1
|
Morimoto K, Eguchi R, Kitano T, Otsuguro KI. Alpha and beta adrenoceptors activate interleukin-6 transcription through different pathways in cultured astrocytes from rat spinal cord. Cytokine 2021; 142:155497. [PMID: 33770644 DOI: 10.1016/j.cyto.2021.155497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 03/05/2021] [Accepted: 03/08/2021] [Indexed: 01/10/2023]
Abstract
In brain astrocytes, noradrenaline (NA) has been shown to up-regulate IL-6 production via β-adrenoceptors (ARs). However, the underlying intracellular mechanisms for this regulation are not clear, and it remains unknown whether α-ARs are involved. In this study, we investigated the AR-mediated regulation of IL-6 mRNA levels in the cultured astrocytes from rat spinal cord. NA, the α1-agonist phenylephrine, and the β-agonist isoproterenol increased IL-6 mRNA levels. The phenylephrine-induced IL-6 increase was accompanied by an increase in ERK phosphorylation, and these effects were blocked by inhibitors of PKC and ERK. The isoproterenol-induced IL-6 increase was accompanied by an increase in CREB phosphorylation, and these effects were blocked by a PKA inhibitor. Our results indicate that IL-6 increases by α1- and β-ARs are mediated via the PKC/ERK and cAMP/PKA/CREB pathways, respectively. Moreover, conditioned medium collected from astrocytes treated with the α2-AR agonist dexmedetomidine, increased IL-6 mRNA in other astrocytes. In this study, we elucidate that α1- and α2-ARs, in addition to β-ARs, promote IL-6 transcription through different pathways in spinal cord astrocytes.
Collapse
MESH Headings
- Adrenergic alpha-Agonists/pharmacology
- Adrenergic alpha-Antagonists/pharmacology
- Adrenergic beta-Agonists/pharmacology
- Adrenergic beta-Antagonists/pharmacology
- Animals
- Astrocytes/drug effects
- Astrocytes/metabolism
- Cells, Cultured
- Culture Media, Conditioned/pharmacology
- Interleukin-6/genetics
- Interleukin-6/metabolism
- Protein Kinase Inhibitors/pharmacology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats, Wistar
- Receptors, Adrenergic, alpha/metabolism
- Receptors, Adrenergic, beta/metabolism
- Signal Transduction/drug effects
- Signal Transduction/genetics
- Spinal Cord/cytology
- Transcription, Genetic/drug effects
- Transcriptional Activation/drug effects
- Transcriptional Activation/genetics
- Rats
Collapse
Affiliation(s)
- Kohei Morimoto
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo 060-0818, Japan
| | - Ryota Eguchi
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo 060-0818, Japan
| | - Taisuke Kitano
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo 060-0818, Japan
| | - Ken-Ichi Otsuguro
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo 060-0818, Japan.
| |
Collapse
|
2
|
Kitano T, Eguchi R, Okamatsu-Ogura Y, Yamaguchi S, Otsuguro KI. Opposing functions of α- and β-adrenoceptors in the formation of processes by cultured astrocytes. J Pharmacol Sci 2021; 145:228-240. [PMID: 33602503 DOI: 10.1016/j.jphs.2020.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/07/2020] [Accepted: 12/17/2020] [Indexed: 10/22/2022] Open
Abstract
Astrocytes are glial cells with numerous fine processes which are important for the functions of the central nervous system. The activation of β-adrenoceptors induces process formation of astrocytes via cyclic AMP (cAMP) signaling. However, the role of α-adrenoceptors in the astrocyte morphology has not been elucidated. Here, we examined it by using cultured astrocytes from neonatal rat spinal cords and cortices. Exposure of these cells to noradrenaline and the β-adrenoceptor agonist isoproterenol increased intracellular cAMP levels and induced the formation of processes. Noradrenaline-induced process formation was enhanced with the α1-adrenoceptor antagonist prazosin and α2-adrenoceptor antagonist atipamezole. Atipamezole also enhanced noradrenaline-induced cAMP elevation. Isoproterenol-induced process formation was not inhibited by the α1-adrenoceptor agonist phenylephrine but was inhibited by the α2-adrenoceptor agonist dexmedetomidine. Dexmedetomidine also inhibited process formation induced by the adenylate cyclase activator forskolin and the membrane-permeable cAMP analog dibutyryl-cAMP. Moreover, dexmedetomidine inhibited cAMP-independent process formation induced by adenosine or the Rho-associated kinase inhibitor Y27632. In the presence of propranolol, noradrenaline inhibited Y27632-induced process formation, which was abolished by prazosin or atipamezole. These results demonstrate that α-adrenoceptors inhibit both cAMP-dependent and -independent astrocytic process formation.
Collapse
Affiliation(s)
- Taisuke Kitano
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan
| | - Ryota Eguchi
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan
| | - Yuko Okamatsu-Ogura
- Laboratory of Biochemistry, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan
| | - Soichiro Yamaguchi
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan
| | - Ken-Ichi Otsuguro
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan.
| |
Collapse
|
3
|
Peng M, Ling X, Song R, Gao X, Liang Z, Fang F, Cang J. Upregulation of GLT-1 via PI3K/Akt Pathway Contributes to Neuroprotection Induced by Dexmedetomidine. Front Neurol 2019; 10:1041. [PMID: 31611842 PMCID: PMC6776610 DOI: 10.3389/fneur.2019.01041] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 09/13/2019] [Indexed: 12/30/2022] Open
Abstract
Perioperative ischemic stroke usually leads to neurological dysfunction caused by neuron death. During the ischemic condition, excitotoxity due to extracellular glutamate accumulation is a main mechanism of neuron damage. The clearance of glutamate mainly depends on glutamate transporter-1 (GLT-1) which is expressed in astrocytes. Dexmedetomidine, an α2 adrenergic receptor agonist, is proved to induce neuroprotection. This study was set out to investigate the glutamate-related mechanism involved in the neuroprotective effect of dexmedetomidine. Middle cerebral artery occlusion (MCAO) was used as a model of ischemic stroke in our study. We determined Neurological deficit scores (NDS) and Magnetic resonance imaging (MRI) at three points (2, 6, and 24 h) after middle cerebral artery occlusion (MCAO) to evaluate the neuroprotective effect of dexmedetomidine. Besides, we performed western blot (6 and 24 h after MACO) and immunofluorescent staining (24 h after MCAO) to observe the expression of GLT-1. The effect and mechanism of dexmedetomidine on GLT-1 in primary cultured astrocytes were investigated using western blot and RT-PCR. Our results showed that pretreatment with dexmedetomidine improved NDS and reduced infarct volume as well as upregulating GLT-1 expression. Furthermore, using Atipamezole and LY294002, we found that dexmedetomidine significantly increased GLT-1 levels in astrocytes via activating α2 adrenergic receptor and PI3K/AKT pathway both in vitro and in vivo study. Overall, our present study indicated that dexmedetomidine had neuroprotective effects on ischemia stroke and upregulation of GLT-1 levels by PI3K/AKT dependent pathway might be the potential mechanism.
