted by insulin.
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Affiliation(s)
- Akihito Kuboki
- Department of Otolaryngology, Jikei University School of Medicine, Tokyo 105-8461, Japan
- Monell Chemical Senses Center, Philadelphia, PA 19104
| | - Shu Kikuta
- Department of Otolaryngology, Graduate School of Medicine, University of Tokyo, Tokyo 113-8655, Japan
| | - Nobuyoshi Otori
- Department of Otolaryngology, Jikei University School of Medicine, Tokyo 105-8461, Japan
| | - Hiromi Kojima
- Department of Otolaryngology, Jikei University School of Medicine, Tokyo 105-8461, Japan
| | | | | | - Tatsuya Yamasoba
- Department of Otolaryngology, Graduate School of Medicine, University of Tokyo, Tokyo 113-8655, Japan
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2
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Pedro JR, Moura LIF, Valério-Fernandes Â, Baptista FI, Gaspar JM, Pinheiro BS, Lemos C, Kaufmann FN, Morgado C, Silva-Santos CSD, Tavares I, Ferreira SG, Carvalho E, Ambrósio AF, Cunha RA, Duarte JMN, Köfalvi A. Transient gain of function of cannabinoid CB 1 receptors in the control of frontocortical glucose consumption in a rat model of Type-1 diabetes. Brain Res Bull 2020; 161:106-115. [PMID: 32428627 DOI: 10.1016/j.brainresbull.2020.05.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/23/2020] [Accepted: 05/04/2020] [Indexed: 12/31/2022]
Abstract
Here we aimed to unify some previous controversial reports on changes in both cannabinoid CB1 receptor (CB1R) expression and glucose metabolism in the forebrain of rodent models of diabetes. We determined how glucose metabolism and its modulation by CB1R ligands evolve in the frontal cortex of young adult male Wistar rats, in the first 8 weeks of streptozotocin-induced type-1 diabetes (T1D). We report that frontocortical CB1R protein density was biphasically altered in the first month of T1D, which was accompanied with a reduction of resting glucose uptake ex vivo in acute frontocortical slices that was normalized after eight weeks in T1D. This early reduction of glucose uptake in slices was also restored by ex vivo treatment with both the non-selective CB1R agonists, WIN55212-2 (500 nM) and the CB1R-selective agonist, ACEA (3 μM) while it was exacerbated by the CB1R-selective antagonist, O-2050 (500 nM). These results suggest a gain-of-function for the cerebrocortical CB1Rs in the control of glucose uptake in diabetes. Although insulin and IGF-1 receptor protein densities remained unaffected, phosphorylated GSKα and GSKβ levels showed different profiles 2 and 8 weeks after T1D induction in the frontal cortex. Altogether, the biphasic response in frontocortical CB1R density within a month after T1D induction resolves previous controversial reports on forebrain CB1R levels in T1D rodent models. Furthermore, this study also hints that cannabinoids may be useful to alleviate impaired glucoregulation in the diabetic cortex.
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Affiliation(s)
- Joana Reis Pedro
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Liane I F Moura
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Ângela Valério-Fernandes
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, 3030-789 Coimbra, Portugal
| | - Filipa I Baptista
- Coimbra Institute for Clinical and Biomedical Research, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Joana M Gaspar
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Bárbara S Pinheiro
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Cristina Lemos
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | | | - Carla Morgado
- Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Carla S da Silva-Santos
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Isaura Tavares
- Department of Biomedicine, Faculty of Medicine, University of Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal; I3S Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal
| | - Samira G Ferreira
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Eugénia Carvalho
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, 3030-789 Coimbra, Portugal; The Portuguese Diabetes Association (APDP), Lisbon, Portugal; Arkansas Children's Research Institute, and Department of Geriatrics, University of Arkansas for Medical Sciences, Arkansas 72205, United States
| | - António F Ambrósio
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Coimbra Institute for Clinical and Biomedical Research, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; Association for Innovation and Biomedical Research on Light and Image (AIBILI), 3000-548 Coimbra, Portugal
| | - Rodrigo A Cunha
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - João M N Duarte
- Department of Experimental Medical Science, Faculty of Medicine, Lund University, Lund, Sweden; Wallenberg Centre for Molecular Medicine, Lund University, Lund, Sweden
| | - Attila Köfalvi
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, 3030-789 Coimbra, Portugal.
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Sergi D, Renaud J, Simola N, Martinoli MG. Diabetes, a Contemporary Risk for Parkinson's Disease: Epidemiological and Cellular Evidences. Front Aging Neurosci 2019; 11:302. [PMID: 31787891 PMCID: PMC6856011 DOI: 10.3389/fnagi.2019.00302] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 10/22/2019] [Indexed: 12/14/2022] Open
Abstract
Diabetes mellitus (DM), a group of diseases characterized by defective glucose metabolism, is the most widespread metabolic disorder affecting over 400 million adults worldwide. This pathological condition has been implicated in the pathogenesis of a number of central encephalopathies and peripheral neuropathies. In further support of this notion, recent epidemiological evidence suggests a link between DM and Parkinson’s disease (PD), with hyperglycemia emerging as one of the culprits in neurodegeneration involving the nigrostriatal pathway, the neuroanatomical substrate of the motor symptoms affecting parkinsonian patients. Indeed, dopaminergic neurons located in the mesencephalic substantia nigra appear to be particularly vulnerable to oxidative stress and degeneration, likely because of their intrinsic susceptibility to mitochondrial dysfunction, which may represent a direct consequence of hyperglycemia and hyperglycemia-induced oxidative stress. Other pathological pathways induced by increased intracellular glucose levels, including the polyol and the hexosamine pathway as well as the formation of advanced glycation end-products, may all play a pivotal role in mediating the detrimental effects of hyperglycemia on nigral dopaminergic neurons. In this review article, we will examine the epidemiological as well as the molecular and cellular clues supporting the potential susceptibility of nigrostriatal dopaminergic neurons to hyperglycemia.
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Affiliation(s)
- Domenico Sergi
- Nutrition and Health Substantiation Group, Nutrition and Health Program, Health and Biosecurity, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Adelaide, SA, Australia.,Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Justine Renaud
- Cellular Neurobiology, Department of Medical Biology, Université du Québec, Trois-Rivières, QC, Canada
| | - Nicola Simola
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy.,National Institute for Neuroscience (INN), University of Cagliari, Cagliari, Italy
| | - Maria-Grazia Martinoli
- Cellular Neurobiology, Department of Medical Biology, Université du Québec, Trois-Rivières, QC, Canada.,Department of Psychiatry and Neuroscience, Université Laval and CHU Research Center, Québec, QC, Canada
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Pinheiro BS, Lemos C, Neutzling Kaufmann F, Marques JM, da Silva-Santos CS, Carvalho E, Mackie K, Rodrigues RJ, Cunha RA, Köfalvi A. Hierarchical glucocorticoid-endocannabinoid interplay regulates the activation of the nucleus accumbens by insulin. Brain Res Bull 2016; 124:222-30. [PMID: 27208730 DOI: 10.1016/j.brainresbull.2016.05.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 05/16/2016] [Accepted: 05/17/2016] [Indexed: 12/28/2022]
Abstract
Here we asked if insulin activation of the nucleus accumbens in vitro is reflected by an increase in (3)H-deoxyglucose ([(3)H]DG) uptake, thus subserving a new model to study molecular mechanisms of central insulin actions. Additionally, we investigated the dependence of this insulin effect on endocannabinoids and corticosteroids, two major culprits in insulin resistance. We found that in acute accumbal slices, insulin (3 and 300nM but not at 0.3nM) produced an increase in [(3)H]DG uptake. The synthetic cannabinoid agonist, WIN55212-2 (500nM) and the glucocorticoid dexamethasone (10μM), impaired insulin (300nM) action on [(3)H]DG uptake. The glucocorticoid receptor (GcR) antagonist, mifepristone (10μM) prevented dexamethasone from inhibiting insulin's action. Strikingly, this anti-insulin action of dexamethasone was also blocked by two CB1 cannabinoid receptor (CB1R) antagonists, O-2050 (500nM) and SR141716A (500nM), as well as by tetrahydrolipstatin (10μM), an inhibitor of diacylglycerol lipases-the enzymes responsible for the synthesis of the endocannabinoid, 2-arachidonoyl-glycerol (2-AG). On the other hand, the blockade of the post-synaptic 2-AG metabolizing enzymes, α,β-serine hydrolase domain 6/12 by WWL70 (1μM) also prevented the action of insulin, probably via increasing endogenous 2-AG tone. Additionally, an anti-insulin receptor (InsR) antibody immunoprecipitated CB1Rs from accumbal homogenates, indicating a physical complexing of CB1Rs with InsRs that supports their functional interaction. Altogether, insulin stimulates glucose uptake in the nucleus accumbens. Accumbal GcR activation triggers the synthesis of 2-AG that in turn binds to the known CB1R-InsR heteromer, thus impeding insulin signaling.
