1
|
Lebda MA, Sadek KM, El-Sayed YS. Aspartame and Soft Drink-Mediated Neurotoxicity in Rats: Implication of Oxidative Stress, Apoptotic Signaling Pathways, Electrolytes and Hormonal Levels. Metab Brain Dis 2017; 32:1639-1647. [PMID: 28660358 DOI: 10.1007/s11011-017-0052-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 06/16/2017] [Indexed: 01/06/2023]
Abstract
A significant association between fructose corn syrup in sweetened beverages consumption and increased risk of detrimental central nervous system effects has been recently reported. We hypothesized that the aspartame and soft drink induced disturbances in energy production and endocrine function, which play a role in the induction of brain damage. Therefore, we aimed to assess the effect of aspartame and soft drink on brain function and the link between energy status in the brain, oxidative stress and molecular pathways of apoptosis. Thirty rats were randomly assigned to drink water, aspartame (240 mg/kg orally) and cola soft drinks (free access) daily for two months. Subchronic intake of aspartame and soft drink significantly disrupted the brain energy production, as indicated by inhibited serum and brain creatine kinase, specifically in soft drink-received rats. Moreover, they substantially altered serum electrolytes (increased Ca and Na, and depleted Cu, Fe, Zn and K levels), and accordingly the related hormonal status (increased T4 and PTH, and lowered T3 and aldosterone levels), particularly in soft drink-received rats reflecting brain damage. Additionally, significant increment of acetylcholine esterase activity concomitant with the reduction of antioxidant molecules (SOD, CAT, GSH-Px and GSH), and induction of malondialdehyde level are precisely indicative of oxidative brain damage. Brain mRNA transcripts of target genes showed that aspartame and soft drink induced upregulation of BAX, Casp3, P27 and Mdm2 (1.5-fold) and down-regulation of Bcl2, suggesting an activation of cellular apoptosis. Collectively, subchronic aspartame and soft drink-induced brain damage in rats may be driven via a mechanism that involves energy production disruption, electrolytes and hormonal imbalance, increased oxidative stress and activation of molecular pathway of neuronal apoptosis.
Collapse
Affiliation(s)
- Mohamed A Lebda
- Department of Biochemistry, Faculty of Veterinary Medicine, Alexandria University, Edfina, 22758, Egypt
| | - Kadry M Sadek
- Department of Biochemistry, Faculty of Veterinary Medicine, Damanhour University, Damanhour, 22511, Egypt
| | - Yasser S El-Sayed
- Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, Damanhour University, Damanhour, 22511, Egypt.
| |
Collapse
|
2
|
Lam V, Takechi R, Pallabage-Gamarallage M, Giles C, Mamo JCL. The vitamin D, ionised calcium and parathyroid hormone axis of cerebral capillary function: therapeutic considerations for vascular-based neurodegenerative disorders. PLoS One 2015; 10:e0125504. [PMID: 25874538 PMCID: PMC4395380 DOI: 10.1371/journal.pone.0125504] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 03/19/2015] [Indexed: 12/23/2022] Open
Abstract
Blood-brain barrier dysfunction characterised by brain parenchymal extravasation of plasma proteins may contribute to risk of neurodegenerative disorders, however the mechanisms for increased capillary permeability are not understood. Increasing evidence suggests vitamin D confers central nervous system benefits and there is increasing demand for vitamin D supplementation. Vitamin D may influence the CNS via modulation of capillary function, however such effects may be indirect as it has a central role in maintaining calcium homeostasis, in concert with calcium regulatory hormones. This study utilised an integrated approach and investigated the effects of vitamin D supplementation, parathyroid tissue ablation (PTX), or exogenous infusion of parathyroid hormone (PTH) on cerebral capillary integrity. Parenchymal extravasation of immunoglobulin G (IgG) was used as a marker of cerebral capillary permeability. In C57BL/6J mice and Sprague Dawley rats, dietary vitamin D was associated with exaggerated abundance of IgG within cerebral cortex (CTX) and hippocampal formation (HPF). Vitamin D was also associated with increased plasma ionised calcium (iCa) and decreased PTH. A response to dose was suggested and parenchymal effects persisted for up to 24 weeks. Ablation of parathyroid glands increased CTX- and HPF-IgG abundance concomitant with a reduction in plasma iCa. With the provision of PTH, iCa levels increased, however the PTH treated animals did not show increased cerebral permeability. Vitamin D supplemented groups and rats with PTH-tissue ablation showed modestly increased parenchymal abundance of glial-fibrillary acidic protein (GFAP), a marker of astroglial activation. PTH infusion attenuated GFAP abundance. The findings suggest that vitamin D can compromise capillary integrity via a mechanism that is independent of calcium homeostasis. The effects of exogenous vitamin D supplementation on capillary function and in the context of prevention of vascular neurodegenerative conditions should be considered in the context of synergistic effects with calcium modulating hormones.
