Neurobehavioral effects of dietary soy phytoestrogens

Daidzein, but not genistein, has anxiolytic-liked effect on intact male Wistar rats

The phytoestrogens daidzein and genistein are ubiquitous in human food. This study aimed to elucidate their anxiety-liked effects, their effects on the reproductive organs, and the molecular mechanism behind any anxiety-liked effects in intact adult male Wistar rats. These phytoestrogens are of interest due to their posited health benefits, particularly for female, but with some effect on males as well. This study comprised two experiments: (1) Male Wistar rats received either a vehicle, daidzein, or genistein (0.25, 0.50, or 1.00 mg/kg) by subcutaneously injection for four weeks. They were then tested for anxiety-liked behaviors. Then, the brain monoamines in anxiolytic rats were determined; (2) The modulation of gamma aminobutyric acid receptors by phytoestrogens was further analyzed by administration of diazepam to phytoestrogen-treated rats before behavioral tests. In the first experiment, the biological parameters measured, including body weight, daily food intake and reproductive organ weights were unaffected by either genistein or daidzein. However, anxiolytic-like effect was observed in the low-dose daidzein (0.25 mg/kg) group. Higher doses of daidzein or genistein of all doses had no effect. Further, the low-dose daidzein did not alter brain monoamine levels. In the second experiment, the anxiolytic-like behavior of daidzein-treated rats receiving diazepam did not differ from that of the rats treated with just diazepam or just daidzein. In conclusion, 4-week exposure to daidzein or genistein had no negative effects on the reproductive organs, body weight, food intake, anxiogenic-like behavior, or monoaminergic and diazepam-modulated GABAergic neurotransmissions of intact male rats. However, beneficial anxiolytic-like effects were apparent after low-dose treatment with daidzein.

Daidzin improves neurobehavioral outcome in rat model of traumatic brain injury

Traumatic brain injury (TBI) is associated with the etiology of multiple neurological disorders, including neurodegeneration, leading to various cognitive deficits. Daidzin (obtained from kudzu root and soybean leaves) is known for its neuroprotective effects through multiple mechanisms. This study aimed to investigate the pharmacological effects of Daidzin on sensory, and biochemical parameters, cognitive functions, anxiety, and depressive-like behaviors in the TBI rat model. Rats were divided into four groups (Control, TBI, TBI + Ibuprofen (30 mg/kg), and TBI + Daidzin (5 mg/kg)). Rats were subjected to TBI by dropping a 200 g rod from a height of 26 cm, resulting in an impact force of 0.51 J on the exposed crania. Ibuprofen (30 mg/kg) was used as a positive control reference/standard drug and Daidzin (5 mg/kg) as the test drug. Neurological severity score (NSS) assessment was done to determine the intactness of sensory and motor responses. Brain tissue edema and acetylcholine levels were determined in the cortex and hippocampus. Cognitive functions such as hippocampus-dependent memory, novel object recognition, exploration, depressive and anxiety-like behaviors were measured. Treatment with Daidzin improved NSS, reduced hippocampal and cortical edema, and improved levels of acetylcholine in TBI-induced rats. Furthermore, Daidzin treatment improved hippocampus-dependent memory, exploration behavior, and novel object recognition while reducing depressive and anxiety-like behavior. Our study revealed that Daidzin has a therapeutic potential comparable to Ibuprofen and can offer neuroprotection and enhanced cognitive and behavioral outcomes in rats after TBI.

A Review of the Effects of Some Extrinsic Factors on Mice Used in Research

Animals have been used in research for over 2,000 y. From very crude experiments conducted by ancient scholars, animal research, as a science, was refined over hundreds of years to what we know it as today. However, the housing conditions of animals used for research did not improve significantly until less than 100 years ago when guidelines for housing research animals were first published. In addition, it was not until relatively recently that some extrinsic factors were recognized as a research variable, even when animals were housed under recommended guidelines. For example, temperature, humidity, light, noise, vibration, diet, water, caging, bedding, etc., can all potentially affect research using mice, contributing the inability of others to reproduce published findings. Consequently, these external factors should be carefully considered in the design, planning, and execution of animal experiments. In addition, as recommended by others, the housing and husbandry conditions of the animals should be described in detail in publications resulting from animal research to improve study reproducibility. Here, we briefly review some common, and less common, external factors that affect research in one of the most popular animal models, the mouse.

Isoflavones Mediate Dendritogenesis Mainly through Estrogen Receptor α

The nuclear estrogen receptor (ER) and G-protein-coupled ER (GPER1) play a crucial role during brain development and are involved in dendrite and spine growth as well as synapse formation. Soybean isoflavones, such as genistein, daidzein, and S-equol, a daidzein metabolite, exert their action through ER and GPER1. However, the mechanisms of action of isoflavones on brain development, particularly during dendritogenesis and neuritogenesis, have not yet been extensively studied. We evaluated the effects of isoflavones using mouse primary cerebellar culture, astrocyte-enriched culture, Neuro-2A clonal cells, and co-culture with neurons and astrocytes. Soybean isoflavone-augmented estradiol mediated dendrite arborization in Purkinje cells. Such augmentation was suppressed by co-exposure with ICI 182,780, an antagonist for ERs, or G15, a selective GPER1 antagonist. The knockdown of nuclear ERs or GPER1 also significantly reduced the arborization of dendrites. Particularly, the knockdown of ERα showed the greatest effect. To further examine the specific molecular mechanism, we used Neuro-2A clonal cells. Isoflavones also induced neurite outgrowth of Neuro-2A cells. The knockdown of ERα most strongly reduced isoflavone-induced neurite outgrowth compared with ERβ or GPER1 knockdown. The knockdown of ERα also reduced the mRNA levels of ER-responsive genes (i.e., Bdnf, Camk2b, Rbfox3, Tubb3, Syn1, Dlg4, and Syp). Furthermore, isoflavones increased ERα levels, but not ERβ or GPER1 levels, in Neuro-2A cells. The co-culture study of Neuro-2A cells and astrocytes also showed an increase in isoflavone-induced neurite growth, and co-exposure with ICI 182,780 or G15 significantly reduced the effects. In addition, isoflavones increased astrocyte proliferation via ER and GPER1. These results indicate that ERα plays an essential role in isoflavone-induced neuritogenesis. However, GPER1 signaling is also necessary for astrocyte proliferation and astrocyte-neuron communication, which may lead to isoflavone-induced neuritogenesis.

Roles of genistein in learning and memory during aging and neurological disorders

Genistein (GEN) is a non-steroidal phytoestrogen that belongs to the isoflavone class. It is abundantly found in soy. Soy and its products are used as food components in many countries including India. The present review is focused to address roles of GEN in brain functions in the context of learning and memory as a function of aging and neurological disorders. Memory decline is one of the most disabling features observed during normal aging and age-associated neurodegenerative disorders namely Alzheimer's disease (AD) and Parkinson's disease (PD), etc. Anatomical, physiological, biochemical and molecular changes in the brain with advancement of age and pathological conditions lead to decline of cognitive functions. GEN is chemically comparable to estradiol and binds to estrogen receptors (ERs). GEN acts through ERs and mimics estrogen action. After binding to ERs, GEN regulates a plethora of brain functions including learning and memory; however detailed study still remains elusive. Due to the neuroprotective, anti-oxidative and anti-inflammatory properties, GEN is used to restore or improve memory functions in different animal models and humans. The present review may be helpful to understand roles of GEN in learning and memory during aging and neurological disorders, its direction of research and therapeutic perspectives.