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Affiliation(s)
- Bárbara S Pinheiro
- CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Cristina Lemos
- CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal
| | | | - Joana M Marques
- CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Carla S da Silva-Santos
- CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Eugénia Carvalho
- CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Ken Mackie
- Department of Psychological and Brain Sciences, Gill Center for Biomolecular Science, Indiana University, Bloomington, IN, USA
| | - Ricardo J Rodrigues
- CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, 3030-789 Coimbra, Portugal
| | - Rodrigo A Cunha
- CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal; FMUC, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Attila Köfalvi
- CNC, Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, 3004-504 Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, 3030-789 Coimbra, Portugal.
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Caravaggio F, Hahn M, Nakajima S, Gerretsen P, Remington G, Graff-Guerrero A. Reduced insulin-receptor mediated modulation of striatal dopamine release by basal insulin as a possible contributing factor to hyperdopaminergia in schizophrenia. Med Hypotheses 2015; 85:391-6. [PMID: 26118462 DOI: 10.1016/j.mehy.2015.06.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 05/22/2015] [Accepted: 06/17/2015] [Indexed: 12/23/2022]
Abstract
Schizophrenia is a severe and chronic neuropsychiatric disorder which affects 1% of the world population. Using the brain imaging technique positron emission tomography (PET) it has been demonstrated that persons with schizophrenia have greater dopamine transmission in the striatum compared to healthy controls. However, little progress has been made as to elucidating other biological mechanisms which may account for this hyperdopaminergic state in this disease. Studies in animals have demonstrated that insulin receptors are expressed on midbrain dopamine neurons, and that insulin from the periphery acts on these receptors to modify dopamine transmission in the striatum. This is pertinent given that several lines of evidence suggest that insulin receptor functioning may be abnormal in the brains of persons with schizophrenia. Post-mortem studies have shown that persons with schizophrenia have less than half the number of cortical insulin receptors compared to healthy persons. Moreover, these post-mortem findings are unlikely due to the effects of antipsychotic treatment; studies in cell lines and animals suggest antipsychotics enhance insulin receptor functioning. Further, hyperinsulinemia - even prior to antipsychotic use - seems to be related to less psychotic symptoms in patients with schizophrenia. Collectively, these data suggest that midbrain insulin receptor functioning may be abnormal in persons with schizophrenia, resulting in reduced insulin-mediated regulation of dopamine transmission in the striatum. Such a deficit may account for the hyperdopaminergic state observed in these patients and would help guide the development of novel treatment strategies. We hypothesize that, (i) insulin receptor expression and/or function is reduced in midbrain dopamine neurons in persons with schizophrenia, (ii) basal insulin should reduce dopaminergic transmission in the striatum via these receptors, and (iii) this modulation of dopaminergic transmission by basal insulin is reduced in the brains of persons with schizophrenia.
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Affiliation(s)
- Fernando Caravaggio
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario M5T 1R8, Canada; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Margaret Hahn
- Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario M5T 1R8, Canada
| | - Shinichiro Nakajima
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario M5T 1R8, Canada; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario M5T 1R8, Canada
| | - Philip Gerretsen
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario M5T 1R8, Canada; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario M5T 1R8, Canada
| | - Gary Remington
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario M5T 1R8, Canada; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario M5T 1R8, Canada
| | - Ariel Graff-Guerrero
- Research Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario M5T 1R8, Canada; Institute of Medical Science, University of Toronto, 2374 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario M5T 1R8, Canada.
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Blázquez E, Velázquez E, Hurtado-Carneiro V, Ruiz-Albusac JM. Insulin in the brain: its pathophysiological implications for States related with central insulin resistance, type 2 diabetes and Alzheimer's disease. Front Endocrinol (Lausanne) 2014; 5:161. [PMID: 25346723 PMCID: PMC4191295 DOI: 10.3389/fendo.2014.00161] [Citation(s) in RCA: 316] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 09/21/2014] [Indexed: 12/21/2022] Open
Abstract
Although the brain has been considered an insulin-insensitive organ, recent reports on the location of insulin and its receptors in the brain have introduced new ways of considering this hormone responsible for several functions. The origin of insulin in the brain has been explained from peripheral or central sources, or both. Regardless of whether insulin is of peripheral origin or produced in the brain, this hormone may act through its own receptors present in the brain. The molecular events through which insulin functions in the brain are the same as those operating in the periphery. However, certain insulin actions are different in the central nervous system, such as hormone-induced glucose uptake due to a low insulin-sensitive GLUT-4 activity, and because of the predominant presence of GLUT-1 and GLUT-3. In addition, insulin in the brain contributes to the control of nutrient homeostasis, reproduction, cognition, and memory, as well as to neurotrophic, neuromodulatory, and neuroprotective effects. Alterations of these functional activities may contribute to the manifestation of several clinical entities, such as central insulin resistance, type 2 diabetes mellitus (T2DM), and Alzheimer's disease (AD). A close association between T2DM and AD has been reported, to the extent that AD is twice more frequent in diabetic patients, and some authors have proposed the name "type 3 diabetes" for this association. There are links between AD and T2DM through mitochondrial alterations and oxidative stress, altered energy and glucose metabolism, cholesterol modifications, dysfunctional protein O-GlcNAcylation, formation of amyloid plaques, altered Aβ metabolism, and tau hyperphosphorylation. Advances in the knowledge of preclinical AD and T2DM may be a major stimulus for the development of treatment for preventing the pathogenic events of these disorders, mainly those focused on reducing brain insulin resistance, which is seems to be a common ground for both pathological entities.
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Affiliation(s)
- Enrique Blázquez
- Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense, Madrid, Spain
- The Center for Biomedical Research in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdiSSC), Madrid, Spain
- *Correspondence: Enrique Blázquez, Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense de Madrid, Plaza Ramón y Cajal s/n, Madrid 28040, Spain e-mail:
| | - Esther Velázquez
- Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense, Madrid, Spain
- The Center for Biomedical Research in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdiSSC), Madrid, Spain
| | - Verónica Hurtado-Carneiro
- Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense, Madrid, Spain
- The Center for Biomedical Research in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdiSSC), Madrid, Spain
| | - Juan Miguel Ruiz-Albusac
- Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense, Madrid, Spain
- The Center for Biomedical Research in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdiSSC), Madrid, Spain
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Ghasemi R, Haeri A, Dargahi L, Mohamed Z, Ahmadiani A. Insulin in the brain: sources, localization and functions. Mol Neurobiol 2012; 47:145-71. [PMID: 22956272 DOI: 10.1007/s12035-012-8339-9] [Citation(s) in RCA: 190] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 08/20/2012] [Indexed: 02/07/2023]
Abstract
Historically, insulin is best known for its role in peripheral glucose homeostasis, and insulin signaling in the brain has received less attention. Insulin-independent brain glucose uptake has been the main reason for considering the brain as an insulin-insensitive organ. However, recent findings showing a high concentration of insulin in brain extracts, and expression of insulin receptors (IRs) in central nervous system tissues have gathered considerable attention over the sources, localization, and functions of insulin in the brain. This review summarizes the current status of knowledge of the peripheral and central sources of insulin in the brain, site-specific expression of IRs, and also neurophysiological functions of insulin including the regulation of food intake, weight control, reproduction, and cognition and memory formation. This review also considers the neuromodulatory and neurotrophic effects of insulin, resulting in proliferation, differentiation, and neurite outgrowth, introducing insulin as an attractive tool for neuroprotection against apoptosis, oxidative stress, beta amyloid toxicity, and brain ischemia.
