Long-term effects of ovarian follicular depletion in rats by 4-vinylcyclohexene diepoxide

Dynamics of serum exosome microRNA profile altered by chemically induced estropause and rescued by estrogen therapy in female mice

The decline in the ovarian reserve leads to menopause and reduced serum estrogens. MicroRNAs are small non-coding RNAs, which can regulate gene expression and be secreted by cells and trafficked in serum via exosomes. Serum miRNAs regulate tissue function and disease development. Therefore, the aim of this study was to identify miRNA profiles in serum exosomes of mice induced to estropause and treated with 17β-estradiol (E2). Female mice were divided into three groups including control (CTL), injected with 4-Vinylcyclohexene diepoxide (VCD), and injected with VCD plus E2 (VCD + E2). Estropause was confirmed by acyclicity and a significant reduction in the number of ovarian follicles (p < 0.05). Body mass gain during estropause was higher in VCD and VCD + E2 compared to CTL females (p = 0.02). Sequencing of miRNAs was performed from exosomes extracted from serum, and 402 miRNAs were detected. Eight miRNAs were differentially regulated between CTL and VCD groups, seven miRNAs regulated between CTL and VCD + E2 groups, and ten miRNAs regulated between VCD and VCD + E2 groups. Only miR-200a-3p and miR-200b-3p were up-regulated in both serum exosomes and ovarian tissue in both VCD groups, suggesting that these exosomal miRNAs could be associated with ovarian activity. In the hepatic tissue, only miR-370-3p (p = 0.02) was up-regulated in the VCD + E2 group, as observed in serum. Our results suggest that VCD-induced estropause and E2 replacement have an impact on the profile of serum exosomal miRNAs. The miR-200 family was increased in serum exosomes and ovarian tissue and may be a candidate biomarker of ovarian function.

Spatial learning and memory impairment at the post-follicular depletion state is associated with reduced hippocampal glucose uptake

The menopausal transition is a complex neuroendocrine aging process affecting brain structure and metabolic function. Such changes are consistent with neurological sequelae noted following the menopausal transition, including cognitive deficits. Although studies in rodent models of the menopause revealed changes in learning and memory, little is known about the structural and metabolic changes in the brain regions serving the cognitive function in these models. The administration 4-vinylcyclohexene diepoxide (VCD) in laboratory animals results in follicular depletion, and thus, is a powerful translational tool that models the human menopause. In the studies presented here, we evaluated behavior, brain structure, and metabolism in young female rats administered with either VCD or vehicle for 15 days across the early, mid, and post-follicular depletion states at 1-, 2-, and 3-months post-final injection, respectively. Additionally, we evaluated the serum hormonal profile and ovarian follicles based on the estrous cycle pattern. Positron emission tomography (PET) was utilized to determine regional brain glucose metabolism in the hippocampus, medial prefrontal cortex, and striatum. Subsequently, the rats were euthanized for ex-vivo magnetic resonance imaging (MRI) to assess regional brain volumes. VCD-induced rats at the post-follicular depleted time points had diminished spatial learning and memory as well as reduced hippocampal glucose uptake. Additionally, VCD-induced rats at post-follicular depletion time points had marked reductions in estradiol, progesterone, and anti-mullerian hormone with an increase in follicle-stimulating hormone. These rats also exhibited fewer ovarian follicles, indicating that substantial ovarian function loss during post-follicular time points impairs the female rats' spatial learning/memory abilities and triggers the metabolic changes in the hippocampus.

Dehydroepiandrosterone modulates the PTEN/PI3K/AKT signaling pathway to alleviate 4-vinylcyclohexene diepoxide-induced premature ovarian insufficiency in rats