Collapse
Affiliation(s)
- Mengyuan Peng
- Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Xiaomin Ling
- Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Ruixue Song
- Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Xuan Gao
- Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Zhifeng Liang
- Comparative Nerve Imaging Study Group, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Fang Fang
- Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jing Cang
- Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, China
| |
Collapse
|
4
|
Kushwaha R, Mishra J, Gupta AP, Gupta K, Vishwakarma J, Chattopadhyay N, Gayen JR, Kamthan M, Bandyopadhyay S. Rosiglitazone up-regulates glial fibrillary acidic protein via HB-EGF secreted from astrocytes and neurons through PPARγ pathway and reduces apoptosis in high-fat diet-fed mice. J Neurochem 2018; 149:679-698. [PMID: 30311190 DOI: 10.1111/jnc.14610] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 09/27/2018] [Accepted: 10/06/2018] [Indexed: 12/17/2022]
Abstract
The anti-diabetic drug and peroxisome proliferator-activated receptor-gamma (PPARγ) agonist, rosiglitazone, alters astrocyte activation; however, its mechanism remains less-known. We hypothesized participation of epidermal growth factor receptor (EGFR), known to control astrocyte reactivity. We first detected that rosiglitazone promoted glial fibrillary acidic protein (GFAP) expression in primary astrocytes as well as the mouse cerebral cortex, associated with increased EGFR activation. Screening for EGFR ligands revealed a rosiglitazone-mediated increase of heparin-binding epidermal growth factor (HB-EGF) in astrocytes, resulting in HB-EGF release into culture medium and mouse cerebrospinal fluid too. Treatment with HB-EGF-siRNA and EGFR inhibitors showed that the rosiglitazone-induced HB-EGF and p-EFGR were interdependent, which participated in GFAP increase. Interestingly, we observed that rosiglitazone could induce cellular and secreted-HB-EGF in neurons also, contributing toward the activated EGFR-induced GFAP in astrocytes. Probing whether these effects of rosiglitazone were PPARγ-linked, revealed potential PPARγ-responsive elements within HB-EGF gene. Moreover, gel-shift, site-directed mutagenesis, chromatin-immunoprecipitation and luciferase-reporter assays demonstrated a PPARγ-dependent HB-EGF transactivation. Subsequently, we examined effects of rosiglitazone in a high-fat diet-fed diabetes mouse model, and supporting observations in the normal cortical cells, identified a rosiglitazone-induced GFAP, astrocyte and neuronal HB-EGF and secreted-HB-EGF in the cerebral cortex of diabetic mice. Moreover, assessing relevance of increased HB-EGF and GFAP revealed an anti-apoptotic role of rosiglitazone in the cerebral cortex, supported by a GFAP-siRNA as well as HB-EGF-siRNA-mediated increase in cleaved-caspase 3 and 9 levels in the rosiglitazone-treated astrocyte-neuron coculture. Overall, our study indicates that rosiglitazone may protect the brain, via a PPARγ-dependent HB-EGF/EGFR signaling and increased GFAP.
Collapse
Affiliation(s)
- Rajesh Kushwaha
- Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR campus, Lucknow, India.,Developmental Toxicology Laboratory, Systems Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (IITR), Lucknow, India
| | - Juhi Mishra
- Developmental Toxicology Laboratory, Systems Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (IITR), Lucknow, India.,Babu Banarasi Das University, Lucknow, India
| | - Anand Prakash Gupta
- Pharmaceutics and Pharmacokinetics, CSIR-Central Drug Research Institute (CDRI), Lucknow, India
| | - Keerti Gupta
- Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR campus, Lucknow, India.,Developmental Toxicology Laboratory, Systems Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (IITR), Lucknow, India
| | - Jitendra Vishwakarma
- Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR campus, Lucknow, India.,Developmental Toxicology Laboratory, Systems Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (IITR), Lucknow, India
| | - Naibedya Chattopadhyay
- Department of Endocrinology, CSIR-Central Drug Research Institute (CDRI), Lucknow, India
| | - Jiaur Rahaman Gayen
- Pharmaceutics and Pharmacokinetics, CSIR-Central Drug Research Institute (CDRI), Lucknow, India
| | - Mohan Kamthan
- Environmental Biotechnology Laboratory, Environmental Toxicology Group, CSIR-IITR, Lucknow, India
| | - Sanghamitra Bandyopadhyay
- Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR campus, Lucknow, India.,Developmental Toxicology Laboratory, Systems Toxicology & Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (IITR), Lucknow, India
| |
Collapse
|
5
|
Dexmedetomidine Prevents Excessive γ-Aminobutyric Acid Type A Receptor Function after Anesthesia. Anesthesiology 2018; 129:477-489. [DOI: 10.1097/aln.0000000000002311] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Abstract
What We Already Know about This Topic
What This Article Tells Us That Is New
Background
Postoperative delirium is associated with poor long-term outcomes and increased mortality. General anesthetic drugs may contribute to delirium because they increase cell-surface expression and function of α5 subunit-containing γ-aminobutyric acid type A receptors, an effect that persists long after the drugs have been eliminated. Dexmedetomidine, an α2 adrenergic receptor agonist, prevents delirium in patients and reduces cognitive deficits in animals. Thus, it was postulated that dexmedetomidine prevents excessive function of α5 γ-aminobutyric acid type A receptors.
Methods
Injectable (etomidate) and inhaled (sevoflurane) anesthetic drugs were studied using cultured murine hippocampal neurons, cultured murine and human cortical astrocytes, and ex vivo murine hippocampal slices. γ-Aminobutyric acid type A receptor function and cell-signaling pathways were studied using electrophysiologic and biochemical methods. Memory and problem-solving behaviors were also studied.