Collapse
Affiliation(s)
- Virginie Lam
- School of Public Health, Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia
- Curtin Health Innovation Research Institute of Ageing and Chronic Disease, Curtin University, Perth, Western Australia, Australia
| | - Ryusuke Takechi
- School of Public Health, Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia
- Curtin Health Innovation Research Institute of Ageing and Chronic Disease, Curtin University, Perth, Western Australia, Australia
| | - Menuka Pallabage-Gamarallage
- School of Public Health, Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia
- Curtin Health Innovation Research Institute of Ageing and Chronic Disease, Curtin University, Perth, Western Australia, Australia
| | - Corey Giles
- School of Public Health, Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia
- Curtin Health Innovation Research Institute of Ageing and Chronic Disease, Curtin University, Perth, Western Australia, Australia
| | - John C. L. Mamo
- School of Public Health, Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia
- Curtin Health Innovation Research Institute of Ageing and Chronic Disease, Curtin University, Perth, Western Australia, Australia
- * E-mail:
| |
Collapse
|
3
|
Nghia NA, Hirasawa T, Kasai H, Obata C, Moriishi K, Mochizuki K, Koizumi S, Kubota T. Long-term imipramine treatment increases N-methyl-d-aspartate receptor activity and expression via epigenetic mechanisms. Eur J Pharmacol 2015; 752:69-77. [PMID: 25701723 DOI: 10.1016/j.ejphar.2015.02.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 02/03/2015] [Accepted: 02/10/2015] [Indexed: 01/10/2023]
Abstract
Imipramine, a major antidepressant, is known to inhibit reuptake of serotonin and norepinephrine, which contributes to recovery from major depressive disorder. It has recently been reported that acute imipramine treatment inhibits N-methyl-d-aspartate (NMDA) receptor activity. However, the mechanisms underlying long-term effects of imipramine have not been identified. We tested these distinct effects in mouse cortical neurons and found that acute (30s) imipramine treatment decreased Ca(2+) influx through NMDA receptors, whereas long-term treatment (48h) increased Ca(2+) influx via the same receptors. Furthermore, long-term treatment increased NMDA receptor 2B (NR2B) subunit expression via epigenetic changes, including increased acetylation of histones H3K9 and H3K27 in the NR2B promoter and decreased activity of histone deacetylase 3 (HDAC3) and HDAC4. These results suggest that the long-term effects of imipramine on NMDA receptors are quite different from its acute effects. Furthermore, increased NR2B expression via epigenetic alterations might be a part of the mechanism responsible for this long-term effect.
Collapse
Affiliation(s)
- Nguyen An Nghia
- Department of Epigenetic Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| | - Takae Hirasawa
- Department of Epigenetic Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan; Japan Science and Technology Agency (JST), CREST, 4-1-8 Honcho, Kawaguchi, Saitama, Japan.
| | - Hirotake Kasai
- Department of Microbiology, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| | - Chie Obata
- Department of Epigenetic Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan; Japan Science and Technology Agency (JST), CREST, 4-1-8 Honcho, Kawaguchi, Saitama, Japan
| | - Kohji Moriishi
- Department of Microbiology, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| | - Kazuki Mochizuki
- Faculty of Life and Environmental Sciences, University of Yamanashi, Takeda, Kofu, Yamanashi 409-8510, Japan
| | - Schuichi Koizumi
- Department of Pharmacology, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| | - Takeo Kubota
- Department of Epigenetic Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| |
Collapse
|
4
|
Annweiler C, Montero-Odasso M, Schott AM, Berrut G, Fantino B, Beauchet O. Fall prevention and vitamin D in the elderly: an overview of the key role of the non-bone effects. J Neuroeng Rehabil 2010; 7:50. [PMID: 20937091 PMCID: PMC2959005 DOI: 10.1186/1743-0003-7-50] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Accepted: 10/11/2010] [Indexed: 11/29/2022] Open
Abstract
Preventing falls and fall-related fractures in the elderly is an objective yet to be reached. There is increasing evidence that a supplementation of vitamin D and/or of calcium may reduce the fall and fracture rates. A vitamin D-calcium supplement appears to have a high potential due to its simple application and its low cost. However, published studies have shown conflicting results as some studies failed to show any effect, while others reported a significant decrease of falls and fractures. Through a 15-year literature overview, and after a brief reminder on mechanism of falls in older adults, we reported evidences for a vitamin D action on postural adaptations - i.e., muscles and central nervous system - which may explain the decreased fall and bone fracture rates and we underlined the reasons for differences and controversies between published data. Vitamin D supplementation should thus be integrated into primary and secondary fall prevention strategies in older adults.
