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Neese SL, Wang VC, Doerge DR, Woodling KA, Andrade JE, Helferich WG, Korol DL, Schantz SL. Impact of dietary genistein and aging on executive function in rats. Neurotoxicol Teratol 2010; 32:200-11. [PMID: 19945528 PMCID: PMC2860723 DOI: 10.1016/j.ntt.2009.11.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 11/10/2009] [Accepted: 11/19/2009] [Indexed: 12/29/2022]
Abstract
Genistein is an estrogenic soy isoflavone widely promoted for healthy aging, but its effects on cognitive function are not well-understood. We examined the cognitive effects of once daily oral genistein treatment at two doses (approximately 162 microg/kg/day low dose and a 323 microg/kg/day high dose) in ovariectomized young (7 month), middle-aged (16 month), and old (22 month) Long-Evans rats. Operant tasks including delayed spatial alternation (DSA), differential reinforcement of low rates of responding (DRL), and reversal learning that tap prefrontal cortical function were used to assess working memory, inhibitory control/timing, and strategy shifting, respectively. At the conclusion of cognitive testing, brains were collected and relative densities of D1 and D2 dopamine receptors and dopamine transporter (DAT) were measured in the prefrontal cortex. On the DSA task, the high dose old group performed worse than both the high dose young and middle-aged groups. On the DRL task, the high dose of genistein resulted in a marginally significant impairment in the ratio of reinforced to non-reinforced lever presses. This effect was present across age groups. Age effects were also found as old rats performed more poorly than the young and middle-aged rats on the DSA overall. In contrast, middle-aged and old rats made fewer lever presses on the DRL than did the young rats, a pattern of behavior associated with better performance on this task. Moreover, while DAT levels overall decreased with age, genistein treatment produced an increase in DAT expression in old rats relative to similarly aged control rats. D1 and D2 densities did not differ between genistein dose groups or by age. These results highlight the fact that aspects of executive function are differentially sensitive to both genistein exposure and aging and suggest that altered prefrontal dopamine function could potentially play a role in mediating these effects.
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Affiliation(s)
- Steven L. Neese
- Department of Veterinary Sciences, University of Illinois at Urbana-Champaign. 2001 S. Lincoln Avenue, Urbana, IL 61802, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign. 505 South Goodwin Avenue, Urbana, IL 61801, USA
| | - Victor C. Wang
- Department of Veterinary Sciences, University of Illinois at Urbana-Champaign. 2001 S. Lincoln Avenue, Urbana, IL 61802, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign. 505 South Goodwin Avenue, Urbana, IL 61801, USA
| | - Daniel R. Doerge
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration. 3900 NCTR Road, Jefferson, AR 72079-9502, USA
| | - Kellie A. Woodling
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration. 3900 NCTR Road, Jefferson, AR 72079-9502, USA
| | - Juan E. Andrade
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign. 905 S. Goodwin Avenue, Urbana, IL 61801, USA
| | - William G. Helferich
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign. 905 S. Goodwin Avenue, Urbana, IL 61801, USA
| | - Donna L. Korol
- Neuroscience Program, University of Illinois at Urbana-Champaign. 505 South Goodwin Avenue, Urbana, IL 61801, USA
- Department of Psychology, University of Illinois at Urbana-Champaign. 603 East Daniel Street, Champaign, IL 61820, USA
- Institute for Genomic Biology Department of Veterinary Sciences, University of Illinois at Urbana-Champaign. 1206 West Gregory Drive, Urbana, IL 61801, USA
| | - Susan L. Schantz
- Department of Veterinary Sciences, University of Illinois at Urbana-Champaign. 2001 S. Lincoln Avenue, Urbana, IL 61802, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign. 505 South Goodwin Avenue, Urbana, IL 61801, USA
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Mortensen A, Kulling SE, Schwartz H, Rowland I, Ruefer CE, Rimbach G, Cassidy A, Magee P, Millar J, Hall WL, Kramer Birkved F, Sorensen IK, Sontag G. Analytical and compositional aspects of isoflavones in food and their biological effects. Mol Nutr Food Res 2009; 53 Suppl 2:S266-309. [PMID: 19774555 DOI: 10.1002/mnfr.200800478] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This paper provides an overview of analytical techniques used to determine isoflavones (IFs) in foods and biological fluids with main emphasis on sample preparation methods. Factors influencing the content of IFs in food including processing and natural variability are summarized and an insight into IF databases is given. Comparisons of dietary intake of IFs in Asian and Western populations, in special subgroups like vegetarians, vegans, and infants are made and our knowledge on their absorption, distribution, metabolism, and excretion by the human body is presented. The influences of the gut microflora, age, gender, background diet, food matrix, and the chemical nature of the IFs on the metabolism of IFs are described. Potential mechanisms by which IFs may exert their actions are reviewed, and genetic polymorphism as determinants of biological response to soy IFs is discussed. The effects of IFs on a range of health outcomes including atherosclerosis, breast, intestinal, and prostate cancers, menopausal symptoms, bone health, and cognition are reviewed on the basis of the available in vitro, in vivo animal and human data.
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Affiliation(s)
- Alicja Mortensen
- The National Food Institute, Technical University of Denmark, Søborg, Denmark
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53
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Cassidy A. Dietary phyto-oestrogens: molecular mechanisms, bioavailability and importance to menopausal health. Nutr Res Rev 2009; 18:183-201. [PMID: 19079904 DOI: 10.1079/nrr2005102] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Following the high-profile studies on hormone replacement therapy which provided little evidence in support of the drug therapy improving future health, there remains a growing demand for dietary solutions for maintaining health and preventing disease as women age. Although interest in the relative importance of phyto-oestrogens to human health has increased dramatically over the last decade, the effective dose for health benefits and hypothetical issues on safety remain to be resolved. Plausible mechanisms and epidemiological data are available to support the concept that phyto-oestrogen-rich diets exert physiological effects, but optimal doses and sources of these compounds have still not been elucidated for specific health benefits. In addition, much of the current mechanistic data are difficult to interpret as the experiments have incorporated levels of phyto-oestrogens that may not be achievable in vivo and have to date only used aglycones and glycosides of the pure compounds rather than examining the biological effects of gut and liver metabolites. The present review will concentrate on the isoflavone subclass of phyto-oestrogens, as, to date, these compounds have received most attention from both a commercial and research perspective.
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Affiliation(s)
- Aedín Cassidy
- School of Medicine, Health Policy and Practice, University of East Anglia, Norwich NR4 7TJ, UK.
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54
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Thorp AA, Sinn N, Buckley JD, Coates AM, Howe PRC. Soya isoflavone supplementation enhances spatial working memory in men. Br J Nutr 2009; 102:1348-54. [PMID: 19480732 DOI: 10.1017/s0007114509990201] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Females perform better in certain memory-related tasks than males. Sex differences in cognitive performance may be attributable to differences in circulating oestrogen acting on oestrogen beta receptors (ERbeta) which are prevalent in brain regions such as the hippocampus, frontal lobe and cortex that mediate cognitive functions. Since soya isoflavones are known to activate ERbeta, chronic isoflavone supplementation in males may improve cognitive performance in memory-related tasks. A 12-week double-blind, placebo-controlled cross-over trial was conducted in thirty-four healthy men to investigate the effect of isoflavone supplementation on cognitive function. Volunteers were randomised to take four capsules/d containing soya isoflavones (116 mg isoflavone equivalents/d: 68 mg daidzein, 12 mg genistein, 36 mg glycitin) or placebo for 6 weeks, and the alternate treatment during the following 6 weeks. Assessments of memory (verbal episodic, auditory and working), executive function (planning, attention, mental flexibility) and visual-spatial processing were performed at baseline and after each treatment period. Isoflavone supplementation significantly improved spatial working memory (P = 0.01), a test in which females consistently perform better than males. Compared with placebo supplementation, there were 18 % fewer attempts (P = 0.01), 23 % fewer errors (P = 0.02) and 17 % less time (P = 0.03) required to correctly identify the requisite information. Isoflavones did not affect auditory and episodic memory (Paired Associate Learning, Rey's Auditory Verbal Learning Task, Backward Digit Span and Letter-Number Sequencing), executive function (Trail Making and Initial Letter Fluency Task) or visual-spatial processing (Mental Rotation Task). Isoflavone supplementation in healthy males may enhance cognitive processes which appear dependent on oestrogen activation.
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Affiliation(s)
- Alicia A Thorp
- Nutritional Physiology Research Centre and ATN Centre for Metabolic Fitness, Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia
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55
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Barker JM, Galea LAM. Sex and regional differences in estradiol content in the prefrontal cortex, amygdala and hippocampus of adult male and female rats. Gen Comp Endocrinol 2009; 164:77-84. [PMID: 19457436 DOI: 10.1016/j.ygcen.2009.05.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 05/09/2009] [Accepted: 05/12/2009] [Indexed: 12/11/2022]
Abstract
In general, the behavioral and neural effects of estradiol administration to males and females differ. While much attention has been paid to the potential structural, cellular and sub-cellular mechanisms that may underlie such differences, as of yet there has been no examination of whether the differences observed may be related to differential uptake or storage of estradiol within the brain itself. We administered estradiol benzoate to gonadectomized male and female rats, and compared the concentration of estradiol in serum and brain tissue found in these rats to those of gonadectomized, oil-treated rats and intact rats of both sexes. Long-term gonadectomy (3 weeks) reduced estradiol concentration in the male and female hippocampus, but not in the male or female amygdala or in the female prefrontal cortex. Furthermore, exogenous treatment with estradiol increased estradiol content to levels above intact animals in the amygdala, prefrontal cortex and the male hippocampus. Levels of estradiol were undetectable in the prefrontal cortex of intact males, but were detectable in all other brain regions of intact rats. Here we demonstrate (1) that serum concentrations of estradiol are not necessarily reflective of brain tissue concentrations, (2) that within the brain, there are regional differences in the effects of gonadectomy and estradiol administration, and (3) that there is less evidence for local production of estradiol in males than females, particularly in the prefrontal cortex and perhaps the hippocampus. Thus there are regional differences in estradiol concentration in the prefrontal cortex, amygdala and hippocampus that are influenced by sex and hormone status.
