Pioglitazone suppresses excessive follicular development in murine preantral follicles

Abstract

Polycystic ovary syndrome (PCOS) is an endocrine disease that is common in women in their reproductive period. Patients with this disease suffer from anovulation and hyperandrogenism. Ovulation induction with exogenous gonadotropin often causes ovarian hyperstimulation syndrome because many small antral follicles pause in their growth. Treatment with insulin sensitizers is reportedly effective for both anovulation associated with PCOS, and suppression of excessive follicular growth; however, the underlying mechanism of action remains unknown. Although pioglitazone is known as an insulin sensitizer, it also has a potent modulator of cell growth and apoptosis irrespective of insulin resistance. To clarify the effect of pioglitazone on follicular growth, we performed in vitro culture of murine preantral follicles. Secondary follicles (100-160 μm in diameter) isolated from 6-week-old ICR mice were individually cultured for 13 days. Culture conditions were as follows: 1) follicle-stimulating hormone (FSH; 33 mIU/mL; control), 2) FSH plus dihydrotestosterone (DHT; 500 ng/mL), 3) FSH plus pioglitazone (5 ng/mL), and 4) FSH plus DHT/pioglitazone. Survival rate and follicle diameter were evaluated, and concentrations of estradiol (E2) and vascular endothelial growth factor (VEGF) in culture media were measured. mRNA expression of various growth-promoting factors and Vegf within follicles were also assessed. Although no significant differences were observed with regard to survival rate, follicle diameters on day 13 were significantly different. Compared with the control group, the DHT group showed enhanced growth, while groups administered pioglitazone showed stagnation of the accelerated growth induced by DHT. Although DHT treatment enhanced the expression of bone morphogenetic protein 2 ( Bmp2 ) mRNA, pioglitazone exposure suppressed induction of Bmp2 mRNA by DHT. Vegf mRNA and protein expression were also significantly reduced when pioglitazone was added to culture media containing DHT. Administration of pioglitazone negatively affected follicular growth and VEGF levels, which may suppress excessive follicular growth and prevent ovarian hyperstimulation syndrome.

The optimized research of the in vitro culture of preantral follicles in mice

“…Currently, the most commonly used method for in vitro culture of mouse preantral follicle is the two-dimensional droplet method. [1][2][3] The 80-180 μm preantral follicle is selected for in vitro culture, 13,22,23 and the commonly used r-FSH concentration is 10 mIU/ mL or 100 mIU/mL. 13,23,24 Under the same conditions, the average in vitro maturation rate of follicular oocytes is 60%-70%.…”

“…al also showed that FSH could promote the survival of preantral follicles with a diameter of 95-142 μm in mice. 21 Recently, preantral follicles with a diameter of 80-180 μm are often selected and used for in vitro culture, 13,22,23 and follicles in this diameter range include grade II, III, IV, and V follicles. The different grades of follicles have different amounts of granulosa cells and different sizes.…”

Current Advances in Cellular Approaches for Pathophysiology and Treatment of Polycystic Ovary Syndrome

“…Many studies have suggested that both endogenous and exogenous sources of androgen excess may directly contribute to the development of polycystic ovary morphology [91]. Table 3 has summarized the various rodent primary follicle cultures that have been used to investigate the stimulation of follicle growth by androgens [84,90,[92][93][94]. Among the strains of rodents provided by major suppliers, C57BL/6 and ICR mice are commonly used in studies related to aging, toxicology, pathology, and physiology [95].…”

Different expression and localization of aquaporin 7 and aquaporin 9 in granulosa cells, oocytes, and embryos of patients with polycystic ovary syndrome and the negatively correlated relationship with insulin regulation

“…It has been proven that increased insulin levels or IR can cause hypothalamic-pituitary-ovarian axis dysfunction, thereby inhibiting the synthesis and expression of sex hormone-binding globulin and indirectly causing increased levels of androgens in the body (6). In turn, high androgen concentrations cause IR, inhibiting follicular development and maturity, thereby affecting the quality of oocytes (7). In the granulosa cells of atretic follicles in patients with PCOS, IR-related insulin-like growth factors are abundantly expressed (8).…”