Animal Model Of Menopause Research Articles

The role of vitamin D in menopausal women's health.

Vitamin D (VD) is known to play an important role in the maintenance of calcium homeostasis and bone metabolism. In recent years, there has also been a growing interest in Vitamin D for health issues beyond the bones. Menopausal women are at risk of reduced bone density and increased risk of fracture due to a decline in estrogen levels. There is also an increased risk of cardiovascular disease, diabetes and hyperlipidaemia due to impaired lipid metabolism. The menopausal and emotional symptoms due to menopause are also increasingly prominent. This article summarizes the role of Vitamin D in menopausal women's health, including the effects of Vitamin D on skeletal muscle, cardiovascular disease, Genitourinary Syndrome of Menopause (GSM), cancer and emotional symptoms. Vitamin D regulates the growth of vaginal epithelial cells and alleviates genitourinary tract problems in menopausal women. Vitamin D also modulates immune function and influences the production of adipokines. Vitamin D and its metabolites also have an anti-proliferative effect on tumour cells. This narrative review, by summarizing recent work on the role of Vitamin D in menopausal women and in animal models of menopause, aims to provide a basis for further development of the role of Vitamin D in the health of menopausal women.

Probiotic treatment with Kefir reduces vascular oxidative stress while suppressing COX2 mediated relaxation in intestinal arteries of an animal model of menopause

Functional foods such as probiotics are known to have benefits in various diseases including metabolic disorders and cardiovascular disease (CVD). In women, CVD has been shown to be linked with their gut microbiota and hormones. Here, we have evaluated the effects of chronic Kefir, a fermented milk beverage in Russia, Central Asia, Middle East and Eastern Europe, on mesenteric artery, using an animal model of menopause focusing on the superoxide anion and COX2 pathways. Two-month-old female Wistar rats were ovariectomized and treated by gavage with Kefir (5 % w/v, 3 mL/kg/day) or milk (Control) during two months. After this period, third-order mesenteric artery segments were isolated and mounted in a myograph system for evaluation of concentration-response curves to acetylcholine. We performed western blot analyses and measured oxidative stress through dihydroethidium (DHE) staining. Kefir reduced vascular oxidative stress, despite not changing SOD2 levels. COX2 levels were not changed by kefir, despite an apparent tendency towards reduction. However, in the functional experiments, under incubation with a COX2 inhibitor, a suppression of this pathway was observed in the kefir group, which suggests an interaction between inflammatory pathways and oxidative stress in this model. The effect of acute incubation with a superoxide anion scavenger on vascular responsiveness was equal in both groups. Kefir reduces vascular oxidative stress levels while suppressing COX2-mediated relaxation in mesenteric vessels in an animal model of menopause; which appears to involve an interplay between these two factors.

Ekstrak Etanol Ubi Jalar Ungu untuk Mencegah Peningkatan pH Vagina setelah Ovariektomi Bilateral pada Tikus Wistar

AVaginal atrophy is one of the most common health problems in postmenopausal women. The disease is characterized by decreasing layers and maturation index of the vaginal epithelium and an increase in vaginal pH. A decrease in vaginal acidity will increase the susceptibility to infections since acidic pH protects the vagina from pathogens infection. The previous study has proven that phytoestrogens were effective to improve the microstructures of the vaginal, reduce urogenital complaints, and improve vaginal pH. The purple sweet potato (Ipomea batatas L.) which is cultivated in Bali was recognized for its high anthocyanin content and was reported to have phytoestrogen activity. The aim of the present study is to evaluate the effect of purple sweet potato on vaginal pH in an animal model of menopause. The randomized pre-test post-test control group design study was conducted using 36 bilateral ovariectomized female Wistar rats as an animal model of menopause. The animals were divided randomly into a control group (T0) which was given saline and a treatment group (T1) given an ethanolic extract of purple sweet potato 400 mg/day for 30 days. Vaginal pH was measured before treatment, every week during treatment, and after treatment. The result of the study showed that there was an increase in vaginal pH of the T0 on the 2nd and 3rd week, and after treatment (P

Effect of Yakae-Prajamduen-Jamod Traditional Thai Remedy on Cognitive Impairment in an Ovariectomized Mouse Model and Its Mechanism of Action.

