Testosterone has been shown to worsen histological and neurological impairment during cerebral ischemia in animal models. Cell culture studies revealed that testosterone is implicated in protecting neural and glial cells against insults, and they started to elucidate testosterone pathways that underlie these protective effects. These studies support the hypothesis that testosterone can be neuroprotective throughout an episode of cerebral ischemia. Therefore, we evaluated the mechanisms underlying the shift between testosterone protective and deleterious effects via block testosterone aromatization and androgen receptors in rats subjected to 60-minute middle cerebral artery occlusion. Fifty rats were divided into five equal groups: gonadally intact male; castrated male; intact male？+？flutamide; intact male？+？letrozole; intact male？+？combination flutamide and letrozole. Our results indicated that castration has the ability to reduce histological damage and to improve neurological score 24 hours after middle cerebral artery occlusion. Moreover, flutamide improved histologic and neurological impairment better than castration. Letrozole induced increases in striatal infarct volume and seizures in gonadally intact rats. Combination of flutamide and letrozole showed that letrozole can reverse beneficial effects of flutamide. In conclusion, it seems that the beneficial effects of flutamide are the prevention of the deleterious effects and enhancement of neuroprotective effects of testosterone during cerebral ischemia. 1. Introduction Stroke is a great reason of disability and death throughout the world [1]. Nowadays treatments are not very effective to reduce brain ischemia, whereas size of the infarct area will affect on patient’s chance of recovery from a stroke and it will keep growing if treatments are not appropriate [1–4]. So, for reducing damage we need to find more effective treatments. Among risk factors, sex has prominent role in stroke [5–8]. Epidemiological studies have shown that overall incidence of stroke is higher in men relative to age-matched women in most countries [9–12]. Present evidence suggests that mechanisms of cell death and neuroprotection are not similar and equal in males and females [9, 13, 14]. A large part of this difference between sexes is attributed to sex steroids [14–18]. Previous studies demonstrate that estrogen and progesterone give protection against cerebral ischemia by several mechanisms [19–23]. On the other hand, data about androgens are sparse and controversial [9, 18, 24, 25]. Human studies suggested male
References
[1]
S. H. Park, J. H. Kim, S. J. Park et al., “Protective effect of hexane extracts of Uncaria sinensis against photothrombotic ischemic injury in mice,” Journal of Ethnopharmacology, vol. 138, no. 3, pp. 774–779, 2011.
[2]
M. Sakurazawa, K.-I. Katsura, M. Saito, S. Asoh, S. Ohta, and Y. Katayama, “Mild hypothermia enhanced the protective effect of protein therapy with transductive anti-death FNK protein using a rat focal transient cerebral ischemia model,” Brain Research, vol. 1430, pp. 86–92, 2012.
[3]
N. Suzuki, M. Suzuki, K. Murakami, K. Hamajo, T. Tsukamoto, and M. Shimojo, “Cerebroprotective effects of TAK-937, a cannabinoid receptor agonist, on ischemic brain damage in middle cerebral artery occluded rats and non-human primates,” Brain Research, vol. 1430, pp. 93–100, 2012.
[4]
A. Dávalos, J. Alvarez-Sabín, J. Castillo et al., “Citicoline in the treatment of acute ischaemic stroke: an international, randomised, multicentre, placebo-controlled study (ICTUS trial),” The Lancet, vol. 380, no. 9839, pp. 349–357, 2012.
[5]
R. L. Sacco, “Newer risk factors for stroke,” Neurology, vol. 57, no. 5, supplement 2, pp. S31–S34, 2001.
[6]
R. X. You, J. J. McNeil, H. M. O'Malley, S. M. Davis, A. G. Thrift, and G. A. Donnan, “Risk factors for stroke due to cerebral infarction in young adults,” Stroke, vol. 28, no. 10, pp. 1913–1918, 1997.
[7]
A. J. Grau, C. Weimar, F. Buggle et al., “Risk factors, outcome, and treatment in subtypes of ischemic stroke: the German stroke data bank,” Stroke, vol. 32, no. 11, pp. 2559–2566, 2001.
[8]
R. L. Sacco, R. Adams, G. Albers et al., “Guidelines for prevention of stroke in patients with ischemic stroke or transient ischemic attack: a statement for healthcare professionals from the American heart association/American stroke association council on stroke—co-sponsored by the council on cardiovascular radiology and intervention. The American academy of neurology affirms the value of this guideline,” Stroke, vol. 37, no. 2, pp. 577–617, 2006.