Impact of feeding habits on the development of language-specific processing of phonemes in brain: An event-related potentials study

Introduction

Infancy is a stage characterized by multiple brain and cognitive changes. In a short time, infants must consolidate a new brain network and develop two important properties for speech comprehension: phonemic normalization and categorical perception. Recent studies have described diet as an essential factor in normal language development, reporting that breastfed infants show an earlier brain maturity and thus a faster cognitive development. Few studies have described a long-term effect of diet on phonological perception.

Methods

To explore that effect, we compared the event-related potentials (ERPs) collected during an oddball paradigm (frequent /pa/80%, deviant/ba/20%) of infants fed with breast milk (BF), cow-milk-based formula (MF), and soy-based formula (SF), which were assessed at 3, 6, 9, 12, and 24 months of age [Mean across all age groups: 127 BF infants, Mean (M) 39.6 gestation weeks; 121 MF infants, M = 39.16 gestation weeks; 116 SF infants, M = 39.16 gestation weeks].

Results

Behavioral differences between dietary groups in acoustic comprehension were observed at 24-months of age. The BF group displayed greater scores than the MF and SF groups. In phonological discrimination task, the ERPs analyses showed that SF group had an electrophysiological pattern associated with difficulties in phonological-stimulus awareness [mismatch negativity (MMN)-2 latency in frontal left regions of interest (ROI) and longer MMN-2 latency in temporal right ROI] and less brain maturity than BF and MF groups. The SF group displayed more right-lateralized brain recruitment in phonological processing at 12-months old.

Discussion

We conclude that using soy-based formula in a prolonged and frequent manner might trigger a language development different from that observed in the BF or MF groups. The soy-based formula's composition might affect frontal left-brain area development, which is a nodal brain region in phonological-stimuli awareness.

A comprehensive approach to modeling maternal immune activation in rodents

Prenatal brain development is a highly orchestrated process, making it a very vulnerable window to perturbations. Maternal stress and subsequent inflammation during pregnancy leads to a state referred to as, maternal immune activation (MIA). If persistent, MIA can pose as a significant risk factor for the manifestation of neurodevelopmental disorders (NDDs) such as autism spectrum disorder and schizophrenia. To further elucidate this association between MIA and NDD risk, rodent models have been used extensively across laboratories for many years. However, there are few uniform approaches for rodent MIA models which make not only comparisons between studies difficult, but some established approaches come with limitations that can affect experimental outcomes. Here, we provide researchers with a comprehensive review of common experimental variables and potential limitations that should be considered when designing an MIA study based in a rodent model. Experimental variables discussed include: innate immune stimulation using poly I:C and LPS, environmental gestational stress paradigms, rodent diet composition and sterilization, rodent strain, neonatal handling, and the inclusion of sex-specific MIA offspring analyses. We discuss how some aspects of these variables have potential to make a profound impact on MIA data interpretation and reproducibility.

Natural drugs targeting inflammation pathways can be used to treat atherosclerosis

Atherosclerosis (AS) is the chronic gradual degradation of arteries in combination with inflammation. Currently, the main research focus has been on interactions between inflammatory cells, inflammatory mediators, and immune mechanisms, while some studies have reported natural drugs were exerting a critical role against AS, whereas the usage of natural drugs was always limited by various factors such as poor penetration across biological barriers, low bioavailability, and unclear mechanisms. Herein, we reviewed the potential targets for inflammation against AS, discussed the underlying mechanisms of natural drugs for AS, particularly highlighted the dilemma of current research, and finally, offered perspectives in this field.

Effect of rosuvastatin on spatial learning, memory, and anxiety-like behaviour in ovariectomized rats

The effect of rosuvastatin (Ros) on cognitive function and anxiety-like behaviour in ovariectomized rats were evaluated. Eighteen female Wistar rats (218-310 g, 6-8 months old) were allocated into sham (n = 6), ovariectomy (Ovx, n = 6) or Ovx + Ros (up to eighth week n = 6, then n = 4) groups. Ros was administered at 20 mg/kg/day by oral gavage for 12 weeks. Behavioural tests were performed at 4, 8 and 12 weeks following Ovx. At 12 weeks, Ovx group had significantly longer escape latency than the sham group at the first day of the four-day training period of the Morris Water Maze test (p < .01). In the Elevated Plus Maze test, Ovx group spent significantly more time in the closed arms than the sham group (p < .01), and this anxiety-like behavioural effect of Ovx was prevented by 12-weeks Ros treatment (p < .05). In conclusion, Ros prevents memory deficit and anxiety-like behaviour in the ovariectomized rats, a model for human surgical menopause. Impact StatementWhat is already known on this subject? Reduced levels of oestrogen in surgical postmenopausal period has been linked to an increased risk of cognitive dysfunction. Although statins have been shown to improve cognitive function in experimental and clinical studies, there are limited studies evaluating the effect of statins on the cognitive decline and anxiety-like behaviour associated with surgical menopause.What do the results of this study add? Rosuvastatin, a long-acting statin, prevents learning and memory deficit and anxiety-like behaviour in the ovariectomized rat model.What are the implications of these findings for future clinical practice and/or future clinical research? These findings will form the basis for further experimental and clinical research on the effects of statins on cognitive functions and anxiety-like behaviour in the surgical menopause.

Reproductive disruption in adult female and male rats prenatally exposed to mesquite pod extract or daidzein

Phytoestrogens are considered to be endocrine disruptors, since they can alter the endocrine system, thus disturbing many reproductive events. The intake of diets containing a high content of phytoestrogens has increased worldwide in human populations and in domestic animals. Phytoestrogens in maternal blood can pass through the placenta to the fetus in high amounts and can have long-term organizational effects. Mesquite (Prosopis sp) is a leguminous plant widely used to feed several livestock species, and is also used in the human diet. In this study we assessed the effects of exposure to mesquite pod extract during the periconception and pregnancy periods on the reproduction of male and female descendants. The females of three experimental groups received one of the following treatments: 1) vehicle injection; 2) mesquite pod extract or 3) the isoflavone daidzein during the periconception and pregnancy periods. Estrous cyclicity, sexual behavior and hormones, as well as uterine and vaginal epithelia were evaluated in the female descendants. In the males, sexual behavior and hormones, apoptosis in testicular cells and sperm quality were evaluated. In females the following was observed: alterations in estrous cycles, decreased sexual behavior, estradiol and progesterone levels, increased uterine and vaginal epithelia. In males, we observed a decrease in sexual behavior, testosterone and sperm quality, and apoptosis increased in testicular cells. All these effects were similar to those caused by daidzein. These results indicate that prenatal exposure to mesquite pod extract or daidzein, administered to females before and during pregnancy, can disrupt normal organizational-activational programming of reproductive physiology in female and male descendants.