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Affiliation(s)
- Rasoul Ghasemi
- Department of Physiology, Faculty of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
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8
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Insulin dysfunction induces in vivo tau hyperphosphorylation through distinct mechanisms. J Neurosci 2008; 27:13635-48. [PMID: 18077675 DOI: 10.1523/jneurosci.3949-07.2007] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Hyperphosphorylated tau is the major component of paired helical filaments in neurofibrillary tangles found in Alzheimer's disease (AD) brains, and tau hyperphosphorylation is thought to be a critical event in the pathogenesis of the disease. The large majority of AD cases is late onset and sporadic in origin, with aging as the most important risk factor. Insulin resistance, impaired glucose tolerance, and diabetes mellitus (DM) are other common syndromes in the elderly also strongly age dependent, and there is evidence supporting a link between insulin dysfunction and AD. To investigate the possibility that insulin dysfunction might promote tau pathology, we induced insulin deficiency and caused DM in mice with streptozotocin (STZ). A mild hyperphosphorylation of tau could be detected 10, 20, and 30 d after STZ injection, and a massive hyperphosphorylation of tau was observed after 40 d. The robust hyperphosphorylation of tau was localized in the axons and neuropil, and prevented tau binding to microtubules. Neither mild nor massive tau phosphorylation induced tau aggregation. Body temperature of the STZ-treated mice did not differ from control animals during 30 d, but dropped significantly thereafter. No change in beta-amyloid (Abeta) precursor protein (APP), APP C-terminal fragments, or Abeta levels were observed in STZ-treated mice; however, cellular protein phosphatase 2A activity was significantly decreased. Together, these data indicate that insulin dysfunction induced abnormal tau hyperphosphorylation through two distinct mechanisms: one was consequent to hypothermia; the other was temperature-independent, inherent to insulin depletion, and probably caused by inhibition of phosphatase activity.
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9
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Peddyreddy MK, Rao KR. Peripheral and centrally mediated effects of insulin on small intestinal transit in healthy mice. Clin Exp Pharmacol Physiol 2006; 33:633-6. [PMID: 16789932 DOI: 10.1111/j.1440-1681.2006.04427.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
1. Insulin is the drug of choice in the management of type 1 diabetes mellitus. Approximately 76% of diabetic patients suffer from gastrointestinal disorders. An important area of investigating the inherent effect of insulin on small intestinal transit (SIT) remains unexplored. Hence, the present study was planned to investigate the effects of insulin (2 x 10(-6), 2 x 10(-3) and 2 U/kg) on small intestinal transit following two different routes of administration in healthy animals. 2. Insulin or vehicle was administered subcutaneously or intracerebroventricularly in eight groups of healthy, overnight-fasted mice. Blood glucose (BG) levels were measured 2 min before insulin administration and at the time coinciding with SIT determination. Small intestinal transit was determined 50 min after insulin administration using the charcoal meal method. 3. Following subcutaneous administration, the lowest dose of insulin (2 x 10(-6) U/kg) produced a significant acceleration in SIT without altering BG levels. However, the highest dose of insulin (2 U/kg) produced an acceleration of SIT that was associated with a significant fall in BG levels. 4. Following intracerebroventricular administration, the lowest dose of insulin (2 x 10(-6) U/kg) attenuated SIT, without producing any alteration in BG levels, but the highest dose (2 U/kg) mimicked the effects seen following subcutaneous administration. Peripherally administered insulin produced significant acceleration of SIT at lower doses (2 x 10(-6) or 2 x 10(-3) mU/kg) compared with centrally administered insulin at similar doses. However, at the highest dose of insulin (2 U/kg), both routes (s.c. and i.c.v.) produced acceleration of SIT. 5. In the present study, peripherally and centrally administered insulin at 2 x 10(-6) U/kg produced contrasting effects on SIT, without any hypoglycaemia. However, 2 U/kg insulin accelerated SIT similarly following both s.c. and i.c.v. administration that was associated with hypoglycaemia in healthy animals.
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Affiliation(s)
- M K Peddyreddy
- Department of Anatomy, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India.
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10
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Karagiannis SN, King RH, Thomas PK. Colocalisation of insulin and IGF-1 receptors in cultured rat sensory and sympathetic ganglion cells. J Anat 1997; 191 ( Pt 3):431-40. [PMID: 9419000 PMCID: PMC1467700 DOI: 10.1046/j.1469-7580.1997.19130431.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Peripheral sensory and autonomic neurons are known to possess insulin receptors. These have been considered to be of the peripheral type, i.e. similar to those of hepatic and fat cells rather than of the brain type which show dual specificity for both insulin and insulin-like growth factor (IGF-1). We have examined the localisation of insulin and IGF-1 receptors in cultured sensory and sympathetic ganglion cells using confocal microscopy and indirect labelling with FITC (fluorescein isothiocyanate) and TRITC (tetramethyl rhodamine isothiocyanate) respectively. We have shown that in cultured U266B1 multiple myeloma cells these receptors display separate localisation, whereas they are colocalised in IM-9 lymphocytes which are known to possess hybrid receptors. We have confirmed the sequestration of insulin and IGF-1 receptors in the cytoplasm of sensory and sympathetic neurons, consistent with a brain-type receptor. The colocalisation of insulin and IGF-1 receptors in sensory and sympathetic ganglion cells is consistent with the view that they are hybrid receptors, similar to those present in the CNS. The function of these receptors, as suggested for the CNS, may be related to trophic support for neurons.
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MESH Headings
- Animals
- Cell Line
- Cells, Cultured
- Fluorescent Antibody Technique, Indirect
- Ganglia, Sensory/chemistry
- Ganglia, Sensory/cytology
- Ganglia, Sympathetic/chemistry
- Ganglia, Sympathetic/cytology
- Humans
- Microscopy, Confocal
- Rats
- Rats, Sprague-Dawley
- Receptor, IGF Type 1/analysis
- Receptor, Insulin/analysis
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Affiliation(s)
- S N Karagiannis
- Department of Clinical Neurosciences, Royal Free Hospital School of Medicine, London, UK
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11
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Pezzino V, Costantino A, Russo P, Gullo D, Papa V. Insulin receptor content in tissues of normal and diabetic rats measured by radioimmunoassay. J Endocrinol Invest 1996; 19:593-7. [PMID: 8957742 DOI: 10.1007/bf03349023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Insulin receptor (IR) content in different tissues has been quantitatively evaluated by means of steady state binding studies with radiolabeled insulin. The information provided by this approach, however, does not give a direct measurement of the receptor protein. Rather, it depends on the binding function of the IR, evaluated on the basis of curvilinear plots derived by Scatchard analysis of the experimental data. In the present report we employed a sensitive and specific radioimmunoassay (RIA) that allows a direct measurement of IR in solubilized cells or tissues. By this method we studied: a) IR distribution in several tissues of the rat, the animal model most frequently used in studies of insulin action; b) IR regulation in streptozotocin-treated, diabetic insulin deficient rats. Tissues from male Wistar rats (11 controls and 6 streptozotocin-treated diabetic animals) were homogenized, solubilized with Triton X-100 in the presence of protease inhibitors and stored at -80 C. IR content in the solubilized material was then measured by RIA. IR were detectable in all 11 tissues tested. Liver, kidney and brain neocortex had the highest IR content. (24.7 +/- 1.0, 20.5 +/- 1.1, 25.9 +/- 1.6 ng/mg protein, m +/- SE, respectively). As expected, circulating insulin levels were lower in diabetic rats than in control rats. In diabetic, insulin deficient rats, liver, kidney and skeletal muscle contained more IR than in control rats (p = 0.001; p = 0.018; p = 0.003, respectively), whereas IR content in neocortex was similar in the two groups. The IR RIA may represent a useful tool for the study of IR regulation and patho-physiology. Our data provide a comparative direct measurement of IR distribution in a variety of rat tissues. IR content in diabetic rats is increased in typical target organs for insulin action, as a consequence of up-regulation due to the reduced insulin levels. This is not the case for metabolically insulin-dependent tissues, like brain.
