异丙酚对氨处理的大鼠脑星形胶质细胞水通道蛋白-4表达以及细胞水肿的影响
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摘要
目的:研究异丙酚对氯化铵处理的大鼠脑皮质星形胶质细胞水通道蛋白-4(AQP-4)表达和细胞水肿的影响以及相关的作用机制。
方法:体外培养Sprague Dawley大鼠脑皮质星形胶质细胞。待细胞培养3-4周左右时,用细胞免疫荧光标记星形胶质细胞特异性蛋白神经胶质酸性蛋白,星形胶质细胞纯度达95%以上的细胞备用。实验分组第一步:正常对照组、氯化铵(5mM)处理星形胶质细胞6h、12h、24h、48h组。取AQP-4表达明显升高的一个时间点24h作为药物处理后检测AQP-4的时间点。第二步:正常对照组、氯化铵(5mM)处理星形胶质细胞0.5h、6h、12h、24h组。取p-p38表达明显升高的时间点0.5h作为药物处理后检测p-p38的时间点。第三步:正常对照组、氯化铵(5mM)组、溶剂(DMSO)对照组、p38特异性抑制剂SB203580(10μM)组、异丙酚(10μM)组。其中溶剂、p38特异性抑制剂和异丙酚均分别与氯化铵共培养星形胶质细胞。用细胞免疫荧光法检测培养的星形胶质细胞纯度;用光学显微镜观察各组细胞形态,用蛋白免疫印迹法(western-blot)检测AQP-4、p38和p-p38的表达情况。
结果:1、培养的星形胶质细胞的纯度为96.6%±1.4%。2、氯化铵处理星形胶质细胞12h后,AQP-4蛋白表达较正常对照组明显增加(P＜0.01),一直持续到48h。
3、氯化铵处理星形胶质细胞后p38蛋白表达无明显变化;p-p38蛋白表达在氯化铵处理0.5h后较正常对照组明显增高(P＜0.05),在作用24h后p-p38表达仍明显升高。4、光学显微镜观察发现氯化铵处理的星形胶质细胞较正常组细胞肿胀明显,异丙酚和p38抑制剂能减轻氯化铵引起的细胞肿胀程度。异丙酚和p38抑制剂处理组星形胶质细胞AQP-4和p-p38蛋白表达较氯化铵处理组降低(P＜0.05)。p38蛋白表达在各组之间无明显统计学差异(P=0.341)。
结论:异丙酚能抑制氯化铵弓j起的星形胶质细胞AQP-4的表达上调,减轻细胞的肿胀程度,其作用可能与抑制p38信号途径激活有关。
Background: Astrocyte swelling is an important consequence of hepatic encephalopathy, and aquaporin-4 (AQP-4) has been reported to play vital role in this swelling. Ammonia causes astrocyte swelling and is also known to modulate AQP-4 expression in the astrocyte foot. Propofol is used to control intracranial pressure by reduce cerebral edema. The purpose of this article was to investigate the effects of propofol on ammonia-induced astrocyte swelling and AQP-4 expression in rats and its possible mechanisms.
Methods: Astrocytes were separated from newborn Sprague Dawley rats. After cultured for 3-4 weeks, fluorescent glial fibrillary acidic protein labeling was used to evaluate the purity of cultured astrocytes, which achieved to 95% was considered to be used in this study. Cultured astrocytes were randomly divided into several groups, step 1: normal control group, ammonia-incubated for 6h, 12h, 24h, 48h group. We selected the 24h as the point we detected the expression of aquaporin-4 after we treated with drugs below; step 2: normal control group, ammonia-incubated for 0.5h, 6h, 12h, 24h group. We selected the 0.5h as the point we detect the expression of p-p38 after we treated with drugs below; step 3: normal control group, ammonia-incubated for 24h group, dimethyl sulfoxide (DMSO) control group, p38 antagonist SB203580(10μM) treatment group, propofol(10μM) treatment group. The purity of cultured astrocytes was evaluated by fluorescent glial fibrillary acidic protein labeling; cell morphology was assessed by light microscopy; the expression of AQP-4, p38 and p-p38 were detected by westem-blot analysis.
