Neuroprotective activity of tamoxifen in permanent focal ischemia

Restricted access

Object. The authors have previously shown that tamoxifen is effective in protecting brain tissue from ischemic injury in a rat model of reversible focal ischemia. In this study the authors tested whether similar protective effects are found in a rat model of permanent focal ischemia (permanent middle cerebral artery [MCA] occlusion).

Methods. Tamoxifen (20 mg/kg) was given either before or at 1, 3, or 6 hours after permanent MCA occlusion in rats, with sustaining doses given every 12 hours thereafter. The median infarct volume measured after 72 hours was 113 mm3 for the vehicle (dimethyl sulfoxide) groups, compared with 31 mm3 for pretreatment, and 14, 27, and 98 mm3 for treatment beginning at 1, 3, and 6 hours, respectively, after permanent MCA occlusion. The infarct reductions in the pretreated and 1- and 3-hour post—MCA occlusion treatment groups were statistically significant (p < 0.05). At 3 hours after permanent MCA occlusion, tamoxifen also significantly reduced the infarct size at a lower dose of 5 mg/kg but not at 1 mg/kg; the same sustaining doses of 5 and 1 mg/kg were given every 12 hours.

Conclusions. Tamoxifen is as effective in a permanent model of focal ischemia as it is in the reversible model, and the therapeutic window of 3 hours after initiation of ischemia is identical. This effectiveness is likely due to several properties of the drug, including its known ability to cross the blood—brain barrier. Because tamoxifen has been administered safely in humans for treatment of gliomas at similarly high doses to those used in this study, it may be clinically useful as a treatment for ischemic stroke.

Article Information

Address reprint requests to: Harold K. Kimelberg, Ph.D., Division of Neurosurgery, A-60, Albany Medical College, 47 New Scotland Avenue, Albany, New York 12208. email:

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Box plot showing time window for effects of tamoxifen on infarct volume measured using TTC 72 hours after permanent MCA occlusion (pMCAo). The times shown on the abscissa refer to the start of tamoxifen administration (20 mg/kg), measured from initiation of MCA occlusion; “pre-pMCAo” refers to animals infused with 20 mg/kg tamoxifen over a period of 15 minutes beginning 25 minutes before the start of ischemia. The boxes labeled 1 hour, 3 hour, and 6 hour pMCAo show infarct volumes measured in animals that received vehicle or 20 mg/kg tamoxifen starting at 1, 3, or 6 hours, respectively, after permanent MCA occlusion. As described in detail in Materials and Methods, the first two doses, for pretreatment and 1 hour after MCA occlusion, were given intravenously, whereas in the 3- and 6-hour permanent MCA occlusion groups all doses were administered intraperitoneally. All animals received additional 20-mg/kg intraperitoneal injections at 12-hour intervals measured from the first dose until death. The vehicle (control) groups received dimethyl sulfoxide injected at the same times via the same routes but are combined here for clarity and because there were no statistically significant differences among them. Box plots show the median value (horizontal line in box), and the interquartile range (25–75%) is represented by the box. Whiskers encompass the 5 to 95% range and the black squares indicate the means. Values from individual animals are plotted to the right of the box plots. *p < 0.05 compared with corresponding vehicle-treated controls (Mann—Whitney U-test).

  • View in gallery

    Photographs of representative slices of rat brain stained with TTC for determination of infarct volume in a vehicle-treated animal (upper) and an animal receiving 20 mg/kg tamoxifen intravenously before MCA occlusion and intraperitoneally at 12-hour intervals thereafter (lower). The unstained (white) area in the cortex indicates the area of infarction.

  • View in gallery

    Box plot showing effect of tamoxifen given intraperitoneally at doses of 1, 5, and 20 mg/kg 3 hours after permanent MCA occlusion with the same dose given intraperitoneally every 12 hours until death, on infarct size measured at 72 hours. Tamoxifen significantly reduces the volume of infarction at 5 mg/kg (*p < 0.05, Mann—Whitney U-test), as well as at 20 mg/kg (the 20 mg/kg data are the same as in Fig. 1).