Cognitive impairment is a neurological symptom caused by reduced estrogen levels in menopausal women. The Thai traditional medicine, Yakae-Prajamduen-Jamod (YPJ), is a formula consisting of 23 medicinal herbs and has long been used to treat menopausal symptoms in Thailand. In the present study, we investigated the effects of YPJ on cognitive deficits and its underlying mechanisms of action in ovariectomized (OVX) mice, an animal model of menopause. OVX mice showed cognitive deficits in the Y-maze, the novel object recognition test, and the Morris water maze. The serum corticosterone (CORT) level was significantly increased in OVX mice. Superoxide dismutase and catalase activities were reduced, while the mRNA expression of IL-1β, IL-6, and TNF-α inflammatory cytokines were up-regulated in the frontal cortex and hippocampus of OVX mice. These alterations were attenuated by daily treatment with either YPJ or 17β-estradiol. HPLC analysis revealed that YPJ contained antioxidant and phytoestrogen constituents including gallic acid, myricetin, quercetin, luteolin, genistein, and coumestrol. These results suggest that YPJ exerts its ameliorative effects on OVX-induced cognitive deficits in part by mitigating HPA axis overactivation, neuroinflammation, and oxidative brain damage. Therefore, YPJ may be a novel alternative therapeutic medicine suitable for the treatment of cognitive deficits during the menopausal transition.

RANKL elevation activates the NIK/NF-κB pathway, inducing obesity in ovariectomized mice.

Menopausal women are susceptible to visceral obesity, which increases the risk of metabolic disorders. However, the mechanisms of menopause-induced visceral fat accumulation are not fully understood. Circulating levels of receptor activator of nuclear factor-kappa B (NF-κB) ligand (RANKL) are elevated in an animal model of menopause. RANKL, a multifunctional cytokine, activates the NF-κB pathway, which serves as a pivotal mediator of inflammatory responses. Here, we investigated whether RANKL-induced non-canonical NF-κB pathway activation induces inflammation and lipid accumulation in adipose tissues. RANKL induced Tnfa expression via the non-canonical NF-κB pathway in bone marrow cells. We therefore analyzed aly/aly mice, in which the non-canonical NF-κB pathway is not activated, owing to an inactive form of NF-κB-inducing kinase. A postmenopausal obesity model was generated by ovariectomy and subsequent high-fat and high-sucrose diet feeding. In aly/aly mice with postmenopausal obesity, serum RANKL levels were elevated, and hepatic lipid accumulation and adipocyte hypertrophy were suppressed, resulting in reduced macrophage infiltration and inflammatory cytokine mRNA expression in visceral adipose tissue. Furthermore, aly/aly mice showed protection from glucose intolerance and insulin resistance, which were observed in ovariectomized WT obese mice. These findings indicate that non-canonical NF-κB pathway activation via serum RANKL elevation contributes to postmenopausal obesity.

Protective effects of Lyciumbarbarum polysaccharide onovariectomy‑induced cognition reduction in aging mice.

Women experience cognitive decline as they age due to the decrease in estrogen levels following menopause. Currently, effective pharmaceutical treatments for age-related cognitive decline are lacking; however, several Traditional Chinese medicines have shown promising effects. Lycium barbarum polysaccharides (LBPs) were found to exert a wide variety of biological activities, including anti-inflammatory, antioxidant and anti-aging effects. However, to the best of our knowledge, the neuroprotective actions of LBP on cognitive impairment induced by decreased levels of estrogen have not yet been determined. To evaluate the effects of LBP on learning and memory impairment in an animal model of menopause, 45 female ICR mice were randomly divided into the following three groups: i) Sham; ii) ovariectomy (OVX); and iii) OVX + LBP treatment. The results of open-field and novel object recognition tests revealed that mice in the OVX group had learning and memory impairments, and lacked the ability to recognize and remember new objects. Notably, these deficits were attenuated following LBP treatment. Immunohistochemical staining confirmed the protective effects of LBP on hippocampal neurons following OVX. To further investigate the underlying mechanism of OVX in mice, mRNA sequencing of the hippocampal tissue was performed, which revealed that the Toll-like receptor 4 (TLR4) inflammatory signaling pathway was significantly upregulated in the OVX group. Moreover, reverse transcription-quantitative PCR and immunohistochemical staining demonstrated that OVX induced hippocampal injury, upregulated the expression levels of TLR4, myeloid differentiation factor 88 and NF-κB, and increased the expression of TNF-α, IL-6 and IL-1β inflammatory factors. Conversely, LBP treatment downregulated the expression levels of mRNAs and proteins associated with the TLR4/NF-κB signaling pathway, decreased the inflammatory response and reduced neuronal injury in mice that underwent OVX. In conclusion, the findings of the present study indicated that oral LBP treatment may alleviate OVX-induced cognitive impairments by downregulating the expression levels of mRNAs and proteins associated with the TLR4/NF-κB signaling pathway, thereby reducing neuroinflammation and damage to the hippocampal neurons. Thus, LBP may represent a potential agent for the prevention of learning and memory impairments in patients with accelerated aging caused by estrogen deficiency.

