The loss of estrogen efficacy against cerebral ischemia in aged postmenopausal female mice.
Estrogen has been shown to have neuroprotective effects in numerous experimental studies involving young and adult animals. However, several clinical trials have found that in aged postmenopausal women who received estrogen replacement therapy, there did not appear to be a reduction in the incidence of stroke. The aim of this study was to investigate the effects of physiological dosages of estrogen on aged female mice subjected to ischemia-reperfusion injury. Adult ovariectomized (OVX) female mice and 22-month-old female mice received daily subcutaneous injections of 100 μg/kg or 300 μg/kg 17β-estradiol (E2) at the back of the neck for four weeks, and the expression levels of estrogen receptor (ER) α and β in the cerebral cortex were determined using real-time PCR and Western blotting analyses. To mimic ischemic stroke, the mice received middle cerebral artery occlusion (MCAO) treatment for 1h followed by a 24-h reperfusion period. The mice were then subjected to neurological deficit testing and infarct volume evaluation. The aged mice showed higher neurological deficit scores and larger infarct volumes compared with the adult mice. Both the lower and higher physiological dosages of E2 significantly improved the neurological test scores and decreased the infarct volume in the adult mice; however, E2 showed no neuroprotective effects in the aged mice. Furthermore, the protein expression of ERα and ERβ in the cerebral cortex was significantly decreased in the aged mice compared with the adult mice, and this decrease was not rescued by E2 treatment. These results indicate that the down-regulation of ERα and ERβ in the cerebral cortex may contribute to the loss of estrogen efficacy against ischemic injury in aged females and may point to new therapies for ischemic stroke in aged postmenopausal women.
Department of Anesthesiology, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China; Department of Psychosomatic Medicine, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China.
Min
M
Cai
Department of Anesthesiology, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China.
Yu-Long
YL
Ma
Department of Anesthesiology, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China.
Pei
P
Qin
Department of Anesthesiology, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China.
Yan
Y
Li
Department of Ophthalmology, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China.
Li-Xia
LX
Zhang
Department of Anesthesiology, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China.
Huang
H
Nie
Department of Psychosomatic Medicine, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China.
Zhengwu
Z
Peng
Department of Anesthesiology, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China.
Hui
H
Dong
Department of Anesthesiology, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China.
Hai-Long
HL
Dong
Department of Anesthesiology, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China. Electronic address: gangwuhou@163.com.
Wu-Gang
WG
Hou
Department of Anesthesiology, Xijing hospital, The Fourth Military Medical University, Xi'an 710032, China. Electronic address: mzkxlz@126.com.
Li-Ze
LZ
Xiong
D000367:Age Factors; D000818:Animals; D002545:Brain Ischemia / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D002544:Cerebral Infarction / Q000188:drug therapy / Q000209:etiology / Q000473:pathology; D004958:Estradiol / Q000097:blood / Q000627:therapeutic use*; D047628:Estrogen Receptor alpha / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000378:metabolism; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000097:blood / Q000627:therapeutic use*; D005260:Female; D020244:Infarction, Middle Cerebral Artery / Q000150:complications; D008810:Mice, Inbred C57BL; D018696:Neuroprotective Agents / Q000097:blood / Q000627:therapeutic use*; D010052:Ovariectomy; D017698:Postmenopause
D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens; D018696:Neuroprotective Agents; D004958:Estradiol
17β-estradiol; 2,3,5-triphenyltetrazolium chloride; Aged; C terminus of heat shock cognate protein 70 (Hsc70)-interacting protein; CHIP; CNS; E2; ER; Estrogen; GCI; HRT; Ischemia; LTED; MCAO; Neuroprotection; OVX; Postmenopausal; TTC; central nervous system; estrogen receptor; global cerebral ischemia; hormone replacement therapy; long-term 17β-estradiol deprivation; ovariectomized; rCBF; regional cerebral blood flow; transient middle cerebral artery occlusion