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Repression of the Glucocorticoid Receptor Aggravates Acute Ischemic Brain Injuries in Adult Mice. Int J Mol Sci 2018; 19:ijms19082428. [PMID: 30126083 PMCID: PMC6121696 DOI: 10.3390/ijms19082428] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 08/09/2018] [Accepted: 08/15/2018] [Indexed: 12/20/2022] Open
Abstract
Strokes are one of the leading causes of mortality and chronic morbidity in the world, yet with only limited successful interventions available at present. Our previous studies revealed the potential role of the glucocorticoid receptor (GR) in the pathogenesis of neonatal hypoxic-ischemic encephalopathy (HIE). In the present study, we investigate the effect of GR knockdown on acute ischemic brain injuries in a model of focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO) in adult male CD1 mice. GR siRNAs and the negative control were administered via intracerebroventricular (i.c.v.) injection 48 h prior to MCAO. The cerebral infarction volume and neurobehavioral deficits were determined 48 h after MCAO. RT-qPCR was employed to assess the inflammation-related gene expression profiles in the brain before and after MCAO. Western Blotting was used to evaluate the expression levels of GR, the mineralocorticoid receptor (MR) and the brain-derived neurotrophic factor/tropomyosin receptor kinase B (BDNF/TrkB) signaling. The siRNAs treatment decreased GR, but not MR, protein expression, and significantly enhanced expression levels of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) in the brain. Of interest, GR knockdown suppressed BDNF/TrkB signaling in adult mice brains. Importantly, GR siRNA pretreatment significantly increased the infarction size and exacerbated the neurobehavioral deficits induced by MCAO in comparison to the control group. Thus, the present study demonstrates the important role of GR in the regulation of the inflammatory responses and neurotrophic BDNF/TrkB signaling pathway in acute ischemic brain injuries in adult mice, revealing a new insight into the pathogenesis and therapeutic potential in acute ischemic strokes.
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Concepcion KR, Zhang L. Corticosteroids and perinatal hypoxic-ischemic brain injury. Drug Discov Today 2018; 23:1718-1732. [PMID: 29778695 DOI: 10.1016/j.drudis.2018.05.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/13/2018] [Accepted: 05/11/2018] [Indexed: 01/15/2023]
Abstract
Perinatal hypoxic-ischemic (HI) brain injury is the major cause of neonatal mortality and severe long-term neurological morbidity. Yet, the effective therapeutic interventions currently available are extremely limited. Corticosteroids act on both mineralocorticoid (MR) and glucocorticoid (GR) receptors and modulate inflammation and apoptosis in the brain. Neuroinflammatory response to acute cerebral HI is a major contributor to the pathophysiology of perinatal brain injury. Here, we give an overview of current knowledge of corticosteroid-mediated modulations of inflammation and apoptosis in the neonatal brain, focusing on key regulatory cells of the innate and adaptive immune response. In addition, we provide new insights into targets of MR and GR in potential therapeutic strategies that could be beneficial for the treatment of infants with HI brain injury.
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Affiliation(s)
- Katherine R Concepcion
- Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
| | - Lubo Zhang
- Lawrence D. Longo, MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
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Menshanov PN, Bannova AV, Dygalo NN. Anoxia ameliorates the dexamethasone-induced neurobehavioral alterations in the neonatal male rat pups. Horm Behav 2017; 87:122-128. [PMID: 27865789 DOI: 10.1016/j.yhbeh.2016.11.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 11/11/2016] [Accepted: 11/14/2016] [Indexed: 01/03/2023]
Abstract
Glucocorticoids and hypoxia are two essential factors affecting the brain development during labor and delivery. In addition to the neurobehavioral alterations induced separately by these factors, glucocorticoids can attenuate the deleterious consequences of severe hypoxia-ischemia on the brain development, acting as a neuroprotective agent in combination with hypoxia. The role of hypoxia in the combined action with corticosteroids is less clear. Severe hypoxia-ischemia results in the massive activation of caspase-3, masking any other effects of hypoxia on the neonatal brain exposed to glucocorticoids. As a result, the effects of mild hypoxia on the developing brain pretreated with glucocorticoids remain unclear. To analyze this problem, 2-day-old male rats were treated with dexamethasone (DEX) before the subsequent exposure to mild 10-min anoxia or normoxia. The treatment with only DEX resulted in the delay in the development of the negative geotaxis reaction and in the decrease in locomotor activity of the neonatal male pups. The mild anoxic event attenuated these DEX-induced neurobehavioral alterations. The treatment with DEX, but not the mild anoxic exposure alone, resulted in the delayed upregulation of active caspase-3 in the prefrontal cortex and in the brainstem of the male pups. This glucocorticoid-induced upregulation of active caspase-3 was prevented by the anoxic event. The present findings evidence that mild anoxia is capable of ameliorating the glucocorticoid-induced neurodevelopmental alterations in the neonatal rats if the artificial or the naturally occurring increase in the levels of glucocorticoids occurred just before the episode of hypoxia.
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Affiliation(s)
- Petr N Menshanov
- Functional Neurogenomics Laboratory, Institute of Cytology and Genetics, Russian Academy of Science, Novosibirsk, Russian Federation; Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russian Federation.
| | - Anita V Bannova
- Functional Neurogenomics Laboratory, Institute of Cytology and Genetics, Russian Academy of Science, Novosibirsk, Russian Federation
| | - Nikolay N Dygalo
- Functional Neurogenomics Laboratory, Institute of Cytology and Genetics, Russian Academy of Science, Novosibirsk, Russian Federation; Department of Natural Sciences, Novosibirsk State University, Novosibirsk, Russian Federation
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Ohshima M, Taguchi A, Tsuda H, Sato Y, Yamahara K, Harada-Shiba M, Miyazato M, Ikeda T, Iida H, Tsuji M. Intraperitoneal and intravenous deliveries are not comparable in terms of drug efficacy and cell distribution in neonatal mice with hypoxia-ischemia. Brain Dev 2015; 37:376-86. [PMID: 25034178 DOI: 10.1016/j.braindev.2014.06.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 06/23/2014] [Accepted: 06/23/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND PURPOSE Most therapeutic agents are administered intravenously (IV) in clinical settings and intraperitoneally (IP) in preclinical studies with neonatal rodents; however, it remains unclear whether intraperitoneal (IP) injection is truly an acceptable alternative for intravenous (IV) injection in preclinical studies. The objective of our study is to clarify the differences in the therapeutic effects of drugs and in the distribution of infused cells after an IP or IV injection in animals with brain injury. METHODS Dexamethasone or MK-801, an N-methyl-d-aspartate receptor antagonist was administered either IP or IV in a mouse model of neonatal hypoxic-ischemic encephalopathy. Green fluorescent protein-expressing mesenchymal stem cells (MSCs) or mononuclear cells (MNCs) were injected IP or IV in the mouse model. Two hours and 24h after the administration of the cells, we investigated the cell distributions by immunohistochemical staining. We also investigated distribution of IV administered MNCs labeled with 2-[18F]fluoro-2-deoxy-d-glucose in a juvenile primate, a macaque with stroke 1h after the administration. RESULTS IP and IV administration of dexamethasone attenuated the brain injury to a similar degree. IP administration of MK-801 attenuated brain injury, whereas IV administration of MK-801 did not. The IV group showed a significantly greater number of infused cells in the lungs and brains in the MSC cohort and in the spleen, liver, and lung in the MNC cohort compared to the IP group. In the macaque, MNCs were detected in the spleen and liver in large amounts, but not in the brain and lungs. CONCLUSIONS This study demonstrated that the administration route influences the effects of drugs and cell distribution. Therefore, a preclinical study may need to be performed using the optimal administration route used in a clinical setting.