Associations between isoflavone exposure and reproductive damage in adult males: evidence from human and model system studies

It's controversial whether exposure to isoflavones, constituents of certain plants such as soy bean, exerts male reproductive toxicity. This study was designed to investigate whether isoflavone exposure during adulthood could have deleterious impacts on male reproductive health by the cross-sectional study, animal experiments, and in vitro tests. In the cross-sectional study, we observed that urinary isoflavones were not significantly associated with semen quality including sperm concentrations, sperm count, progressive motility, and total motility, respectively (All P-value for trend>0.05). However, negative associations were found between plasma testosterone and urinary Σisoflavones, genistein, glycitein, and dihydrodaidzein (all P-value for trend <0.05). In the animal experiments, serum and intratesticular testosterone levels were decreased in mice exposed to several dosages of genistein. Genistein administration caused up-regulation of estrogen receptor alpha (ERα) and down-regulation of cytochrome P45017A1 (CYP17A1) protein levels in testes of mice. However, genistein treatment during adulthood did not induce appreciable structural damages of reproductive system in mice. In vitro tests, we observed that genistein of different dosages (0.01, 2.5, 10 μM) caused a concentration dependent inhibition of testosterone production by TM3 Leydig cells (half-maximal inhibitory concentration = 3.796 nM, P < 0.05). Elevated protein expression of ERα and decreased mRNA/protein level of CYP17A1 were also observed in genistein-treated cells. Protein level of CYP17A1 and testosterone concentration were significantly restored in the ERα siRNA-transfected cells, compared to cells that treated with genistein alone (P < 0.05). The results demonstrate that exposure to isoflavones during adulthood may be associated with alterations of reproductive hormones. Particularly for genistein, which inhibits testosterone biosynthesis through up-regulation of ERα in Leydig cells of mice, might induce the disruption of testosterone production in human. The present study provides novel perspective into potential targets for male reproductive compromise induced by isoflavone exposure.

Expansion and application of dye tracers for measuring solid food intake and food preference in Drosophila

The Drosophila model is used to investigate the effects of diet on physiology as well as the effects of genetic pathways, neural systems and environment on feeding behavior. We previously showed that Blue 1 works well as a dye tracer to track consumption of agar-based media in Drosophila in a method called Con-Ex. Here, we describe Orange 4 as a novel dye for use in Con-Ex studies that expands the utility of this method. Con-Ex experiments using Orange 4 detect the predicted effects of starvation, mating status, strain, and sex on feeding behavior in flies. Orange 4 is consumed and excreted into vials linearly with time in Con-Ex experiments, the number of replicates required to detect differences between groups when using Orange 4 is comparable to that for Blue 1, and excretion of the dye reflects the volume of consumed dye. In food preference studies using Orange 4 and Blue 1 as a dye pair, flies decreased their intake of food laced with the aversive tastants caffeine and NaCl as determined using Con-Ex or a more recently described modification called EX-Q. Our results indicate that Orange 4 is suitable for Con-Ex experiments, has comparable utility to Blue 1 in Con-Ex studies, and can be paired with Blue 1 to assess food preference via both Con-Ex and EX-Q.

Isoflavones derived from plant raw materials: bioavailability, anti-cancer, anti-aging potentials, and microbiome modulation

Isoflavones are secondary metabolites that represent the most abundant category of plant polyphenols. Dietary soy, kudzu, and red clover contain primarily genistein, daidzein, glycitein, puerarin, formononetin, and biochanin A. The structural similarity of these compounds to β-estradiol has demonstrated protection against age-related and hormone-dependent diseases in both genders. Demonstrative shreds of evidence confirmed the fundamental health benefits of the consumption of these isoflavones. These relevant activities are complex and largely driven by the source, active ingredients, dose, and administration period of the bioactive compounds. However, the preclinical and clinical studies of these compounds are greatly variable, controversial, and still with no consensus due to the non-standardized research protocols. In addition, absorption, distribution, metabolism, and excretion studies, and the safety profile of isoflavones have been far limited. This highlights a major gap in understanding the potentially critical role of these isoflavones as prospective replacement therapy. Our general review exclusively focuses attention on the crucial role of isoflavones derived from these plant materials and critically highlights their bioavailability, possible anticancer, antiaging potentials, and microbiome modulation. Despite their fundamental health benefits, plant isoflavones reveal prospective therapeutic effects that worth further standardized analysis.

Anti-neuroinflammatory effect of daidzein in human hypothalamic GnRH neurons in an in vitro membrane-based model

Phytoestrogens can control high-fat diet-induced hypothalamic inflammation that is associated with severe consequences, including obesity, type 2 diabetes, cardiovascular and neurodegenerative diseases. However, the phytoestrogen anti-neuroinflammatory action is poorly understood. In this study, we explored the neuroprotection mediated by daidzein in hypothalamic neurons by using a membrane-based model of obesity-related neuroinflammation. To test the daidzein therapeutic potential a biohybrid membrane system, consisting of hfHypo GnRH-neurons in culture on PLGA membranes, was set up. It served as reliable in vitro tool capable to recapitulate the in vivo structure and function of GnRH hypothalamic tissue. Our findings highlighted the neuroprotective role of daidzein, being able to counteract the palmitate induced neuroinflammation. Daidzein protected hfHypo GnRH cells by downregulating cell death, proinflammatory processes, oxidative stress, and apoptosis. It also restored the proper cell morphology and functionality through a mechanism which probably involves the activation of ERβ and GPR30 receptors along with the expression of GnRH peptide and KISS1R.

Soy flavonoids prevent cognitive deficits induced by intra-gastrointestinal administration of beta-amyloid

BACKGROUND

In Alzheimer's diseases, beta-amyloid may act as prion-like protein and migrate from the gastrointestinal tract towards the brain. Soy flavonoids have been identified as neuroprotective against cognitive loss in human. Diet with soy flavonoids may be used to slow down the progression of Alzheimer's diseases.

METHODS AND RESULTS

We performed in-vitro tissue culture experiments using myenteric plexus longitudinal muscle layers isolated from the ileum and colon of ICR mice. Beta-amyloid can be taken up into myenteric neurons and induce neuron degeneration, which is protected by flavonoids compounds, including daidzein, genistein, glycitein and luteolin. We also administered oligomeric beta-amyloid (1-42) (total dose: 8 μg) into the gastrointestinal walls of ICR mice and conducted memory tests and gastrointestinal function assessments after 6 and 12 months. Mice treated with beta-amyloid exhibited minor learning deficits in a T-maze memory test at 6 months and significant memory impairment in a novel object recognition task at 12 months. These impairments were prevented by soy flavonoids. Tracking studies performed using fluorescently tagged beta-amyloid found that, beta-amyloid injected at the stomach can aggregate within the layer of myenteric neurons and migrate to the jejunum or via the vagus nerves to the brain after 1 month. Reductions in the gastrointestinal tissue weight and the spontaneous ileal contraction frequency were also observed at 6 and 12 months, respectively.

CONCLUSION

Our findings indicate that beta-amyloid can migrate from the gastrointestinal tract to the brain to induce cognitive impairments. Furthermore, chronic soy flavonoids in drinking water have protective actions.

Gender Differences in Phytoestrogens and the Relationship with Speed of Processing in Older Adults: A Cross-Sectional Analysis of NHANES, 1999-2002

Sex hormone changes in adults are known to play a part in aging, including cognitive aging. Dietary intake of phytoestrogens can mimic estrogenic effects on brain function. Since sex hormones differ between genders, it is important to examine gender differences in the phytoestrogen–cognition association. Therefore, the goal of this study is to examine the relationship between urinary phytoestrogens and speed of processing (SOP) and the variation of the association between genders in older adults. Participants were drawn from the 1999–2002 National Health and Nutrition Examination Survey and included 354 individuals aged 65–85 years old. General linear models (GLMs) were used to test for significant gender differences in the relationship between phytoestrogens and SOP. Results from the GLMs showed significant gender differences in the relationship between genistein and SOP. Higher levels of genistein were associated with better SOP in women. This relationship was reversed in men: higher genistein levels were associated with worse performance. Results indicate that there are distinct gender differences in the relationship between genistein and SOP. These results emphasize the importance of considering gender differences when devising dietary and pharmacologic interventions that target phytoestrogens to improve brain health.

