Uric Acid and Neuroprotection
2008; Lippincott Williams & Wilkins; Volume: 39; Issue: 8 Linguagem: Inglês
10.1161/strokeaha.108.524462
ISSN1524-4628
Autores Tópico(s)Alcohol Consumption and Health Effects
ResumoHomeStrokeVol. 39, No. 8Uric Acid and Neuroprotection Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessLetterPDF/EPUBUric Acid and Neuroprotection Peter H. Proctor, PhD, MD Peter H. ProctorPeter H. Proctor Drugscom, Inc, Houston, Tex Originally published19 Jun 2008https://doi.org/10.1161/STROKEAHA.108.524462Stroke. 2008;39:e126Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: June 19, 2008: Previous Version 1 To the Editor:Having arguably originated both sides and after long-equivocation over whether urate is physiologically primarily pro- or antioxidant, we finally declared in favor of a neuroprotective role in acute ischemic stroke.1 But, as Dawson et al2 note, this leaves unanswered the role of xanthine oxidase and the putative pro-oxidant role of urate in atherosclerosis, metabolic syndrome, and so forth.3–6 Perhaps treatment will ultimately involve both allopurinol and urate.Besides the work of Chamorro and others, our support for an acute neuroprotective role is based on new evidence for specific regulation of urate levels, combined with a wider tissue-protective role. This includes activation of redox-sensitive glutamate transport elements such as glial EAAT-1 (review, ref 3), tying urate mechanistically to amelioration of excitotoxicity.This may partially explain the mismatch between animal and human trials with neuroprotectants. Essentially absent in animal models, arguably responsible for 60% to 70% of human plasma antioxidant activity, and with no treatment time lag, uric acid likely leaves much less therapeutic room for similar extracellular reducing antioxidants or (say) antiexcitotoxic agents in humans. Thus, the effectiveness of such agents in animals led to therapeutic dead ends.A more-directed approach to neuroprotection blocks the pro-oxidant effects of uric acid2–6 and/or xanthine oxidase,2 while augmenting urates' tissue-protective properties, eg, with superoxide dismutases (SODs).6 Similar examples include agents acting mitochondrially and/or across the blood-brain barrier. This first drew us to the spin-traps phenylbutylnitrone (PBN–the parent drug for the putative neuroprotectant NXY-059) and 2-methyl-2-nitrosopropane (MNP), as well as the SOD-mimetic spin-labels TEMPO and TEMPOL. As we note1 SOD itself is neuroprotectant, as are TEMPO/ TEMPOL. These agents have proven very nontoxic in human and animal trials. As "orgotein" or "ontosein," SOD itself gained regulatory approval in Europe for radiation cystitis and Peyronies disease. Likewise, TEMPOL is currently in clinical trials for radiation alopecia and parotiditis and for hypertension. A TEMPOL ester is also in trials for age-related macular degeneration.Similarly, Cutler and coworkers relate primate longevity to uric acid levels7and separately demonstrate8 that the action of PBN might be related to its hydrolysis products, especially the nitric oxide–releasing spin-trap tert-nitrosobutane, aka MNP. This was taken up by Ames and his coworkers,9 especially with MNPs reduced form, NtBHA. Previously, their rediscovery (a decade after our similar work10) of both the antioxidant properties of urate and its putative role as an evolutionary substitute for ascorbate made this scientifically respectable. In turn, we cite11 both group's PBN work in proposing that the positive results in SAINT-I were due to production of such products from NXY-059, a matter we shall shortly revisit.DisclosuresP.H.P. has certain patent claims to nitrone and nitroxide spin traps and spin-labels.1 Proctor PH. Uric acid: neuroprotective or neurotoxic? Stroke. 