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Liu P, Yang X, Niu J, Hei C. Hyperglycemia aggravates ischemic brain damage via ERK1/2 activated cell autophagy and mitochondrial fission. Front Endocrinol (Lausanne) 2022; 13:928591. [PMID: 35992111 PMCID: PMC9388937 DOI: 10.3389/fendo.2022.928591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 07/11/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Hyperglycemia is one of the major risk factors for stroke and stroke recurrence, leading to aggravated neuronal damage after cerebral ischemia/reperfusion (I/R). ERK1/2 signaling pathway plays a vital role in cerebral ischemic injury. However, the role of the ERK1/2 pathway in hyperglycemia-aggravated ischemic brain damage is not clear. METHODS Streptozotocin (STZ; 50 mg/kg)-induced diabetes (blood glucose ≥12 mmol/L) or control groups in adult Sprague-Dawley rats were further subdivided into I/R (carotid artery/vein clamping), I/R + PD98059 (I/R plus ERK1/2 inhibitor), and Sham-operated groups (n = 10 each). Neurobehavioral status (Neurological behavior scores) and the volume of the cerebral infarction (TTC staining); brain mitochondrial potential (JCI ratio test) and cell apoptosis (TUNEL assay); RAS protein expression, phosphorylated/total ERK1/2 and Drp-1 (Dynamic-related protein 1) protein levels (Western blotting); mitochondrial fusion-related proteins mitofusin-1/2 (Mfn1/2), optic atrophy (OPA-1) and mitochondrial fission 1 (Fis1), and autophagy-associated proteins Beclin-1, LC3-I/II and P62 (Western blotting and immunohistochemistry) were analyzed. RESULTS The I/R + PD98059 group demonstrated better neurobehavior on the 1st (p < 0.05) and the 3rd day (p < 0.01) than the I/R group. Compared to the Sham group, cerebral ischemia/reperfusion brought about neuronal damage in the I/R group (p <0.01). However, treatment with PD98059 showed an improved situation with faster recovery of mitochondrial potential and less apoptosis of neuronal cells in the I/R + PD98059 group (p < 0.01). The I/R group had a higher-level expression of RAS and phosphorylated ERK1/2 and Drp-1 than the diabetes mellitus (DM) group (p < 0.01). The PD98059 treated group showed decreased expression of p-ERK1/2, p-Drp-1, Fis1, and Beclin-1, LC3-I/II and P62, but increased Mfn1/2 and OPA-1 than the I/R group (p < 0.01). CONCLUSION Hyperglycemia worsens cerebral ischemia/reperfusion-induced neuronal damage via ERK1/2 activated cell autophagy and mitochondrial fission.
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Affiliation(s)
- Ping Liu
- Department of Endocrinology, General Hospital of Ningxia Medical University, Yinchuan, China
| | - Xiao Yang
- Neuroscience Center, General Hospital of Ningxia Medical University, Yinchuan, China
| | - Jianguo Niu
- Ningxia Key Laboratory of Cerebrocranial Disease, Ningxia Medical University, Yinchuan, China
| | - Changchun Hei
- Ningxia Key Laboratory of Cerebrocranial Disease, Ningxia Medical University, Yinchuan, China
- Department of Human Anatomy, Histology and Embryology, Ningxia Medical University, Yinchuan, China
- *Correspondence: Changchun Hei,
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Hu MH, Wu CT, Hsia SH, Hung PC, Huang GS. Clinical Features and Risk Factors for Mortality in Children With Acute Encephalitis Who Present to the Emergency Department. J Child Neurol 2020; 35:724-730. [PMID: 32507002 DOI: 10.1177/0883073820930557] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Acute encephalitis is an important pediatric emergency that tends to be associated with neurological morbidity, critical illness, and mortality. Few data have specifically focused on evaluating various early clinical parameters in the pediatric emergency department as candidate predictors of mortality. The present retrospective study assessed the clinical, laboratory, and neuroimaging findings of children with acute encephalitis who presented to the emergency department. Of 158 patients diagnosed with encephalitis, 7 (4.4%) had mortality. Compared to the survivors, a multivariate analysis revealed that an initial Glasgow Coma Scale score ≤ 5 (odds ratio [OR]: 8.3, P = .022), acute necrotizing encephalitis (OR: 12.1, P = .01), white blood count level ≤ 5.2 × 109 cells/L (OR: 28.7, P < .001), aspartate aminotransferase level > 35 U/L (OR: 14.3, P = .022), and influenza A infection (OR: 7.7, P = .027) were significantly associated with mortality. These results indicate that the early recognition of preliminary clinical features and the development of more specific etiologies for encephalitis are important for early treatment strategies.
