Dysfunction In Ovariectomized Rats Research Articles

Effect of deferoxamine and ferrostatin-1 on salivary gland dysfunction in ovariectomized rats.

The mechanism underlying xerostomia after menopause has not yet been fully elucidated. This study aimed to investigate the mechanism of xerostomia and the effect of the ferroptosis inhibitors deferoxamine (DFO) and ferrostatin-1 (FER) on salivary gland dysfunction in a postmenopausal animal model. Twenty-four female Sprague-Dawley rats were randomly divided into four groups: a SHAM group (n = 6, sham-operated rats), an OVX group (n = 6, ovariectomized rats), an FER group (n = 6, ovariectomized rats injected intraperitoneally with FER), and a DFO group (n = 6, ovariectomized rats injected intraperitoneally with DFO). GPX4 activity, iron accumulation, lipid peroxidation, inflammation, fibrosis, and salivary gland function were analyzed. Recovery of GPX4 activity and a decrease in iron accumulation and cytosolic MDA + HAE were observed in the DFO group. In addition, collagen I, collagen III, TGF-β, IL-6, TNF-α, and TGF-β levels were decreased in the DFO group compared to the OVX group. Recovery of GPX4 activity and the morphology of mitochondria, and reduction of cytosolic MDA + HAE were also observed in the FER group. In addition, decreased expression of inflammatory cytokines and fibrosis markers and increased expression of AQP5 were observed in both the DFO and FER groups. Postmenopausal salivary gland dysfunction is associated with ferroptosis, and DFO and FER may reverse the postmenopausal salivary gland dysfunction after menopause. DFO and FER are hence considered promising treatments for postmenopausal xerostomia.

Ellagic acid prevents myocardial infarction-induced left ventricular diastolic dysfunction in ovariectomized rats

Estrogen deficiency is associated with increased oxidative stress, which can contribute to left ventricular diastolic dysfunction (LVDD). We hypothesized that oral treatment with ellagic acid (EA), a potent and natural antioxidant compound, can improve MI-induced LVDD in ovariectomized rats, by reducing the formation of reactive oxygen species. Ovariectomized rats MI-induced LVDD followed by treatment with vehicle (DD) or EA (DD + EA) for 4 weeks. Non-LVDD-induced rats treated with vehicle (S) or EA (S + EA) were used as controls. Left ventricular systolic pressure; left ventricular end-diastolic pressure (LVEDP); maximum rate of pressure rise: +dP/dt and fall: –dP/dt) were evaluated in all animals after treatment. Left ventricle superoxide anion formation was quantified in situ by fluorescence. Phospho-CAMKII, SOD2, catalase, and gp91-phox abundances were evaluated by Western blot analyses. SOD (superoxide dismutase) and catalase activities were measured by spectrophotometry. The results showed that the LVEDP was significantly increased in both DD and DD + EA groups compared to S and S + EA. However, LVEDP in the DD + EA group was significantly decreased compared to DD, indicating an EA-mediated effect. In the DD group, superoxide production and gp91-phox protein abundance were increased while SOD2 abundance was decreased when compared to the S and S + EA groups. An increase in SOD activity was also observed in the DD + EA group. EA treatment reduced CaMKII phosphorylation in the DD + EA group compared to the DD. We concluded that EA treatment attenuated diastolic dysfunction in our experimental model, via reduction of reactive oxygen species and CaMKII activity, indicating EA as a promising natural therapeutic option for cardiac dysfunction.

Tonsil mesenchymal stem cells-derived extracellular vesicles prevent submandibular gland dysfunction in ovariectomized rats.

Dry mouth that occurs after menopause significantly reduces the quality of life of the elderly. The extracellular vesicles derived from mesenchymal stem cells are being studied for application in various pathological conditions in the field of tissue regenerative medicine. This study is to investigate the therapeutic effect on salivary gland dysfunction occurring after ovariectomy using tonsil mesenchymal stem cells (T-MSCs)-derived extracellular vesicles. The rats were divided into the following groups: sham-operated rats (SHAM), rats that underwent ovariectomy (OVX), and rats that underwent OVX surgery and were simultaneously injected with T-MSC-derived extracellular vesicles (OVX+EV). The rats were sacrificed 6 weeks after ovariectomy. Estradiol levels decreased in the OVX group compared with those in the SHAM group. Extracellular vesicles had no effect on estradiol levels or estrogen receptor β expression. The evaluation of pro-inflammatory cytokines, TNF-α and IL-6, increased in the OVX group and decreased in the OVX+EV group. The expressions of collagen I and TGFβI increased in the OVX group but decreased in the OVX+EV group. Moreover, to examine submandibular gland function, AQP5 and α-amylase expressions were downregulated in the OVX group, but improved upon exosome injection. In conclusion, T-MSC-derived extracellular vesicles are useful for the prevented submandibular gland dysfunction that occurs after menopause.