[9]
K. Vagnerova, I. P. Koerner, and P. D. Hurn, “Gender and the injured brain,” Anesthesia and Analgesia, vol. 107, no. 1, pp. 201–214, 2008.
[10]
V. Caso, M. Paciaroni, G. Agnelli et al., “Gender differences in patients with acute ischemic stroke,” Women's Health, vol. 6, no. 1, pp. 51–57, 2010.
[11]
C. C. Beal, “Gender and stroke symptoms: a review of the current literature,” Journal of Neuroscience Nursing, vol. 42, no. 2, pp. 80–87, 2010.
[12]
P. Appelros, B. Stegmayr, and A. Terent, “Sex differences in stroke epidemiology: a systematic review,” Stroke, vol. 40, no. 4, pp. 1082–1090, 2009.
[13]
M. Yuan, C. Siegel, Z. Zeng, J. Li, F. Liu, and L. D. McCullough, “Sex differences in the response to activation of the poly (ADP-ribose) polymerase pathway after experimental stroke,” Experimental Neurology, vol. 217, no. 1, pp. 210–218, 2009.
[14]
P. D. Hurn, S. J. Vannucci, and H. Hagberg, “Adult or perinatal brain injury: does sex matter?” Stroke, vol. 36, no. 2, pp. 193–195, 2005.
[15]
P. D. Hurn and L. M. Brass, “Estrogen and stroke: a balanced analysis,” Stroke, vol. 34, no. 2, pp. 338–341, 2003.
[16]
P. D. Hurn and I. M. Macrae, “Estrogen as a neuroprotectant in stroke,” Journal of Cerebral Blood Flow and Metabolism, vol. 20, no. 4, pp. 631–652, 2000.
[17]
T. Hawk, Y. Q. Zhang, G. Rajakumar, A. L. Day, and J. W. Simpkins, “Testosterone increases and estradiol decreases middle cerebral artery occlusion lesion size in male rats,” Brain Research, vol. 796, no. 1-2, pp. 296–298, 1998.
[18]
C. A. Hill and R. H. Fitch, “Sex differences in mechanisms and outcome of neonatal hypoxia-ischemia in rodent models: implications for sex-specific neuroprotection in clinical neonatal practice,” Neurology Research International, vol. 2012, Article ID 867531, 9 pages, 2012.
[19]
M. Liu, M. H. Kelley, P. S. Herson, and P. D. Hurn, “Neuroprotection of sex steroids,” Minerva Endocrinologica, vol. 35, no. 2, pp. 127–143, 2010.
[20]
G. E. Hoffman, I. Merchenthaler, and S. L. Zup, “Neuroprotection by ovarian hormones in animal models of neurological disease,” Endocrine, vol. 29, no. 2, pp. 217–231, 2006.
[21]
S. Suzuki, C. M. Brown, and P. M. Wise, “Mechanisms of neuroprotection by estrogen,” Endocrine, vol. 29, no. 2, pp. 209–215, 2006.
[22]
V. R. Feeser and R. M. Loria, “Modulation of traumatic brain injury using progesterone and the role of glial cells on its neuroprotective actions,” Journal of Neuroimmunology, vol. 237, no. 1-2, pp. 4–12, 2011.
[23]
C. L. Gibson, B. Coomber, and J. Rathbone, “Is progesterone a candidate neuroprotective factor for treatment following ischemic stroke?” Neuroscientist, vol. 15, no. 4, pp. 324–332, 2009.
[24]
J. S. Janowsky, “The role of androgens in cognition and brain aging in men,” Neuroscience, vol. 138, no. 3, pp. 1015–1020, 2006.
[25]
T. M. Beer, L. B. Bland, J. R. Bussiere et al., “Testosterone loss and estradiol administration modify memory in men,” Journal of Urology, vol. 175, no. 1, pp. 130–135, 2006.
[26]
S. H. Yang, E. Perez, J. Cutright et al., “Testosterone increases neurotoxicity of glutamate in vitro and ischemia-reperfusion injury in an animal model,” Journal of Applied Physiology, vol. 92, no. 1, pp. 195–201, 2002.
[27]
J. W. Gatson and M. Singh, “Activation of a membrane-associated androgen receptor promotes cell death in primary cortical astrocytes,” Endocrinology, vol. 148, no. 5, pp. 2458–2464, 2007.
