Methoxychlor (MXC) is an organochlorine pesticide that was developed to replace dichlorodiphenyltrichloroethane (DDT). MXC is less persistent than DDT; nevertheless, it is considered a potent environmental toxicant. We have previously shown that MXC affects the ovary by increasing the rate of ovarian atresia and decreasing the number of healthy antral follicles. Atresia is thought to begin with apoptosis in the granulosa cells.
Although there are many factors that regulate apoptosis, the B cell lymphoma 2 (Bcl-2) family of proteins is considered to be a major regulator of this process. This family of proteins is part of what has been referred to as the decision step in apoptosis, during which a cell’s fate is determined. The Bcl-2 family consists of both antiapoptotic members (e.g., Bcl-2, Bcl-xl, Boo) and proapoptotic members (e.g., Bax, Bok, Bim, Bid). It is thought that the relative ratio between pro- and antiapoptotic proteins determines whether the cell will live or die, i.e., a greater ratio of pro- to antiapoptotic proteins would result in the drive toward apoptosis.