Effects In OVX Rats Research Articles

Cardioprotective effects of vitamin B complex and Ethinyl Estradiol in ovariectomized rats

Background/aim Reduction of female sex hormones is associated with health disorders including cardiovascular diseases such as hypertension. Supplementation with vitamin B complex can lower the incidence of these disorders. The present study aimed to study the potential cardioprotective effects of vitamin B complex and ethinyl estradiol (EE) when administered alone or in combination to hormonal-deprived ovariectomized (OVX) rats. Materials and methods Fifty female Wister rats were classified into five equal groups: the first group included normal rats, the second group was OVX (positive control), and the third to fifth groups were OVX rats that were treated by EE (0.03 mg/kg), vitamin B complex (9.036 mg/kg), and a combination of both treatments, respectively. Treatment continued for eight successive weeks. Blood pressure (BP), cystathionine γ-lyase (CSE), reduced glutathione (R-GSH), superoxide dismutase (SOD), catalase (CAT), and interleukin-β6 (IL-β6) were measured. Results The OVX rats showed a significant increase in BP, reduction in CSE, R-GSH, SOD, and CAT, and increase in IL-β6 levels, whereas the treated OVX rats showed a significant decrease in BP, increase in CSE, R-GSH, SOD, and CAT, and reduction in IL-β6 levels. Conclusion Vitamin B complex and EE exert cardioprotective effects in OVX rats.

Estrogen Receptors α and β Play Major Roles in Ethanol-Evoked Myocardial Oxidative Stress and Dysfunction in Conscious Ovariectomized Rats.

We documented the dependence of ethanol (EtOH)-evoked myocardial dysfunction on estrogen (E2 ), and our recent estrogen receptor (ER) blockade study, in proestrus rats, implicated ERα signaling in this phenomenon. However, a limitation of selective pharmacological loss-of-function approach is the potential contribution of the other 2 ERs to the observed effects because crosstalk exists between the 3 ERs. Here, we adopted a "regain"-of-function approach (using selective ER subtype agonists) to identify the ER subtype(s) required for unraveling the E2 -dependent myocardial oxidative stress/dysfunction caused by EtOH in conscious ovariectomized (OVX) rats. OVX rats received a selective ERα (PPT), ERβ (DPN), or GPER (G1) agonist (10μg/kg; i.v.) or vehicle 30minutes before EtOH (1.0g/kg; infused i.v. over 30minutes) or saline, and the hemodynamic recording continued for additional 60minutes. Thereafter, left ventricular tissue was collected for conducting exvivo molecular/biochemical studies. EtOH had no hemodynamic effects in OVX rats, but reduced the left ventricular contractility index, dP/dtmax , and MAP after acute ERα (PPT) or ERβ (DPN) activation. These responses were associated with increases in the phosphorylation of ERK1/2 and eNOS, and in reactive oxygen species (ROS) and malondialdehyde (MDA) levels in the myocardium. GPER activation (G1) only unraveled a modest EtOH-evoked hypotension and elevation in myocardial ROS. PPT enhanced catalase, DPN reduced ALDH2, while G1 had no effect on the activity of either enzyme, and none of the agonists influenced alcohol dehydrogenase or CYP2E1 activities in the myocardium. Blood EtOH concentration (96.0mg/dl) was significantly reduced following ERα (59.8mg/dl) or ERβ (62.9mg/dl), but not GPER (100.3mg/dl), activation in EtOH-treated OVX rats. ERα and ERβ play major roles in the E2 -dependent myocardial dysfunction caused by EtOH by promoting combined accumulation of cardiotoxic (ROS and MDA) and cardiodepressant (NOS-derived NO) molecules in female myocardium.

The effects of Cordyceps sinensis phytoestrogen on estrogen deficiency-induced osteoporosis in ovariectomized rats.