2008; 39: e88.LinkGoogle Scholar2 Dawson J, Quinn TJ, Walters MR. Response to Letter by Proctor. Stroke. 2008; 39: e89.LinkGoogle Scholar3 Kutzing MK, Firestein BL. Altered uric acid levels and disease states. J Pharmacol Exp Ther. 2008; 324: 1–7.MedlineGoogle Scholar4 Kanellis J, Johnson RJ. Elevated uric acid and ischemic stroke: accumulating evidence that it is injurious and not neuroprotective. Stroke. 2003; 34: 1956–1958.LinkGoogle Scholar5 Proctor PH. Free radicals, uric acid, and human disease. Free Radical Biol Med. 1996; 20: 761–762.MedlineGoogle Scholar6 Proctor PH, Kirkpatrick DS, McGinness JE. Superoxide-dismutase therapy in hyperuricaemic syndromes. Lancet. 1978; 8: 2: 95.Google Scholar7 Cutler RG. Urate and ascorbate: their possible roles as antioxidants in determining longevity of mammalian species. Arch Gerontol Geriatr. 1984; 3: 321–348.CrossrefMedlineGoogle Scholar8 WChamulitrat, SJJordan, RPMason, Saito K, Cutler RG. Nitric oxide formation during light-induced decomposition of phenyl N-tert-butylnitrone. J Biol Chem. 1993; 268: 11520–11527.MedlineGoogle Scholar9 Atamna H, Paler-Martínez A, Ames BN. N-t-butyl hydroxylamine, a hydrolysis product of -phenyl-n-t-butyl nitrone, is more potent in delaying senescence in human lung fibroblasts. J Biol Chem. 2000; 275: 6741–6748.CrossrefMedlineGoogle Scholar10 Proctor P. Uric acid and ascorbate: similar functions in man? Nature. 1970; 228: 868.Google Scholar11 Proctor PH, Tamborello LP. SAINT-I worked, but the neuroprotectant is not NXY-059. Stroke. 2007; 38: e109.LinkGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetailsCited By Huang S, Wang J, Fan D, Luo T, Li Y, Tu Y, Shen Y, Zeng G, Chen D, Wang Y, Chen L, Wang Y and Guo J (2022) The association of serum uric acid with cognitive impairment and ATN biomarkers, Frontiers in Aging Neuroscience, 10.3389/fnagi.2022.943380, 14 Bao L, Zhang Y, Zhang J, Gu L, Yang H, Huang Y, Xia N and Zhang H (2018) Urate inhibits microglia activation to protect neurons in an LPS-induced model of Parkinson's disease, Journal of Neuroinflammation, 10.1186/s12974-018-1175-8, 15:1, Online publication date: 1-Dec-2018. Bansal R and Singh R (2017) Exploring the potential of natural and synthetic neuroprotective steroids against neurodegenerative disorders: A literature review, Medicinal Research Reviews, 10.1002/med.21458, 38:4, (1126-1158), Online publication date: 1-Jul-2018. Yin P, Lv H, Li Y, Meng Y, Zhang L and Tang P (2017) The association between serum uric acid level and the risk of fractures: a systematic review and meta-analysis, Osteoporosis International, 10.1007/s00198-017-4059-3, 28:8, (2299-2307), Online publication date: 1-Aug-2017. Johnson N, Özkan M, Burgess A, Prokic E, Wafford K, O'Neill M, Greenhill S, Stanford I and Woodhall G (2017) Phase-amplitude coupled persistent theta and gamma oscillations in rat primary motor cortex in vitro, Neuropharmacology, 10.1016/j.neuropharm.2017.04.009, 119, (141-156), Online publication date: 1-Jun-2017. Morris G, Walder K, McGee S, Dean O, Tye S, Maes M and Berk M (2017) A model of the mitochondrial basis of bipolar disorder, Neuroscience & Biobehavioral Reviews, 10.1016/j.neubiorev.2017.01.014, 74, (1-20), Online publication date: 1-Mar-2017. 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August 2008Vol 39, Issue 8 Advertisement Article InformationMetrics https://doi.org/10.1161/STROKEAHA.108.524462PMID: 18566300 Originally publishedJune 19, 2008 PDF download Advertisement
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