Dehydroepiandrosterone (DHEA) is frequently integrated as an adjuvant in over a quarter of controlled ovarian hyperstimulation (COH) protocols, despite the ongoing debate regarding its impact. This study aimed to evaluate the efficacy and mechanism of action of DHEA on ovarian follicular development and ovarian response in rats with varying ovarian reserves. The study involved 75 rats categorized into 15 distinct groups. The ovarian tissues of rats in both the normal ovarian reserve group and the premature ovarian insufficiency (POI) group, induced by 4-vinylcyclohexene diepoxide (VCD) injection, were subjected to histomorphological and biochemical analyses following the administration of DHEA, either alone or in combination with COH. Follicle counting was performed on histological sections obtained from various tissues. Serum concentrations of anti-Müllerian hormone (AMH) and the quantification of specific proteins in ovarian tissue, including phosphatase and tensin homolog of chromosome 10 (PTEN), phosphoinositide 3-kinase (PI3K), phosphorylated protein kinase B (pAKT), cyclooxygenase 2 (COX-2), caspase-3, as well as assessments of total antioxidant status and total oxidant status, were conducted employing the ELISA method. The impact of DHEA exhibited variability based on ovarian reserve. In the POI model, DHEA augmented follicular development and ovarian response to the COH protocol by upregulating the PTEN/PI3K/AKT signaling pathway, mitigating apoptosis, inflammation, and oxidative stress, contrary to its effects in the normal ovarian reserve group. In conclusion, it has been determined that DHEA may exert beneficial effects on ovarian stimulation response by enhancing the initiation of primordial follicles and supporting antral follicle populations.

Effects of an Anti-Fertility Product on Reproductive Structures of Common Vole Males and Residues of Compounds

Some rodent species cause significant damage to agriculture and forestry, and some can transmit pathogens to humans and livestock. The common vole (Microtus arvalis) is widespread in Europe, and its population outbreaks have resulted in massive crop loss. Bait-based fertility control could contribute to rodent pest management. Bait containing 4-vinylcyclohexene diepoxide (VCD) and triptolide (TP), registered as ContraPest®, was delivered to male common voles for 14 or 28 consecutive days. The effects on reproductive structures and residues in the liver and testes were assessed. There was no effect on testis weight, sperm viability, sperm motility and oxidative stress in sperm cells. Results regarding the mitochondrial membrane potential of sperm, DNA fragmentation and progressively motile sperm cells were inconclusive. However, there was an increase in morphological sperm defects in voles treated for 14/28 days and fewer normal sperm cells in voles treated for 28 days. There were no TP residues in the testes, few and low TP residues and no VCD residues in liver tissues, making considerable secondary exposure to non-target species unlikely. Treatments with VCD + TP seemed to have minor effects on the reproductive organs of males. Further studies should evaluate the effect of VCD + TP on females and on the reproductive success of common voles and other pest rodent species.

The Protective Role of Magnoliae Flos in Preventing Ovotoxicity and Managing Ovarian Function: An In Vitro and In Vivo Study

Magnoliae Flos (MF) is a medicinal herb widely employed in traditional medicine for relieving sinusitis, allergic rhinitis, headaches, and toothaches. Here, we investigated the potential preventive effects of MF extract (MFE) against 4-vinylcyclohexene diepoxide (VCD)-induced ovotoxicity in ovarian cells and a mouse model of premature ovarian insufficiency (POI). The cytoprotective effects of MFE were assessed using CHO-K1 or COV434 cells. In vivo, B6C3F1 female mice were intraperitoneally injected with VCD for two weeks to induce POI, while MFE was orally administered for four weeks, beginning one week before VCD administration. VCD led to a significant decline in the viabilities of CHO-K1 and COV434 cells and triggered excessive reactive oxygen species (ROS) production and apoptosis specifically in CHO-K1 cells. However, pretreatment with MFE effectively prevented VCD-induced cell death and ROS generation, while also activating the Akt signaling pathway. In vivo, MFE increased relative ovary weights, follicle numbers, and serum estradiol and anti-Müllerian hormone levels versus controls under conditions of ovary failure. Collectively, our results demonstrate that MFE has a preventive effect on VCD-induced ovotoxicity through Akt activation. These results suggest that MFE may have the potential to prevent and manage conditions such as POI and diminished ovarian reserve.