Progesterone eliminates 17β-estradiol-Mediated cardioprotection against diabetic cardiovascular dysfunction in ovariectomized rats

BackgroundType2 Diabetes (T2D) remains one of the most important causes of cardiovascular diseases (CVD). Menopause leads to an increase in CVD and metabolic syndrome, which indicates the role of sex steroids as a protective factor. In the present study, we surveyed the effects of 17β-estradiol (E2) alone and in combination with progesterone (P4) on cardiovascular dysfunction in T2D. MethodsFemale ovariectomized (OVX) diabetic rats were divided into eight groups: Sham-Control, Diabetes (Dia), OVX + Dia, OVX + Dia + Vehicle, OVX + Dia + E2, OVX + Dia + P4, OVX + Dia + E2+P4, and OVX + Dia + E2+Vehicle. T2D was induced by a high-fat diet and streptozotocin. E2 and P4 were administrated every four days for four weeks. The heart cytokines and angiotensin II, lipid profile, insulin, water, and food intake and cardiovascular indices were measured. ResultsResults showed that single treatment with E2 decreased fasting blood glucose, water, and food intake, atherogenic and cardiac risk indices, and blood pressure. Also, P4 led to a decrease in atherogenic and cardiac risk indices. TNFα and IL-6 levels were increased and IL-10 was decreased in the Dia group, while E2 alone was able to inhibit these changes. The combined use of E2 and P4 eliminated the beneficial effects of E2 on these indices. Although diabetes results in an increment of cholesterol, LDL and triglyceride, hormone therapy with E2 was associated with improved dyslipidemia. ConclusionThe use of E2 alone, and not the individual use of P4, and its combination with E2 improved cardiovascular function in OVX diabetic animals, possibly by reducing the amount of inflammatory cytokines and improving metabolic parameters.

Effects of oligonol on the submandibular gland in ovariectomized rats

The aim of this study was to observe the effects of oligonol on submandibular gland dysfunction in ovariectomized rats. We randomly divided female Sprague-Dawley rats into sham-operated, ovariectomized, and oligonol-treated ovariectomized groups. Oligonol was intraperitoneally administered at 30 mg/kg daily for six weeks. Lipogenesis increased after the ovariectomy while fatty acid oxidation increased and intracellular triglyceride levels decreased in response to oligonol treatment. Submandibular gland fibrosis characterized by collagen type I accumulation was observed in the ovariectomized group. However, oligonol markedly reduced fibrosis to a level comparable to that observed in the sham group. Aquaporin 1 and glucose transporter 4 were downregulated in the ovariectomized group. Nevertheless, both factors were significantly upregulated by oligonol treatment. However, aquaporin 5 was significantly downregulated in the oligonol treatment group. Our findings indicate that oligonol protects against damage in postmenopausal rat salivary glands.

Construction of time-response curve for neuronal and vascular endothelial dysfunction in ovariectomized rats

BACKGROUND:Studies have shown that there is a critical time period to start hormone therapy after the loss of ovarian function during menopause. The length of estrogen deprivation may evolve different pathophysiological manifestations.OBJECTIVE:The aim of the present study was to investigate behavioral, biochemical, and molecular alterations at different time points after surgical menopause with an aim and identify various pathophysiological targets to exploit “window of opportunity” and to design newer therapeutic modalities for menopause-associated neurobehavioral and vascular deficits.MATERIALS AND METHODS:Bilateral ovariectomy was performed to induce surgical menopause and estrogen deficiency state. Menopause-associated neuronal and vascular dysfunctions were noted after 1, 2, and 3 months of the study.RESULTS:Neuronal and vascular endothelial dysfunction post ovariectomy revealed that behavioral, biochemical, molecular, and vascular endothelial dysfunction appeared after 1 month of ovariectomy except hyperglycemia, which occurs after 3 months.CONCLUSIONS:Time-response studies measuring behavioral, biochemical, and molecular markers at various time points after ovariectomy reveal that there is a fast onset of neuronal and vascular complications, but the duration of insulin resistance is a relatively late phenomenon.

Activation of autophagy is involved in the protective effect of 17β-oestradiol on endotoxaemia-induced multiple organ dysfunction in ovariectomized rats.

