Combinatorial effects of the phytoestrogen genistein and of estradiol in uterus and liver of female Wistar rats

The knowledge about safety of phytoestrogens on proliferative endpoints in the endometrium is rather limited, particularly when low amounts of estrogens are present like in postmenopausal women. Therefore, we now studied how genistein (GEN) exposure affects proliferative endpoints in the endometrium in estrogenized animals. We investigated the effects of GEN (10 mg/(kg day) BW) on uterine proliferation and on general uterine response markers in intact female rats and ovariectomized (OVX) female rats co-treated with different doses of estradiol (E2; 1 or 4 μg/(kg day) BW). In parallel we investigated generalized hepatic effects of GEN in this co-stimulatory protocol. In agreement to our previous results, GEN treatment of OVX animals for 3 days results in a faint stimulation of the uterine wet weight. In intact animals and in OVX animals co-treated with E2 no effects of GEN on uterine wet weight were detectable. GEN treatment did not affect the uterine epithelial height in intact animals but resulted in a decrease of the protein and mRNA expression of the proliferation marker PCNA. In OVX animals co-treated with E2, GEN antagonized the E2 stimulated increase of the uterine epithelial height and epithelial PCNA expression. Besides PCNA, GEN effects on the uterine mRNA expression of IGF-1, IGF-1R, Complement C3, estrogen receptor- (ER) and -β (ERβ), as well as progesterone receptor were investigated in intact and OVX co-treated animals. Overall there was a tendency in all combinatorial groups that GEN counteracts E2 function in uterine tissue. Surprisingly, while investigating estrogenic response markers in liver, we observed very strong effects of GEN on hepatic marker gene expression. GEN significantly down-regulated CaBP9K and IGFBP1 mRNA levels in intact animals. In OVX animals hepatic CABP9K and IGFBP1 mRNA levels were not affected by E2 treatment. GEN treatment, even in combination with E2, decreased the hepatic CaBP9K expression below the levels observed in untreated animals. Interestingly co-treatment of OVX rats with low dose E2 and GEN resulted in a significant increase of IGFBP1 mRNA expression. Summarising our results we conclude that (1) GEN treatment in the presence of E2 is safe regarding proliferative responses in the endometrium of adult animals; (2) the observation of differences of the GEN activity in intact and OVX/E2 substituted animals can be taken as a hint that GEN may interact mechanistically with progestins which has to be proven in detail in future investigations and (3) the detection of strong effects of the phytoestrogen GEN on hepatic gene expression may point to the need of future investigations to rule out the possibility of adverse responses in this organ.     

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

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

Anti-estrogenic suppression of the lordosis response in female rats

The anti-estrogen, CI 628, was used to suppress the lordosis response induced by sequential injections of estrogen and progesterone in ovariectomized (OVX) female rats. Appropriate doses of CI 628 completely abolished sexual receptivity in females administered estradiol benzoate (EB) in sesame oil. This behavioral effect could be attenuated by providing increased quantities of EB or decreased quantities of CI 628. Anti-estrogenic effects on lordosis induced by free estradiol in saline (E) were assessed after first establishing behaviorally equivalent doses of EB and E. This was accomplished by determining thresholds for E-induced lordosis. OVX females were approximately seven times less sensitive to E than to EB. CI 628 had no significant effects on E-induced lordosis, in contrast to the complete abolition of lordosis in females treated with behaviorally equivalent EB doses. A possible mechanism to explain this differential responsiveness of EB- and E-treated females is discussed.     

