Dieldrin modifies the hydrolysis of PIP2 and decreases the fertilization rate in Bufo arenarum oocytes.
Carbachol treatment in Bufo arenarum oocytes decreases the radioactivity in [32P]PIP2 in the following 20 min after stimulation and increases the [3H]glycerol labeling of 1,2-DAG at 1 min of stimulation. On the contrary, in Dieldrin treated oocytes carbachol stimulation produces an increase in [32P]PIP2 labeling without changes in [3H]1,2-DAG radioactivity. The sustained hydrolysis of PIP2 observed in Control oocytes is necessary to generate the intracellular second messengers which initiate the fertilization pathway. The lack of response to muscarinic stimulation in Dieldrin treated oocytes, may be associated with an early activation of PIP2-PLC by the insecticide, producing a depletion of the PIP2 pool previous to the stimulation with carbachol. These changes take place simultaneously with a decrease in the ability of Bufo arenarum oocytes to be fertilized in vitro, suggesting a correlation between impairment in the PIP2 cascade and a decrease in the fertilization rate.
Fonovich de Schroeder
T M
TM
Libiquima, Facultad de Ingeniería, Universidad Nacional del Comahue, Buenos Aires, Neuquén, Argentina.
Pechén de D'Angelo
A M
AM
D019870:1-Phosphatidylinositol 4-Kinase; D000818:Animals; D002022:Bufo arenarum; D002217:Carbachol / Q000494:pharmacology; D004026:Dieldrin / Q000008:administration & dosage / Q000633:toxicity*; D004075:Diglycerides / Q000378:metabolism; D005260:Female; D005306:Fertilization / Q000187:drug effects*; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000378:metabolism*; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology / Q000187:drug effects*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism
C011439:1,2-diacylglycerol; D004075:Diglycerides; D007295:Inositol Phosphates; D018721:Muscarinic Agonists; D002217:Carbachol; C066454:inositol 4,5-bisphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); D019870:1-Phosphatidylinositol 4-Kinase; D004026:Dieldrin