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Affiliation(s)
- Jennifer M Barker
- Graduate Program in Neuroscience, Brain Research Centre, Department of Psychology, University of British Columbia, British Columbia, Canada
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56
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Lee YB, Lee KH, Sohn HS, Lee SJ, Cho KH, Kang IJ, Kim DW, Shin YK, Pai T, Hwang IK, Won MH. Effects of soy phytoestrogens on reference memory and neuronal cholinergic enzymes in ovariectomized rats. J Med Food 2009; 12:64-70. [PMID: 19298197 DOI: 10.1089/jmf.2007.0633] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The effects of soy phytoestrogens on Morris water maze (MWM) performance and neuronal cholinergic enzyme activities and immunoreactivity were studied in ovariectomized (OVX) rats. The rats were assigned to four groups fed control diet (CD), 3.9 mg/kg 17beta-estradiol diet (E2), 263.4 mg/kg soy phytoestrogens diet (SP1), and 526.9 mg/kg soy phytoestrogens diet (SP2). In the MWM task, escape latency and path length were significantly less in the E2 and SP2 groups than in the CD group on the second day. Choline acetyltransferase (ChAT) activity in the cerebral cortex and ChAT immunoreactivity in the diagonal band of Broca were significantly greater in the E2, SP1, and SP2 groups than in the CD group. Acetylcholinesterase activity in the hippocampus in the E2, SP1, and SP2 groups was significantly lower than in the CD group. This study suggests that soy phytoestrogens affect the reference memory and neuronal cholinergic system in OVX rats.
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Affiliation(s)
- Yoon-Bok Lee
- Central Research Institute, Dr. Chung's Food Co. Ltd., Cheongju, Republic of Korea
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57
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Erratum: Analytical and compositional aspects of isoflavones in food and their biological effects. Mol Nutr Food Res 2009. [DOI: 10.1002/mnfr.200700478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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58
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OHTA R, SHIROTA M, KANAZAWA Y, SHINDO T, FURUYA M, SEKI T, ONO H, KOJIMA K, ASAI S, WATANABE G, TAYA K. Effects of Transmaternal Exposure to Genistein in Hatano High- and Low-Avoidance Rats. Exp Anim 2009; 58:471-9. [DOI: 10.1538/expanim.58.471] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Affiliation(s)
- Ryo OHTA
- Hatano Research Institute, Food and Drug Safety Center
| | | | | | - Tomoko SHINDO
- Hatano Research Institute, Food and Drug Safety Center
| | - Mami FURUYA
- Hatano Research Institute, Food and Drug Safety Center
| | - Takayuki SEKI
- Hatano Research Institute, Food and Drug Safety Center
| | - Hiroshi ONO
- Hatano Research Institute, Food and Drug Safety Center
| | | | - Sayaka ASAI
- Faculty of Agriculture, Tokyo University of Agriculture and Technology
| | - Gen WATANABE
- Faculty of Agriculture, Tokyo University of Agriculture and Technology
| | - Kazuyoshi TAYA
- Faculty of Agriculture, Tokyo University of Agriculture and Technology
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59
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Monteiro SC, de Mattos CB, Ben J, Netto CA, Wyse ATS. Ovariectomy impairs spatial memory: prevention and reversal by a soy isoflavone diet. Metab Brain Dis 2008; 23:243-53. [PMID: 18648916 DOI: 10.1007/s11011-008-9093-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 04/01/2008] [Indexed: 02/05/2023]
Abstract
Since a previous study has shown that ovariectomy impairs spatial memory, we, herein, investigate the influence of pre- and post-treatment with a soy diet on the effects elicited by ovariectomy on spatial memory. In the pre-treatment, 20-day-old female Wistar rats were first fed for 60 days on a standard diet with casein (control) or a soy diet. At 80 days of age, the animals were assigned to one of the following groups: sham (submitted to surgery without removal of ovaries) and ovariectomized. One week after surgery, the rats were submitted to behavioral testing. In the post-treatment, 80-day-old female rats were assigned to one of the following groups: sham and ovariectomized. One week after surgery, animals were fed for 30 days with the same diet described above. Then, rats were submitted to water maze testing. Pre-treatment for two months before ovariectomy with the soy diet effectively prevented the increase in latency in finding the platform on the fifth day of training in the ovariectomized group. Ovariectomized rats subjected to soy diet post-treatment reversed the increase in latency to find the platform in the ovariectomized group on the fifth day of training and, the decrease in the time spent in target quadrant, the increase in the time spent in opposite quadrant and the latency to cross the platform location. Results show that both pre- and post-treatment protected against the impairment of memory, caused by ovariectomy. Post-treatment reversed various parameters of memory reference, indicating that post-treatment was more efficient than pre-treatment. Based on these findings, we suggest that soy diet (rich in isoflavones) may represent a novel therapeutic strategy to prevent or to treat cognitive symptoms found in some menopausal women.
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Affiliation(s)
- Siomara C Monteiro
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcellos, 2600-Anexo, CEP 90035-003, Porto Alegre, Rio Grande do Sul, Brazil
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60
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Walf AA, Koonce CJ, Frye CA. Estradiol or diarylpropionitrile administration to wild type, but not estrogen receptor beta knockout, mice enhances performance in the object recognition and object placement tasks. Neurobiol Learn Mem 2008; 89:513-21. [PMID: 18313947 DOI: 10.1016/j.nlm.2008.01.008] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Revised: 01/17/2008] [Accepted: 01/17/2008] [Indexed: 11/18/2022]
Abstract
Cognitive processes mediated by the hippocampus and cortex are influenced by estradiol (E(2)); however, the mechanisms by which E(2) has these effects are not entirely clear. As such, studies were conducted to begin to address the role of actions at the beta form of the intracellular estrogen receptor (ERbeta) for E(2)'s cognitive effects in adult female mice. We investigated whether E(2) improved performance of wild type (WT) and ERbeta knockout (betaERKO) mice in tasks considered to be mediated by the cortex and hippocampus, the object recognition and object placement tasks. WT and betaERKO mice were ovariectomized (ovx) and E(2) (0.1 mg/kg), an ERbeta selective ER modulator (SERM), diarylpropionitrile (DPN; 0.1 mg/kg), or oil vehicle was administered to mice following training in these tasks. We hypothesized that if E(2) has mnemonic effects, in part, due to its actions at ERbeta, then WT mice administered E(2) or DPN would have improved performance compared to vehicle WT controls, which would not be different from betaERKO mice administered vehicle, E(2) or DPN. Alternatively, activation of ERalpha (with E(2), which is a ligand for both ERalpha and ERbeta) may produce opposing effects on cognition and/or the activation of ERalpha and ERbeta vs. either receptor isoform alone may produce a different pattern of effects. Results obtained supported the hypothesis that ERbeta activation is important for mnemonic effects. Ovx WT, but not betaERKO, mice administered E(2) or DPN had a greater percentage of time exploring a novel object in the object recognition task and a displaced object in the object placement task. Thus, actions at ERbeta may be important for E(2) or SERMs to enhance cognitive performance of female mice in the object recognition and placement tasks.
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Affiliation(s)
- Alicia A Walf
- Department of Psychology, The University at Albany, State University of New York, Albany, NY 12222, USA
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61
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Zhao L, Brinton RD. WHI and WHIMS follow-up and human studies of soy isoflavones on cognition. Expert Rev Neurother 2008; 7:1549-64. [PMID: 17997703 DOI: 10.1586/14737175.7.11.1549] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recent follow-up analyses of the previous findings from the Women's Health Initiative and the Women's Health Initiative Memory Study confirmed some health benefits of estrogen-containing hormone therapy (HT) in women within 10 years from the onset of menopause. However, the potential risks associated with long-term administration of HT, such as breast cancer and stroke, remain a concern for therapy recipients, underlying the need for an alternative treatment that is functionally equivalent but with a greater safety profile. Owing to their structural and functional resemblance to mammalian estrogens and lack of evident adverse effects, research interest in plant-derived phytoestrogens has increased in the past decade. While multiple health-promoting benefits of phytoestrogens have been proposed from basic science, the clinical data remain inconclusive. This review provides a comparative analysis of human studies on the effects of soy-based isoflavones on cognition. Of the eight studies published in 2000-2007, seven were conducted in postmenopausal women, four of which revealed a positive impact of isoflavones on cognitive function. Multiple factors could have contributed to the discrepant outcomes across studies, such as variation in the composition of phytoestrogen interventions and the heterogeneous characteristics of the study population. Thus, a well-designed clinical study based on a standardized stable formulation in a well-characterized study population is required in order to reach a clinical consensus. A formulation composed of select estrogen receptor beta-selective phytoestrogens with a rationally designed composition would avoid the potential antagonism present in a mixture and thus enhance therapeutic efficacy. In addition, inclusion of equol in a study formulation offers a potential synergistic effect from equol in both equol-producing and nonproducing individuals, as well as added benefits for men. With respect to the design of study population, a clinically consistent effect could potentially be achieved by stratifying populations based on genotype, age, hormonal history and even diets. Development of an effective phytoestrogen formulation would benefit both women and men to prevent or treat hormone-dependent conditions and, most of all, to improve neurological health and reduce the risk of Alzheimer's disease.