Collapse
Affiliation(s)
- Cedric Annweiler
- Department of Internal Medicine and Geriatrics, Angers University Hospital; Angers University Memory Center; UPRES EA 2646, University of Angers, UNAM, Angers, France
| | - Manuel Montero-Odasso
- Department of Medicine, Division of Geriatric Medicine, University of Western Ontario, London, Ontario, Canada
| | - Anne M Schott
- Department IMER, Lyon University Hospital; EA 4129, RECIF, University of Lyon; Inserm, U831, Lyon, France
| | - Gilles Berrut
- Department of Geriatrics, Nantes University Hospital; University of Nantes, UNAM, Nantes, France
| | - Bruno Fantino
- Department of Internal Medicine and Geriatrics, Angers University Hospital; Angers University Memory Center; UPRES EA 2646, University of Angers, UNAM, Angers, France
| | - Olivier Beauchet
- Department of Internal Medicine and Geriatrics, Angers University Hospital; Angers University Memory Center; UPRES EA 2646, University of Angers, UNAM, Angers, France
| |
Collapse
|
5
|
Lundy FT, About I, Curtis TM, McGahon MK, Linden GJ, Irwin CR, El Karim IA. PAR-2 regulates dental pulp inflammation associated with caries. J Dent Res 2010; 89:684-8. [PMID: 20505052 DOI: 10.1177/0022034510365652] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Protease-activated receptors (PARs) are G-protein-coupled receptors that are activated enzymatically by proteolysis of an N-terminal domain. The cleavage and activation of PARs by serine proteases represent a novel mechanism by which such enzymes could influence the host inflammatory response. The aim of this study was to determine whether PAR-2 expression and activation were increased in dental caries. Using immunohistochemistry, we showed PAR-2 to be localized to pulp cells subjacent to caries lesions, but minimally expressed by healthy pulp tissue. Trypsin and the PAR-2 agonist (PAR2-AP) activated PAR-2 in an in vitro functional assay. Endogenous molecules present in pulp cell lysates from carious teeth specifically activated PAR-2, but those from healthy teeth failed to do so. The activation of PAR-2 in vitro was shown to increase the expression of the pro-inflammatory mediator cyclo-oxygenase-2 (COX-2), providing a mechanism whereby PAR-2 could modulate pulpal inflammation.
Collapse
Affiliation(s)
- F T Lundy
- Centre for Infection and Immunity, School of Medicine, Dentistry and Biomedical Sciences, Whitla Medical Building, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, United Kingdom.
| | | | | | | | | | | | | |
Collapse
|
6
|
Does elevated parathyroid hormone concentration predict cognitive decline in older people? Aging Clin Exp Res 2010; 22:164-9. [PMID: 19934619 DOI: 10.1007/bf03324791] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND AND AIMS Increased parathyroid activity has been associated with impaired cognitive function, although the predictive value of parathyroid hormone (PTH) for cognitive decline has not yet been fully investigated. This association was evaluated in random persons of age cohorts of 75, 80 and 85 years in a 10- year longitudinal prospective study. METHODS Cognition of patients (n=514) was assessed with the Mini-Mental State Examination (MMSE) and Clinical Dementia Rating (CDR) at baseline and at intervals of one, five and ten years. Clinical data were collected and serum PTH, ionized calcium (Ca2+) and creatinine as well as apolipoprotein E (APOE) alleles were determined at baseline. RESULTS Impaired cognition (MMSE<24 or CDR> or =1) was associated with older age, impaired renal function, and elevated PTH (> or =62 ng/L, IV-quartile) at baseline. Elevated PTH indicated a 2-fold risk of an at least 4-point decrease in MMSE (OR 2.20) and a 3-fold risk of an increase in CDR-class (OR 3.20) within the first year of follow- up. The risk remained significantly elevated even after controlling for age, gender, baseline cognition, serum Ca2+, creatinine, and APOE4 (OR 2.24 for MMSE; OR 2.12 for CDR). High PTH also predicted cognitive decline within a five-year follow-up (OR 3.20), but the association disappeared at ten years. CONCLUSIONS Elevated PTH concentrations are associated with a five-year cognitive decline in a general aged population, independently of Ca2+ and renal function. The role of vitamin D deficiency, the most common cause of elevated PTH in the elderly, needs to be further investigated.
Collapse
|
7
|
Chapter MC, White CM, DeRidder A, Chadwick W, Martin B, Maudsley S. Chemical modification of class II G protein-coupled receptor ligands: frontiers in the development of peptide analogs as neuroendocrine pharmacological therapies. Pharmacol Ther 2009; 125:39-54. [PMID: 19686775 DOI: 10.1016/j.pharmthera.2009.07.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 07/24/2009] [Indexed: 01/08/2023]
Abstract
Recent research and clinical data have begun to demonstrate the huge potential therapeutic importance of ligands that modulate the activity of the secretin-like, Class II, G protein-coupled receptors (GPCRs). Ligands that can modulate the activity of these Class II GPCRs may have important clinical roles in the treatment of a wide variety of conditions such as osteoporosis, diabetes, amyotrophic lateral sclerosis and autism spectrum disorders. While these receptors present important new therapeutic targets, the large glycoprotein nature of their cognate ligands poses many problems with respect to therapeutic peptidergic drug design. These native peptides often exhibit poor bioavailability, metabolic instability, poor receptor selectivity and resultant low potencies in vivo. Recently, increased attention has been paid to the structural modification of these peptides to enhance their therapeutic efficacy. Successful modification strategies have included d-amino acid substitutions, selective truncation, and fatty acid acylation of the peptide. Through these and other processes, these novel peptide ligand analogs can demonstrate enhanced receptor subtype selectivity, directed signal transduction pathway activation, resistance to proteolytic degradation, and improved systemic bioavailability. In the future, it is likely, through additional modification strategies such as addition of circulation-stabilizing transferrin moieties, that the therapeutic pharmacopeia of drugs targeted towards Class II secretin-like receptors may rival that of the Class I rhodopsin-like receptors that currently provide the majority of clinically used GPCR-based therapeutics. Currently, Class II-based drugs include synthesized analogs of vasoactive intestinal peptide for type 2 diabetes or parathyroid hormone for osteoporosis.