Isoflavones Alter Hypothalamic-Pituitary-Adrenal Axis Response Following Photoperiod Alteration

Photoperiod and diet are factors known to modulate the hypothalamic-pituitary-adrenal (HPA) axis. Specifically, shifts in photoperiod have been previously linked with affective and anxiety disorders. Furthermore, isoflavones have been shown to mediate behavioral outcome in response to the environment of the animal. Here, we investigated the effect of photoperiod alteration on the HPA axis and how the addition of isoflavones might modulate the response to stress. Male C57BL/6J mice were maintained on either a 12:12 or a 16:8 light-dark (LD) cycle for 10 days, and fed a diet of either standard rodent chow or an isoflavone free (IF) chow beginning 3 weeks prior to light alteration. Consistent with previous work, mice in the shorter active period (16:8 LD cycle) showed increased basal corticosterone (CORT) secretion. In the absence of isoflavones, this response was attenuated. Increases in mineralcorticoid (MR) and glucocorticoid (GR) receptor mRNA expression were seen in the pituitary following photoperiod alteration. However, animals fed the standard isoflavone rich chow showed increases in the ratio of MR:GR mRNA in the anterior bed nucleus of the stria terminalis following photoperiod alteration. Decreases in corticotrophin-releasing factor receptor 1 (CRFR1) mRNA expression were seen in animals fed the IF chow in the amygdala, prefrontal cortex and ventral hippocampus. These data suggest that alterations in CORT secretion following photoperiod alteration may be mediated through differences in CRFR1 gene expression or changes in MR:GR mRNA ratios. These findings provide insight into the potential mechanisms by which the HPA axis adapts to photoperiod and diet.

Selected Psychological Aspects of Meat Consumption-A Short Review

Eating meat is deeply entrenched in Western culture. It is often associated with wealth and a highly nutritional diet; and for many people it is also an established habit that is difficult to change. The second half of the 20th century was a period of rapid growth in meat consumption, which resulted in intensified meat production. At the same time, eating meat has recently become subject to criticism for health-related, environmental or humanitarian reasons. This review aims to signal the potential consequences of a change of diet or switching to diets that are rich/poor in certain ingredients on the functioning of the hormonal and nervous system, which translates into changes in mood and behavior. This paper discusses the psychological phenomena which underlie the difficulty of changing one's food preferences and problems encountered while adding new products to the daily diet. Finally, this study summarizes the limitations of modifying eating habits that have resulted from established attitudes and habits.

Multidimensional chemobehavior analysis of flavonoids and neuroactive compounds in zebrafish

The comparative analysis of complex behavioral phenotypes is valuable as a reductionist tool for both drug discovery and defining chemical bioactivity. Flavonoids are a diverse class of chemicals that elicit robust neuroactive and hormonal actions, though bioactivity information is limited for many, particularly for neurobehavioral endpoints. Here, we used a zebrafish larval chemomotor response (LCR) bioassay to comparatively evaluate a suite of 24 flavonoids, and in addition a panel of 30 model neuroactive compounds representing diverse modes of action (e.g. caffeine, chlorpyrifos, methamphetamine, nicotine, picrotoxin). Naïve larval zebrafish were exposed to concentration ranges of each compound at 120 hour post-fertilization (hpf) and locomotor activity measured for 5 h. The model neuroactive compounds were largely behaviorally bioactive (20 of 30) with most effects phenotypic of their known modes of action. Flavonoids rapidly and broadly elicited hyperactive locomotor effects (22 of 24). Multidimensional analyses compared responses over time and identified three distinct bioactive groups of flavonoids based on efficacy and potency. Using GABAergics to modulate hyperactive responses, two flavonoids, (S)-equol and kaempferol were tested for GABA_A receptor antagonism, as well as a known GABA_A receptor antagonist, picrotoxin. Pharmacological intervention with positive allosteric modulators of the GABA_A receptor, alfaxalone and chlormethiazole, ameliorated the hyperactive response to picrotoxin, but not for (S)-equol or kaempferol. Taken together, these studies demonstrate that flavonoids are differentially bioactive and that the chemobehavioral effects likely do not involve a GABA_A receptor mediated mode of action. Overall, the integrative zebrafish platform provides a useful framework for comparatively evaluating high-content chemobehavioral data for sets of structurally- and mechanistically-related flavonoids and neuroactive compounds.

Treatment with soy isoflavones during early adulthood improves metabolism in early postnatally overfed rats

PURPOSE

The incidences of obesity and related diseases have reached epidemic proportions, and new therapeutic approaches are needed. Soy isoflavones have been identified as an important dietary factor for preventing and treating metabolic dysfunction. This study examined the effects of high doses of isoflavone on glucose and fat metabolism in a model of programmed obesity and evaluated its effects on the autonomic nervous system.

METHODS

Litters of Wistar rats were standardized at nine pups per dam in normal litters (NL) or reduced to three pups per dam at the third day of life (P3) in small litters (SL) to induce postnatal overfeeding. Gavage with a soy bean isoflavone mixture (1 g/day) diluted in water was started at P60 and continued for 30 days. The control animals received vehicle gavage. At P90, biometric and metabolic parameters as well as direct autonomic nerve activity were measured.

RESULTS

Increases in glycaemia and insulinaemia observed in SL rats were reduced by isoflavone treatment, which also caused lower glucose-induced insulin secretion by pancreatic islets. Sympathetic activity in the major splanchnic nerve was increased, while vagus nerve activity was reduced by isoflavone treatment. The dyslipidaemia induced by overfeeding in SL rats was restored by isoflavone treatment.

CONCLUSION

The present study shows that treatment with isoflavone reduces adiposity and improves glucose and lipid metabolism. Collectively, these effects may depend on autonomic changes.

Endocrine disruption by dietary phyto-oestrogens: impact on dimorphic sexual systems and behaviours

A wide range of health benefits have been ascribed to soya intake including a lowered risk of osteoporosis, heart disease, breast cancer, and menopausal symptoms. Because it is a hormonally active diet, however, soya can also be endocrine disrupting, suggesting that intake has the potential to cause adverse health effects in certain circumstances, particularly when exposure occurs during development. Consequently, the question of whether or not soya phyto-oestrogens are beneficial or harmful to human health is neither straightforward nor universally applicable to all groups. Possible benefits and risks depend on age, health status, and even the presence or absence of specific gut microflora. As global consumption increases, greater awareness and consideration of the endocrine-disrupting properties of soya by nutrition specialists and other health practitioners is needed. Consumption by infants and small children is of particular concern because their hormone-sensitive organs, including the brain and reproductive system, are still undergoing sexual differentiation and maturation. Thus, their susceptibility to the endocrine-disrupting activities of soya phyto-oestrogens may be especially high. As oestrogen receptor partial agonists with molecular and cellular properties similar to anthropogenic endocrine disruptors such as bisphenol A, the soya phyto-oestrogens provide an interesting model for how attitudes about what is 'synthetic' v. what is 'natural,' shapes understanding and perception of what it means for a compound to be endocrine disrupting and/or potentially harmful. This review describes the endocrine-disrupting properties of soya phyto-oestrogens with a focus on neuroendocrine development and behaviour.