Estrogenic effects of the ethyl-acetate extract of the stem bark of Erythrina lysistemon Hutch (Fabaceae)

The stem bark of Erythrina lysistemon, one of the traditionally used "women remedies", has been assessed for its estrogenic activity. The ethyl-acetate extract of the stem bark of E. lysistemon showed estrogenic activities in vitro either in a yeast-based estrogen receptor assay or on the estrogen-dependent stimulation of alkaline phosphatase activity in the human endometrial carcinoma cell line Ishikawa. The estrogenic activity was investigated in vivo in young ovariectomized Wistar female rats after a 7-day treatment. The estrogenicity was evaluated through the proliferative status of target sex organs such as uterus and vagina. The results obtained showed that oral administration of 200 mg/kg BW/d of E. lysistemon extract in comparison to untreated ovariectomized rats significantly increased the vaginal epithelial height by 47.23% (from 8.71+/-0.47 to 12.34+/-1.31 microm); and induced a weak increase of uterine epithelial height by 6.76% (from 5.42+/-0.52 to 5.84+/-0.91 microm). Both were not as pronounced as those elicited in the positive control of 100 microg/kg BW/d of ethinylestradiol given orally. Overall our results suggest that the extract of E. lysistemon contains secondary metabolites endowed with estrogenic activity.     

The selective estrogen receptor modulator SCH 57068 prevents bone loss, reduces serum cholesterol and blocks estrogen-induced uterine hypertrophy in ovariectomized rats

Our objective was to determine the effects of SCH 57068 alone and with 17 beta-estradiol (E(2)) on bone, lipids and uteri in ovariectomized (OVX) rats. In OVX animals lumbar vertebral and femoral bone mineral density (BMD) were significantly higher after 12 weeks of treatment with SCH 57068 than in untreated OVX controls. Similarly BMD was superior in OVX + E(2) + SCH 57068 treated animals than in OVX + E(2) controls. SCH 57068 also significantly reduced the increase in bone turnover markers, serum pyridinoline and serum osteocalcin levels, induced by OVX, and increased mechanical bone strength. SCH 57068 also significantly reduced the rise in serum cholesterol and low-density lipoprotein cholesterol induced by OVX. SCH 57068 had no stimulatory effect on uterine epithelium when given alone in OVX rats. SCH 57068 (1 and 2.5 mg/kg) reduced uterine weight and blocked endometrial stimulation induced by E(2). In summary, SCH 57068 adds to the positive effects of E(2) on bone and lipid metabolism but blocks the stimulatory effects of E(2) on the uterus. Potentially, E(2) + SCH 57068 could be combined for the treatment and prevention of breast cancer or as a novel hormone replacement therapy.     

Lowering effect of an isoflavone-rich fermented soybean extract on the serum cholesterol concentrations in female rats, with or without ovariectomy, but not in male rats

We examined the effect of administering an isoflavone-rich fermented soybean extract (FSBE) on the serum cholesterol concentrations in male rats and in intact and ovariectomized (OVX) female rats. Dietary FSBE decreased the serum cholesterol concentrations in intact female and OVX rats, but did not affect the concentrations in male rats. Dietary FSBE increased the hepatic total and esterified cholesterol contents in the intact female rats, but decreased them in the OVX rats. This hypocholesterolemic effect was not a simple estrogenic effect because it has appeared in some reports that estrogen administration decreased serum cholesterol both male and female rats. Dietary FSBE increased the hepatic low-density lipoprotein receptor (LDLR) gene expression in the intact female rats as has previously been reported from many studies, but did not affect that of the OVX rats. Further investigation is needed into the hypocholesterolemic mechanism of FSBE.     

Effects of dehydroepiandrosterone, Premarin and Acolbifene on histomorphology and sex steroid receptors in the rat vagina

To assess the specific estrogenic and/or androgenic effects of a potential novel hormone replacement therapy, we have examined the morphology of the rat vagina 9 months after ovariectomy (OVX) and treatment of OVX animals with dehydroepiandrosterone (DHEA), conjugated estrogens Premarin and the selective estrogen receptor modulator Acolbifene. OVX led to atrophy and inflammatory changes while Acolbifene reduced the inflammation incidence and induced mucification of the vaginal epithelium. Premarin induced a typical keratinized stratified squamous epithelium while DHEA induced stimulation of the vaginal epithelium, with mucous cells typical of an androgenic effect, combined with increased collagen fiber compactness of the lamina propria. On the other hand, after OVX, the vaginal muscle layer decreased by 46%, an effect which was 41 and 100% reversed by DHEA and Premarin, respectively. The present data show particularly interesting effects of DHEA on the three layers of the vaginal wall, namely a highly mucified epithelium, an increased muscularis thickness and increased collagen fiber compactness in the lamina propria. DHEA exerts both androgenic and estrogenic effects on the vaginal mucosa, thus providing a more physiological replacement therapy.     