Results
The etomidate-induced sustained increase in α5 γ-aminobutyric acid type A receptor cell-surface expression was reduced by dexmedetomidine (mean ± SD, etomidate: 146.4 ± 51.6% vs. etomidate + dexmedetomidine: 118.4 ± 39.1% of control, n = 8 each). Dexmedetomidine also reduced the persistent increase in tonic inhibitory current in hippocampal neurons (etomidate: 1.44 ± 0.33 pA/pF, n = 10; etomidate + dexmedetomidine: 1.01 ± 0.45 pA/pF, n = 9). Similarly, dexmedetomidine prevented a sevoflurane-induced increase in the tonic current. Dexmedetomidine stimulated astrocytes to release brain-derived neurotrophic factor, which acted as a paracrine factor to reduce excessive α5 γ-aminobutyric acid type A receptor function in neurons. Finally, dexmedetomidine attenuated memory and problem-solving deficits after anesthesia.
Conclusions
Dexmedetomidine prevented excessive α5 γ-aminobutyric acid type A receptor function after anesthesia. This novel α2 adrenergic receptor- and brain-derived neurotrophic factor-dependent pathway may be targeted to prevent delirium.
Collapse
|
6
|
Kushwaha R, Mishra J, Tripathi S, Raza W, Mandrah K, Roy SK, Bandyopadhyay S. Arsenic Attenuates Heparin-Binding EGF-Like Growth Factor/EGFR Signaling That Promotes Matrix Metalloprotease 9-Dependent Astrocyte Damage in the Developing Rat Brain. Toxicol Sci 2017; 162:406-428. [DOI: 10.1093/toxsci/kfx264] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Affiliation(s)
- Rajesh Kushwaha
- Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR Campus, Lucknow, India
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, India
| | - Juhi Mishra
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, India
- Babu Banarasi Das University, Lucknow 226028, India
| | - Sachin Tripathi
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, India
- Amity Institute of Biotechnology, Amity University (Lucknow Campus), Lucknow, India
| | - Waseem Raza
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, India
| | - Kapil Mandrah
- Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR Campus, Lucknow, India
- Analytical Chemistry Laboratory and Regulatory Toxicology Group, CSIR-IITR, Lucknow, India
| | - Somendu Kumar Roy
- Analytical Chemistry Laboratory and Regulatory Toxicology Group, CSIR-IITR, Lucknow, India
| | - Sanghamitra Bandyopadhyay
- Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR Campus, Lucknow, India
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Lucknow 226001, India
| |
Collapse
|
7
|
Ji D, Zhou Y, Li S, Li D, Chen H, Xiong Y, Zhang Y, Xu H. Anti-nociceptive effect of dexmedetomidine in a rat model of monoarthritis via suppression of the TLR4/NF-κB p65 pathway. Exp Ther Med 2017; 14:4910-4918. [PMID: 29201195 PMCID: PMC5704272 DOI: 10.3892/etm.2017.5196] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 06/02/2017] [Indexed: 01/13/2023] Open
Abstract
As a therapeutic target for neuropathic pain, the anti-nociceptive effects of α 2-adrenoceptors (α2AR) have attracted attention. Dexmedetomidine (DEX), a potent and highly selective α2AR agonist, has exhibited significant analgesic effects in neuropathic pain, but the underlying mechanism has remained elusive. The present study investigated the effect of DEX on Toll-like receptor (TLR)4 and nuclear factor (NF)-κB p65 expression, as well as the production of pro-inflammatory cytokines. The rat monoarthritis (MA) model was induced by intra-articular injection of complete Freund's adjuvant (CFA) at the ankle joint. After induction of MA, the rats were intrathecally treated with normal saline or DEX (2.5 µg) for 3 consecutive days. The concentration of interleukin-1β and -6 as well as tumor necrosis factor-α was examined by ELISA. The expression levels of TLR4 and NF-κB p65 were determined by western blot analysis and immunohistochemistry. The results indicated that the pro-inflammatory cytokines TLR4 and NF-κB p65 were significantly upregulated in MA rats. DEX treatment markedly reduced mechanical and thermal hyperalgesia, suppressed MA-induced elevation of the pro-inflammatory cytokines and inhibited the TLR4/NF-κB p65 pathway, while these effects were blocked by pre-treatment with the selective α2AR antagonist BRL44408 (15 µg) at 30 min prior to CFA injection. These results suggested that DEX has an anti-nociceptive effect via suppressing the TLR4/NF-κB p65 pathway.
Collapse
Affiliation(s)
- Dong Ji
- Department of Anesthesiology, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
| | - Yalan Zhou
- Department of Anesthesiology, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
| | - Shuangshuang Li
- Department of Anesthesiology, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
| | - Dai Li
- Department of Anesthesiology, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
| | - Hui Chen
- Department of Anesthesiology, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
| | - Yuanchang Xiong
- Department of Anesthesiology, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
| | - Yuqiu Zhang
- Institute of Neurobiology, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, P.R. China
| | - Hua Xu
- Department of Anesthesiology, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
| |
Collapse
|
8
|
Zhou J, Du T, Li B, Rong Y, Verkhratsky A, Peng L. Crosstalk Between MAPK/ERK and PI3K/AKT Signal Pathways During Brain Ischemia/Reperfusion. ASN Neuro 2015; 7:7/5/1759091415602463. [PMID: 26442853 PMCID: PMC4601130 DOI: 10.1177/1759091415602463] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The epidermal growth factor receptor (EGFR) is linked to the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) and Raf/mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK1/2) signaling pathways. During brain ischemia/reperfusion, EGFR could be transactivated, which stimulates these intracellular signaling cascades that either protect cells or potentiate cell injury. In the present study, we investigated the activation of EGFR, PI3K/AKT, and Raf/MAPK/ERK1/2 during ischemia or reperfusion of the brain using the middle cerebral artery occlusion model. We found that EGFR was phosphorylated and transactivated during both ischemia and reperfusion periods. During ischemia, the activity of PI3K/AKT pathway was significantly increased, as judged from the strong phosphorylation of AKT; this activation was suppressed by the inhibitors of EGFR and Zn-dependent metalloproteinase. Ischemia, however, did not induce ERK1/2 phosphorylation, which was dependent on reperfusion. Coimmunoprecipitation of Son of sevenless 1 (SOS1) with EGFR showed increased association between the receptor and SOS1 in ischemia, indicating the inhibitory node downstream of SOS1. The inhibitory phosphorylation site of Raf-1 at Ser259, but not its stimulatory phosphorylation site at Ser338, was phosphorylated during ischemia. Furthermore, ischemia prompted the interaction between Raf-1 and AKT, while both the inhibitors of PI3K and AKT not only abolished AKT phosphorylation but also restored ERK1/2 phosphorylation. All these findings suggest that Raf/MAPK/ERK1/2 signal pathway is inhibited by AKT via direct phosphorylation and inhibition at Raf-1 node during ischemia. During reperfusion, we observed a significant increase of ERK1/2 phosphorylation but no change in AKT phosphorylation. Inhibitors of reactive oxygen species and phosphatase and tensin homolog restored AKT phosphorylation but abolished ERK1/2 phosphorylation, suggesting that the reactive oxygen species-dependent increase in phosphatase and tensin homolog activity in reperfusion period relieves ERK1/2 from inhibition of AKT.
