Neuroprotective effect of an angiotensin receptor type 2 agonist following cerebral ischemia in vitro and in vivo
Intracerebral administration of the angiotensin II type 2 receptor (AT2R) agonist, CGP42112, is neuroprotective in a rat model of ischemic stroke. To explore further its possible cellular target(s) and therapeutic utility, we firstly examined whether CGP42112 may exert direct protective effects on primary neurons following glucose deprivation in vitro. Secondly, we tested whether CGP42112 is effective when administered systemically in a mouse model of cerebral ischemia.
Primary cortical neurons were cultured from E17 C57Bl6 mouse embryos for 9 d, exposed to glucose deprivation for 24 h alone or with drug treatments, and percent cell survival assessed using trypan blue exclusion. Ischemic stroke was induced in adult male C57Bl6 mice by middle cerebral artery occlusion for 30 min, followed by reperfusion for 23.5 h. Neurological assessment was performed and then mice were euthanized and infarct and edema volume were analysed.
During glucose deprivation, CGP42112 (1x10-8 M and 1x10-7 M) reduced cell death by ~30%, an effect that was prevented by the AT2R antagonist, PD123319 (1x10-6 M). Neuroprotection by CGP42112 was lost at a higher concentration (1x10-6 M) but was unmasked by co-application with the AT1R antagonist, candesartan (1x10-7 M). By contrast, Compound 21 (1x10-8 M to 1x10-6 M), a second AT2R agonist, had no effect on neuronal survival. Mice treated with CGP42112 (1 mg/kg i.p.) after cerebral ischemia had improved functional outcomes over vehicle-treated mice as well as reduced total and cortical infarct volumes.
These results indicate that CGP42112 can directly protect neurons from ischemia-like injury in vitro via activation of AT2Rs, an effect opposed by AT1R activation at high concentrations. Furthermore, systemic administration of CGP42112 can reduce functional deficits and infarct volume following cerebral ischemia in vivo.
- Zaleska MM, Mercado ML, Chavez J, Feuerstein GZ, Pangalos MN, Wood A: The development of stroke therapeutics: promising mechanisms and translational challenges. Neuropharmacology 2009, 56:329–341. CrossRef
- Rahman RMA, Nair SM, Appleton I: Current and future pharmacological interventions for the acute treatment of ischaemic stroke. Current Anaesthesia & Critical Care 2005, 16:99–109. CrossRef
- Dai WJ, Funk A, Herdegen T, Unger T, Culman J: Blockade of central angiotensin AT(1) receptors improves neurological outcome and reduces expression of AP-1 transcription factors after focal brain ischemia in rats. Stroke 1999, 30:2391–2398. discussion 2398–2399 CrossRef
- Ito T, Yamakawa H, Bregonzio C, Terron JA, Falcon-Neri A, Saavedra JM: Protection against ischemia and improvement of cerebral blood flow in genetically hypertensive rats by chronic pretreatment with an angiotensin II AT1 antagonist. Stroke 2002, 33:2297–2303. CrossRef
- Iwai M, Liu HW, Chen R, Ide A, Okamoto S, Hata R, Sakanaka M, Shiuchi T, Horiuchi M: Possible inhibition of focal cerebral ischemia by angiotensin II type 2 receptor stimulation. Circulation 2004, 110:843–848. CrossRef
- Iwanami J, Mogi M, Tsukuda K, Min LJ, Sakata A, Jing F, Ohshima K, Horiuchi M: Effect of angiotensin II type 2 receptor deletion in hematopoietic cells on brain ischemia-reperfusion injury. Hypertension 2011, 58:404–409. CrossRef
- Li J, Culman J, Hortnagl H, Zhao Y, Gerova N, Timm M, Blume A, Zimmermann M, Seidel K, Dirnagl U, Unger T: Angiotensin AT2 receptor protects against cerebral ischemia-induced neuronal injury. FASEB J 2005, 19:617–619.