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Affiliation(s)
- Liqin Zhao
- Department of Pharmacology & Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA.
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62
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Ostatníková D, Celec P, Hodosy J, Hampl R, Putz Z, Kúdela M. Short-term soybean intake and its effect on steroid sex hormones and cognitive abilities. Fertil Steril 2007; 88:1632-6. [PMID: 17517399 DOI: 10.1016/j.fertnstert.2007.01.106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2006] [Revised: 01/22/2007] [Accepted: 01/22/2007] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To observe the effects of short-term soybean consumption on cognitive spatial abilities and changes in sex endocrine net in both genders. DESIGN Short-term prospective intervention study. SETTING Academic medical center. PATIENT(S) Fifty-four healthy females and 32 healthy males (18 - 25 y of age). INTERVENTION(S) Volunteers were asked to eat 2 g/kg per day of soybeans during 1 week. Saliva and plasma samples were taken, and psychometric tests were performed on the 1st (before soybean intake), 7th (after soybean intake), and 14th days (after washout period) of the study. MAIN OUTCOME MEASURE(S) Salivary T and plasma E(2) were measured. Mental rotation (MR) and spatial visualization (SV) tests were performed on the days of sampling. RESULT(S) Soybean intake did not change salivary T and plasma E(2) levels in men. During the washout period, both parameters have shown a tendency to rise. The effect of soybean intake on hormonal parameters in men was, however, dependent on the basal T levels. In women, salivary T as well as plasma E(2) levels showed a tendency toward a decline after soybean intake (the decrease in E(2) was statistically significant) and to increase back toward basal levels during the washout period. Both males and females statistically significantly improved in MR and SV after soybean intake. During the washout period, both genders further improved their results in MR but not in SV. CONCLUSION(S) Short-term soybean consumption alters the concentrations of salivary T and plasma E(2) in both men and women. Spatial abilities appear to be improved by short-term soybean intake, but the exact mechanisms require further study.
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63
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Lovekamp-Swan T, Glendenning ML, Schreihofer DA. A high soy diet enhances neurotropin receptor and Bcl-XL gene expression in the brains of ovariectomized female rats. Brain Res 2007; 1159:54-66. [PMID: 17582385 PMCID: PMC1995131 DOI: 10.1016/j.brainres.2007.05.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 04/25/2007] [Accepted: 05/20/2007] [Indexed: 10/23/2022]
Abstract
Estrogen is a powerful neuroprotective agent with the ability to induce trophic and antiapoptotic genes. However, concerns about negative overall health consequences of estrogen replacement after menopause have led to the adoption of other strategies to obtain estrogen's benefits in the brain, including the use of selective estrogen receptor modulators, high soy diets, or isoflavone supplements. This study sought to determine the ability of a high soy diet to induce neuroprotective gene expression in the female rat brain and compare the actions of soy with estrogen. Adult ovariectomized female rats were treated with 3 days of high dose estrogen or 2 weeks of a soy-free diet, a high soy diet, or chronic low dose estrogen. Different brain regions were microdissected and subjected to real time RT-PCR for neuroprotective genes previously shown to be estrogen-regulated. The principle findings are that a high soy diet led to the widespread increase in the mRNA for neurotropin receptors TrkA and p75-NTR, and the antiapoptotic Bcl-2 family member Bcl-X(L). Immunohistochemistry confirmed increases in both TrkA and Bcl-X(L). Chronic low dose estrogen mimicked some of these effects, but acute high dose estrogen did not. The effects of a high soy diet were particularly evident in the parietal cortex and hippocampus, two regions protected by estrogen in animal models of neurological disease and injury. These results suggest that a high soy diet may provide beneficial effects to the brain similar to low dose chronic estrogen treatment such as that used for postmenopausal hormone replacement.
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Affiliation(s)
- Tara Lovekamp-Swan
- Department of Physiology, Medical College of Georgia, 1120 15th Street, Augusta, GA 30912-3000
| | - Michele L. Glendenning
- Department of Physiology, Medical College of Georgia, 1120 15th Street, Augusta, GA 30912-3000
| | - Derek A. Schreihofer
- Department of Physiology, Medical College of Georgia, 1120 15th Street, Augusta, GA 30912-3000
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64
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Young GS, Kirkland JB. Rat models of caloric intake and activity: relationships to animal physiology and human health. Appl Physiol Nutr Metab 2007; 32:161-76. [PMID: 17486157 DOI: 10.1139/h06-082] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Every rodent experiment is based on important parameters concerning the levels of caloric intake and physical activity. In many cases, these decisions are not made consciously, but are based on traditional models. For experimental models directed at the study of caloric intake and activity, the selection of parameters is usually aimed at modeling human conditions, the ultimate goal of which is to gain insight into the pathophysiology of the disease process in man. In each model, it is important to understand the influence of diet, exercise, and genetic background on physiology and the development of disease states. Along the continuum of energy intake from caloric restriction to high-fat feeding, and of energy output from total inactivity to forced exercise, a number of models are used to study different disease states. In this paper, we will evaluate the influence of the quantity and composition of diet and exercise in several animal models, and will discuss how each model can be applied to various human conditions. This review will be limited to traditional models using the rat as the experimental animal, and although it is not an exhaustive list, the models presented are those most commonly represented in the literature. We will also review the mechanisms by which each affects rat physiology, and will compare these to the analogous mechanisms in the modeled human disease state. We hope that the information presented here will help researchers make choices among the available models and will encourage discussion on the interpretation and extrapolation of results obtained from traditional and novel rodent experiments on diet, exercise, and chronic disease.
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Affiliation(s)
- Genevieve S Young
- Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
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65
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Xu J, Zhu J, Shi C, Guo K, Yew DT. Effects of genistein on hippocampal neurodegeneration of ovariectomized rats. J Mol Neurosci 2007. [DOI: 10.1385/jmn/31:02:101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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66
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Xu J, Zhu J, Shi C, Guo K, Yew DT. Effects of genistein on hippocampal neurodegeneration of ovariectomized rats. J Mol Neurosci 2007; 31:101-12. [PMID: 17478884 DOI: 10.1007/s12031-007-0010-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2006] [Revised: 11/30/1999] [Accepted: 11/01/2006] [Indexed: 10/23/2022]
Abstract
To investigate the mechanism underlying the neurodegeneration of postmenopausal women, the effect of genistein on hippocampal neurodegeneration was investigated in ovariectomized (OVX) Sprague-Dawley rats. Three-month-old female Sprague-Dawley rats were randomly divided into four groups: sham operated; OVX only; genistein-treated OVX (OVX-genistein); and estradiol benzoate-treated OVX (OVX-EB). Genistein and EB were subcutaneously injected into rats of the OVX-genistein and OVX-EB groups, respectively, once a day from the second day after surgery. Behavioral testing began on day 31 after surgery and lasted 5 d. The activities of superoxide dismutase and content of malondialdehyde in serum, the concentration of intrasynaptosome-free calcium, membrane relative viscosity of cerebral synaptosomes, and mean optical density (MOD) of the hippocampal synaptophysin immunoreactivity product were measured, respectively, in the eighth week after surgery. It was found that the escape latency in the OVX-EB and the OVX-genistein groups was significantly lower than that in the OVX control group (p < 0.05), whereas in the behavioral test, the platform-passing number was higher than in the OVX control group (p < 0.05). [Ca2+]i in the cerebral cortical and hippocampal synaptosome of the OVX-only group was remarkably higher than that in the other three groups ( p < 0.01). The hippocampal synaptosome membrane viscosity of the OVX-only group was significantly higher than that in the sham-operated, OVX-EB (p < 0.05) and the OVX-genistein (p < 0.01) groups. The MOD of synaptophysin immunoreactive product in the radiation layers of CA1, CA2, CA3 and the molecular layer of the dentate gyrus of the OVX-only group was significantly lower than in the sham-operated, OVX-genistein, and OVX-EB groups (p < 0.01). These results suggested that genistein, which has antioxidant properties similar to estradiol, could be used as a substitute for estradiol to prevent or treat central neurodegeneration in postmenopausal women.
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Affiliation(s)
- Jie Xu
- Department of Anatomy, Zhongshan Medical College, Sun Yat-Sen University, Guangzhou, Guangdong 510080, China.
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67
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Bu L, Lephart ED. Regulatory behavior and skin temperature in mid-aged male rats on three different isoflavone-containing diets. J Med Food 2007; 9:567-71. [PMID: 17201646 DOI: 10.1089/jmf.2006.9.567] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Soy isoflavones, the most abundant phytoestrogens, are known as endocrine modulators and appear to be an effective treatment in some women during perimenopause when symptoms such as hot flashes may be reduced. This study examined the effects of dietary soy isoflavones on regulatory behaviors such as body weight, food and water intake, and skin tail temperature by feeding male Long-Evans rats one of the three standard chows (Phyto-free, Phyto-200, and Phyto-600) containing approximately 10-15 ppm, 200 ppm, and 600 ppm of isoflavones, respectively. In an apparent dose-dependent manner, body weight was decreased as a function of increasing isoflavone levels in the diets. The average skin tail temperature of Phyto-600-fed rats (25.5 degrees C) was significantly lower than Phyto-free (27.5 degrees C) values by approximately 2 degrees C. The rats on the Phyto-200 diet (26.6 degrees C) displayed a temperature in between the Phyto-free and Phyto-600 values. Similar to the body weight results, skin tail temperature was decreased in an apparent dose-dependent manner as a function of increasing isoflavone concentrations in the diets. These results suggest that consumption of soy isoflavones alters regulatory behaviors (such as body weight and food and water intake) and skin temperature regulation that may help explain, in part, the beneficial effects of soy isoflavones on obesity and hot flashes in humans.