Collapse
Affiliation(s)
- Jing Zhou
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, P. R. China
| | - Ting Du
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, P. R. China
| | - Baoman Li
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, P. R. China
| | - Yan Rong
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, P. R. China
| | - Alexei Verkhratsky
- Faculty of Life Science, The University of Manchester, UK Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain University of Nizhny Novgorod, Russia
| | - Liang Peng
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, P. R. China
| |
Collapse
|
9
|
Liang C, Du T, Zhou J, Verkhratsky A, Peng L. Ammonium increases Ca(2+) signalling and up-regulates expression of TRPC1 gene in astrocytes in primary cultures and in the in vivo brain. Neurochem Res 2014; 39:2127-35. [PMID: 25113123 DOI: 10.1007/s11064-014-1406-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/29/2014] [Accepted: 07/30/2014] [Indexed: 12/12/2022]
Abstract
Rapid rise in ammonium concentration in the brain is the major pathogenic factor in hepatic encephalopathy that is manifested by state of confusion, forgetfulness and irritability, psychotic symptoms, delusions, lethargy, somnolence and, in the terminal stages, coma. Primary cultures of mouse astrocytes were used to investigate effects of chronic treatment (3 days) with ammonium chloride (ammonium) at 3 mM, this being a relevant concentration for hepatic encephalopathy condition, on metabotropic receptor agonist-induced increases in free cytosolic Ca(2+) concentration [(Ca(2+))i], measured with fura-2 based microfluorimetry and on store-operated Ca(2+) entry (SOCE) activated following treatment with the SERCA inhibitor thapsigargin. The agonists used were the β-adrenergic agonist isoproterenol, the α2-adrenergic agonist dexmedetomidine, the InsP3 receptor (InsP3R) agonist adenophostin A and ryanodine receptor agonist 4-Chloro-m-cresol (4-CMC). Agonist-induced [Ca(2+)]i responses were significantly increased in astrocytes chronically exposed to ammonium. Similarly, the SOCE, meditated by the transient receptor potential channel 1 (TRPC1), was significantly augmented. The ammonium-induced increase in SOCE was a result of an up-regulation of mRNA and protein expression of TRPC1 in astrocytes. Increase in TRPC1 expression and in SOCE were both prevented by ouabain antagonist canrenone. Similar up-regulation of TRPC1 gene expression was found in the brain of adult mice subjected to intraperitoneal injection of urease for 3 days. In transgenic mice tagged with an astrocyte-specific or a neurone-specific markers and treated with intraperitoneal injections of urease for 3 days, the fluorescence-activated cell sorting of neurones and astrocytes demonstrated that TRPC1 mRNA expression was up-regulated in astrocytes, but not in neurones.
Collapse
Affiliation(s)
- Chunguang Liang
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, No. 92 Beier Road, Heping District, Shenyang, People's Republic of China
| | | | | | | | | |
Collapse
|
10
|
Inflammatory Response in Patients under Coronary Artery Bypass Grafting Surgery and Clinical Implications: A Review of the Relevance of Dexmedetomidine Use. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/905238] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Despite the fact that coronary artery bypass grafting surgery (CABG) with cardiopulmonary bypass (CPB) prolongs life and reduces symptoms in patients with severe coronary artery diseases, these benefits are accompanied by increased risks. Morbidity associated with cardiopulmonary bypass can be attributed to the generalized inflammatory response induced by blood-xenosurfaces interactions during extracorporeal circulation and the ischemia/reperfusion implications, including exacerbated inflammatory response resembling the systemic inflammatory response syndrome (SIRS). The use of specific anesthetic agents with anti-inflammatory activity can modulate the deleterious inflammatory response. Consequently, anti-inflammatory anesthetics may accelerate postoperative recovery and better outcomes than classical anesthetics. It is known that the stress response to surgery can be attenuated by sympatholytic effects caused by activation of central (α-)2-adrenergic receptor, leading to reductions in blood pressure and heart rate, and more recently, that they can have anti-inflammatory properties. This paper discusses the clinical significance of the dexmedetomidine use, a selective (α-)2-adrenergic agonist, as a coadjuvant in general anesthesia. Actually, dexmedetomidine use is not in anesthetic routine, but this drug can be considered a particularly promising agent in perioperative multiple organ protection.
Collapse
|
11
|
Gao M, Zhan YQ, Yu M, Ge CH, Li CY, Zhang JH, Wang XH, Ge ZQ, Yang XM. Hepassocin activates the EGFR/ERK cascade and induces proliferation of L02 cells through the Src-dependent pathway. Cell Signal 2014; 26:2161-6. [PMID: 24768768 DOI: 10.1016/j.cellsig.2014.04.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 04/11/2014] [Indexed: 12/26/2022]
Abstract
Hepassocin (HPS) is a secreted protein with mitogenic activity on primary hepatocytes and protects hepatocytes from chemically-induced injury. Our previous studies showed that HPS stimulates proliferation of hepatocytes in an ERK pathway-dependent manner. However, the molecular mechanism of HPS-induced activation of the ERK pathway remains unclear. In this study, we found that HPS induced the phosphorylation of the epidermal growth factor receptor (EGFR) in the human L02 hepatocyte cell line, and this event was concomitant with the activation of the non-receptor tyrosine kinase Src. Specific inhibition of EGFR kinase activity by gefitinib or down-regulation of EGFR by specific EGFR siRNAs prevented HPS-induced activation of the ERK pathway and proliferation of L02 cells. Furthermore, inhibition of Src activity significantly blocked HPS-induced activation of the EGFR, which was suggestive of a ligand-independent transactivation mechanism of EGFR itself as well as ERK phosphorylation and proliferation of L02 cells. These results indicate that EGFR plays an important role in the mitogenic signaling induced by HPS in L02 cell lines and may further stimulate research on the role of HPS in hepatocytes within biological processes in human health and disease.
