Protective effects of licorice extract on ovarian morphology, oocyte maturation, and embryo development in PCOS-induced mice: An experimental study

Abstract

Background: Polycystic ovary syndrome (PCOS) is an oxidative state resulting in ovarian dysfunction. Licorice is one of the natural antioxidants used for the treatment of infertility.

Objective: To evaluate the effect of licorice extract on ovarian morphology, oocyte maturation, and embryo development in PCOS-induced mice.

Materials and methods: thirty-two female NMIR mice were divided into four groups (n = 8/each): control group receiving no treatment (group I); PCOS group injected with estradiol valerate once daily for 21 days (group II); and experimental groups receiving either 100 mg/kg (group III) or 150 mg/kg (group IV) licorice by gavage along with estradiol valerate once daily for 3 wk. Serum levels of the testosterone and estrogen were measured using ELISA kit. Histological study of ovaries was evaluated, and oocyte maturation, fertilization rate, and embryo development were determined after in vitro maturation.

Results: Experimental groups (III, IV) had significantly higher testosterone and estradiol levels compared to the PCOS group (p $\le$ 0.001). A significant increase in the number of healthy follicles (primary, preantral follicles) (p = 0.001), corpus luteum (p = 0.001) with significant decrease in the number of atretic follicles (primary, preantral, cystic follicles) (p $\le$ 0.001) was seen in the experimental groups. Increase in the fertilization rate (p $\le$ 0.001) and blastocyst stage embryos (p = 0.02, p = 0.004) were observed in the experimental groups.

Conclusion: It appears that the two doses (100 mg and 150 mg) of licorice could decrease ovarian cyst and improve the fertilization rate of oocyte and embryo development in PCOS mice. However, there was no statistically significant difference between the two experimental groups.

Keywords: Histology; In vitro fertilization.; In vitro maturation; Licorice; Mice; Polycystic ovary syndrome.

Figure 1

Flow chart of the experimental design.

Figure 2

Histological changes in the ovarian tissue. Control (a): Section of ovary from a control group showing primordial follicles (PRIF), primary follicles (PF), preantral follicles (PAF), and antral follicles (AF). PCOS (b): Section of ovary from a PCOS group showing cystic follicle and atretic follicle. (c): Section of ovary from the experimental group (pro100) showing increased corpus luteum. (d): Section of ovary from the experimental group (pro150) showing increased corpus luteum.