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Affiliation(s)
- Makiko Ohshima
- Department of Regenerative Medicine and Tissue Engineering, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
| | - Akihiko Taguchi
- Department of Regenerative Medicine Research, Institute of Biomedical Research Innovation, Kobe, Hyogo, Japan
| | - Hidetoshi Tsuda
- Department of Regenerative Medicine and Tissue Engineering, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
| | - Yoshiaki Sato
- Division of Neonatology, Center for Maternal-Neonatal Care, Nagoya University Hospital, Nagoya, Aichi, Japan
| | - Kenichi Yamahara
- Department of Regenerative Medicine and Tissue Engineering, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
| | - Mariko Harada-Shiba
- Department of Regenerative Medicine and Tissue Engineering, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
| | - Mikiya Miyazato
- Department of Biochemistry, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
| | - Tomoaki Ikeda
- Department of Obstetrics and Gynecology, Mie University School of Medicine, Tsu, Mie, Japan
| | - Hidehiro Iida
- Department of Investigative Radiology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
| | - Masahiro Tsuji
- Department of Regenerative Medicine and Tissue Engineering, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
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Gonzalez-Rodriguez PJ, Li Y, Martinez F, Zhang L. Dexamethasone protects neonatal hypoxic-ischemic brain injury via L-PGDS-dependent PGD2-DP1-pERK signaling pathway. PLoS One 2014; 9:e114470. [PMID: 25474649 PMCID: PMC4256424 DOI: 10.1371/journal.pone.0114470] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 11/11/2014] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND AND PURPOSE Glucocorticoids pretreatment confers protection against neonatal hypoxic-ischemic (HI) brain injury. However, the molecular mechanism remains poorly elucidated. We tested the hypothesis that glucocorticoids protect against HI brain injury in neonatal rat by stimulation of lipocalin-type prostaglandin D synthase (L-PGDS)-induced prostaglandin D2 (PGD2)-DP1-pERK mediated signaling pathway. METHODS Dexamethasone and inhibitors were administered via intracerebroventricular (i.c.v) injections into 10-day-old rat brains. Levels of L-PGD2, D prostanoid (DP1) receptor, pERK1/2 and PGD2 were determined by Western immunoblotting and ELISA, respectively. Brain injury was evaluated 48 hours after conduction of HI in 10-day-old rat pups. RESULTS Dexamethasone pretreatment significantly upregulated L-PGDS expression and the biosynthesis of PGD2. Dexamethasone also selectively increased isoform pERK-44 level in the neonatal rat brains. Inhibitors of L-PGDS (SeCl4), DP1 (MK-0524) and MAPK (PD98059) abrogated dexamethasone-induced increases in pERK-44 level, respectively. Of importance, these inhibitors also blocked dexamethasone-mediated neuroprotective effects against HI brain injury in neonatal rat brains. CONCLUSION Interaction of glucocorticoids-GR signaling and L-PGDS-PGD2-DP1-pERK mediated pathway underlies the neuroprotective effects of dexamethasone pretreatment in neonatal HI brain injury.
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Affiliation(s)
- Pablo J. Gonzalez-Rodriguez
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, 92350, United States of America
| | - Yong Li
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, 92350, United States of America
| | - Fabian Martinez
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, 92350, United States of America
| | - Lubo Zhang
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, California, 92350, United States of America
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Gonzalez-Rodriguez PJ, Xiong F, Li Y, Zhou J, Zhang L. Fetal hypoxia increases vulnerability of hypoxic-ischemic brain injury in neonatal rats: role of glucocorticoid receptors. Neurobiol Dis 2014; 65:172-9. [PMID: 24513088 DOI: 10.1016/j.nbd.2014.01.020] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 01/20/2014] [Accepted: 01/30/2014] [Indexed: 12/21/2022] Open
Abstract
Gestational hypoxia is a common stress to the fetal development and increases the risk of neonatal morbidity. The present study tested the hypothesis that fetal hypoxia results in heightened brain vulnerability to hypoxic-ischemic (HI) injury in neonatal rats via down-regulation of glucocorticoid receptor (GR) in the developing brain. Time-dated pregnant rats were exposed to hypoxia (10.5% O2) from days 15 to 21 of gestation. Brain HI injury was determined in day 10 pups. Maternal hypoxia resulted in asymmetric intrauterine growth restriction in the fetus. The brain HI injury was significantly increased in maternal hypoxia-treated pups as compared with the normoxia control in both males and females. Activation of brain GR by dexamethasone injection into the right lateral ventricle produced a concentration-dependent reduction of HI-induced brain injury in control pups. Maternal hypoxia significantly decreased GR mRNA and protein abundance in the fetal brain and neonatal hippocampus and abolished the dexamethasone-mediated neuroprotective effect in pup brains. This decreased GR expression was resulted from increased DNA methylation, decreased binding of transcription factors Egr-1 and Sp1 to GR gene exon 17 and 111 promoters, and reduced expression of GR exon 17 and 111 mRNA variants. The results demonstrate that gestational hypoxia causes epigenetic repression of GR gene expression in the developing brain resulting in the heightened brain vulnerability to HI injury in neonatal rats.
