Foeniculum vulgare (Fennel) Effects on Puberty Timing, Reproductive Function and Behaviour in Adult Female Mice Following Neonatal Exposure

Fennel, as an edible plant, and due to its estrogenic compounds, has widely been used as a therapeutic agent for centuries. In this study, the effects of neonatal exposure to fennel alcoholic extract (FAE), on the onset of puberty, estrus cycle, ovaries, and lordosis were investigated.

In this experimental study, 48 female BALB/c pups were divided into 4 groups: control (without treatment), treatment with estradiol benzoate (EB), 100 and 200 (mg/kg bw) FAE that were daily administered for 5 days from birth.

The age at vaginal opening (VO) was significantly earlier in EB and 200 FAE. Body weight at VO was lower than control only in EB. A disrupted estrus cycle, decreased number of cycles and increased index diestrus were observed in EB and 200 FAE treated mice. Ovary weight in the EB-, 100- and 200 FAE-treated groups were lower. The number of Graafian follicles in the EB-, 100- and 200 FAE and number of corpus luteum in the EB and 200 FAE groups were lower than that of control females. Estradiol concentration increased in the EB and 200 FAE and LH concentration decreased in the EB-, 100- and 200 FAE groups. The lordosis quotient (LQ) was significantly low in the EB- and 200 FAE-treated groups, vis-à-vis the control group.

The present results indicated that neonatal exposure to FAE induces early VO and disrupts ovary function. In addition, fennel acts like xenoestrogens and causes defeminization of the brain in the estrus cycle as well as lordosis in mice.