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Affiliation(s)
- Mei-Hua Hu
- Division of Pediatric General Medicine, Department of Pediatrics, 38014Chang Gung Memorial Hospital, LinKou Branch, College of Medicine, Chang Gung University, Taoyuan, Taiwan.,Graduate Institute of Clinical Medical Sciences, College of Medicine, 56081Chang Gung University, Taoyuan, Taiwan.,School of Chinese Medicine, College of Medicine, 56081Chang Gung University, Taoyuan, Taiwan
| | - Chang-Teng Wu
- Division of Pediatric General Medicine, Department of Pediatrics, 38014Chang Gung Memorial Hospital, LinKou Branch, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Shao-Hsuan Hsia
- Division of Pediatric Critical Care Medicine, Department of Pediatrics, 38014Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan
| | - Po-Cheng Hung
- Division of Pediatric Neurology, Department of Pediatrics, 38014Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan
| | - Go-Shine Huang
- Department of Anesthesiology, Tri-Service General Hospital, 71548National Defense Medical Center, Taipei, Taiwan
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Yang X, Hei C, Liu P, Li PA. Prevention of post-ischemic seizure by rapamycin is associated with deactivation of mTOR and ERK1/2 pathways in hyperglycemic rats. Biochem Biophys Res Commun 2019; 520:47-53. [PMID: 31564412 DOI: 10.1016/j.bbrc.2019.09.096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 09/22/2019] [Indexed: 12/11/2022]
Abstract
Pre-ischemic hyperglycemia increases the occurrence of post-ischemic seizures both in experimental and clinical settings. The underlying mechanisms are not fully delineated; however, activation of mammalian target of rapamycin (mTOR) has been shown to be engaged in the pathogenesis of epilepsy, in which seizures are a regular occurrence. Therefore, we wanted to explore specifically the capacity of an mTOR inhibitor, rapamycin, in preventing post-ischemic seizures in hyperglycemic rats and to explore the underlying molecular mechanisms. The results showed that none of the rats in the sham control, EG ischemic, or within 3 h of I/R in hyperglycemic ischemic groups experienced seizures. Generalized tonic-clonic seizures were observed in all 8/8 of hyperglycemic ischemic rats at 16 h of I/R. Treatment with rapamycin successfully blocked post-ischemic seizures in 7/8 hyperglycemic ischemic animals. Rapamycin also lessened the neuronal death extraordinarily in hyperglycemic ischemic animals as revealed by histopathological studies. Protein analysis revealed that transient ischemia resulted in increases in p-mTOR and p-S6, especially in the hippocampi of the hyperglycemic ischemic rats. Rapamycin treatment completely blocked mTOR activation. Furthermore, hyperglycemic ischemia induced a much prominent rise of p-ERK1/2 both in the cortex and the hippocampi compared with EG counterparts; whereas rapamycin suppressed it. We conclude that the development of post-ischemic seizures in the hyperglycemic animals may be associated with activations of mTOR and ERK1/2 pathways and that rapamycin treatment inhibited the post-ischemic seizures effectively by suppressing the mTOR and ERK1/2 signaling.
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Affiliation(s)
- Xiao Yang
- Neuroscience Center, General Hospital of Ningxia Medical University, Key Laboratory for Craniocerebral Diseases of Ningxia Hui Autonomous Region, Yinchuan, China; Department of Pharmaceutical Sciences, Biomanufacturing Research Institute Technology Enterprise (BRITE), College of Arts and Sciences, North Carolina Central University, Durham, USA
| | - Changchun Hei
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute Technology Enterprise (BRITE), College of Arts and Sciences, North Carolina Central University, Durham, USA; Department of Human Anatomy, Histology and Embryology, Ningxia Medical University, Yinchuan, China
| | - Ping Liu
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute Technology Enterprise (BRITE), College of Arts and Sciences, North Carolina Central University, Durham, USA; Department of Endocrinology, General Hospital of Ningxia Medical University, Yinchuan, China
| | - P Andy Li
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute Technology Enterprise (BRITE), College of Arts and Sciences, North Carolina Central University, Durham, USA.