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Affiliation(s)
- V Pezzino
- Cattedra di Endocrinologia, Università di Catania, Italy
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12
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Kotzke G, Schütt M, Missler U, Moller DE, Fehm HL, Klein HH. Binding of human, porcine and bovine insulin to insulin receptors from human brain, muscle and adipocytes and to expressed recombinant alternatively spliced insulin receptor isoforms. Diabetologia 1995; 38:757-63. [PMID: 7556975 DOI: 10.1007/s001250050349] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Previous studies have suggested that human and porcine insulin exert identical effects on blood glucose and counter-regulatory hormones but elicit different neurophysiological reactions. A major goal of the present study was to investigate whether this could be caused by different relative affinities of the insulins from different species to insulin receptors from the brain compared to other tissues. Insulin receptors isolated from human brain, muscle or adipocytes as well as from cultured cells over-expressing either of the human insulin receptor isoforms (exon 11- or exon 11 +) were immobilized to microwells coated with monoclonal anti-insulin receptor antibody. Subsequently the binding of human, porcine and bovine insulin was measured. While the receptors derived from the different tissues had different affinities for insulin, there were no tissue-specific differences in the relative binding of the insulins of the three species. The insulins of the three species were also not different with regard to their binding to the receptor isoforms. Finally, in human brain homogenates no differences in the degradation rates for human, porcine and bovine insulin were detected. Thus, our data do not support the hypothesis that different neurophysiological reactions during hypoglycaemia due to human or porcine insulin are caused by differences of the binding of the insulins to human brain insulin receptors or their degradation in the human brain.
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Affiliation(s)
- G Kotzke
- Department of Internal Medicine, University of Lübeck, Germany
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13
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Adamo ML, Shemer J, Roberts CT, LeRoith D. Insulin and insulin-like growth factor-I induced phosphorylation in neurally derived cells. Ann N Y Acad Sci 1993; 692:113-25. [PMID: 7692785 DOI: 10.1111/j.1749-6632.1993.tb26210.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- M L Adamo
- Diabetes Branch, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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14
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Voll CL, Auer RN. Insulin attenuates ischemic brain damage independent of its hypoglycemic effect. J Cereb Blood Flow Metab 1991; 11:1006-14. [PMID: 1939378 DOI: 10.1038/jcbfm.1991.168] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Insulin, an endogenously produced circulating peptide that enters the brain, has been shown to reduce ischemic brain and spinal cord damage in several animal models. Because of its potential clinical use in humans, the present study was undertaken to test the hypotheses that (a) survival and regional ischemic brain necrosis are improved by insulin; (b) insulin requires concomitant hypoglycemia to exert its neuroprotective effect; (c) insulin is still neuroprotective with delayed administration after an episode of postischemic hypotension; and (d) insulin is beneficial after normoglycemic, as well as hyperglycemic ischemia. Rats were subjected to 10.5 min two-vessel occlusion forebrain ischemia followed by 30 min of hypotension to increase the infarction rate. Insulin administered concomitantly with glucose significantly reduced the seizure rate, as well as cortical and striatal neuronal necrosis below that seen in untreated animals. Neuroprotection was seen whether insulin was given before or after a 30-min episode of postischemic hypotension. Insulin reduced pan-necrosis in addition to selective neuronal necrosis: The infarction rate was reduced in the cerebral cortex, thalamus, and substantia nigra pars reticulata. Normoglycemic ischemia produced only selective neuronal necrosis, but a beneficial effect on structural damage was also seen. The results indicate that insulin acts directly on the brain, independent of hypoglycemia, to reduce ischemic brain necrosis. Possible direct CNS mechanisms of action include an effect on central insulin receptors mediating inhibitory neuromodulation, an effect on central neurotransmitters, or a growth factor effect of insulin.
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Affiliation(s)
- C L Voll
- Department of Pathology, University of Calgary, Alberta, Canada
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15
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Svrzic D, Schubert D. Insulin-like growth factor 1 supports embryonic nerve cell survival. Biochem Biophys Res Commun 1990; 172:54-60. [PMID: 2222482 DOI: 10.1016/s0006-291x(05)80172-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Insulin-like growth factor 1 (IGF-1) is shown to support the long term survival of embryonic chicken central nervous system neurons cultured in a defined medium. This trophic activity for IGF-1 was discovered as the result of its presence as a contaminant in bovine serum albumin, a reagent frequently used in primary cultures of neuronal tissue. The observation that IGF-1 has cell survival activity may explain the high level of IGF-1 receptors found in embryonic brain.
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Affiliation(s)
- D Svrzic
- Salk Institute for Biological Studies, San Diego, CA 92138-9216
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16
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Insulin and insulinlike growth factor 1 (IGF-1) receptors during central nervous system development: expression of two immunologically distinct IGF-1 receptor beta subunits. Mol Cell Biol 1989. [PMID: 2476658 DOI: 10.1128/mcb.9.7.2806] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Insulin and insulinlike growth factor 1 (IGF-1) receptors are present in brain, yet their function remains obscure. Expression of these tyrosine kinase-bearing growth factor receptors during rat brain development was examined by using three antipeptide antibodies directed against epitopes in the beta subunits (AbP2, AbP4, and AbP5). All three antibodies recognized both insulin and IGF-1 receptors. Membranes were prepared from fetal brains (14 to 21 days of gestation), neonatal brain (postnatal day 1), and adult brain. Immunoblot analyses using AbP4 and AbP5 revealed a 92-kilodalton (kDa) protein that corresponded to the beta subunit of the insulin and IGF-1 receptors. Densitometric scanning of immunoblots indicated that receptor proteins were 4- to 10-fold more abundant in fetal brain membranes than in membranes from adult brain. Expression was highest during 16 to 18 days of gestation and declined thereafter to the relatively low level found in adult brain. Immunoblot analyses with AbP2 as well as ligand-activated receptor autophosphorylation revealed an additional protein of 97 kDa. This protein was phosphorylated in response to IGF-1 and was not directly recognized by AbP4 or AbP5. The covalent association of the 97-kDa protein with the 92-kDa beta subunit was indicated by the ability of AbP4 and AbP5 to immunoprecipitate both proteins under nonreducing conditions but only the 92-kDa protein after reduction. In contrast, AbP2 immunoprecipitated both proteins regardless of their association. This immunospecificity remained unchanged after deglycosylation of the isolated proteins. Two-dimensional tryptic phosphopeptide analysis showed that the 92- and 97-kDa subunits of the IGF-1 receptor are related but distinct proteins. Taken together, the data suggest that the 92- and 97-kDa subunits differ in primary amino acid sequence. Thus, two distinct beta subunits may be present in a single IGF-1 receptor in brain. These subunits have in common an epitope recognized by an antibody to the tyrosine kinase domain (AbP2) but differ in regions thought to be important in receptor kinase regulation and signal transduction.
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17
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Lowe WL, Adamo M, Werner H, Roberts CT, LeRoith D. Regulation by fasting of rat insulin-like growth factor I and its receptor. Effects on gene expression and binding. J Clin Invest 1989; 84:619-26. [PMID: 2547834 PMCID: PMC548924 DOI: 10.1172/jci114207] [Citation(s) in RCA: 150] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We have examined, in liver and extrahepatic tissues, the effects of fasting on total insulin-like growth factor I (IGF-I) mRNA levels, on levels of different IGF-I mRNAs generated by alternative splicing of the primary IGF-I transcript, and on IGF-I receptor binding and mRNA levels. A 48-h fast decreased total IGF-I mRNA levels by approximately 80% in lung and liver, approximately 60% in kidney and muscle, and only approximately 30-40% in stomach, brain, and testes. In heart, IGF-I mRNA levels did not change. The levels of the different splicing variants, however, were essentially coordinately regulated within a given tissue. Specific 125I-IGF-I binding in lung, testes, stomach, kidney, and heart was increased by fasting by approximately 30-100%, whereas in brain 125I-IGF-I binding did not change in response to fasting. In tissues in which fasting increased IGF-I receptor number, receptor mRNA levels increased approximately 1.6- to 2.5-fold, whereas when IGF-I receptor number was unchanged in response to fasting, receptor mRNA levels did not change. These data demonstrate that the change in IGF-I and IGF-I receptor mRNA levels during fasting is quantitatively different in different tissues and suggest that regulation of IGF-I and IGF-I receptor gene expression by fasting is discoordinate.
