Calcium ionophore-induced egg activation and apoptosis are associated with the generation of intracellular hydrogen peroxide.
The present study was designed to investigate whether calcium ionophore-induced activation and apoptosis are associated with the generation of hydrogen peroxide (H(2)O(2)) in rat eggs cultured in vitro. Culture of metaphase-II (M-II) arrested eggs in Ca(2+)/Mg(2+)-deficient medium did not induce egg activation, while a second polar body was observed in 20% of eggs when cultured in Ca(2+)/Mg(2+)-supplemented medium. In Ca(2+)/Mg(2+)-deficient medium, lower concentrations of calcium ionophore (0.2,0.4 and 0.8 microm) not only induced egg activation in a dose-dependent manner but also generation of intracellular H(2)O(2) (84.40+/-0.50 ng/egg) when compared to control eggs (80.46+/-1.34 ng/egg). The higher concentration of calcium ionophore (1.6 microm) induced apoptosis and pronounced generation of intracellular H(2)O(2) (92.43+/-0.93 ng/egg) in treated eggs. Conversely, cell-permeant antioxidant such as 2(3)-tert-butyl-4-hydroxyanisole (BHA) reduced intracellular H(2)O(2) level (81.20+/-1.42 ng/egg) and protected against calcium ionophore-induced morphological changes characteristics of egg activation and apoptosis. These results clearly suggest that calcium ionophore-induced activation and apoptosis are associated with the generation of intracellular H(2)O(2) in rat eggs.
Chaube
S K
SK
Cell Physiology, Centre of Advanced Study, Department of Zoology, Banaras Hindu University, Varanasi, India. shailchaubey@gmail.com
Khatun
Sabana
S
Misra
S K
SK
Shrivastav
T G
TG
D000818:Animals; D000975:Antioxidants / Q000737:chemistry; D017209:Apoptosis; D002083:Butylated Hydroxyanisole / Q000737:chemistry; D002118:Calcium / Q000737:chemistry*; D016895:Culture Media, Serum-Free; D053938:DNA Fragmentation; D005260:Female; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000494:pharmacology*; D020287:In Situ Nick-End Labeling; D007476:Ionophores / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry; D008677:Metaphase; D010539:Permeability; D051381:Rats
D000975:Antioxidants; D016895:Culture Media, Serum-Free; D007476:Ionophores; D002083:Butylated Hydroxyanisole; C051361:2-tert-butyl-4-hydroxyanisole; D006861:Hydrogen Peroxide; D008274:Magnesium; D002118:Calcium