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Affiliation(s)
- Lihong Bu
- Department of Physiology and Developmental Biology and the Neuroscience Center, Brigham Young University, Provo, UT 84602, USA
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68
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Liu YQ, Xin TR, Lü XY, Ji Q, Jin Y, Yang HD. Memory performance of hypercholesterolemic mice in response to treatment with soy isoflavones. Neurosci Res 2007; 57:544-9. [PMID: 17289196 DOI: 10.1016/j.neures.2006.12.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 12/19/2006] [Accepted: 12/26/2006] [Indexed: 11/20/2022]
Abstract
The aim of this study is to investigate the memory performance of hypercholesterolemic mice in response to soy isoflavones (SI) treatment and the mechanism involved. In this study, 64 mice were randomly divided into four groups: control, high lipid diet without SI, high lipid diet with a low SI level (50 mg/kg bw) and high lipid diet with a high SI level (100 mg/kg bw). The experimental period was 30 days. The results indicated that the mice given the different treatments showed the different percentages of good, medium and poor memory performance. chi(2) analysis revealed significant difference in memory performance (P<0.05) between the high lipid diet without SI group and the high lipid diet with a low SI level group or high lipid diet with a high SI level group. Moreover, SI treatment resulted in a decrease in blood cholesterol (TC) level (high lipid diet without SI group versus high lipid diet with a low SI level group or high lipid diet with a high SI level group, P<0.05) and triglyceride (TG) level (high lipid diet without SI group versus high lipid diet with a low SI level group or high lipid diet with a high SI level group, P<0.05). In addition, SI treatment resulted in a significant decrease in acetylcholinesterase (AChE) activity and significant increases in glutamic acid and aspartic acid contents in the frontal cerebral cortex and hippocampus. The results suggest that SI improve the memory performance of hypercholesterolemic mice, and the mechanism underlying the improvement might closely correlate with its roles in decreasing high blood lipid levels and modulating the metabolism of neurotransmitters such as acetylcholine and amino acids in brain areas of hypercholesterolemic mice.
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Affiliation(s)
- Yan-qiang Liu
- College of Life Sciences, Nankai University, Tianjin 300071, PR China.
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69
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Imwalle DB, Bateman HL, Wills A, Honda SI, Harada N, Rissman EF. Impairment of spatial learning by estradiol treatment in female mice is attenuated by estradiol exposure during development. Horm Behav 2006; 50:693-8. [PMID: 16884724 DOI: 10.1016/j.yhbeh.2006.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Revised: 05/15/2006] [Accepted: 06/06/2006] [Indexed: 10/24/2022]
Abstract
High doses of estradiol (E(2)) can impair spatial learning in the Morris water maze, in ovariectomized mice, but the same dose has no effect on adult castrated males. Here, we test the hypothesis that this sex difference is caused by neonatal actions of E(2). In Experiment 1, C57BL/6J pups were given daily estradiol benzoate (EB) or oil injections from the day of birth until postnatal Day 3. Adults were gonadectomized and received EB (s.c.) or oil 28 h before the first day of training, and 4 h before each of four daily training sessions on the Morris water maze. Females given oil as neonates, and EB prior to training displayed the poorest performance. Females that received EB as neonates and EB prior to training were insensitive to the deleterious effects of adult EB and performed better than males given the same hormone treatments. We conducted a second experiment using aromatase enzyme knockout (ArKO) mice. Adult male and female ArKO and wild-type (WT) littermates were gonadectomized and received either injections of oil or EB prior to and during water maze training (as described above). Hormone treatment failed to affect performance, yet, female but not male ArKO mice showed impaired learning compared to WT littermates. Thus, exposure to estradiol during neonatal development can counteract the deleterious effects of EB on adult spatial learning.
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Affiliation(s)
- D Bradley Imwalle
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908-0733, USA.
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70
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Rozman KK, Bhatia J, Calafat AM, Chambers C, Culty M, Etzel RA, Flaws JA, Hansen DK, Hoyer PB, Jeffery EH, Kesner JS, Marty S, Thomas JA, Umbach D. NTP-CERHR expert panel report on the reproductive and developmental toxicity of soy formula. ACTA ACUST UNITED AC 2006; 77:280-397. [PMID: 16998908 PMCID: PMC2266894 DOI: 10.1002/bdrb.20086] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Karl K Rozman
- Department of Pharmacology and Toxicology, University of Kansas Medical Center, Kansas City, KS, USA
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71
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Luine V, Attalla S, Mohan G, Costa A, Frankfurt M. Dietary phytoestrogens enhance spatial memory and spine density in the hippocampus and prefrontal cortex of ovariectomized rats. Brain Res 2006; 1126:183-7. [PMID: 16945354 DOI: 10.1016/j.brainres.2006.07.016] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 06/29/2006] [Accepted: 07/06/2006] [Indexed: 11/24/2022]
Abstract
Long-term maintenance of ovariectomized rats (9 weeks) on chow containing high phytoestrogen levels (Purina LabDiet 5001) as compared to chow with minimal phytoestrogens (Harlan 2016 Teklad) was associated with better performance of the spatial memory task, object placement, increased dendritic spine density in CA1 and prefrontal cortex pyramidal neurons, and higher uterine weights. Object recognition memory, anxiety on an elevated plus maze and body weight were unaffected by phytoestrogen levels in the diet.
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Affiliation(s)
- V Luine
- Department of Psychology, Hunter College of CUNY, 695 Park Ave., New York, NY 10021, USA.
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72
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de Fiebre NC, Sumien N, Forster MJ, de Fiebre CM. Spatial learning and psychomotor performance of C57BL/6 mice: age sensitivity and reliability of individual differences. AGE (DORDRECHT, NETHERLANDS) 2006; 28:235-53. [PMID: 22253492 PMCID: PMC3259155 DOI: 10.1007/s11357-006-9027-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2006] [Revised: 10/31/2006] [Accepted: 11/03/2006] [Indexed: 05/16/2023]
Abstract
Two tests often used in aging research, the elevated path test and the Morris water maze test, were examined for their application to the study of brain aging in a large sample of C57BL/6JNia mice. Specifically, these studies assessed: (1) sensitivity to age and the degree of interrelatedness among different behavioral measures derived from these tests, (2) the effect of age on variation in the measurements, and (3) the reliability of individual differences in performance on the tests. Both tests detected age-related deficits in group performance that occurred independently of each other. However, analysis of data obtained on the Morris water maze test revealed three relatively independent components of cognitive performance. Performance in initial acquisition of spatial learning in the Morris maze was not highly correlated with performance during reversal learning (when mice were required to learn a new spatial location), whereas performance in both of those phases was independent of spatial performance assessed during a single probe trial administered at the end of acquisition training. Moreover, impaired performance during initial acquisition could be detected at an earlier age than impairments in reversal learning. There were modest but significant age-related increases in the variance of both elevated path test scores and in several measures of learning in the Morris maze test. Analysis of test scores of mice across repeated testing sessions confirmed reliability of the measurements obtained for cognitive and psychomotor function. Power calculations confirmed that there are sufficiently large age-related differences in elevated path test performance, relative to within age variability, to render this test useful for studies into the ability of an intervention to prevent or reverse age-related deficits in psychomotor performance. Power calculations indicated a need for larger sample sizes for detection of intervention effects on cognitive components of the Morris water maze test, at least when implemented at the ages tested in this study. Variability among old mice in both tests, including each of the various independent measures in the Morris maze, may be useful for elucidating the biological bases of different aspects of dysfunctional brain aging.
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Affiliation(s)
- NancyEllen C. de Fiebre
- Department of Pharmacology & Neuroscience, Institute for Aging and Alzheimer’s Disease Research, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107-2699 USA
| | - Nathalie Sumien
- Department of Pharmacology & Neuroscience, Institute for Aging and Alzheimer’s Disease Research, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107-2699 USA
| | - Michael J. Forster
- Department of Pharmacology & Neuroscience, Institute for Aging and Alzheimer’s Disease Research, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107-2699 USA
| | - Christopher M. de Fiebre
- Department of Pharmacology & Neuroscience, Institute for Aging and Alzheimer’s Disease Research, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107-2699 USA
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73
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Hwang IK, Lee YB, Yoo KY, Kang TC, Lim SS, Sohn HS, Kim SM, Kim WJ, Shin HK, Won MH. Calbindin D-28k immunoreactivity increases in the hippocampus after long-term treatment of soy isoflavones in middle-aged ovariectomized and male rats. Int J Neurosci 2006; 116:991-1003. [PMID: 16861163 DOI: 10.1080/00207450600674806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
This article investigates the long-term effects of soybean isoflavones (ISO) on the changes of calbindin D-28k (CB) immunoreactivity in the hippocampus in middle-aged ovariectomized female rats as well as middle-aged control female and male rats to identify any correlation between calcium and phytoestrogens. In the CA1 region, CB immunoreactivity in the ovariectomized females was similar to that of the control females, whereas CB immunoreactivity in the males was significantly lower than that of the control females. In the dentate gyrus, CB immunoreactivity in the ovariectomized females and males was significantly lower than that of the control females. CB immunoreactivity in all groups was increased dose-dependently after ISO treatment in the CA1 region and dentate gyrus. This result suggests that ISO treatment enhances the expression of CB immunoreactivity in the hippocampus in the middle-aged rats.