THE EFFECT OF 4-VINYLCYCLOHEXENE DIEPOXIDE ON FEMALE NUTRIA (MYOCASTOR COYPUS) FERTILITY IN CAPTIVITY-A PILOT STUDY

The nutria (Myocastor coypus) is a globally widespread invasive species. Attempts to eradicate nutria by shooting, poisoning, and trapping have been mostly unsuccessful, leading to calls for the development of new control methods. The compound 4-vinylcyclohexene diepoxide (VCD) is known to cause follicular atresia in mammals and may control conception when administered orally. It was hypothesized that VCD administered PO will cause follicular destruction in female nutria. VCD (250 mg/kg PO) was administered or coconut oil, as a control, to five nutria females each for 12 d. Sixty days following VCD exposure, males were introduced to the females. Over the following 7 mon, the effect of VCD on nutria fertility was assessed by conducting ultrasound monitoring to determine pregnancy status and measuring blood serum progesterone and estradiol levels. Finally, after performing ovariectomies, viable follicles were counted on histologic ovarian cortical sections. It was found that the female estrous cycles became synchronized, suggesting a Whitten effect in this species. Also, an increase in the females' serum progesterone levels following the introduction of males occurred, suggesting a male presence effect. Orally administered doses of 250 mg/kg VCD for 12 d had no significant effect on nutria pregnancy rates or on the number of follicles in the ovaries examined. Further studies, using a higher dose or longer administration period, are necessary to conclude whether orally administered VCD can be used as a contraceptive agent for nutria.

Transcriptome analysis during 4-vinylcyclohexene diepoxide exposure-induced premature ovarian insufficiency in mice

The occupational chemical 4-Vinylcyclohexene diepoxide (VCD) is a reproductively toxic environmental pollutant that causes follicular failure, leading to premature ovarian insufficiency (POI), which significantly impacts a woman's physical health and fertility. Investigating VCD's pathogenic mechanisms can offer insights for the prevention of ovarian impairment and the treatment of POI. This study established a mouse model of POI through intraperitoneal injection of VCD into female C57BL/6 mice for 15 days. The results were then compared with those of the control group, including a comparison of phenotypic characteristics and transcriptome differences, at two time points: day 15 and day 30. Through a comprehensive analysis of differentially expressed genes (DEGs), key genes were identified and validated some using RT-PCR. The results revealed significant impacts on sex hormone levels, follicle number, and the estrous cycle in VCD-induced POI mice on both day 15 and day 30. The DEGs and enrichment results obtained on day 15 were not as significant as those obtained on day 30. The results of this study provide a preliminary indication that steroid hormone synthesis, DNA damage repair, and impaired oocyte mitosis are pivotal in VCD-mediated ovarian dysfunction. This dysfunction may have been caused by VCD damage to the primordial follicular pool, impairing follicular development and aggravating ovarian damage over time, making it gradually difficult for the ovaries to perform their normal functions.

Effect of calorie restriction on redox status during chemically induced estropause in female mice

In females, there is a continuous decline of the ovarian reserve with age, which results in menopause in women or estropause in mice. Loss of ovarian function results in metabolic alterations in mice and women. Based on this, we aimed to evaluate the effect of caloric restriction (CR) on redox status and metabolic changes in chemically induced estropause in mice. For this, mice were divided into four groups (n = 10): cyclic ad libitum (AL), cyclic 30% CR, AL estropause, and estropause 30% CR. Estropause was induced using 4-vinylcyclohexene diepoxide (VCD) for 20 consecutive days in 2-month-old females. The CR protocol started at 5 months of age and the treatments lasted for 4 months. The CR females gained less body weight than AL females (p < 0.001) and had lower glycemic curves in response to glucose tolerance test (GTT). The AL estropause females had the highest body weight and body fat, despite having lower food intake. However, the estropause females on 30% CR lost the most body weight and had the lowest amount of body fat compared to all groups. The effect of 30% CR on redox status in fat and liver tissue was similar for cyclic and estropause females. Interestingly, estropause decreased ROS in adipose tissue, while increasing it in the liver. No significant effects of CR on redox status were observed. Chemically induced estropause did not influence the response to 30% CR on glucose tolerance and redox status; however, weight loss was exarcebated compared to cyclic females.

Analysis of the cognitive and functional behavior of female rats in the periestropause after hormone therapy with estrogen

