Genistein, a phytoestrogen, effectively modulates luteinizing hormone and prolactin secretion in ovariectomized ewes during seasonal anestrus

Environmental disruption of reproductive rhythms

Reproduction is a key biological function requiring a precise synchronization with annual and daily cues to cope with environmental fluctuations. Therefore, humans and animals have developed well-conserved photoneuroendocrine pathways to integrate and process daily and seasonal light signals within the hypothalamic-pituitary-gonadal axis. However, in the past century, industrialization and the modern 24/7 human lifestyle have imposed detrimental changes in natural habitats and rhythms of life. Indeed, exposure to an excessive amount of artificial light at inappropriate timing because of shift work and nocturnal urban lighting, as well as the ubiquitous environmental contamination by endocrine-disrupting chemicals, threaten the integrity of the daily and seasonal timing of biological functions. Here, we review recent epidemiological, field and experimental studies to discuss how light and chemical pollution of the environment can disrupt reproductive rhythms by interfering with the photoneuroendocrine timing system.

Regulatory Effects of Soy Isoflavones and Their Metabolites in Milk Production via Different Ways in Mice

Soy products contain abundant genistein and daidzein isoflavones. Orally ingested soy isoflavones are partially metabolized to isoflavan by enteric bacteria. Their levels in the blood increase after soy products are eaten. In this study, we investigated the influence of genistein, daidzein, and equol by intraperitoneal administration in lactating mice. Genistein decreased the secretion of α- and β-casein and downregulated the gene expression of Csn1, Csn2, Csn3, and Wap while inactivating the signal transducer and activator of transcription 5 (STAT5) and ERK1/2. In contrast, equol increased Csn1-3 expression while inactivating STAT3. Daidzein did not show inhibitory effects on milk production. The effects of genistein and equol were also confirmed in lactating mammary epithelial cells (MECs), which were cultured in the presence of soy isoflavones and equol at physiological concentrations for 7 days. These findings indicate that genistein, daidzein, and equol influence milk production in MECs in vivo and in vitro in distinctly different ways.

Soy Phytoestrogens Do Not Fully Reverse Changes in Rat Pituitary Castration Cells: Unbiased Stereological Study

The aim of the study was to examine the potential of the principal soy isoflavones, genistein and daidzein, or isoflavone rich soy extract to recover pituitary castration cells in orchidectomized adult male rats in comparison with the effects of estradiol. Two weeks post orchidectomy (Orx), animals received estradiol-dipropionate, genistein, daidzein or soy extract subcutaneously for 3 weeks. Control sham-operated (So) and Orx rats received just the vehicle. Changes in the volumes of pars distalis, of individual follicle-stimulating hormone (FSH) and luteinizing hormone (LH) containing cells, their volume, numerical density and number were determined by unbiased design-based stereology. The intracellular content of βFSH and βLH was estimated by relative intensity of fluorescence (RIF). Orchidectomy increased all examined stereological parameters and RIF. Compared to Orx, estradiol increased the volume of pars distalis, but reversed RIF and all morphometric parameters of gonadotropes to the level of So rats, except their number. Treatments with purified isoflavones and soy extract decreased RIF to the control So level, expressing an estradiol-like effect. However, the histological appearance and morphometrical features of gonadotropes did not follow this pattern. Genistein increased the volume of pars distalis, decreased the volume density of LH-labeled cells and raised the number of gonadotropes. Daidzein decreased the cell volume of gonadotropic cells but increased their number and numerical density. Soy extract induced an increase in number and numerical density of FSH-containing cells. Therefore, it can be concluded that soy phytoestrogens do not fully reverse the Orx-induced changes in pituitary castration cells. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.

