Participation of PLA2 and PLC in DhL-induced activation of Rhinella arenarum oocytes.
Rhinella arenarum oocytes can be artificially activated, a process known as parthenogenesis, by a sesquiterpenic lactone of the guaianolide group, dehydroleucodine (DhL). Transient increases in the concentration of cytosolic Ca2+ are essential to trigger egg activation events. In this sense, the 1-4-5 inositol triphosphate receptors (IP3R) seem to be involved in the Ca2+ transient release induced by DhL in this species. We analyzed the involvement of phosphoinositide metabolism, especially the participation of phospholipase A2 (PLA2) and phospholipase C (PLC) in DhL-induced activation. Different doses of quinacrine, aristolochic acid (ATA) (PLA2 inhibitors) or neomycin, an antibiotic that binds to PIP2, thus preventing its hydrolysis, were used in mature Rhinella arenarum oocytes. In order to assay the participation of PI-PLC and PC- PLC we used U73122, a competitive inhibitor of PI-PLC dependent events and D609, an inhibitor of PC-PLC. We found that PLA2 inhibits quinacrine more effectively than ATA. This difference could be explained by the fact that quinacrine is not a specific inhibitor for PLA2 while ATA is specific for this enzyme. With respect to the participation of PLC, a higher decrease in oocyte activation was detected when cells were exposed to neomycin. Inhibition of PC-PLC with D609 and IP-PLC with U73122 indicated that the last PLC has a significant participation in the effect of DhL-induced activation. Results would indicate that DhL induces activation of in vitro matured oocytes of Rhinella arenarum by activation of IP-PLC, which in turn may induce IP3 formation which produces Ca2+ release.
Departamento de Biología del Desarrollo (INSIBIO),Chacabuco 461,4000 - San Miguel de Tucumán,Argentina.
J
J
Zapata-Martínez
Departamento de Biología del Desarrollo (INSIBIO),Chacabuco 461,4000 - San Miguel de Tucumán,Argentina.
M F
MF
Medina
Departamento de Biología del Desarrollo (INSIBIO),Chacabuco 461,4000 - San Miguel de Tucumán,Argentina.
M C
MC
Gramajo-Bühler
Departamento de Biología del Desarrollo (INSIBIO),Chacabuco 461,4000 - San Miguel de Tucumán,Argentina.
G
G
Sánchez-Toranzo
D000818:Animals; D034341:Aristolochic Acids / Q000494:pharmacology; D001952:Bridged-Ring Compounds / Q000494:pharmacology; D002022:Bufo arenarum; D004963:Estrenes / Q000494:pharmacology; D005260:Female; D059471:In Vitro Oocyte Maturation Techniques; D007783:Lactones / Q000494:pharmacology*; D009355:Neomycin / Q000494:pharmacology; D009636:Norbornanes; D009865:Oocytes / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D054467:Phospholipases A2 / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D011796:Quinacrine / Q000494:pharmacology; D012717:Sesquiterpenes / Q000494:pharmacology*; D013859:Thiocarbamates; D013871:Thiones / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D034341:Aristolochic Acids; D001952:Bridged-Ring Compounds; D004963:Estrenes; D007783:Lactones; D009636:Norbornanes; D010726:Phosphodiesterase Inhibitors; D011500:Protein Synthesis Inhibitors; D011760:Pyrrolidinones; D012717:Sesquiterpenes; D013859:Thiocarbamates; D013871:Thiones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C079949:dehydroleucodine; C046498:tricyclodecane-9-yl-xanthogenate; C000228:aristolochic acid I; D054467:Phospholipases A2; D010738:Type C Phospholipases; D011796:Quinacrine; D009355:Neomycin
Amphibian; Dehydroleucodine; Meiosis; Oocyte activation; Sesquiterpene lactones