Phytoestrogen Diet Research Articles

Effects of phytoestrogens on testosterone secretion by Leydig cells from Biłgoraj ganders ( Anser anser )

1. The aim of this study was to examine ganders at different stages of the reproductive season and the effect of: (1) diets with high phytoestrogen content and (2) in vitro phytoestrogen treatment on testosterone secretion by isolated Leydig cells. 2. Thirty-six male Biłgoraj geese were fed control diets with low phytoestrogen content (containing grass meal) and diets with high phytoestrogens (containing alfalfa meal and soy). 3. Testes were obtained from both groups of ganders at three different times of the breeding season: peak of reproductive activity (March), second half of reproductive activity (May) and beginning of photorefractoriness (July). 4. Isolated Leydig cells were incubated with LH as well as genistein, daidzein, equol and coumestrol and the concentration of testosterone in the medium was determined by radioimmunoassay. 5. The mean weight of testes from ganders in May and July decreased relative to their weights in March, but no significant differences among experimental groups were noted. 6. No differences were observed in basal and LH-stimulated testosterone secretion by Leydig cells of ganders fed the control diets and the diets with higher phytoestrogen content. In July, LH did not stimulate testosterone secretion in either group. In vitro treatment with genistein, daidzein and equol (5 and 50 µM) inhibited basal and LH-stimulated testosterone production by Leydig cells from both groups. Coumestrol (5 and 50 µM) inhibited basal testosterone secretion only in March in the control group. 7. Dietary exposure to phytoestrogens had a slight effect on in vitro testicular secretion in ganders. In vitro treatment with phytoestrogen inhibited testosterone production by Leydig cells. Genistein showed the strongest effect and coumestrol had the weakest influence on testicular secretion.

250. Adult exposure to dietary phytoestrogens reduces fertility of male rats

Phytoestrogens are plant-derived compounds that are particularly abundant in soy-based foods. Exposure to exogenous oestrogenic chemicals has been implicated in declining male fertility. The aim of this study is to deduce whether adult phytoestrogen exposure affects the reproductive function of male rats, and by what mechanisms phytoestrogens may be acting. Six male rats were transferred from a low soy diet (control) to an experimental high soy diet, while nine males remained on the control diet. On days 3, 6 and 12 all males were mated and litter sizes recorded. A second group of male rats kept on the same dietary regimen were killed after 3, 6 or 12 days on the diets. The epididymides were collected from the rats. Real-time PCR was performed to measure mRNA quantities of oestrogen receptors alpha (ERα) and beta (ERβ), and androgen receptor (AR). The TBARS assay for lipid peroxidation was performed on epididymal sperm samples from rats fed the high or low phytoestrogen diet for 3 days. The average litter size following 3 days on the high soy diet was significantly lower than that for rats maintained on the control diet. Litter sizes returned to control levels by day 12. ERα and AR expression decreased in the cauda region of the epididymis following 3 days on the high soy diet, but returned to control levels by day 6. Lipid peroxidation of epididymal sperm was increased in rats fed the high phytoestrogen diet for 3 days. Short-term exposure to high phytoestrogen levels transiently reduces male fertility, and alters hormone receptor expression. Endocrine disruption may impair fertility by reducing antioxidant protection of sperm stored in the epididymis.

Effects of a diet rich in phytoestrogens on prostate-specific antigen and sex hormones in men diagnosed with prostate cancer

Objectives To determine the effects of diets rich in soy and linseed compared with a control diet on biochemical markers of prostate cancer in men diagnosed with prostate cancer. Methods Twenty-nine men diagnosed with prostate cancer and scheduled to undergo a radical prostatectomy were randomized to one of three groups: soy (high phytoestrogen), soy and linseed (high phytoestrogen), or wheat (low phytoestrogen). A bread was specially manufactured to incorporate 50 g of heat-treated (HT) soy grits or 50 g of HT soy grits and 20 g of linseed as part of the study participant's daily diet. Baseline and preoperative levels of prostate-specific antigen (PSA), free PSA, testosterone, sex hormone-binding globulin, free androgen index, and dihydrotestosterone were measured. Results Statistically significant differences were detected between the HT soy grits group and the control wheat group for the percentage of change in total PSA (−12.7% versus 40%, P = 0.02) and the percentage of change in free/total PSA ratio (27.4% versus −15.6%, P = 0.01); and between the HT soy grits group and the HT soy grits and linseed group for the percentage of change in free androgen index (16.4% versus −15.5%, P = 0.04) and the percentage of change in free/total PSA ratio (27.4% versus −10%, P = 0.007). Conclusions The data from this study indicate that a daily diet containing four slices of a bread rich in HT soy grits favorably influences the PSA level and the free/total PSA ratio in patients with prostate cancer. This work provides some evidence to support epidemiologic studies claiming that male populations who consume high phytoestrogen diets have a reduced risk of prostate cancer development and progression.

158. Effects of phytoestrogens on the ovarian and pituitary phenotypes of oestrogen deficient female aromatase knockout mice

Phytoestrogens can induce both estrogen agonistic and antagonistic effects, depending on the tissue, estrogen receptor content and endogenous levels of estrogen. Dietary phytoestrogens are promoted as alternatives to synthetic estrogens for hormone replacement therapy, however their effects on the reproductive axis have not been exhaustively studied in vivo. Female aromatase knockout mouse (ArKO) mice are estrogen-free, and anovulatory with a block in folliculogenesis, hemorrhagic cysts and development of Sertoli cells within their ovaries. We evaluated the ArKO mouse as a model to test the effects of phytoestrogen-supplemented diets on the reproductive organ weights, ovarian morphology, gonadotropin levels and the transcript levels of ovarian somatic cell and steroidogenic markers. The extent to which phytoestrogens either as soyfree or soymeal diet or genistein added to a soyfree diet, exert estrogenic effects varied with the type of phytoestrogen and the parameter being tested. The genistein diet significantly increased uterine and ovarian weights of ArKO compared to wildtype mice, whilst both the soy, and to a larger extent the genistein diet, improved ovarian morphology compared to the soyfree diet. Transformation to morphological Sertoli cells in ArKO mice was decreased by both phytoestrogen diets, whilst the gene expression of Sertoli cell markers was not affected. The soy diet increased both LH and FSH in both genotypes compared to animals on the soyfree diet. The genistein diet reduced FSH levels in ArKO mice, correlating with increased ovarian inhibin subunit expression. In conclusion, phytoestrogens are estrogenic in ArKO mice. Specifically, they can affect serum gonadotropin levels, and offset the development of Sertoli cells and hemorrhagic cysts within the ovaries, depending on the type of dietary phytoestrogen. Further studies are required to determine the effective doses and treatment regimes for phytoestrogens as endocrine modulators. Supported by NH&MRC Reg Key#198705.

Influence of Prenatal Diethylstilbestrol (DES) and dietary phytoestrogens on sperm function and reproductive organ development in male mice

Objective: The influence of exogenous estrogens on male reproductive parameters remains controversial. Prenatal estrogen exposure may influence male organ development and dietary phytoestrogens have been shown to exert physiologic estrogen activity, with the possible consequence of endocrine disruption. We sought to determine the effects of both in utero exogenous estrogen exposure and dietary phytoestrogen intake on male reproductive organ development and sperm physiology in mice.Design: Experimental animal study.Materials and Methods: In utero exposure of males was performed on pregnant mice fed corn oil with no DES (control), 0.1μg/kg/day DES (low-dose), and 50μg/kg/day DES (high-dose) on gestation days 11–17. Subsequent male pups (n=36) were then fed Purina 5001 (Diet A, 491mg/g diet phytoestrogens) or Purina 5002 (Diet B, 159 mg/g diet phytoestrogens) until sacrifice on postnatal day 90. Testis and epididymal blotted weights were obtained prior to sperm isolation from the cauda epididymis by swim-out after mincing. Morphology, sperm capacitation and acrosome reaction (AR) was evaluated. Cumulus masses from gonadotropin hyperstimulated females were inseminated with sperm at a concentration of 1 million motile sperm per ml for in vitro fertilization (IVF). Percent fertilization, defined as development to the 2-cell stage, and percent embryo development to blastocyst was recorded for each male. Outcome means were analyzed with ANOVA, as well as 2-way ANOVA to detect interactive effects, with p<0.05 considered significant.Results: In utero high-dose DES resulted in decreased testis and epididymal weight, but was not statistically significant unless combined testis/epididymal weight was analyzed (p=0.023). No significant DES effect was seen on sperm morphology, sperm capacitation or acrosome reaction (all p0.05). Fertilization (p=0.477) and embryo development (p=0.410) with IVF was also not adversely affected by in utero DES exposure. No diet effect was seen on epididymal or testis weights or sperm morphology (all p0.05). A decrease in spontaneous capacitation (p<0.001) and AR (p=0.012) was found in the higher phytoestrogen diet. Higher dietary phytoestrogen content also resulted in increased fertilization rates (p=0.014) but lower development to blastocyst (p=0.007). Two-way ANOVA analysis showed no interaction between DES exposure and dietary phytoestrogen content among measured outcomes.Conclusion: In utero high-dose DES exposure decreased combined epididymal/testis weight but had no influence on sperm function or in vitro fertilizing ability. Higher dietary phytoestrogen intake resulted in desirable differences in sperm capacitation and acrosome reaction, as well as improved rates of fertilization with IVF. No interaction between these two exposures existed. Objective: The influence of exogenous estrogens on male reproductive parameters remains controversial. Prenatal estrogen exposure may influence male organ development and dietary phytoestrogens have been shown to exert physiologic estrogen activity, with the possible consequence of endocrine disruption. We sought to determine the effects of both in utero exogenous estrogen exposure and dietary phytoestrogen intake on male reproductive organ development and sperm physiology in mice. Design: Experimental animal study. Materials and Methods: In utero exposure of males was performed on pregnant mice fed corn oil with no DES (control), 0.1μg/kg/day DES (low-dose), and 50μg/kg/day DES (high-dose) on gestation days 11–17. Subsequent male pups (n=36) were then fed Purina 5001 (Diet A, 491mg/g diet phytoestrogens) or Purina 5002 (Diet B, 159 mg/g diet phytoestrogens) until sacrifice on postnatal day 90. Testis and epididymal blotted weights were obtained prior to sperm isolation from the cauda epididymis by swim-out after mincing. Morphology, sperm capacitation and acrosome reaction (AR) was evaluated. Cumulus masses from gonadotropin hyperstimulated females were inseminated with sperm at a concentration of 1 million motile sperm per ml for in vitro fertilization (IVF). Percent fertilization, defined as development to the 2-cell stage, and percent embryo development to blastocyst was recorded for each male. Outcome means were analyzed with ANOVA, as well as 2-way ANOVA to detect interactive effects, with p<0.05 considered significant. Results: In utero high-dose DES resulted in decreased testis and epididymal weight, but was not statistically significant unless combined testis/epididymal weight was analyzed (p=0.023). No significant DES effect was seen on sperm morphology, sperm capacitation or acrosome reaction (all p0.05). Fertilization (p=0.477) and embryo development (p=0.410) with IVF was also not adversely affected by in utero DES exposure. No diet effect was seen on epididymal or testis weights or sperm morphology (all p0.05). A decrease in spontaneous capacitation (p<0.001) and AR (p=0.012) was found in the higher phytoestrogen diet. Higher dietary phytoestrogen content also resulted in increased fertilization rates (p=0.014) but lower development to blastocyst (p=0.007). Two-way ANOVA analysis showed no interaction between DES exposure and dietary phytoestrogen content among measured outcomes. Conclusion: In utero high-dose DES exposure decreased combined epididymal/testis weight but had no influence on sperm function or in vitro fertilizing ability. Higher dietary phytoestrogen intake resulted in desirable differences in sperm capacitation and acrosome reaction, as well as improved rates of fertilization with IVF. No interaction between these two exposures existed.

Stress (hypothalamic–pituitary–adrenal axis) and pain response in male rats exposed lifelong to high vs. low phytoestrogen diets

Estrogens exhibit complex but beneficial effects on brain structure, function and behavior. Soy-derived dietary phytoestrogens protect against hormone-dependent and age-related diseases, due to their estrogen-like hormonal actions. However, the effects of phytoestrogens on brain and behavior are relatively unknown. This study examined the influence of exposing male Long–Evans rats (lifelong) to either a phytoestrogen-rich (Phyto-600) or a phytoestrogen-free (Phyto-free) diet on body weights, behavioral pain thresholds, the hypothalamic–pituitary–adrenal (HPA) hormonal stress response, hippocampal glucocorticoid receptor and brain neural cell adhesion molecules (NCAM) and synaptophysin levels using standard behavioral and biochemical techniques. Body weights were significantly decreased in Phyto-600 fed animals compared to Phyto-free values. There were no significant changes in behavioral pain thresholds, circulating corticosterone concentrations (after acute immobilization stress) or NCAM and synaptophysin levels in various brain regions by the diet treatments. However, Phyto-600 fed males displayed significantly higher plasma adrenocorticotrophin (ACTH) (post-stress) and hippocampal glucocorticoid receptor levels vs. Phyto-free values. These data suggest that (1) body weights are significantly reduced by soy-derived phytoestrogens, (2) behavioral pain thresholds (via heat stimuli) are not influenced by dietary phytoestrogens, but (3) these estrogenic molecules in the hippocampus enhance glucocorticoid receptor abundance and alter the negative feedback of stress hormones towards a female-like pattern of higher ACTH release after activation of the HPA stress axis. This study is the first to show that lifelong consumption of dietary phytoestrogens alters the HPA stress response in male rats.

14. Effects of a high maternal phytoestrogen diet on the reproductive development of male offspring

14. Effects of a high maternal phytoestrogen diet on the reproductive development of male offspring

Neurobehavioral effects of dietary soy phytoestrogens

Phytoestrogens, plant-derived nonsteroidal estrogens found in high abundance in most soy food products, have been studied for their potential beneficial effects against hormone-dependent cancers and age-related diseases. However, little is known about the influence of phytoestrogens on the brain or behavior. This brief review describes mainly our own studies in rodents that have examined the influence of dietary soy isoflavones on certain aspects of brain structure, learning, memory and anxiety along with the brain androgen-metabolizing enzyme, aromatase. These studies used a commercially available diet rich in phytoestrogens (Phyto-rich) vs. a custom diet relatively free of phytoestrogens (Phyto-free). The phytoestrogen content of each diet was determined by high-performance liquid chromatography analysis, circulating plasma phytoestrogen levels were quantified by gas chromatography mass spectroscopy and concentrations of phytoestrogens in specific brain regions were measured by time-resolved fluoroimmunoassay (TR-FIA). Our studies showed that brain aromatase levels were not significantly altered by phytoestrogen diet treatments in perinatal, maternal or adult rats. However, volumes of the sexually dimorphic nucleus of the preoptic area (SDN-POA) were significantly affected by the Phyto-free diet treatment in male rats during adulthood, where SDN-POA volumes were smaller compared to Phyto-rich male values. Additionally, the Phyto-rich diet fed to adult male and female rats produced anxiolytic effects as assessed in the elevated plus maze vs. Phyto-free fed animals. Finally, when learning and memory parameters were examined in a radial arm maze testing visual–spatial memory (VSM), the diet treatments significantly changed the typical sexually dimorphic pattern of VSM. Specifically, adult Phyto-rich fed females outperformed Phyto-free fed females, while in males on the same diets, the opposite pattern of maze performance was observed. When female vs. male performance was compared, Phyto-rich females executed the VSM task in a manner similar to that of Phyto-free fed males, while Phyto-free fed female's VSM was comparable to Phyto-rich males. These results indicate that consumption of dietary phytoestrogens resulting in very high plasma isoflavone levels (in many cases over a relatively short interval of consumption in adulthood) can significantly alter sexually dimorphic brain regions, anxiety, learning and memory. The findings of these studies identify the biological actions of phytoestrogens, specifically isoflavones and their metabolites, found in animal soy-containing diets on brain and behavior and implicate the importance of phytoestrogens given the recognized significance of estrogens in brain and neural disorders, such as Alzheimer's disease, especially in women.

Indigestion of Identities

Indigestion of Identities

Brain aromatase and 5alpha-reductase, regulatory behaviors and testosterone levels in adult rats on phytoestrogen diets.

The purpose of this study was to examine the short-term effects of phytoestrogens in the diet on regulatory behaviors (food/water intake and locomotor activity), prostate weight, testosterone levels, and brain androgen metabolizing enzyme activity levels in adult male rats. Sprague-Dawley rats were fed phytoestrogen-containing versus phytoestrogen-free diets for 29 days. Standard methods were used to measure open field behavior, reproductive, hormonal parameters, and enzymatic activity levels. The phytoestrogen diet contained approximately 200 microg/g of isoflavones whereas in the phytoestrogen-free diet, no phytoestrogens were detected by HPLC analysis. There were no significant differences in any of the regulatory behaviors (food/water intake or locomotor activity), prostate weight, or testosterone levels between the treatment groups. Furthermore, there was no significant influence of phytoestrogens on brain aromatase activity levels, in either the medial basal hypothalamic-preoptic area (MBH-POA) or amygdala brain tissue sites examined. However, significant alterations in MBH-POA and amygdala 5alpha-reductase activities were detected in animals receiving the phytoestrogen-containing versus the phytoestrogen-free diets.

Brain Aromatase and 5 -Reductase, Regulatory Behaviors and Testosterone Levels in Adult Rats on Phytoestrogen Diets

Brain Aromatase and 5 -Reductase, Regulatory Behaviors and Testosterone Levels in Adult Rats on Phytoestrogen Diets

Effects of dietary phytoestrogens in postmenopausal women

The aim of this study was to test the hypothesis that increased dietary intake of phytoestrogens reduces the health impact of the menopause. To test this hypothesis, a double-blind, randomized, entry-exit, cross-over study was conducted to assess the effects of three dietary manipulations - soy and linseed diets (high in phytoestrogens) and a wheat diet (low in phytoestrogens). Postmenopausal women were recruited and randomly assigned to one of the three dietary regimens. Urinary phytoestrogen concentrations, hot flush rate, vaginal smears, bone mineral density and bone mineral content were assessed for two 12-week periods. Comparative analysis showed no significant differences, but, when analyzed separately, groups consuming high phytoestrogen diets had between 10 and 30 times higher urinary excretion of phytoestrogens compared to those consuming the low phytoestrogen diet (p<0.01). Study participants consuming soy, linseed and wheat diets had a 22% (not significant, n.s.), 41% (p < 0.009) and 51% [p < 0.001) reduction in hot flush rate; a 103% (p < 0.04), 5.5% (n.s.) and 11% (n.s.) increase in vaginal cytology maturation index; and a 5.2% (p < 0.04), 5.2% (n.s.) and 3.8% (n.s.) increase in bone mineral content, respectively. No changes were detected in bone mineral density. The differential effects of high phytoestrogen dietary manipulations on outcomes may represent tissue-specific responses to isoflavones and lignans contained in soy and linseed, respectively. Whilst health outcome measures were not significantly different between groups, the data obtained from separate analysis suggest that phytoestrogens in soy and linseed may be of use in ameliorating some of the symptoms of menopause. Furthermore, the significant decrease in hot flush rate in the wheat group cannot be attributable to phytoestrogens measured in this study. Due to subject variability, larger studies are still needed to evaluate population benefit.

Phytoestrogen influences on the development of behavior and gonadotropin function.

The effect of phytoestrogens on the sexual differentiation of gonadotropin function was examined by neonatal exposure of pups through milk of rat dams fed a coumestrol (100 micrograms/g), control, or chow diet during the "critical period" of the first 10 postnatal days or throughout the 21 days of lactation. In females, exposure to coumestrol throughout the period of lactation produced growth suppression and an acyclic condition in early adulthood resembling the premature anovulatory syndrome. When the period of treatment was restricted to the first 10 postnatal days, however, no effects on vaginal cyclicity were seen. The 10-day exposure period produced more marked effects in males, resulting in transitory reductions in body weight in weanling males and reductions in mount and ejaculation frequency and a prolongation of the latencies to mount and ejaculate. Testicular weights and plasma testosterone levels did not differ among treatment groups, suggesting that the deficits in male sexual behavior were not due to deficits in adult gonadal function. Few effects of chow treatment were observed. However, significant differences from controls were apparent for weight at vaginal opening in females, and mount rate for chow-treated males was intermediate between that of controls and that of the coumestrol-treated group. These data provide evidence that lactational exposure to phytoestrogen diets can alter neuroendocrine development in both female and male rats.

A phytoestrogen diet induces the premature anovulatory syndrome in lactationally exposed female rats.

The effects of a phytoestrogen diet on sexual differentiation were examined in lactationally exposed rat pups. Rat dams were provided a semipurified diet containing the isoflavonoid coumestrol at a concentration (0.01%) previously found to be uterotrophic. Coumestrol treatment did not significantly alter the time of vaginal opening, although vaginal opening did occur at a lighter body weight. By 132 days of age, 83% of coumestrol-treated females exhibited the cornified smears of a persistent estrous state. By contrast, 91% of control animals were cycling regularly at 132 days of age. Estradiol stimulation failed to elicit an LH elevation in the coumestrol-treated animals, suggesting the possibility of neuroendocrine impairments. These findings indicate that the female offspring of mothers fed a low-level phytoestrogen diet during lactation manifest early and nearly universal disruption of cyclicity of the persistent-estrus type.

Effects of a normal, human-concentration, phytoestrogen diet on rat uterine growth.

The estrogenic action of the prototype natural phytoestrogen coumestrol was examined in rats in in vitro and in vivo tests. To establish the binding specificity of coumestrol and its relation to biological activities, saturation analyses and uterine weight assays were performed. These assays indicated that coumestrol competitively inhibited binding to the estrogen receptor and induced increases in uterine weight in keeping with its estrogen receptor affinity constant. Most importantly, coumestrol was uterotrophic when incorporated in a semipurified diet at natural dietary concentrations. Significant increases occurred in both uterine wet weight and dry weight, indicating that coumestrol produces true uterine growth. Effects appeared to be cumulative, raising questions of time-related interactions with other estrogen-sensitive mechanisms and clearance of isoflavonoids. Coumestrol induced uterine growth over a 90-hour period at dietary concentrations of 0.01 to 0.1%. Lower doses not active over this period were active when provided over a longer period of time: a 0.005% concentration was not active over a 90-hour period, but was active when provided over a 180-hour period. Coumestrol-induced uterine growth was accompanied by the induction of cytosolic progestin receptors and increases in nuclear estrogen binding. Scatchard analyses verified that these changes were due to changes in receptor number. These studies show that the naturally occurring phytoestrogens have dramatic estrogenic effects at natural dietary levels. These actions may be expressed via traditional receptor-mediated actions and therefore may have the same implications for development, health, and disease as do the steroidal estrogens produced by the body. Because rats have no sex hormone-binding globulin, further studies must be conducted in humans. However, these findings suggest that the natural dietary phytoestrogen coumestrol is a potent estrogen that must be considered in calculating the total estrogenic load to which humans are exposed during normal life.

Effects of a phytoestrogen diet on estrogen-dependent reproductive processes in immature female rats

The study reported here examined the effects of a phytoestrogen diet on progestin receptor induction, vaginal opening, and the onset and maintenance of vaginal cycles in developing female rats. A natural dietary concentration (0.01%) of the isoflavonoidcoumestrol was incorporated into the AIN semipurified diet and fed from 21 to 24 days (acute treatment) or from 22 to 60 days (chronic treatment). Progestin receptor induction was observed in the uterus, pituitary, and hypothalamus-preoptic area following acute treatment. Responses were more marked in the uterus and pituitary than in the hypothalamus-preoptic area. Vaginal opening was accelerated by 4 days during chronic coumestrol treatment and occurred at a lighter body weight. Vaginal cycles began on vaginal opening and did not differ in regularity from those of control animals. However, irregular cycles were observed in coumestrol-treated animals at 116 to 131 days, suggesting that chronic coumestrol treatment may have induced some permanent changes in reproductive function. These findings demonstrate that plant estrogens, at natural dietary levels, produce significant, agonistic actions in several estrogen-dependent tissues and processes.