The effect of mTOR activation and PTEN inhibition on human primordial follicle activation in ovarian tissue culture.

Purpose: The effect of PTEN inhibitor (Bpv(HOpic); Bpv) and mTOR activators (phosphatidic acid (PA) and propranolol (PP)), were evaluated on the activation and subsequent development of human primordial follicles in ovarian tissue culture.

Methods: Slow frozen-thawed human ovarian cortical strips were incubated for 24 h in different groups: (1) Control (base medium), (2) Bpv (100 µM), (3) PA (200 µM), (4) PA + PP (50 µm), and (5) Bpv + PA + PP. Afterward, the medium was exchanged, and all groups were cultured without stimulators for 6 additional days. The proportion of normal and degenerated follicles, estradiol secretion, and expression of RPS6, FOXO3a, and AKT proteins was evaluated and compared between groups.

Results: After 24 h of culture, there was no significant difference between the proportion of primordial and growing follicles in either of the experimental groups. This non-significant change was also observed for the phosphorylated protein to total protein ratios of RPS6, FOXO3a, and AKT proteins. After 7 days of culture, the proportion of the transitional follicles was significantly higher in comparison to the primordial follicles for the PA, PA + PP, and Bpv + PA + PP groups. The estradiol level was significantly higher on the last day compared to the first day, in PA, PA + PP, and Bpv + PA + PP groups. Hormonal secretion was significantly higher in the PA and PA + PP groups and lower in the Bpv and Bpv + PA + PP groups compared to the control on day 7 of culture.

Conclusion: Temporary in vitro treatment of human ovarian tissue with mTOR activators enhances the initiation of primordial follicle development and positively influences steroidogenesis after short-term culture.