title: Aquaporin-4 inhibition mediates piroxicam-induced neuroprotection against focal cerebral ischemia/reperfusion injury in rodents.
abstract: OBJECTIVE
  Aquaporin-4(AQP4) is an abundant water channel protein in brain that regulates water transport to maintain homeostasis. Cerebral edema resulting from AQP4 over expression is considered to be one of the major determinants for progressive neuronal insult during cerebral ischemia. Although, both upregulation and downregulation of AQP4 expression is associated with brain pathology, over expression of AQP4 is one of the chief contributors of water imbalance in brain during ischemic pathology. We have found that Piroxicam binds to AQP4 with optimal binding energy value. Thus, we hypothesized that Piroxicam is neuroprotective in the rodent cerebral ischemic model by mitigating cerebral edema via AQP4 regulation.
  
  
  METHODS
  Rats were treated with Piroxicam OR placebo at 30 min prior, 2 h post and 4 h post 60 minutes of MCAO followed by 24 hour reperfusion. Rats were evaluated for neurological deficits and motor function just before sacrifice. Brains were harvested for infarct size estimation, water content measurement, biochemical analysis, RT-PCR and western blot experiments.
  
  
  RESULTS
  Piroxicam pretreatment thirty minutes prior to ischemia and four hour post reperfusion afforded neuroprotection as evident through significant reduction in cerebral infarct volume, improvement in motor behavior, neurological deficit and reduction in brain edema. Furthermore, ischemia induced surge in levels of nitrite and malondialdehyde were also found to be significantly reduced in ischemic brain regions in treated animals. This neuroprotection was found to be associated with inhibition of acid mediated rise in intracellular calcium levels and also downregulated AQP4 expression.
  