Ahotupa MMantyla EKangas L: Antioxidant properties of the triphenylethylene antiestrogen drug toremifene. Naunyn Schmiedebergs Arch Pharmacol 356:2973021997Naunyn Schmiedebergs Arch Pharmacol 356:


Bederson JBPitts LHGermano SMet al: Evaluation of 2,3,5-triphenyltetrazolium chloride as a stain for detection and quantification of experimental cerebral infarction in rats. Stroke 17:130413081986Stroke 17:


Bederson JBPitts LHTsuji Met al: Rat middle cerebral artery occlusion: evaluation of the model and development of a neurologic examination. Stroke 17:4724761986Stroke 17:


Belayev LAlonso OFBusto Ret al: Middle cerebral artery occlusion in the rat by intraluminal suture. Neurological and pathological evaluation of an improved model. Stroke 27:161616231996Stroke 27:


Biegon ABrewster MDegani Het al: A permanently charged tamoxifen derivative displays anticancer activity and improved tissue selectivity in rodents. Cancer Res 56:432843311996Cancer Res 56:


Busto RDietrich WDGlobus MYet al: Small differences in intraischemic brain temperature critically determine the extent of ischemic neuronal injury. J Cereb Blood Flow Metab 7:7297381987J Cereb Blood Flow Metab 7:


Choi DW: Excitotoxic cell death. J Neurobiol 23:126112761992Choi DW: Excitotoxic cell death. J Neurobiol 23:


del Zoppo GJ: Clinical trials in acute stroke: why have they not been successful? Neurology 51 (Suppl 3):S59S611998del Zoppo GJ: Clinical trials in acute stroke: why have they not been successful? Neurology 51 (Suppl 3):


Dubey RKTyurina YYTyurin VAet al: Estrogen and tamoxifen metabolites protect smooth muscle cell membrane phospholipids against peroxidation and inhibit cell growth. Circ Res 84:2292391999Circ Res 84:


el-Sabban FReid KHZhang YPet al: Stability of thrombosis induced by electrocoagulation of rat middle cerebral artery. Stroke 25:224122451994Stroke 25:


Fox GGallacher DShevde Set al: Anatomic variation of the middle cerebral artery in the Sprague-Dawley rat. Stroke 24:208720931993Stroke 24:


Friedman ZY: Recent advances in understanding the molecular mechanisms of tamoxifen action. Cancer Invest 16:3913961998Friedman ZY: Recent advances in understanding the molecular mechanisms of tamoxifen action. Cancer Invest 16:


Ginsberg MD: Neuroprotection in brain ischemia: an update (Part I). Neuroscientist 1:951031995Ginsberg MD: Neuroprotection in brain ischemia: an update (Part I). Neuroscientist 1:


Ginsberg MD: Neuroprotection in brain ischemia: an update (Part II). Neuroscientist 1:1641751995Ginsberg MD: Neuroprotection in brain ischemia: an update (Part II). Neuroscientist 1:


Harukuni ITraystman RJKirsch JR: Effect of AR-R 17477, a potent neuronal nitric oxide synthase inhibitor, on infarction volume resulting from permanent focal ischemia in rats. Crit Care Med 27:250825111999Crit Care Med 27:


Isayama KPitts LHNishimura MC: Evaluation of 2,3,5-triphenyltetrazolium chloride staining to delineate rat brain infarcts. Stroke 22:139413981991Stroke 22:


Kimelberg HKFeustel PJJin Yet al: Acute treatment with tamoxifen reduces ischemic damage following middle cerebral artery occlusion. Neuroreport 11:267526792000Neuroreport 11:


Kirk JKirk K: Inhibition of volume-activated I-and taurine efflux from HeLa cells by P-glycoprotein blockers correlates with calmodulin inhibition. J Biol Chem 269:29389293941994J Biol Chem 269:


Lien EASolheim EUeland PM: Distribution of tamoxifen and its metabolites in rat and human tissues during steady-state treatment. Cancer Res 51:483748441991Cancer Res 51:


MacGregor JIJordan VC: Basic guide to the mechanisms of antiestrogen action. Pharmacol Rev 50:1511961998Pharmacol Rev 50:


Mehta SHDhandapani KMWebb RCet al: Therapeutic doses of tamoxifen exert neuroprotective effects in acute ischaemic stroke. Soc Neurosci Abstracts 27:2262001 (Abstract)Soc Neurosci Abstracts 27:


Menzies SAHoff JTBetz AL: Middle cerebral artery occlusion in rats: a neurological and pathological evaluation of a reproducible model. Neurosurgery 31:1001071992Neurosurgery 31:


Obata TKubota S: Protective effect of tamoxifen on 1-methyl-4-phenylpyridine-induced hydroxyl radical generation in the rat striatum. Neurosci Lett 308:87902001Neurosci Lett 308:


Osuka KFeustel PJMongin AAet al: Tamoxifen inhibits nitrotyrosine formation after reversible middle cerebral artery occlusion in the rat. J Neurochem 76:184218502001J Neurochem 76:


Phillis JWSong DO'Regan MH: Tamoxifen, a chloride channel blocker, reduces glutamate and aspartate release from the ischemic cerebral cortex. Brain Res 780:3523551998Brain Res 780:


Renodon ABoucher JLSari MAet al: Strong inhibition of neuronal nitric oxide synthase by the calmodulin antagonist and anti-estrogen drug tamoxifen. Biochem Pharmacol 54:110911141997Biochem Pharmacol 54:


Rutledge EMAschner MKimelberg HK: Pharmacological characterization of swelling-induced D-[3H]aspartate release from primary astrocyte cultures. Am J Physiol 274:C1511C15201998Am J Physiol 274:


Seki YFeustel PJKeller RW Jret al: Inhibition of ischemia-induced glutamate release in rat striatum by dihydrokinate and an anion channel blocker. Stroke 30:4334401999Stroke 30:


Siesjo BKKatsura KIZhao Qet al: Mechanisms of secondary brain damage in global and focal ischemia: a speculative synthesis. J Neurotrauma 12:9439561995J Neurotrauma 12:


Simpkins JWRajakumar GZhang YQet al: Estrogens may reduce motality and ischemic damage caused by middle cerebral artery occlusion in the female rat. J Neurosurg 87:7247301997J Neurosurg 87:


Strange KEmma FJackson PS: Cellular and molecular physiology of volume-sensitive anion channels. Am J Physiol Cell Physiol 270:C711C7301996Am J Physiol Cell Physiol 270:


Tamura AGraham DIMcCulloch Jet al: Focal cerebral ischaemia in the rat: 1. Description of technique and early neuropathological consequences following middle cerebral artery occlusion. J Cereb Blood Flow Metab 1:53601981J Cereb Blood Flow Metab 1:


Toung TJTraystman RJHurn PD: Estrogen-mediated neuroprotection after experimental stroke in male rats. Stroke 29:166616701998Stroke 29:


Viscoli CMBrass LMKernan WNet al: A clinical trial of estrogen-replacement therapy after ischemic stroke. N Engl J Med 345:124312492001N Engl J Med 345:


Wang QSantizo RBaughman VLet al: Estrogen provides neuroprotection in transient forebrain ischemia through perfusion-independent mechanisms in rats. Stroke 30:6306371999Stroke 30:


Wiseman H: Tamoxifen: new membrane-mediated mechanisms of action and therapeutic advances. Trends Pharmacol Sci 15:83891994Wiseman H: Tamoxifen: new membrane-mediated mechanisms of action and therapeutic advances. Trends Pharmacol Sci 15:




All Time Past Year Past 30 Days
Abstract Views 11 11 9
Full Text Views 85 85 23
PDF Downloads 69 69 23
EPUB Downloads 0 0 0


Google Scholar