Ovariectomy reduces the cardiac cytoprotection in rats exposed to particulate air pollutant.

Fine particulate matter (PM2.5) has been considered a risk factor for cardiovascular diseases by inducing an oxidative and inflammatory phenotype. Besides, the reduction of 17β-estradiol (E2) levels during menopause is a natural risk for cardiovascular outcomes. During the E2 downfall, there is a high requirement of the 70-kDa heat shock proteins (HSP70), which present essential antioxidant, anti-inflammatory, and anti-senescence roles. We investigated if the ovariectomy, an animal model for menopause, could induce additional effects in cardiac health by impairing oxidative and heat shock response parameters of female rats chronically exposed to residual oil fly ash (ROFA; an inorganic fraction of PM2.5). Thus, ROFA was obtained from São Paulo (Brazil) and solubilized it in saline. Further, female Wistar rats were exposed to 50μL of saline (control group) or ROFA solution (250μg) (polluted) by intranasal instillation, 5days/week, 12weeks. At the 12th week, animals were subdivided into four groups (n = 6 p/group): control, OVX, polluted, and polluted + OVX. Control and polluted were submitted to false surgery, while OVX and polluted + OVX were ovariectomized. ROFA or saline exposure continued for 12weeks. Ovariectomy reduced the cardiac catalase activity and iHSP70 expression in female rats exposed to ROFA. Neither plasma eHSP72 levels nor H-index (eHSP72 to cardiac iHSP70 ratio) was affected. In conclusion, ovariectomy reduces the cardiac cytoprotection and antioxidant defense, and enhances the susceptibility to premature cellular senescence in rats exposed to ROFA.

Aqueous extract of pomegranate enriched in ellagitannins prevents anxiety-like behavior and metabolic changes induced by cafeteria diet in an animal model of menopause

Women around menopause are vulnerable to present psychiatric and metabolic disorders; thus, therapies that contribute to treat both pathologies are required. Previous reports showed that an aqueous extract of pomegranate (Punica granatum), enriched in ellagitannins, exerts an antidepressant-like effect in ovariectomized rats.We analyze whether this aqueous extract of P. granatum (AE-PG) prevents the anxiety-like behavior induced by a cafeteria diet (CAF) in middle-aged ovariectomized rats at the same time that it prevents an increase in body weight, glucose, lipids, and the changes on mRNA expression of the peroxisome proliferator-activated receptor-gamma (PPAR-γ) in the liver. Also, the effects of AE-PG on the protein levels of PPAR-γphospho-PPAR-γ, extracellular signal-regulated protein kinase (ERK1/2) and phospho-ERK1/2 were measured in the hippocampus and amygdala.CAF induced anxiety-like behavior, augmented lipids and glucose blood levels, body weight, visceral fat, insulin resistance, and decreased mRNA expression of PPAR-γ in the liver. In rats fed with the CAF, AE-PG prevented the anxiety-like behavior, reduced body weight, lowered lipid levels, reduced insulin resistance, and increased PPAR-γ mRNA expression in the liver. In the hippocampus, ERK1/2 but not PPAR-γ protein levels were decreased by CAF, while AE-PG prevented these effects. In the amygdala, CAF increased the phosphorylation of PPARγ, and AE-PG prevented it. In contrast, AE-PG rescued the decreased ERK1/2 protein level in the hippocampus caused by CAF.In conclusion, AE-PG treatment prevented anxiogenic and metabolic effects induced by CAF, and its effects appear to be mediated by ERK1/2 and PPARγ depending on the brain area studied.

Encapsulated Mulberry Fruit Extract Alleviates Changes in an Animal Model of Menopause with Metabolic Syndrome.