BackgroundIsoflavones are naturally occurring plant chemicals belonging to the “phytoestrogen” class. The aim of the present study was to examine the effects of isoflavones obtained from Cordyceps sinensis (CSIF) on development of estrogen deficiency-induced osteoporosis in ovariectomized rats.MethodsAfter the rats were treated orally with CSIF, serum alkaline phosphatase (ALP), tartarate resistant acid phosphatase (TRAP), serum osteocalcin (OC), homocysteine (HCY), C-terminal crosslinked telopeptides of collagen type I (CTX), estradiol and interferonγ (IFN-γ) level were examined. At the same time, the urine calcium, plasma calcium, plasma phosphorus and the mass of uterus, thymus and body were also examined.ResultsThe beneficial effects of CSIF on improvement of osteoporosis in rats were attributable mainly to decrease ALP activity, TRAP activity, CTX level and IFN-γ level. At the same time, CSIF also increase the OC and estradiol level in ovariectomized osteopenic rats. The histological examination clearly showed that dietary CSIF can prevent bone loss caused by estrogen deficiency.ConclusionThe significant estrogenic activity of CSIF demonstrated that CSIF has significant estrogenic effects in OVX rats.

The antiosteoporotic activity of central-icaritin (CIT) on bone metabolism of ovariectomized rats.

Central-icaritin (CIT) is a flavonoid aglycone first discovered in our laboratory, which is an isomeric aglycone of icaritin (IT). We wanted to know whether CIT also had anti-osteoporosis activity. In this study, CIT was investigated in an ovariectomized rat (OVX) model. Fifty-six 6-month old female Sprague-Dawley rats were randomly assigned to sham operated group (Sham) and six OVX subgroups (n = 8 each). The OVX rats were then subdivided into six groups treated with vehicle (OVX), icaritin (IT, 40 mg/kg body weight/day), estradiol valerate (EV, 100 μg/kg body weight/day) or CIT (10, 20, and 40 mg/kg body weight/day) for 12 weeks, respectively. Then, the serum biochemical parameters, bone mineral density (BMD), bone biomechanical properties, bone microarchitecture, bone immunohistochemistry and related protein and gene expressions were evaluated. In OVX rats, the increases of body weight, HOP, AKP, and TRACP5b levels, and the decreases of uterus wet weight, femurs weight, BMD, serum OPG/RANKL and OCN were significantly inhibited by CIT treatment. Micro-CT analysis results showed that CIT apparently enhanced trabecular bone compared with the OVX group (p < 0.05). Total femur BMD and biomechanical strength of tibia were significantly improved (p < 0.05) after 12 weeks of CIT administration. In addition, the CIT administration also significantly enhanced the OPG expression, whereas reduced the RANKL expression in femurs according to RT-PCR, western blot assays and immunohistochemical evaluation. CIT had the antiosteoporotic activity, and its antiosteoporotic effects in OVX rats may be stronger than that of IT.

Effects of SCH-23390 in Combination with a Low Dose of 17β-Estradiol on Anxiety-Like Behavior in Ovariectomized Rats

The aim of this study was to explore effects on anxiety-like behavior of D1 dopamine receptor agonist, SKF-38393, and of D1 dopamine receptor antagonist, SCH-23390, given alone or in combination with a low dose of 17β-estradiol (17β-E2) to ovariectomized (OVX) rats. Two weeks after surgery, OVX rats began 14 days of treatment with the vehicle, a low dose of 17β-E2 (5.0 μg/rat, s.c.), SKF-38393 (0.1 mg/kg, i.p.), SCH-23390 (0.1 mg/kg, i.p.), SKF-38393 plus 17β-E2, or SCH-23390 plus 17β-E2. The animals were tested in the black and white model (BWM) and the open field test (OFT). SCH-23390 (0.1 mg/kg, i.p.) alone or in a combination with a low dose of 17β-E2 (5.0 μg/rat, s.c.) resulted in anxiolytic-like effect in OVX rats in the BWM. Repeated treatment with SCH-23390 and 17β-E2 profoundly increased anxiolytic-like effect of single substances exerted per se. Coadministration of SCH-23390 with 17β-E2 increased frequency of rearing and grooming in OVX rats in OFT. SKF-38393 (0.1 mg/kg, i.p.) treatment failed to alter anxiety-like behavior in OVX rats in the BWM. The results of the present study suggest that 17β-E2 and SCH-23390 interact to exert anxiolytic-like action and that each of these drugs can potentiate effects of each other.