Perimenopause is a critical period, with severe cycle irregularity and lower estrogen secretion altering redox state biomarkers, leading to behavioral changes. The estrogen hormonal therapy (EHT) being commonly used to alleviate climacteric effects. Therefore, the aim of this study was to analyze anxiolytic profile, recognition memory (short and long term), ambulation, redox status, cell synaptic activity in locus coeruleus and hippocampus of Wistar rats in the periestropause after EHT. Forty rats participated in the study; 20 were treated with corn oil (group 21Mo/Veh; corn oil/0.2 mL/sc; 2x/week) and 20 were submitted to EHT (group 21Mo/E2; 17β-estradiol/15 μg/Kg/sc; 2x/week) for 120 days. Open field, elevated plus maze, object recognition (RO), and footprint tests were performed immediately before and at the end of the treatment period. From the decapitated brains, isolated hippocampus were destined for biochemical analysis, in turn, perfused brains were destined for histological analysis. The 21Mo/E2 group had a significantly greater total time in the central region and a significantly greater number of entries into the open arms compared to the 21Mo/Veh group, as in crossing, rearing and grooming behaviors, evidencing an anxiolytic profile. In the RO test, the 21Mo/Veh group decreased long-term memory, and the 21Mo/E2 group maintained the same index as at 17 months of age, in addition to a better balance of the hippocampal redox state, prevention of neuronal cell loss and better gait. Based on the results, it appears that exogenous E2 supplementation during periestropause may help preserve neurological functions and potentially prevent neuropsychological and neurodegenerative disorders.

Impact of ovary-intact menopause in a mouse model of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) afflicts over half of all patients with heart failure and is a debilitating and fatal syndrome affecting postmenopausal women more than any other demographic. This bias toward older females calls into question the significance of menopause in the development of HFpEF, but this question has not been probed in detail. In this study, we report the first investigation into the impact of ovary-intact menopause in the context of HFpEF. To replicate the human condition as faithfully as possible, vinylcyclohexene dioxide (VCD) was used to accelerate ovarian failure (AOF) in female mice while leaving the ovaries intact. HFpEF was established with a mouse model that involves two stressors typical in humans: a high-fat diet and hypertension induced from the nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME). In young female mice, AOF or HFpEF-associated stressors independently induced abnormal myocardial strain indicative of early subclinical systolic and diastolic cardiac dysfunction. HFpEF but not AOF was associated with elevations in systolic blood pressure. Increased myocyte size and reduced myocardial microvascular density were not observed in any group. Also, a broad panel of measurements that included echocardiography, invasive pressure measurements, histology, and serum hormones revealed no interaction between AOF and HFpEF. Interestingly, AOF did evoke a higher density of infiltrating cardiac immune cells in both healthy and HFpEF mice, suggestive of proinflammatory effects. In contrast to young mice, middle-aged "old" mice did not exhibit cardiac dysfunction from estrogen deprivation alone or from HFpEF-related stressors.NEW & NOTEWORTHY This is the first preclinical study to examine the impact of ovary-intact menopause [accelerated ovarian failure (AOF)] on HFpEF. Echocardiography of young female mice revealed early evidence of diastolic and systolic cardiac dysfunction apparent only on strain imaging in HFpEF only, AOF only, or the combination. Surprisingly, AOF did not exacerbate the HFpEF phenotype. Results in middle-aged "old" females also showed no interaction between HFpEF and AOF and, importantly, no cardiovascular impact from HFpEF or AOF.

The impact of 17β-estradiol on the estrogen-deficient female brain: from mechanisms to therapy with hot flushes as target symptoms

Sex steroids are essential for whole body development and functions. Among these steroids, 17β-estradiol (E2) has been known as the principal "female" hormone. However, E2's actions are not restricted to reproduction, as it plays a myriad of important roles throughout the body including the brain. In fact, this hormone also has profound effects on the female brain throughout the life span. The brain receives this gonadal hormone from the circulation, and local formation of E2 from testosterone via aromatase has been shown. Therefore, the brain appears to be not only a target but also a producer of this steroid. The beneficial broad actions of the hormone in the brain are the end result of well-orchestrated delayed genomic and rapid non-genomic responses. A drastic and steady decline in circulating E2 in a female occurs naturally over an extended period of time starting with the perimenopausal transition, as ovarian functions are gradually declining until the complete cessation of the menstrual cycle. The waning of endogenous E2 in the blood leads to an estrogen-deficient brain. This adversely impacts neural and behavioral functions and may lead to a constellation of maladies such as vasomotor symptoms with varying severity among women and, also, over time within an individual. Vasomotor symptoms triggered apparently by estrogen deficiency are related to abnormal changes in the hypothalamus particularly involving its preoptic and anterior areas. However, conventional hormone therapies to "re-estrogenize" the brain carry risks due to multiple confounding factors including unwanted hormonal exposure of the periphery. In this review, we focus on hot flushes as the archetypic manifestation of estrogen deprivation in the brain. Beyond our current mechanistic understanding of the symptoms, we highlight the arduous process and various obstacles of developing effective and safe therapies for hot flushes using E2. We discuss our preclinical efforts to constrain E2's beneficial actions to the brain by the DHED prodrug our laboratory developed to treat maladies associated with the hypoestrogenic brain.

