title: Estradiol reduces cytochrome c translocation and minimizes hippocampal damage caused by transient global ischemia in rat.
abstract: It is well-established that 17beta-estradiol (17beta-E(2)) confers neuroprotection to male and female rats exposed to focal cerebral ischemia, while less is known about the effects of the hormone under conditions of transient global ischemia. Since translocation of cytochrome c from the mitochondria to the cytosol is a critical step in apoptotic cell death after cerebral ischemia, we have investigated whether 17beta-E(2) interferes with such mechanism to exert neuroprotection. Global ischemia, induced in male Wistar rats by 5-min 4 vessel occlusion (4VO), resulted in a significant increase of cytosolic cytochrome c (cyt-c) levels as detected by Western blotting at 6h after reperfusion. 17beta-E(2) (0.2mg/kg, i.p.) given 1h before ischemia minimized cytochrome c translocation and the latter effect was partially reversed by tamoxifen (0.25mg/kg, i.p.). Bilateral cell counting revealed that delayed hippocampal damage typically caused by 4VO was abolished by 17beta-E(2) and this was partially reversed by tamoxifen in the CA3 subregion, but not in CA1/CA2 or CA4. These findings provide the original observation that 17beta-E(2) reduces delayed hippocampal damage caused by 4VO in male rats and blocks cytochrome c translocation during the early stages of neuronal death, thus providing an important mechanism involved in estrogen-mediated neuroprotection.
authors.affiliation: Department of Pharmacobiology, University of Calabria,Via Pietro Bucci, 87036 Arcavacata di Rende (CS), Italy. gbagett@tin.it
authors.forename: Giacinto
authors.initials: G
authors.lastname: Bagetta
authors.forename: Olga
authors.initials: O
authors.lastname: Chiappetta
authors.forename: Diana
authors.initials: D
authors.lastname: Amantea
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Iannone
authors.forename: Domenicantonio
authors.initials: D
authors.lastname: Rotiroti
authors.forename: Alfredo
authors.initials: A
authors.lastname: Costa
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Nappi
authors.forename: Maria Tiziana
authors.initials: MT
authors.lastname: Corasaniti
mesh_terms: D000818:Animals; D015153:Blotting, Western; D045304:Cytochromes c / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000473:pathology*; D002546:Ischemic Attack, Transient / Q000473:pathology*; D008297:Male; D018696:Neuroprotective Agents; D051381:Rats; D017208:Rats, Wistar; D013629:Tamoxifen / Q000494:pharmacology; D014178:Translocation, Genetic / Q000235:genetics
chemical_list: D004965:Estrogen Antagonists; D018696:Neuroprotective Agents; D013629:Tamoxifen; D004958:Estradiol; D045304:Cytochromes c