The Morpho-Functional Parameters of Rat Pituitary Hormone Producing Cells After Genistein Treatment

Phytoestrogens are a diverse group of steroid–like compounds that occur naturally in many plants. There are various types of phytoestrogens, including the best-researched isoflavones which are commonly found in soy. The consumption of soy products has many health benefits, including protection against breast cancer, prostate cancer, menopausal symptoms, heart disease and osteoporosis. In contrast, use of hormonally active compounds-isoflavones may unfortunately interfere with the endocrine system and can have far-reaching consequences. Genistein, the most abundant soy-bean derived isoflavone, possesses a ring system similar to estrogens and acts through an estrogen receptor (ER)-mediated mechanism, by increasing or decreasing the transcription of ER-dependent target genes. Also, genistein can act on cells through ER non-dependent mechanisms, such as tyrosine kinase inhibitor. The neuroendocrine systems are responsible for the control of homeostatic processes in the body, including reproduction, growth, metabolism and energy balance, and stress responsiveness. It is well known, that estrogen is important for development of the neuroendocrine system in both sexes. At the pituitary level, estrogen is known to affect the regulation of all hormone producing (HP) cells, by direct and/or indirect mechanisms. Due to structural and functional resemblance to estrogen, the question may arise of whether and how genistein affects the morphofunctional features of pituitary HP cells. This review deals with the consequences of genistein’s effects on morphological, stereological and hormonal features of HP cells within the anterior pituitary gland. Transparency on this issue is needed because isoflavones are presently highly consumed. Inter alia, genistein as well as other isoflavones, are present in various dietary supplements and generally promoted as an accepted alternative to estrogen replacement therapy. Potential isoflavone biomedical exploitation is not only limited to estrogen replacement therapy, so it should be treated in a wider context of different ageing symptoms remediation.

Effects of Trifolium alexandrinum phytoestrogens on oestrous behaviour, ovarian activity and reproductive performance of ewes during the non-breeding season

Phytoestrogens are classified as naturally occurring endocrine disrupting chemicals that may affect reproductive performance of farm animals. To investigate the effects of Berseem clover phytoestrogens on reproductive performance of seasonal anoestrus ewes, twenty four late pregnant Rahmani ewes were fed either Berseem clover or maize silage (n = 12/treatment). Treatment started 2 months prepartum and continued until oestrous induction (week 8 postpartum), using the CIDR-eCG based protocol, and early pregnancy. Throughout the 2-8 weeks postpartum, oestrous rate and ovarian activity were not affected by treatment. After oestrous induction, ewes in both groups expressed comparable oestrous rates; however feeding Berseem clover extended (P < 0.05) interval to oestrus (57.00 compared with 42.54 h) and shortened (P < 0.05) oestrous duration (20.0 compared with 34.90 h). Feeding Berseem clover did not affect follicular activity except the number of medium follicles, which was less (P < 0.05) on day of oestrus (Day 0). Feeding maize silage increased (P < 0.05) the total number of follicles and number of small and medium follicles the day before oestrus (Day -1). On Day 0, the greater total number of follicles was due to the greater (P < 0.05) number of medium follicles that was associated with less number of small follicles. Although, the number and diameter of corpora lutea (CLs) were not affected by treatment, serum P₄ concentration was greater (P < 0.05) for ewes fed maize silage than for those fed Berseem clover. Fecundity and litter size tended to be greater (about 35%; P = 0.132 and 0.085, respectively) in the maize silage fed ewes. In conclusion, feeding Berseem clover throughout seasonal anoestrus disrupted aspects of behavioural oestrus and there was less luteal P₄ synthesis and fecundity of ewes.

Breastfeeding: A Review of Its Physiology and Galactogogue Plants in View of Traditional Persian Medicine

INTRODUCTION

The beneficial effects of breastfeeding for the infant and mother are well recognized. Many natural products are reputed to be galactogogue agents in major Traditional Persian Medicine (TPM) textbooks. The aim of this study is to review those medicinal plants that are reported to be effective in increasing breast milk in TPM and to compare the data from TPM texts with the findings of modern pharmacological and clinical research.

MATERIALS AND METHODS

Data on the medicinal plants used to increase breast milk were obtained from major TPM textbooks. A detailed search in PubMed, Science Direct, Scopus, Google Scholar, and Web of Science databases was performed to confirm the effects of medicinal plants mentioned in TPM on lactation in view of the identified pharmacological actions.

