J Ovarian Res., 2020., Mar 20;13(1):32. doi: 10.1186/s13048-020-00633-8.

A combination of spearmint and flaxseed extract improved endocrine and histomorphology of ovary in experimental PCOS.


BACKGROUND:  Polycystic ovary syndrome (PCOS) is a complex reproduction and endocrine disorder of women in the reproductive age. Spearmint (Mentha spicata L.) has anti-androgenic activity and flaxseed (Linum usitatissimum L.) contains phytoestrogen and was reported to improve PCOS conditions. This study aimed to evaluate PCOS conditions following administration of a mixture of these two plants. METHODS:  Twenty-four rats with regular cycles were randomly divided into four groups as control (C) and treatment-control (TC) received a combination of spearmint extract (SE) + flaxseed extract (FE). PCOS was induced in PCOS and treatment (T) groups by a single intramuscular injection of estradiol valerate. The treatment group received a combination of SE and FE for 30 days, 7 weeks after injection of estradiol valerate. Estrous cycles were monitored for 10 days and in the last day animals were sacrificed, ovaries were collected for the histomorphometric study and the serum levels of progesterone, testosterone, estradiol, and dehydroepiandrosterone (DHEA) were measured. RESULT:  Significant rise in progesterone and a decrease in testosterone and estradiol with no significant change of DHEA in the T group, was observed in comparison with the PCOS group (P < 0.05). No significant difference noticed between T and control groups (C &CT) regarding evaluated hormones. A significant increase in primary, pre-antral and antral follicles noticed in the T group compared to the PCOS group. The number of cystic follicles decreased in the T group compared with the PCOS group. Granulosa layer thickness increased while the thickness of theca decreased significantly in the T group compared to the PCOS group (P < 0.05). No significant endocrine or histological differences noticed between C and TC groups. CONCLUSION:  A combination of flaxseed and spearmint extract improved the endocrine profile and the histomorphometric features of the ovary in the T group compared to the PCOS group.

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Key Points

A problem in PCOS is anovulation due to hormonal imbalance. Luteinizing hormone (LH) level is higher, but the follicle-stimulating hormone (FSH) level is lower in PCOS patients compared to normal women. Follicle accumulation, absence of corpus luteum and rise in the ovarian volume are some of the signs of ovaries with PCOS. Spearmint and flaxseed have been recommended and used for the treatment of PCOS.  Flaxseed is recommended for the treatment of endocrine disorder and regulation of female sex hormones. Administration of flaxseed hydroalcoholic extract to rat with PCOS have been reported to improve endocrine status. Flaxseed is a rich source of dietary lignan. The lignan’s content of flaxseed may alter the activity of key enzymes involved in estrogen synthesis (e.g., aromatase) to modulate relative levels of circulating sex hormones and their metabolites. Moreover, lignan can inhibit the 5 α-reductase (the enzyme which is responsible for converting testosterone into DHT) leading to improvement of androgen levels in PCOS patients. Considering the anti-androgenic trait of spearmint and phytoestrogen features of flaxseed and the fact of imbalance of steroid hormones in PCOS, this study was designed to assess the role and effect of administration of a combination of these two plants on endocrine profile and histological change of ovary in estradiol valerate-induced PCOS rats.

In the current study level of testosterone decreased in the PCOS rats treated with a combination of spearmint and flaxseed extracts, which may be due to the anti-androgenic effect of spearmint and phytoestrogen action of flaxseed.

The level of estradiol also decreased significantly in the treatment group received a combination of flaxseed and spearmint extract in comparison with the PCOS group. The decrease in the level of estradiol could be due to the presence of lignan in flaxseed that may lead to a rise in SHBG production which in turn decreases the level of free estradiol. In summery administration of a combination of spearmint and flaxseed extract to PCOS animals improved endocrine secretion including estradiol, progesterone and testosterone level and ovarian histology which are more remarkable than using flaxseed or spearmint alone, reported previously. The results highlighted the potential effects of using a combination of spearmint and flaxseed extract for treatment of PCOS.