Anxiolytic-like effect of quinpirole in combination with a low dose of 17β-estradiol in ovariectomized rats

The aim of this study was to explore effects on anxiety-like behavior of the D2 dopamine receptor agonist, quinpirole and of the D2 dopamine receptor antagonist, sulpiride given alone or in combination with a low dose of 17β-estradiol (17β-E2) to ovariectomized (OVX) rats. Two weeks after surgery, OVX rats began 14 days of treatment with the vehicle, a low dose of 17β-E2 (5.0 μg/rat, s.c.), quinpirole (0.1 mg/kg, i.p.), sulpiride (10.0 mg/kg, i.p.), quinpirole plus 17β-E2 or sulpiride plus 17β-E2. The animals were then tested in the black and white model (BWM) and the open field test (OFT). Quinpirole (0.1 mg/kg, i.p.) administered alone or in a combination with a low dose of 17β-E2 (5.0 μg/rat, s.c.) resulted in anxiolytic-like effect in OVX rats in the BWM. Repeated treatment of quinpirole and 17β-E2 profoundly increased anxiolytic-like effect of the single substances they exert per se. Co-administration of quinpirole with 17β-E2 increased frequency of rearing and grooming in OVX rats in the OFT. Sulpiride (10.0 mg/kg, i.p.) treatment failed to alter anxiety-like behavior in OVX rats in the BWM. In addition, sulpiride blocked the anxiolytic-like effect of 17β-E2 in OVX rats. Application of neither sulpiride nor sulpiride plus 17β-E2 led to any changes of rearing and grooming behavior in OVX rats in the OFT. The results of the present study suggest that 17β-E2 and quinpirole interact to exert anxiolytic-like action and that each of these drugs can potentiate effects of each other. Further research is needed to elucidate detailed mechanisms by which quinpirole and 17β-E2 exert synergistic effect on anxiety-related behavior.

Hypocholesterolemic effect of capsaicinoids by increased bile acids excretion in ovariectomized rats

This study investigated the interaction of dietary capsaicinoids with the mRNA and protein expressions of key receptors and enzymes involved in cholesterol metabolism in ovariectomized (OVX) rats. Female Sprague-Dawley rats were subjected to sham operation or ovariectomy. The sham group and OVX control group were fed with high-cholesterol diets, whereas the treatment group (control diet containing 0.01% capsaicinoids) was fed with high-cholesterol plus 0.01% capsaicinoids diet for 21 days. Capsaicinoids significantly decreased the body weight gain, plasma total cholesterol, LDL cholesterol, and triacylglycerol without affecting the high-density lipoprotein cholesterol in the OVX rats. The change in plasma lipoprotein profile was accompanied by a greater excretion of total bile acid in feces and small intestinal contents. Western blot and real-time PCR analyses revealed that capsaicinoids significantly enhanced the expressions of hepatic cholesterol 7α-hydroxylase and transient receptor potential vanilloid type-1 but did not affect the expression of 3-hydroxy-3-methylglutaryl-CoA reductase in the OVX rats. Capsaicinoids have cholesterol-lowering effects in OVX rats. The hypocholesterolemic activity of capsaicinoids is caused by the stimulating conversion of cholesterol to bile acids by upregulation of cholesterol 7α-hydroxylase expression and the increase in fecal total bile acid excretion.

Effect of a derived herbal recipe from an ancient Chinese formula, Danggui Buxue Tang, on ovariectomized rats

Ethnopharmacological relevance: Radix Astragali (root of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao, RA), Radix Angelicae sinensis (root of Angelica sinensis (Oliv.) Diels, RAS) and Folium Epimedii (leaves of Epimedium brevicomum Maxim., FE) are three of the extensively applied herbal remedies among traditional Chinese medicines for gynecological disorders and osteoporosis. A derivative herbal recipe—RRF, composed of the three medicines with a weight ratio of 5:1:5, is derived from a famous Chinese herbal formula—Danggui Buxue Tang (DBT). RRF has shown noteworthy protective effect in ovariectomized rats, which might represent a promising candidate for the treatment of perimenopausal disorders. The aim of this study was to investigate the herbal recipe RRF for its efficacy on perimenopausal disorders and the underlying mechanisms via ovariectomy (OVX) models. Materials and methodsAn experimental model of OVX female rats was applied. Vehicle (Sham and OVX group), RRF (564, 282 and 141mg/kg/d) and conjugated equine estrogens (CEE, 0.1mg/kg/d, reference drug) were all administrated orally once daily for 16 weeks post operation. After the treatment, radioimmunoassay for estradiol (E2), lutenizing hormone (LH), follicle stimulating hormone (FSH) and β-endorphin (β--EP), neurotransmitter determination by high-performance liquid chromatography with electrochemical detector (HPLC-ECD) for norepinephrine (NE), dopamine (DA), 5-hydroxytryptamine (5-HT) and 5-HIAA (5-hydroxyindoleacetic acid), bone mineral density (BMD) assay as well as lipid peroxidation assessment, were carried out to probe into the effectiveness of RRF. Results(1) RRF treatment enhanced E2 synthese while diminished the elevated serum FSH and LH levels; in terms of neurotransmitter, β-EP syntheses rallied whereas the hypothalamic NE, DA and 5-HT release experienced varying mitigation in OVX female rats. (2) Repeated administration of RRF was able to attenuate osteoporosis by elevating the BMD levels of total body, and arrest the bone trabeculae degradation. (3) RRF exposure decreased serum levels of constituent MDA and increased endogenous SOD activity. ConclusionsResults of the current studies revealed that RRF was capable of acting at multiple targets which presumably underlay its potential protective effect in OVX rats mimicking symptoms as observed in perimenopausal women. Hence, RRF might represent a promising candidate in the treatment of perimenopausal disorders in midlife women.