Results: The purity of cultured astrocytes was achieved to 96.6%±1.4%. Astrocytes swelled significantly when exposed to 5 mM NH_4Cl for 24 h as compared to non-exposed astrocytes. Co-treatment with SB203580 (an inhibitor of p38) or propofol attenuated the degree of NH_4Cl-induced astrocyte swelling. Western blot analysis revealed that the expression levels of phospho-p38 and AQP-4 in NH_4Cl-treated cells were significantly increased relative to the control group (P < 0.05); SB203580 or propofol co-treatment inhibited the increased expression of p-p38 and AQP-4 relative to the NH_4Cl-treated group (P < 0.05). There were no significant differences in total p38 expression among the groups (P =0.341).
Conclusions: Ammonia-induced over-expression of AQP4 in astrocytes is regulated by the p38 MAPK pathway. Propofol prevented ammonia-induced AQP-4 protein over-expression may through inhibiting p38 MAPK activation.
方法:体外培养Sprague Dawley大鼠脑皮质星形胶质细胞。待细胞培养3-4周左右时,用细胞免疫荧光标记星形胶质细胞特异性蛋白神经胶质酸性蛋白,星形胶质细胞纯度达95%以上的细胞备用。实验分组第一步:正常对照组、氯化铵(5mM)处理星形胶质细胞6h、12h、24h、48h组。取AQP-4表达明显升高的一个时间点24h作为药物处理后检测AQP-4的时间点。第二步:正常对照组、氯化铵(5mM)处理星形胶质细胞0.5h、6h、12h、24h组。取p-p38表达明显升高的时间点0.5h作为药物处理后检测p-p38的时间点。第三步:正常对照组、氯化铵(5mM)组、溶剂(DMSO)对照组、p38特异性抑制剂SB203580(10μM)组、异丙酚(10μM)组。其中溶剂、p38特异性抑制剂和异丙酚均分别与氯化铵共培养星形胶质细胞。用细胞免疫荧光法检测培养的星形胶质细胞纯度;用光学显微镜观察各组细胞形态,用蛋白免疫印迹法(western-blot)检测AQP-4、p38和p-p38的表达情况。
结果:1、培养的星形胶质细胞的纯度为96.6%±1.4%。2、氯化铵处理星形胶质细胞12h后,AQP-4蛋白表达较正常对照组明显增加(P＜0.01),一直持续到48h。
3、氯化铵处理星形胶质细胞后p38蛋白表达无明显变化;p-p38蛋白表达在氯化铵处理0.5h后较正常对照组明显增高(P＜0.05),在作用24h后p-p38表达仍明显升高。4、光学显微镜观察发现氯化铵处理的星形胶质细胞较正常组细胞肿胀明显,异丙酚和p38抑制剂能减轻氯化铵引起的细胞肿胀程度。异丙酚和p38抑制剂处理组星形胶质细胞AQP-4和p-p38蛋白表达较氯化铵处理组降低(P＜0.05)。p38蛋白表达在各组之间无明显统计学差异(P=0.341)。
结论:异丙酚能抑制氯化铵弓j起的星形胶质细胞AQP-4的表达上调,减轻细胞的肿胀程度,其作用可能与抑制p38信号途径激活有关。
Background: Astrocyte swelling is an important consequence of hepatic encephalopathy, and aquaporin-4 (AQP-4) has been reported to play vital role in this swelling. Ammonia causes astrocyte swelling and is also known to modulate AQP-4 expression in the astrocyte foot. Propofol is used to control intracranial pressure by reduce cerebral edema. The purpose of this article was to investigate the effects of propofol on ammonia-induced astrocyte swelling and AQP-4 expression in rats and its possible mechanisms.