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Affiliation(s)
- W L Lowe
- Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892
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18
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Garofalo RS, Rosen OM. Insulin and insulinlike growth factor 1 (IGF-1) receptors during central nervous system development: expression of two immunologically distinct IGF-1 receptor beta subunits. Mol Cell Biol 1989; 9:2806-17. [PMID: 2476658 PMCID: PMC362746 DOI: 10.1128/mcb.9.7.2806-2817.1989] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Insulin and insulinlike growth factor 1 (IGF-1) receptors are present in brain, yet their function remains obscure. Expression of these tyrosine kinase-bearing growth factor receptors during rat brain development was examined by using three antipeptide antibodies directed against epitopes in the beta subunits (AbP2, AbP4, and AbP5). All three antibodies recognized both insulin and IGF-1 receptors. Membranes were prepared from fetal brains (14 to 21 days of gestation), neonatal brain (postnatal day 1), and adult brain. Immunoblot analyses using AbP4 and AbP5 revealed a 92-kilodalton (kDa) protein that corresponded to the beta subunit of the insulin and IGF-1 receptors. Densitometric scanning of immunoblots indicated that receptor proteins were 4- to 10-fold more abundant in fetal brain membranes than in membranes from adult brain. Expression was highest during 16 to 18 days of gestation and declined thereafter to the relatively low level found in adult brain. Immunoblot analyses with AbP2 as well as ligand-activated receptor autophosphorylation revealed an additional protein of 97 kDa. This protein was phosphorylated in response to IGF-1 and was not directly recognized by AbP4 or AbP5. The covalent association of the 97-kDa protein with the 92-kDa beta subunit was indicated by the ability of AbP4 and AbP5 to immunoprecipitate both proteins under nonreducing conditions but only the 92-kDa protein after reduction. In contrast, AbP2 immunoprecipitated both proteins regardless of their association. This immunospecificity remained unchanged after deglycosylation of the isolated proteins. Two-dimensional tryptic phosphopeptide analysis showed that the 92- and 97-kDa subunits of the IGF-1 receptor are related but distinct proteins. Taken together, the data suggest that the 92- and 97-kDa subunits differ in primary amino acid sequence. Thus, two distinct beta subunits may be present in a single IGF-1 receptor in brain. These subunits have in common an epitope recognized by an antibody to the tyrosine kinase domain (AbP2) but differ in regions thought to be important in receptor kinase regulation and signal transduction.
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Affiliation(s)
- R S Garofalo
- Program in Molecular Biology, Memorial Sloan-Kettering Cancer Research Center, New York, New York
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19
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Adamo M, Raizada MK, LeRoith D. Insulin and insulin-like growth factor receptors in the nervous system. Mol Neurobiol 1989; 3:71-100. [PMID: 2553069 DOI: 10.1007/bf02935589] [Citation(s) in RCA: 166] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Insulin and the insulin-like growth factors (I and II) are homologous peptides essential to normal metabolism as well as growth. These peptide hormones are present in the brain, and, based on biosynthetic labeling studies as well as evidence for local gene expression, they are synthesized by nervous tissue as well as being taken up by the brain from the peripheral circulation. Furthermore, the presence of insulin and IGF receptors in the brain, on both neuronal and glial cells, also suggests a role for these peptides in the nervous system. Thus, these ligands affect brain electrical activity, either as neurotransmitters or as neuromodulators, altering the release and re-uptake of other neurotransmitters. The insulin and IGF-I and -II receptors found in the brain exhibit a lower molecular weight than corresponding receptors on peripheral tissues, primarily caused by alterations in glycosylation. Despite these alterations, both brain insulin and IGF-I receptors exhibit tyrosine kinase activity in cell-free systems, as do their peripheral counterparts. Brain insulin and IGF-I receptors are developmentally regulated, with the highest levels appearing in fetal or perinatal life. However, the altered glycosylation of brain receptors does not appear until late in fetal development. The receptors are widely distributed in the brain, but especially enriched in the circumventricular organs, choroid plexus, hypothalamus, cerebellum, and olfactory bulb. These studies on the insulin and IGF receptor in brain, add strong support to the suggestion that insulin and IGFs are important neuroactive substances, regulating growth, development, and metabolism in the brain.
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Affiliation(s)
- M Adamo
- Section of Molecular and Cellular Physiology, NIDDK, Bethesda, MD 20892
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20
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Montiel F, Ortiz-Caro J, Villa A, Pascual A, Aranda A. Presence of insulin receptors in cultured glial C6 cells. Regulation by butyrate. Biochem J 1989; 258:147-55. [PMID: 2930502 PMCID: PMC1138334 DOI: 10.1042/bj2580147] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The presence of insulin receptor and its regulation by butyrate and other short-chain fatty acids was studied in C6 cells, a rat glioma cell line. Intact C6 cells bind 125I-insulin in a rapid, reversible and specific manner. Scatchard analysis of the binding data gives typical curvilinear plots with apparent affinities of approx. 6 nM and 70 nM for the low-affinity (approx. 90% of total) and high-affinity (approx. 10% of total) sites respectively. Incubation with butyrate results in a time- and dose-dependent decrease of insulin binding to C6 cells. A maximal effect was found with 2 mM-butyrate that decreased the receptor by 40-70% after 48 h. Butyrate decreased numbers of receptors of both classes, but did not significantly alter receptor affinity. Other short-chain fatty acids, as well as keto acids, had a similar effect, but with a lower potency. Cycloheximide caused an accumulation of insulin receptors at the cell surface, since insulin binding increased and receptor affinity did not change after incubation with the inhibitor. Simultaneous addition of butyrate and cycloheximide abolished the loss of receptors produced by the fatty acid. In cells preincubated with butyrate, cycloheximide also produced a large increase in receptor numbers, showing that in the absence of new receptor synthesis a large pool of receptors re-appears at the surface of butyrate-treated cells.
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Affiliation(s)
- F Montiel
- Unidad de Endocrinologia Experimental, Instituto de Investigaciones Biomedicas, C.S.I.C., Madrid, Spain
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21
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Voll CL, Auer RN. The effect of postischemic blood glucose levels on ischemic brain damage in the rat. Ann Neurol 1988; 24:638-46. [PMID: 3059989 DOI: 10.1002/ana.410240508] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effect of insulin-induced hypoglycemia following 10.5 minutes of forebrain ischemia was studied in the rat. All groups received preischemic glucose loading (2 gm/kg) to promote brain infarction. Following completion of ischemia, rats received either 2 to 3 IU/kg (low-dose group) or 8 to 20 IU/kg (high-dose group) insulin. During the survival period, blood glucose concentrations were maintained in the ranges of 1.2 to 2.9 mM and 2.9 to 4.9 mM, respectively, for the low-dose and high-dose insulin groups. Control rats were given 2 gm/kg glucose immediately following ischemia. During the recovery period, until perfusion at 7 days, they were given glucose, 2 gm/kg, twice daily by intraperitoneal injection, and their drinking water was supplemented with 25% glucose. Mortality (p less than 0.05) and postischemic seizure incidence (p less than 0.01) were significantly reduced in the low-dose insulin group compared to the control group. Mortality was increased in the high-dose insulin group compared to the control group and was associated with an increased incidence of postischemic seizures. Neuropathological examination revealed no cortical infarction in the low-dose or high-dose insulin-treated rats compared to a 60% incidence of cortical infarction in the control group. In addition, the high-dose insulin-treated group showed a significant reduction in striatal and hippocampal CA1 selective neuronal necrosis compared to control rats with comparable survivals (p less than 0.05). The findings suggest that postischemic blood glucose concentrations play an important role in modulating both ischemic infarction and selective neuronal necrosis.
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Affiliation(s)
- C L Voll
- Department of Pathology, University of Calgary, Alberta, Canada
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22
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Piva R, Bianchini E, Kumar VL, Chambon P, del Senno L. Estrogen induced increase of estrogen receptor RNA in human breast cancer cells. Biochem Biophys Res Commun 1988; 155:943-9. [PMID: 2458728 DOI: 10.1016/s0006-291x(88)80587-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Estrogen Receptor (ER) RNA has been studied in ER positive and ER negative cells, grown in alpha medium and fetal calf serum (FCS), with and without estrogen addition. ER mRNA was detected only in ER positive cells. When cells were grown without estrogen addition, a progressive and transient increase of ER RNA levels was observed. When cells were cultured with estradiol, the ER RNA increase took place early and ER RNA levels remained 2 times higher than in untreated cells. Therefore, a down-regulation of ER RNA is not apparent in neoplastic breast cells. We hypothesize that the increase of ER expression is caused by stabilization of ER transcripts, due to the estrogen induced ER cytoplasmic depletion.
