Aristolochic Acid I induces ovarian toxicity by inhibition of akt phosphorylation.

ABSTRACT

Aristolochic acids are natural products found in Chinese herbs of the Aristolochiaceae family. Aristolochic acid I (AAI) is a potent carcinogen and was found to be toxic in animal and clinical studies. Apoptosis is a rapid, selective process of physiological cell deletion that regulates the balance between cell proliferation and cell death and is induced by various kinds of damage. However, the toxicity of AAI during ovarian maturation in the mouse is unclear and is the subject of the present investigation. We used Chinese hamster ovary-K1 (CHO-K1) cells and an AAI injection mouse model MTT assay was used to assess AA toxicity to cells; ovary size and weight were measured to determine the toxicity of AA to mouse ovary; western blot was used to assess apoptosis; TUNEL assay was used to evaluate apoptotic cell death; and immunohistochemistry was used to examine the local expression of apoptotic proteins in ovary tissue. We found that AAI significantly inhibits the viability of CHO-K1 cells and strongly induces apoptotic cell death in CHO-K1 cells and in mouse ovary. In addition, we observed that AAI markedly increases the expression of pro-apoptotic proteins, including Bax, caspase-3, caspase-9, and poly(ADP) ribose polymerase (PARP). In contrast, anti-apoptotic proteins, such as Bcl-2 and survivin, were decreased by AAI treatment. Furthermore, we observed that ovary size and weight were significantly reduced and that the number of ovulated oocytes was markedly suppressed in AAI-treated mice. These results suggest that AAI strongly induces toxic damage during ovarian maturation by inhibiting Akt phosphorylation-mediated suppression of apoptosis.