Short term effects on bone quality associated with consumption of soy protein isolate and other dietary protein sources in rapidly growing female rats

Beneficial effects of soy protein consumption on bone quality have been reported. The effects of other dietary protein sources such as whey protein hydrolysate (WPH) and rice protein isolate (RPI) on bone growth have been less well examined. The current study compared effects of feeding soy protein isolate (SPI), WPH and RPI for 14 d on tibial bone mineral density (BMD) and bone mineral content (BMC) in intact and ovariectomized (OVX) rapidly growing female rats relative to animals fed casein (CAS). The effects of estrogenic status on responses to SPI were also explored. Tibial peripheral quantitative computerized tomography (pQCT) showed all three protein sources had positive effects on either BMD or BMC relative to CAS (P < 0.05), but SPI had greater effects in both intact and OVX female rats. SPI and E2 had positive effects on BMD and BMC in OVX rats (P < 0.05). However, trabecular BMD was lower in a SPI + E2 group compared to a CAS + E2 group. In OVX rats, SPI increased serum bone formation markers, and serum from SPI-fed rats stimulated osteoblastogenesis in ex vivo. SPI also suppressed the bone resorption marker RatLaps (P < 0.05). Both SPI and E2 increased alkaline phosphatase gene expression in bone, but only SPI decreased receptor activator of nuclear factor-kappaB ligand (RANKL) and estrogen receptor gene expression (P < 0.05). These data suggest beneficial bone effects of a soy diet in rapidly growing animals and the potential for early soy consumption to increase peak bone mass.     

Estrogenic effect on swelling and monocytic receptor expression in an arthritic temporomandibular joint model

Clinical presentation of temporomandibular joint (TMJ) disorders are more common in women and changes in the female hormone estrogen affect the level of swelling, pro-inflammatory cytokine release and pain in animal models of TMJ arthritis. Estrogen also modulates the expression of the CD16 receptor in vitro. This alters pro-inflammatory cytokine release in monocytes/macrophages when auto-antigens and arthritic factors bind the CD16 receptor. This study investigated the effects of various levels of estrogen on the intensity of inflammation and CD16 expression in a TMJ arthritic animal model. The experiments included rats that were intact or ovariectomized (OVX), eliminating the major source of estrogen output. A portion of the OVX animals had estrogen replaced with 17-beta estradiol (E2) using Alzet pumps. In OVX animals E2 levels were administered for 10 days to create an artificial estrus cycle or to simulate pregnancy. Following E2 treatment the rats were given an intra-articular TMJ injection of saline or complete Freund's adjuvant (CFA). CFA injection significantly increased TMJ swelling, stress induced chromodacryorrhea and attenuated food intake, thus indicating the adjuvant induced TMJ pain/inflammation. Removing endogenous E2 through OVX reduced CFA induced TMJ inflammation, whereas CFA increased the number of TMJ monocytes expressing the CD14 receptor equally in all groups irrespective of plasma E2 levels. Paradoxically, higher levels of E2 reduced the number of TNF-alpha positive, CD16+ and double labeled CD14+/CD16+ cells. The findings indicate that reduced plasma E2 levels attenuated CFA induced TMJ inflammation, whereas increasing E2 levels enhanced TMJ swelling in a dose dependent manner. Estrogenic group differences in CFA induced swelling were independent of TMJ CD14+, CD14+/CD16+ or CD16+ cell numbers suggesting E2 action on the CFA immune response primarily excluded CD16 receptor action.     