Oestrogens have been reported to attenuate acute inflammation in sepsis. In this study, the effects of long‐term oestrogen replacement with 17β‐oestradiol (E2) on endotoxaemia‐induced circulatory dysfunction and multiple organ dysfunction syndrome were evaluated in ovariectomized (Ovx) rats. E2 (50 μg/kg, s.c., 3 times/week) was administered for 8 weeks, followed by the induction of endotoxaemia by intravenous infusion of lipopolysaccharides (LPS; 30 mg/kg/4 hrs). Oestrogen deficiency induced by ovariectomy for 9 weeks augmented the LPS‐induced damage, including endotoxic shock, myocardial contractile dysfunction, renal dysfunction and rhabdomyolysis. Cardiac levels of NF‐κB p65, iNOS and oxidized glutathione, free radical production in skeletal muscles, myoglobin deposition in renal tubules, and plasma levels of plasminogen activator inhibitor‐1, TNF‐α, and IL‐6 were more pronounced in the Ovx + LPS group than in the Sham + LPS group. Long‐term treatment of E2 prevented this amplified damage in Ovx rats. Six hours after LPS initiation, activation of the autophagic process, demonstrated by increases in Atg12 and LC3B‐II/LC3B‐I ratios, and induction of haem oxygenase (HO)‐1 and heat‐shock protein (HSP) 70 protein expression in myocardium were increased significantly in the Ovx + E2 + LPS group. These results suggest that activation of autophagy and induction of HO‐1 and HSP70 contribute to the protective effect of long‐term E2 replacement on multiple organ dysfunction syndrome in endotoxaemia.

The impact of exogenous estrogens on biochemical markers of endothelial dysfunction in diabetic rats with hypoestrogenia

It was investigated the impact of selective estrogen receptor modulator PE0607 comparing to 17β-estradiol on the biochemical markers of endothelial dysfunction in ovariectomized rats with type 2 diabetes. It was established that injection of PE0607 as well as 17β-estradiol decreases lipid peroxidation first products in serum and increases serum whole antioxidant activity and NO-synthase activity in vessels of experimental rats. These results justify the perspectives of compound PE0607 use as a potential gender-specific agent for prevention and treatment of diabetic cardiovascular disorders in women with hypoestrogenia.

Metformin ameliorates ovariectomy-induced vascular dysfunction in non-diabetic Wistar rats

Metformin is an antihyperglycaemic drug with pleiotropic effects that result in cardiovascular improvement. The aim of the present study was to evaluate the effects of metformin treatment on vascular dysfunction in ovariectomized rats. At 8 weeks of age, female Wistar rats were subjected to ovariectomy or a sham surgery. After 21 days, the animals were divided into three groups: SHAM (sham-operated rats), OVX (ovariectomized rats) and MET (ovariectomized rats treated with metformin at 300 mg/kg of body weight per day), and treated for 14 days. The vasorelaxation responses to ACh (acetylcholine) and SNP (sodium nitroprusside) were evaluated in mesenteric vascular beds, oxidative stress was evaluated and Western blot analysis of eNOS (endothelial NO synthase) and the NADPH oxidase Nox2 was performed. ACh-induced relaxation was reduced in the OVX group and partially restored in the MET group. L-NAME (NG-nitro-L-arginine methyl ester) attenuated and equalized the ACh-induced response in all groups. Attenuation of the ACh-induced responses by 4-aminopyridine (a blocker of voltage-gated potassium channels) was greater in the MET group compared with the OVX group. The SNP-induced responses were reduced in the OVX group and restored in the MET group. Inhibition of NADPH oxidase by apocynin (10 μM) restored the SNP-induced responses in the OVX group, enhanced these responses in the MET group and had no effect in the SHAM group. The OVX group exhibited reduced levels of eNOS protein and increased levels of oxidative stress and Nox2 protein; metformin treatment corrected all of these parameters. In conclusion, the pathophysiological changes observed in the mesenteric beds of ovariectomized rats were ameliorated by metformin. If this translates to humans, metformin could have additional benefits for post-menopausal women treated with this drug for glycaemic control.