Currently, the therapeutic strategy against metabolic syndrome and its complications is required due to the increasing prevalence and its impact. Due to the benefits of both mulberry fruit extract and encapsulation technology, we hypothesized that encapsulated mulberry fruit extract (MME) could improve metabolic parameters and its complication risk in postmenopausal metabolic syndrome. To test this hypothesis, female Wistar rats were induced experimental menopause with metabolic syndrome by bilateral ovariectomy (OVX) and high-carbohydrate high-fat (HCHF) diet. Then, they were orally given MME at doses of 10, 50, and 250 mg/kg BW for 8 weeks and the parameters, such as percentage of body weight gain, total cholesterol, triglycerides, HDL-C, LDL-C, atherogenic index, fasting blood glucose, plasma glucose area under the curve, serum angiotensin-converting enzyme (ACE), oxidative stress status, histology, and protein expression of PPAR-γ, TNF-α, and NF-κB in adipose tissues were determined. MME improved body weight gain, adiposity index, glucose intolerance, lipid profiles, atherogenic index, ACE, oxidative stress status, and protein expression of TNF-α and NF-κB. Moreover, MME attenuated adipocyte hypertrophy and enhanced PPAR-γ expression. Taken altogether, MME decreased metabolic syndrome and its complication via the increased PPAR-γ expression. Therefore, MME is the potential candidate for improving metabolic syndrome and its related complications. However, further research in clinical trial is still necessary.

Phytoestrogenic Effects of Blackcurrant Anthocyanins Increased Endothelial Nitric Oxide Synthase (eNOS) Expression in Human Endothelial Cells and Ovariectomized Rats.

Phytoestrogens are plant-derived chemicals that are found in many foods and have estrogenic activity. We previously showed that blackcurrant extract (BCE) and anthocyanins have phytoestrogenic activity mediated via estrogen receptors (ERs), and anthocyanins may improve vascular function. BCE contains high levels of anthocyanins, but their health-promoting effects are unclear. This study examined the effects of BCE on the regulation of endothelial nitric oxide synthase (eNOS) expression and nitric oxide (NO) synthesis in human endothelial cells as key regulators in cardiovascular disease. The results showed that eNOS mRNA levels were significantly upregulated in BCE- or anthocyanin-treated human vascular endothelial cells but decreased in cells treated with fulvestrant, an ER antagonist. These results corresponded with NO levels, suggesting that BCE and anthocyanin may regulate NO synthesis via eNOS expression. Thus, the phytoestrogenic effects exerted by BCE via ERs influenced eNOS mRNA expression and NO synthesis. In vivo, we investigated whether anthocyanin-rich BCE upregulated eNOS protein expression in ovariectomized (OVX) rats, a widely used animal model of menopause. Our results showed that anthocyanin-rich BCE significantly upregulated eNOS mRNA levels and NO synthesis through phytoestrogenic activity and therefore promoted blood vessel health in OVX rats as a postmenopausal model.

Estrogen Receptor Regulation of the Heart in an Animal Model of Menopause

Preclinical studies support the protective effects of estrogens against cardiovascular disease; however, hormone replacement therapy trials are inconsistent. One hypothesis for these discrepancies are the differences in therapy timing. Interestingly no study has examined the chronological myocardial changes associated with menopause. This study is the first to identify changes in estrogen receptor (ER) regulation of the heart using a unique mouse model involving gradual ovarian failure to capture peri-menopause.

Vitamin D-restricted high-fat diet down-regulates expression of intestinal alkaline phosphatase isozymes in ovariectomized rats

Intestinal alkaline phosphatase (IAP) is expressed at a high concentration in the brush border membrane of intestinal epithelial cells. Intestinal alkaline phosphatase controls bacterial endotoxin-induced inflammation by dephosphorylating lipopolysaccharide and is a gut mucosal defense factor. Previously, we reported that IAP activity in the duodenum was significantly decreased in male rats receiving a high-fat diet with vitamin D restriction. Here, we tested the hypothesis that IAP is also regulated by a vitamin D-restricted high-fat diet in an animal model of menopause. Twenty-four female rats were ovariectomized (OVX), and another 6 female rats were sham operated. The OVX rats were divided into 4 groups and fed experimental diets: a basic control diet, a basic control diet with vitamin D restriction, a high-fat diet, and a high-fat diet with vitamin D restriction. After 28days of the experimental diets, the vitamin D-restricted high-fat diet decreased alkaline phosphatase activity in the duodenum of the OVX groups. The vitamin D-restricted high-fat diet down-regulated mRNA expressions of IAP isozymes in the duodenum of the OVX groups. These findings support the hypothesis that the expression of IAP is suppressed by a vitamin D-restricted high-fat diet in OVX rats. An adequate vitamin D intake and prevention of low vitamin D levels may be important for IAP expression in gut homeostasis.

