Effects of genistein on gonadotropic cells in immature female rats

Impact of Physiologically Relevant Genistein Exposure at Different Time Windows on Puberty Onset and Neuroendocrine Function in Female Rats

SCOPE

Puberty timing, critical for adulthood wellbeing, is influenced by the environment, life-style, and diets. However, differential puberty-interfering effects of soy and soy isoflavone are observed in both epidemiological and toxicological studies. Additionally, their impact on neuroendocrine function at various pre-pubertal developmental windows is unclear.

METHODS AND RESULTS

This study investigates the effect of genistein, a typical soy isoflavone, at neonatal, lactational, and post-weaning stages on the time of vaginal opening and determines the levels of neuroendocrine factors in female rats using immunofluorescence, immunochemistry, and enzyme-linked immunosorbent assays. A physiologically relevant dosage (10 mg kg^-1 ) is used to resemble human exposure. The results show that genistein exposure at lactational stage significantly accelerates vaginal opening time, marginally increases hypothalamic gonadotropin-releasing hormone (GnRH) secretion, significantly enhances kisspeptin receptor expression, and markedly elevates blood levels of GnRH, luteinizing hormone, and follicle-stimulating hormone, while neonatal and post-weaning exposures do not induce significant alternations.

CONCLUSION

Lactational stage may be an important window for genistein to impact reproductive development and neuroendocrine regulations.

Effects of Phytoestrogens on the Developing Brain, Gut Microbiota, and Risk for Neurobehavioral Disorders

Many pregnant and nursing women consume high amounts of soy and other plant products that contain phytoestrogens, such as genistein (GEN) and daidzein. Infants may also be provided soy based formulas. With their ability to bind and activate estrogen receptors (ESR) in the brain, such compounds can disrupt normal brain programming and lead to later neurobehavioral disruptions. However, other studies suggest that maternal consumption of soy and soy based formulas containing such phytoestrogens might lead to beneficial behavioral effects. Select gut microbes might also convert daidzein and to a lesser extent genistein to even more potent forms, e.g., equol derivatives. Thus, infant exposure to phytoestrogens may result in contrasting effects dependent upon the gut flora. It is also becoming apparent that consumption or exposure to these xenoestrogens may lead to gut dysbiosis. Phytoestrogen-induced changes in gut bacteria might in turn affect the brain through various mechanisms. This review will consider the evidence to date in rodent and other animal models and human epidemiological data as to whether developmental exposure to phytoestrogens, in particular genistein and daidzein, adversely or beneficially impact offspring neurobehavioral programming. Consideration will be given to potential mechanisms by which such compounds might affect neurobehavioral responses. A better understanding of effects perinatal exposure to phytoestrogen can exert on brain programming will permit pregnant women and those seeking to become pregnant to make better-educated choices. If phytoestrogen-induced gut dysbiosis contributes to neurobehavioral disruptions, remediation strategies may be designed to prevent such gut microbiota alterations and thereby improve neurobehavioral outcomes.

Early genistein exposure of California mice and effects on the gut microbiota-brain axis

Human offspring encounter high amounts of phytoestrogens, such as genistein (GEN), through maternal diet and soy-based formulas. Such chemicals can exert estrogenic activity and thereby disrupt neurobehavioral programming. Besides inducing direct host effects, GEN might cause gut dysbiosis and alter gut metabolites. To determine whether exposure to GEN affects these parameters, California mice (Peromyscus californicus) dams were placed 2 weeks prior to breeding and throughout gestation and lactation on a diet supplemented with GEN (250 mg/kg feed weight) or AIN93G phytoestrogen-free control diet (AIN). At weaning, offspring socio-communicative behaviors, gut microbiota and metabolite profiles were assayed. Exposure of offspring to GEN-induced sex-dependent changes in gut microbiota and metabolites. GEN exposed females were less likely to investigate a novel female mouse when tested in a three-chamber social test. When isolated, GEN males and females exhibited increased latency to elicit their first call, suggestive of reduced motivation to communicate with other individuals. Correlation analyses revealed interactions between GEN-induced microbiome, metabolome and socio-communicative behaviors. Comparison of GEN males with AIN males revealed the fraction of calls above 20 kHz was associated with daidzein, α-tocopherol, Flexispira spp. and Odoribacter spp. Results suggest early GEN exposure disrupts normal socio-communicative behaviors in California mice, which are otherwise evident in these social rodents. Such effects may be due to GEN disruptions on neural programming but might also be attributed to GEN-induced microbiota shifts and resultant changes in gut metabolites. Findings indicate cause for concern that perinatal exposure to GEN may detrimentally affect the offspring microbiome-gut-brain axis.

Immunohistomorphometric Changes of The Pituitary Gonadotropic Cells After Testosterone Application in a Rat Model of the Andropause

Andropause, the culminating phase of male ageing, is characterized by deregulation of the hypothalamic-pituitarygonadal axis and low circulating free testosterone. The aim of this study was to investigate the immunohistomorphometric characteristics of the pituitary gonadotropic i.e. follicle-stimulating hormone (FSH) and the luteinizing hormone (LH) producing cells after testosterone application in a rat model of the andropause. Middle-aged Wistar rats were divided into orchidectomized (ORX; n=8) and testosterone treated orchidectomized (ORX+T; n=8) groups. Testosterone propionate (5 mg/kg b.m./day) was administered for three weeks, while the ORX group received the vehicle alone. Immunohistochemically stained FSH and LH cells underwent morphometric and optical density-related analysis, while circulating concentrations of the sex steroids were measured by immunoassays. Serum concentrations of testosterone and estradiol were significantly (p<0.05) increased by 24 and 2.7 fold respectively, compared to the ORX group. The volume of FSH and LH cells was significantly (p<0.05) decreased by 51.3% and 56.6% respectively, in comparison with ORX rats. Relative volume density of FSH and LH cells was also significantly (p<0.05) decreased by 54.0% and 72.8% respectively, compared to the ORX group. Results related to the optical density of gonadotropic cells (reflecting their hormonal content) were in line with the morphometric findings i.e. this parameter of FSH and LH cells was significantly (p<0.05) decreased by 25.7% and 16.2% respectively, in comparison with ORX rats. Conclusion: In conclusion, applied testosterone increased the serum concentrations of sex steroids, as well as it decreased morphometric parameters and optical density of gonadotropic cells in ORX rats.

Myrianthus arboreus P. Beauv (Cecropiaceae) Extracts Accelerates Sexual Maturation, and Increases Fertility Index and Gestational Rate in Female Wistar Rats

Background: Despite the wide use of leaves of Myrianthus arboreus (Cecropiaceae) in several African countries including Cameroon as food and against amenorrhea and female infertility, it has never been tested for this purpose. Methods: Using immature female Wistar rats, the impact of M. arboreus on the sexual maturation parameters (vaginal opening, ovarian relative weight and follicle maturation, gonadotropins and ovarian hormones serum levels) and fertility index has been evaluated through a 30-day oral administration of aqueous and methanol extracts of leaves at the doses of 20, 110 and 200 g/kg/day. Results: Aqueous extract increased the ovarian relative weight (p < 0.001), progesterone (p < 0.001) and gonadotropins (p < 0.001) serum levels, and induced the maturation of ovarian follicles. The methanol extract additionally induced an early vaginal opening (p < 0.001), uterine growth (p < 0.01) and increased estradiol (p < 0.001) serum levels. The fertility index generally increased following treatments, while the gestation rate remained almost unaffected except at the highest tested dose of M. arboreus extracts where lowest values were observed. Conclusion: Globally, M. arboreus induced an early puberty onset and an increased fertility rate validating at least in part its traditional use for female infertility.

Morphometric analysis of the folliculostellate cells and luteinizing hormone gonadotropic cells of the anterior pituitary of the men during the aging process

The aim of this research was to quantify the changes in the morphology and density of the anterior pituitary folliculostellate (FS) and luteinizing hormone (LH) cells. Material was tissue of the pituitary gland of the 14 male cadavers. Tissue slices were immunohistochemically stained with monoclonal anti-LH antibody and polyclonal anti-S100 antibody for the detection of LH and FS cells, respectively. Digital images of the stained slices were afterwards morphometrically analyzed by ImageJ. Results of the morphometric analysis showed significant increase of the FS cells volume density in cases older than 70 years. Volume density of the LH cells did not significantly change, whereas their area significantly increased with age. Nucleocytoplasmic ratio of the LH cells gradually decreased and became significant after the age of 70. Finally, volume density of the FS cell significantly correlated with LH cells area and nucleocytoplasmic ratio. From all above cited, we concluded that in men, density and size of the FS cells increase with age. Long-term hypertrophy of the LH cells results in their functional decline after the age of 70. Strong correlation between FS cells and LH cells morphometric parameters might point to age-related interaction between these two cell groups.

Effects of soy phytoestrogens on pituitary-ovarian function in middle-aged female rats

The aim of this study was to assess the effects of genistein (G) and daidzein (D) on the histological, hormonal, and functional parameters of the pituitary-ovarian axis in middle-aged female rats, and to compare these effects with the effects of estradiol (E), commonly used in the prevention and treatment of menopausal symptoms. Middle-aged (12 month old) Wistar female rats subcutaneously received 35 mg/kg of G, or 35 mg/kg of D, or 0.625 mg/kg of E every day for 4 weeks. Each of the treated groups had a corresponding control group. An intact control group was also established. G and D did not change the intracellular protein content within gonadotropic and lactotropic cells, but vacuolization was observed in all the cell types. In contrast, E caused an inhibition of gonadotropic and stimulation of lactotropic cells. Also, ovaries of middle-aged female rats exposed to G or D have more healthy primordial and primary follicles and less atretic follicles. E treatment in the ovaries had a mostly negative effect, which is reflected by the increased number of atretic follicles in all tested classes. G and D provoked decrease in CuZnSOD and CAT activity, while E treatment increased MnSOD and decreased CuZnSOD and GSHPx activity. All the treatments increased serum estradiol and decreased testosterone levels, while D and E increased the serum progesterone level. In conclusion, soy phytoestrogens exhibited beneficial effects on pituitary-ovarian function in middle-aged female rats, as compared to estradiol.

Soy extract-dependent changes in morphofunctional parameters of the pituitary corticotropes in adult rats

Numerous studies have established a link between estrogen levels and activity of the hypothalamic pituitary adrenal (HPA) system. Considering the "weak estrogenic" effect of soy isoflavones, this study was designed to evaluate the influence of soy extract treatment on some morphofunctional parameters of rat pituitary corticotropes in vivo. Adult male orchidectomized Wistar rats received estradiol-dipropionate or soy extract in oil/ethanol solvent subcutaneously for 3 weeks. Both controls, sham-operated (So) and orchidectomized (Orx) rats, were injected with solvent, in the same regime. Changes in pituitary volume, total volume, total number and volume of individual corticotropes were evaluated stereologically, while ACTH levels were determined biochemically. In comparison with So rats, estradiol treatment provoked increases (p<0.05) of: ACTH level (166%), pituitary weight (167%) and volume (102%), total volume (20%) and total number of corticotropes (18%). In comparison to Orx, following estradiol treatment elevation (p<0.05) of: ACTH level (69%), pituitary weight (131%) and volume (82%), total (30%) and individual volume (29%) of corticotropes was observed. Soy extract treatment led to enhancement (p<0.05) of: ACTH level (28%), total (25%) and individual volume (20%) of corticotropes. It can be concluded that soy extract acts in a similar way to estradiol, but the increased activity of corticotropes was weaker.