RESULTS

Foeniculum vulgare, Anethum graveolens, Pimpinella anisum, Nigella sativa, and Vitex agnus-castus are among the most effective galactogogue TPM plants. Many pharmacologically relevant activities have been reported for these herbs.

CONCLUSION

The use of traditional knowledge can pave the way toward finding effective phytopharmaceuticals for increasing breast milk.

Diverse effects of phytoestrogens on the reproductive performance: cow as a model

Phytoestrogens, polyphenolic compounds derived from plants, are more and more common constituents of human and animal diets. In most of the cases, these chemicals are much less potent than endogenous estrogens but exert their biological effects via similar mechanisms of action. The most common source of phytoestrogen exposure to humans as well as ruminants is soybean-derived foods that are rich in the isoflavones genistein and daidzein being metabolized in the digestive tract to even more potent metabolites-para-ethyl-phenol and equol. Phytoestrogens have recently come into considerable interest due to the increasing information on their adverse effects in human and animal reproduction, increasing the number of people substituting animal proteins with plant-derived proteins. Finally, the soybean becomes the main source of protein in animal fodder because of an absolute prohibition of bone meal use for animal feeding in 1995 in Europe. The review describes how exposure of soybean-derived phytoestrogens can have adverse effects on reproductive performance in female adults.

Estrogenic environmental endocrine-disrupting chemical effects on reproductive neuroendocrine function and dysfunction across the life cycle

Endocrine disrupting chemicals (EDCs) are natural or synthetic compounds that interfere with the normal function of an organism's endocrine system. Many EDCs are resistant to biodegradation, due to their structural stability, and persist in the environment. The focus of this review is on natural and artificial EDCs that act through estrogenic mechanisms to affect reproductive neuroendocrine systems. This endocrine axis comprises the hypothalamic gonadotropin-releasing hormone (GnRH), pituitary gonadotropins, and gonadal steroid hormones, including estrogens. Although it is not surprising that EDCs that mimic or antagonize estrogen receptors may exert actions upon reproductive targets, the mechanisms for these effects are complex and involve all three levels of the hypothalamic-pituitary-gonadal (HPG) system. Nevertheless, considerable evidence links exposure to estrogenic environmental EDCs with neuroendocrine reproductive deficits in wildlife and in humans. The effects of an EDC are variable across the life cycle of an animal, and are particularly potent when exposure occurs during fetal and early postnatal development. As a consequence, abnormal sexual differentiation, disrupted reproductive function, or inappropriate sexual behavior may be detected later in life. This review will cover the effects of two representative classes of estrogenic EDCs, phytoestrogens and polychlorinated biphenyls (PCBs), on neuroendocrine reproductive function, from molecules to behavior, across the vertebrate life cycle. Finally, we identify the gaps of knowledge in this field and suggest future directions for study.

Introduction: neurobiological impact of environmental estrogens

This paper provides an introduction to a special issue dedicated to the action of environmental estrogens on neural circuits and behavior. The problem of endocrine disrupting chemicals (EDCs), i.e. chemicals that have the capacity to interfere with the endocrine system, has gained increasing attention as it has become clear that these environmental contaminants may be active in humans, as well as in wildlife and domestic animal species. The majority of the early investigations were aimed at the discovery of the toxicological effects of the EDCs, but biomedical observations were among some of the first indications that estrogenic compounds may exert deleterious effects, even some time after exposure. The data derived from women exposed prenatally to diethylstilbesterol provided powerful evidence for long-term effects and endocrine disruption associated with selected compounds. The examination of wild animal populations exposed to industrial chemicals showed that the chemical exposure, though nonlethal, left the individual impaired or even incapable of reproducing. Among the multiple targets of the action of EDCs, several researches performed in recent years have investigated subtle modifications of the animal behaviors (reproductive, aggressive) that are likely to be related to alterations of specific neural pathways. We have, therefore, focused here on the behavioral studies as one of the more powerful tools to investigate EDCs effects on specific neural circuits.