  
  CONCLUSIONS
  Findings of the present study provide significant evidence that Piroxicam acts as a potent AQP4 regulator and renders neuroprotection in focal cerebral ischemia. Piroxicam could be clinically exploited for the treatment of brain stroke along with other anti-stroke therapeutics in future.
authors.affiliation: School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi, (U.P.), India ; Department of Neurology, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, United States of America.
authors.forename: Pallab
authors.initials: P
authors.lastname: Bhattacharya
authors.forename: Anand Kumar
authors.initials: AK
authors.lastname: Pandey
authors.forename: Sudip
authors.initials: S
authors.lastname: Paul
authors.forename: Ranjana
authors.initials: R
authors.lastname: Patnaik
authors.forename: Dileep R
authors.initials: DR
authors.lastname: Yavagal
mesh_terms: D000818:Animals; D051401:Aquaporin 4 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D001929:Brain Edema / Q000150:complications; D020520:Brain Infarction / Q000150:complications; D002545:Brain Ischemia / Q000150:complications*; D002118:Calcium / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009573:Nitrites / Q000378:metabolism; D010894:Piroxicam / Q000494:pharmacology*; D051381:Rats; D015427:Reperfusion Injury / Q000150:complications / Q000378:metabolism* / Q000517:prevention & control*; D045442:Rotarod Performance Test; D020521:Stroke / Q000150:complications
chemical_list: D051401:Aquaporin 4; D018696:Neuroprotective Agents; D009573:Nitrites; D010894:Piroxicam; D008315:Malondialdehyde; D002118:Calcium
references.citation: FASEB J. 2001 Jan;15(1):2-4
references.pmid: 11099482
references.citation: Nihon Juigaku Zasshi. 1990 Dec;52(6):1281-3
references.pmid: 2287135
references.citation: Stroke. 2007 Feb;38(2):245-8
references.pmid: 17204668
references.citation: J Am Pharm Assoc Am Pharm Assoc. 1957 Mar;46(3):208-9
references.pmid: 13502156
references.citation: J Neurochem. 2001 Jan;76(2):480-9
references.pmid: 11208911
references.citation: Adv Exp Med Biol. 1993;337:191-5
references.pmid: 8109401
references.citation: FASEB J. 1987 Nov;1(5):358-64
references.pmid: 2824268
references.citation: Stroke. 1999 Dec;30(12):2704-12; discussion 2712
references.pmid: 10583001
references.citation: Behav Brain Res. 2008 May 16;189(1):65-74
references.pmid: 18243354
references.citation: Stroke. 2009 Jun;40(6):2182-90
references.pmid: 19372455
references.citation: J Neurophysiol. 2002 May;87(5):2555-61
references.pmid: 11976391
references.citation: Proc Natl Acad Sci U S A. 1998 Sep 29;95(20):11981-6
references.pmid: 9751776
references.citation: Anal Biochem. 1976 May 7;72:248-54
references.pmid: 942051
references.citation: Clin Chim Acta. 1998 Jun 22;274(2):177-88
references.pmid: 9694586
references.citation: Stroke. 1989 Jan;20(1):84-91
references.pmid: 2643202
references.citation: J Neurochem. 2008 Jul;106(1):429-41
references.pmid: 18410516
references.citation: Drug Discov Today. 2006 Aug;11(15-16):681-93
references.pmid: 16846795
references.citation: Proc Natl Acad Sci U S A. 2006 Sep 5;103(36):13532-6
references.pmid: 16938871
references.citation: Biochem Pharmacol. 2002 Jan 15;63(2):163-70
references.pmid: 11841790
references.citation: Mt Sinai J Med. 2002 Sep;69(4):242-8
references.pmid: 12357265
references.citation: Physiol Rev. 1979 Jul;59(3):527-605
references.pmid: 37532
references.citation: Stroke. 1993 Nov;24(11):1709-16
references.pmid: 7694393
references.citation: Brain Res Mol Brain Res. 2005 Jun 13;137(1-2):119-25
references.pmid: 15950769
references.citation: Methods Enzymol. 1984;105:138-47
references.pmid: 6727662
references.citation: Prog Neuropsychopharmacol Biol Psychiatry. 2002 Jun;26(5):871-7
references.pmid: 12369259
references.citation: Proc Natl Acad Sci U S A. 2003 Feb 18;100(4):2106-11
references.pmid: 12578959
references.citation: Free Radic Biol Med. 1994 Feb;16(2):195-200
references.pmid: 8005514
references.citation: J Cereb Blood Flow Metab. 1996 Jul;16(4):605-11
references.pmid: 8964799
references.citation: Med Hypotheses. 2012 Sep;79(3):352-7
references.pmid: 22795752
references.citation: Ann Neurol. 1982 May;11(5):491-8
references.pmid: 7103425
references.citation: Neurology. 2002 Jan 8;58(1):133-5
references.pmid: 11781420
references.citation: Anal Biochem. 1982 Nov 15;127(1):178-82
references.pmid: 7165085
references.citation: Med Hypotheses. 2012 Sep;79(3):393-5
references.pmid: 22771072
references.citation: Neuroscience. 2004;129(4):947-55
references.pmid: 15561410
references.citation: Acta Pharmacol Sin. 2004 Jan;25(1):90-7
references.pmid: 14704128
references.citation: Neuroscience. 2004;129(4):983-91
references.pmid: 15561413
references.citation: Neurosci Lett. 2011 Jan 13;488(1):60-4
references.pmid: 21056621
references.citation: Nat Med. 2000 Feb;6(2):159-63
references.pmid: 10655103
references.citation: Hippocampus. 2006;16(10):814-25
references.pmid: 16892187
references.citation: Brain Res. 1982 May 6;239(1):57-69
references.pmid: 7093691
references.citation: Stroke. 1989 Jul;20(7):925-9
references.pmid: 2501915
references.citation: Nat New Biol. 1971 Jun 23;231(25):232-5
references.pmid: 5284360
references.citation: Life Sci. 2004 Dec 17;76(5):573-83
references.pmid: 15556169
references.citation: Neuroscience. 2008 Jul 17;154(4):1458-66
references.pmid: 18555616
references.citation: J Neurosci Res. 2006 May 15;83(7):1231-40
references.pmid: 16511868
references.citation: Neurochem Res. 2005 Jan;30(1):39-46
references.pmid: 15756931
references.citation: Chin Med J (Engl). 2008 Dec 20;121(24):2572-7
references.pmid: 19187598
references.citation: Drugs Aging. 2007;24(7):537-46
references.pmid: 17658905
references.citation: Age (Dordr). 2013 Feb;35(1):59-67
references.pmid: 22057895
references.citation: Proc Natl Acad Sci U S A. 2003 Nov 11;100(23):13632-7
references.pmid: 14581618
references.citation: Stroke. 1996 Jun;27(6):1124-9
references.pmid: 8650725
references.citation: J Neurosurg. 2003 Apr;98(4):860-6
references.pmid: 12691413
references.citation: Eur J Pharmacol. 2003 Apr 25;467(1-3):103-9
references.pmid: 12706462
references.citation: Biochim Biophys Acta. 2006 Aug;1758(8):1085-93
references.pmid: 16564496
references.citation: Neurosci Lett. 2000 Aug 11;289(3):201-4
references.pmid: 10961664
references.citation: J Neurosci Res. 2005 Nov 15;82(4):458-64
references.pmid: 16237719
references.citation: PLoS One. 2009;4(3):e4764
references.pmid: 19274095