Collapse
Affiliation(s)
- Ming Gao
- Tianjin University, Department of Pharmaceutical Engineering, Tianjin 300072, China; Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Yi-Qun Zhan
- Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China
| | - Miao Yu
- Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China
| | - Chang-Hui Ge
- Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China
| | - Chang-Yan Li
- Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China
| | - Jian-Hong Zhang
- Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China
| | - Xiao-Hui Wang
- Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China
| | - Zhi-Qiang Ge
- Tianjin University, Department of Pharmaceutical Engineering, Tianjin 300072, China
| | - Xiao-Ming Yang
- Tianjin University, Department of Pharmaceutical Engineering, Tianjin 300072, China; Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China.
| |
Collapse
|
12
|
Phamduong E, Rathore MK, Crews NR, D’Angelo AS, Leinweber AL, Kappera P, Krenning TM, Rendell VR, Belcheva MM, Coscia CJ. Acute and chronic mu opioids differentially regulate thrombospondins 1 and 2 isoforms in astrocytes. ACS Chem Neurosci 2014; 5:106-14. [PMID: 24304333 DOI: 10.1021/cn400172n] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Chronic opioids induce synaptic plasticity, a major neuronal adaptation. Astrocyte activation in synaptogenesis may play a critical role in opioid tolerance, withdrawal, and dependence. Thrombospondins 1 and 2 (TSP1/2) are astrocyte-secreted matricellular glycoproteins that promote neurite outgrowth as well as dendritic spine and synapse formation, all of which are inhibited by chronic μ opioids. In prior studies, we discovered that the mechanism of TSP1 regulation by μ opioids in astrocytes involves crosstalk between three different classes of receptors, μ opioid receptor, EGFR and TGFβR. Moreover, TGFβ1 stimulated TSP1 expression via EGFR and ERK/MAPK activation, indicating that EGFR is a signaling hub for opioid and TGFβ1 actions. Using various selective antagonists, and inhibitors, here we compared the mechanisms of chronic opioid regulation of TSP1/2 isoform expression in vivo and in immortalized rat cortical astrocytes. TSP1/2 release from astrocytes was also monitored. Acute and chronic μ opioids, morphine, and the prototypic μ ligand, DAMGO, modulated TSP2 protein levels. TSP2 but not TSP1 protein content was up-regulated by acute (3 h) morphine or DAMGO by an ERK/MAPK dependent mechanism. Paradoxically, TSP2 protein levels were altered neither by TGFβ1 nor by astrocytic neurotrophic factors, EGF, CNTF, and BMP4. TSP1/2 immunofluorescence was increased in astrocytes subjected to scratch-wounding, suggesting TSPs may be useful markers for the "reactive" state of these cells and potentially for different types of injury. Previously, we determined that chronic morphine attenuated both neurite outgrowth and synapse formation in cocultures of primary astrocytes and neurons under similar temporal conditions that μ opioids reduced TSP1 protein levels in astrocytes. Here we found that, after the same 8 day treatment, morphine or DAMGO diminished TSP2 protein levels in astrocytes. Therefore, μ opioids may deter synaptogenesis via both TSP1/2 isoforms, but by distinct mechanisms.
Collapse
Affiliation(s)
- Ellen Phamduong
- E. A. Doisy Department of
Biochemistry and Molecular Biology, St. Louis University of Medicine, 1100 S. Grand Blvd., St. Louis, Missouri, 63104, United States
| | - Maanjot K. Rathore
- E. A. Doisy Department of
Biochemistry and Molecular Biology, St. Louis University of Medicine, 1100 S. Grand Blvd., St. Louis, Missouri, 63104, United States
| | - Nicholas R. Crews
- E. A. Doisy Department of
Biochemistry and Molecular Biology, St. Louis University of Medicine, 1100 S. Grand Blvd., St. Louis, Missouri, 63104, United States
| | - Alexander S. D’Angelo
- E. A. Doisy Department of
Biochemistry and Molecular Biology, St. Louis University of Medicine, 1100 S. Grand Blvd., St. Louis, Missouri, 63104, United States
| | - Andrew L. Leinweber
- E. A. Doisy Department of
Biochemistry and Molecular Biology, St. Louis University of Medicine, 1100 S. Grand Blvd., St. Louis, Missouri, 63104, United States
| | - Pranay Kappera
- E. A. Doisy Department of
Biochemistry and Molecular Biology, St. Louis University of Medicine, 1100 S. Grand Blvd., St. Louis, Missouri, 63104, United States
| | - Thomas M. Krenning
- E. A. Doisy Department of
Biochemistry and Molecular Biology, St. Louis University of Medicine, 1100 S. Grand Blvd., St. Louis, Missouri, 63104, United States
| | - Victoria R. Rendell
- E. A. Doisy Department of
Biochemistry and Molecular Biology, St. Louis University of Medicine, 1100 S. Grand Blvd., St. Louis, Missouri, 63104, United States
| | - Mariana M. Belcheva
- E. A. Doisy Department of
Biochemistry and Molecular Biology, St. Louis University of Medicine, 1100 S. Grand Blvd., St. Louis, Missouri, 63104, United States
| | - Carmine J. Coscia
- E. A. Doisy Department of
Biochemistry and Molecular Biology, St. Louis University of Medicine, 1100 S. Grand Blvd., St. Louis, Missouri, 63104, United States
| |
Collapse
|
13
|
Zhang M, Shan X, Gu L, Hertz L, Peng L. Dexmedetomidine causes neuroprotection via astrocytic α2- adrenergic receptor stimulation and HB-EGF release. ACTA ACUST UNITED AC 2013. [DOI: 10.7243/2049-9752-2-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
14
|
Rangel RAS, Marinho BG, Fernandes PD, de Moura RS, Lessa MA. Pharmacological mechanisms involved in the antinociceptive effects of dexmedetomidine in mice. Fundam Clin Pharmacol 2012; 28:104-13. [PMID: 22924641 DOI: 10.1111/j.1472-8206.2012.01068.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 07/12/2012] [Accepted: 07/19/2012] [Indexed: 11/30/2022]
Abstract
Dexmedetomidine (DEX) is a α₂ -adrenoceptor (α₂ -AR) agonist used as an anesthetic adjuvant and as sedative in critical care settings. Typically, α₂ -AR agonists release nitric oxide (NO) and subsequently activate NO-GMPc pathway and have been implicated with antinociception. In this study, we investigate the pharmacological mechanisms involved in the antinociceptive effects of DEX, using an acetic acid-induced writhing assay in mice. Saline or DEX (1, 2, 5, or 10 μg/kg) was intravenously injected 5 min before ip administration of acetic acid and the resulting abdominal constrictions were then counted for 10 min. To investigate the possible mechanisms related to antinociceptive effect of DEX (10 μg/kg), the animals were also pretreated with one of the following drugs: 7-nitroindazole (7-NI; 30 mg/kg ip); 1H-[1,2,4] oxadiazole [4,3-a] quinoxaline-1-one (ODQ; 2.5 mg/kg, ip); yohimbine (YOH; 1 mg/kg, ip); atropine (ATRO; 2 mg/kg, ip); glibenclamide (GLIB; 1 mg/kg, i.p.) and naloxone (NAL; 0.2 mg/kg, ip). A rotarod and open-field performance test were performed with DEX at 10 μg/kg dose. DEX demonstrated its potent antinociceptive effect in a dose-dependent manner. The pretreatment with 7-NI, ODQ, GLIB, ATRO, and YOH significantly reduced the antinociceptive affects of DEX. However, NAL showed no effecting DEX-induced antinociception. The rotarod and open-field tests confirmed there is no detectable sedation or even significant motor impairment with DEX at 10 μg/kg dose. Our results suggest that the α₂ -AR and NO-GMPc pathways play important roles in the systemic antinociceptive effect of DEX in a murine model of inflammatory pain. Furthermore, the antinociceptive effect exerted by DEX appears to be dependent on KATP channels, independent of opioid receptor activity.