Methods: Astrocytes were separated from newborn Sprague Dawley rats. After cultured for 3-4 weeks, fluorescent glial fibrillary acidic protein labeling was used to evaluate the purity of cultured astrocytes, which achieved to 95% was considered to be used in this study. Cultured astrocytes were randomly divided into several groups, step 1: normal control group, ammonia-incubated for 6h, 12h, 24h, 48h group. We selected the 24h as the point we detected the expression of aquaporin-4 after we treated with drugs below; step 2: normal control group, ammonia-incubated for 0.5h, 6h, 12h, 24h group. We selected the 0.5h as the point we detect the expression of p-p38 after we treated with drugs below; step 3: normal control group, ammonia-incubated for 24h group, dimethyl sulfoxide (DMSO) control group, p38 antagonist SB203580(10μM) treatment group, propofol(10μM) treatment group. The purity of cultured astrocytes was evaluated by fluorescent glial fibrillary acidic protein labeling; cell morphology was assessed by light microscopy; the expression of AQP-4, p38 and p-p38 were detected by westem-blot analysis.
Results: The purity of cultured astrocytes was achieved to 96.6%±1.4%. Astrocytes swelled significantly when exposed to 5 mM NH_4Cl for 24 h as compared to non-exposed astrocytes. Co-treatment with SB203580 (an inhibitor of p38) or propofol attenuated the degree of NH_4Cl-induced astrocyte swelling. Western blot analysis revealed that the expression levels of phospho-p38 and AQP-4 in NH_4Cl-treated cells were significantly increased relative to the control group (P < 0.05); SB203580 or propofol co-treatment inhibited the increased expression of p-p38 and AQP-4 relative to the NH_4Cl-treated group (P < 0.05). There were no significant differences in total p38 expression among the groups (P =0.341).
Conclusions: Ammonia-induced over-expression of AQP4 in astrocytes is regulated by the p38 MAPK pathway. Propofol prevented ammonia-induced AQP-4 protein over-expression may through inhibiting p38 MAPK activation.
引文
[1] Blei AT. The pathophysiology of brain edema in acute liver failure. Neurochem Int 2005; 47:71-77.
[2] Kato M, Hughes RD, Keays RT, Williams R. Electron microscopic study of brain capillaries in cerebral edema from fulminant hepatic failure. Hepatology 1992 Jun; 15:1060-1066.
[3] Willard-Mack CL, Koehler RC, Hirata T, Cork LC, Takahashi H, Traystman RJ, Brusilow SW. Inhibition of glutamine synthetase reduces ammonia-induced astrocyte swelling in rat. Neuroscience. 1996; 71:589-599.
[4] Ganz R, Swain M, Traber P, DalCanto M, Butterworth RF, Blei AT. Ammonia-induced swelling of rat cerebral cortical slices: implications for the pathogenesis of brain edema in acute hepatic failure. Metab Brain Dis 1989; 4:213-223.
[5] Yang B, Zador Z, Verkman AS. Glial cell aquaporin-4 overexpression in transgenic mice accelerates cytotoxic brain swelling. J Biol Chem, 2008 May 30; 283(22): 15280-15286.
[6] Rama Rao KV, Chen M, Simard JM, et al. Increased aquaporin-4 expression in ammonia-treated cultured astrocytes. Neuroreport, 2003; 14:2379-2382.
[7] Jayakumar AR, Panickar KS, Murthy ChR, Norenberg MD. Oxidative stress and mitogen-activated protein kinase phosphorylation mediate ammonia-induced cell swelling and glutamate uptake inhibition in cultured astrocytes. J Neurosci 2006 3; 26:4774-4784.
[8] Lian-Hua Chen, Qin-Yan Gong, YU Zhang, et al. Effects of propofol,midazolam and thiopental sodium on outcome of focal cerebral ischemia-reperfusion in rats. Chin J Drugs Clin Rem. 2001; 20:81-87.
[9] Ishii H, Arail T, Segawa H, et al. Effects of propofol on lactate accumulation and oedema formation in focal cerebral ischemia in hyperglycaemic rats. Br J Anaesth, 2002 Mar; 88(3):412-417.
[10] Zheng YY, Lan YP, Zhu SM, et al. Propofol pretreatment attenuates aquaporin-4 over-expression and alleviates cerebral edema after transient focal brain ischemia reperfusion in rats. Anesth Analg. 2008 Dec; 107(6):2009-2016.