[28]
J. Cheng, N. J. Alkayed, and P. D. Hurn, “Deleterious effects of dihydrotestosterone on cerebral ischemic injury,” Journal of Cerebral Blood Flow and Metabolism, vol. 27, no. 9, pp. 1553–1562, 2007.
[29]
Y. Pan, H. Zhang, A. B. Acharya, P. H. Patrick, D. Oliver, and J. E. Morley, “Effect of testosterone on functional recovery in a castrate male rat stroke model,” Brain Research, vol. 1043, no. 1-2, pp. 195–204, 2005.
[30]
S. H. Yang, R. Liu, Y. Wen et al., “Neuroendocrine mechanism for tolerance to cerebral ischemia-reperfusion injury in male rats,” Journal of Neurobiology, vol. 62, no. 3, pp. 341–351, 2005.
[31]
S. M. Meusburger and J. R. Keast, “Testosterone and nerve growth factor have distinct but interacting effects on structure and neurotransmitter expression of adult pelvic ganglion cells in vitro,” Neuroscience, vol. 108, no. 2, pp. 331–340, 2001.
[32]
E. Ahlbom, “Androgen treatment of neonatal rats decreases susceptibility of cerebellar granule neurons to oxidative stress in vitro,” European Journal of Neuroscience, vol. 11, no. 4, pp. 1285–1291, 1999.
[33]
E. Ahlbom, G. S. Prins, and S. Ceccatelli, “Testosterone protects cerebellar granule cells from oxidative stress-induced cell death through a receptor mediated mechanism,” Brain Research, vol. 892, no. 2, pp. 255–262, 2001.
[34]
J. Hammond, Q. Le, C. Goodyer, M. Gelfand, M. Trifiro, and A. LeBlanc, “Testosterone-mediated neuroprotection through the androgen receptor in human primary neurons,” Journal of Neurochemistry, vol. 77, no. 5, pp. 1319–1326, 2001.
[35]
C. J. Pike, “Testosterone attenuates β-amyloid toxicity in cultured hippocampal neurons,” Brain Research, vol. 919, no. 1, pp. 160–165, 2001.
[36]
V. Chisu, P. Manca, G. Lepore, S. Gadau, M. Zedda, and V. Farina, “Testosterone induces neuroprotection from oxidative stress. Effects on catalase activity and 3-nitro-L-tyrosine incorporation into α-tubulin in a mouse neuroblastoma cell line,” Archives Italiennes de Biologie, vol. 144, no. 2, pp. 63–73, 2006.
[37]
A. Caruso, V. Di Giorgi Gerevini, M. Castiglione et al., “Testosterone amplifies excitotoxic damage of cultured oligodendrocytes,” Journal of Neurochemistry, vol. 88, no. 5, pp. 1179–1185, 2004.
[38]
C. J. Pike, T. V. V. Nguyen, M. Ramsden, M. Yao, M. P. Murphy, and E. R. Rosario, “Androgen cell signaling pathways involved in neuroprotective actions,” Hormones and Behavior, vol. 53, no. 5, pp. 693–705, 2008.
[39]
J. T. Lang and L. D. McCullough, “Pathways to ischemic neuronal cell death: are sex differences relevant?” Journal of Translational Medicine, vol. 6, article 33, 2008.
[40]
A. Vakili, F. Hosseinzadeh, and T. Sadogh, “Effect of aminoguanidine on post-ischemic brain edema in transient model of focal cerebral ischemia,” Brain Research, vol. 1170, pp. 97–102, 2007.
[41]
B. Sun, L. Chen, X. Wei, Y. Xiang, X. Liu, and X. Zhang, “The Akt/GSK-3β pathway mediates flurbiprofen-induced neuroprotection against focal cerebral ischemia/reperfusion injury in rats,” Biochemical and Biophysical Research Communications, vol. 409, no. 4, pp. 808–813, 2011.
[42]
H. Ji, J. Miao, X. Zhang et al., “Inhibition of sonic hedgehog signaling aggravates brain damage associated with the down-regulation of Gli1, Ptch1 and SOD1 expression in acute ischemic stroke,” Neuroscience Letters, vol. 506, no. 1, pp. 1–6, 2012.
[43]
R. Noor, C. X. Wang, and A. Shuaib, “Hyperthermia masks the neuroprotective effects of tissue plaminogen activator,” Stroke, vol. 36, no. 3, pp. 665–669, 2005.