Collapse
Affiliation(s)
- Rafael A S Rangel
- Department of Pharmacology and Psychobiology, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | | | | | | | | |
Collapse
|
15
|
Inhibition by dexmedetomidine of the activation of spinal dorsal horn glias and the intracellular ERK signaling pathway induced by nerve injury. Brain Res 2012; 1427:1-9. [DOI: 10.1016/j.brainres.2011.08.019] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 08/08/2011] [Accepted: 08/09/2011] [Indexed: 01/01/2023]
|
16
|
Li B, Dong L, Fu H, Wang B, Hertz L, Peng L. Effects of chronic treatment with fluoxetine on receptor-stimulated increase of [Ca2+]i in astrocytes mimic those of acute inhibition of TRPC1 channel activity. Cell Calcium 2011; 50:42-53. [PMID: 21640379 DOI: 10.1016/j.ceca.2011.05.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 04/30/2011] [Accepted: 05/03/2011] [Indexed: 12/17/2022]
Abstract
Primary cultures of mouse astrocytes were used to investigate effects by chronic treatment (3-21 days) with fluoxetine (0.5-10 μM) on capacitative Ca(2+) influx after treatment with the SERCA inhibitor thapsigargin and on receptor agonist-induced increases in free cytosolic Ca(2+) concentration [Ca(2+)](i), determined with Fura-2. The agonists were the 5-HT(2B) agonist fluoxetine, the α(2)-adrenergic agonist dexmedetomidine, and ryanodine receptor (RyR) and IP(3) receptor (IP(3)R) agonists. In untreated sister cultures each agonist distinctly increased [Ca(2+)](i), but in cultures treated for sufficient length of time or with sufficiently high doses of fluoxetine, acute administration of fluoxetine, dexmedetomidine, or RyR or IP(3)R agonists elicited reduced, in some cases abolished, effects. Capacitative Ca(2+) entry, meditated by TRPC1 channels, was sufficiently inhibited to cause a depletion of Ca(2+) stores, which could explain the reduced agonist effects. All effects of chronic fluoxetine administration could be replicated by TRPC1 channel antibody or siRNA. Since increases in astrocytic [Ca(2+)](i) regulate release of gliotransmitters, these effects may have profound effects on brain function. They may be important for therapeutic effects of all 5 conventional 'serotonin-specific reuptake inhibitors' (SSRIs), which at concentrations used therapeutically (∼1 μM) share other of fluoxetine's chronic effects (Zhang et al., Neuron Glia Biol. 16 (2010) 1-13).
Collapse
Affiliation(s)
- Baoman Li
- Department of Clinical Pharmacology, China Medical University, Shenyang, PR China
| | | | | | | | | | | |
Collapse
|
17
|
Astrocytic transactivation by α2A-adrenergic and 5-HT2B serotonergic signaling. Neurochem Int 2010; 57:421-31. [DOI: 10.1016/j.neuint.2010.04.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 03/24/2010] [Accepted: 04/28/2010] [Indexed: 12/11/2022]
|
18
|
Xu B, Zhang WS, Yang JL, Lû N, Deng XM, Xu H, Zhang YQ. Evidence for suppression of spinal glial activation by dexmedetomidine in a rat model of monoarthritis. Clin Exp Pharmacol Physiol 2010; 37:e158-66. [DOI: 10.1111/j.1440-1681.2010.05426.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
19
|
Millan MJ. From the cell to the clinic: a comparative review of the partial D₂/D₃receptor agonist and α2-adrenoceptor antagonist, piribedil, in the treatment of Parkinson's disease. Pharmacol Ther 2010; 128:229-73. [PMID: 20600305 DOI: 10.1016/j.pharmthera.2010.06.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2010] [Indexed: 12/16/2022]
Abstract
Though L-3,4-dihydroxyphenylalanine (L-DOPA) is universally employed for alleviation of motor dysfunction in Parkinson's disease (PD), it is poorly-effective against co-morbid symptoms like cognitive impairment and depression. Further, it elicits dyskinesia, its pharmacokinetics are highly variable, and efficacy wanes upon long-term administration. Accordingly, "dopaminergic agonists" are increasingly employed both as adjuncts to L-DOPA and as monotherapy. While all recognize dopamine D(2) receptors, they display contrasting patterns of interaction with other classes of monoaminergic receptor. For example, pramipexole and ropinirole are high efficacy agonists at D(2) and D(3) receptors, while pergolide recognizes D(1), D(2) and D(3) receptors and a broad suite of serotonergic receptors. Interestingly, several antiparkinson drugs display modest efficacy at D(2) receptors. Of these, piribedil displays the unique cellular signature of: 1), signal-specific partial agonist actions at dopamine D(2)and D(3) receptors; 2), antagonist properties at α(2)-adrenoceptors and 3), minimal interaction with serotonergic receptors. Dopamine-deprived striatal D(2) receptors are supersensitive in PD, so partial agonism is sufficient for relief of motor dysfunction while limiting undesirable effects due to "over-dosage" of "normosensitive" D(2) receptors elsewhere. Further, α(2)-adrenoceptor antagonism reinforces adrenergic, dopaminergic and cholinergic transmission to favourably influence motor function, cognition, mood and the integrity of dopaminergic neurones. In reviewing the above issues, the present paper focuses on the distinctive cellular, preclinical and therapeutic profile of piribedil, comparisons to pramipexole, ropinirole and pergolide, and the core triad of symptoms that characterises PD-motor dysfunction, depressed mood and cognitive impairment. The article concludes by highlighting perspectives for clarifying the mechanisms of action of piribedil and other antiparkinson agents, and for optimizing their clinical exploitation.