[11] Amiry-Moghaddam M, Xue R, Haug FMS, et al. Alpha-syntrophin deletion removes the perivascular but not endothelial pool of aquaporin-4 at the blood-brain barrier and delays the development of brain edema in an experimental model of acute hyponatremia. FASEB J, 2004; 18:542-544.
[12] Manley GT, Fujimura M, Ma T, et al. Aquaporin-4 deletion in mice reduces brain edema after acute water intoxication and ischemic stroke. Nat Med, 2000; 6:159-163.
[13] Papadopoulos MC, Verkman AS. Aquaporin-4 gene disruption in mice reduces brain swelling and mortality in pneumococcal meningitis. J Biol Chem, 2005; 280:13906-13912.
[14] Arima H, Yamamoto N, Sobue K, et al. Hyperosmolar mannitol simulates expression of aquaporins 4 and 9 through a p38 mitogen-activated protein kinase-dependent pathway in rat astrocytes. J Biol Chem, 2003; 278:44525-44534.
[15] Morishima T, Aoyama M,Tida Y, et al. Lactic acid increased aquaporin-4 expression on the cell membrance of cultured rat astrocytes. Neurosci Res, 2008; 61:18-26.
[16] Shawcross DL, Wright GA, Stadlbauer V, et al. Ammonia impairs neutrophil phagocyticfunction in liver disease. Hepatology. 2008 Oct; 48(4): 1202-1212.
[17] Cagnon L, Braissant O. CNTF protects oligodendrocytes from ammonia toxicity:intracellular signaling pathways involved. Neurobiol Dis. 2009 Jan; 33(1):133-142.
[18] Sinke AP, Jayakumar AR, Panickar KS, et al. NFkappaB in the mechanism of ammonia-induced astrocyte swelling in culture. J Neruochem, 2008 Sep; 106(6):2302-2311.
[19] Chen CJ, Liao SL, Kuo JS. Gliotoxic action of glutamate on cultured astrocytes. J Neurochem 2000; 75:1557-1565.
[20] Zielinska M, Law RO, Albrecht J. Excitotoxic mechanism of cell swelling in rat cerebral cortical slices treated acutely with ammonia. Neurochem Int. 2003; 43:299-303
[21] Tournier C, Thomas G, Pierre J, et al. Mediation by arachidonic acid metabolites of the H2O2-induced stimulation of mitogen-activated protein kinases. Eur J Biochem. 1997 Mar 1; 244(2):587-595.
[22] Acquaviva R, Campisi A, Murabito P, et al. Propofol attenuates peroxynitrite-mediated DNA damage and apoptosis in cultured astrocytes: an alternative protective mechanism. Anesthesiology, 2004 Dec; 101(6): 1363-1371.
[23] Daskalopoulos R, Korcok J, Farhangkhgoee P, et al. Propofol protection of sodium-hydrogen exchange activity sustains glutamate uptake during oxidative stress. Anesth Analg. 2001 Nov; 93(5): 1199-1204.
[1]Cordoba J,Alonso J,Rovira A,et al.The development of low-grade cerebral edema in cirrhosis is supported by the evolution of H-magnetic resonance abnormalities after liver transplantation.J Hepatol,2001;35:598-604.
[2]Smith SJ.Do astrocytes process neural information? Prog Brain Res,1992,94:119-136.
[3]Larsen FS,Gottstein J,Blei AT.Cerebral hyperemia and nitricoxide synthase in rats with ammonia-induced brain edema.J.Hepatol,2001;34:548-554.
[4]Blei AT,Larsen FS.Pathophysiology of cerebral edema in fulminant hepatic failure.J.Hepatol,1999;31:771-776.
[5]Bernal W,Hall C,Karvellas CJ,et al.Arterial ammonia and clinical risk factors for encephalopathy and intracranial hypertension in acute liver failure.Hepatology,2007;46(6):1844-1852.