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Affiliation(s)
- Pablo J Gonzalez-Rodriguez
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Fuxia Xiong
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Yong Li
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Jianjun Zhou
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
| | - Lubo Zhang
- Center for Perinatal Biology, Division of Pharmacology, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
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Charles MS, Ostrowski RP, Manaenko A, Duris K, Zhang JH, Tang J. Role of the pituitary–adrenal axis in granulocyte-colony stimulating factor-induced neuroprotection against hypoxia–ischemia in neonatal rats. Neurobiol Dis 2012; 47:29-37. [PMID: 22779090 DOI: 10.1016/j.nbd.2012.03.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Several reports indicate that the activity of the hypothalamic–pituitary–adrenal axis (HPA) is increased after a brain insult and that its down-regulation can improve detrimental outcomes associated with ischemic brain injuries.Granulocyte-colony stimulating factor (G-CSF) is a neuroprotective drug shown in the naïve rat to regulate hormones of the HPA axis. In this study we investigate whether G-CSF confers its neuroprotective properties by influencing the HPA response after neonatal hypoxia–ischemia (HI). Following the Rice–Vannucci model, seven day old rats (P7)were subjected to unilateral carotid ligation followed by 2.5 h of hypoxia. To test our hypothesis,metyrapone was administered to inhibit the release of rodent specific glucocorticoid, corticosterone, at the adrenal level. Dexamethasone, a synthetic glucocorticoid, was administered to agonize the effects of corticosterone.Our results show that both G-CSF and metyrapone significantly reduced infarct volume while dexamethasone treatment did not reduce infarct size even when combined with G-CSF. The protective effects of G-CSF do not include blood brain barrier preservation as suggested by the brain edema results. G-CSF did not affect the pituitary released adrenocorticotropic hormone (ACTH) levels in the blood plasma at 4 h, but suppressed the increase of corticosterone in the blood. The administration of G-CSF and metyrapone increased weight gain, and significantly reduced the Bax/Bcl-2 ratio in the brain while dexamethasone reversed the effects of G-CSF. The combination of G-CSF and metyrapone significantly decreased caspase-3 protein levels in the brain, and the effect was antagonized by dexamethasone.We report that G-CSF is neuroprotective in neonatal HI by reducing infarct volume, by suppressing the HI-induced increase of the Bax/Bcl-2 ratio, and by decreasing corticosterone in the blood. Metyrapone was able to confer similar neuroprotection as G-CSF while dexamethasone reversed the effects of G-CSF. In conclusion, we show that decreasing HPA axis activity is neuroprotective after neonatal HI, which can be conferred by administering G-CSF.
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Affiliation(s)
- Mélissa S Charles
- Department of Microbiology and Molecular Genetics, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
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Fetal stress and programming of hypoxic/ischemic-sensitive phenotype in the neonatal brain: mechanisms and possible interventions. Prog Neurobiol 2012; 98:145-65. [PMID: 22627492 DOI: 10.1016/j.pneurobio.2012.05.010] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 05/10/2012] [Accepted: 05/11/2012] [Indexed: 12/12/2022]
Abstract
Growing evidence of epidemiological, clinical and experimental studies has clearly shown a close link between adverse in utero environment and the increased risk of neurological, psychological and psychiatric disorders in later life. Fetal stresses, such as hypoxia, malnutrition, and fetal exposure to nicotine, alcohol, cocaine and glucocorticoids may directly or indirectly act at cellular and molecular levels to alter the brain development and result in programming of heightened brain vulnerability to hypoxic-ischemic encephalopathy and the development of neurological diseases in the postnatal life. The underlying mechanisms are not well understood. However, glucocorticoids may play a crucial role in epigenetic programming of neurological disorders of fetal origins. This review summarizes the recent studies about the effects of fetal stress on the abnormal brain development, focusing on the cellular, molecular and epigenetic mechanisms and highlighting the central effects of glucocorticoids on programming of hypoxic-ischemic-sensitive phenotype in the neonatal brain, which may enhance the understanding of brain pathophysiology resulting from fetal stress and help explore potential targets of timely diagnosis, prevention and intervention in neonatal hypoxic-ischemic encephalopathy and other brain disorders.