Exacerbation of myocardial dysfunction and autonomic imbalance contributes to the estrogen-dependent chronic hypotensive effect of ethanol in female rats

Our previous studies showed that the hypotensive effect of chronic ethanol in female rats is reduced by ovariectomy (OVX) rats and was restored after estrogen replacement (OVXE2). Further, in randomly cycling rats, chronic ethanol increased cardiac parasympathetic dominance and subsequently reduced myocardial contractility and blood pressure (BP). In this study, we tested the hypothesis that alterations in myocardial contractility and sympathovagal control account for the E2 exacerbation of the hemodynamic effects of ethanol. BP, myocardial contractility (+dP/dtmax), and spectral cardiovascular autonomic profiles were evaluated in radiotelemetered OVX, and OVXE2 rats receiving liquid diet with or without ethanol (5%, w/v) for 13weeks. In OVX rats, ethanol caused modest hypotension along with significant increases in +dP/dtmax during weeks 2–5. The high-frequency (IBIHF, 0.75–3Hz) and low-frequency (IBILF, 0.25–0.75Hz) bands of interbeat intervals were briefly increased and decreased, respectively, by ethanol. Compared with its effects in OVX rats, chronic treatment of OVXE2 rats with ethanol elicited significantly greater and more sustained reductions in systolic (SBP) and diastolic (DBP) blood pressures and +dP/dtmax. Altered sympathovagal balance and parasympathetic overactivity were more evident in ethanol-treated OVXE2 rats as suggested by the sustained: (i) increases in high-frequency bands of interbeat intervals (IBIHF, 0.75–3Hz), and (ii) decreases in low-frequency IBI bands (IBILF, 0.25–0.75Hz), IBILF/HF ratio and +dP/dtmax. The plasma ethanol concentration was not affected by changes in the hormonal milieu. These findings suggest that estrogen exacerbates the ethanol-evoked reductions in myocardial contractility and BP and the associated parasympathetic overactivity in female rats.

Chronic treatment with the nitric oxide synthase inhibitor, L-NAME, attenuates estradiol-mediated improvement of learning and memory in ovariectomized rats

INTRODUCTION:The role of ovarian hormones and nitric oxide in learning and memory has been widely investigated.OBJECTIVE:The present study was carried out to evaluate the effect of the nitric oxide synthase (NOS) inhibitor, N (G)-nitro-L-arginine methyl ester (L-NAME), on the ability of estradiol to improve learning in OVX rats using the Morris water maze.METHODS:Forty rats were divided into five groups: (1) ovariectomized (OVX), (2) ovariectomized-estradiol (OVX-Est), (3) ovariectomized-L-NAME 10 (OVX-LN 10), (4) ovariectomized-L-NAME 50 (OVX-LN 50) and (5) ovariectomized-estradiol-L-NAME 50 (OVX-Est-LN 50). The animals in the OVX-Est group were treated with a weekly injection of estradiol valerate (2 mg/kg; i.m.). The OVX-LN 10 and OVX-LN 50 groups were treated with daily injections of 10 and 50 mg/kg L-NAME (i.p.), respectively. The animals in the OVX-Est-LN 50 group received a weekly injection of estradiol valerate and a daily injection of 50 mg/kg L-NAME. After 8 weeks, all animals were tested in the Morris water maze.RESULTS:The animals in the OVX-Est group had a significantly lower latency in the maze than the OVX group (p<0.001). There was no significant difference in latency between the OVX-LN 10 and OVX-LN 50 groups in comparison with the OVX group. The latency in the OVX-Est-LN 50 group was significantly higher than that in the OVX-Est group (p<0.001).CONCLUSION:These results show that L-NAME treatment attenuated estradiol-mediated enhancement of spatial learning and memory in OVX rats, but it had no significant effect in OVX rats without estrogen, suggesting an interaction of nitric oxide and estradiol in these specific brain functions.

