Aging is associated with loss of beneficial effects of estrogen on leptin responsiveness in mice fed high fat diet: Role of estrogen receptor α and cytokines

Caloric and time restriction diets improve acute kidney injury in experimental menopausal rats: role of silent information regulator 2 homolog 1 and transforming growth factor beta 1

BACKGROUND

Estrogen has a protective impact on acute kidney injury (AKI); moreover, reducing the daily intake of calories impedes developing diseases. The present study aimed to determine the effects of calorie restriction (CR) and time restriction (TR) diets on the expression of silent information regulator 2 homolog 1 (SIRT1), transforming growth factor beta 1 (TGF-β1), and other indicators in the presence and absence of ovaries in AKI female rats.

METHODS

The female rats were divided into two groups, ovariectomized (OVX) and sham, and were placed on CR and TR diets for eight weeks; afterward, AKI was induced by injecting glycerol, and kidney injury indicators and biochemical parameters were measured before and after AKI.

RESULTS

After AKI, the levels of urine albumin excretion rate, urea, and creatinine in serum, and TGF-β1 increased, while creatinine clearance and SIRT1 decreased in kidney tissue. CR improved kidney indicators and caused a reduction in TGF-β1 and an increase in SIRT1 in ovary-intact rats. Moreover, CR prevented total antioxidant capacity (TAC) decrease and malondialdehyde (MDA) increase resulting from AKI. Before AKI, an increase in body weight, fasting blood sugar (FBS), low-density lipoprotein (LDL), triglyceride (TG), and total cholesterol (TC), and a decrease in high-density lipoprotein (HDL) were observed in OVX rats compared to sham rats, but CR prevented these changes. The effects of TR were similar to those of CR in all indicators except for TGF-β1, SIRT1, urea, creatinine, and albumin.

CONCLUSION

The present study indicated that CR is more effective than TR in preventing AKI, probably by increasing SIRT1 and decreasing TGF-β1 in ovary-intact animals.

Exploratory metabolomic analysis for characterizing the metabolic profile of the urinary bladder under estrogen deprivation

Background

Estrogen homeostasis is crucial for bladder function, and estrogen deprivation resulting from menopause, ovariectomy or ovarian dysfunction may lead to various bladder dysfunctions. However, the specific mechanisms are not fully understood.

Methods

We simulated estrogen deprivation using a rat ovariectomy model and supplemented estrogen through subcutaneous injections. The metabolic characteristics of bladder tissue were analyzed using non-targeted metabolomics, followed by bioinformatics analysis to preliminarily reveal the association between estrogen deprivation and bladder function.

Results

We successfully established a rat model with estrogen deprivation and, through multivariate analysis and validation, identified several promising biomarkers represented by 3, 5-tetradecadiencarnitine, lysoPC (15:0), and cortisol. Furthermore, we explored estrogen deprivation-related metabolic changes in the bladder primarily characterized by amino acid metabolism imbalance.

Conclusion

This study, for the first time, depicts the metabolic landscape of bladder resulting from estrogen deprivation, providing an important experimental basis for future research on bladder dysfunctions caused by menopause.

The role of cognitive function in the relationship between surrogate markers of visceral fat and depressive symptoms in general middle-aged and elderly population: A nationwide population-based study

BACKGROUND

The relationship between obesity and depressive symptoms is well documented, but not visceral fat, especially among Chinese adults are scarce. We aimed to investigate the association between visceral fat and depressive symptoms and the mediation of cognitive function.

METHODS

A total of 19,919 and 5555 participants from the China Health and Retirement Longitudinal Study were enrolled in the cross-sectional and follow-up analyses. Depressive symptoms were measured by the Center of Epidemiological studies depression scale (CES-D). Visceral fat measured by the waist circumference triglyceride (WT) index [calculated as waist circumference (cm)* triglyceride (mmol/L)]. The relationship between the WT index and depressive symptoms was analyzed by binary logistics and Poisson regression. The mediated role of cognitive ability was examined by intermediary analysis.