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Li C, Che LH, Ji TF, Shi L, Yu JL. Effects of the TLR4 signaling pathway on apoptosis of neuronal cells in diabetes mellitus complicated with cerebral infarction in a rat model. Sci Rep 2017; 7:43834. [PMID: 28272417 PMCID: PMC5341048 DOI: 10.1038/srep43834] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 01/31/2017] [Indexed: 12/13/2022] Open
Abstract
This study aims to explore the effects of the TLR4 signaling pathway on the apoptosis of neuronal cells in rats with diabetes mellitus complicated with cerebral infarction (DMCI). A DMCI model was established with 40 Sprague Dawley rats, which were assigned into blank, sham, DM + middle cerebral artery occlusion (MCAO) and DM + MCAO + TAK242 groups. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were measured. A TUNEL assay was applied for detecting cell apoptosis, and Western blotting was used for detecting the expression of TLR4, TNF-α, IL-1β and apoptosis-related proteins. Compared with the blank and sham groups, there was an increase in cell apoptosis, expression of Bcl-2, Bax, cleaved caspase-3, TNF-α, IL-1β and TLR4 proteins and MDA content and a decrease in SOD activity in the DM + MCAO and DM + MCAO + TAK242 groups. Compared with those in the DM + MCAO group, rats in the DM + MCAO + TAK242 group exhibited an increase in SOD activity and a decrease in cell apoptosis, expression of Bcl-2, Bax, cleaved caspase-3, TNF-α, IL-1β and TLR4 proteins and MDA content. Inhibition of the TLR4 signaling pathway reduces neuronal cell apoptosis and nerve injury to protect the brain.
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Affiliation(s)
- Chao Li
- Department of Neurology, The First Hospital of Jilin University, Changchun 130021, P.R. China
| | - Li-He Che
- Department of Infectious Diseases, The First Hospital of Jilin University, Changchun 130021, P.R. China
| | - Tie-Feng Ji
- Department of Radiology, The First Hospital of Jilin University, Changchun 130021, P.R. China
| | - Lei Shi
- Department of Neurosurgery, The First Hospital of Jilin University, Changchun 130021, P.R. China
| | - Jin-Lu Yu
- Department of Neurosurgery, The First Hospital of Jilin University, Changchun 130021, P.R. China
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Lan X, Zhang X, Zhou GP, Wu CX, Li C, Xu XH. Electroacupuncture reduces apoptotic index and inhibits p38 mitogen-activated protein kinase signaling pathway in the hippocampus of rats with cerebral ischemia/reperfusion injury. Neural Regen Res 2017; 12:409-416. [PMID: 28469655 PMCID: PMC5399718 DOI: 10.4103/1673-5374.202944] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Electroacupuncture attenuates cerebral hypoxia and neuronal apoptosis induced by cerebral ischemia/reperfusion injury. To further identify the involved mechanisms, we assumed that electroacupuncture used to treat cerebral ischemia/reperfusion injury was associated with the p38 mitogen-activated protein kinase (MAPK) signaling pathway. We established rat models of cerebral ischemia/reperfusion injury using the modified Zea-Longa's method. At 30 minutes before model establishment, p38 MAPK blocker SB20358 was injected into the left lateral ventricles. At 1.5 hours after model establishment, electroacupuncture was administered at acupoints of Chize (LU5), Hegu (LI4), Zusanli (ST36), and Sanyinjiao (SP6) for 20 minutes in the affected side. Results showed that the combination of EA and SB20358 injection significantly decreased neurologic impairment scores, but no significant differences were determined among different interventional groups. Hematoxylin-eosin staining also showed reduced brain tissue injuries. Compared with the SB20358 group, the cells were regularly arranged, the structures were complete, and the number of viable neurons was higher in the SB20358 + electroacupuncture group. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling assay showed a decreased apoptotic index in each group, with a significant decrease in the SB20358 + electroacupuncture group. Immunohistochemistry revealed reduced phosphorylated p38 expression at 3 days in the electroacupuncture group and SB20358 + electroacupuncture group compared with the ischemia/reperfusion group. There was no significant difference in phosphorylated p38 expression between the ischemia/reperfusion group and SB20358 group. These findings confirmed that the electroacupuncture effects on mitigating cerebral ischemia/reperfusion injury are possibly associated with the p38 MAPK signaling pathway. A time period of 3 days could promote the repair of ischemic cerebral nerves.