Neurohormonal mechanisms of the antidepressant effect of ketanserin in ovariectomized rats

In the present study we investigated the effects of chronic administration of m-CPP (0.5 mg/kg, i.p.), a 5-HT2B/2C receptor agonist, and ketanserin (0.1 mg/kg, i.p.), a 5-HT2A/2C receptor antagonist, alone or in a combination with 17β-estradiol (0.5 μg per animal, i.m.) over 14 days on depressive behavior and the concentration of different monoamines in the hippocampus in adult ovariectomized (OVX) female rats. Depression-like behavior was assessed using the Porsolt’s test. The concentrations of monoamines and their metabolites were determined using HPLC. We found that chronic ketanserin administration has an antide-pressant effect in OVX rats. Chronic ketanserin administration in combination with 17β-estradiol in OVX females potentiated antidepressant action. The antidepressant effect of ketanserin in OVX rats correlated with the restoration of noradrenergic, serotonergic, and dopaminergic neurotransmission in the hippocampus. Our data indicate a close interaction between the ovary hormonal and serotonergic systems of the brain in mechanisms of depression.

Hepatic VLDL-TG Production and MTP Gene Expression are Decreased in Ovariectomized Rats: Effects of Exercise Training

The present study was designed to investigate the effects of estrogen withdrawal and exercise training on hepatic very low density lipoprotein-triglyceride (VLDL-TG) production and on expression of genes involved in hepatic VLDL synthesis in response to lipid infusion. Female Sprague-Dawley rats underwent ovariectomy (Ovx), sham surgery (Sham), and Ovx with 17β-estradiol supplementation (OvxE2) before being subdivided into sedentary (Sed) and trained (Tr) groups for 8 weeks. Exercise training consisted of continuous running on a rodent treadmill 5 times/wk. At the end of the 8-week period, all rats in the fasted state were intravenously infused with a 20% solution of Intralipid for 3-h followed by an injection of Triton WR-1339 to block lipoprotein lipase activity. Plasma TG accumulation was subsequently measured during 90 min to estimate VLDL-TG production. An additional control group consisting of Sham-Sed rats was infused with saline (0.9% NaCl). Estrogen withdrawal resulted in higher (p<0.01) liver fat accumulation concomitantly with lower (p<0.01) VLDL-TG production and lower mRNA and protein content of hepatic microsomal triglyceride transfer protein (MTP). All of these effects in Ovx rats were corrected with estrogen supplementation. Training in Ovx rats reduced (p<0.01) liver fat accumulation and further reduced (p<0.01) hepatic VLDL-TG production along with gene expression of MTP and diacylglycerol acyltransferase-2 (DGAT-2). It is concluded that VLDL-TG synthesis and/or secretion is decreased in Ovx rats probably via MTP regulation and that this decrease may constitute one of the factors involved in hepatic fat accumulation. The training effect on reducing VLDL production was independent of the estrogenic status.