Collapse
Affiliation(s)
- Megan C Chapter
- Receptor Pharmacology Unit, Laboratory of Neuroscience, National Institute on Aging, Biomedical Research Center, 251 Bayview Blvd., Baltimore MD 21224, USA
| | | | | | | | | | | |
Collapse
|
8
|
Morita M, Saruta C, Kozuka N, Okubo Y, Itakura M, Takahashi M, Kudo Y. Dual regulation of astrocyte gap junction hemichannels by growth factors and a pro-inflammatory cytokine via the mitogen-activated protein kinase cascade. Glia 2007; 55:508-15. [PMID: 17211868 DOI: 10.1002/glia.20471] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Evidence that glutamate and ATP release from astrocytes can occur via gap junction hemichannels (GJHCs) is accumulating. However, the GJHC is still only one possible release mechanism and has not been detected in some studies, although this may be because the levels were below those detectable by the system used. Because of these conflicting results, we hypothesized that release from astrocyte GJHCs might depend on different astrocyte states, and screened for factors affecting astrocyte GJHC activity by measuring fluorescent dye leakage via GJHCs using a conventional method for GJHC acivation, i.e. removal of extracellular divalent cations. Astrocytes cultured in Dulbecco's minimal essential medium containing 10% fetal calf serum, a medium widely used for astrocyte studies, did not show dye leakage, whereas those cultured in a defined medium showed substantial dye leakage, which was confirmed pharmacologically to be due to GJHCs and not to P2x7 receptors. EGF and bFGF inhibited the GJHC activity via the mitogen-activated protein kinase cascade, and the effect of the growth factors was reversed by interleukin-1beta. These factors altered GJHC activity within 10 min, but did not affect connexin 43 expression. GJHC activity in hippocampal slice culture preparations was measured using the same methods and found to be regulated in a similar manner. These results indicate that astrocyte GJHC activity is regulated by brain environmental factors.
Collapse
Affiliation(s)
- Mitsuhiro Morita
- Laboratory of Cellular Neurobiology, School of Life Science, Tokyo University of Pharmacy and Life Science, Tokyo, Japan.
| | | | | | | | | | | | | |
Collapse
|
9
|
Martin B, Lopez de Maturana R, Brenneman R, Walent T, Mattson MP, Maudsley S. Class II G protein-coupled receptors and their ligands in neuronal function and protection. Neuromolecular Med 2005; 7:3-36. [PMID: 16052036 PMCID: PMC2636744 DOI: 10.1385/nmm:7:1-2:003] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2005] [Accepted: 01/26/2005] [Indexed: 12/20/2022]
Abstract
G protein-coupled receptors (GPCRs) play pivotal roles in regulating the function and plasticity of neuronal circuits in the nervous system. Among the myriad of GPCRs expressed in neural cells, class II GPCRs which couples predominantly to the Gs-adenylate cyclase-cAMP signaling pathway, have recently received considerable attention for their involvement in regulating neuronal survival. Neuropeptides that activate class II GPCRs include secretin, glucagon-like peptides (GLP-1 and GLP-2), growth hormone-releasing hormone (GHRH), pituitary adenylate cyclase activating peptide (PACAP), corticotropin-releasing hormone (CRH), vasoactive intestinal peptide (VIP), parathyroid hormone (PTH), and calcitonin-related peptides. Studies of patients and animal and cell culture models, have revealed possible roles for class II GPCRs signaling in the pathogenesis of several prominent neurodegenerative conditions including stroke, Alzheimer's, Parkinson's, and Huntington's diseases. Many of the peptides that activate class II GPCRs promote neuron survival by increasing the resistance of the cells to oxidative, metabolic, and excitotoxic injury. A better understanding of the cellular and molecular mechanisms by which class II GPCRs signaling modulates neuronal survival and plasticity will likely lead to novel therapeutic interventions for neurodegenerative disorders.