Phytoestrogen coumestrol improves mitochondrial activity and decreases oxidative stress in the brain of ovariectomized Wistar-Han rats

After the cessation of estradiol (E2) production by the ovaries, mitochondrial function is affected in several organs, as demonstrated in animal models of menopause. Coumestrol is a phytocompound belonging to the coumestan family, showing higher binding affinity for estrogen receptors beta (ERβ) and stronger estrogenic activity. The objective of this work was to compare, for the first time, the effects of coumestrol with E2 regarding brain and liver mitochondrial function in 16-week old ovariectomized Wistar-Han rats (OVX rats). OVX animals were treated with a single administration of 30μg/kg E2 or coumestrol for 24h, and mitochondrial function and oxidative stress endpoints were analysed in brain and liver fractions. Obtained results in this study demonstrated that coumesterol is able to improve mitochondrial function in a rodent model with low estrogen levels, most likely due to its modulating effect on mitochondrial respiration and oxidative stress.

Steroidogenic effect of Erxian decoction for relieving menopause via the p-Akt/PKB pathway in vitro and in vivo

Ethnopharmacological relevanceErxian decoction (EXD), an empirical Chinese medicine formula, is effectively used in the clinical treatment of menopause-related symptoms in China. Previous data from our group show that EXD has steroidogenic effect on natural menopausal Sprague–Dawley-rats (SD-rats) as an animal model of menopause. However, the mechanistic studies on steroidogenic effects of EXD are still inadequate. Hence, the mechanisms of steroidogenic effects of EXD were studied in vitro and in vivo in this study. Materials and methodsMenopause causes a decline of endocrine function and a series of symptoms. In this study, 16–20-month-old female SD rats with a low serum estradiol level were employed. Their endocrine functions after treatment with EXD (4.1g/kg) were assessed by determination of their serum estradiol level. Proteins involved in the steroidogenic pathway including StAR, 17βHSD, 3βHSD, aromatase, and activation of phosphorylated Protein Kinase B (p-Akt/PKB), as well as estradiol receptor proteins (ERα & ERβ) after EXD treatment were analyzed. Kinase inhibition assay was conducted to confirm the mechanism of steroidogenic effects of EXD in vitro. MCF-7 and BT-483 cells were used to investigate whether EXD stimulated breast cancer cell proliferation. ResultsResults revealed a significantly ameliorated serum estradiol level, and a significantly increased expression of ovarian aromatase and PKB in the EXD-treated rats. EXD attenuated 17β-estradiol stimulated proliferation of breast cancer cells. ConclusionsThe results obtained from immunoblotting and measurements of serum estradiol level of the present investigation revealed that EXD may relieve the menopausal syndrome through an upregulation of ovarian aromatase and p-PKB expression without stimulating the growth of breast cancer cells.

Ovariectomy results in inbred strain-specific increases in anxiety-like behavior in mice

Women are at an increased risk for developing affective disorders during times of hormonal flux, including menopause when the ovaries cease production of estrogen. However, while all women undergo menopause, not all develop an affective disorder. Increased vulnerability can result from genetic predisposition, environmental factors and gene by environment interactions.In order to investigate interactions between genetic background and estrogen depletion, we performed bilateral ovariectomy, a surgical procedure that results in estrogen depletion and is thought to model the post-menopausal state, in a genetically defined panel of 37 inbred mouse strains. Seventeen days post-ovariectomy, we assessed behavior in two standard rodent assays of anxiety- and depressive-like behavior, the open field and forced swim tests.We detected a significant interaction between ovariectomy and genetic background on anxiety-like behavior in the open field. No strain specific effects of ovariectomy were observed in the forced swim assay. However, we did observe significant strain effects for all behaviors in both the open field and forced swim tests.This study is the largest to date to look at the effects of ovariectomy on behavior and provides evidence that ovariectomy interacts with genetic background to alter anxiety-like behavior in an animal model of menopause.