Dehydroepiandrosterone protects against oxidative stress‐induced endothelial dysfunction in ovariectomized rats

Cardiovascular disease is less frequent in premenopausal women than in age-matched men or postmenopausal women. Moreover, the marked age-related decline in serum dehydroepiandrosterone (DHEA) level has been associated to cardiovascular disease. The aim of this study was to evaluate the effects of DHEA treatment on vascular function in ovariectomized rats. At 8 weeks of age, female Wistar rats were ovariectomized (OVX) or sham (SHAM) operated and 8 weeks after surgery both groups were treated with vehicle or DHEA (10mg kg⁻¹ week⁻¹) for 3 weeks. Aortic rings were used to evaluate the vasoconstrictor response to phenylephrine (PHE) and the relaxation responses to acetylcholine (ACh) and sodium nitroprusside (SNP). Tissue reactive oxygen species (ROS) production and SOD, NADPH oxidase and eNOS protein expression were analysed. PHE-induced contraction was increased in aortic rings from OVX compared to SHAM, associated with a reduction in NO bioavailability. Furthermore, the relaxation induced by ACh was reduced in arteries from OVX, while SNP relaxation did not change. The incubation of aortic rings with SOD or apocynin restored the enhanced PHE-contraction and the impaired ACh-relaxation only in OVX. DHEA treatment corrected the increased PHE contraction and the impaired ACh-induced relaxation observed in OVX by an increment in NO bioavailability and decrease in ROS production. Besides, DHEA treatment restores the reduced Cu/Zn-SOD protein expression and eNOS phosphorylation and the increased NADPH oxidase protein expression in the aorta of OVX rats. The present results suggest an important action of DHEA, improving endothelial function in OVX rats by acting as an antioxidant and enhancing the NO bioavailability.

Tumor necrosis factor‐alpha antagonist administration recovers skeletal muscle dysfunction in ovariectomized rats

Skeletal muscles deteriorate after ovariectomy. Molecular pathway of this deterioration has not been defined. Tumor necrosis factor (TNF)-alpha activation is assumed to trigger muscle atrophy and administration of its antagonist is hypothesized to recover this atrophy in rats. Slow-twitch soleus and fast-twitch extensor digitorum longus muscle functions were investigated in intact, ovariectomized (OVX), and OVX plus 10 µg/g/week TNF-alpha antagonist administered female rats. Maximum isometric twitch and tetanic contraction responses were lower in the OVX groups. Maximum isometric twitch amplitudes recovered in the extensor digitorum longus but not in the soleus muscles after TNF-alpha antagonist administration. The decrease in responses to tetanic stimulations recovered in the OVX-TNF group at frequencies higher than 20 Hz in both muscle types. OVX animals body weight was 21% higher than intact animals. Muscle weight to body weight ratios of the OVX groups were higher than the control group which recovered after TNF-alpha antagonist administration. Findings suggest that the functional loss in OVX rat muscles is TNF-alpha pathway dependent. Skeletal muscle atrophy and function after OVX recovered by TNF-alpha antagonist administration.

Effects of exercise training on autonomic dysfunction management in an experimental model of menopause and myocardial infarction

The aim of this study was to investigate the effects of exercise training on cardiovascular autonomic dysfunction in ovariectomized rats submitted to myocardial infarction. Female Wistar rats were divided into the following ovariectomized groups: sedentary ovariectomized (SO), trained ovariectomized (TO), sedentary ovariectomized infarcted (SOI), and trained ovariectomized infarcted (TOI). Trained groups were submitted to an exercise training protocol on a treadmill (8 wk). Arterial baroreflex sensitivity was evaluated by heart rate responses to arterial pressure changes, and cardiopulmonary baroreflex sensitivity was tested by bradycardic and hypotension responses to serotonin injection. Vagal and sympathetic effects were calculated by pharmacological blockade. Arterial pressure was reduced in the TO in comparison with the SO group and increased in the TOI in relation to the SOI group. Exercise training improved the baroreflex sensitivity in both the TO and TOI groups. The TOI group displayed improvement in cardiopulmonary reflex sensitivity compared with the SOI group at the 16 microg/kg serotonin dose. Exercise training enhanced the vagal effect in both the TO (45%) and TOI (46%) animals compared with the SO and SOI animals and reduced the sympathetic effect in the TOI (38%) in comparison with the SOI animals. Significant correlations were obtained between bradycardic baroreflex responses and vagal (r = -0.7, P < 0.005) and sympathetic (r = 0.7, P < 0.001) effects. These results indicate that exercise training in ovariectomized rats submitted to myocardial infarction improves resting hemodynamic status and reflex control of the circulation, which may be due to an increase in the vagal component. This suggests a homeostatic role for exercise training in reducing the autonomic impairment of myocardial infarction in postmenopausal women.