RESULTS

In the cross-sectional study, higher visceral fat was associated with a lower risk of depressive symptoms. But in the follow-up study, individuals in quintile 2 to quintile 4 of the WT index have a reduced risk of depressive symptoms after four years. Compared with the lower index, quintile 2 of the WT index protected from difficulty concentrating (RR [95%CI]: 0.90 [0.82,0.98], p = 0.023), feeling scared (RR [95%CI]: 0.86 [0.73,0.98], p = 0.030) and feeling that life could not go on (RR [95%CI]: 0.85 [0.74,0.98], p = 0.023). Moreover, cognitive ability explained 11.52 % of the association between visceral fat and depressive symptoms.

CONCLUSIONS

Our findings show that moderate visceral fat was associated with a lower risk of depressive symptoms in middle-aged and older Chinese, partly mediated by cognitive function.

Gut Microbiota and Acylcarnitine Metabolites Connect the Beneficial Association between Estrogen and Lipid Metabolism Disorders in Ovariectomized Mice

Decreased estrogen level is one of the main causes of lipid metabolism disorders and coronary heart disease in women after menopause. Exogenous estradiol benzoate is effective to some extent in alleviating lipid metabolism disorders caused by estrogen deficiency. However, the role of gut microbes in the regulation process is not yet appreciated. The objective of this study was to investigate the effects of estradiol benzoate supplementation on lipid metabolism, gut microbiota, and metabolites in ovariectomized (OVX) mice and to reveal the importance of gut microbes and metabolites in the regulation of lipid metabolism disorders. This study found that high doses of estradiol benzoate supplementation effectively attenuated fat accumulation in OVX mice. There was a significant increase in the expression of genes enriched in hepatic cholesterol metabolism and a concomitant decrease in the expression of genes enriched in unsaturated fatty acid metabolism pathways. Further screening of the gut for characteristic metabolites associated with improved lipid metabolism revealed that estradiol benzoate supplementation influenced major subsets of acylcarnitine metabolites. Ovariectomy significantly increased the abundance of characteristic microbes that are significantly negatively associated with acylcarnitine synthesis, such as Lactobacillus and Eubacterium ruminantium group bacteria, while estradiol benzoate supplementation significantly increased the abundance of characteristic microbes that are significantly positively associated with acylcarnitine synthesis, such as Ileibacterium and Bifidobacterium spp. The use of pseudosterile mice with gut microbial deficiency greatly facilitated the synthesis of acylcarnitine due to estradiol benzoate supplementation and also alleviated lipid metabolism disorders to a greater extent in OVX mice. IMPORTANCE Our findings establish a role for gut microbes in the progression of estrogen deficiency-induced lipid metabolism disorders and reveal key target bacteria that may have the potential to regulate acylcarnitine synthesis. These findings suggest a possible route for the use of microbes or acylcarnitine to regulate disorders of lipid metabolism induced by estrogen deficiency.

Beneficial effects of time and energy restriction diets on the development of experimental acute kidney injury in Rat: Bax/Bcl-2 and histopathological evaluation

People's lifestyles and, especially, their eating habits affect their health and the functioning of the organs in their bodies, including the kidneys. One's diet influences the cells' responses to stressful conditions such as acute kidney injury (AKI). This study aims to determine the preconditioning effects of four different diets: energy restriction (ER) diet, time restriction (TR) eating, intermittent fasting (IF), and high-fat diet (HF) on histopathological indices of the kidney as well as the molecules involved in apoptosis during AKI. Adult male rats underwent ER, TR, IF, and HF diets for eight weeks. Then, AKI was induced, and renal function indices, histopathological indices, and molecules involved in apoptosis were measured. In animals with AKI, urinary albumin excretion, serum urea, creatinine and, Bax/Bcl-2 ratio increased in the kidney, while renal eGFR decreased. ER and TR diets improved renal parameters and prevented an increase in the Bax/Bcl-2 ratio. The IF diet improved renal parameters but had no effect on the Bax/Bcl-2 ratio. On the other hand, the HF diet worsened renal function and increased the Bax/Bcl-2 ratio. Histopathological examination also showed improved kidney conditions in the ER and TR groups and more damage in the HF group. This study demonstrated that ER and TR diets have renoprotective effects on AKI and possibly cause the resistance of kidney cells to damage by reducing the Bax/Bcl-2 ratio and improving apoptotic conditions.