- McCarthy CA, Vinh A, Callaway JK, Widdop RE: Angiotensin AT2 receptor stimulation causes neuroprotection in a conscious rat model of stroke. Stroke 2009, 40:1482–1489. CrossRef
- Mogi M, Li JM, Iwanami J, Min LJ, Tsukuda K, Iwai M, Horiuchi M: Angiotensin II type-2 receptor stimulation prevents neural damage by transcriptional activation of methyl methanesulfonate sensitive 2. Hypertension 2006, 48:141–148. CrossRef
- Schmerbach K, Schefe JH, Krikov M, Muller S, Villringer A, Kintscher U, Unger T, Thoene-Reineke C: Comparison between single and combined treatment with candesartan and pioglitazone following transient focal ischemia in rat brain. Brain Res 2008, 1208:225–233. CrossRef
- Gelosa P, Pignieri A, Fandriks L, de Gasparo M, Hallberg A, Banfi C, Castiglioni L, Turolo L, Guerrini U, Tremoli E, Sironi L: Stimulation of AT2 receptor exerts beneficial effects in stroke-prone rats: focus on renal damage. J Hypertens 2009, 27:2444–2451. CrossRef
- Ginsberg MD: Adventures in the pathophysiology of brain ischemia: penumbra, gene expression, neuroprotection: the 2002 Thomas Willis Lecture. Stroke 2003, 34:214–223. CrossRef
- Engelhorn T, Goerike S, Doerfler A, Okorn C, Forsting M, Heusch G, Schulz R: The angiotensin II type 1-receptor blocker candesartan increases cerebral blood flow, reduces infarct size, and improves neurologic outcome after transient cerebral ischemia in rats. J Cereb Blood Flow Metab 2004, 24:467–474. CrossRef
- Brdon J, Kaiser S, Hagemann F, Zhao Y, Culman J, Gohlke P: Comparison between early and delayed systemic treatment with candesartan of rats after ischaemic stroke. J Hypertens 2007, 25:187–196. CrossRef
- Jones ES, Vinh A, McCarthy CA, Gaspari TA, Widdop RE: AT2 receptors: functional relevance in cardiovascular disease. Pharmacol Ther 2008, 120:292–316. CrossRef
- Schrader J, Luders S, Kulschewski A, Berger J, Zidek W, Treib J, Einhaupl K, Diener HC, Dominiak P: The ACCESS Study: evaluation of Acute Candesartan Cilexetil Therapy in Stroke Survivors. Stroke 2003, 34:1699–1703. CrossRef
- Schrader J, Luders S, Kulschewski A, Hammersen F, Plate K, Berger J, Zidek W, Dominiak P, Diener HC: Morbidity and Mortality After Stroke, Eprosartan Compared with Nitrendipine for Secondary Prevention: principal results of a prospective randomized controlled study (MOSES). Stroke 2005, 36:1218–1226. CrossRef
- Unger T, Dahlof B: Compound 21, the first orally active, selective agonist of the angiotensin type 2 receptor (AT2): implications for AT2 receptor research and therapeutic potential. J Renin Angiotensin Aldosterone Syst 2010, 11:75–77. CrossRef
- Mattson MP, Barger SW, Begley JG, Mark RJ: Calcium, free radicals, and excitotoxic neuronal death in primary cell culture. Methods Cell Biol 1995, 46:187–216. CrossRef
- Acker T, Acker H: Cellular oxygen sensing need in CNS function: physiological and pathological implications. J Exp Biol 2004, 207:3171–3188. CrossRef
- Martin RL, Lloyd HG, Cowan AI: The early events of oxygen and glucose deprivation: setting the scene for neuronal death? Trends Neurosci 1994, 17:251–257. CrossRef
- Arumugam TV, Tang SC, Lathia JD, Cheng A, Mughal MR, Chigurupati S, Magnus T, Chan SL, Jo DG, Ouyang X, et al.: Intravenous immunoglobulin (IVIG) protects the brain against experimental stroke by preventing complement-mediated neuronal cell death. Proc Natl Acad Sci U S A 2007, 104:14104–14109. CrossRef
- Brait VH, Jackman KA, Walduck AK, Selemidis S, Diep H, Mast AE, Guida E, Broughton BR, Drummond GR, Sobey CG: Mechanisms contributing to cerebral infarct size after stroke: gender, reperfusion, T lymphocytes, and Nox2-derived superoxide. J Cereb Blood Flow Metab 2010, 30:1306–1317. CrossRef
- Jackman KA, Miller AA, Drummond GR, Sobey CG: Importance of NOX1 for angiotensin II-induced cerebrovascular superoxide production and cortical infarct volume following ischemic stroke. Brain Res 2009, 1286:215–220. CrossRef
- Bederson JB, Pitts LH, Tsuji M, Nishimura MC, Davis RL, Bartkowski H: Rat middle cerebral artery occlusion: evaluation of the model and development of a neurologic examination. Stroke 1986, 17:472–476. CrossRef
- Hattori K, Lee H, Hurn PD, Crain BJ, Traystman RJ, DeVries AC: Cognitive deficits after focal cerebral ischemia in mice. Stroke 2000, 31:1939–1944. CrossRef
- Macari D, Whitebread S, Cumin F, De Gasparo M, Levens N: Renal actions of the angiotensin AT2 receptor ligands CGP 42112 and PD 123319 after blockade of the renin-angiotensin system. Eur J Pharmacol 1994, 259:27–36. CrossRef
- Bosnyak S, Jones ES, Christopoulos A, Aguilar MI, Thomas WG, Widdop RE: Relative affinity of angiotensin peptides and novel ligands at AT1 and AT2 receptors. Clin Sci (Lond) 2011, 121:297–303.
- Reinecke K, Lucius R, Reinecke A, Rickert U, Herdegen T, Unger T: Angiotensin II accelerates functional recovery in the rat sciatic nerve in vivo: role of the AT2 receptor and the transcription factor NF-kappaB. FASEB J 2003, 17:2094–2096.
- McCarthy CA, Vinh A, Callaway JK, Widdop RE: Response to Letter by Tsuda. Stroke 2009, 40:e494. CrossRef
- Zhao Y, Rempe DA: Targeting astrocytes for stroke therapy. Neurotherapeutics 2010, 7:439–451. CrossRef
- Neuroprotective effect of an angiotensin receptor type 2 agonist following cerebral ischemia in vitro and in vivo
- Open Access
- Available under Open Access This content is freely available online to anyone, anywhere at any time.
Experimental & Translational Stroke Medicine
- Online Date
- August 2012
- Online ISSN
- BioMed Central
- Additional Links
- AT2 receptor
- Cerebral ischemia
- Glucose deprivation
- Neuronal death
- Author Affiliations
- 1. Department of Pharmacology, Monash University, Clayton, VIC, 3800, Australia
- 2. School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia