title: The effects of estradiol and catecholestrogens on uterine glycogen metabolism in mink (Neovison vison).
abstract: Glycogen is a uterine histotroph nutrient synthesized by endometrial glands in response to estradiol. The effects of estradiol may be mediated, in part, through the catecholestrogens, 2-hydroxycatecholestradiol (2-OHE2) and 4-hydroxycatecholestradiol (4-OHE2), produced by hydroxylation of estradiol within the endometrium. Using ovariectomized mink, our objectives were to determine the effects of estradiol, 4-OHE2, and 2-OHE2 on uterine: 1) glycogen concentrations and tissue localization; 2) gene expression levels for glycogen synthase, glycogen phosphorylase, and glycogen synthase kinase-3B; and 3) protein expression levels for glycogen synthase kinase-3B (total) and phospho-glycogen synthase kinase-3B (inactive). Whole uterine glycogen concentrations (mean ± SEM, mg/g dry wt) were increased by estradiol (43.79 ± 5.35), 4-OHE2 (48.64 ± 4.02), and 2-OHE2 (41.36 ± 3.23) compared to controls (4.58 ± 1.16; P ≤ 0.05). Percent glycogen content of the glandular epithelia was three-fold greater than the luminal epithelia in response to estradiol and 4-OHE2 (P ≤ 0.05). Expression of glycogen synthase mRNA, the rate limiting enzyme in glycogen synthesis, was increased by 4-OHE2 and 2-OHE2 (P ≤ 0.05), but interestingly, was unaffected by estradiol. Expression of glycogen phosphorylase and glycogen synthase kinase-3B mRNAs were reduced by estradiol, 2-OHE2, and 4-OHE2 (P ≤ 0.05). Uterine phospho-glycogen synthase kinase-3B protein was barely detectable in control mink, whereas all three steroids increased phosphorylation and inactivation of the enzyme (P ≤ 0.05). We concluded that the effects of estradiol on uterine glycogen metabolism were mediated in part through catecholestrogens; perhaps the combined actions of these hormones are required for optimal uterine glycogen synthesis in mink.
authors.affiliation: Department of Biological Sciences, Idaho State University, Pocatello, Idaho 83209, USA. rosewill@isu.edu
authors.forename: Jack
authors.initials: J
authors.lastname: Rose
authors.forename: Jason
authors.initials: J
authors.lastname: Hunt
authors.forename: Jadd
authors.initials: J
authors.lastname: Shelton
authors.forename: Steven
authors.initials: S
authors.lastname: Wyler
authors.forename: Daniel
authors.initials: D
authors.lastname: Mecham
mesh_terms: D000818:Animals; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology*; D002393:Estrogens, Catechol / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006003:Glycogen / Q000032:analysis / Q000378:metabolism*; D024981:Glycogen Phosphorylase / Q000235:genetics; D006006:Glycogen Synthase / Q000235:genetics; D038362:Glycogen Synthase Kinase 3 / Q000032:analysis / Q000235:genetics; D000071679:Glycogen Synthase Kinase 3 beta; D008907:Mink / Q000378:metabolism*; D010052:Ovariectomy; D012333:RNA, Messenger / Q000032:analysis; D014599:Uterus / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D002393:Estrogens, Catechol; D012333:RNA, Messenger; D004958:Estradiol; D006003:Glycogen; C001390:2-hydroxyestradiol; C014036:4-hydroxyestradiol; D024981:Glycogen Phosphorylase; D006006:Glycogen Synthase; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3