The Role of Bax in Fetal Ovarian Germ Cell Apoptosis Induced by 4(3H) Quinazolinone-2-Ethyl-2-Phenyl Ethyl (QEPE)

Objective: Recently reports demonstrated quinazolinones, heterocyclic components with biological and pharmacological properties (anti cancer, anti microbial, anti malaria, anti allergic, anti spasm, etc...) as tumor suppressors via programmed cell death (apoptosis). Apoptosis is the main cause of primordial germ cell and oocyte degeneration in developing fetal ovary. Early morphological studies have shown that cell death affects proliferating primordial gem cells or oogonia (12-13 days post coitum, d.p.c.) and mainly oocytes at the zygotene/pachytene stages of mouse meiotic prophase (from 16.5 d.p.c. through birth). Bax, a proapoptotic member of the Bcl-2 family of cell death regulators, is one of the key genes that regulates apoptosis in fetal ovary. The purpose of this study was to examine the occurrence of apoptosis and investigate the expression of Bax in ovaries of normal and 4 (3H) quinazolinone-2-ethyl-2-phenyl ethyl (QEPE) treated Balb/C mice. Materials and Methods: Pregnant Balb-C mice were divided into three groups of control (intact), sham (receiving 0.05% methyl cellulose as solvent) and experimental group (receiving 100 mg of QEPE/Kg/body weight, the most effective dose,) intraperitoneally (IP). Ovaries were removed from normal and abnormal embryos of all pregnant mice on 16.5 d.p.c. and 18.5 d.p.c., 48 hours after injection. Hematoxylin and eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL)analysis were used to assess apoptosis. RT-PCR was performed to study the expression of Bax. Results: Some developing oocytes were detected identified as TUNEL positive by their dark stained nuclei in ovaries of embryos of control and sham groups. TUNEL positive cells were more abundant in ovaries of embryos of experimental group compared with control and sham groups. Bax mRNA was detected in the control and sham embryonic ovaries. RT-PCR analysis revealed that Bax expression increased in experimental embryonic ovaries. Conclusion: These results suggest that Bax expression and apoptosis in germ cells are common events occurring during development and QEPE as a developmental toxicant would increase Bax expression and apoptosis rate in mouse fetal ovary in agreement with previous studies about other toxicants. Apoptosis of damaged germ cells may serve a critical role in protecting subsequent generations from the diverse effects of toxicants.