Effects of neonatal treatment with phytoestrogens, genistein and daidzein, on sex difference in female rat brain function: estrous cycle and lordosis

It is well known that neonatal exposure to estrogen induces masculinization or defeminization of the brain. In this study, the effects of neonatal treatment with two kinds of soybean isoflavone aglycone, genistein (GS) and daidzein (DZ), on the estrous cycle and lordosis behavior were investigated. Female rats were injected subcutaneously with 1 mg GS, 1 mg DZ, 100 microg estradiol (E2), or oil daily for 5 days from birth. As a result, vaginal opening was advanced in GS- or E2-treated females. A vaginal smear check indicated that oil- or DZ-treated females showed a constant 4- or 5-day estrous cycle, whereas GS- or E2-treated rats showed a persistent or prolonged estrus. Ovariectomy was performed in all females at 60 days of age. The ovaries in the GS- or E2-treated groups were smaller than those in the oil- and DZ-treated groups and contained no corpora lutea. In the DZ group, although corpora lutea were seen, ovaries were smaller than that of control females. Behavioral tests were carried out after implantation of E2-tubes. All of the oil- or DZ-treated females showed lordosis with a high lordosis quotient (LQ). On the other hand, as male rats, LQs were extremely low in the E2-treated group, when compared to the oil-treated group. In the GS-treated group, the mean LQ was lower than that in the oil-treated group, but higher than those in the E2-treated female or male groups. These results suggest that genistein acts as an estrogen in the sexual differentiation of the brain and causes defeminization of the brain in regulating lordosis and the estrous cycle in rats. In addition, neonatal daidzein also has some influence on ovarian function.     

Antioxidant effects of phyto-and synthetic-estrogens on cupric ion-induced oxidation of human low-density lipoproteins in vitro

Oxidation of low-density lipoproteins (LDL) promotes the formation of atherosclerotic plaques. Estrogenic compounds (EC) from foods and other natural products, and synthetic estrogenic compounds (SECs) may prevent heart disease by inhibiting LDL oxidation. In the present study, we tested the antioxidant capacities of two phytoestrogens, daidzein (DAI) and genistein (GEN), and four SECs, (+)- and (-)-Z-bisdehydrodoisynolic acid (ZBDDA), and (+)- and (-)-hydroxy-allenoic acid (HAA), on isolated human LDL subjected to oxidation by cupric sulfate. The effects of these estrogenic compounds on the kinetics of conjugated diene formation in LDL undergoing oxidation were evaluated with a lag-time assay with continuous monitoring of absorbance at 234 nm. Lag-time data revealed that (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA had similarly stronger antioxidant activities than either GEN or DAI. We also found that (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA strongly inhibited the formation of Cu+-induced thiobarbituric acid reactive substances (TBARS) in LDL, and that GEN and DAI were less effective for inhibiting LDL lipid peroxidation. Finally, electrophoretic evaluation suggested that (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA protected the apolipoprotein B-100 of LDL against oxidation better than did GEN or DAI. In summary, the four SECs, (+)-HAA, (-)-HAA, (+)-ZBDDA, and (-)-ZBDDA, were more potent antioxidants than the phytoestrogens, DAI and GEN.     

Genistein aglycone effect on bone loss is not enhanced by supplemental calcium and vitamin D3: A dose ranging experimental study