The effects of G protein-coupled receptor 30 (GPR30) on cardiac glucose metabolism in diabetic ovariectomized female rats

BACKGROUND

Diabetic cardiometabolic disorders are characterized by significant changes in cardiac metabolism and are increased in postmenopausal women, which emphasize the role of 17β-estradiol (E2). Despite this, there are few safe and effective pharmacological treatments for these disorders. The role of G protein-coupled estrogen receptor (GPR30), which mediates the non-genomic effects of E2, is mostly unexplored.

METHODS

In this study, we used ovariectomy (menopausal model) and type 2 diabetic (T2D) rats' models to evaluate the preclinical action of G-1 (GPR30 agonist) against cardiometabolic disorders. T2D was induced by a high-fat diet and a low dose of streptozotocin. G-1 was administrated for six weeks after the establishment of T2D.

RESULTS

We found that G-1 counteracts the effects of T2D and ovariectomy by increasing the body weight, reducing fasting blood sugar, heart weight, and heart weight to body weight ratio. Also, both ovariectomy and T2D led to decreases in the cardiac protein levels of hexokinase 2 (HK2) and GLUT4, while G-1-treated female rats reversed these changes and only increased HK2 protein level. In addition, T2D and ovariectomy increased glucose and glycogen content in the heart, but G-1 treatment significantly reduced them.

CONCLUSIONS

In conclusion, our work demonstrates that G-1 as a selective GPR30 agonist is a viable therapeutic approach against T2D and cardiometabolic diseases in multiple preclinical female models.

Protective effects of calorie restriction and 17-β estradiol on cardiac hypertrophy in ovariectomized obese rats

Obesity and menopause lead to cardiovascular diseases. Calorie restriction (CR) can modulate estrogen deficiency and obesity-related cardiovascular diseases. The protective effects of CR and estradiol on cardiac hypertrophy in ovariectomized obese rats were explored in this study. The adult female Wistar rats were divided into sham and ovariectomized (OVX) groups that received a high-fat diet (60% HFD) or standard diet (SD) or 30% CR for 16 weeks, and then, 1mg/kg E2 (17-β estradiol) was injected intraperitoneally every 4 days for four weeks in OVX-rats. Hemodynamic parameters were evaluated before and after each diet. Heart tissues were collected for biochemical, histological, and molecular analysis. HFD consumption led to weight gain in sham and OVX rats. In contrast, CR and E2 led to body weight loss in these animals. Also, heart weight (HW), heart weight/body weight (HW/BW) ratio, and left ventricular weight (LVW) were enhanced in OVX rats that received SD and HFD. E2 reduced these indexes in both diet conditions but reduction effects of CR were seen only in HFD groups. HFD and SD feeding increased hemodynamic parameters, ANP (atrial natriuretic peptide) mRNA expression, and TGF-β1(transforming growth factor-beta 1) protein level in the OVX animals, while CR and E2 reduced these factors. Cardiomyocyte diameter and hydroxyproline content were increased in the OVX-HFD groups. Nevertheless, CR and E2 decreased these indicators. The results showed that CR and E2 treatment reduced obesity-induced-cardiac hypertrophy in ovariectomized groups (20% and 24% respectively). CR appears to have almost as reducing effects as estrogen therapy on cardiac hypertrophy. The findings suggest that CR can be considered a therapeutic candidate for postmenopausal cardiovascular disease.

Selective estrogen receptor α and β antagonist aggravate cardiovascular dysfunction in type 2 diabetic ovariectomized female rats

OBJECTIVES

Type 2 diabetes (T2D) is a major risk factor for cardiovascular disorders (CVD), characterized by pathological diastolic as well as systolic dysfunction, ventricular dilation, and cardiomyocyte hypertrophy. CVD is the main cause of death in postmenopausal women. Estradiol (E2) has protective effects on cardiovascular function. The biological effects of E2 are mainly mediated by classical estrogen receptors (ERs). The present study aimed to investigate the cardioprotective effects of classical ERs in ovariectomized (OVX) diabetic female rats.