Estradiol Valerate and Remifemin ameliorate ovariectomy-induced decrease in a serotonin dorsal raphe–preoptic hypothalamus pathway in rats

Perimenopausal syndromes begin as ovarian function ceases and the most common symptoms are hot flushes. Data indicate that the projections of serotonin to hypothalamus may be involved in the mechanism of hot flushes. Therefore, the aim of this study is to investigate the potential role of the serotonin dorsal raphe–preoptic hypothalamus pathway for hot flushes in an animal model of menopause. We determined the changes in serotonin expression in the dorsal raphe (DR) and preoptic anterior hypothalamus (POAH) in ovariectomized rats. We also explored the therapeutical effects of estradiol valerate and Remifemin in this model. Eighty female Sprague-Dawley rats were randomly assigned to sham-operated (SHAM) group, ovariectomy (OVX) group with vehicle, ovariectomy with estradiol valerate treatment (OVX+E) group and ovariectomy with Remifemin (OVX+ICR) group. Serotonin expression was evaluated in the DR and POAH using immunofluorescence and quantified in the DR using an enzyme-linked immunosorbent assay (ELISA). Apoptosis was analyzed in the DR by TUNEL assay. The number of serotonin immunoreactive neurons and the level of serotonin expression in the DR decreased significantly following OVX compared to the SHAM group. No TUNEL-positive cells were detected in the DR in any group. In addition, following OVX, the number of serotonin-positive fibers decreased significantly in the ventromedial preoptic nucleus (VMPO), especially in the ventrolateral preoptic nucleus (VLPO). Treatment with either estradiol or Remifemin for 4 weeks countered the OVX-induced decreases in serotonin levels in both the DR and the hypothalamus, with levels in the treated rats similar to those in the SHAM group. A fluorescently labeled retrograde tracer was injected into the VLPO at the 4-week time point. A significantly lower percentage of serotonin with CTB double-labeled neurons in CTB-labeled neurons was demonstrated after ovariectomy, and both estradiol and Remifemin countered this OVX-induced decrease. We conclude that serotonin pathway is changed after ovariectomy, including the serotonin synthesis in DR and serotonin fibers in PO/AH, both E and Remifemin have an equivalent therapeutic effect on it.

Saccharin induces alterations in sugar homeostasis as assessed with an animal model of menopause

O is currently considered a pandemic, worldwide, and finding ways to reduce its incidence has become a paramount objective of health-policies in many countries. Limiting the number of ingested calories is a strategy that has shown beneficial to reduce the prevalence of obesity. With this in mind, the use of artificial sweeteners is often advised in order to reduce the amount of ingested calories. Other studies would, however, pose caution on the use of artificial sweeteners, which would have been shown to be able to induce glucose intolerance, one of the landmarks of obesity and diabetes, in animal models and humans. Indeed, artificial sweeteners would, themselves, have been proposed as main contributors to the spread of obesity worldwide. But still, research is needed to clarify the role played by these compounds in the obesity problem. In menopausal women, obesity has been found to be an important risk factor for the development of postmenopausal breast cancer, and replacing caloric beverages with diet beverages, usually, artificially sweetened, continues to be a mainstream strategy in weight control in adult and peri-menopausal women. Unfortunately, to date, little is known about the effects of artificial sweeteners on weight gain or metabolic control in menopausal women. For this reason, we decided to assess the possible impact of the common artificial sweetener, saccharin, in an animal model of menopause, namely, the ovarectomized mouse. To this end, we selected 12 female ovarectomized C57BL/6 mice and assessed their metabolic control with a glucose tolerance test. Then, they were offered a 0.1% saccharin in water solution at their home cages for 16 days, after what, the glucose tolerance test was repeated. We found significant differences (p<0.005 and p<0.05) in basal glucose levels of the animals, after the 16 hour fasting preceding the glucose tolerance test posterior to the 16d saccharin treatment and these differences lasted for at least 45 days. Further studies should explore the importance of the observed alterations in the development of obesity and its possible role in human postmenopausal health.