Collapse
Affiliation(s)
- Bronwen Martin
- Laboratory of Neurosciences, National Institute on Ageing Intramural Research Program, Gerontology Research Center, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
| | | | | | | | | | | |
Collapse
|
10
|
Jorde R, Waterloo K, Saleh F, Haug E, Svartberg J. Neuropsychological function in relation to serum parathyroid hormone and serum 25-hydroxyvitamin D levels. The Tromsø study. J Neurol 2005; 253:464-70. [PMID: 16283099 DOI: 10.1007/s00415-005-0027-5] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2005] [Revised: 08/18/2005] [Accepted: 08/29/2005] [Indexed: 12/12/2022]
Abstract
There are receptors for parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D in the brain, and there are clinical and experimental data indicating that PTH and vitamin D may affect cerebral function. In the present study 21 subjects who both in the 5th Tromsø study and at a follow-up examination fulfilled criteria for secondary hyperparathyroidism (SHPT) without renal failure (serum calcium < 2.40 mmol/L, serum PTH > 6.4 pmol/L, and normal serum creatinine) and 63 control subjects were compared with tests for cognitive and emotional function. Those in the SHPT group had significantly impaired performance in 3 of 14 cognitive tests (Digit span forward, Stroop test part 1 and 2, and Word association test (FAS)) as compared with the controls, and also had a significantly higher depression score at the Beck Depression Inventory (BDI) (items 1-13). In a multiple linear regression model, a high serum PTH level was significantly associated with low performance at the Digit span forward, Stroop test part 1 and 2, and Digit Symbol tests. A low level of serum 25-hydroxyvitamin D was significantly associated with a high depression score. In conclusion, a deranged calcium metabolism appears to be associated with impaired function in several tests of neuropsychological function.
Collapse
Affiliation(s)
- Rolf Jorde
- Department of Internal Medicine, Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway.
| | | | | | | | | |
Collapse
|
11
|
Hirasawa T, Wada H, Kohsaka S, Uchino S. Inhibition of NMDA receptors induces delayed neuronal maturation and sustained proliferation of progenitor cells during neocortical development. J Neurosci Res 2004; 74:676-87. [PMID: 14635219 DOI: 10.1002/jnr.10795] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To elucidate the role of N-methyl-D-aspartate (NMDA) receptors during the early stage of cerebral neocortical development, we investigated the effect of an NMDA receptor antagonist, D(-)-2-amino-5-phosphonopentanoic acid (D-APV), on cell migration and proliferation in slice cultures and dissociated primary cultures prepared from rat cerebral neocortex at embryonic Day 17. Pulse-labeling experiments with 5-bromo-2'-deoxyuridine (BrdU) showed that chronic exposure to D-APV in slices delayed neuronal migration. Calcium imaging experiments revealed that functional NMDA receptors were expressed in neurons and the treatment with D-APV delayed neuronal maturation judging from the subunit composition of NMDA receptor subtypes. The results using pulse-labeling with BrdU indicated that exposure to D-APV for 3 days induced a clear increase in the number of proliferating progenitor cells in the ventricular zone in neocortical slices. Exposure to D-APV in primary cultures also increased the proliferation of progenitor cells. The effect of D-APV on progenitor cell proliferation was possibly mediated through neuronal cells. To elucidate the mechanism of enhanced progenitor cell proliferation induced by D-APV, we investigated expression of Hes1 and Hes5 mRNA in the ventricular zone of neocortical slices by reverse transcription-polymerase chain reaction. Tissue exposed to D-APV for 3 days showed higher expression of Hes1 and Hes5 mRNA than did unexposed control tissue. These results suggest that NMDA receptors expressed in neurons function in neuronal migration and maturation and in the proliferation of progenitor cells.
Collapse
Affiliation(s)
- Takae Hirasawa
- Department of Neurochemistry, National Institute of Neuroscience, Tokyo, Japan
| | | | | | | |
Collapse
|
12
|
Dual regulation of calcium oscillation in astrocytes by growth factors and pro-inflammatory cytokines via the mitogen-activated protein kinase cascade. J Neurosci 2003. [PMID: 14645490 DOI: 10.1523/jneurosci.23-34-10944.2003] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In response to neurotransmitters, astrocytes show various types of calcium increase (transient, oscillatory, and complex), the physiological significance of which is still controversial. To explore this variability, we examined factors affecting the calcium increase pattern in cultured astrocytes and investigated the consequences of the astrocytic calcium response in slice preparations. We found that growth factors (GFs) (EGF plus basic FGF) promoted calcium oscillation in response to glutamate, ATP, or thimerosal (which directly activates the inositol-1,4,5 triphosphate receptor) and that this effect was suppressed by pro-inflammatory cytokines (interleukin-1beta or tumor necrosis factor-alpha), lipopolysaccharide, or a MEK (mitogen-activated protein kinase kinase) inhibitor, suggesting dual regulation of calcium oscillation in astrocytes by factors affecting brain function and pathology via the mitogen-activated protein kinase (MAPK) cascade. The calcium oscillation was accompanied by enlargement of the calcium store, cell proliferation, and the development of a hypertrophic morphology. The cytokines suppressed GF-induced MAPK-dependent immediate early gene promoter activation, but not phosphorylation of extracellular signal-regulated kinase (ERK), showing that they affected gene regulation by acting on the MAPK cascade downstream of ERK. In slice preparations, a metabotropic glutamate receptor agonist converted the spontaneous neuronal calcium increase, attributable to synaptic transmission, to an oscillatory response similar to that seen in astrocytes in culture, indicating that the calcium response in astrocytes acted as a feedback mechanism on the activity of neighboring neurons. This is the first evidence for a dual regulation of calcium oscillation by physiological factors and for the control of calcium dynamics actually being used in physiological processes.