The interaction of dietary isoflavones and estradiol replacement on behavior and brain-derived neurotrophic factor in the ovariectomized rat

Phytoestrogens are plant derived, non-steroidal compounds naturally found in rodent chows that potentially have endocrine-disrupting effects. Isoflavones, the most common phytoestrogens, have a similar structure and molecular weight to 17β-estradiol (E2) and have the ability to bind and activate both isoforms of the estrogen receptor (ER). Most isoflavones have a higher affinity for ERβ, which is involved in sexually dimorphic behavioral regulation. The goal of this study was to examine the interaction of isoflavones and E2 presence in the OVX rat on anxiety- and depressive- like behavior and the related BDNF pathophysiology. E2 administration resulted in anxiogenic behaviors when isoflavones were present in the diet (p<0.05), but anxiolytic behaviors when isoflavones were not present (p<0.05). E2 resulted in antidepressive-like behaviors in animals fed an isoflavone-rich diet (p<0.05), with no effect when isoflavones were removed. Increased hippocampal BDNF expression was observed in animals fed an isoflavone-rich diet after E2 administration (p<0.05). BDNF expression in the amygdala and hypothalamus was increased after E2 treatment in animals fed an isoflavone-rich diet. Overall, these results demonstrate that the presence of dietary isoflavones can differentially regulate the effect of E2 replacement on behavior and BDNF expression.

Low dietary soy isoflavonoids increase hippocampal spine synapse density in ovariectomized rats

High dietary intake of plant estrogens (phytoestrogens) can affect brain structure and function. The effects of phytoestrogen intake within the range of normal animal and human dietary consumption, however, remain uncertain. The aim of the present study was to determine the effects of the isoflavonoids present in a standard low phytoestrogen laboratory rat chow on spine synapse density in the stratum radiatum of area CA1 of the hippocampus. Weanling rats (22days old) were fed either standard chow (Teklad 2018), a nutritionally comparable diet without soy (Teklad 2016) or a custom diet containing Teklad 2016 supplemented with the principal soy isoflavonoids, daidzein and genistein, for 40days. Rats were ovariectomized at 54days of age. Eight days later, spine synapse density on the apical dendrites of hippocampal pyramidal neurons in the stratum radiatum of area CA1 was measured by electron microscopic stereological analysis. Animals maintained on Teklad 2016 exhibited an approximately 60% lower CA1 spine synapse density than animals consuming Teklad 2018. Replacing genistein and daidzein in Teklad 2016 returned synapse density to levels indistinguishable from those in animals on Teklad 2018. These results indicate that the isoflavonoids in a standard laboratory rat diet exert significant effects on spine synapse density in the CA1 region of the hippocampus. Since changes in spine synapse density in this region of the hippocampus have been linked to cognitive performance and mood state, these data suggest that even relatively low daily consumption of soy phytoestrogens may be sufficient to influence hippocampal function.

Endocrine Disruption of Vasopressin Systems and Related Behaviors

Endocrine disrupting chemicals (EDCs) are chemicals that interfere with the organizational or activational effects of hormones. Although the vast majority of the EDC literature focuses on steroid hormone signaling related impacts, growing evidence from a myriad of species reveals that the nonapeptide hormones vasopressin (AVP) and oxytocin (OT) may also be EDC targets. EDCs shown to alter pathways and behaviors coordinated by AVP and/or OT include the plastics component bisphenol A (BPA), the soy phytoestrogen genistein (GEN), and various flame retardants. Many effects are sex specific and likely involve action at nuclear estrogen receptors. Effects include the elimination or reversal of well-characterized sexually dimorphic aspects of the AVP system, including innervation of the lateral septum and other brain regions critical for social and other non-reproductive behaviors. Disruption of magnocellular AVP function has also been reported in rats, suggesting possible effects on hemodynamics and cardiovascular function.

Molecular and Therapeutic Targets of Genistein in Alzheimer's Disease

Alzheimer's disease (AD) is a devastating brain disorder characterized by an increased level of amyloid-beta (Aβ) peptide deposition and neuronal cell death leading to an impairment of learning and thinking skills. The Aβ deposition is a key factor in senile plaques of the AD brain which cause the elevation of intracellular calcium ions and the production of formidable free radicals, both of which greatly contribute to the AD-associated cascade, leading to unstoppable neuronal loss in the hippocampal region of the brain. Natural products are currently considered as an alternative strategy for the discovery of novel multipotent drugs against AD. They include the naturally occurring dietary soy isoflavone genistein which has been recognized to possess several health-promoting effects. Genistein has been mainly focused because of its potential on amelioration of Aβ-induced impairment and its antioxidant capacity to scavenge the free radicals produced in AD. It can also directly interact with the targeted signaling proteins and stabilize their activity to prevent AD. An improved understanding of the direct interactions between genistein and target proteins would contribute to the further development of AD treatment. This review mainly focuses on molecular targets and the therapeutic effects regulated by genistein, which has the ability to directly target the Aβ peptide and to control its activity involved in intracellular signaling pathways, which otherwise would lead to neuronal death in the hippocampal region of the AD brain.

Comparative Developmental Toxicity of Flavonoids Using an Integrative Zebrafish System

Flavonoids are a large, structurally diverse class of bioactive naturally occurring chemicals commonly detected in breast milk, soy based infant formulas, amniotic fluid, and fetal cord blood. The potential for pervasive early life stage exposures raises concerns for perturbation of embryogenesis, though developmental toxicity and bioactivity information is limited for many flavonoids. Therefore, we evaluated a suite of 24 flavonoid and flavonoid-like chemicals using a zebrafish embryo-larval toxicity bioassay-an alternative model for investigating developmental toxicity of environmentally relevant chemicals. Embryos were exposed to 1-50 µM of each chemical from 6 to 120 h postfertilization (hpf), and assessed for 26 adverse developmental endpoints at 24, 72, and 120 hpf. Behavioral changes were evaluated in morphologically normal animals at 24 and 72 hpf, at 120 hpf using a larval photomotor response (LPR) assay. Gene expression was comparatively evaluated for all compounds for effects on biomarker transcripts indicative of AHR (cyp1a) and ER (cyp19a1b, esr1, lhb, vtg) pathway bioactivity. Overall, 15 of 24 flavonoids elicited adverse effects on one or more of the developmental or behavioral endpoints. Hierarchical clustering and principle component analyses compared toxicity profiles and identified 3 distinct groups of bioactive flavonoids. Despite robust induction of multiple estrogen-responsive biomarkers, co-exposure with ER and GPER antagonists did not ameliorate toxicity, suggesting ER-independence and alternative modes of action. Taken together, these studies demonstrate that development is sensitive to perturbation by bioactive flavonoids in zebrafish that are not related to traditional estrogen receptor mode of action pathways. This integrative zebrafish platform provides a useful framework for evaluating flavonoid developmental toxicity and hazard prioritization.