Kisspeptin Regulates Prolactin Release through Hypothalamic Dopaminergic Neurons

Prolactin (PRL) is tonically inhibited by dopamine (DA) released from neurons in the arcuate and periventricular nuclei. Kisspeptin plays a pivotal role in LH regulation. In rodents, kisspeptin neurons are found mostly in the anteroventral periventricular and arcuate nuclei, but the physiology of arcuate kisspeptin neurons is not completely understood. We investigated the role of kisspeptin in the control of hypothalamic DA and pituitary PRL secretion in adult rats. Intracerebroventricular kisspeptin-10 (Kp-10) elicited PRL release in a dose-dependent manner in estradiol (E2)-treated ovariectomized rats (OVX+E2), whereas no effect was found in oil-treated ovariectomized rats (OVX). Kp-10 increased PRL release in males and proestrous but not diestrous females. Associated with the increase in PRL release, intracerebroventricular Kp-10 reduced Fos-related antigen expression in tyrosine hydroxylase-immunoreactive (ir) neurons of arcuate and periventricular nuclei in OVX+E2 rats, with no effect in OVX rats. Kp-10 also decreased 3,4-dihydroxyphenylacetic acid concentration and 3,4-dihydroxyphenylacetic acid-DA ratio in the median eminence but not striatum in OVX+E2 rats. Double-label immunofluorescence combined with confocal microscopy revealed kisspeptin-ir fibers in close apposition to and in contact with tyrosine hydroxylase-ir perikarya in the arcuate. In addition, Kp-10 was not found to alter PRL release from anterior pituitary cell cultures regardless of E2 treatment. We provide herein evidence that kisspeptin regulates PRL release through inhibition of hypothalamic dopaminergic neurons, and that this mechanism is E2 dependent in females. These findings suggest a new role for central kisspeptin with possible implications for reproductive physiology.

The management of menopause with complementary and alternative medicine using an experimental model: Ovariectomized rats

The purpose of this research was to assess the effects of the flower essences She Oak and Bush Fuchsia on behavioral anxiety in ovariectomized (OVX) rats. For four weeks, OVX rats received the flower essences She Oak, Bush Fuchsia or a combination of the two. After flower therapy, the animals were subjected to an elevated plus maze (EPM) behavioral anxiety-test. Cortisol blood level was also evaluated. OVX rats treated with the flower essence She Oak became less anxious and had more entries in the EPM open arms. On the other hand, OVX rats treated with the Bush Fuchsia essence spent more time in the EPM closed arms. This finding is similar to those obtained with controls. In addition, OVX rats that received She Oak and Bush Fuchsia in combination presented the same results as those receiving the Bush Fuchsia alone. Our results suggest that the flower essence She Oak could have an anxiolytic effect in OVX rats, but that the combination therapy of the She Oak and Bush Fuchsia could avoid the effects of the She Oak.

Effects of acute and 2-Day genistein treatment on cardiac function and ischemic tolerance in ovariectomized rats

Genistein, a naturally occurring isoflavonic phytoestrogen associated with reduced incidence of heart disease, may be a possible alternative treatment for postmenopausal women with heart disease. This study examined the effects of genistein on in vitro heart function and ischemic tolerance in ovariectomized (OVX) Sprague-Dawley rats. To examine the acute effects of genistein on cardiac function, isolated working hearts were perfused under aerobic conditions with increasing concentrations of genistein (10-150 microM). A separate group of OVX rats was used to assess ischemic tolerance: treated rats received genistein (250 mg/kg, dissolved in 200 microL dimethyl sulfoxide [DMSO]) injected once daily for 2 days, and control rats received DMSO only. After treatment, hearts were perfused for 30 minutes under aerobic conditions and then subjected to 20 minutes of global no-flow ischemia by clamping the preload and afterload lines, followed by 30 minutes of reperfusion. Genistein was associated with improvements in mechanical function in OVX rat hearts (n = 5) with maximum increases in contractility (259 mm Hg/sec above baseline) and cardiac output (7 mL/min above baseline) observed with 30 microM of genistein (both, P < 0.05). Relative to baseline, genistein-treated hearts (n = 5) also had greater ischemic tolerance than did control hearts (n = 6) and significant improvements in mean (SEM) recovery of contractility (to 75.0% [9.7%] of preischemic function; P < 0.05) and cardiac output (to 48.8% [12.3%] of preischemic function; P < 0.05) after reperfusion. These effects occurred without significant changes in myocardial levels of nonprotein thiols or thiobarbituric acid reactive substances, although a reduction in mean glucose transporter protein 4 content (13.2% [2.7%]; P < 0.05) was observed in genistein-treated hearts. No significant changes in blood pressure were observed with genistein. Despite the lack of significant changes in physical characteristics, 2-day treatment with genistein was associated with significant cardioprotective effects in OVX rats, suggesting a potential therapeutic role in postmenopausal women.