[6] Romero Gomez M, Bautista JD, Grande L, et al. New concepts in the physiopathology of hepatic encephalopathy and therapeutic prospects. Gastroenterol Hepatol, 2004; 1:40-48.
[7] Kosenko E, Kaminsky Y, Kaminsky A, et al. Superoxide production and antioxidant enzymes in ammonia intoxication in rats. Free Rad. Res, 1997; 27:637-644.
[8] Venediktova NI, Lopata OV, Pogosian AS, et al. Antioxidant enzymes of the rat liver, brain, heart and erythrocytes in ammonia intoxication. Biomed Khim, 2005;51(2):185-191.
[9] Norenberg MD, Jayakumar AR, Rama Rao KV. Oxidative stress in the pathogenesis of hepatic encephalopathy. Metab. Brain Dis, 2004; 19:313-329.
[10] Arima H, Yamamoto N, Sobue K. Hyperosmolar mannitol simulates expression of aquaporins 4 and 9 through a p38 mitogen-activated protein kinase-dependent pathway in rat astrocytes. J Biol Chem, 2003; 278:44525-44534.
[11] Rama Rao KV, Jayakumar AR, Norenberg MD.Role of oxidative stress in the ammonia-induced mitochondrial permeability transition in cultured astrocytes. Neurochem Int, 2005; 47(1-2):31-38.
[12] Tanigami H, Rebel A, Martin LJ,et al. Effect of glutamine synthetase inhibition on astrocyte swelling and altered astroglial protein expression during hyperammonemia in rats. Neuroscience, 2005; 131(2):437-449.
[13] Norenberg MD, Rama Rao KV, Jayakumar AR. Mechanisms of Ammonia-Induced Astrocyte Swelling. Metab Brain Dis, 2005; 20(4):303-318.
[14] Murthy ChRK, Rama Rao KV, Bai G, et al. Ammonia induced production of free radicals in primary cultures of rat astrocytes. J. Neurosci. Res, 2001; 66:282-288.
[15] Bai G, Rama Rao KV, Murthy ChRK, et al. Ammonia induces the mitochondrial permeability transition in primary cultures of rat astrocytes. J. Neurosci. Res, 2001; 66:981-991.
[16] Belanger M, Desjardings P, Chatauret N,et al. Mild hypothermia prevents brain edema and attenuates up-regulation of the astrocytic benzodiazepine receptor in experimental acute liver failure. J Hepatol, 2005; 42(5):694-699.
[17] Bender AS, Norenberg MD. Ammonia enhances inhibitory effects of benzodiazepines and neurosteroids on K+ influx in astrocytes. Soc. Neurosci. Abstr, 1994; 20:1502.
[18] Bender AS, Norenberg MD. Effect of benzodiazepines and neurosteroids on ammonia-induced swelling in cultured astrocytes. J. Neurosci. Res, 1998; 54:673-680.
[19] Panickar KS, Jayakumar AR, Rama Rao KV, et al. Downregulation of the 18-kDa translocator protein: effects on the ammonia-induced mitochondrial permeability transition and cell swelling in cultured astrocytes. Glia, 2007; 55(16): 1720-1727.
[2] Kato M, Hughes RD, Keays RT, Williams R. Electron microscopic study of brain capillaries in cerebral edema from fulminant hepatic failure. Hepatology 1992 Jun; 15:1060-1066.
[3] Willard-Mack CL, Koehler RC, Hirata T, Cork LC, Takahashi H, Traystman RJ, Brusilow SW. Inhibition of glutamine synthetase reduces ammonia-induced astrocyte swelling in rat. Neuroscience. 1996; 71:589-599.
[4] Ganz R, Swain M, Traber P, DalCanto M, Butterworth RF, Blei AT. Ammonia-induced swelling of rat cerebral cortical slices: implications for the pathogenesis of brain edema in acute hepatic failure. Metab Brain Dis 1989; 4:213-223.
[5] Yang B, Zador Z, Verkman AS. Glial cell aquaporin-4 overexpression in transgenic mice accelerates cytotoxic brain swelling. J Biol Chem, 2008 May 30; 283(22): 15280-15286.