Collapse
|
13
|
Morita M, Higuchi C, Moto T, Kozuka N, Susuki J, Itofusa R, Yamashita J, Kudo Y. Dual regulation of calcium oscillation in astrocytes by growth factors and pro-inflammatory cytokines via the mitogen-activated protein kinase cascade. J Neurosci 2003; 23:10944-52. [PMID: 14645490 PMCID: PMC6740971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
In response to neurotransmitters, astrocytes show various types of calcium increase (transient, oscillatory, and complex), the physiological significance of which is still controversial. To explore this variability, we examined factors affecting the calcium increase pattern in cultured astrocytes and investigated the consequences of the astrocytic calcium response in slice preparations. We found that growth factors (GFs) (EGF plus basic FGF) promoted calcium oscillation in response to glutamate, ATP, or thimerosal (which directly activates the inositol-1,4,5 triphosphate receptor) and that this effect was suppressed by pro-inflammatory cytokines (interleukin-1beta or tumor necrosis factor-alpha), lipopolysaccharide, or a MEK (mitogen-activated protein kinase kinase) inhibitor, suggesting dual regulation of calcium oscillation in astrocytes by factors affecting brain function and pathology via the mitogen-activated protein kinase (MAPK) cascade. The calcium oscillation was accompanied by enlargement of the calcium store, cell proliferation, and the development of a hypertrophic morphology. The cytokines suppressed GF-induced MAPK-dependent immediate early gene promoter activation, but not phosphorylation of extracellular signal-regulated kinase (ERK), showing that they affected gene regulation by acting on the MAPK cascade downstream of ERK. In slice preparations, a metabotropic glutamate receptor agonist converted the spontaneous neuronal calcium increase, attributable to synaptic transmission, to an oscillatory response similar to that seen in astrocytes in culture, indicating that the calcium response in astrocytes acted as a feedback mechanism on the activity of neighboring neurons. This is the first evidence for a dual regulation of calcium oscillation by physiological factors and for the control of calcium dynamics actually being used in physiological processes.
Collapse
Affiliation(s)
- Mitsuhiro Morita
- Laboratory of Cellular Neurobiology, School of Life Science, Tokyo University of Pharmacy and Life Science, 192-0392 Tokyo, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Yoshida Y, Matsumoto N, Tsuchiya R, Morita M, Miyakawa H, Kudo Y. Expression of group I metabotropic glutamate receptors in rat hippocampal cells in culture and their characterization by intracellular calcium ion dynamics. J Pharmacol Sci 2003; 92:245-51. [PMID: 12890890 DOI: 10.1254/jphs.92.245] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
The distribution of group I metabotropic glutamate receptors in rat hippocampal cells in culture was examined by calcium imaging and immunocytochemistry. To distinguish different cell types in the culture, the effects of t-ACPD ((1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid) and of NMDA (N-methyl-D-aspartate) were examined. About 40% of the cultured cells showed either a transient increase or a sustained or oscillatory increase in the intracellular calcium concentration ([Ca(2+)](i)) during t-ACPD administration, while about 60% of the cells showed a sustained [Ca(2+)](i) increase in response to NMDA. Cells that showed an oscillatory [Ca(2+)](i) change during t-ACPD administration did not respond to NMDA administration, while cells that showed a sustained [Ca(2+)](i) increase during NMDA administration did not show any oscillatory response to t-ACPD. After pharmacological examination using those two agonists, the cultured cells were subjected to immunocytochemistry using anti-GFAP and ant-MAP-2 antibodies to distinguish, respectively, astrocytes and neurons. All cells responding to NMDA with a sustained [Ca(2+)](i) increase were MAP-2-positive, whereas all cells showing either oscillatory or sustained [Ca(2+)](i) increase in response to t-ACPD were GFAP-positive. The present results show that, in these cultures, group I metabotropic glutamate receptors are mainly expressed on glial cells and contribute to dynamic [Ca(2+)](i) changes in astrocytes.
Collapse
Affiliation(s)
- Yoshitoku Yoshida
- Laboratory of Cellular Neurobiology, School of Life Science, Tokyo University of Pharmacy and Life Science, Tokyo, Japan
| | | | | | | | | | | |
Collapse
|
15
|
Misiano P, Scott BB, Scheideler MA, Garnier M. PTH2 receptor-mediated inhibitory effect of parathyroid hormone and TIP39 on cell proliferation. Eur J Pharmacol 2003; 468:159-66. [PMID: 12754053 DOI: 10.1016/s0014-2999(03)01673-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The parathyroid hormone (PTH) has dual mitogenic and inhibitory effects on cell proliferation, depending on the cell type and experimental conditions. PTH can signal via two different receptors, both positively coupled to the adenylyl cyclase/cyclic AMP pathway which can mimic some of the proliferative effects of PTH. We evaluated the role of the type-2 PTH (PTH2) receptor on cell proliferation in clonal human embryonic kidney HEK293 cells stably expressing the human PTH2 receptor. Using a cyclic AMP-responsive gene-reporter, we confirmed that the tuberoinfundibular peptide (TIP39) and various human (h) PTH fragments including hPTH-(1-34) were potent agonists (EC(50) in the range of 0.01-0.3 nM) whereas the bovine (b) PTH peptides b(Tyr(34))PTH-(7-34) and its tryptophan derivative b[D-Trp(12),Tyr(34)]PTH-(7-34) behaved as antagonists (IC(50)=117 and 249 nM, respectively). hPTH-(1-34) produced a dose-dependent inhibition of cell proliferation (EC(50)=8.5+/-0.4 nM) after 3 days and this effect was fully reversed by the tryptophan derivative antagonist. The same effect was observed with TIP39 which caused a 30% maximal inhibition. These findings reveal that PTH2 receptor activation can inhibit cell proliferation and might explain the dual functionality of PTH on cell proliferation.
