Submitted January 25, 2007
Returned for revision February 15, 2007
Accepted May 30, 2007
Toxicology
Induction of Apoptosis by 9,10-Dimethyl-1,2-benzanthracene in Cultured Preovulatory Rat Follicles Is Preceded by a Rise in Reactive Oxygen Species and Is Prevented by Glutathione
Miyun Tsai-Turton ,
Brooke N. Nakamura ,
and
Ulrike Luderer *
* To whom correspondence should be addressed. E-mail: uluderer{at}uci.edu.
Abstract
The polycyclic aromatic hydrocarbon (PAH) 9,10-Dimethyl-1,2-benzanthracene (DMBA) destroys primordial, primary, and secondary ovarian follicles in rodents, but its effects on antral follicles have received limited attention. PAHs are metabolized to reactive species, some of which can undergo redox cycling to generate reactive oxygen species (ROS). We previously showed that ROS initiate apoptosis in preovulatory follicles cultured without gonadotropin support, and that glutathione (GSH) depletion induces apoptosis in the presence of gonadotropins. Herein we tested the hypothesis that DMBA induces apoptosis in preovulatory follicles, which is mediated by ROS and is prevented by GSH. Preovulatory follicles were isolated from ovaries of 25-day-old rats 48h after injection of 10 IU eCG and were cultured with DMBA in the presence of FSH for 2 to 48 h. DMBA induced granulosa cell (GC) and theca cell (TC) apoptosis at 48 h, as judged by TUNEL and activated caspase 3 immunostaining. DMBA treatment also increased the numbers of GCs and TCs that immunostained for the proapoptotic protein BAX. Follicular ROS levels were significantly increased in DMBA-treated follicles at 12, 24 and 48 h. GSH supplementation protected against and GSH depletion enhanced the induction of apoptosis in GCs and TCs by DMBA. These findings suggest that GSH is a critical protective mechanism against DMBA-induced apoptosis in antral follicles and that ROS generation may mediate DMBA-induced GC apoptosis.
Key words:
Toxicology •
Apoptosis •
Follicle •
glutathione •
polycyclic aromatic hydrocarbon
