TY - JOUR
T1 - Neuroprotection by tamoxifen in focal cerebral ischemia is not mediated by an agonist action at estrogen receptors but is associated with antioxidant activity
AU - Zhang, Yonghua
AU - Milatovic, Dejan
AU - Aschner, Michael
AU - Feustel, Paul J.
AU - Kimelberg, Harold K.
N1 - Funding Information:
This work was supported by NIH NS35205 (H.K.K). The authors gratefully acknowledge Dr. Gary Schools for his instruction and advice on brain tissue collection and Yiqiang Jin and Layli Nazirova for their technical assistance.
PY - 2007/4
Y1 - 2007/4
N2 - We have previously shown that tamoxifen can induce marked neuroprotection after middle cerebral artery occlusion (MCAo) in rats and have described two possible mechanisms of action: namely, inhibition of EAA release and inhibition of nNOS activity. In this study we tested other potential mechanisms. Namely, agonist action at estrogen receptors and an antioxidative action. Tamoxifen-treated rats had significantly improved neurobehavioral deficit scores after 24 h and showed ∼ 75% reduced infarct volumes. These were unaffected by ICI 182,780 (a high affinity and pure receptor antagonist) administered intravenously, or intracisternally to avoid possible lack of brain penetration, 15 min before intravenous administration of tamoxifen. In rats subjected to 2 h MCAo followed by 22 h reperfusion, 1.8-fold and 2.9-fold increases of F2-IsoPs and F4 neuroprostanes, respectively, as relatively stable markers of oxidative damage, were measured in the ischemic hemisphere compared with the corresponding contralateral hemisphere or sham controls. Tamoxifen given at 3 h after the start of ischemia reduced the IsoPs and NeuroPs to sham control levels, and also inhibited their production by chemically induced lipid peroxidation in brain homogenates. These data are consistent with at least part of tamoxifen's marked neuroprotection in focal cerebral ischemic injury being due to its antioxidant activity but not by an acute action on estrogen receptors (212 words).
AB - We have previously shown that tamoxifen can induce marked neuroprotection after middle cerebral artery occlusion (MCAo) in rats and have described two possible mechanisms of action: namely, inhibition of EAA release and inhibition of nNOS activity. In this study we tested other potential mechanisms. Namely, agonist action at estrogen receptors and an antioxidative action. Tamoxifen-treated rats had significantly improved neurobehavioral deficit scores after 24 h and showed ∼ 75% reduced infarct volumes. These were unaffected by ICI 182,780 (a high affinity and pure receptor antagonist) administered intravenously, or intracisternally to avoid possible lack of brain penetration, 15 min before intravenous administration of tamoxifen. In rats subjected to 2 h MCAo followed by 22 h reperfusion, 1.8-fold and 2.9-fold increases of F2-IsoPs and F4 neuroprostanes, respectively, as relatively stable markers of oxidative damage, were measured in the ischemic hemisphere compared with the corresponding contralateral hemisphere or sham controls. Tamoxifen given at 3 h after the start of ischemia reduced the IsoPs and NeuroPs to sham control levels, and also inhibited their production by chemically induced lipid peroxidation in brain homogenates. These data are consistent with at least part of tamoxifen's marked neuroprotection in focal cerebral ischemic injury being due to its antioxidant activity but not by an acute action on estrogen receptors (212 words).
KW - Behavior
KW - ICI 182,780
KW - Infarct volume
KW - Isoprostanes
KW - Male Sprague-Dawley rats
KW - Middle cerebral artery occlusion
KW - Neuroprostanes
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U2 - 10.1016/j.expneurol.2007.01.015
DO - 10.1016/j.expneurol.2007.01.015
M3 - Article
C2 - 17321521
AN - SCOPUS:33947676341
SN - 0014-4886
VL - 204
SP - 819
EP - 827
JO - Experimental Neurology
JF - Experimental Neurology
IS - 2
ER -