Comparison of the estrogenic potencies of standardized soy extracts by immature rat uterotrophic bioassay

Vieira, Manuela de Lima Toccafondo; Duarte, Rodrigo Ferreira; Campos, Lígia Maria Moreira de; Nunan, Elzíria de Aguiar

doi:10.1016/j.phymed.2007.06.006

Cited by 17 publications

(14 citation statements)

References 33 publications

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“…The immature rat uterotrophic assay was performed according to methods previously described by Kanno et al [82] and de Lima et al [83]. Immature Wistar rats (21 days) were randomly assigned to groups (n=10) and treated daily with E 2 , genistein, Cyclopia extracts, or vehicle control (sterile PBS) by oral gavage for three consecutive days.…”

Section: Methodsmentioning

confidence: 99%

Cyclopia Extracts Act as ERα Antagonists and ERβ Agonists, In Vitro and In Vivo

2013

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Hormone replacement therapy associated risks, and the concomitant reluctance of usage, has instigated the search for new generations of estrogen analogues that would maintain estrogen benefits without associated risks. Furthermore, if these analogues display chemo-preventative properties in breast and endometrial tissues it would be of great value. Both the selective estrogen receptor modulators as well as the selective estrogen receptor subtype modulators have been proposed as estrogen analogues with improved risk profiles. Phytoestrogen containing extracts of Cyclopia, an indigenous South African fynbos plant used to prepare Honeybush tea may serve as a source of new estrogen analogues. In this study three extracts, P104, SM6Met, and cup-of-tea, from two species of Cyclopia, C. genistoides and C. subternata, were evaluated for ER subtype specific agonism and antagonism both in transactivation and transrepression. For transactivation, the Cyclopia extracts displayed ERα antagonism and ERβ agonism when ER subtypes were expressed separately, however, when co-expressed only agonism was uniformly observed. In contrast, for transrepression, this uniform behavior was lost, with some extracts (P104) displaying uniform agonism, while others (SM6Met) displayed antagonism when subtypes were expressed separately and agonism when co-expressed. In addition, breast cancer cell proliferation assays indicate that extracts antagonize cell proliferation in the presence of estrogen at lower concentrations than that required for proliferation. Furthermore, lack of uterine growth and delayed vaginal opening in an immature rat uterotrophic model validates the ERα antagonism of extracts observed in vitro and supports the potential of the Cyclopia extracts as a source of estrogen analogues with a reduced risk profile.

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Section: Methodsmentioning

confidence: 99%

Cyclopia Extracts Act as ERα Antagonists and ERβ Agonists, In Vitro and In Vivo

2013

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“…We chose isoflavone‐free soy protein as the comparable protein source, as it is a non‐milk based protein source and is widely used in maintaining health body weight. In addition, we used isoflavone‐free soy protein to eliminate the potential effects of estrogenic activity of soy (20) on food intake (21). Our results demonstrate that a high‐protein diet (38% protein content) using either whey or isoflavone‐free soy protein reduces body weight gain, body fat and N‐free RQ in rats compared to the control diet.…”

Section: Discussionmentioning

confidence: 99%

Dietary Whey Protein Decreases Food Intake and Body Fat in Rats

Zhou

Keenan

Losso

et al. 2011

Obesity

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We investigated the effects of dietary whey protein on food intake, body fat, and body weight gain in rats. Adult (11–12 week) male Sprague–Dawley rats were divided into three dietary treatment groups for a 10-week study: control. Whey protein (HP-W), or high-protein content control (HP-S). Albumin was used as the basic protein source for all three diets. HP-W and HP-S diets contained an additional 24% (wt/wt) whey or isoflavone-free soy protein, respectively. Food intake, body weight, body fat, respiratory quotient (RQ), plasma cholecystokinin (CCK), glucagon like peptide-1 (GLP-1), peptide YY (PYY), and leptin were measured during and/or at the end of the study. The results showed that body fat and body weight gain were lower (P < 0.05) at the end of study in rats fed HP-W or HP-S vs. control diet. The cumulative food intake measured over the 10-week study period was lower in the HP-W vs. control and HP-S groups (P < 0.01). Further, HP-W fed rats exhibited lower N2 free RQ values than did control and HP-S groups (P < 0.01). Plasma concentrations of total GLP-1 were higher in HP-W and HP-S vs. control group (P < 0.05), whereas plasma CCK, PYY, and leptin did not differ among the three groups. In conclusion, although dietary HP-W and HP-S each decrease body fat accumulation and body weight gain, the mechanism(s) involved appear to be different. HP-S fed rats exhibit increased fat oxidation, whereas HP-W fed rats show decreased food intake and increased fat oxidation, which may contribute to the effects of whey protein on body fat.

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“…The Animal Research Committee of Hirosaki University approved this study (permission number: G15006), which was conducted in accordance with the rules for Animal Experimentation of Hirosaki University. The immature rat uterotrophic assay was performed according to previously described methods . At the age of 3 weeks, female SDRs ( n = 5–6 each) were gavaged once daily for a period of 3 days with E2 (100 μg/kg) or BCE (100 or 1,000 mg/kg).…”

Section: Methodsmentioning

confidence: 99%