Detecting the QTL-allele system of seed isoflavone content in Chinese soybean landrace population for optimal cross design and gene system exploration

KEY MESSAGE

Utilizing an innovative GWAS in CSLRP, 44 QTL 199 alleles with 72.2 % contribution to SIFC variation were detected and organized into a QTL-allele matrix for cross design and gene annotation. The seed isoflavone content (SIFC) of soybeans is of great importance to health care. The Chinese soybean landrace population (CSLRP) as a genetic reservoir was studied for its whole-genome quantitative trait loci (QTL) system of the SIFC using an innovative restricted two-stage multi-locus genome-wide association study procedure (RTM-GWAS). A sample of 366 landraces was tested under four environments and sequenced using RAD-seq (restriction-site-associated DNA sequencing) technique to obtain 116,769 single nucleotide polymorphisms (SNPs) then organized into 29,119 SNP linkage disequilibrium blocks (SNPLDBs) for GWAS. The detected 44 QTL 199 alleles on 16 chromosomes (explaining 72.2 % of the total phenotypic variation) with the allele effects (92 positive and 107 negative) of the CSLRP were organized into a QTL-allele matrix showing the SIFC population genetic structure. Additional differentiation among eco-regions due to the SIFC in addition to that of genome-wide markers was found. All accessions comprised both positive and negative alleles, implying a great potential for recombination within the population. The optimal crosses were predicted from the matrices, showing transgressive potentials in the CSLRP. From the detected QTL system, 55 candidate genes related to 11 biological processes were χ (2)-tested as an SIFC candidate gene system. The present study explored the genome-wide SIFC QTL/gene system with the innovative RTM-GWAS and found the potentials of the QTL-allele matrix in optimal cross design and population genetic and genomic studies, which may have provided a solution to match the breeding by design strategy at both QTL and gene levels in breeding programs.

Phytoestrogens in Botanical Dietary Supplements: Implications for Cancer

Phytoestrogens are plant constituents that possess either estrogenic or antiestrogenic activity. Although their activities are weak as compared with human endogenous estrogens, the consumption of phytoestrogens may have clinically significant consequences. A number of botanicals, or the compounds contained therein, have been identified as putative estrogenic agents, but consensus in the biomedical community has been hampered by conflicting data from various in vitro and in vivo models of estrogenic activity. Phytoestrogens may serve as chemopreventive agents while at the same time being capable of promoting growth in estrogen receptor positive cancer cell lines. Furthermore, they may exert their estrogenic influence through receptor-dependent and/or receptor-independent mechanisms. These findings have led to speculation that phytoestrogen intake might be ill advised for patients at an increased risk for hormone-dependent cancers, cancer patients, or cancer survivors. This article will attempt to sort out discrepancies between various experimental models and establish whether certain herbs possess estrogenic activity. The review will focus on 5 popular botanical dietary supplements: Trifolium pratense (red clover), Cimicifuga racemosa (black cohosh), Humulus lupulus (hops), Angelica sinensis (dong quai), and Glycyrrhiza glabra (licorice). It will address their mechanisms of action, clinical evidence bases, and implications for use in cancer.

Genistein causes germ cell reduction in the genital ridges of Japanese quail Coturnix japonica embryo

Genistein (GEN), an isoflavonoid phytoestrogen, is one of the potent estrogenic compounds derived from plants that can cause disrupting effects on sex organ development in non-mammalian and mammalian species. The present study revealed effect of genistein on germ cell number in the genital ridges during gonadogenesis. Genistein (16 and 24 μg/g egg) was injected into the egg yolk prior to incubation. Effect of genistein on quail-primordial germ cells (PGCs) number was examined by counting the number of Wisteria floribunda (WFA)-positive cells localized in both left and right genital ridges compared with the control group. Both concentrations of genistein resulted in significant decrease of PGC number compared with the control group. Percentages of the sterility rate of the embryo treated with 16 and 24 μg of genistein/g egg were 19% and 23%, respectively. These results provide evidence that genistein may be a germ cell toxicant causing sterility later in life of adult birds. This is the first report on the effect of genistein on PGC number in the genital ridges of the avian embryo.

Assessment of the Effects of 6 Standard Rodent Diets on Binge-Like and Voluntary Ethanol Consumption in Male C57BL/6J Mice

BACKGROUND

In recent years, much attention has been given to the lack of reproducibility in biomedical research, particularly in preclinical animal studies. This is a problem that also plagues the alcohol research field, particularly in consistent consumption in animal models of alcohol use disorders. One often overlooked factor that could affect reproducibility is the maintenance diet used in preclinical studies.

METHODS

Herein, 2 well-established models of alcohol consumption, the "drinking in the dark" (DID) procedure and the continuous 2-bottle choice (C2BC) paradigm, were employed to determine the effects of diet on ethanol (EtOH) consumption. Male C57BL/6J mice were given 1 of 6 standard rodent chow diets obtained from Purina LabDiet(®) , Inc. (Prolab(®) RMH 3000) or Harlan(®) Laboratories, Inc. (Teklad Diets T.2916, T.2918, T.2920X, T.7912, or T.8940). A separate group of animals were used to test dietary effects on EtOH pharmacokinetics and behavioral measures following intraperitoneal (IP) injections of various doses of EtOH.

RESULTS

Mice eating Harlan diets T.2916 (H2916) and T.2920X (H2920) consumed significantly less EtOH and exhibited lower blood EtOH concentrations (BECs) during DID; however, during C2BC, animals maintained on Harlan T.7912 (H7912) consumed more EtOH and had a higher EtOH preference than the other diet groups. EtOH consumption levels did not stem from changes in alcohol pharmacokinetics, as a separate group of animals administered EtOH IP showed no difference in BECs. However, animals on Harlan diet T.2920X (H2920) were more sensitive to alcohol-induced locomotor activity in an open-field task. No diet-dependent differences were seen in alcohol-induced sedation as measured with loss of righting reflex.

CONCLUSIONS

Although these data do not identify a specific mechanism, together, they clearly show that the maintenance diet impacts EtOH consumption. It is incumbent upon the research community to consider the importance of describing nutritional information in methods, which may help decrease interlaboratory reproducibility issues.

Opioid receptor-dependent sex differences in synaptic plasticity in the hippocampal mossy fiber pathway of the adult rat

The mossy fiber (MF) pathway is critical to hippocampal function and influenced by gonadal hormones. Physiological data are limited, so we asked whether basal transmission and long-term potentiation (LTP) differed in slices of adult male and female rats. The results showed small sex differences in basal transmission but striking sex differences in opioid receptor sensitivity and LTP. When slices were made from females on proestrous morning, when serum levels of 17β-estradiol peak, the nonspecific opioid receptor antagonist naloxone (1 μm) enhanced MF transmission but there was no effect in males, suggesting preferential opioid receptor-dependent inhibition in females when 17β-estradiol levels are elevated. The μ-opioid receptor (MOR) antagonist Cys2,Tyr3,Orn5,Pen7-amide (CTOP; 300 nm) had a similar effect but the δ-opioid receptor (DOR) antagonist naltrindole (NTI; 1 μm) did not, implicating MORs in female MF transmission. The GABAB receptor antagonist saclofen (200 μm) occluded effects of CTOP but the GABAA receptor antagonist bicuculline (10 μm) did not. For LTP, a low-frequency (LF) protocol was used because higher frequencies elicited hyperexcitability in females. Proestrous females exhibited LF-LTP but males did not, suggesting a lower threshold for synaptic plasticity when 17β-estradiol is elevated. NTI blocked LF-LTP in proestrous females, but CTOP did not. Electron microscopy revealed more DOR-labeled spines of pyramidal cells in proestrous females than males. Therefore, we suggest that increased postsynaptic DORs mediate LF-LTP in proestrous females. The results show strong MOR regulation of MF transmission only in females and identify a novel DOR-dependent form of MF LTP specific to proestrus.