Collapse
Affiliation(s)
- Mark J Millan
- Dept of Psychopharmacology, Institut de Recherches Servier, 125 Chemin de Ronde, 78290 Croissy/Seine (Paris), France.
| |
Collapse
|
20
|
Sharif A, Prevot V. ErbB receptor signaling in astrocytes: a mediator of neuron-glia communication in the mature central nervous system. Neurochem Int 2010; 57:344-58. [PMID: 20685225 DOI: 10.1016/j.neuint.2010.05.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 03/29/2010] [Accepted: 05/18/2010] [Indexed: 10/19/2022]
Abstract
Astrocytes are now recognized as active players in the developing and mature central nervous system. Each astrocyte contacts vascular structures and thousands of synapses within discrete territories. These cells receive a myriad of inputs and generate appropriate responses to regulate the function of brain microdomains. Emerging evidence has implicated receptors of the ErbB tyrosine kinase family in the integration and processing of neuronal inputs by astrocytes: ErbB receptors can be activated by a wide range of neuronal stimuli; they control critical steps of glutamate-glutamine metabolism; and they regulate the biosynthesis and release of various glial-derived neurotrophic factors, gliomediators and gliotransmitters. These key properties of astrocytic ErbB signaling in neuron-glia interactions have significance for the physiology of the mature central nervous system, as exemplified by the central control of reproduction within the hypothalamus, and are also likely to contribute to pathological situations, since both dysregulation of ErbB signaling and glial dysfunction occur in many neurological disorders.
Collapse
Affiliation(s)
- Ariane Sharif
- Inserm, Jean-Pierre Aubert Research Center, U837, Development and Plasticity of the postnatal Brain, Lille, France.
| | | |
Collapse
|
21
|
Li B, Zhang S, Li M, Hertz L, Peng L. Serotonin increases ERK1/2 phosphorylation in astrocytes by stimulation of 5-HT2B and 5-HT2C receptors. Neurochem Int 2010; 57:432-9. [PMID: 20450948 DOI: 10.1016/j.neuint.2010.04.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 03/24/2010] [Accepted: 04/26/2010] [Indexed: 11/29/2022]
Abstract
We have previously shown that fluoxetine causes ERK(1/2) phosphorylation in cultured mouse astrocytes mediated exclusively by stimulation of 5-HT(2B) receptors (Li et al., 2008b). This raises the question whether this is also the case for serotonin (5-HT) itself. In the present study serotonin was found to induce ERK(1/2) phosphorylation by stimulation of 5-HT(2B) receptors with high affinity (EC(50): 20-30 pM), and by stimulation of 5-HT(2C) receptor with low affinity (EC(50): 1 microM or higher). ERK(1/2) phosphorylation induced by stimulation of either 5-HT(2B) or 5-HT(2C) receptors was mediated by epidermal growth factor (EGF) receptor transactivation (Peng et al., this issue), shown by the inhibitory effect of AG1478, an inhibitor of the EGF receptor tyrosine kinase, and GM6001, an inhibitor of Zn-dependent metalloproteinases, and thus of 5-HT(2B) receptor-mediated EGF receptor agonist release. It is discussed that the high potency of the 5-HT(2B)-mediated effect is consistent with literature data for binding affinity of serotonin to cloned human 5-HT(2B) receptors and with observations of low extracellular concentrations of serotonin in brain, which would allow a demonstrated moderate and modality-dependent increase in specific brain areas to activate 5-HT(2B) receptors. In contrast the relevance of the observed 5-HT(2C) receptors on astrocytes is questioned.
Collapse
Affiliation(s)
- Baoman Li
- Department of Clinical Pharmacology, China Medical University, Heping District, Shenyang, PR China
| | | | | | | | | |
Collapse
|
22
|
Xue Z, Li B, Gu L, Hu X, Li M, Butterworth RF, Peng L. Increased Na, K-ATPase alpha2 isoform gene expression by ammonia in astrocytes and in brain in vivo. Neurochem Int 2010; 57:395-403. [PMID: 20447429 DOI: 10.1016/j.neuint.2010.04.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 03/28/2010] [Accepted: 04/27/2010] [Indexed: 10/19/2022]
Abstract
In mouse astrocyte cultures identical to those used in the present study ammonia increases the production of ouabain-like compounds and Na, K-ATPase activity (Kala et al., 2000). Increased activity of Na, K-ATPase could be the result of enhanced production of ouabain-like compounds, since cultured rat astrocytes react to prolonged exposure to a high concentration of ouabain with an upregulation of the Na, K-ATPase alpha(1) isoform (Hosoi et al., 1997). However, unlike astrocytes in brain in vivo and mouse primary cultures, cultured rat astrocytes do not express the astrocyte-specific alpha(2) isoform, which shows a higher affinity for ouabain (EC(50) approximately 0.1 microM) than the alpha(1) isoform (EC(50) approximately 10 microM). In the present study we have investigated (i) effects of ammonia on mRNA and protein expression of alpha(1) and alpha(2) isoforms in primary cultures of mouse astrocytes; (ii) effects of hyperammonia obtained by urease injection on mRNA and protein expression of alpha(1) and alpha(2) isoforms in the brain in vivo; and (iii) effect on observed upregulation of gene expression of AG1478, an inhibitor of the EGF receptor-tyrosine kinase, PP1, an inhibitor of Src, and GM6001, an inhibitor of Zn(2+)-dependent metalloproteinases in the cultured cells. It was established that alpha(2) mRNA and protein expression, but not alpha(1) expression, was upregulated in cultured astrocytes by 1-4 days of exposure to 3 or 5 mM ammonia and that similar upregulation, contrasted by a downregulation of the neuronal alpha(3) subunit occurred in the hyperammonemic brain. Based on the effects of the inhibitors and literature data it is concluded that ammonia activates formation of an endogenous ouabain-like compound, which binds to the Na, K-ATPase, activating Src, which in turn stimulates the receptor-tyrosine kinase of the EGF receptor, leading to activation of the Ras, Raf, MEK pathway and phosphorylation of ERK(1/2), which eventually causes upregulation of alpha(2) gene expression.
