Estrogen and bisphenol A disrupt spontaneous [Ca(2+)](i) oscillations in mouse oocytes.
The present work aims to study the effects of estrogen or endocrine disrupters (EDs) on the dynamic changes in intracellular Ca(2+) concentration of mouse immature oocytes (IOs) loaded with Ca(2+)-sensitive dye Fura-2 using an image analyzer. The majority of IOs isolated from the ovary exhibited spontaneous Ca(2+) oscillations at regular intervals. Entry of external Ca(2+), probably through gap junctions, contributes to Ca(2+) oscillations since they were reversibly inhibited by removing Ca(2+) from the bathing medium or by the application of a gap-junction inhibitor carbenoxolone (CBX, 30 microM). Both 17beta-estradiol (E2) and E2-BSA, a membrane impermeable estrogen, shortened the duration of Ca(2+) oscillations in a dose-dependent manner (1-1000 nM), and produced an irregular pattern of the oscillations, strongly suggesting that E2 acts on the plasma membrane of the oocyte. For bisphenol A (BPA), one of the estrogen-mimicking EDs, a 10,000-fold higher concentration (100 microM) was necessary to exert similar inhibitory action to that of E2.
Mohri
Tatsuma
T
Division of Intracellular Metabolism, Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan. tsmohri@nips.ac.jp
Yoshida
Shigeru
S
D000818:Animals; D001559:Benzhydryl Compounds; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008813:Mice, Inbred ICR; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology*; D010636:Phenols / Q000493:pharmacokinetics*; D000098826:Bisphenol A Compounds
D001559:Benzhydryl Compounds; D004967:Estrogens; D010636:Phenols; C006780:bisphenol A; D000098826:Bisphenol A Compounds