Evidences for antiosteoporotic and selective estrogen receptor modulator activity of silymarin compared with ethinylestradiol in ovariectomized rats

Recently, growing multiple uses of silymarin (SIL) as a complementary and alternative medicine, for alcohol-induced liver disease, acute and chronic viral hepatitis, as well as some other nonhepatic indications have been reported. Therefore, more attention should be paid for the hormonal side effects of SIL. Since the available data on the possible estrogenic effects of SIL is rather rare, this study aimed to further elucidate the different estrogenic effects and antiosteoporotic activity of SIL in ovariectomized (OVX) rats. OVX rats were treated chronically (12 weeks) with ethinylestradiol (EE) or SIL. Uterine and body weight were measured in all animals. Biochemical markers of bone formation (total alkaline phosphatase (ALP), calcium, phosphorus and osteocalcin), endocrinological analysis (estradiol (E2), luteinizing hormone (LH), follicle stimulating hormone (FSH) and parathyroid hormone (PTH)) and serum total cholesterol and total lipids were estimated. Formalin fixed femora and uteri specimens were used for histopathological examination. In addition, the binding property of SIL to the two estrogen receptors (ER) subtypes was tested by molecular docking. EE (strong) and SIL (mild) stimulated uterine weight (increased uterus hyperplastic endometrial glands) but EE only prevented body weight gain following OVX. Treatment of OVX rats with both EE and SIL resulted in protection of trabecula thickness, decreased serum levels of ALP and increased serum levels of both calcium and phosphorus. In contrast to EE, SIL did not decrease OVX induced serum osteocalcin. EE not SIL decreased serum cholesterol, total lipids, LH and FSH and increased serum E2. Both EE and SIL increased serum PTH. The docking study revealed a high affinity of SIL towards ERbeta. In conclusion, findings derived in the present study presented an overview of SIL many estrogenic effects in OVX rats. SIL significantly prevents the bone loss in rats induced by OVX with mild proliferative effects in uterus. The observed effects may be due to additive beneficial effect of SIL on bone either due to direct interaction with ERbeta or increasing bone formation parameters including calcium, phosphorus, osteocalcin and PTH.

Effects of dietary equol administration on ovariectomy induced bone loss in Sprague–Dawley rats

Oestrogen deficiency leads to a considerable bone loss, thus, osteopenia and osteoporosis are serious complications after menopause. ObjectivesTo evaluate the effects of a daidzein metabolite equol on bone mass density (BMD) and markers of bone remodelling in an ovariectomized (ovx) rat model of postmenopausal bone loss and compare them with the effects of 17β-estradiol. MethodsTwenty-eight female Sprague–Dawley rats were ovx and fed soy-free chow only (control group, n=8), or with the addition of oestradiol-3 benzoate (E2B) (10mg/kg, n=10) or equol (400mg/kg, n=10). At baseline and after 6-week treatment period, proximal tibia and lumbar spine BMD were measured using computer tomography. Animals were then sacrificed, blood was collected and uteri were removed. ResultsSimilarly to E2B, dietary equol decreased weight gain and showed mild uterotropic activity. E2B attenuated ovx induced BMD loss at proximal tibia whereas equol had no effect. At lumbar spine, however, equol not only attenuated trabecular bone loss but also increased its density. This effect was also apparent in animals treated with E2B. Cortical BMD at proximal tibia and lumbar spine were not very much influenced by ovx and treatment with E2B or equol did not induce significant changes at these sites. Plasma osteocalcin and type I collagen fragments (cross-laps) in equol treated animals did not differ from the controls whereas in E2B treated animals they were both significantly decreased. ConclusionsIn spite of its mild uterotropic potential, dietary equol shows limited bone sparing effects in ovx rats.

Plant extracts for the treatment of menopausal women: Safe?