METHODS

T2D was induced in female rats by high-fat diet feeding along with a low dose of streptozotocin. Then diabetic animals were divided into eight groups: Sham-control, OVX, OVX + Vehicle (Veh), OVX + E2, OVX + E2 + MPP (ERα antagonist), OVX + E2 + PHTPP (ERβ antagonist), OVX + E2 + Veh, OVX + E2 + MPP + PHTPP. Animals received E2, MPP, and PHTPP every four days for 28 days. At the end blood was collected, serum separated, and used for biochemical parameters. Heart tissue was used for cardiac angiotensin II and cytokines measurement.

RESULTS

E2 treatment improved the metabolic disorders caused by T2D, and its receptor antagonists intensified the effects of T2D on the metabolic status. Also, E2 therapy decreased cardiac inflammatory cytokines, and MPP and PHTPP increased cardiac inflammation by increasing TNF-α and IL-6 and decreasing IL-10.

CONCLUSIONS

Classical ERs have protective effects on diabetic hearts by improving the metabolic status and inflammatory balance.

Adipose tissue and ovarian aging: Potential mechanism and protective strategies

Ovarian aging occurs approximately 10 years prior to the natural age-associated functional decline of other organ systems. With the increase of life expectancy worldwide, ovarian aging has gradually become a key health problem among women. Therefore, understanding the causes and molecular mechanisms of ovarian aging is very essential for the inhibition of age-related diseases and the promotion of health and longevity in women. Recently, studies have revealed an association between adipose tissue (AT) and ovarian aging. Alterations in the function and quantity of AT have profound consequences on ovarian function because AT is central for follicular development, lipid metabolism, and hormonal regulation. Moreover, the interplay between AT and the ovary is bidirectional, with ovary-derived signals directly affecting AT biology. In this review, we summarize the current knowledge of the complex molecular mechanisms controlling the crosstalk between the AT and ovarian aging, and further discuss how therapeutic targeting of the AT can delay ovarian aging.

The brain neuropeptides and STAT3 mediate the inhibitory effect of 17-β Estradiol on central leptin resistance in young but not aged female high-fat diet mice

Aging and menopause effect on body composition and energy balance. Estrogen (E2) plays an important role in body's metabolism. The aim of the present study was to determine changes in leptin function in young intact and ovariectomized (OVX) animals in comparison to the aged animals treated with E2. Young (Intact and OVX 4 months) and aged (19-21 months) female mice were fed High-fat diet (HFD) for 12 weeks and, then they were divided into eight groups including: Intact + OIL, Intact + E2, Intact + Pair body weight (PBW), OVX + OIL, OVX + E2, OVX + PBW, Aged + OIL, and Aged + E2. E2 was administered subcutaneously every four days for four weeks. Responsiveness to leptin was assessed by measuring energy balance components. Results showed that eating HFD increased weight and calorie consumption in young mice, and chronic treatment with E2 decreased both these variables in young animals. E2 only improved the sensitivity to leptin in young animals. Treatment with E2 resulted in increased α-MSH neuropeptide, reduced NPY and AgRP neuropeptides in the brain, and decreased serum leptin in the young animals. Also, treatment with E2 increased the expression of p-STAT3 molecular level in the hypothalamic arcuate nucleus (ARC) in the young animals. Our results indicated that response to E2 depended on age and E2 protects young HFD fed mice from obesity and improves leptin sensitivity.

Menstrual cycle impacts adipokine and lipoprotein responses to acute high-intensity intermittent exercise bout

