title: Multiple forms of estrogen receptor-alpha in cerebral blood vessels: regulation by estrogen.
abstract: The cerebral vasculature is an important target tissue for estrogen, as evidenced by significant effects of estrogen on vascular reactivity and protein levels of endothelial nitric oxide synthase and prostacyclin synthase. However, the presence, localization, and regulation of estrogen receptors in the cerebral vasculature have not been investigated. In this study, we identified the presence of estrogen receptor-alpha (ER-alpha) in female rat cerebral blood vessels and localized this receptor to both smooth muscle and endothelial cells by use of immunohistochemistry and confocal microscopy. With immunoblot analysis, multiple forms of ER-alpha were detected at 110, 93, 82, 50, and 45 kDa in addition to a relatively weak band corresponding to the 66-kDa putative unmodified receptor. The 82-kDa band was identified as Ser(118)-phosphorylated ER-alpha, whereas the 50-kDa band lacks the normal NH(2) terminus, suggestive of an ER-alpha splice variant. Lower molecular mass bands persisted after in vivo inhibition of 26S proteasome activity with lactacystin, whereas the 110- and 93-kDa bands increased. All forms of ER-alpha in cerebral vessels were decreased after ovariectomy but significantly increased after chronic estrogen exposure in vivo.
authors.affiliation: Department of Pharmacology, College of Medicine, University of California, Irvine 92697-4625, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Stirone
authors.forename: Sue P
authors.initials: SP
authors.lastname: Duckles
authors.forename: Diana N
authors.initials: DN
authors.lastname: Krause
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001808:Blood Vessels / Q000737:chemistry* / Q000187:drug effects; D015153:Blotting, Western; D001921:Brain / Q000098:blood supply*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000737:chemistry; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D005260:Female; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D009131:Muscle, Smooth, Vascular / Q000737:chemistry; D019001:Nitric Oxide Synthase / Q000032:analysis; D052250:Nitric Oxide Synthase Type III; D010052:Ovariectomy; D010447:Peptide Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D010841:Pia Mater / Q000098:blood supply; D046988:Proteasome Endopeptidase Complex; D051381:Rats; D011916:Rats, Inbred F344; D011960:Receptors, Estrogen / Q000032:analysis* / Q000378:metabolism
chemical_list: D015853:Cysteine Proteinase Inhibitors; D047628:Estrogen Receptor alpha; D011960:Receptors, Estrogen; C067713:lactacystin; D010768:Phosphoserine; D004958:Estradiol; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000111:Acetylcysteine