Anti-aging effect of estrogen on telomerase activity in ovariectomised rats – animal model for menopause

Objective: The aim of this study was to investigate the anti-aging effects of exogenous estrogen on telomerase activity in ovariectomized female Sprague-Dawley rats.Methods: Thirty-three 12-week-old female rats were divided into three groups: the ovariectomized-Treated group (Treated, n = 11), the ovariectomized control group (OVX, n = 11) and the Sham-operated group (Sham, n = 11). The rats in the Treated group were given 0.21 mg/kg estradiol valerate intragastric administration while other two groups were given the amount of physiological saline daily. All of the animals were euthanized 12 weeks after treatment, and abdominal aortic blood samples were taken to assess the level of estradiol (E2), follicle stimulating hormone (FSH). Telomerase activity and telomerase reverse transcriptase (TERT) mRNA expression in the heart, liver, brain tissues of all rats were measured by reverse transcriptional polymerase chain reaction (RT-PCR) and competitive enzyme-linked immunosorbent assay (ELISA).Results: Compared to the OVX and Sham group, telomerase activity and TERT mRNA levels were significantly increased in the heart, liver and brain tissues of rats in the Treated group (p < 0.05). The telomerase expression was significantly higher in the heart than in liver and brain tissues in the Treated group (p < 0.05).Conclusion: Based on the findings in the ovariectomized female rats model, exogenous estrogen can significantly up-regulate telomerase activity and TERT mRNA expression to exert the effects of anti-aging.

Hippocampal Gene Expression Is Highly Responsive to Estradiol Replacement in Middle-Aged Female Rats.

In the hippocampus, estrogens are powerful modulators of neurotransmission, synaptic plasticity and neurogenesis. In women, menopause is associated with increased risk of memory disturbances, which can be attenuated by timely estrogen therapy. In animal models of menopause, 17β-estradiol (E2) replacement improves hippocampus-dependent spatial memory. Here, we explored the effect of E2 replacement on hippocampal gene expression in a rat menopause model. Middle-aged ovariectomized female rats were treated continuously for 29 days with E2, and then, the hippocampal transcriptome was investigated with Affymetrix expression arrays. Microarray data were analyzed by Bioconductor packages and web-based softwares, and verified with quantitative PCR. At standard fold change selection criterion, 156 genes responded to E2. All alterations but 4 were transcriptional activation. Robust activation (fold change > 10) occurred in the case of transthyretin, klotho, claudin 2, prolactin receptor, ectodin, coagulation factor V, Igf2, Igfbp2, and sodium/sulfate symporter. Classification of the 156 genes revealed major groups, including signaling (35 genes), metabolism (31 genes), extracellular matrix (17 genes), and transcription (16 genes). We selected 33 genes for further studies, and all changes were confirmed by real-time PCR. The results suggest that E2 promotes retinoid, growth factor, homeoprotein, neurohormone, and neurotransmitter signaling, changes metabolism, extracellular matrix composition, and transcription, and induces protective mechanisms via genomic effects. We propose that these mechanisms contribute to effects of E2 on neurogenesis, neural plasticity, and memory functions. Our findings provide further support for the rationale to develop safe estrogen receptor ligands for the maintenance of cognitive performance in postmenopausal women.

Baroreflex sensitivity and central hemodynamics after omega-3 polyunsaturated fatty acids supplementation in an animal model of menopause

ObjectiveBaroreflex sensitivity (BRS) and central arterial function are significantly worsened after menopausal transition. This study tested the hypothesis that administration of n-3 polyunsaturated fatty acids (n-3 PUFA) might contribute to prevent these adverse changes in the vascular function of ovariectomized rats, an animal model of experimental menopause. MethodsWe randomized 30 female Wistar rats, 2months old, into 3 groups: control (CTRL), sham surgery, normal diet; ovariectomized with normal diet (OVX) and ovariectomized with n-3 PUFA supplementation by daily gavage (0.8g/kg/d) (OVX+O3). Two months after surgery, BRS was calculated as the bradycardic response to phenylephrine-induced blood pressure increase, while large artery function was estimated by the graphical analysis of the aortic pressure wave (diastolic to systolic pressure-time integral ratio, DTI/STI). ResultsOvariectomy caused a significant decrease in BRS (CTRL: 6.23±0.68ms/mmHg; OVX: 2.85±0.75; p<0.001). n-3 PUFA supplementation prevented part of the decline of BRS caused by surgical menopause (OVX+O3: 4.75±0.53; p<0.01 vs OVX). In animals treated with n-3 PUFA, the central arterial pressure profile did not show the changes in DTI/STI ratio seen in OVX (OVX: 3.31±1.72; OVX+O3: 3.83±1.52; p<0.01). ConclusionsIn an experimental model of menopause, treatment with n-3 PUFA normalized central hemodynamics and prevented the decrease in BRS, associated with the reduction of compliance of the arterial wall. These findings suggest a therapeutic benefit of n-3 PUFA supplementation in the prevention of postmenopausal vascular disease.