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Affiliation(s)
- R Piva
- Istituto di Chimica Biologica, Università di Ferrara, Italy
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23
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Recio-Pinto E, Ishii DN. Insulin and insulinlike growth factor receptors regulating neurite formation in cultured human neuroblastoma cells. J Neurosci Res 1988; 19:312-20. [PMID: 3288762 DOI: 10.1002/jnr.490190306] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The functional role of brain insulin and insulinlike growth factor (IGF) receptors is being sought. Recently it has been found that these ligands are members of a newly identified family of neuritogenic polypeptides. We studied the relationship between 125I-insulin and 125I-IGF binding and their capacity to enhance neurite formation in cultured human neuroblastoma SH-SY5Y cells. The binding of 125I-insulin was temperature-dependent and heterogeneous. The Scatchard plot and dissociation rate were both consistent with the presence of two types of sites. There appeared to be about 900 high affinity sites per cell with a Kd of about 3 nM. This compared favorably with the half-maximal concentration of 4 nM for enhancement of neurite formation. The type I IGF sites were also present. Physiologic concentrations of insulin clearly enhanced neurite formation through the insulin sites, whereas physiologic concentrations of IGF-I and IGF-II enhanced through the IGF sites. Cross-occupancy of sites was observed at supraphysiologic concentrations, providing a reasonable explanation for the broad dose-response curves for these ligands. These results support the suggestion that one function of insulin and IGF receptors in neural tissues may be to modulate neurite formation.
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Affiliation(s)
- E Recio-Pinto
- Department of Anesthesiology, Medical College, Cornell University, New York, New York
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24
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Kum W, Cockram CS, Zhu SQ, Teoh R, Vallance-Owen J, Young JD. Insulin binding and effects on pyrimidine nucleoside uptake and incorporation in cultured mouse astrocytes. J Neurochem 1987; 49:1293-300. [PMID: 3305789 DOI: 10.1111/j.1471-4159.1987.tb10023.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Binding of 125I-insulin to primary cultures of differentiated mouse astrocytes was time-dependent, reaching equilibrium after 2 h at 22 degrees C, with equilibrium binding corresponding to 20.79 fmol/mg of protein, representing approximately 5,000 occupied binding sites/cell. The half-life of 125I-insulin dissociation at 22 degrees C was 2 min, with an initial dissociation rate constant of 4.12 X 10(-2) s-1. Dissociation of bound 125I-insulin was not accelerated significantly in the presence of unlabeled insulin (16.7 microM). Porcine and desoctapeptide insulins competed for specific 125I-insulin binding in a dose-dependent manner, whereas growth hormone, glucagon, and somatostatin did not. For porcine insulin, Scatchard analysis suggested multiple-affinity binding sites (high-affinity Ka = 4.92 X 10(8) M-1; low-affinity Ka = 0.95 X 10(7) M-1). After incubation with insulin (0.5 microM) for 2 h at 37 degrees C, increases above basal values of 254 +/- 23 and 189 +/- 34% for [3H]uridine uptake and incorporation, respectively, were observed. After incubation with insulin (0.5 microM) for 24 h at 37 degrees C, there were increases of 145 +/- 6% for [3H]thymidine uptake and 166 +/- 11% for thymidine incorporation. Basal and stimulated uridine and thymidine uptake and incorporation were inhibited by 50 microM dipyridamole. These studies confirm that mouse astrocytes in vitro possess specific insulin receptors and demonstrate an effect of insulin on pyrimidine nucleoside uptake and incorporation.
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25
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Amino acid and putative neurotransmitter transport in human Y79 retinoblastoma cells. Effect of insulin and insulin-like growth factor. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)60915-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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26
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Fasting and refeeding alter the insulin receptor tyrosine kinase in chicken liver but fail to affect brain insulin receptors. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(19)76002-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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27
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Simon J, Leroith D. Insulin receptors of chicken liver and brain. Characterization of alpha and beta subunit properties. EUROPEAN JOURNAL OF BIOCHEMISTRY 1986; 158:125-32. [PMID: 3525156 DOI: 10.1111/j.1432-1033.1986.tb09729.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Receptors on membranes of chicken liver and brain bound porcine 125I-insulin in a specific and temperature-dependent manner. Competition with unlabeled insulin derivatives exhibited typical insulin potency ratios, i.e. chicken greater than porcine insulin greater than human proinsulin (2.1/1/0.02). Apparent binding affinity was higher in brain with a 50% inhibition of tracer binding of 1.3 +/- 0.2 nM porcine insulin as compared to 2.8 +/- 0.3 nM in liver. The apparent molecular mass of the 125I-insulin cross-linked alpha subunit of the insulin receptor was 139 +/- 2 kDa for chicken liver and 127 +/- 2 kDa for chicken brain. These molecular masses were similar to those of rat liver and brain insulin receptors. Neuraminidase treatment of the cross-linked insulin receptor increased the mobility of the alpha subunit from liver but did not affect that from brain, suggesting a difference in the glycosylation of the chicken brain alpha subunit as previously described in the rat. Despite this change, both receptors could be purified on wheat germ agglutinin (WGA) chromatography after Triton solubilization. In the presence of CTP and vanadate (phosphatase inhibitors) insulin-stimulatable tyrosine-specific phosphorylation of exogenous substrates was demonstrated with chicken liver and brain receptors. The reaction was dependent on Mg2+ and Mn2+. As noted with other insulin receptors, the best artificial substrate for phosphorylation was poly(Glu,Tyr)4:1. In both chicken liver and brain the smallest effective insulin dose as well as maximal stimulation of phosphorylation of the substrate was similar to that seen with rat liver, and in all three tissues chicken insulin was more potent than porcine insulin. In chicken liver an active ATP hydrolytic activity copurified with the insulin receptors during WGA chromatography. Further purification using S-300 Sephacryl filtration or affinity (insulin-biotin-avidin) chromatography could dissociate the phosphorylation and the hydrolytic activities. Gel electrophoresis, under reducing conditions revealed beta subunits with apparent Mr of 97-99 kDa in chicken liver and brain, which were phosphorylated in the presence of insulin. Similar apparent molecular masses have been described for the beta subunit of rat liver receptors. These studies suggest that both chicken brain and liver insulin receptors exhibit coupling of alpha and beta subunits with fully active tyrosine kinase and that the structural difference of the brain insulin receptor is widespread and phylogenetically old.
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28
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Roth RA, Morgan DO, Beaudoin J, Sara V. Purification and characterization of the human brain insulin receptor. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(17)35711-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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29
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Affolter V, Boujon P, Bestetti G, Rossi GL. Hypothalamic and cortical neurons of normotensive and spontaneously hypertensive rats are differently affected by streptozotocin diabetes. Acta Neuropathol 1986; 70:135-41. [PMID: 3739622 DOI: 10.1007/bf00691431] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Diabetic encephalopathy is a relatively frequent late complication in human and experimental diabetes mellitus. Although it is generally assumed that microangiopathy plays a major role in its pathogenesis, many aspects of the latter are still poorly understood. To detect possible correlations between vascular and cellular changes, we examined in normotensive and spontaneously hypertensive streptozotocin diabetic rats the neurons of hypothalamic and cortical regions in which the capillary basement membrane thickness had been known from a previous study. Arcuate and ventromedial nucleus neurons of normotensive diabetic rats compared to those of corresponding controls showed a reduced cytoplasmic area after 4 but not after 8 months of experiment. No difference was found between hypertensive control and diabetic rats after either 4 or 8 months of experiment. After the 8th month cortical neurons of normotensive controls were smaller in an occipital than in a frontal region and within the same region in the following layer order: deep less than superficial less than intermediate. Neurons of hypertensive controls behaved comparably yet were generally smaller than those of normotensive controls in each corresponding region. Compared to those of control, cortical neurons of normotensive diabetic rats were smaller in superficial and deep layers of both regions and in the intermediate layer of the frontal region. Hypertension appeared to antagonize diabetes. Despite an arcuate nucleus microangiopathy found in rats from both strains after 4 and 8 months of diabetes, neuronal changes were seen only in normotensive animals after 4 months. In the intermediate cortical layer, where microangiopathy was most marked after 8 months of experiment, neurons were not or only slightly reduced in size.(ABSTRACT TRUNCATED AT 250 WORDS)
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Abstract
Cultured human Y79 retinoblastoma cells bind [125I]iodoinsulin in a manner similar to that of other CNS and peripheral tissues. The only difference noted between the insulin binding properties of the Y79 cells and other CNS preparations is that insulin binding to Y79 cells is down-regulated by prolonged exposure of the cells to insulin. By contrast, studies with the various brain preparations indicate that the brain insulin receptor is not down-regulated by circulating levels of insulin. Insulin binding to Y79 cells exhibits negative cooperativity, has a pH optimum of 7.8, is responsive to cations, and gives a curvilinear Scatchard plot. Y79 cell insulin binding capacity is 26 fmol/100 micrograms of cell protein, corresponding to about 125,000 binding sites per cell. These findings are the first to report insulin binding in a human cell line of retinal origin. The characterization of the insulin binding in this cell line may facilitate an understanding of the relationship between insulin and its specific functions in the human retina.