Genistein aglycone (GEN) has a favorable effect on bone loss. We investigated the effects of GEN alone or in combination with supplemental calcium and vitamin D₃ in an animal model of bone loss to evaluate if there was additional benefit. Ovariectomized (OVX) and SHAM-OVX rats were used. OVX were divided into 12 groups and randomized to receive: GEN at 27, 54, 200, 500 or 1000 mg (human equivalent dose (HED)/day/ip injection alone or with calcium carbonate (Ca) (360 mg/kg/day/gavages) and vitamin D₃ (D₃) (50 IU/kg/day/gavages) or Ca/D₃ without GEN or untreated for 6 weeks. SHAM-OVX were randomized into 7 groups and treated with: Ca and D₃ alone or in combination with GEN (same doses as OVX), or left untreated. Bone mineral density (BMD), bone-alkaline phosphatase (b-ALP), collagen C-telopeptides (CTX), osteoprotegerin (OPG) and soluble receptor activator of NFκB ligand (sRANKL) were assessed. Femurs were excised and tested for breaking strength and histology. Uterine weight was analyzed to assess GEN's estrogenic effects on the SHAM-OVX.The most effective dose of GEN, independent of Ca/D₃ supplementation, was 54 mg/day. Higher doses yielded no further improvement in bone biomarkers, histology or strength. Only 1000 mg/day HED of genistein produced statistically significant changes in uterine weight of the SHAM-OVX. This study suggests that 54 mg/day of GEN is the threshold dose for efficacy. In addition, supplemental calcium and vitamin D₃, beyond normal dietary intake do not enhance the effects of genistein on improving measures of bone loss. This observation has implications regarding the use of calcium and vitamin D₃ supplementation.     

Estrogenic and antifertility effect of cyproterone acetate in female gerbils, meriones hurriane Jerdon

Effects of cyproterone acetate, a steroidal synthetic compound, on the reproductive organs of female gerbils have been investigated. This agent causes reduction of ovarian weights indicative of suppression of pituitary gonadotrophins. Estrogenic nature of cyproterone acetate was investigated in intact and ovariectomized gerbils taking uterine weight, vaginal keratinization and glycogen contents are parameters of estrogenic action. Cyproterone acetate in ovariectomized gerbils induced vaginal keratinization, increase in uterine weight, protein, RNA, glycogen and sialic acid contents of uterus, thus indicating an estrogenic activity. The histological and biochemical parameters lead to the conclusion that cyproterone acetate possesses estrogenic properties.     

Effect of genistein on the expression of bone metabolism genes in ovariectomized mice using a cDNA microarray

Osteoporosis associated with estrogen deficiency is defined as an abnormal decrease in bone mass leading to an increased fracture risk. Genistein (GEN), as a phytoestrogen, is a type of soybean-derived isoflavone that possesses structural similarity to estrogen. In this study, we assessed the effect of GEN in ovariectomized (OVX) mice. To determine the effect of GEN on bone metabolism, we investigated gene expression profiles using a radioactive cDNA microarray. Eight-week-old female mice were either sham operated (SHAM) or OVX. From 1 week after the operation, OVX mice were injected daily with intraperitoneal GEN (0.1, 0.5, 1.5 and 3.0 mg/day) or 17beta-estradiol (E2, 0.03 microg/day) for 4 weeks. A cDNA microarray was used to evaluate changes in the expression of 1,152 genes. OVX mice showed bone mineral density (BMD) loss versus SHAM mice (5.8+/-0.4 vs. 6.9+/-0.6 mg/cm2). However, femur BMDs were completely restored by GEN and by E2 administration in OVX mice. Serum osteocalcin in OVX mice treated with 0.5 mg/day of GEN was 1.6-fold (44.30+/-5.73 ng/ml) higher than that in untreated mice. GEN treatment up-regulated 38 genes (e.g., mitogen-activated protein kinase 10) and down-regulated 18 (e.g., matrix metalloproteinase 13). Moreover, GEN was found to have a protective effect on bone loss caused by estrogen deficiency in OVX mice. The present study suggests that GEN modulates bone metabolism-related gene expression, including calciotropic receptor, cytokines, growth factors and bone matrix proteins.     