[44]
R. A. Swanson, M. T. Morton, G. Tsao-Wu, R. A. Savalos, C. Davidson, and F. R. Sharp, “A semiautomated method for measuring brain infarct volume,” Journal of Cerebral Blood Flow and Metabolism, vol. 10, no. 2, pp. 290–293, 1990.
[45]
M. Uchida, J. M. Palmateer, P. S. Herson, A. C. DeVries, J. Cheng, and P. D. Hurn, “Dose-dependent effects of androgens on outcome after focal cerebral ischemia in adult male mice,” Journal of Cerebral Blood Flow and Metabolism, vol. 29, no. 8, pp. 1454–1462, 2009.
[46]
W. Zhu, L. Wang, L. Zhang et al., “Isoflurane preconditioning neuroprotection in experimental focal stroke is androgen-dependent in male mice,” Neuroscience, vol. 169, no. 2, pp. 758–769, 2010.
[47]
L. L. Jeppesen, H. S. J？rgensen, H. Nakayama, H. O. Raaschou, T. S. Olsen, and K. Winther, “Decreased serum testosterone in men with acute ischemic stroke,” Arteriosclerosis, Thrombosis, and Vascular Biology, vol. 16, no. 6, pp. 749–754, 1996.
[48]
T. J. K. Toung, R. J. Traystman, and P. D. Hurn, “Estrogen-mediated neuroprotection after experimental stroke in male rats,” Stroke, vol. 29, no. 8, pp. 1666–1670, 1998.
[49]
R. Orlando, A. Caruso, G. Molinaro et al., “Nanomolar concentrations of anabolic-androgenic steroids amplify excitotoxic neuronal death in mixed mouse cortical cultures,” Brain Research, vol. 1165, no. 1, pp. 21–29, 2007.
[50]
Y. Zhang, N. Champagne, L. K. Beitel, C. G. Goodyer, M. Trifiro, and A. LeBlanc, “Estrogen and androgen protection of human neurons against intracellular amyloid β1-42 toxicity through heat shock protein 70,” Journal of Neuroscience, vol. 24, no. 23, pp. 5315–5321, 2004.
[51]
C. A. Berrevoets, A. Umar, and A. O. Brinkmann, “Antiandrogens: selective androgen receptor modulators,” Molecular and Cellular Endocrinology, vol. 198, no. 1-2, pp. 97–103, 2002.
[52]
B. Haendler and A. Cleve, “Recent developments in antiandrogens and selective androgen receptor modulators,” Molecular and Cellular Endocrinology, vol. 352, no. 1-2, pp. 79–91, 2012.
[53]
T. V. V. Nguyen, M. Yao, and C. J. Pike, “Flutamide and cyproterone acetate exert agonist effects: induction of androgen receptor-dependent neuroprotection,” Endocrinology, vol. 148, no. 6, pp. 2936–2943, 2007.
[54]
C. I. Wong, W. R. Kelce, M. Sar, and E. M. Wilson, “Androgen receptor antagonist versus agonist activities of the fungicide vinclozolin relative to hydroxyflutamide,” The Journal of Biological Chemistry, vol. 270, no. 34, pp. 19998–20003, 1995.
[55]
L. M. Garcia-Segura, “Aromatase in the brain: not just for reproduction anymore,” Journal of Neuroendocrinology, vol. 20, no. 6, pp. 705–712, 2008.
[56]
H. V. O. Carswell, A. F. Dominiczak, L. M. Garcia-Segura, N. Harada, J. B. Hutchison, and I. M. Macrae, “Brain aromatase expression after experimental stroke: topography and time course,” Journal of Steroid Biochemistry and Molecular Biology, vol. 96, no. 1, pp. 89–91, 2005.
[57]
L. Zhou, N. Lehan, U. Wehrenberg et al., “Neuroprotection by estradiol: a role of aromatase against spine synapse loss after blockade of GABAA receptors,” Experimental Neurology, vol. 203, no. 1, pp. 72–81, 2007.
[58]
A. Arboix, E. Comes, L. García-Eroles, J. B. Massons, M. Oliveres, and M. Balcells, “Prognostic value of very early seizures for in-hospital mortality in atherothrombotic infarction,” European Neurology, vol. 50, no. 2, pp. 78–84, 2003.