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Affiliation(s)
- In Koo Hwang
- Department of Anatomy College of Medicine, Hallym University, Chunchon, South Korea
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74
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Mamiya T, Asanuma T, Kawai Y, Hasegawa Y, Nishimura A, Kumazawa T, Ukai M. Effects of soybean food pellets on m-CPP-induced anxiety model of mice. Biol Pharm Bull 2006; 29:1498-500. [PMID: 16819198 DOI: 10.1248/bpb.29.1498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, we gave the soybean powder-added food pellets (soybean pellets) to investigate anti-anxious effects of soybean in male mice. Twenty eight days after feeding control pellets or soybean pellets, we observed the behavioral changes in the elevated plus maze. There was no significant difference on the time spent in the open arms (%) between mice fed the control and soybean pellets. When we administered m-chlorophenylpiperazine (m-CPP, 2.5 mg/kg, i.p.) to mice, the mice fed control pellets showed the decrease in the time spent in the open arms, suggesting that anxiety-like behavior was induced by m-CPP. On the other hand, we could not observe the m-CPP-induced anxiety-like behavior in mice fed soybean pellets in this test. These results suggest that soybean pellets may attenuate anxiety-like behavior in mice.
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Affiliation(s)
- Takayoshi Mamiya
- Department of Chemical Pharmacology, Faculty of Pharmacy, Meijo University, Nagoya, Japan.
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75
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Gulinello M, Lebesgue D, Jover-Mengual T, Zukin RS, Etgen AM. Acute and chronic estradiol treatments reduce memory deficits induced by transient global ischemia in female rats. Horm Behav 2006; 49:246-60. [PMID: 16125703 PMCID: PMC4169120 DOI: 10.1016/j.yhbeh.2005.07.010] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Revised: 07/01/2005] [Accepted: 07/15/2005] [Indexed: 11/28/2022]
Abstract
Transient global ischemia induces selective, delayed neuronal death in the hippocampal CA1 and delayed cognitive deficits. Estrogen treatment ameliorates hippocampal injury associated with global ischemia. Although much is known about the impact of estrogen on neuronal survival, relatively little is known about its impact on functional outcome assessed behaviorally. We investigated whether long-term estradiol (21-day pellets implanted 14 days prior to ischemia) or acute estradiol (50 microg infused into the lateral ventricles immediately after ischemia) attenuates ischemia-induced cell loss and improves visual and spatial working memory in ovariectomized female rats. Global ischemia significantly impaired visual and spatial memory, assessed by object recognition and object placement tests at 6-9 days. Global ischemia did not affect locomotion, exploration, or anxiety-related behaviors, assessed by an open-field test at 6 days. Long-term estradiol prevented the ischemia-induced deficit in visual working memory, maintaining normal performance in tests with retention intervals of up to 1 h. Long-term estradiol also prevented ischemia-induced deficits in spatial memory tests with short (1 and 7 min), but not longer (15 min), retention intervals. Acute estradiol significantly improved visual memory assessed with short retention intervals, but did not prevent deficits in spatial memory. Acute estradiol significantly increased the number of surviving CA1 neurons, assessed either at 7 days after ischemia or after the completion of behavioral testing 9 days after ischemia. In contrast, chronic estradiol did not reduce CA1 cell death 9 days after ischemia. Thus, long-term estradiol at near physiological levels and acute estradiol administered after ischemic insult improve functional recovery after global ischemia. These findings have important implications for intervention in the neurological sequellae associated with global ischemia.
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Affiliation(s)
- Maria Gulinello
- Albert Einstein College of Medicine, Department of Neuroscience, 1300 Morris Park Avenue, Room F113, Bronx, NY 10461, USA.
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76
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Azcoitia I, Moreno A, Carrero P, Palacios S, Garcia-Segura LM. Neuroprotective effects of soy phytoestrogens in the rat brain. Gynecol Endocrinol 2006; 22:63-9. [PMID: 16603429 DOI: 10.1080/09513590500519161] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Soy extracts are widely used as an alternative to hormone replacement therapy for the treatment of menopausal symptoms. Soy phytoestrogens, such as genistein, may act on the nervous system, affecting mood, cognitive function and behavior. In addition, several studies suggest that soy phytoestrogens are neuroprotective. The hypothesis of the present study was that soy extracts may exert neuroprotection and that this effect is mediated by phytoestrogens such as genistein. To test this hypothesis we assessed whether an acute administration of soy extract or genistein in vivo affects hippocampal neuronal loss induced by the systemic administration of kainic acid to adult Wistar female rats. One week after ovariectomy, animals received one intraperitoneal injection of soy extract (0.2, 1, 2 or 20 mg/kg), one injection of genistein (0.1, 1 or 10 mg/kg) or one injection of vehicle. Thirty minutes later, all animals received one intraperitoneal injection of kainic acid (7 mg/kg) or vehicle. One week after the injections, all animals were fixed by perfusion and the number of Nissl-stained neurons in the hilus of the dentate gyrus was estimated by the optical disector method. Administration of soy extract, even at high doses, did not induce neuronal loss and did not increase neuronal degeneration after kainic acid injury. On the contrary, soy extract at doses ranging from 1 to 20 mg/kg prevented neuronal loss induced by kainic acid. Genistein showed neuroprotective effects only at high dose (10 mg/kg), suggesting that other components in the soy extract are involved in the neuroprotective effect.
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Affiliation(s)
- Iñigo Azcoitia
- Departamento de Biología Celular, Facultad de Biología, Universidad Complutense, Madrid, Spain
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77
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Hwang IK, Lee YB, Yoo KY, Kang TC, Lim SS, Kim SM, Sohn HS, Kim WJ, Shin HK, Won MH. Soybean isoflavones alter parvalbumin in hippocampus of mid-aged normal female, ovariectomized female, and normal male rats. Acta Pharmacol Sin 2006; 27:59-65. [PMID: 16364211 DOI: 10.1111/j.1745-7254.2006.00258.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
AIM To investigate the long-term effect of soybean isoflavones on changes in parvalbumin (PV) immunoreactivity in the hippocampus in normal female, ovariectomized (OVX) female and normal male rats. METHODS Ten-month-old rats were assigned to one of 9 groups (n = 7 in each group) based on body weight using a randomized complete-block design. The groups were: control diet-treated females, OVX females, and males; 0.3 g/kg isoflavone-treated females, OVX females, and males; and 1.2 g/kg isoflavone-treated females, OVX females, and males. The PV immunostaining was conducted by using the standard avidin-biotin complex method. RESULTS PV immunoreactivity and the number of PV-immunoreactive neurons in all the groups after isoflavone treatment were significantly changed in the hippocampal CA1 region and in the dentate gyrus, but not in the hippocampal CA2/3 region. PV immunoreactivity and the number of PV-immunoreactive neurons in the control diet OVX females were similar to those in the control diet, and were greater than those in the control diet normal females. PV immunoreactivity and the number of PV-immunoreactive neurons in all the isoflavone-treated groups decreased dose-dependently after isoflavone treatment. CONCLUSION Long-term administration of isoflavones may induce a reduction of PV in interneurons in the hippocampal CA1 region and in the dentate gyrus. The reduction of PV in these regions suggests that the long-term administration of isoflavones may cause a change in calcium homeostasis in the hippocampal CA1 region and in the dentate gyrus.
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Affiliation(s)
- In-koo Hwang
- Department of Anatomy, College of Medicine, Hallym University, Chunchon, Korea
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78
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Lee YB, Lee HJ, Sohn HS. Soy isoflavones and cognitive function. J Nutr Biochem 2005; 16:641-9. [PMID: 16169201 DOI: 10.1016/j.jnutbio.2005.06.010] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2005] [Revised: 06/22/2005] [Accepted: 06/27/2005] [Indexed: 10/25/2022]
Abstract
There is growing interest in the physiological functions of soy isoflavones, especially in whether they affect cognitive function and have beneficial effects on neurodegenerative diseases. Here we review the recent evidence from clinical and experimental studies supporting a role for soy isoflavones in cognitive function. Soy isoflavones may mimic the actions and functions of estrogens on brain, and they have been shown to have positive effects on the cognitive function in females; however, studies on their effects on spatial memory have not provided consistent results in males. Although data from humans, cultures, and animal models are currently insufficient for elucidating the metabolism of soy isoflavone actions on cognitive function and the nervous system, we suggest two putative pathways; (1) an estrogen receptor-mediated pathway and (2) via the inhibition of tyrosine kinase, in particular by genistein, which is one of the soy isoflavones. Although soy isoflavones appear to have a positive effect on brain function, further research is needed to determine not only the efficacy but also the safety of soy isoflavones on the nervous system and cognitive function.