Objectives The recently published data concerning putatively dangerous effects of classical hormone therapy resulted in increased sales of plant derived substances, which claim beneficial effects on climacteric and postmenopausal complaints and diseases. Soy and red clover extracts containing isoflavones have estrogenic effects in cell biological and animal experimental models but commercial advertisements often claim beneficial effects in mammary glands by preventing occurrence of malignancies. Black cohosh preparations are also increasingly used, and they appear to be devoid of estrogenic effects in the uterus. Their effects in the mammary gland have not yet been thoroughly studied. Methods Therefore, we studied the effects of genistein, the main isoflavone in soy or red clover preparations and of the black cohosh extract Cimicifuga racemosa (CR) or Actea racemosa BNO 1055 in the uterus and mammary gland of ovariectomized (ovx) rats and compared them with the effects of estradiol. Serum LH levels were also measured as an indicator of a hypothalamic/pituitary effects of the test substances. Results Genistein and E2, both stimulated uterine weight and several estrogen regulated genes. Lobulo-alveolar growth of 20 mammary glands as well as the expression of the nuclear protein proliferating cell nuclear antigen (PCNA, a proliferation marker) was also stimulated by E2 and genistein. The CR extract BNO 1055 was devoid of such estrogenic effects in the uterus and mammary gland. E2 and to lesser degree CR inhibited serum LH levels whereas genistein had no effects on this hormone. Conclusions E2 and genistein share uterotropic and mammatropic effects in ovx rats. If occurring in postmenopausal women this may endanger these organs to develop malignancies. Serum LH levels were inhibited by E2 and the CR BNO 1055 extract whereas genistein had no estrogenic effect in the hypothalamus and it is therefore unlikely that genistein inhibits climacteric complaints.

Oxytocin decreases corticosterone and nociception and increases motor activity in OVX rats

Objectives: In the present study the effects of oxytocin administered subcutaneously (s.c.) or intravaginally (i.vag.) on spontaneous motor activity, nociceptive thresholds and plasma corticosterone levels were examined in female ovariectomized (OVX) rats. Methods: Oxytocin (1 mg/kg s.c. or 100 μg i.vag.) was administered once a day for 10 days to OVX rats. Controls received saline s.c. or cellulose gel i.vag. Spontaneous motor activity was observed in an open-field arena, nociceptive thresholds were investigated by the tail-flick test, and corticosterone and oxytocin plasma levels were measured by radioimmunassay, 3, 4 and 5 days respectively, after the end of the treatment period. Results: Both oxytocin administered s.c. and i.vag. increased forward locomotion ( p < 0.05) and nociceptive thresholds ( p < 0.05) significantly. In addition, oxytocin s.c. increased the amount of locomotor activity ( p < 0.05). Plasma corticosterone levels were decreased ( p < 0.05) and oxytocin levels were unchanged when measured 5 days after the last administration of oxytocin s.c. or i.vag. Conclusion: The present data indicate that oxytocin induces a spectrum of long-lasting effects in OVX rats, including an increase in spontaneous motor activity, elevation of nociceptive thresholds and decrease of corticosterone levels. Similar effects may be induced by estrogens. In addition, these data indicate that i.vag. administration of oxytocin may be used to induce oxytocin-mediated effects.

Specific bone-protective effects of metabolites/derivatives of tamoxifen and clomiphene in ovariectomized rats

In the ovariectomized (ovx) rat, the nonsteroidal antiestrogens, clomiphene (CLO) and tamoxifen (TAM), at dose levels that prevent development of osteopenia to a degree approaching that of 17β-estradiol are, in contrast to 17β-estradiol, only weakly uterotrophic. Metabolites of CLO and TAM might contribute differentially to these effects. Thus, we have evaluated bone protective and uterine effects in ovx rats of two such metabolites: 4-hydroxy CLO, produced by p-hydroxylation of CLO; and 4HTA, produced from TAM by stepwise replacement of its dimethylaminoethyl side chain with an acetic acid moiety, accompanied by p-hydroxylation. Also reported are effects of D4HTA, the dihydrodesethyl derivative of 4HTA previously characterized as a full estrogen mimetic in vitro. Administration of 4-hydroxy CLO (2.5 mg/kg subcutaneously) 5 days/week for 5 weeks to 3-month-old ovx rats resulted in complete prevention of bone loss and suppression of bone turnover to levels comparable to those of intact controls and to those of ovx animals similarly receiving 17β-estradiol (10 μg/kg). However, uterine weight in animals receiving 4-hydroxy CLO was 64% less than that in 17β-estradiol-treated animals. Although 4HTA (3.7 mg/kg s.c.) had a modest uterotrophic effect, it did not prevent bone loss associated with ovariectomy. In contrast, D4HTA (3.6 mg/kg s.c.) partially reduced bone turnover indicators and cancellous bone loss in a manner similar in many ways to that observed in TAM-treated ovx animals, but it had no uterotrophic effect. These results suggest that, although 4HTA does not contribute to the bone-protective effect of TAM, 4-hydroxy CLO might augment that of CLO.