title: Estradiol stimulates glycogen synthesis whereas progesterone promotes glycogen catabolism in the uterus of the American mink (Neovison vison).
abstract: Glycogen synthesis by mink uterine glandular and luminal epithelia (GE and LE) is stimulated by estradiol (E2) during estrus. Subsequently, the glycogen deposits are mobilized to near completion to meet the energy requirements of pre-embryonic development and implantation by as yet undetermined mechanisms. We hypothesized that progesterone (P4) was responsible for catabolism of uterine glycogen reserves as one of its actions to ensure reproductive success. Mink were treated with E2, P4or vehicle (controls) for 3 days and uteri collected 24 h (E2, P4and vehicle) and 96 h (E2) later. To evaluate E2priming, mink were treated with E2for 3 days, then P4for an additional 3 days (E2→P4) and uteri collected 24 h later. Percent glycogen content of uterine epithelia was greater at E2+ 96 h (GE = 5.71 ± 0.55; LE = 11.54 ± 2.32) than E2+24 h (GE = 3.63 ± 0.71; LE = 2.82 ± 1.03), and both were higher than controls (GE = 0.27 ± 0.15; LE = 0.54 ± 0.30; P < 0.05). Treatment as E2→P4reduced glycogen content (GE = 0.61 ± 0.16; LE = 0.51 ± 0.13), to levels not different from controls, while concomitantly increasing catabolic enzyme (glycogen phosphorylase m and glucose-6-phosphatase) gene expression and amount of phospho-glycogen synthase protein (inactive) in uterine homogenates. Interestingly, E2→P4increased glycogen synthase 1 messenger RNA (mRNA) and hexokinase 1mRNA and protein. Our findings suggest to us that while E2promotes glycogen accumulation by the mink uterus during estrus and pregnancy, it is P4that induces uterine glycogen catabolism, releasing the glucose that is essential to support pre-embryonic survival and implantation.
authors.affiliation: Department of Biological Sciences, Idaho State University, Pocatello, ID, USA.
authors.forename: Kole
authors.initials: K
authors.lastname: Bowman
authors.affiliation: Department of Biological Sciences, Idaho State University, Pocatello, ID, USA.
authors.forename: Jack
authors.initials: J
authors.lastname: Rose
mesh_terms: D000818:Animals; D047108:Embryonic Development; D004734:Energy Metabolism; D004958:Estradiol / Q000494:pharmacology* / Q000502:physiology*; D004971:Estrus / Q000378:metabolism*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D005947:Glucose / Q000378:metabolism; D005952:Glucose-6-Phosphatase / Q000235:genetics / Q000378:metabolism; D006003:Glycogen / Q000096:biosynthesis* / Q000378:metabolism*; D024981:Glycogen Phosphorylase / Q000235:genetics / Q000378:metabolism; D006006:Glycogen Synthase / Q000235:genetics / Q000378:metabolism; D008907:Mink / Q000378:metabolism*; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology* / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D013268:Stimulation, Chemical; D014599:Uterus / Q000378:metabolism* / Q000502:physiology
chemical_list: D012333:RNA, Messenger; D011374:Progesterone; D004958:Estradiol; D006003:Glycogen; D024981:Glycogen Phosphorylase; D006006:Glycogen Synthase; D005952:Glucose-6-Phosphatase; D005947:Glucose
keywords: estradiol; glycogen; mink; progesterone; uterus