Estrogen rapidly modulates mustard oil-induced visceral hypersensitivity in conscious female rats: A role of CREB phosphorylation in spinal dorsal horn neurons

This study investigated the effect of sex hormones on mustard oil (MO)-induced visceral hypersensitivity in female rats and analyzed possible involved signaling pathways. Female rats, either intact or ovariectomized (OVX), were prepared for abdominal muscle electromyography in response to colorectal distension after intracolonic instillation of MO. The effect of MO intracolonic sensitization was evaluated in intact rats, OVX rats, and OVX rats pretreated with a single injection of 17beta-estradiol (E), progesterone (P), E+P, or vehicle. cAMP-responsive element-binding protein (CREB) and phosphorylated CREB (pCREB) were detected in the superficial dorsal horn of L6 and S1 in MO or mineral oil-treated OVX rats with/without colorectal distension and estrogen replacement. The distal colorectum was removed for histological evaluation of inflammatory severity in MO-treated intact or OVX rats. The MO-treated rats had significantly higher visceromotor reflex than controls (enhanced visceral hypersensitivity), whereas OVX eliminated this hypersensitivity. After a single injection of E or E+P, the rats rapidly restored MO-induced visceral hypersensitivity within 2 h. Estrogen also rapidly induced a dose-dependent increase in pCREB expression in the superficial dorsal horn neurons in MO-treated, but not mineral oil-treated, OVX rats. The present study suggests that estrogen can rapidly modulate visceral hypersensitivity induced by MO intracolonic instillation in conscious female rats, which may involve spinal activation of the cAMP response element-mediated gene induction pathway.     

Effect of estradiol and soy phytoestrogens on choline acetyltransferase and nerve growth factor mRNAs in the frontal cortex and hippocampus of female rats.

We report here the effects of oral micronized estradiol and soy phytoestrogens on uterine weight, choline acetyltransferase (ChAT) and nerve growth factor (NGF) mRNAs in the frontal cortex and hippocampus of ovariectomized young and retired breeder rats. Within each age category, 15 bilaterally ovariectomized rats were randomized equally into three groups: control (OVX), estradiol (E2), and soy phytoestrogens (SBE). The OVX rats were fed a casein/lactalbumin-based control diet; the E2 rats were fed with the control diet with added estradiol; and the SBE rats were fed with the control diet with added soy phytoestrogens. After 8 weeks of treatment, blood, uteri, frontal cortex, and hippocampus were collected at necropsy. Results showed that the uterine weights and serum estradiol concentrations were significantly higher in the E2 group compared with those in the OVX and SBE groups. In the hippocampus of young rats, E2 treatment resulted in significantly higher NGF mRNA levels than no treatment (OVX), and NGF mRNA levels in the SBE group were intermediate between the E2 and OVX groups. ChAT mRNA levels were significantly higher in the frontal cortex of E2 and SBE-treated retired breeder rats compared to OVX retired breeder rats. There were no differences among treatment groups for ChAT mRNA levels in the frontal cortex of young rats and in the hippocampus of both young and retired breeder rats. Our data suggest that soy phytoestrogens may function as estrogen agonists in regulating ChAT and NGF mRNAs in the brain of female rats.     

Hypersecretion of follicle-stimulating hormone (FSH) on estrous afternoon in rats treated with RU486 in proestrus

Summary 1. Intact or ovariectomized (OVX) cyclic rats injected or not with RU486 (4 mg/0.2 ml oil) from proestrus onwards were bled at 0800 and 1800h on proestrus, estrus and metestrus. Additional RU486-treated rats were injected with: LHRH antagonist (LHRHa), estradiol benzoate (EB) or bovine follicular fluid (bFF) and sacrified at 1800 h in estrous afternoon. LH and FSH serum levels were determined by RIA.2. RU486-treated intact or OVX rats had decreased preovulatory surges of LH and FSH, abolished secondary secretion of FSH and hypersecretion of FSH in estrous afternoon. The latter was decreased by LHRHa and abolished by EB or bFF. In contrast, EB induced an hypersecretion of LH in RU486-treated rats at 1800h in estrus.3. It can be concluded that in the absence of the proestrous progesterone actions, the absence of the inhibitory effect of the ovary in estrus evoked a LHRH independent secretion of FSH.     