Due to hormonal fluctuation, the menstrual cycle impacts inflammatory response and lipid metabolism; moreover, the anti-atherogenic and anti-inflammatory effects of exercise in this cycle, mainly high-intensity intermittent exercise (HIIE), need to be examined. Therefore, the aim of the current study was to investigate the influence of menstrual cycle phases on adipokine and lipoprotein responses after acute HIIE sessions in healthy women. Fourteen women (age: 24 ± 2 years; BMI: 22.79 ± 1.89 kg·m²) were recruited to perform two HIIE sessions (10 × 1 min running at 90% of maximum aerobic velocity, with 1 min recovery); one during the follicular phase (FP) and other during the luteal phase (LP), randomly. Blood samples were collected at rest, immediately, and 60 min after HIIE sessions. Macrophage inflammatory protein-1α (MIP-1α), leptin, adiponectin, total cholesterol, triacylglycerol (TAG), HDL-c, and glucose concentrations were analyzed. At rest, higher MIP-1α concentrations were observed during the LP compared to FP (p = 0.017). Likewise, leptin (p = 0.050), LDL-c (p = 0.015), and non-HDL (p = 0.016) were statistically higher in the LP. In contrast, the adiponectin/leptin ratio was lower in the LP compared to the ratio found in the FP (p = 0.032). Immediately post-HIIE sessions, in both menstrual phases, higher TAG (p = 0.001) and HDL-c (p = 0.001) concentrations were found, which returned to resting levels after 60 min. In conclusion, adipokine and lipoprotein responses after a single HIIE session are regulated by the phase of the menstrual cycle, contributing to inflammatory conditions, and demonstrating the importance of considering the phases of the menstrual cycle for the periodization of physical training.

Aging Reduces Estradiol Protection Against Neural but Not Metabolic Effects of Obesity in Female 3xTg-AD Mice

Vulnerability to Alzheimer's disease (AD) is increased by several risk factors, including midlife obesity, female sex, and the depletion of estrogens in women as a consequence of menopause. Conversely, estrogen-based hormone therapies have been linked with protection from age-related increases in adiposity and dementia risk, although treatment efficacy appears to be affected by the age of initiation. Potential interactions between obesity, AD, aging, and estrogen treatment are likely to have significant impact on optimizing the use of hormone therapies in postmenopausal women. In the current study, we compared how treatment with the primary estrogen, 17β-estradiol (E2), affects levels of AD-like neuropathology, behavioral impairment, and other neural and systemic effects of preexisting diet-induced obesity in female 3xTg-AD mice. Importantly, experiments were conducted at chronological ages associated with both the early and late stages of reproductive senescence. We observed that E2 treatment was generally associated with significantly improved metabolic outcomes, including reductions in body weight, adiposity, and leptin, across both age groups. Conversely, neural benefits of E2 in obese mice, including decreased β-amyloid burden, improved behavioral performance, and reduced microglial activation, were observed only in the early aging group. These results are consistent with the perspective that neural benefits of estrogen-based therapies require initiation of treatment during early rather than later phases of reproductive aging. Further, the discordance between E2 protection against systemic versus neural effects of obesity across age groups suggests that pathways other than general metabolic function, perhaps including reduced microglial activation, contribute to the mechanism(s) of the observed E2 actions. These findings reinforce the potential systemic and neural benefits of estrogen therapies against obesity, while also highlighting the critical role of aging as a mediator of estrogens' protective actions.

17β-Estradiol improves insulin signalling and insulin resistance in the aged female hearts: Role of inflammatory and anti-inflammatory cytokines

Aging effects in energy balance in all tissues and organs, including the cardiovascular. The risk of cardiovascular disease is drastically higher in postmenopausal women than in premenopausal women. Estrogen plays an important role in the cardiac function and body's metabolism. The aim of this study was to determine whether 17β-estradiol (E2) has beneficial effects on insulin resistance and some key stages of the insulin signalling pathway in the aged hearts. Young and aged female Wistar rats were ovariectomized and were randomly divided into three groups: young (YS) and aged (AS) sham, young (YV) and aged (AV) vehicle, and young (YE2) and aged (AE2) E2 treatment groups. E2 (1 mg/kg) was administrated every four days for four weeks. Results showed that ovariectomy increased fasting blood glucose, insulin, and HOMAIR in young, while none of these parameters was affected in aged animals. On the other hand, aging itself increased these variables. Furthermore, E2 therapy alleviated these changes in both young and aged animals. Moreover, aging also decreased the p-IRS1, p-Akt level, and translocation of GLUT4 to the plasma membrane. E2 reduced the negative impact of menopause and aging on insulin sensitivity by favoring increase in the level of IL-10 and decrease in the levels of TNF-α and IL-1β. Our results indicated that the heart response to E2 depended on age, and E2 increased insulin sensitivity in the heart of both young and aged animals by altering inflammatory conditions. Determining the exact mechanism of this action is suggested in future studies.