title: Chemical activation in Rhinella arenarum oocytes: effect of dehydroleucodine (DhL) and its hydrogenated derivative (2H-DhL).
abstract: Mature oocytes are arrested in metaphase II due to the presence of high levels of active maturation promoting factor (MPF). After fertilization, active MPF levels decline abruptly, enabling oocytes to complete meiosis II. One of the first and universal events of oocyte activation is an increase in cytosolic Ca2+ that would be responsible for MPF inactivation. Mature oocytes can also be activated by parthenogenetic activation. The aims of this work are to test the ability of dehydroleucodine (DhL) and its hydrogenated derivative 11,13-dihydro-dehydroleucodine (2H-DhL) to induce chemical activation in amphibian oocytes and to study the participation of calcium in the process. Results indicated that DhL and 2H-DhL induced oocyte activation in a dose-dependent manner. After 90 min of treatment, DhL 36 μM was able to induce 95% activation, while 2H-DhL 36 μM was less active, with only 40% activation. Our results suggest that DhL induced the inhibition of MPF activity, probably by an increase in intracellular Ca2+ concentration. Extracellular Ca2+ would not be significant, although Ca2+ release from intracellular stores is critical. In this sense, IP3Rs and RyRs were involved in the Ca2+ transient induced by lactones. In this species, RyRs appears to be the largest contributor to Ca2+ release in DhL-induced activation. Although more studies are needed on the mechanism of action through which these lactones induce oocyte activation in Rhinella arenarum, the results of this research provide interesting perspectives for the use of these lactones as chemical activators in in vitro fertilization and cloning.
authors.affiliation: Departamento de Biología del Desarrollo (INSIBIO),Chacabuco 461,4000 San Miguel de Tucumán,Argentina.
authors.forename: M F
authors.initials: MF
authors.lastname: Medina
authors.affiliation: Departamento de Biología del Desarrollo (INSIBIO); and Instituto de Biología,Facultad de Bioquímica,Química y Farmacia,Universidad Nacional de Tucumán,San Miguel de Tucumán,Argentina.
authors.forename: M I
authors.initials: MI
authors.lastname: Bühler
authors.affiliation: Departamento de Biología del Desarrollo (INSIBIO); and Instituto de Biología,Facultad de Bioquímica,Química y Farmacia,Universidad Nacional de Tucumán,San Miguel de Tucumán,Argentina.
authors.forename: G
authors.initials: G
authors.lastname: Sánchez-Toranzo
mesh_terms: D000818:Animals; D002022:Bufo arenarum; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D059471:In Vitro Oocyte Maturation Techniques; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism; D007783:Lactones / Q000494:pharmacology*; D008297:Male; D016200:Maturation-Promoting Factor / Q000037:antagonists & inhibitors / Q000378:metabolism; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology*; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012717:Sesquiterpenes / Q000494:pharmacology*
chemical_list: C518543:11,13-dihydro-dehydroleucodine; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007783:Lactones; D019837:Ryanodine Receptor Calcium Release Channel; D012717:Sesquiterpenes; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; C079949:dehydroleucodine; D004533:Egtazic Acid; D016200:Maturation-Promoting Factor; D002118:Calcium
keywords: Calcium; Dehydroleucodine; Oocyte activation; Rhinella arenarum