Diminished ovarian reserve (DOR) can lead to poor fertility and shorten the reproductive lifespan of female. The Dingkun Pill (DKP), a traditional Chinese-patented medication has been an integral part of Chinese treatment for centuries for the management of gynecological diseases. Relevant clinical studies have shown that DKP is able to protect against DOR, however, its mechanism of action is not yet fully known.
This experiment seeks to explore the impact of tripterygium wilfordii polyglycosidium (TWP) on the PI3K/AKT/mTOR pathway in the context of the pathophysiology of DOR and the mechanism of action of DKP.
Eighty female Balb/c mice with regular estrous cycle were divided into Blank, Model, DKP and hormone replacement therapy (HRT) group by random. With the exception of the Blank group, mice from other groups were exposed to 40 mg/kg/d TWP suspension for 30 days to induce DOR. Following this, either DKP or hormones were orally administrated to determine their effects on disease progression. During the experiment, the changes of body weight and estrous cycle of mice were observed. Post treatment, serum samples for anti-mullerian hormone (AMH), estradiol (E), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were taken to quantify their respective levels using enzyme-linked immunosorbent assay (ELISA). Mice were then sacrificed in order to harvest their ovaries for hematoxylin and eosin (HE) staining. This process allowed for assessment of ovary morphology and follicular quantification. Apoptotic ovarian cells of ovary were assessed by the TUNEL technique, while Caspase-3 and Cytochrome C (Cyt C) expression of ovary were examined with immunohistochemistry (IHC). Western blotting was used to quantify the levels of Bax, Bcl-2, Caspase-3, Cyt C, mTOR, P-mTOR, AKT, P-AKT, P-PI3K and PI3K proteins, while the mRNA levels of Bax, Bcl-2, PI3K, AKT and mTOR in ovarian tissue were measured by RT-PCR.
Findings revealed that DKP was able to improve levels of serum hormones and promote recovery of a normal estrous cycle. DKP augmented the total amount of primordial follicles while reducing the total follicles that were atretic follicles. The apoptosis index of growing follicles and Bax, Cyt C and Caspase-3 expressions were also decreased while increasing the Bcl-2: Bax ratio. DKP suppressed levels of the phosphorylation and mRNA expressions of mTOR, AKT and PI3K.
DKP was demonstrated to increase ovarian reserve through inhibition of the PI3K/AKT/mTOR signaling pathway, leading to suppression of primordial follicle activity and reduction in apoptosis of early growing follicles. This highlights its potentially useful role in the treatment of DOR.
Copyright © 2020. Published by Elsevier B.V.