Short communication: Concentrations of the mammalian lignan enterolactone in preovulatory follicles and the correlation with intrafollicular estradiol in dairy cows fed extruded flaxseed

Association between Capillaria hepatica infection-induced alterations in gut microbiota and estrogen expression in Brandt's voles (Lasiopodomys brandtii)

BACKGROUND

Capillaria hepatica, a zoonotic parasite, is present in the population of Brandt's voles (Lasiopodomys brandtii) and has been a central issue in ecological studies regarding its impact on host populations. Brandt's voles are known for their extremely high reproductive capacity, and the population explosion of Brandt's voles have occurred multiple times in the grasslands of Inner Mongolia over the past few decades. However, the mechanisms underlying the population dynamics of Brandt's voles, particularly in response to C. hepatica infection, remain poorly understood. Given the critical role of the gut microbiota in modulating hormones within the reproductive endocrine system, this study aims to explore how alterations in the gut microbiota influence the host's population dynamics in response to C. hepatica infection.

METHODS

Female Brandt's voles were inoculated with eggs of infected C. hepatica, and BALB/C mice were used as a control. At the end of the experimental period, cecal contents were collected for 16 S rRNA amplicon sequencing, and the expression levels of reproductive-related hormones were determined using enzyme-linked immunosorbent assay (ELISA).

RESULTS

C. hepatica infection leads to an increased diversity of gut microbiota in Brandt's voles, with significant changes in microbial composition. The relative abundance of Muribaculaceae and Eubacteriaceae increased significantly, while that of Rikenellaceae and Lachnospiraceae decreased significantly. The expression level of estradiol in the serum of infected Brandt's voles shows a slight decrease without statistical significance. However, the expression of equol is significantly higher in the infected group compared to the uninfected group, and the expression of enterolactone is significantly lower in the infected group than in the uninfected group.

CONCLUSIONS

This study demonstrates that infection with C. hepatica indirectly affect the abundance of specific gut microbiota in Brandt's voles, which are associated with reproductive hormones. This indirect effect on hormone expression can subsequently impact the reproductive function of the host. By investigating the changes in specific gut microbiota, this study sheds light on the mechanisms through which parasites regulate population fluctuations in Brandt's voles.

The Role of Primary Cilia in Modulating the Luteinization Process of Ovarian Granulosa Cells in Mice

The corpus luteum is the principal progesterone-secreting gland, while primary cilia function as pivotal organelles in intercellular signal transduction. Together, they play an essential role in the establishment and maintenance of pregnancy. However, the mechanisms underlying the role of primary cilia in granulosa cell luteinization in mouse ovaries remain poorly understood. This study discovered the regularity of primary cilia in mouse ovaries and revealed the role of primary cilia in regulating progesterone synthesis in luteinized granulosa cells. In vivo test results showed that the expression of primary cilia was obvious in the corpus luteum. The secretion of P4 in mice was significantly increased at 6, 12, 24, 48, and 72 h. The secretion of P4 and the expressions of luteinization markers (STAR, 3β-HSD) and primary ciliate proteins (IFT88, Arl13B) were significantly up-regulated at different time points (6, 12, 24 h and 24, 48, 72 h), and the INS group was significantly higher than the LH group and the control. In vitro test results showed that the follicular granulosa cells were luteinized under INS, the length and number of primary cilia increased, and the secretion of progesterone increased. The expression levels of STAR and 3β-HSD of the primary cilia marker Arl13B and luteinization markers were increased, while the expression levels of CYP19A1 were decreased. Ciliobrevin A (CBA) and Y-27632 2HCl were used to regulate the expression of primary cilia. The results showed that after CBA treatment, the expression level of cilia protein Arl13B decreased, and the secretion level of P4 and the expression levels of STAR and 3β-HSD decreased, indicating that the level of luteinization decreased. Conversely, after inducing ciliogenesis with Y-27632 2HCl, the results were the opposite of those observed with CBA treatment. In conclusion, our study demonstrates that primary cilia regulate the expression of steroidogenic enzymes, thereby promoting progesterone secretion by granulosa cells in mice and ensuring proper luteinization.

The What and Who of Dietary Lignans in Human Health: Special Attention to Estrogen Effects and Safety Evaluation

Lignans are a group of phenolic compounds found in plant-based diets. The human body can obtain lignans through diet, which are then metabolized into enterolignans. The enterolignans have been linked to several health benefits, including anticancer, anti-inflammatory, antioxidant effects, and estrogen effects. This review explores the relationship between the estrogenic effects of lignans and health. This review not only considers the estrogen-like activity of lignans but also discusses the safe dosage of lignans at different life stages. In addition, this review also identified other types of bioactive compounds that can act synergistically with lignans to promote health. Studies have shown that lignan administration during pregnancy and lactation reduces the risk of breast cancer in offspring. Further studies are needed to investigate the estrogenic safety effects of lignan on pregnant women and children. Whether lignans combine with other nutrients in complex food substrates to produce synergistic effects remains to be investigated. This review provides a basis for future studies on the safe dose of lignan and recommended dietary intake of lignan. We believe that the acquired as discussed here has implications for developing dietary therapies that can promote host nutrition and modulate estrogenic diseases.

Influence of Flaxseed (Linum usitatissimum) on Female Reproduction

This review describes the chemical composition of flaxseed (Linum usitatissimum) and its general health effects, as well as the currently available knowledge concerning its action on the female reproductive state, functions on the ovary and ovarian cells and reproductive hormones, as well as possible constituents and extra- and intracellular mediators mediating its effects on female reproductive processes. Flaxseed contains a number of biologically active molecules, which, acting through multiple signalling pathways, can determine numerous physiological, protective and therapeutic effects of flaxseed. The available publications demonstrate the action of flaxseed and its constituents on the female reproductive system - ovarian growth, follicle development, the resulting puberty and reproductive cycles, ovarian cell proliferation and apoptosis, oo- and embryogenesis, hormonal regulators of reproductive processes and their dysfunctions. These effects can be determined by flaxseed lignans, alpha-linolenic acid and their products. Their actions can be mediated by changes in general metabolism, metabolic and reproductive hormones, their binding proteins, receptors and several intracellular signalling pathways, including protein kinases, transcription factors regulating cell proliferation, apoptosis, angiogenesis and malignant transformation. Flaxseed and its active molecules are found potentially useful for improving farm animal reproductive efficiency and treatment of polycystic ovarian syndrome and ovarian cancer.

In vitro exposure of sheep ovarian tissue to the xenoestrogens zearalenone and enterolactone: Effects on preantral follicles

The aim of this study was to evaluate the effect of 1 μmol/L zearalenone (ZEN) and 1 μmol/L enterolactone (ENL), alone or in combination, on the survival and morphology of in vitro cultured ovarian preantral follicles. Ovaries from 10 sheep were collected at a local abattoir and fragmented, and the ovarian pieces were submitted to in vitro culture for 3 days in the presence or absence of the test compounds. The morphology of primordial and primary follicles was impaired by ZEN, whereas that of cultured secondary follicles was improved by ENL. However, the combination of ENL with ZEN impaired the quality of primary and secondary follicles. Both ZEN and ENL induced apoptosis, but only ZEN was responsible for oocyte autophagy. None of these xenoestrogens affected endoplasmic reticulum stress as observed by the unaltered expression of ERP29. Differently from ZEN, ENL increased the expression of the efflux transporter ABCG2. In conclusion, although ENL can counteract the negative effects of ZEN on primordial and primary follicles, this positive effect is not similar to that observed in ovarian tissue cultures in the presence of ENL alone.