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Affiliation(s)
- Xiao Lan
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Xin Zhang
- College of Acupuncture, Moxibustion and Tuina, Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Guo-Ping Zhou
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Chun-Xiao Wu
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Chun Li
- College of Acupuncture, Moxibustion and Tuina, Hunan University of Chinese Medicine, Changsha, Hunan Province, China
| | - Xiu-Hong Xu
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, Guangdong Province, China
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Liu P, Yang X, Hei C, Meli Y, Niu J, Sun T, Li PA. Rapamycin Reduced Ischemic Brain Damage in Diabetic Animals Is Associated with Suppressions of mTOR and ERK1/2 Signaling. Int J Biol Sci 2016; 12:1032-40. [PMID: 27489506 PMCID: PMC4971741 DOI: 10.7150/ijbs.15624] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/28/2016] [Indexed: 12/17/2022] Open
Abstract
The objectives of the present study are to investigate the activation of mTOR and ERK1/2 signaling after cerebral ischemia in diabetic rats and to examine the neuroprotective effects of rapamycin. Ten minutes transient global cerebral ischemia was induced in straptozotocin-induced diabetic hyperglycemic rats and non-diabetic, euglycemic rats. Brain samples were harvested after 16 h of reperfusion. Rapamycin or vehicle was injected 1 month prior to the induction of ischemia. The results showed that diabetes increased ischemic neuronal cell death and associated with elevations of p-P70S6K and Ras/ERK1/2 and suppression of p-AMPKα. Rapamycin ameliorated diabetes-enhanced ischemic brain damage and suppressed phosphorylation of P70S6K and ERK1/2. It is concluded that diabetes activates mTOR and ERK1/2 signaling pathways in rats subjected to transient cerebral ischemia and inhibition of mTOR by rapamycin reduces ischemic brain damage and suppresses the mTOR and ERK1/2 signaling in diabetic settings.
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Affiliation(s)
- Ping Liu
- 1. Department of Endocrinology, General Hospital of Ningxia Medical University, Yinchuan 750004, China
- 2. Department of Pharmaceutical Sciences, Biomanufacturing Research Institute Biotechnology Enterprise (BRITE), North Carolina Central University, 1801 Fayetteville Street, Durham, NC 27707, USA
| | - Xiao Yang
- 2. Department of Pharmaceutical Sciences, Biomanufacturing Research Institute Biotechnology Enterprise (BRITE), North Carolina Central University, 1801 Fayetteville Street, Durham, NC 27707, USA
- 3. Neuroscience Center, General Hospital of Ningcia Medical University, and Key Laboratory of Craniocerebral Diseases of Ningxia Hui Autonomous Region, Yinchuan 750004, China
| | - Changchun Hei
- 2. Department of Pharmaceutical Sciences, Biomanufacturing Research Institute Biotechnology Enterprise (BRITE), North Carolina Central University, 1801 Fayetteville Street, Durham, NC 27707, USA
- 4. Department of Human Anatomy, Histology and Embryology, Ningxia Medical University, Yinchuan 75004, China
| | - Yvonne Meli
- 2. Department of Pharmaceutical Sciences, Biomanufacturing Research Institute Biotechnology Enterprise (BRITE), North Carolina Central University, 1801 Fayetteville Street, Durham, NC 27707, USA
| | - Jianguo Niu
- 4. Department of Human Anatomy, Histology and Embryology, Ningxia Medical University, Yinchuan 75004, China
| | - Tao Sun
- 4. Department of Human Anatomy, Histology and Embryology, Ningxia Medical University, Yinchuan 75004, China
| | - P. Andy Li
- 2. Department of Pharmaceutical Sciences, Biomanufacturing Research Institute Biotechnology Enterprise (BRITE), North Carolina Central University, 1801 Fayetteville Street, Durham, NC 27707, USA
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Du LL, Xie JZ, Cheng XS, Li XH, Kong FL, Jiang X, Ma ZW, Wang JZ, Chen C, Zhou XW. Activation of sirtuin 1 attenuates cerebral ventricular streptozotocin-induced tau hyperphosphorylation and cognitive injuries in rat hippocampi. AGE (DORDRECHT, NETHERLANDS) 2014; 36:613-623. [PMID: 24142524 PMCID: PMC4039268 DOI: 10.1007/s11357-013-9592-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 10/07/2013] [Indexed: 06/02/2023]
Abstract
Patients with diabetes in the aging population are at high risk of Alzheimer's disease (AD), and reduction of sirtuin 1 (SIRT1) activity occurs simultaneously with the accumulation of hyperphosphorylated tau in the AD-affected brain. It is not clear, however, whether SIRT1 is a suitable molecular target for the treatment of AD. Here, we employed a rat model of brain insulin resistance with intracerebroventricular injection of streptozotocin (ICV-STZ; 3 mg/kg, twice with an interval of 48 h). The ICV-STZ-treated rats were administrated with resveratrol (RSV; SIRT1-specific activator) or a vehicle via intraperitoneal injection for 8 weeks (30 mg/kg, once per day). In ICV-STZ-treated rats, the levels of phosphorylated tau and phosphorylated extracellular signal-regulated kinases 1 and 2 (ERK1/2) at the hippocampi were increased significantly, whereas SIRT1 activity was decreased without change of its expression level. The capacity of spatial memory was also significantly lower in ICV-STZ-treated rats compared with age-matched control. RSV, a specific activator of SIRT1, which reversed the ICV-STZ-induced decrease in SIRT1 activity, increases in ERK1/2 phosphorylation, tau phosphorylation, and impairment of cognitive capability in rats. In conclusion, SIRT1 protects hippocampus neurons from tau hyperphosphorylation and prevents cognitive impairment induced by ICV-STZ brain insulin resistance with decreased hippocampus ERK1/2 activity.