[6] Rama Rao KV, Chen M, Simard JM, et al. Increased aquaporin-4 expression in ammonia-treated cultured astrocytes. Neuroreport, 2003; 14:2379-2382.
[7] Jayakumar AR, Panickar KS, Murthy ChR, Norenberg MD. Oxidative stress and mitogen-activated protein kinase phosphorylation mediate ammonia-induced cell swelling and glutamate uptake inhibition in cultured astrocytes. J Neurosci 2006 3; 26:4774-4784.
[8] Lian-Hua Chen, Qin-Yan Gong, YU Zhang, et al. Effects of propofol,midazolam and thiopental sodium on outcome of focal cerebral ischemia-reperfusion in rats. Chin J Drugs Clin Rem. 2001; 20:81-87.
[9] Ishii H, Arail T, Segawa H, et al. Effects of propofol on lactate accumulation and oedema formation in focal cerebral ischemia in hyperglycaemic rats. Br J Anaesth, 2002 Mar; 88(3):412-417.
[10] Zheng YY, Lan YP, Zhu SM, et al. Propofol pretreatment attenuates aquaporin-4 over-expression and alleviates cerebral edema after transient focal brain ischemia reperfusion in rats. Anesth Analg. 2008 Dec; 107(6):2009-2016.
[11] Amiry-Moghaddam M, Xue R, Haug FMS, et al. Alpha-syntrophin deletion removes the perivascular but not endothelial pool of aquaporin-4 at the blood-brain barrier and delays the development of brain edema in an experimental model of acute hyponatremia. FASEB J, 2004; 18:542-544.
[12] Manley GT, Fujimura M, Ma T, et al. Aquaporin-4 deletion in mice reduces brain edema after acute water intoxication and ischemic stroke. Nat Med, 2000; 6:159-163.
[13] Papadopoulos MC, Verkman AS. Aquaporin-4 gene disruption in mice reduces brain swelling and mortality in pneumococcal meningitis. J Biol Chem, 2005; 280:13906-13912.
[14] Arima H, Yamamoto N, Sobue K, et al. Hyperosmolar mannitol simulates expression of aquaporins 4 and 9 through a p38 mitogen-activated protein kinase-dependent pathway in rat astrocytes. J Biol Chem, 2003; 278:44525-44534.
[15] Morishima T, Aoyama M,Tida Y, et al. Lactic acid increased aquaporin-4 expression on the cell membrance of cultured rat astrocytes. Neurosci Res, 2008; 61:18-26.
[16] Shawcross DL, Wright GA, Stadlbauer V, et al. Ammonia impairs neutrophil phagocyticfunction in liver disease. Hepatology. 2008 Oct; 48(4): 1202-1212.
[17] Cagnon L, Braissant O. CNTF protects oligodendrocytes from ammonia toxicity:intracellular signaling pathways involved. Neurobiol Dis. 2009 Jan; 33(1):133-142.
[18] Sinke AP, Jayakumar AR, Panickar KS, et al. NFkappaB in the mechanism of ammonia-induced astrocyte swelling in culture. J Neruochem, 2008 Sep; 106(6):2302-2311.
[19] Chen CJ, Liao SL, Kuo JS. Gliotoxic action of glutamate on cultured astrocytes. J Neurochem 2000; 75:1557-1565.
[20] Zielinska M, Law RO, Albrecht J. Excitotoxic mechanism of cell swelling in rat cerebral cortical slices treated acutely with ammonia. Neurochem Int. 2003; 43:299-303
[21] Tournier C, Thomas G, Pierre J, et al. Mediation by arachidonic acid metabolites of the H2O2-induced stimulation of mitogen-activated protein kinases. Eur J Biochem. 1997 Mar 1; 244(2):587-595.
[22] Acquaviva R, Campisi A, Murabito P, et al. Propofol attenuates peroxynitrite-mediated DNA damage and apoptosis in cultured astrocytes: an alternative protective mechanism. Anesthesiology, 2004 Dec; 101(6): 1363-1371.