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Affiliation(s)
- Yoon-Bok Lee
- Central Research Institute, Dr Chung's Food Co., Ltd., Chungjoo-si, South Korea
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79
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Gutierrez-Zepeda A, Santell R, Wu Z, Brown M, Wu Y, Khan I, Link CD, Zhao B, Luo Y. Soy isoflavone glycitein protects against beta amyloid-induced toxicity and oxidative stress in transgenic Caenorhabditis elegans. BMC Neurosci 2005; 6:54. [PMID: 16122394 PMCID: PMC1215487 DOI: 10.1186/1471-2202-6-54] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Accepted: 08/25/2005] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Epidemiological studies have associated estrogen replacement therapy with a lower risk of developing Alzheimer's disease, but a higher risk of developing breast cancer and certain cardiovascular disorders. The neuroprotective effect of estrogen prompted us to determine potential therapeutic impact of soy-derived estrogenic compounds. Transgenic C. elegans, that express human beta amyloid (Abeta), were fed with soy derived isoflavones genistein, daidzein and glycitein (100 microg/ml) and then examined for Abeta-induced paralysis and the levels of reactive oxygen species. RESULTS Among the three compounds tested, only glycitein alleviated Abeta expression-induced paralysis in the transgenic C. elegans. This activity of glycitein correlated with a reduced level of hydrogen peroxide in the transgenic C. elegans. In vitro scavenging effects of glycitein on three types of reactive oxygen species confirmed its antioxidant properties. Furthermore, the transgenic C. elegans fed with glycitein exhibited reduced formation of beta amyloid. CONCLUSION These findings suggest that a specific soy isoflavone glycitein may suppress Abeta toxicity through combined antioxidative activity and inhibition of Abeta deposition, thus may have therapeutic potential for prevention of Abeta associated neurodegenerative disorders.
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Affiliation(s)
- Astrid Gutierrez-Zepeda
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Ross Santell
- Department of Human Sciences, Alcorn State University, Alcorn, MS 39096, USA
| | - Zhixin Wu
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Marishka Brown
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - YanJue Wu
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Ikhlas Khan
- National Center for Natural Products Research, School of Pharmacy, Oxford, MS 38655, USA
| | - Christopher D Link
- Institute for Behavioral Genetic, University of Colorado, Boulder CO 80309, USA
| | - Baolu Zhao
- Laboratory of Visual Information Processing, Center of Brain & Cognitive Science, Institute of Biophysics, Academia Sinica, Beijing 100101, P.R. China
| | - Yuan Luo
- Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
- Department of Pharmaceutical Science, School of Pharmacy, University of Maryland, Baltimore, MD 21201-1180, USA
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80
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Lephart ED, Setchell KDR, Handa RJ, Lund TD. Behavioral effects of endocrine-disrupting substances: phytoestrogens. ILAR J 2005; 45:443-54. [PMID: 15454683 DOI: 10.1093/ilar.45.4.443] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A major source of endocrine-disrupting substances, usually not considered in laboratory animal experiments, is the diet used in research investigations. Soy represents the main protein source in almost all natural-ingredient commercially available formulated diets. Soy-derived isoflavones are the most abundant and in many ways the most studied phytoestrogens, and phytoestrogens (isoflavones) are known endocrine disruptors. Research is reviewed that identifies the physiological and behavioral endocrine-disrupting effects of dietary phytoestrogens (isoflavones) in animal diets, including most of the isoflavones, which are in a glycoside form and biologically inactive, and those in the gastrointestinal tract, which are biologically active. The isoflavones genistein and daidzein have similar molecular weights and structural characteristics to that of 17-beta estradiol, which may enable them to exert estrogenic and antiestrogenic properties are described and characterized. Daidzein can be further metabolized to the potent and abundant molecule equol, which in rodents is produced in very large amounts and represents the major circulating metabolite among all biologically active isoflavones. Equol has the unique and important ability to specifically bind 5 alpha-dihydro-testosterone, and to act in turn to inhibit the action of this potent androgen. The specific influence of dietary soy phytoestrogens on consumptive, learning and memory, and anxiety-related behaviors is identified. Regulatory behaviors such as food and water intake, adipose deposition and leptin, and insulin levels affected by dietary isoflavones are also discussed.
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Affiliation(s)
- Edwin D Lephart
- Department of Physiology and Developmental Biology, Neuroscience Center, Brigham Young University, Provo, UT, USA
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81
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Schreihofer DA, Do KD, Schreihofer AM. High-soy diet decreases infarct size after permanent middle cerebral artery occlusion in female rats. Am J Physiol Regul Integr Comp Physiol 2005; 289:R103-8. [PMID: 15956759 DOI: 10.1152/ajpregu.00642.2004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Estrogen is a powerful neuroprotective agent in rodent models of ischemic stroke. However, in humans, estrogen treatment can increase risk of stroke. Health risks associated with hormone replacement have led many women to consider alternative therapies including high-soy diets or supplements containing soy isoflavones, which act as estrogen receptor ligands to selectively mimic some of estrogen's actions. We hypothesized that a high-soy diet would share the neuroprotective actions of estrogen in focal cerebral ischemia. Female Sprague-Dawley rats were ovariectomized and divided into three groups: isoflavone-free diet + placebo (IF-P), isoflavone-free diet + estradiol (IF-E), or high-soy diet + placebo (S-P). Two weeks after being placed on diets, rats underwent left permanent middle cerebral artery occlusion (MCAO). Reductions in ipsilateral cerebral blood flow were equivalent across groups ( approximately 50%). Twenty-four hours later neurological deficit was determined, and brains were collected for assay of cerebral infarct by TTC staining. In the IF-P rats MCAO produced a 50 +/- 4% cerebral infarct. Estrogen and high-soy diet both significantly reduced the size of the infarcts to 26 +/- 5% in IF-E rats and to 37 +/- 5% in S-P rats. Analysis at five rostro-caudal levels revealed that estrogen treatment was slightly more effective at reducing infarct size than high soy diet. Overall neurological deficit scores at 24 h correlated with infarct size; however, there were no statistically significant differences among the treatment groups. These data show that 2 wk of a high-soy diet is an effective prophylactic strategy for reducing stroke size in a rat model of focal cerebral ischemia.
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Affiliation(s)
- Derek A Schreihofer
- Department of Physiology, 1120 15th St., CA-3145, Medical College of Georgia, Augusta, GA 30912-3000, USA.
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82
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Schreihofer DA. Transcriptional regulation by phytoestrogens in neuronal cell lines. Mol Cell Endocrinol 2005; 231:13-22. [PMID: 15713532 DOI: 10.1016/j.mce.2004.12.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 12/14/2004] [Accepted: 12/16/2004] [Indexed: 10/25/2022]
Abstract
Widespread epidemiological data support the notion that high isoflavone intake is safe and may provide health benefits similar to estrogen. Evidence from rodents shows that certain phytoestrogens can act as estrogen receptor (ER) ligands in the brain. This study sought to determine the estrogenic profile of food-borne phytoestrogens in neuronal cell lines using physiologically attainable concentrations. At sub-micromolar concentrations genistein, daidzein, and zearalenone stimulated ERalpha and ERbeta-dependent transcription in Neuro2A cells co-transfected with ERs and simple and complex estrogen-response-element (ERE) containing promoters, although compounds were more active in the presence of ERbeta. In SN56, neuronblastoma cells expressing endogenous ERs, only genistein mimicked estrogen regulation of progesterone receptor steady state mRNA levels. Unlike pharmaceutical SERMs, phytoestrogens did not stimulate an AP-1-dependent promoter. Micromolar concentrations of phytoestrogens did not antagonize physiological estrogen concentrations or antagonist activation of an AP-1-dependent promoter. These results demonstrate that food-borne phytoestrogens, particularly those found in soy, act as ERE-, but not AP-1-dependent transcriptional activators in neurons in the absence of estrogen, and dietary levels of these compounds do not act as antagonists to physiological estrogen concentrations.
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Affiliation(s)
- Derek A Schreihofer
- Department of Physiology, Medical College of Georgia, 1120 15th Street, CL2130, Augusta, GA 30912-3000, USA.
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83
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Abstract
Because of their protective effects in age-related diseases and hormone-dependent cancers, the use of phytoestrogens (isoflavones) as 'natural' remedies has gained prominence. Isoflavones are estrogen mimics that bind estrogen receptors and act like natural selective estrogen receptors modulators. However, limited data exists regarding the influence of soy-derived dietary isoflavones in brain. This brief review will address these topics and examine the influence of dietary isoflavones on sexually dimorphic hypothalamic nuclei. We have observed that altering the isoflavone content within diet significantly affects both the sexually dimorphic nucleus of the preoptic area (a structure that is larger in males than in females) and the anteroventral periventricular nucleus (a structure that is larger in females than in males). Specifically, when animals were switched from phytoestrogen-rich to a phytoestrogen-free diet the volume of the sexually dimorphic nucleus of the preoptic area was decreased in males (no alterations were detected in females). Conversely, when the anteroventral periventricular nucleus was examined, volume changes were recorded in males and females opposite to the patterns observed for the sexually dimorphic nucleus of the preoptic area. Given the practical limitations of examining the effects of dietary phytoestrogens in the human brain, it is important to establish comparative data sets to elucidate phytoestrogen's hormone action and potentially its beneficial brain health effects.