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Affiliation(s)
- Lai-Ling Du
- />Department of Pathophysiology, Key Laboratory of Neurological Diseases of Education Ministry of China, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Jia-Zhao Xie
- />Department of Pathophysiology, Key Laboratory of Neurological Diseases of Education Ministry of China, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Xiang-Shu Cheng
- />Department of Pathophysiology, Key Laboratory of Neurological Diseases of Education Ministry of China, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Xiao-Hong Li
- />Department of Pathophysiology, Key Laboratory of Neurological Diseases of Education Ministry of China, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Fan-Li Kong
- />Department of Pathophysiology, Key Laboratory of Neurological Diseases of Education Ministry of China, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Xia Jiang
- />Department of Pathophysiology, Key Laboratory of Neurological Diseases of Education Ministry of China, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Zhi-Wei Ma
- />Department of Pathophysiology, Key Laboratory of Neurological Diseases of Education Ministry of China, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Jian-Zhi Wang
- />Department of Pathophysiology, Key Laboratory of Neurological Diseases of Education Ministry of China, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Chen Chen
- />School of Biomedical Sciences, University of Queensland, Brisbane, QLD 4072 Australia
| | - Xin-Wen Zhou
- />Department of Pathophysiology, Key Laboratory of Neurological Diseases of Education Ministry of China, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
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Yuen N, Lam TI, Wallace BK, Klug NR, Anderson SE, O'Donnell ME. Ischemic factor-induced increases in cerebral microvascular endothelial cell Na/H exchange activity and abundance: evidence for involvement of ERK1/2 MAP kinase. Am J Physiol Cell Physiol 2014; 306:C931-42. [PMID: 24647544 DOI: 10.1152/ajpcell.00021.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Brain edema forms rapidly in the early hours of ischemic stroke by increased secretion of Na, Cl, and water into the brain across an intact blood-brain barrier (BBB), together with swelling of astrocytes as they take up the ions and water crossing the BBB. Our previous studies provide evidence that luminal BBB Na-K-Cl cotransport (NKCC) and Na/H exchange (NHE) participate in ischemia-induced edema formation. NKCC1 and two NHE isoforms, NHE1 and NHE2, reside predominantly at the luminal BBB membrane. NKCC and NHE activities of cerebral microvascular endothelial cells (CMEC) are rapidly stimulated by the ischemic factors hypoxia, aglycemia, and AVP, and inhibition of NKCC and NHE activities by bumetanide and HOE642, respectively, reduces brain Na uptake and edema in the rat middle cerebral artery occlusion model of stroke. The present study was conducted to further explore BBB NHE responses to ischemia. We examined whether ischemic factor-stimulated NHE activity is sustained over several hours, when the majority of edema forms during stroke. We also examined whether ischemic factors alter NHE1 and/or NHE2 protein abundance. Finally, we conducted initial studies of ERK1/2 MAP kinase involvement in BBB NHE and NKCC responses to ischemic factors. We found that hypoxia, aglycemia, and AVP increase CMEC NHE activity through 5 h and that NHE1, but not NHE2, abundance is increased by 1- to 5-h exposures to these factors. Furthermore, we found that these factors rapidly increase BBB ERK1/2 activity and that ERK1/2 inhibition reduces or abolishes ischemic factor stimulation of NKCC and NHE activities.