Collapse
Affiliation(s)
- Zhanxia Xue
- Department of Clinical Pharmacology, China Medical University, Shenyang, PR China
| | | | | | | | | | | | | |
Collapse
|
23
|
ERK phosphorylation in intact, adult brain by α2-adrenergic transactivation of EGF receptors. Neurochem Int 2009; 55:593-600. [DOI: 10.1016/j.neuint.2009.05.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 05/27/2009] [Accepted: 05/28/2009] [Indexed: 11/23/2022]
|
24
|
Xu ZY, Liu HD, Lau LT, Yingge Z, Zhao R, Tong GL, Chan PH, Yu ACH. Responses of astrocyte to simultaneous glutamate and arachidonic acid treatment. Neurochem Int 2009; 55:143-50. [DOI: 10.1016/j.neuint.2009.02.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 02/17/2009] [Accepted: 02/25/2009] [Indexed: 10/21/2022]
|
25
|
Du T, Song D, Li H, Li B, Cai L, Hertz L, Peng L. Stimulation by vasopressin of ERK phosphorylation and vector-driven water flux in astrocytes is transactivation-dependent. Eur J Pharmacol 2008; 587:73-7. [DOI: 10.1016/j.ejphar.2008.03.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 03/03/2008] [Accepted: 03/14/2008] [Indexed: 11/16/2022]
|
26
|
Li B, Du T, Li H, Gu L, Zhang H, Huang J, Hertz L, Peng L. Signalling pathways for transactivation by dexmedetomidine of epidermal growth factor receptors in astrocytes and its paracrine effect on neurons. Br J Pharmacol 2008; 154:191-203. [PMID: 18311185 DOI: 10.1038/bjp.2008.58] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Stimulation of astrocytes by the alpha(2)-adrenoceptor agonist dexmedetomidine, a neuroprotective drug, transactivates epidermal growth factor (EGF) receptors. The present study investigates signal pathways leading to release of an EGF receptor ligand and those activated during EGF receptor stimulation, and the response of neurons to dexmedetomidine and to astrocyte-conditioned medium. EXPERIMENTAL APPROACH Phosphorylation of ERK(1/2) was determined by western blotting and immunocytochemistry, and phosphorylation of EGF receptors by immunoprecipitation and western blotting. mRNA expression of fos family was measured by RT-PCR. KEY RESULTS Pertussis toxin (0.2 microg ml(-1)) an inhibitor of betagamma subunit dissociation from Galpha(i) protein, and GF 109203X (500 nM), a protein kinase C inhibitor, abolished ERK(1/2) phosphorylation. PP1 (10 microM), inhibiting Src kinase and GM 6001 (10 microM), an inhibitor of Zn-dependent metalloproteinase, abolished ERK(1/2) phosphorylation by dexmedetomidine (50 nM), but not that by EGF (10 ng ml(-1)), showing Src kinase and metalloproteinase activation during the first stage only; AG 1478 (1 microM), an inhibitor of the EGF receptor tyrosine kinase, abolished ERK(1/2) phosphorylation. Dexmedetomidine-induced EGF receptor phosphorylation was prevented by AG 1478, GM 6001, PP1 and GF 109203X and its induction of cfos and fosB by AG 1478 and by U0126 (10 microM), an inhibitor of ERK phosphorylation, indicating downstream effects of ERK(1/2) phosphorylation. EGF and conditioned medium from dexmedetomidine-treated astrocytes, but not dexmedetomidine itself, induced ERK phosphorylation in primary cultures of cerebellar neurons. CONCLUSIONS AND IMPLICATIONS Dexmedetomidine-induced transactivation pathways were delineated. Its paracrine effect on neurons may account for its neuroprotective effects.
Collapse
Affiliation(s)
- B Li
- Department of Clinical Pharmacology, China Medical University, Shenyang, PR China
| | | | | | | | | | | | | | | |
Collapse
|
27
|
Buffin-Meyer B, Crassous PA, Delage C, Denis C, Schaak S, Paris H. EGF receptor transactivation and PI3-kinase mediate stimulation of ERK by alpha(2A)-adrenoreceptor in intestinal epithelial cells: a role in wound healing. Eur J Pharmacol 2007; 574:85-93. [PMID: 17655843 DOI: 10.1016/j.ejphar.2007.07.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 07/02/2007] [Accepted: 07/05/2007] [Indexed: 12/11/2022]
Abstract
Intestinal cells express alpha(2A)-adrenoreceptors that stimulate sodium and peptide absorption and promote cell proliferation. Involved mechanisms are poorly understood and are not fully related to inhibition of cAMP production. Previous study using a clone of CaCo2 cells expressing the human alpha(2A)-adrenoreceptor (CaCo2-3B) showed that alpha(2)-adrenoreceptor agonists cause extracellular signal-regulated kinase (ERK) phosphorylation. Present work examines the signaling pathway triggering ERK activation and investigates the consequence of alpha(2A)-adrenoreceptor stimulation on cell migration. Treatment of CaCo2-3B with the alpha(2)-adrenoreceptor agonist 5-bromo-6-(2-imidazolin-2-ylamino) quinoxaline (UK14304) induces not only ERK, but also Akt phosphorylation. Both effects are strongly attenuated by inhibition or desensitization of epidermal growth factor (EGF) receptor, matrix metalloproteinase (MMP) blockade, heparin-binding-EGF neutralization or phosphatidylinositol 3-kinase (PI3-kinase) inhibitors. Conditioned medium from UK14304-treated CaCo2-3B stimulates ERK in parental CaCo2 by a mechanism sensitive to EGF receptor and PI3-kinase inhibitors. Exposure of CaCo2-3B to UK14304 accelerates the wound healing. This effect is abolished by heparin-binding-EGF neutralization but not by mitomycin C, indicating that it results probably from increased cell spreading and/or migration. In conclusion, alpha(2A)-adrenoreceptor activates ERK and Akt in intestinal cells by a common pathway which depends on PI3-kinase activation and results from EGF receptor transactivation, via an autocrine/paracrine pathway implying MMP activation and heparin-binding-EGF shedding. Therefore, alpha(2A)-adrenoreceptor could have a positive role in intestinal regeneration in vivo.
Collapse
Affiliation(s)
- Bénédicte Buffin-Meyer
- INSERM, U858/I2MR, Department of Renal and Cardiac remodelling, team #5, 1 avenue Jean Poulhès, BP 84225, 31432 Toulouse Cedex 4, France.
| | | | | | | | | | | |
Collapse
|