Effects of intracerebroventricular infusion of genistein on the secretory activity of the GnRH/LH axis in ovariectomized ewes

Phytoestrogens, plant derived estrogen like-compounds exert numerous effects on the reproductive functions of animals. The present study was designed to demonstrate if exogenous genistein infused during the breeding season into the third ventricle of the brain of ovariectomized ewes could affect the secretory activity of the GnRH/LH axis. Two-year-old ovariectomized ewes (n=8) were infused with vehicle (control, n=3) or genistein (10 microg/100 microl/h, n=5) into the third ventricle. The infusions were done from 10.00 to 14.00 h and blood samples collection was performed this day up to 20.00 h and next day from 8.00 to 10.00 h. The animals were slaughtered, thereafter. Immunoreactive (IR) GnRH neurons in the hypothalamus and LH cells in the adenohypophysis were localized by immunohistochemistry. Messenger RNA analyses were performed by nonisotope in situ hybridization using sense and anti-sense riboprobes produced from beta subunits of LH cDNA clones. Plasma LH concentrations were measured by radioimmunoassay. Immunohistochemical analysis revealed that genistein infusion affected the morphology of GnRH neurons evoking a visualization of long axons in the GnRH perikarya and visibly diminished IR GnRH stores in the median eminence. The number of IR LH cells and IR material stored in the adenohypophyses increased in genistein-infused animals, which was confirmed by statistical analysis (P<0.001). The in situ hybridization analyses showed in these ewes the increase of mRNA LHbeta hybridization signal. The changes in LH release in response to genistein infusion had a biphasic character: it decreased within 6 h after infusion and increased 24 h later. Mean concentration of LH and amplitude of pulses measured from the beginning of infusion up to end of the experiment were significantly higher (P<0.05) in genistein-infused ewes compared to vehicle-treatment. In conclusion, our data show that genistein, a phytoestrogen, may effectively modulate GnRH and LH secretion in OVX ewes by acting directly on the CNS. The biphasic character of the LH response is similar to that of estradiol during the breeding season in the ewes.

Effects of intracerebroventricular infusion of genistein on gonadotrophin subunit mRNA and immunoreactivity of gonadotrophins and oestrogen receptor-alpha in the pituitary cells of the anoestrous ewe

The present study was designed to demonstrate whether genistein, a synthetic phytoestrogen, infused into the third ventricle of the brain could affect the gonadotrophic cells regarding the presence of oestrogen receptor-alpha immunoreactivity and gonadotrophin subunit mRNA hybridising reaction in the ewe. Ewes (n=7), aged 2 years, in early anoestrous season were infused with Ringer-Locke solution (control, n=3) or 10 microg/100 microl/h of genistein (n=4) into the third ventricle over a 5 h period and slaughtered the following morning. Immunoreactivity of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and oestrogen receptor-alpha (ERalpha) was determined in the adenohypophysis by immunohistochemistry using antibodies raised against LHbeta, FSHbeta, and ERalpha. Messenger RNA analyses were performed by non-isotope in situ hybridisation using sense and antisense riboprobes produced from beta subunits of LH and FSH cDNA clones. Computer image analysis was used to determine the percent of cells exhibiting immunohistochemical and/or hybridising reaction. It was found that in ewes infused with genistein, the percentage of LH-positive cells and the density of immunoreactive-LHbeta material decreased significantly (P<or=0.001), but the percentage of mRNA LHbeta-expressing cells and the intensity of the hybridisation signal increased significantly (P<or=0.001), compared to the vehicle-infused animals. The genistein infusions had no effect on the immunoreactivity of FSH cells or on the expression of mRNA for FSHbeta. The percentage of ERalpha-positive cells increased significantly after genistein infusions (P<or=0.001) and this increase was significant in the LH but not in FSH cells (P<or=0.001). In conclusion, we suggest that genistein can stimulate the expression of immunoreactive ERalpha in the pituitary LH-cells but not in FSH-cells and change the endocrine activity of LH-producing cells of anoestral ewes.