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Clarke DW, Boyd FT, Kappy MS, Raizada MK. Insulin stimulates macromolecular synthesis in cultured glial cells from rat brain. THE AMERICAN JOURNAL OF PHYSIOLOGY 1985; 249:C484-9. [PMID: 2415002 DOI: 10.1152/ajpcell.1985.249.5.c484] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effect of insulin on macromolecular synthesis in glial cells cultured from brains of 1-day-old rats was studied to investigate the role of insulin in brain growth. Insulin caused a dose-dependent stimulation of protein synthesis (measured by [3H]valine incorporation into protein) that became significant by 7 nM insulin. Maximal stimulation of protein synthesis of 145% of control occurred with 18 nM insulin. Long-term protein synthesis was also stimulated to 136% of control by insulin in a dose-dependent manner after 6 days of insulin incubation. Insulin also stimulated net RNA and DNA synthesis (measured by [3H]uridine and [3H]thymidine incorporation into RNA or DNA, respectively) with significant stimulation by 2 nM insulin. Net RNA synthesis stimulation was maximal at 120% of control by 18 nM insulin. Plateau stimulation of DNA synthesis of 175% of control was reached by 200 nM insulin. The effects of insulin on glial protein and RNA synthesis appear to be mediated completely by the insulin receptor. Insulin, in physiological concentrations, stimulated glial DNA synthesis via its interaction with the insulin receptor (46% of total response). At supraphysiological concentrations insulin may have stimulated DNA synthesis via its cross-reactivity with the insulinlike growth factor I receptor (54% of total response). Thus insulin, at concentrations known to exist in the brain, stimulates the processes necessary for growth in the glial cell and is an important growth factor in the developing rat brain.
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Mill JF, Chao MV, Ishii DN. Insulin, insulin-like growth factor II, and nerve growth factor effects on tubulin mRNA levels and neurite formation. Proc Natl Acad Sci U S A 1985; 82:7126-30. [PMID: 3901011 PMCID: PMC391323 DOI: 10.1073/pnas.82.20.7126] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We have previously shown that insulin and the insulin-like growth factors share some important neurotrophic properties with nerve growth factor (NGF), including the capacity to enhance neurite formation. In this study, we have examined the effects of these neuritogenic agents on the expression of genes coding for important cytoskeletal proteins of axons and dendrites. Insulin specifically and coordinately increased the levels of alpha- and beta-tubulin mRNAs in human neuroblastoma SH-SY5Y cells. The dose-response curves for these increases were very similar to that for enhancement of neurite formation. Tubulin transcripts reached a transient maximum in approximately 1 day, suggesting that higher levels are important during initiation of neurites and that high levels are not required to sustain neurites once formed. Insulin-like growth factor II shared with insulin the capacity to substantially increase tubulin mRNA levels. NGF had but a small effect. Complementary mechanisms for these neurotrophic agents are suggested, because other studies show NGF and insulin can synergistically potentiate neurite formation. None of the factors altered the levels of actin mRNA. Thus, neurite formation does not seem to require a coordinate increase in actin and tubulin transcripts in SH-SY5Y cells.
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Abstract
We examined the structure of the affinity-labeled insulin receptors in rat brain, rat liver, and human IM-9 lymphocytes using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In gels run under reducing conditions, the alpha-subunit of the insulin receptor in brain had an apparent Mr of 127,000 distinctly lower than that seen in both rat liver and human lymphocytes (apparent Mr = 136,000). Exposure to neuraminidase increased the electrophoretic mobility of the liver receptor, but had no effect on the insulin receptor in brain. The carbohydrate moieties of the insulin receptors in rat brain and liver were further examined by chromatography on wheat-germ agglutinin agarose. The receptors in both tissues adsorbed to the wheat-germ agglutinin; elution with 0.3 M N-acetyl glucosamine resulted in slightly better recovery of the brain than of the liver receptor. Exposure to neuraminidase virtually abolished the interaction of the liver receptor with the lectin, whereas adsorption of the brain receptor was unaffected by neuraminidase. These results indicate that the insulin receptor in brain is distinguished from those in peripheral tissues by structural alterations, including changes in the carbohydrate moiety of the receptor. Such alterations contrast sharply with the previously observed similarities in insulin binding properties between insulin receptors in brain and other tissues. The implications of such structural alterations for the program of insulin action expressed by the receptors in brain remain to be explored.
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Van Schravendijk CF, Hooghe-Peters EL, De Meyts P, Pipeleers DG. Identification and characterization of insulin receptors on foetal-mouse brain-cortical cells. Biochem J 1984; 220:165-72. [PMID: 6378183 PMCID: PMC1153606 DOI: 10.1042/bj2200165] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The occurrence of insulin receptors was investigated in freshly dissociated brain-cortical cells from mouse embryos. By analogy with classical insulin-binding cell types, binding of 125I-insulin to foetal brain-cortical cells was time- and pH-dependent, only partially reversible, and competed for by unlabelled insulin and closely related peptides. Desalanine-desasparagine-insulin, pig proinsulin, hagfish insulin and turkey insulin were respectively 2%, 4%, 2% and 200% as potent as bovine insulin in inhibiting 125I-insulin binding to brain-cortical cells, which corresponds to their relative biological potencies in classical insulin-target cells; no competition was observed with glucagon and nerve growth factor, even at high concentrations. Scatchard analysis of competitive-binding data resulted in curvilinear plots with a high-affinity binding of Ka = 3.6 X 10(8) M-1. Insulin binding to foetal brain-cortical cells differed, however, in two distinct aspects from that to classical insulin-binding cell types. Firstly, dilution of 125I-insulin-bound cells in the presence of unlabelled insulin did not accelerate dissociation of the labelled hormone. Secondly, exposure of brain-cortical cells to insulin before the binding assay enhanced insulin binding, suggesting up-regulation of insulin receptors in response to insulin. In conclusion, foetal-mouse brain-cortical cells bear specific binding sites for insulin. Their insulin receptor shows a marked specificity and affinity for insulin, but differs in at least two properties from most classical insulin receptors. These differences in hormone-receptor interaction could reflect structural differences between insulin receptors on embryonic and differentiated cells.
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Zahniser NR, Goens MB, Hanaway PJ, Vinych JV. Characterization and regulation of insulin receptors in rat brain. J Neurochem 1984; 42:1354-62. [PMID: 6323631 DOI: 10.1111/j.1471-4159.1984.tb02795.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
An in vitro receptor binding assay, using filtration to separate bound from free [125I]insulin, was developed and used to characterize insulin receptors on membranes isolated from specific areas of rat brain. The kinetic and equilibrium binding properties of central receptors were similar to those of hepatic receptors. The binding profiles in all tissues were complex and were consistent with binding in multiple steps or to multiple sites. Similar binding properties were found among receptors in olfactory tubercle/bulb, cerebral cortex, hippocampus, striatum, hypothalamus, and cerebellum. High affinity [125I]insulin binding sites (KD = 3-11 nM) were distributed evenly between membranes isolated from P1 and P2 fractions of these brain areas, with the exception of the olfactory tubercle in which binding to P2 membranes was four-fold greater (Bmax = 150 fmol/mg protein). One difference between insulin receptors in brain and peripheral target tissues, however, was observed. Following exposure to 0.17 microM insulin for 3 h at 37 degrees C, the number of specific [125I]insulin binding sites on adipocytes decreased by 40%, while the number of binding sites on minces of cerebral cortex/olfactory tubercle remained constant. The results suggest that although the binding characteristics of central and peripheral insulin receptors are similar, these receptors do not appear to be regulated in the same manner.
