Postnatal genistein administration selectively abolishes sexual dimorphism in specific hypothalamic dopaminergic system in mice

Infant mice fed soy-based formulas exhibit alterations in anxiety-like behaviours and the 5-HT system

Genistein (GEN) is a phytoestrogen with oestrogen-like activity found in many plants. Classified as an endocrine disruptor, GEN is potentially hazardous, particularly during developmental stages. It induces alterations in anxious behaviour, fertility, and energy metabolism, alongside modifications in specific brain circuits. As the serotonin (5-HT) system is critically involved in many of these behaviours, we hypothesised that some of GEN's behavioural effects might results from disruptions in the development of the 5-HT system. To test this, we examined the impact of early postnatal exposure to GEN at a dose of 50 mg/kg body weight, mimicking the exposure level of infants consuming soy-based formulas, on anxiety-related behaviours and 5-HT neuronal populations in the raphe nucleus. Male and female CD1 mice were treated orally with GEN or a vehicle during the first 8 days of life. On postnatal day 60, one cohort underwent anxiety behaviour testing, while another was euthanised for immunohistochemical analysis. Behavioural testing revealed that male control mice exhibited higher anxiety levels than females, whereas GEN exposure produced sex-specific effects: anxiolytic in males and anxiogenic in females. Immunohistochemical analysis of the raphe nuclei demonstrated significant alterations in 5-HT neuronal numbers in GEN-treated animals. Specifically, GEN exposure affected dorsal and median raphe 5-HT neuronal populations in a sexually dimorphic manner, with females showing a reduction and males an increase in 5-HT neurones compared to controls. These findings indicate that the regulation of anxiety-related behaviours and the 5-HT system are key targets of early phytoestrogen exposure at levels comparable to those in soy-based infant formulas.

Genotoxic and genoprotective effects of phytoestrogens: a systematic review

Phytoestrogens are xenoestrogens found in plants with a myriad of health benefits. However, various studies reported the genotoxic effects of these substances. Thus, we reviewed in vitro and in vivo studies published in PubMed, Scopus, and Web of Science to evaluate the genotoxic and the genoprotective potential of phytoestrogens. Only studies written in English and intended to study commercially available phytoestrogens were included. The screening was performed manually. Moreover, the underlying mechanism of action of phytoestrogens was described. Around half of those studies (43%) reported genoprotective results. However, several studies revealed positive results for genotoxicity with specific model organisms and with dose/concentration dependence. The assessment of the selected articles showed substantial differences in the used concentrations and a biphasic response was recorded in some phytoestrogens. As far as we know, this is the first study to assess the genotoxic and genoprotective effects of phytoestrogens systematically.

Genistein early in life Modifies the arcuate nucleus of the hypothalamus morphology differentially in male and female rats

In the present work we analyzed the effects of postnatal exposure to two doses of genistein (10 μg/g or 50 μg/g) from postnatal (P) day 6 to P13, on the morphology of the arcuate nucleus (Arc). The analyses of Arc coronal brain sections at 90 days showed that the ArcMP had higher values in volume, Nissl-stained neurons and GPER-ir neurons in males than in females and the treatment with genistein abolished these sex differences in most of the parameters studied. Moreover, in males, but not in females, the GPER-ir neurons decreased in the ArcMP but increased in the ArcL with both doses of genistein. In the ArcLP, GPER-ir population increased with the lowest doses and decreased with the highest one in males. Our results confirm that the Arc subdivisions have differential vulnerability to the effects of genistein during development, depending on which neuromorphological parameters, dose and sex are analyzed.

Environmental contaminants, endocrine disruption, and transgender: Can "born that way" in some cases be toxicologically real?

Gender is viewed by many as strictly binary based on a collection of body traits typical of a female or male phenotype, presence of a genotype that includes at least one copy of a Y chromosome, or ability to produce either egg or sperm cells. A growing non-binary view is that these descriptors, while compelling, may nonetheless fail to accurately capture an individual's true gender. The position of the American Psychological Association (APA) agrees with this view and is that transgender people are a defendable and real part of the human population. The considerable diversity of transgender expression then argues against any unitary or simple explanations, however, prenatal hormone levels, genetic influences, and early and later life experiences have been suggested as playing roles in development of transgender identities. The present review considers existing and emerging toxicologic data that may also support an environmental chemical contribution to some transgender identities, and suggest the possibility of a growing nonbinary brain gender continuum in the human population.

Greater Consumption of Total and Individual Lignans and Dietary Fibers Were Significantly Associated with Lowered Risk of Hip Fracture-A 1:1 Matched Case-Control Study among Chinese Elderly Men and Women

The study aims to examine the association of dietary intake of lignans with the risk of hip fractures in Chinese older adults. This was a 1:1 age- and gender- matched case−control study. Dietary survey was conducted by face-to-face interviews using a 79-item validated food frequency questionnaire. Habitual intake of total and individual lignans (matairesinol, secoisolariciresinol, pinoresinol, and lariciresinol) was estimated based on the available lignans databases. Conditional logistic regression was used to examine the relationship of dietary total and individual lignans, lignan-rich foods (vegetables, fruits, nuts, and cereals) and dietary fibers with the risk of hip fracture. A total of 1070 pairs of hip fracture incident cases and controls were recruited. Compared with the lowest quartile, the highest quartile group showed a reduced hip fracture risk by 76.3% (0.237, 95% CI: 0.103−0.544, Ptrend < 0.001) for total lignans, and 62.5% (0.375, 95% CI: 0.194−0.724, Ptrend = 0.001) for dietary fibers. Similar findings were observed for individual lignans, the estimated enterolactone level, as well as lignans from vegetables and nuts. We concluded that greater consumption of total and individual lignans, and lignan-rich foods were significantly associated with decreased risk of hip fracture.

Early Postnatal Genistein Administration Affects Mice Metabolism and Reproduction in a Sexually Dimorphic Way

The phytoestrogen genistein (GEN) may interfere with permanent morphological changes in the brain circuits sensitive to estrogen. Due to the frequent use of soy milk in the neonatal diet, we aimed to study the effects of early GEN exposure on some physiological and reproductive parameters. Mice of both sexes from PND1 to PND8 were treated with GEN (50 mg/kg body weight, comparable to the exposure level in babies fed with soy-based formulas). When adult, we observed, in GEN-treated females, an advanced pubertal onset and an altered estrous cycle, and, in males, a decrease of testicle weight and fecal testosterone concentration. Furthermore, we observed an increase in body weight and altered plasma concentrations of metabolic hormones (leptin, ghrelin, triiodothyronine) limited to adult females. Exposure to GEN significantly altered kisspeptin and POMC immunoreactivity only in females and orexin immunoreactivity in both sexes. In conclusion, early postnatal exposure of mice to GEN determines long-term sex-specific organizational effects. It impairs the reproductive system and has an obesogenic effect only in females, which is probably due to the alterations of neuroendocrine circuits controlling metabolism; thus GEN, should be classified as a metabolism disrupting chemical.

Genistein during Development Alters Differentially the Expression of POMC in Male and Female Rats

Phytoestrogens are considered beneficial for health, but some studies have shown that they may cause adverse effects. This study investigated the effects of genistein administration during the second week of life on energy metabolism and on the circuits regulating food intake. Two different genistein doses, 10 or 50 µg/g, were administered to male and female rats from postnatal day (P) 6 to P13. Physiological parameters, such as body weight and caloric intake, were then analyzed at P90. Moreover, proopiomelanocortin (POMC) expression in the arcuate nucleus (Arc) and orexin expression in the dorsomedial hypothalamus (DMH), perifornical area (PF) and lateral hypothalamus (LH) were studied. Our results showed a delay in the emergence of sex differences in the body weight in the groups with higher genistein doses. Furthermore, a significant decrease in the number of POMC-immunoreactive (POMC-ir) cells in the Arc in the two groups of females treated with genistein was observed. In contrast, no alteration in orexin expression was detected in any of the structures analyzed in either males or females. In conclusion, genistein can modulate estradiol's programming actions on the hypothalamic feeding circuits differentially in male and female rats during development.

The influence of phytoestrogens on different physiological and pathological processes: An overview

Functional foods have nutritional properties and organic functions, which are beneficial to health. Certain types of functional food components are so-called phytoestrogens, non-steroidal compounds derived from the metabolism of precursors contained in plants, which originate secondary metabotypes known to induce biological responses and by mimicry or modulating the action of endogenous estrogen. These molecules are involved in several physiological and pathological processes related to reproduction, bone remodeling, skin, cardiovascular, nervous, immune systems, and metabolism. This review aimed to present an overview of phytoestrogens regarding their chemical structure, actions, and effects in the organism given several pathologies. Several studies have demonstrated beneficial phytoestrogen actions, such as lipid profile improvement, cognitive function, menopause, oxidative stress, among others. Phytoestrogens effects are not completely elucidated, being necessary future research to understand the exact action mechanisms, whether they are via estrogen receptor or whether other hidden mechanisms produce these effects. Thus, this review makes a general approach to the phytoestrogen actions, beneficial effects, risk and limitations. However, the complexities of biological effects after ingestion of phytoestrogens and the differences in their metabolism and bioavailability indicate that interpretation of either risk or benefits needs to be made with caution.