[23] Daskalopoulos R, Korcok J, Farhangkhgoee P, et al. Propofol protection of sodium-hydrogen exchange activity sustains glutamate uptake during oxidative stress. Anesth Analg. 2001 Nov; 93(5): 1199-1204.
[1]Cordoba J,Alonso J,Rovira A,et al.The development of low-grade cerebral edema in cirrhosis is supported by the evolution of H-magnetic resonance abnormalities after liver transplantation.J Hepatol,2001;35:598-604.
[2]Smith SJ.Do astrocytes process neural information? Prog Brain Res,1992,94:119-136.
[3]Larsen FS,Gottstein J,Blei AT.Cerebral hyperemia and nitricoxide synthase in rats with ammonia-induced brain edema.J.Hepatol,2001;34:548-554.
[4]Blei AT,Larsen FS.Pathophysiology of cerebral edema in fulminant hepatic failure.J.Hepatol,1999;31:771-776.
[5]Bernal W,Hall C,Karvellas CJ,et al.Arterial ammonia and clinical risk factors for encephalopathy and intracranial hypertension in acute liver failure.Hepatology,2007;46(6):1844-1852.
[6] Romero Gomez M, Bautista JD, Grande L, et al. New concepts in the physiopathology of hepatic encephalopathy and therapeutic prospects. Gastroenterol Hepatol, 2004; 1:40-48.
[7] Kosenko E, Kaminsky Y, Kaminsky A, et al. Superoxide production and antioxidant enzymes in ammonia intoxication in rats. Free Rad. Res, 1997; 27:637-644.
[8] Venediktova NI, Lopata OV, Pogosian AS, et al. Antioxidant enzymes of the rat liver, brain, heart and erythrocytes in ammonia intoxication. Biomed Khim, 2005;51(2):185-191.
[9] Norenberg MD, Jayakumar AR, Rama Rao KV. Oxidative stress in the pathogenesis of hepatic encephalopathy. Metab. Brain Dis, 2004; 19:313-329.
[10] Arima H, Yamamoto N, Sobue K. Hyperosmolar mannitol simulates expression of aquaporins 4 and 9 through a p38 mitogen-activated protein kinase-dependent pathway in rat astrocytes. J Biol Chem, 2003; 278:44525-44534.
[11] Rama Rao KV, Jayakumar AR, Norenberg MD.Role of oxidative stress in the ammonia-induced mitochondrial permeability transition in cultured astrocytes. Neurochem Int, 2005; 47(1-2):31-38.
[12] Tanigami H, Rebel A, Martin LJ,et al. Effect of glutamine synthetase inhibition on astrocyte swelling and altered astroglial protein expression during hyperammonemia in rats. Neuroscience, 2005; 131(2):437-449.
[13] Norenberg MD, Rama Rao KV, Jayakumar AR. Mechanisms of Ammonia-Induced Astrocyte Swelling. Metab Brain Dis, 2005; 20(4):303-318.
[14] Murthy ChRK, Rama Rao KV, Bai G, et al. Ammonia induced production of free radicals in primary cultures of rat astrocytes. J. Neurosci. Res, 2001; 66:282-288.
[15] Bai G, Rama Rao KV, Murthy ChRK, et al. Ammonia induces the mitochondrial permeability transition in primary cultures of rat astrocytes. J. Neurosci. Res, 2001; 66:981-991.
[16] Belanger M, Desjardings P, Chatauret N,et al. Mild hypothermia prevents brain edema and attenuates up-regulation of the astrocytic benzodiazepine receptor in experimental acute liver failure. J Hepatol, 2005; 42(5):694-699.
[17] Bender AS, Norenberg MD. Ammonia enhances inhibitory effects of benzodiazepines and neurosteroids on K+ influx in astrocytes. Soc. Neurosci. Abstr, 1994; 20:1502.
[18] Bender AS, Norenberg MD. Effect of benzodiazepines and neurosteroids on ammonia-induced swelling in cultured astrocytes. J. Neurosci. Res, 1998; 54:673-680.
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