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Affiliation(s)
- Edwin D Lephart
- The Neuroscience Center, Brigham Young University, 633 WIDB, Provo, UT 84602, USA
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84
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Lephart ED, Porter JP, Lund TD, Bu L, Setchell KDR, Ramoz G, Crowley WR. Dietary isoflavones alter regulatory behaviors, metabolic hormones and neuroendocrine function in Long-Evans male rats. Nutr Metab (Lond) 2004; 1:16. [PMID: 15617573 PMCID: PMC544860 DOI: 10.1186/1743-7075-1-16] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Accepted: 12/23/2004] [Indexed: 01/27/2023] Open
Abstract
Background Phytoestrogens derived from soy foods (or isoflavones) have received prevalent usage due to their 'health benefits' of decreasing: a) age-related diseases, b) hormone-dependent cancers and c) postmenopausal symptoms. However, little is known about the influence of dietary phytoestrogens on regulatory behaviors, such as food and water intake, metabolic hormones and neuroendocrine parameters. This study examined important hormonal and metabolic health issues by testing the hypotheses that dietary soy-derived isoflavones influence: 1) body weight and adipose deposition, 2) food and water intake, 3) metabolic hormones (i.e., leptin, insulin, T3 and glucose levels), 4) brain neuropeptide Y (NPY) levels, 5) heat production [in brown adipose tissue (BAT) quantifying uncoupling protein (UCP-1) mRNA levels] and 6) core body temperature. Methods This was accomplished by conducting longitudinal studies where male Long-Evans rats were exposed (from conception to time of testing or tissue collection) to a diet rich in isoflavones (at 600 micrograms/gram of diet or 600 ppm) vs. a diet low in isoflavones (at approximately 10–15 micrograms/gram of diet or 10–15 ppm). Body, white adipose tissue and food intake were measured in grams and water intake in milliliters. The hormones (leptin, insulin, T3, glucose and NPY) were quantified by radioimmunoassays (RIA). BAT UCP-1 mRNA levels were quantified by PCR and polyacrylamide gel electrophoresis while core body temperatures were recorded by radio telemetry. The data were tested by analysis of variance (ANOVA) (or where appropriate by repeated measures). Results Body and adipose tissue weights were decreased in Phyto-600 vs. Phyto-free fed rats. Food and water intake was greater in Phyto-600 animals, that displayed higher hypothalamic (NPY) concentrations, but lower plasma leptin and insulin levels, vs. Phyto-free fed males. Higher thyroid levels (and a tendency for higher glucose levels) and increased uncoupling protein (UCP-1) mRNA levels in brown adipose tissue (BAT) were seen in Phyto-600 fed males. However, decreased core body temperature was recorded in these same animals compared to Phyto-free fed animals. Conclusions This study demonstrates that consumption of a soy-based (isoflavone-rich) diet, significantly alters several parameters involved in maintaining body homeostatic balance, energy expenditure, feeding behavior, hormonal, metabolic and neuroendocrine function in male rats.
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Affiliation(s)
- Edwin D Lephart
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, USA
- The Neuroscience Center, Brigham Young University, Provo, UT, USA
| | - James P Porter
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, USA
- The Neuroscience Center, Brigham Young University, Provo, UT, USA
| | - Trent D Lund
- Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Lihong Bu
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, USA
- The Neuroscience Center, Brigham Young University, Provo, UT, USA
| | - Kenneth DR Setchell
- Department of Pediatrics, Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Gina Ramoz
- Pharmacology & Toxicology, University of Utah, College of Pharmacy, Salt Lake City, UT, USA
| | - William R Crowley
- Pharmacology & Toxicology, University of Utah, College of Pharmacy, Salt Lake City, UT, USA
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86
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Goddard IW. Soy-induced brain atrophy? ACTA ACUST UNITED AC 2004; 6:335-6. [PMID: 15142435 DOI: 10.1089/109454503323028939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Epidemiological research has demonstrated a positive correlation between tofu consumption and brain atrophy in men. Because correlation does not prove causation, correlation-based hypotheses should be tested against the availability of possible causal mechanisms. While it has been shown that the soy phytoestrogen genistein inhibits neuroprotective functions in cell cultures, recent in-vivo findings strengthen the case for a possible causal mechanism of soy-induced neurodegeneration. The author suggests possible responses to this data regarding soy consumption.
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87
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Maggi A, Ciana P, Belcredito S, Vegeto E. Estrogens in the Nervous System: Mechanisms and Nonreproductive Functions. Annu Rev Physiol 2004; 66:291-313. [PMID: 14977405 DOI: 10.1146/annurev.physiol.66.032802.154945] [Citation(s) in RCA: 172] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The past decade has witnessed a growing interest in estrogens and their activity in the central nervous system, which was originally believed to be restricted to the control of reproduction. It is now well accepted that estrogens modulate the activity of all types of neural cells through a multiplicity of mechanisms. Estrogens, by binding to two cognate receptors ERalpha and ERbeta, may interact with selected promoters to initiate the synthesis of target proteins. Alternatively, the hormone receptor complex may interfere with intracellular signaling at both cytoplasmic and nuclear levels. The generation of cellular and animal models, combined with clinical and epidemiological studies, has allowed us to appreciate the neurotrophic and neuroprotective effects of estrogens. These findings are of major interest because estradiol might become an important therapeutic agent to maintain neural functions during aging and in selected neural diseases.
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Affiliation(s)
- Adriana Maggi
- University of Milan, Department of Pharmacological Sciences and Center of Excellence on Neurodegenerative Diseases, Via Balzaretti 920129 Milan, Italy.
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88
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Abstract
Current theories of number processing postulate that the human abilities for arithmetic are based on cerebral circuits that are partially laid down under genetic control and later modified by schooling and education. This view predicts the existence of genetic diseases that interfere specifically with components of the number system. Here, we investigate whether Turner syndrome (TS) corresponds to this definition. TS is a genetic disorder which affects one woman in 2500 and is characterized by partial or complete absence of one X chromosome. In addition to well-characterized physical and hormonal dysfunction, TS patients exhibit cognitive deficits including dyscalculia. We tested 12 women with Turner syndrome and 13 control subjects on a cognitive battery including arithmetical tests (addition, subtraction, multiplication, division) as well as tests of the understanding of numerosity and quantity (cognitive estimation, estimation, comparison, bisection, subitizing/counting). Impairments were observed in cognitive estimation, subitizing, and calculation. We examine whether these deficits can be attributed to a single source, and discuss the possible implications of hormonal and genetic factors in the neuropsychological profile of TS patients.
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Affiliation(s)
- Marie Bruandet
- INSERM Unit 562 Cognitive Neuroimaging, Service Hospitalier Frédéric Joliot, CEA/DRM/DSV, 4 Place du général Leclerc, 91401 Orsay Cedex, France
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89
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Lecanu L, Yao W, Teper GL, Yao ZX, Greeson J, Papadopoulos V. Identification of naturally occurring spirostenols preventing beta-amyloid-induced neurotoxicity. Steroids 2004; 69:1-16. [PMID: 14715372 DOI: 10.1016/j.steroids.2003.09.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
22R-Hydroxycholesterol is an intermediate in the steroid biosynthesis pathway shown to exhibit a neuroprotective property against beta-amyloid (1-42) (Abeta) toxicity in rat PCl2 and human NT2N neuronal cells by binding and inactivating Abeta. In search of potent 22R-hydroxycholesterol derivatives, we assessed the ability of a series of naturally occurring entities containing the 22R-hydroxycholesterol structure to protect PC12 cells against Abeta-induced neurotoxicity, determined by measuring changes in membrane potential, mitochondrial diaphorase activity, ATP levels and trypan blue uptake. 22R-Hydroxycholesterol derivatives sharing a common spirost-5-en-3-ol or a furost-5-en-3-ol structure were tested. Although some of these compounds were neuroprotective against 0.1 microM Abeta, only three protected against the 1-10 microM Abeta-induced toxicity and, in contrast to 22R-hydroxycholesterol, all were devoid of steroidogenic activity. These entities shared a common structural feature, a long chain ester in position 3 and common stereochemistry. The neuroprotective property of these compounds was coupled to their ability to displace radiolabeled 22R-hydroxycholesterol from Abeta, suggesting that the Abeta-22R-hydroxycholesterol physicochemical interaction contributes to their beneficial effect. In addition, a 22R-hydroxycholesterol derivative inhibited the formation of neurotoxic amyloid-derived diffusible ligands. Computational docking simulations of 22R-hydroxycholesterol and its derivatives on Abeta identified two binding sites. Chemical entities, as 22R-hydroxycholesterol, seem to bind preferentially only to one site. In contrast, the presence of the ester chain seems to confer the ability to bind to both sites on Abeta, leading to neuroprotection against high concentrations of Abeta. In conclusion, these results suggest that spirost-5-en-3-ol naturally occurring derivatives of 22R-hydroxycholesterol might offer a new approach for Alzheimer's disease therapy.
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Affiliation(s)
- Laurent Lecanu
- Department of Cell Biology, Georgetown University School of Medicine, Washington, DC 20057, USA
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90
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Mihalick SM. Perinatal exposure to diethylstilbestrol improves olfactory discrimination learning in male and female Swiss-Webster mice. Neurobiol Learn Mem 2003; 80:55-62. [PMID: 12737934 DOI: 10.1016/s1074-7427(03)00020-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
During late prenatal and early postnatal brain development, estrogen induces structural sex differences that correspond to behavioral differences in certain domains such as learning and memory. The typically superior performance of males is attributed to the action of elevated concentrations of estrogen, derived inside neurons from the aromatization of testosterone. In contrast, female performance appears dependent on minimal estrogenic activity. Rat models of the relationship between hormones and cognitive behavior predominate the field, but the advent of genetically modified mice as research tools necessitates development of analogous mouse models. This study examined how early postnatal exposure to the synthetic estrogen diethylstilbestrol (DES) affected the ability of male and female Swiss-Webster mice to learn a two-choice olfactory discrimination and three repeated reversals. Mice treated with subcutaneous injections of DES from postnatal days 1-10 learned reversals more readily than oil-treated controls, a difference that became evident after repeated testing. DES-exposed males and females learned reversals at a comparable rate, suggesting that early postnatal estrogen exposure does not influence this mode of learning through a sexually differentiated mechanism in mice. An analysis of response patterns during qualitatively different phases of reversal learning revealed that DES-induced improvements probably were not due to greater inhibitory control. Instead, DES appeared to enhance associative ability. Early postnatal estrogen exposure may have the potential to preserve certain cognitive skills in adulthood.