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Ohshima M, Tsuji M, Taguchi A, Kasahara Y, Ikeda T. Cerebral blood flow during reperfusion predicts later brain damage in a mouse and a rat model of neonatal hypoxic-ischemic encephalopathy. Exp Neurol 2011; 233:481-9. [PMID: 22143064 DOI: 10.1016/j.expneurol.2011.11.025] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 11/11/2011] [Indexed: 12/01/2022]
Abstract
Children with severe neonatal hypoxic-ischemic encephalopathy (HIE) die or develop life-long neurological impairments such as cerebral palsy and mental retardation. Decreased regional cerebral blood flow (CBF) is believed to be the predominant factor that determines the level of tissue injury in the immature brain. However, the spatio-temporal profiles of CBF after neonatal HIE are not well understood. CB17 mouse and Wistar rat pups were exposed to a unilateral hypoxic-ischemic (HI) insult at eight or seven days of age. Laser speckle imaging sequentially measured the cortical surface CBF before the hypoxic exposure and until 24h after the hypoxic exposure. Seven days after the HI insult, brain damage was morphologically assessed by measuring the hemispheric volumes and by semi-quantitative scoring for neuropathologic injury. The mean CBF on the ipsilateral hemisphere in mice decreased after carotid artery ligation. After the end of hypoxic insult (i.e., the reperfusion phase), the mean CBF level gradually rose and nearly attained its pre-surgery level by 9h of reperfusion. It then decreased. The degree of reduced CBF during reperfusion was well correlated with the degree of later morphological brain damage. The correlation was the strongest when the CBF was measured in the ischemic core region at 24h of reperfusion in mice (R²=0.89). A similar trend in results was found in rats. These results suggest that the CBF level during reperfusion may be a useful predictive factor for later brain damage in immature mice. This may enable optimizing brain damage for detail analyses.
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Affiliation(s)
- Makiko Ohshima
- Department of Regenerative Medicine and Tissue Engineering, National Cerebral and Cardiovascular Center Research Institute, 5-7-1, Fujishiro-dai, Suita, Osaka, 565-8565, Japan.
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Trousson A, Grenier J, Fonte C, Massaad-Massade L, Schumacher M, Massaad C. Recruitment of the p160 coactivators by the glucocorticoid receptor: dependence on the promoter context and cell type but not hypoxic conditions. J Steroid Biochem Mol Biol 2007; 104:305-11. [PMID: 17481888 DOI: 10.1016/j.jsbmb.2007.03.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the nervous system, glucocorticoids exert beneficial or noxious effects, depending on their concentration and time-exposure. They act via the glucocorticoid receptor (GR) which recruits the p160 coactivators (SRC-1, SRC-2 and SRC-3). It was often shown that the three SRCs are interchangeable. The aim of the present study was to evaluate if the GR-SRCs interactions are dependent on several parameters like the target promoter structure, cell type or exogenous stressful parameters like hypoxia. We investigated the GR-SRCs interactions in two glial cells: astrocytes for the central nervous system and Schwann cells for the peripheral nervous system. We have shown by performing functional studies (overexpression and siRNA knock-down) that the recruitment of the three p160 by the GR is promoter-dependent and cell-specific. Moreover, we have shown that hypoxia (5% of oxygen) enhanced GR transactivation in both glial cells. Although hypoxia enhanced GR transactivation, it did not alter the interactions between the GR and the three p160s. Finally, we have shown that the potentiation of GR transactivation by hypoxia is due to an increase of the GR transcripts in Schwann cells but not in astrocytes. Altogether, these results reveal that the p160s are not interchangeable and that their recruitment by the GR is a multiparametric event.
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Affiliation(s)
- Amalia Trousson
- Inserm UMR788, Université Paris-Sud 11, 80, rue du Général Leclerc 94276 Le Kremlin-Bicêtre Cedex, France
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Ikeda T, Mishima K, Yoshikawa T, Iwasaki K, Fujiwara M, Xia YX, Ikenoue T. Dexamethasone prevents long-lasting learning impairment following neonatal hypoxic-ischemic brain insult in rats. Behav Brain Res 2002; 136:161-70. [PMID: 12385801 DOI: 10.1016/s0166-4328(02)00107-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We examined for 18 weeks the effect of dexamethasone treatment on learning and memory impairment produced by hypoxic-ischemic stress at postnatal day 7 in rat in addition to brain histological study. Dexamethasone of 0.5 mg/kg was injected i.p. 4 h before hypoxic-ischemic stress, in which the left carotid artery was ligated followed by 2 h hypoxia (8% oxygen). Dexamethasone treatment improved behavior in each learning task: in choice reaction time tasks relating to the attention process, in 8-arm radial maze task examining working and reference memory, and in water maze task relating to reference memory. Improvement to the extent of the sham-control level was observed. Dexamethasone treatment also completely prevented histological brain damage. No adverse effect in learning and memory tests was observed in the animals treated with dexamethasone without hypoxic-ischemic stress. It is concluded that dexamethasone treatment is significantly effective in prevention not only of histological brain damage but also of learning and memory impairment occasioned by subsequent hypoxic-ischemic insult, warranting further clinical investigation.