Influence of estradiol on micturition thresholds in the rat: involvement of the hypogastric nerve

Studies have shown that the severity of bladder hyperreflexia induced by acute bladder inflammation varies with the ovarian cycle. These results suggest that the hyperreflexia is modulated by ovarian hormones. Other studies have suggested that such modulation involves the bladder's sympathetic innervation. These hypotheses were tested by assessing the development of bladder hyperreflexia in urethane-anesthetized rats subjected to different hormonal manipulations with or without bilateral hypogastric neurectomy (HYPX). The groups included sham ovariectomy (sham OVX), ovariectomy (OVX), OVX with estradiol replacement (OVX+E), OVX+HYPX, and OVX+HYPX+E. Assessments were performed using repeated cystometrograms (CMGs) to measure micturition thresholds (MT) before and hourly for 3 h after intravesicular treatment with 50% turpentine oil (or olive oil in an OVX+E control group). In the uninflamed bladder, treatment with estradiol increased MTs in the OVX+E group compared with the OVX group. As expected, bladder inflammation induced bladder hyperreflexia in sham OVX rats (studied in estrus). This hyperreflexia was eliminated by OVX and restored by either estradiol replacement or HYPX. Combining estradiol replacement and HYPX (i.e., OVX+E+HYPX) did not increase the severity of bladder hyperreflexia compared with either manipulation alone. These results indicate that the bladder hyperreflexia that is induced by bladder inflammation requires the presence of estradiol and suggest that this hormonal modulation is exerted via the sympathetic control of the bladder, possibly via an increase of beta-adrenergic inhibitory actions on the detrusor muscle. Similar mechanisms may contribute to bladder disorders in postmenopausal women.     

Dietary soy isoflavone-aglycone lowers food intake in female rats with and without ovariectomy

Objective: Estrogens downregulate eating behavior, and soy isoflavones are known to be estrogenic agents. We aimed to examine whether the estrogenic property of soy isoflavones can affect food intake and body weight. Methods and Procedures: Seven‐week‐old male, female, and ovariectomized (OVX) Sprague‐Dawley rats were given free access to a diet containing 100–300 mg total isoflavone/kg diet, or to a control diet, either with or without concurrent administration of estradiol by subcutaneous implantation. Results: Dietary soy isoflavone was shown to lower food intake in female rats, whether or not the animals had undergone ovariectomy. Administration of estradiol lowered the food intake in male rats and in OVX female rats. The decrease in weekly food intake in female rats led to a reduction in their weekly gain in body weight. Dietary soy isoflavone significantly increased the concentration of serum isoflavones, especially equol (a metabolite of daidzein), regardless of gender or ovariectomy. Dietary soy isoflavone did not affect either serum estradiol concentration or uterine and didymus weights, but estradiol administration improved the uterine atrophy in OVX rats, and decreased the didymus weight in male rats. Discussion: Soy isoflavone lowers the food intake in female rats, but not in the male animals. Contrary to the hypothesis currently in vogue, the reduction in food intake caused by soy isoflavone may not be a purely estrogenic effect. This follows from the finding that the effects of soy isoflavones on food intake and on the reproductive organs differ from the corresponding effects produced by estrogen.     

Effect of cyproterone acetate on the reproductive system of the female rat. A histological review.

Effects of cyproterone acetate, a synthetic steroidal compound, on the reproductive organs of female rats have been investigated. This agent caused reduction of ovarian weights indicative of suppression of pituitary gonadotrophins. Oestrogenic nature of cyproterone acetate was investigated in intact and ovariectomized rats taking uterine weight and vaginal keratinization as an index of oestrogenicity. Cyproterone acetate in ovariectomized animals induced vaginal keratinization and increased the uterine weights. These effects were parallel to the effect of oestradiol dipropionate in ovariectomized animals, thus indicating oestrogenic activity of cyproterone acetate. We may conclude that the above compound caused antifertility effects due to its oestrogenic nature at the dose level of 2 mg/alternate day in rats when the compound was administered subcutaneously.