Collapse
Affiliation(s)
- Paola Misiano
- GlaxoSmithKline Pharmaceuticals, Department of Neurobiology Research, Via Zambeletti, 20021 Baranzate di Bollate, Milan, Italy
| | | | | | | |
Collapse
|
16
|
Nishii W, Shoda T, Matsumoto N, Nakamura T, Kudo Y, Takahashi K. In situ visualization of caspase-1-like activity associated with promotion of hippocampal cell death. FEBS Lett 2002; 518:149-53. [PMID: 11997036 DOI: 10.1016/s0014-5793(02)02687-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To clarify the function of caspase-1-like proteases in neuronal cell death, it is important to be able to detect the activity in living organs by microscopic visualization. In the present study, we synthesized a novel fluorescent substrate sensitive to the caspase-1-like activity, which is easily introduced into cells constituting living organs by extracellular application. As a result, the substrate was shown to be useful in imaging the caspase-1-like activity in rat hippocampal slice cultures. After induction of cell death with glutamate, a significant increase in the activity was observed, especially in the pyramidal cells, suggesting the association of the activity with promotion of cell death.
Collapse
Affiliation(s)
- Wataru Nishii
- School of Life Science, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, 192-0392, Tokyo, Japan
| | | | | | | | | | | |
Collapse
|
17
|
Chapter 2 Calcium homeostasis and signaling in aging. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1566-3124(02)10014-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
|
18
|
Kawakami M, Sekiguchi M, Sato K, Kozaki S, Takahashi M. Erythropoietin receptor-mediated inhibition of exocytotic glutamate release confers neuroprotection during chemical ischemia. J Biol Chem 2001; 276:39469-75. [PMID: 11504731 DOI: 10.1074/jbc.m105832200] [Citation(s) in RCA: 187] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Erythropoietin (EPO) reduced Ca(2+)-induced glutamate (Glu) release from cultured cerebellar granule neurons. Inhibition was also produced by EPO mimetic peptide 1 (EMP1), a small synthetic peptide agonist of EPO receptor (EPO-R), but not by iEMP1, an inactive analogue of EMP1. EPO and EMP1 induced autophosphorylation of Janus kinase 2 (JAK2), a tyrosine kinase that associates with EPO-R. Furthermore, genistein, but not genistin, antagonized both the phosphorylation of JAK2 and the suppression of Glu release induced by EPO and EMP1. During chemical ischemia, substantial amounts of Glu were released from cultured cerebellar and hippocampal neurons by at least two distinct mechanisms. In the early phase, Glu release occurred by exocytosis of synaptic vesicle contents, because it was abolished by botulinum type B neurotoxin (BoNT/B). In contrast, the later phase of Glu release mainly involved a BoNT/B-insensitive non-exocytotic pathway. EMP1 inhibited Glu release only during the early exocytotic phase. A 20-min exposure of hippocampal slices to chemical ischemia induced neuronal cell death, especially in the CA1 region and the dentate gyrus, which was suppressed by EMP1 but not iEMP1. However, EMP1 did not attenuate neuronal cell death induced by exogenously applied Glu. These results suggest that activation of EPO-R suppresses ischemic cell death by inhibiting the exocytosis of Glu.
Collapse
Affiliation(s)
- M Kawakami
- Department of Life Sciences (Biology), Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
| | | | | | | | | |
Collapse
|
19
|
Abstract
The mechanisms of central nervous system dysfunction in uremia are multifactorial and only partially characterized. Studies using sealed presynaptic nerve terminals (synaptosomes) for in vitro ion transport and metabolism of neurotransmitter in chronic renal failure (CRF) neuronal cell culture and in vivo brain structure microdialysis generated significant new information. An increase in total calcium content of the cerebral cortex accompanied by increased levels of cytosolic calcium ([Ca(2+)]i) in synaptosomes are common findings in rats with CRF. Mechanisms leading to the increase in [Ca(2+)]i include increased calcium uptake mediated by parathyroid hormone and decreased activity of Na(+),K(+)-adenosine triphosphatase (ATPase) and Ca(2+)-ATPase of synaptosomes in CRF rats. Moreover, these synaptosomes respond inappropriately to depolarization, which can impair neurotransmitter metabolism. Brain gamma-aminobutyric acid content, norepinephrine, and acetylcholine release uptake and degradation are affected by uremia. These may lead to certain somatic, behavioral, and motor dysfunctions in uremia. Many derangements of the central nervous system in uremia appear to be mediated by secondary hyperparathyroidism of CRF because parathyroidectomy of animals with CRF prevented the increase in basal levels of [Ca(2+)]i and derangements in neurotransmitter metabolism. The role of other neurotoxins, such as guanidinosuccinic acid, are also reviewed.