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Abstract
Insulin (2U-regular) was administered intracerebrally or intraperitoneally in newborn rabbit pups, to study the effect of the hormone on brain insulin receptor characteristics. Intraperitoneal insulin treatment produced an increase in plasma insulin concentrations from a control of approximately 24 microU/ml to 132 +/- 36 (p less than 0.02) and a decrease in plasma glucose from approximately 83 to 27 +/- 10 mg/dl (p less than 0.01). No change in brain insulin receptor characteristics was observed. On the other hand, insulin injected intracerebrally raised the plasma insulin to greater than 3000 microU/ml and lowered the plasma glucose to 32 +/- 8 mg/dl (p less than .05). In addition a decrease in brain insulin receptor sites from 262 +/- 9 X 10(10) mg protein-1 to 159 +/- 6 (p less than 0.001) was noted. When the data was expressed per microgram DNA, a decrease from 4 +/- 0.4 X 10(10) to 2.5 +/- 0.2 (p less than .01) in receptor sites resulted. No change in the receptor affinity was observed. We conclude that a direct exposure of the brain to excess insulin results in a down-regulation of the brain insulin receptors.
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Rhoads DE, DiRocco RJ, Osburn LD, Peterson NA, Raghupathy E. Stimulation of synaptosomal uptake of neurotransmitter amino acids by insulin: possible role of insulin as a neuromodulator. Biochem Biophys Res Commun 1984; 119:1198-204. [PMID: 6143558 DOI: 10.1016/0006-291x(84)90903-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Insulin stimulates in a dose-dependent manner (concentration range of 0.1 - 10 microM) the synaptosomal uptake of amino acids characterized by high-affinity, Na+-dependent, veratridine-sensitive transport systems. This stimulation is observed in synaptosomes prepared from each of several regions of the adult rat brain. Both the initial rate of amino acid uptake and the overall capacity for amino acid accumulation are increased. Since these transport systems have been associated with the neurotransmitter role of the amino acids, we postulate that insulin can modulate neurotransmission in the rat central nervous system by increasing the efficiency of neuroactive amino acid reuptake.
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Rees-Jones RW, Hendricks SA, Quarum M, Roth J. The insulin receptor of rat brain is coupled to tyrosine kinase activity. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43117-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Villa-Komaroff L, Gonzalez A, Song HY, Wentworth B, Dobner P. Novel insulin-related sequences in fetal brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1984; 181:65-86. [PMID: 6397976 DOI: 10.1007/978-1-4684-4868-9_7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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40
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Abstract
Specific insulin binding has been demonstrated in partially purified membranes prepared from four regions of the developing rat brain. Insulin binding to brain membranes demonstrated kinetics and hormonal specificity that were quite similar to those reported for traditional insulin target tissues (e.g., liver and adipose tissue), and binding was significantly correlated with receptor concentration. Binding in the olfactory bulbs, cerebrum, cerebellum, and hypothalamus all reached highest values at 15 days of postnatal life, with the olfactory bulbs generally showing the greatest binding at all ages studied. A temporal relationship was found between insulin binding to brain membranes in the postnatal rat and plasma membrane protein synthesis, especially in the cerebellum and olfactory bulbs.
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41
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Heidenreich KA, Zahniser NR, Berhanu P, Brandenburg D, Olefsky JM. Structural differences between insulin receptors in the brain and peripheral target tissues. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32085-4] [Citation(s) in RCA: 104] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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42
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Weyhenmeyer JA, Fellows RE. Presence of immunoreactive insulin in neurons cultured from fetal rat brain. Cell Mol Neurobiol 1983; 3:81-6. [PMID: 6136329 DOI: 10.1007/bf00735000] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Immunocytochemical studies have been performed which establish the presence of immunoreactive (ir-) insulin in primary cultures from fetal rat brain. Approximately 1% of the identified neurons in culture contained insulin immunoreactivity. Typically, a diffuse staining pattern was observed in the perikaryia and fiber profiles of peroxidase-anti-peroxidase-positive neurons. Varicosity-like structures containing ir-insulin were found on the majority of positively stained fiber profiles. A small number of the neurons appeared to have cytoplasmic granules that stained densely for insulin. No significant staining was observed in the background monolayer of cells predominantly of glial origin. The substitution of primary antiserum absorbed with excess insulin or preimmune serum eliminated staining in the neurons. The observation of insulin immunoreactivity in neurons suggests that insulin may be a neuromodulator in the central nervous system.
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Raizada MK. Localization of insulin-like immunoreactivity in the neurons from primary cultures of rat brain. Exp Cell Res 1983; 143:351-7. [PMID: 6339256 DOI: 10.1016/0014-4827(83)90061-7] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Brains from 1-day-old rats were dissociated with trypsin and the cells were maintained in culture for 3-4 weeks. These primary cultures contained insulin-like immunoreactivity in the limited populations of neurons. Typically, the fluorescent staining pattern observed in the soma was homogeneous and varicosity-like structures were observed on the neurites of the majority of insulin-like immunoreactive neurons. Serum deprivation of brain cell cultures did not reduce immunoreactivity, whereas cycloheximide caused approx. 80% decrease in the number of insulin-like immunoreactive neurons. Incubation of these cultures with [3H]valine resulted in the incorporation of radioactivity into immunoprecipitable insulin. These results suggest that insulin-like immunoreactivity present in the Central Nervous System (CNS) neurons may be synthesized by brain cell cultures.
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Woods SC, Porte D. The role of insulin as a satiety factor in the central nervous system. ADVANCES IN METABOLIC DISORDERS 1983; 10:457-68. [PMID: 6364721 DOI: 10.1016/b978-0-12-027310-2.50024-4] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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46
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47
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Saito A, Williams JA, Waxler SH, Goldfine ID. Alterations of brain cholecystokinin receptors in mice made obese with goldthioglucose. J Neurochem 1982; 39:525-8. [PMID: 6283026 DOI: 10.1111/j.1471-4159.1982.tb03976.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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48
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Wyse BM, Chang AY. Insulin binding in cultured Chinese hamster kidney epithelial cells: the effect of serum in the medium. IN VITRO 1982; 18:243-50. [PMID: 6752000 DOI: 10.1007/bf02618577] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
[125I] Insulin (porcine) binding to an epithelial cell line established from a Chinese hamster kidney, CHK-AC E-100, showed an optimum at pH 8.0 and reached a maximum after 2.5 h incubation at 25 degrees C. Dissociation of bound [125I] insulin was facilitated by the addition of unlabeled insulin in the dilution buffer. Porcine insulin effectively competed for [125I] insulin binding to the cultured cells and was 30 and 90 times as potent as guinea pig insulin and porcine proinsulin in causing 50% inhibition of [125I] insulin binding; glucagon was completely ineffective. Scatchard analysis of the binding data yielded a curvilinear plot and a capacity of 0.6 ng/10(6) cells; the average affinity of the empty receptor, Ke, was calculated to be 1.78 X 10(6) M-1 and that of the filled receptor, Kf, 0.57 X 10(8) m-1, Substitution of fetal bovine serum (FBS) in the culture medium with bovine calf, bovine newborn, of bovine calf serum altered insulin binding characteristics in the cells and reduced cell growth. Insulin binding characteristics of cells grown in hormone-supplemented medium containing 0 to 0.1% FBS were similar to those of cells grown in minimum essential medium (MEM) containing 2 to 5% FBS. The data indicated that the established Chinese hamster kidney epithelial cell line CHK-AC E-100 possessed specific insulin receptors and the characteristics of the receptors could be manipulated by changing the serum in culture medium.
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Raizada MK, Stamler JF, Quinlan JT, Landas S, Phillips MI. Identification of insulin receptor-containing cells in primary cultures of rat brain. Cell Mol Neurobiol 1982. [DOI: 10.1007/bf00735066] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Morrison RS, de Vellis J. Growth of purified astrocytes in a chemically defined medium. Proc Natl Acad Sci U S A 1981; 78:7205-9. [PMID: 6458820 PMCID: PMC349225 DOI: 10.1073/pnas.78.11.7205] [Citation(s) in RCA: 182] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Astrocytes purified from primary cultures of neonatal rat cerebrum can now be grown in a synthetic medium supplemented with putrescine, prostaglandin F2 alpha, insulin, fibroblast growth factor, and hydrocortisone. These five supplements have a marked synergistic effect on growth when used in combination but have little effect when used individually. Astrocytes grown in the defined medium exhibit dramatic changes in morphological characteristics in comparison to cells grown in serum-free or serum-supplemented medium. In addition, these cells express the astrocyte-specific marker glial fibrillary acidic protein and are estimated by several criteria to be greater than 95% astrocytes.
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