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Affiliation(s)
- Natalie Yuen
- Department of Physiology and Membrane Biology, University of California, Davis, California
| | - Tina I Lam
- Department of Physiology and Membrane Biology, University of California, Davis, California
| | - Breanna K Wallace
- Department of Physiology and Membrane Biology, University of California, Davis, California
| | - Nicholas R Klug
- Department of Physiology and Membrane Biology, University of California, Davis, California
| | - Steven E Anderson
- Department of Physiology and Membrane Biology, University of California, Davis, California
| | - Martha E O'Donnell
- Department of Physiology and Membrane Biology, University of California, Davis, California
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Zhang JZ, Jing L, Ma Y, Guo FY, Chang Y, Li PA. Monosialotetrahexosy-1 ganglioside attenuates diabetes-enhanced brain damage after transient forebrain ischemia and suppresses phosphorylation of ERK1/2 in the rat brain. Brain Res 2010; 1344:200-8. [PMID: 20546707 DOI: 10.1016/j.brainres.2010.05.044] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 05/11/2010] [Accepted: 05/12/2010] [Indexed: 11/19/2022]
Abstract
Monosialotetrahexosy-1 ganglioside (GM1) has been shown to reduce brain damage induced by cerebral ischemia. The objective of this study is to determine whether GM1 is able to ameliorate hyperglycemia-exacerbated ischemic brain damage in hyperglycemia-recruited areas such as the hippocampal CA3 sub regions and the cingulated cortex. Histologic stainings of Haematoxylin and Eosin, Nissl body, the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) and phospho-ERK1/2 were performed on brain sections that have been subjected to 15 min of forebrain ischemia with reperfusion of 0, 1, 3, and 6h in normoglycemic, hyperglycemic and GM1-pretreated hyperglycemic groups. The results showed that GM1 ameliorated ischemic neuronal injuries in the CA3 area and cingulated cortex of the hyperglycemic animals after ischemia and reperfusion. Immunohistochemistry of phospho-ERK1/2 revealed that the neuroprotective effects of GM1 were associated with suppression of phospho-ERK1/2. The results suggest that GM1 attenuates diabetic-augmented ischemic neuronal injuries probably through suppression of ERK1/2 phosphorylation.
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Affiliation(s)
- Jian-Zhong Zhang
- Department of Pathology, Ningxia Medical University, Yinchuan 750004, PR China.
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Farrokhnia N, Ericsson A, Terént A, Lennmyr F. MEK-inhibitor U0126 in hyperglycaemic focal ischaemic brain injury in the rat. Eur J Clin Invest 2008; 38:679-85. [PMID: 18837745 DOI: 10.1111/j.1365-2362.2008.01990.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Hyperglycaemia aggravates ischaemic brain injury, possibly due to activation of signalling pathways involving mitogen-activated protein kinases (MAPK). In this study, the activation of MAPK/ERK was inhibited using the upstream inhibitor of MAPK-ERK-kinase (MEK) U0126, and the effects on focal brain ischaemia were evaluated during normo- and hyperglycaemia. MATERIALS AND METHODS Temporary (90 min) middle cerebral artery occlusion (MCAO) was induced in five groups of rats. U0126 (400 microg kg(-1)) or vehicle was given as 60-min intravenous infusions starting either 30 min prior to MCAO or 30 min prior to reperfusion. The infarct size was determined by perfusion with tetrazolium red after 24 h of survival, and the neurology was tested with the 4-level scale of Bederson and performance on an inclined plane. The inhibitory effect on the targeted MEK enzyme was investigated by analysing the phosphorylation of the downstream target ERK with western immunoblotting. Two subgroups were investigated with magnetic resonance imaging (MRI), including diffusion-weighted (DWI) and perfusion-weighted imaging (PWI). RESULTS U0126 effectively reduced the infarct size and improved neurology in hyperglycaemic rats both when given before and after ischemic onset. This effect was not accompanied by any detectable changes in cerebral blood flow on MRI. Normoglycaemic rats had generally milder injuries compared with the hyperglycaemic and there was a nonsignificant trend for U0126 to reduce damage also in the nonhyperglycaemic groups. CONCLUSIONS In conclusion, U0126 appears to be neuroprotective in this model of hyperglycaemic ischaemic brain injury. The findings support the pathogenic importance of the MEK-ERK pathway in hyperglycaemic-ischaemic brain injury.
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Affiliation(s)
- N Farrokhnia
- Department of Medical Sciences, Uppsala University Hospital, Uppsala, Sweden.
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Sawe N, Steinberg G, Zhao H. Dual roles of the MAPK/ERK1/2 cell signaling pathway after stroke. J Neurosci Res 2008; 86:1659-69. [DOI: 10.1002/jnr.21604] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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