Exercise ameliorates anxious behavior and promotes neuroprotection through osteocalcin in VCD-induced menopausal mice

AIMS

As the ovaries age and women transition to menopause and postmenopause, reduced estradiol levels are associated with anxiety and depression. Exercise contributes to alleviate anxiety and depression and the bone-derived hormone osteocalcin has been reported to be necessary to prevent anxiety-like behaviors. The aim of this study was to investigate the effects of exercise on anxiety behaviors in climacteric mice and whether it was related to osteocalcin.

METHODS

Menopausal mouse model was induced by intraperitoneal injection of 4-vinylcyclohexene diepoxide (VCD). Open field, elevated plus maze, and light-dark tests were used to detect anxious behavior in mice. The content of serum osteocalcin was measured and its correlation with anxiety behavior was analyzed. BRDU and NEUN co-localization cells were detected with immunofluorescence. Western blot was applied to obtain apoptosis-related proteins.

RESULTS

The VCD mice showed obvious anxiety-like behaviors and 10 weeks of treadmill exercise significantly ameliorated the anxiety and increased circulating osteocalcin in VCD mice. Exercise increased the number of BRDU and NEUN co-localization cells in hippocampal dentate gyrus, reduced the number of impaired hippocampal neurons, inhibited the expression of BAX, cleaved Caspase3, and cleaved PARP, promoted the expression of BCL-2. Importantly, circulating osteocalcin levels were positively associated with the improvements of anxiety, the number of BRDU and NEUN co-localization cells in hippocampal dentate gyrus and negatively related to impaired hippocampal neurons.

CONCLUSION

Exercise ameliorates anxiety behavior, promotes hippocampal dentate gyrus neurogenesis, and inhibits hippocampal cell apoptosis in VCD-induced menopausal mice. They are related to circulating osteocalcin, which are increased by exercise.

Altered m6A modification is involved YAP-mediated apoptosis response in 4-vinylcyclohexene diepoxide induced ovotoxicity

4-Vinylcyclohexene diepoxide (VCD), an industrial occupational health hazard chemical associated with premature ovarian insufficiency (POI) and reproductive failure. Recently, investigators have paid an increasing attention on VCD model of menopause recapitulates the natural, physiological transition through perimenopause to menopause. The current study sought to examining the mechanisms of follicular loss and exploring the effect of the model on systems outside of the ovaries. In this study, 28 days female SD rats were injected with VCD (160 mg/kg) vehicle for 15 consecutive days, euthanized in the diestrus phase approximately 100 days after the onset of treatment. Reproductive system injury, Neuroendocrine, sex hormone levels and receptor were observed, the levels of N6-methyladenosine (m6A) RNA modification and the expression of modulator genes were first measured. The VCD treated rats showing irregular estrous cycles, significantly reduced in the number of primordial follicles, the preantral and antral follicles also decreased significantly, accompanied by the plasma level of FSH increased and anti-Mullerian hormone (AMH) were decreased. The total m6A level was significantly decreased after exposure to VCD. Moreover, ALKBH5-mediated YAP m6A modification changed in VCD - induced premature ovarian insufficiency. These present work provides a new perspective on m6A modification in the VCD-induced POI rat model, which could provide valuable insights into the mechanisms underlying follicle development and finding new therapeutic targets for follicle prematurely exhausted. Also provide novel methodological guidance and endocrine basis to guide research and extend the applications in premature ovarian insufficiency model.

Fertility Control for Wildlife: A European Perspective

Trends of human population growth and landscape development in Europe show that wildlife impacts are escalating. Lethal methods, traditionally employed to mitigate these impacts, are often ineffective, environmentally hazardous and face increasing public opposition. Fertility control is advocated as a humane tool to mitigate these impacts. This review describes mammalian and avian wildlife contraceptives' effect on reproduction of individuals and populations, delivery methods, potential costs and feasibility of using fertility control in European contexts. These contexts include small, isolated wildlife populations and situations in which lethal control is either illegal or socially unacceptable, such as urban settings, national parks and areas where rewilding occurs. The review highlights knowledge gaps, such as impact of fertility control on recruitment, social and spatial behaviour and on target and non-target species, provides a decision framework to assist decisions about the potential use of wildlife fertility control, and suggests eight reasons for Europe to invest in this area. Although developing and registering contraceptives in Europe will have substantial costs, these are relatively small when compared to wildlife's economic and environmental impact. Developing safe and effective contraceptives will be essential if European countries want to meet public demand for methods to promote human-wildlife coexistence.