The influence of ovariectomy and estrogen replacement on voiding patterns and detrusor muscarinic receptor affinity in the rat

A rat model of ovariectomy-induced voiding dysfunction was established and the effects of ovariectomy and subsequent estrogen replacement on the affinity of muscarinic receptors in the rat bladder were determined. Voiding frequency and spatial distribution patterns were documented in sham-operated (control), and ovariectomized (placebo- or estrogen-treated) rats. The ovariectomized rats had a significantly different urinating pattern, i.e. higher voiding frequency and less peripheral voiding than the sham-operated group, suggestive of urge incontinence. Using this model of voiding dysfunction, negative logs of dissociation constants of carbachol of the rat detrusor muscarinic receptors were then determined indirectly using the Furchgott's double-reciprocal method. Receptor affinities were not significantly different in all groups compared to control females. In conclusion, a model of ovariectomy-induced voiding dysfunction in ovariectomized rats was established, where bladder dysfunction occurred with no significant changes in the affinity of muscarinic receptors.

The effect of the phytoestrogen genistein on plasma nitric oxide concentrations, endothelin-1 levels and endothelium dependent vasodilation in postmenopausal women

The phytoestrogen genistein improves endothelial dysfunction in ovariectomized rats through a nitric oxide-dependent mechanism. We investigated whether genistein alters the balance between the nitric oxide products and endothelin-1 and influences endothelium-dependent vasodilation in postmenopausal women. Sixty healthy postmenopausal women were enrolled in the study. A double-blind, placebo controlled, randomized design was employed. After a 4-week stabilization on a standard fat-reduced diet, participants to the study were randomly assigned to receive either genistein ( n=30; 54 mg/day) or placebo ( n=30). Flow-mediated, endothelium-dependent vasodilation of the brachial artery, plasma nitric oxide breakdown products and endothelin-1 levels were measured at baseline and after 6 months of genistein therapy. The mean baseline level of nitrites/nitrates was 22±10 μmol/l and increased to 41±10 μmol/ml after 6 months of treatment. The mean baseline plasma endothelin-1 level was 14±4 pg/ml and decreased to 7±1 pg/ml following 6 months of treatment with genistein. The mean baseline ratio of nitric oxide to endothelin also significantly increased at the end of treatment. Flow-mediated, endothelium-dependent vasodilation of the brachial artery was 3.9±0.8 mm at baseline and increased to 4.4±0.7 mm after 6 months of treatment. Placebo-treated women showed no changes in plasma nitrites/nitrates, endothelin-1 levels and flow-mediated vasodilation. Genistein therapy improves flow-mediated endothelium dependent vasodilation in healthy postmenopausal women. This improvement may be mediated by a direct effect of genistein on the vascular function and could be the result of an increased ratio of nitric oxide to endothelin.

Endothelial dysfunction and oxidative stress during estrogen deficiency in spontaneously hypertensive rats.

Postmenopausal estrogen deficiency is associated with an increased cardiovascular risk, hypertension, and oxidative stress. Angiotensin type 1 (AT(1)) receptor regulation is involved in the pathogenesis of atherosclerosis. To characterize vascular function, oxidative stress, and AT(1) receptor regulation during estrogen deficiency, ovariectomized spontaneously hypertensive rats (SHR) were investigated in comparison with sham-operated animals and with ovariectomized rats receiving estrogen replacement therapy with 17beta-estradiol. Arterial blood pressure was similar in all 3 groups investigated. Five weeks after ovariectomy, endothelial dysfunction in aortic rings was observed, which was reversed by estrogen replacement therapy. Estrogen deficiency led to an enhanced vasoconstriction by angiotensin II. Vascular superoxide production was significantly increased compared with that in sham-operated rats, as measured by lucigenin chemiluminescence assays. Estrogen substitution normalized the production of free radicals in the vessel wall. Vascular AT(1) receptor expression was significantly upregulated by estrogen deficiency, as shown by quantitative reverse transcription-polymerase chain reaction, whereas endothelial NO synthase mRNA expression and NO release were unchanged. Five-week treatment of the animals with the AT(1) receptor antagonist irbesartan prevented endothelial dysfunction in ovariectomized rats and normalized the vascular production of free radicals. In SHR, estrogen deficiency leads to increased vascular free radical production and enhanced angiotensin II-induced vasoconstriction via increased vascular AT(1) receptor expression, resulting in endothelial dysfunction. Estrogen replacement therapy and AT(1) receptor antagonism prevent these pathological changes. Therefore, estrogen deficiency-induced AT(1) receptor overexpression and oxidative stress may play an important role in cardiovascular diseases associated with menopause.