Effect of licorice extract on ovulation induction in immature female mice

I K Al-Muala,B.M Al-Jiboori

doi:10.24126/jobrc.2010.4.1.106

Abstract

The objective of this study was to assess the effect of licorice extract (LE) on induction of ovulation and on the structural changes of ovary, oviduct and uterus. Divided into 6 groups: G1, G2, G3, G4, G5 and G6 (14 animals for each). G1 received 1g/kg bwt/day of licorice extract for 2 weeks. G2 were fed with 0.5g/kg bwt/day of licorice extract for 2 weeks. Mice fed on normal diet and tap water (without LE) were regarded as control group (G3). G4 and G5 received the same doses of G1 and G2 respectively for 4 weeks. G6 received tap water only and considered as a control for G4 and G5. Before the initiation of dosing, vaginal smears were taken daily and ceased when estrus phase of first ovarian cycle appeared. At the end of the experiment, animals were sacrificed and reproductive system were excised and divided into two sides: the left one only was used for histological studies. The results indicated that LE consumption caused an increase in the diameter of the ovary, total number of follicles and their diameters of all mice treated with a higher dose and longer duration. Dose of 1g/kg bwt/day was also more effective upon measuring the diameters of uterine glands and the diameter of the oviductal ampulla, while the lower dose gave higher results only in measuring the height of endometrial epithelial lining cells and the oviductal epithelial lining cells. There was a significant precocious estrus cycle in animals that treated with 1g/kg bwt/day and a non significant precocity with 0.5g/kg bwt/day, as compared to the control group. These results may be attributed to the effect of various components of LE, especially estrogen-like substances in addition to other components like: proteins, amino acids, vitamins and trace elements present in the licorice. The results of the present study indicate that the use of low doses of LE (0.5, 1)g for a short period of time 2-4 weeks improved the reproductive organs, induced earlier estrus cycle and consequently may improve the reproduction. The consumption of 1g licorice extract daily for 4 weeks induced sexual maturity better than the other dose and period.

Highlights

R was regarded as control group (G3)
Follicular development depends on production of E2, which acts within the follicle in an autocrine and paracrine manner, E2 promotes proliferation of granulosa cells and increases their responsiveness to FSH, E2 may stimulate proliferation of theca interna cells, simultaneously, E2 and FSH induce granulosa cells to synthesize receptors for LH, granulosa cells of preovulatory follicles have abundant LH receptors and have acquired sensitivity to LH [21]
The positive results in the uteri concerning the increase in the height of endometrial epithelial lining cells and the diameter of endometrial glands reflect the importance of ingestion this herb at the peripubertal age, since it is well known that estrogens promote growth and development of the oviducts, uterus, vagina and external genitalia, estrogens stimulate cellular proliferation in the mucosal linings as well as in the muscular coats of these structures at puberty [21], so the positive results in uteri of the treated animals may be correlated with the presence of the estrogen-like substance in licorice because the uteri are extremely sensitive to exogenous estrogen [24]