Adult emotionality and neural plasticity as a function of adolescent nutrient supplementation in male rats

The present study explored the effects of supplementing male rats with either choline, omega-3 fatty acids, or phytoestrogens, from weaning into early adulthood, on emotionality and hippocampal plasticity. Because of the neuroprotective properties of these nutrients, we hypothesized that they would positively affect both behavior and hippocampal function when compared to non-supplemented control rats. To test this hypothesis, male Sprague Dawley rats were assigned to one of four nutrient conditions after weaning: 1) control (normal rat chow); 2) choline (supplemented in drinking water); 3) omega 3 fatty acids (daily oral supplements); or 4) phytoestrogens (supplemented in chow). After 4weeks on their respective diets, a subset of rats began 3weeks of behavioral testing, while the remaining behaviorally naïve rats were sacrificed after 6weeks on the diets to assess numbers of adult-born hippocampal neurons using the immature neuron marker, doublecortin. The results revealed that choline supplementation affected emotional functioning; compared to rats in other diet conditions, rats in this group were less anxious in an open field and after exposure to predator odor and showed less behavioral despair after forced swimming. Similar behavioral findings were evident following supplementation with omega-3 fatty acids and phytoestrogen supplementation, though not on all tests and not to the same magnitude. Histological findings followed a pattern consistent with the behavioral findings: choline supplementation, followed by omega-3 fatty acid supplementation, but not phytoestrogen supplementation, significantly increased the numbers of new-born hippocampal neurons. Choline and omega-3 fatty acids have similar biological functions-affecting cell membranes, growth factor levels, and epigenetically altering gene transcription. Thus, the present findings suggest that targeting nutrients with these effects may be a viable strategy to combat adult psychopathologies.

Influence of gonadal hormones on the behavioral effects of intermittent hypoxia in mice

Obstructive sleep apnea (OSA) is characterized by repetitive upper airway obstruction resulting in cyclic intermittent hypoxia (IH) during sleep in affected individuals. OSA occurs more frequently in postmenopausal than premenopausal women and the severity of OSA increases after menopause. Gonadal hormones can influence brain and behavior; testosterone and estrogens in particular can enhance spatial learning and memory. We hypothesized that estrogens may protect mice from IH-induced hippocampal morphological and behavioral changes. To test this hypothesis we exposed intact or gonadectomized male and female mice to room air or IH [15 cycles/h, 8 h/day, fraction of inspired oxygen (FiO 2) nadir of 5%] for a total of 30 days. During the final 4 days of IH, mice were tested for anxiety- and depressive-like behaviors. After cessation of IH exposure mice were tested on the Barnes maze and passive avoidance tests to assess learning and memory. Ovariectomy paired with IH treatment, impaired spatial learning and memory compared to all other female groups. Intact male mice receiving IH treatment also had impaired learning and memory compared with intact or castrated male mice exposed to room air. Learning and memory changes were mirrored by changes in basilar dendritic length of the CA1 region of the hippocampus. These data suggest that estrogens provide protection against IH-induced deficits, whereas androgens partially exacerbate IH-induced deficits on learning and memory.

Molecular docking and panicolytic effect of 8-prenylnaringenin in the elevated T-maze

The purpose of this study was to investigate the effects of the chronic administration of a racemic mixture of 8-prenylnaringenin (8-PN) on rats submitted to the elevated T-maze (ETM) model of generalized anxiety and panic disorders. The selective serotonin (SERT) reuptake inhibitor fluoxetine was used as a positive control. Rat locomotion was assessed in a circular arena following each drug treatment. The administration of racemic 8-PN for 21 d in rats increased one-way escape latencies from the ETM open arm, indicating a panicolytic effect. To evaluate the interactions of 8-PN with monoamine transporters, a docking study was performed for both the R and S configurations of 8-PN towards SERT, norepinephrine (NET) and dopamine transporters (DAT). The application of the docking protocol showed that (R)-8-PN provides greater affinity to all transporters than does the S enantiomer. This result suggests that enantiomer (R)-8-PN is the active form in the in vivo test of the racemic mixture.

Effects of genistein on stereological and hormonal characteristics of the pituitary somatotrophs in rats

The hypothalamic-pituitary somatotropic system plays a pivotal role in the regulation of physiological processes and metabolism, which is modulated by gonadal steroids. Considering that genistein belongs to the phytoestrogen family and acts via similar mechanisms to estrogens, the present study was designed to demonstrate whether genistein modulates the morphofunctional characteristic of somatotrophs [growth hormone (GH) cells] in adult rats in comparison with the effects of estradiol. In the study, the orchidectomized adult rats were used as an appropriate model system for testing the effects of this hormone-like substance. Changes in the pituitary somatotrophs were evaluated histologically and stereologically, while GH level was determined biochemically. Using immunolabelling and stereological methods, we showed that orchidectomy (Orx) provoked the decrease of GH cell volume density. After estradiol treatment of Orx rats, the most prominent change concerned the pituitary relative intensity of GH fluorescence and circulating GH level, which were elevated 77 % and 4.7-fold, respectively. Clearly, in contrast to orchidectomy, estradiol treatment enhanced the GH cells activity. Genistein treatment increased pituitary weight and volume, GH cell volume density, the total number of GH cells, and GH blood concentration (1.3-fold) in comparison to the Orx group. Although identical tendencies followed estradiol and genistein administration, the changes observed after genistein treatment were milder compared to estradiol treatment.

Geniposide, the component of the Chinese herbal formula Tongluojiunao, protects amyloid-β peptide (1-42-mediated death of hippocampal neurons via the non-classical estrogen signaling pathway

Tongluojiunao (TLJN) is an herbal medicine consisting of two main components, geniposide and ginsenoside Rg1. TLJN has been shown to protect primary cultured hippocampal neurons. However, its mechanism of action remains unclear. In the present study, primary cultured hippocampal neurons treated with Aβ_1–42 (10 µmol/L) significantly increased the release of lactate dehydrogenase, which was markedly reduced by TLJN (2 µL/mL), specifically by the component geniposide (26 µmol/L), but not ginsenoside Rg1 (2.5 µmol/L). The estrogen receptor inhibitor, ICI182780 (1 µmol/L), did not block TLJN- or geniposide-mediated decrease of lactate dehydrogenase under Aβ_1–42-exposed conditions. However, the phosphatidyl inositol 3-kinase or mitogen-activated protein kinase pathway inhibitor, LY294002 (50 µmol/L) or U0126 (10 µmol/L), respectively blocked the decrease of lactate dehydrogenase mediated by TLJN or geniposide. Therefore, these results suggest that the non-classical estrogen pathway (i.e., phosphatidyl inositol 3-kinase or mitogen-activated protein kinase) is involved in the neuroprotective effect of TLJN, specifically its component, geniposide, against Aβ_1–42-mediated cell death in primary cultured hippocampal neurons.

Endocrine-disrupting chemicals: elucidating our understanding of their role in sex and gender-relevant end points

Endocrine-disrupting chemicals (EDCs) are diverse and pervasive and may have significant consequence for health, including reproductive development and expression of sex-/gender-sensitive parameters. This review chapter discusses what is known about common EDCs and their effects on reproductively relevant end points. It is proposed that one way that EDCs may exert such effects is by altering steroid levels (androgens or 17-estradiol, E₂) and/or intracellular E₂ receptors (ERs) in the hypothalamus and/or hippocampus. Basic research findings that demonstrate developmentally sensitive end points to androgens and E₂ are provided. Furthermore, an approach is suggested to examine differences in EDCs that diverge in their actions at ERs to elucidate their role in sex-/gender-sensitive parameters.