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Affiliation(s)
- Sheila M Mihalick
- Eunice Kennedy Shriver Center for Mental Retardation, University of Massachusetts Medical School, USA.
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91
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Duffy R, Wiseman H, File SE. Improved cognitive function in postmenopausal women after 12 weeks of consumption of a soya extract containing isoflavones. Pharmacol Biochem Behav 2003; 75:721-9. [PMID: 12895690 DOI: 10.1016/s0091-3057(03)00116-3] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
We previously reported that a high soya diet improved memory and frontal lobe function in young volunteers, and since soya isoflavones are agonists at oestrogen receptors, they may improve these functions in postmenopausal women. Thirty-three postmenopausal women (50-65 years) not receiving conventional hormone replacement therapy (HRT) were randomly allocated in a double-blind parallel study to receive a soya supplement (60 mg total isoflavone equivalents/day) or placebo for 12 weeks. They received a battery of cognitive tests and completed analogue rating scales of mood and sleepiness, and a menopausal symptoms questionnaire before the start of treatment and then after 12 weeks of treatment. Those receiving the isoflavone supplement showed significantly greater improvements in recall of pictures and in a sustained attention task. The groups did not differ in their ability to learn rules, but the isoflavone supplement group showed significantly greater improvements in learning rule reversals. They also showed significantly greater improvement in a planning task. There was no effect of treatment on menopausal symptoms, self-ratings of mood, bodily symptoms or sleepiness. Thus, significant cognitive improvements in postmenopausal women can be gained from 12 weeks of consumption of a supplement containing soya isoflavones that are independent of any changes in menopausal symptoms, mood or sleepiness.
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Affiliation(s)
- Rosanna Duffy
- Department of Nutrition and Dietetics, Nutrition, Food and Health Research Centre, Franklin-Wilkins Building, King's College London, London SE1 9NN, UK
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92
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Lephart ED, Rhees RW, Setchell KDR, Bu LH, Lund TD. Estrogens and phytoestrogens: brain plasticity of sexually dimorphic brain volumes. J Steroid Biochem Mol Biol 2003; 85:299-309. [PMID: 12943716 DOI: 10.1016/s0960-0760(03)00210-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Sexually dimorphic brain volumes (sexually dimorphic nucleus of the preoptic area (SDN-POA) and anteroventral periventricular (AVPV) nucleus) are influenced by estrogens. Phytoestrogens, derived from plants (especially soy products), are molecules structurally and functionally similar to estradiol. The purpose of this study was to examine: the consumption of phytoestrogen (using a phytoestrogen-rich (Phyto-600) versus a phytoestrogen-free (Phyto-free)) diets from conception to adulthood (or changing the diets during adulthood) and characterizing (a) circulating plasma phytoestrogen levels, (b) testosterone levels in males, (c) sexually dimorphic brain volumes (i.e. the SDN-POA and AVPV) and (d) the presence of apoptotic cells in these brain structures in Long-Evans rats. Phyto-600 fed animals displayed total serum phytoestrogens levels 37-fold higher compared to Phyto-free values. Circulating testosterone levels were not significantly altered by the diets. Female SDN-POA volumes were not altered by the diets. Whereas, males fed a Phyto-free diet displayed decreased SDN-POA volumes compared to male Phyto-600 values. Females fed the Phyto-600 diet displayed larger AVPV volumes compared to males on the same diet or females on the Phyto-free diet. Males fed the Phyto-free diet had the largest AVPV values compared to Phyto-600 fed males. When the SDN-POA region was examined in lifelong Phyto-free fed males, apoptotic cells were present versus males fed the Phyto-600 diet and in the AVPV region the opposite results were obtained. In summary, consumption of dietary phytoestrogens (estrogen mimics) can alter hormone-sensitive hypothalamic brain volumes in rodents during adulthood.
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Affiliation(s)
- E D Lephart
- The Neuroscience Center, 633 WIDB, Brigham Young University, Provo, UT 84602, USA.
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Lephart ED, Galindo E, Bu LH. Stress (hypothalamic-pituitary-adrenal axis) and pain response in male rats exposed lifelong to high vs. low phytoestrogen diets. Neurosci Lett 2003; 342:65-8. [PMID: 12727319 DOI: 10.1016/s0304-3940(03)00262-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
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.
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Affiliation(s)
- Edwin D Lephart
- The Neuroscience Center and Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602, USA.
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Hartley DE, Edwards JE, Spiller CE, Alom N, Tucci S, Seth P, Forsling ML, File SE. The soya isoflavone content of rat diet can increase anxiety and stress hormone release in the male rat. Psychopharmacology (Berl) 2003; 167:46-53. [PMID: 12618915 DOI: 10.1007/s00213-002-1369-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2002] [Accepted: 11/25/2002] [Indexed: 10/20/2022]
Abstract
RATIONALE Most commercial rodent diets are formulated with soya protein and therefore contain soya isoflavones. Isoflavones form one of the main classes of phytoestrogens and have been found to exert both oestrogenic and anti-oestrogenic effects on the central nervous system. The effects have not been limited to reproductive behaviour, but include effects on learning and anxiety and actions on the hypothalamo-pituitary axis. It is therefore possible that the soya content of diet could have significant effects on brain and behaviour and be an important source of between-laboratory variability. OBJECTIVES To determine whether behaviour in two animal tests of anxiety, and stress hormone production, would differ between rats that were fed a diet which was free of soya isoflavones and other phytoestrogens (iso-free) and those that were fed a diet which contained 150 microg/g of the isoflavones genistein and daidzein (iso-150). This controlled diet has an isoflavone concentration similar to that in the maintenance diet routinely used in our institution. METHODS Male rats were randomly allocated to the iso-free and iso-150 diets and their body weights and food and water consumption were recorded for 14 days. They were then maintained on the same diets, but housed singly for 4 days, before testing in the social interaction and elevated plus-maze tests of anxiety. Corticosterone concentrations in both dietary groups were determined under basal conditions and after the stress of the two tests of anxiety. Vasopressin and oxytocin concentrations were determined after brief handling stress. RESULTS The groups did not differ in food or water intake, body weight or oxytocin concentrations. Compared with the rats fed the iso-free diet, the rats fed the iso-150 diet spent significantly less time in active social interaction and made a significantly lower percentage of entries onto the open arms of the plus-maze, indicating anxiogenic effects in both animal tests. The groups did not differ in their basal corticosterone concentrations, but the iso-150 group had significantly elevated stress-induced corticosterone concentrations. Stress-induced plasma vasopressin concentrations were also significantly elevated in the iso-150 diet group compared with the iso-free rats. CONCLUSIONS Major changes in behavioural measures of anxiety and in stress hormones can result from the soya isoflavone content of rat diet. These changes are as striking as those seen following drug administration and could form an important source of variation between laboratories.
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Affiliation(s)
- David E Hartley
- Psychopharmacology Research Unit, Centre for Neuroscience, Hodgkin Building, Kings College London, Guy's Campus, SE1 1UL, London, UK.
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Lund TD, Fleming DE, Dayton JR, Lephart ED, Salyer DL. Dietary soy phytoestrogens effects on retinal thickness in rats. Nutr Neurosci 2003; 6:47-51. [PMID: 12608736 DOI: 10.1080/1028415021000056050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Naturally occurring estrogen-like molecules in plants (phytoestrogens), present via soy, in animal diets are known to alter brain morphology and reproductive endocrine parameters. This study characterized dietary phytoestrogens' effect on retinal thickness in male and female Long-Evans rats. Experiment 1a and 1b: upon arrival (50 day-old) animals received either a phytoestrogen-rich diet (containing 600 microg phytoestrogen/g diet; referred to as Phyto-600) or a diet low in phytoestrogens (Phyto-free). Males remained on these diets until 140 days of age (females until 160 days of age). In both sexes a significant (but opposite) diet difference in retinal thickness was identified. Male Phyto-600 and female Phyto-free animals had significantly greater retinal thickness compared to Phyto-free males and Phyto-600 females, respectively. Experiment 2: male or female rats were raised from conception on either the Phyto-600 or Phyto-free diet until sacrifice at 75 days of age. Consistent with experiment 1, males exposed to the Phyto-600 diet lifelong had significantly greater retinal thickness than lifelong fed Phyto-free males (no significant differences were identified in females). These data suggest that phytoestrogens influence rat retinal characteristics in a sexually dimorphic manner (more robust effect in males vs. females) and that this influence can occur even in adulthood.
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Affiliation(s)
- Trent D Lund
- 633 WIDB, The Neuroscience Center, Brigham Young University, Provo, UT 84602, USA
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Chemistry and Biological Activities of Isoprenylated Flavonoids from Medicinal Plants (Moraceous Plants and Glycyrrhiza Species). BIOACTIVE NATURAL PRODUCTS (PART I) 2003. [DOI: 10.1016/s1572-5995(03)80142-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Lephart ED, West TW, Weber KS, Rhees RW, Setchell KDR, Adlercreutz H, Lund TD. Neurobehavioral effects of dietary soy phytoestrogens. Neurotoxicol Teratol 2002; 24:5-16. [PMID: 11836067 DOI: 10.1016/s0892-0362(01)00197-0] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
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.
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Affiliation(s)
- Edwin D Lephart
- Neuroscience Center, 633 WIDB, Brigham Young University, Provo, UT 86402, USA.
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