Collapse
Affiliation(s)
- M J Smogorzewski
- Division of Nephrology and Department of Medicine, the Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
| |
Collapse
|
20
|
Suzuki T, Matsugi T, Takagi R, Kanagawa M, Hirata M, Nakamura T, Kudo Y, Kawashima K. Functional expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors precedes the development of cholinergic phenotype in embryonic rat septal cells in culture. Neurosci Lett 2001; 311:89-92. [PMID: 11567785 DOI: 10.1016/s0304-3940(01)02152-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We examined the development of cholinergic neuronal functions and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) responses in cultured embryonic rat septal cells. Choline acetyltransferase activity was increased from 4 to 6 days in culture and reached a plateau at day 8. Acetylcholine release was increased from 6 to 8 days in culture. AMPA-induced increase in intracellular Ca(2+) level was observed at 3 days in culture and most of the AMPA-responsive cells coincided with high-K(+) responsive cells. These results suggest that cholinergic neurons develop their neuronal functions about 8 days under cultured conditions, and functional expression of AMPA receptors precedes the cholinergic functional development.
Collapse
Affiliation(s)
- T Suzuki
- Department of Pharmacology, Kyoritsu College of pharmacy, 1-5-30 Shibakoen, Minatoku, 105-8512, Tokyo, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Usdin TB, Wang T, Hoare SR, Mezey E, Palkovits M. New members of the parathyroid hormone/parathyroid hormone receptor family: the parathyroid hormone 2 receptor and tuberoinfundibular peptide of 39 residues. Front Neuroendocrinol 2000; 21:349-83. [PMID: 11013069 DOI: 10.1006/frne.2000.0203] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The parathyroid hormone (PTH) family currently includes three peptides and three receptors. PTH regulates calcium homeostasis through bone and kidney PTH1 receptors. PTH-related peptide, probably also through PTH1 receptors, regulates skeletal, pancreatic, epidermal, and mammary gland differentiation and bladder and vascular smooth muscle relaxation and has a CNS role that is under investigation. Tuberoinfundibular peptide of 39 residues (TIP39) was recently purified from bovine hypothalamus based on selective PTH2 receptor activation. PTH2 receptor expression is greatest in the CNS, where it is concentrated in limbic, hypothalamic, and sensory areas, especially hypothalamic periventricular neurons, nerve terminals in the median eminence, superficial layers of the spinal cord dorsal horn, and the caudal part of the sensory trigeminal nucleus. It is also present in a number of endocrine cells. Thus TIP39 and PTH2 receptor-influenced functions may range from pituitary and pancreatic hormone release to pain perception. A third PTH-recognizing receptor has been found in zebrafish.
Collapse
Affiliation(s)
- T B Usdin
- Laboratory of Genetics, National Institute of Mental Health, Bethesda, Maryland 20892-4094, USA.
| | | | | | | | | |
Collapse
|
22
|
Whitfield J, Morley P, Willick G. The parathyroid hormone, its fragments and analogues--potent bone-builders for treating osteoporosis. Expert Opin Investig Drugs 2000; 9:1293-315. [PMID: 11060744 DOI: 10.1517/13543784.9.6.1293] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
As populations age a rising number of men and women, but especially women during the first decade after menopause, become victims of a severe, accelerated loss of bone with crippling fractures known as osteoporosis. This often results in costly, prolonged hospitalisation and perhaps indirectly, death. Osteoporosis in women is caused by the menopausal oestrogen decline, which removes several key restraints on the generation, longevity and activity of bone-resorbing osteoclasts. Although there are many antiresorptive drugs on or coming onto the market (calcitonin, bisphosphonates, oestrogen and SERMS) that can slow or stop further bone loss, there are none that can restore lost bone mechanical strength by directly stimulating osteoblast activity and bone growth. However, there is a family of potent bone-building peptides, namely the 84 amino acid parathyroid hormone (PTH). Its 31 to 38 amino acid N-terminal fragments are currently in or about to enter clinical trials. We can predict that these peptides will be effective therapeutics for osteoporosis especially when supplemented with bisphosphonates or SERMs to protect the new bone from osteoclasts. These peptides should also accelerate the healing of fractures in persons of all ages and restore lost bone mass and mechanical strength to astronauts following their return to earth after long voyages in space.
Collapse
Affiliation(s)
- J Whitfield
- Institute for Biological Sciences, National Research Council of Canada, Bldg. M-54, Montreal Road Campus, Ottawa, ON, Canada K1A 0R6.
| | | | | |
Collapse
|