Activation of ERβ modulates fear generalization through an effect on memory retrieval

Women are 60% more likely to suffer from an anxiety disorder than men. One hypothesis for this difference may be that females exhibit increased rates of fear generalization. Females generalize fear to a neutral context faster than males, a process driven, in part, by estrogens. In the current study, ovariectomized adult female Long-Evans rats were given acute injections of estradiol benzoate (15μg/0.1mL sesame oil) or sesame oil during a passive avoidance procedure to determine if estrogens increase fear generalization through an effect on fear memory acquisition/consolidation or through fear memory retrieval. Animals injected 1h prior to training generalized to the neutral context 24h later but not 7days after training. Generalization was also seen when injections occurred 24h before testing, but not when tested at immediate (1h) or intermediate (6h) time points. In Experiment 3, animals were injected with estrogen receptor (ER) agonists, PPT or DPN, to determine which ER subtype(s) increased fear generalization. Only the ERβ agonist, DPN, increased fear generalization when testing occurred 24h after injection. Our results indicate that estradiol increases fear generalization through an effect on fear memory retrieval mechanisms by activation of ERβ.

Genistein partly eases aging and estropause-induced primary cortical neuronal changes in rats

Gonadal hormones can modulate brain morphology and behavior. Recent studies have shown that hypogonadism could result in cortical function deficits. To this end, hormone therapy has been used to ease associated symptoms but the risk may outweigh the benefits. Here we explored whether genistein, a phytoestrogen, is effective in restoring the cognitive and central neuronal changes in late middle age and surgically estropause female rats. Both animal groups showed poorer spatial learning than young adults. The dendritic arbors and spines of the somatosensory cortical and CA1 hippocampal pyramidal neurons were revealed with intracellular dye injection and analyzed. The results showed that dendritic spines on these neurons were significantly decreased. Remarkably, genistein treatment rescued spatial learning deficits and restored the spine density on all neurons in the surgically estropause young females. In late middle age females, genistein was as effective as estradiol in restoring spines; however, the recovery was less thorough than on young OHE rats. Neither genistein nor estradiol rectified the shortened dendritic arbors of the aging cortical pyramidal neurons suggesting that dendritic arbors and spines are differently modulated. Thus, genistein could work at central level to restore excitatory connectivity and appears to be potent alternative to estradiol for easing aging and menopausal syndromes.

Phytoestrogens β -sitosterol and genistein have limited effects on reproductive endpoints in a female fish, Betta splendens

Phytoestrogens are produced by plants and may cause endocrine disruption in vertebrates. The present study hypothesizes that phytoestrogen exposure of female Siamese fighting fish (Betta splendens) may disrupt endogenous steroid levels, change agonistic behavior expression, and potentially also disrupt oocyte development. However, only the pharmacologic dose of β-sitosterol had a significant effect on opercular flaring behavior, while we did not find significant effects of β-sitosterol or genistein on steroids or gonads. These findings are in direct contrast with previous studies on the effects of phytoestrogens in female fish. Results of the current study support previous work showing that the effects of phytoestrogen exposure may be less acute in mature female B. splendens than in other fish.

Phytoestrogens mediated anti-inflammatory effect through suppression of IRF-1 and pSTAT1 expressions in lipopolysaccharide-activated microglia

Microglial activation has been implicated in various neurological disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and HIV encephalopathy. Phytoestrogens have been shown to be neuroprotective in neurotoxicity models; however, their effect on microglia has not been well established. In the current study, we report that the soy phytoestrogens, genistein, daidzein, and coumestrol, decreased nitric oxide (NO) production induced by lipopolysaccharide (LPS) in the rat microglial cell line (HAPI). The levels of inducible NO synthase (iNOS) mRNA and protein expression were also reduced. Transcription factors known to govern iNOS expression including interferon regulatory factor-1 (IRF-1) and phosphorylated STAT1 were down regulated. These observations explain, at least in part, the inhibitory effect of phytoestrogens on NO production. The levels of monocyte chemoattractant protein-1 and interleukin-6 mRNA, proinflammatory chemokine and cytokine associated with various neurological disorders, were also reduced following LPS stimulation when HAPI cells were pretreated with phytoestrogens. Hence, genistein, daidzein, and coumestrol could serve as anti-inflammatory agents and may have beneficial effects in the treatment of neurodegenerative diseases.

Location- and sex-specific differences in weight and motor coordination in two commonly used mouse strains

Several studies have shown that environmental factors can affect the outcome of behavioral experiments, shedding doubts on the inter-laboratory reproducibility of behavioral test results. When our laboratory moved from the University of Rochester, Rochester, NY, to Sanford Research in Sioux Falls, SD, our mouse colony was also transferred and the new environment caused strain-dependent changes in the weight, motor coordination and motor learning capability of mice. Here we report the observed changes for two wild type mouse strains commonly used in transgenic studies, C57BL/6J and 129S6/SvEv, and show that the type of rodent diet is partially responsible for the geographical location-specific differences. We also found sex-specific differences in weight and motor coordination in both mouse strains. Our results show that environmental factors specific to a geographical location can change the body weight, motor coordination and motor learning capability of wild type mice commonly used as controls in transgenic studies.

Effects of perinatal daidzein exposure on subsequent behavior and central estrogen receptor α expression in the adult male mouse

Daidzein is one of the most important isoflavones present in soy and it is unique as it can be further metabolized to equol, a compound with greater estrogenic activity than other isoflavones. The potential role of daidzein in the prevention of some chronic diseases has drawn public attention and increased its consumption in human, including in pregnant women and adolescent. It is unclear whether perinatal exposure to daidzein through maternal diets affects subsequent behavior and central estrogen receptor α (ERα) expression in male adults. Following developmental exposure to daidzein through maternal diets during perinatal period, subsequent anxiety-like behavior, social behavior, spatial learning and memory of male mice at adulthood were assessed using a series of tests. The levels of central ER α expression were also examined using immunocytochemistry. Compared with the controls, adult male mice exposed to daidzein during the perinatal period showed significantly less exploration, higher levels of anxiety and aggression. They also displayed more social investigation for females and a tendency to improve spatial learning and memory. The mice with this early daidzein treatment demonstrated significantly higher levels of ERα expression in several brain regions such as the bed nucleus of the stria terminalis, medial preoptic, arcuate hypothalamic nucleus and central amygdaloid mucleus, but decreased it in the lateral septum. Our results indicated that perinatal exposure to daidzein enhanced masculinization on male behaviors which is assocciated with alterations in ERα expression levels led by perinatal daidzein exposure.

Soy isoflavone: The multipurpose phytochemical (Review)

Soy isoflavones are compounds found in soybean and soybean products. They have been reported to possess numerous physiological properties, such as antitumor, anti-menopausal (female) osteoporosis and anti-aging. They have also been reported to improve learning and memory skills in menopausal women and aid in the prevention and treatment of heart disease, diabetes and Kawasaki disease (KD). In this review, the effects of soy isoflavones on various diseases were analyzed. Based on the analysis, it was hypothesized that the function of soybean isoflavones in the prevention and treatment of various diseases results from their phytoestrogen and antioxidant properties. However, due to their phytoestrogen properties, it is recommended that the risks of soy isoflavone intake as food and/or medical treatment be further evaluated.