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Affiliation(s)
- Tomoaki Ikeda
- Department of Obstetrics and Gynecology, Miyazaki Medical College, 5200 Kihara, Kiyotake-Cho, Japan.
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Dardzinski BJ, Smith SL, Towfighi J, Williams GD, Vannucci RC, Smith MB. Increased plasma beta-hydroxybutyrate, preserved cerebral energy metabolism, and amelioration of brain damage during neonatal hypoxia ischemia with dexamethasone pretreatment. Pediatr Res 2000; 48:248-55. [PMID: 10926303 DOI: 10.1203/00006450-200008000-00021] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Dexamethasone (DEX) pretreatment has been shown to be neuroprotective in a neonatal rat model of hypoxia ischemia (HI). The exact mechanism of this neuroprotection is still unknown. This study used 31P nuclear magnetic resonance spectroscopy to monitor energy metabolism during a 3-h episode of HI in 7-d-old rat pups in one of two groups. The first group was pretreated with 0.1 mL saline (i.p.) and the second group was treated with 0.1 mL of 0.1mg/kg DEX (i.p.) 22 h before HI. Animals pretreated with DEX had elevated nucleoside triphosphate and phosphocreatine levels during HI when compared with controls. Saline-treated animals had significant decreases in nucleoside triphosphate and phosphocreatine and increases in inorganic phosphate over this same period. 31P nuclear magnetic resonance data unequivocally demonstrate preservation of energy metabolism during HI in neonatal rats pretreated with DEX. Animals pretreated with DEX had little or no brain damage following 3 h of HI when compared with matched controls, which experienced severe neuronal loss and cortical infarction. These same pretreated animals had an increase in blood beta-hydroxybutyrate levels before ischemia, suggesting an increase in ketone bodies, which is the neonate's primary energy source. Elevation of ketone bodies appears to be one of the mechanisms by which DEX pretreatment provides neuroprotection during HI in the neonatal rat.
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Affiliation(s)
- B J Dardzinski
- Department of Radiology and Pediatrics, University of Cincinnati College of Medicine, Imaging Research Center, Children's Hospital Medical Center, Ohio 45229, USA
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Nakayama M, Uchimura K, Zhu RL, Nagayama T, Rose ME, Stetler RA, Isakson PC, Chen J, Graham SH. Cyclooxygenase-2 inhibition prevents delayed death of CA1 hippocampal neurons following global ischemia. Proc Natl Acad Sci U S A 1998; 95:10954-9. [PMID: 9724811 PMCID: PMC28002 DOI: 10.1073/pnas.95.18.10954] [Citation(s) in RCA: 268] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/1998] [Accepted: 07/17/1998] [Indexed: 11/18/2022] Open
Abstract
The inducible isoform of the enzyme cyclooxygenase-2 (COX2) is an immediate early gene induced by synaptic activity in the brain. COX2 activity is an important mediator of inflammation, but it is not known whether COX2 activity is pathogenic in brain. To study the role of COX2 activity in ischemic injury in brain, expression of COX2 mRNA and protein and the effect of treatment with a COX2 inhibitor on neuronal survival in a rat model of global ischemia were determined. Expression of both COX2 mRNA and protein was increased after ischemia in CA1 hippocampal neurons before their death. There was increased survival of CA1 neurons in rats treated with the COX2-selective inhibitor SC58125 [1-[(4-methylsulfonyl) phenyl]-3-trifluoro-methyl-5-[(4-fluoro)phenyl] pyrazole] before or after global ischemia compared with vehicle controls. Furthermore, hippocampal prostaglandin E2 concentrations 24 h after global ischemia were decreased in drug-treated animals compared with vehicle-treated controls. These results suggest that COX2 activity contributes to CA1 neuronal death after global ischemia.
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Affiliation(s)
- M Nakayama
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15213, USA
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