title: Adrenomedullin: a possible regulator of germinal vesicle breakdown.
abstract: Adrenomedullin (ADM) is a multifunctional hormone that regulates processes as diverse as blood pressure and cell growth. Although expressed in the ovary, the role of ADM in this organ is not clear. In the present study, we found the expression of ADM receptor and receptor activity-modifying proteins in mouse cumulus cells but not in the oocytes. We report that germinal vesicle breakdown (GVBD), which is required for oocyte maturation, is not inhibited by ADM alone. However, ADM in the presence of the nitric oxide donor sodium nitroprusside (SNP) significantly inhibited GVBD. Furthermore, the ADM- and SNP-dependent inhibition of GVBD was abrogated by Akt blockade. Additionally, Akt expression and phosphorylation was exhibited by ADM, suggesting that Akt signaling upstream in cumulus cells is responsible. Additionally, immunohistochemical analysis revealed that ADM was localized in the granulosa cells of developed follicles, implying the possibility that ADM physiologically affects oocyte maturation in vivo. Our results provide the evidence that ADM can act as a GVBD regulator.
authors.affiliation: Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi Aobaku, Sendai 981-8555, Japan. hiradate@bios.tohoku.ac.jp
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Hiradate
authors.forename: Jun
authors.initials: J
authors.lastname: Ohtake
authors.forename: Yumi
authors.initials: Y
authors.lastname: Hoshino
authors.forename: Kentaro
authors.initials: K
authors.lastname: Tanemura
authors.forename: Eimei
authors.initials: E
authors.lastname: Sato
mesh_terms: D053607:Adrenomedullin / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D054885:Cumulus Cells / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D051379:Mice; D008813:Mice, Inbred ICR; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D058265:Receptors, Adrenomedullin / Q000235:genetics / Q000378:metabolism*
chemical_list: D020030:Nitric Oxide Donors; D012333:RNA, Messenger; D058265:Receptors, Adrenomedullin; D053607:Adrenomedullin; D009599:Nitroprusside; D051057:Proto-Oncogene Proteins c-akt