Altered brain rhythms and behaviour in the accelerated ovarian failure mouse model of human menopause

To date, potential mechanisms of menopause-related memory and cognitive deficits have not been elucidated. Therefore, we studied brain oscillations, their phase–amplitude coupling, sleep and vigilance state patterns, running wheel use and other behavioural measures in a translationally valid mouse model of menopause, the 4-vinylcyclohexene-diepoxide-induced accelerated ovarian failure. After accelerated ovarian failure, female mice show significant alterations in brain rhythms, including changes in the frequencies of θ (5–12 Hz) and γ (30–120 Hz) oscillations, a reversed phase–amplitude coupling, altered coupling of hippocampal sharp-wave ripples to medial prefrontal cortical sleep spindles and reduced δ oscillation (0.5–4 Hz) synchrony between the two regions during non-rapid eye movement sleep. In addition, we report on significant circadian variations in the frequencies of θ and γ oscillations, and massive synchronous δ oscillations during wheel running. Our results reveal novel and specific network alterations and feasible signs for diminished brain connectivity in the accelerated ovarian failure mouse model of menopause. Taken together, our results may have identified changes possibly responsible for some of the memory and cognitive deficits previously described in this model. Corresponding future studies in menopausal women could shed light on fundamental mechanisms underlying the neurological and psychiatric comorbidities present during this important transitional phase in women’s lives.

Shudi Erzi San relieves ovary aging in laying hens

Poultry meat and eggs are a primary source of animal protein. To meet the market needs, high yield laying hens are reared continuously, resulting in quick ovary aging. Thus, we investigated the anti-aging effects of Shudi Erzi San (SES) on laying hens. Sixty 300-day-old laying hens were divided into 2 experimental groups and a control group. The control group was fed on a basic diet, which was supplemented with 1% and 2% SES for experimental groups I and II, respectively. Egg quality and changes in serum hormones and blood-biochemical indicators of laying hens were determined. The rate of egg production was significantly higher in group Ⅱ than in both the control and group Ⅰ by 9.29 and 8.22 percentage points, respectively (P < 0.05). Eggshell strength of groups Ⅰ and Ⅱ were significantly higher than that of the control group (P < 0.01). Albumen height and Haugh Units of group Ⅱ were significantly higher than those of the control (P < 0.05). Serum levels of follicle stimulating hormone and estradiol in group Ⅱ were significantly higher than those of both the control and group Ⅰ (P < 0.05), whereas groups Ⅰ and Ⅱ had significantly higher serum levels of luteinizing hormone than the control (P < 0.05). Levels of superoxide dismutase (SOD) did not significantly differ between the control and group Ⅰ (P > 0.05), but SOD and malondialdehyde (MDA) levels in group Ⅱ were significantly higher and lower, respectively (P < 0.05) when compared to the control. Compared with the control, uric acid levels in groups Ⅰ and Ⅱ were significantly lower (P < 0.05), as was urea nitrogen in group Ⅱ (P < 0.05). Transcriptome and KEGG pathway analysis of ovarian tissues of laying hens showed a significant immune related signal pathway as the possible main regulator of a lysosome related signal pathway. Thus, supplementing chicken feed with SES improves egg production and quality and alleviates ovarian decline in laying hens.

Aging-related changes in metabolic indicators in female rats and their management with Tinospora cordifolia

Conflicting reports of HRT necessitates exploration of therapeutic interventions with the least side effects to preserve metabolic homeodynamics in women later in life. The current study was designed to elucidate the cumulative effects of aging and/or high fat diet (HFD) on some metabolic indicators and their management by Tinospora cordifolia stem powder (TCP) using middle-aged acyclic and young adult cyclic female rats as the model system. Animals were fed on either normal chow or HFD supplemented with or without TCP. Blood and liver tissue were collected for biochemical, and histological studies as well as for expression of proteins regulating lipid metabolism. Animals fed with TCP supplemented normal chow feed showed bodyweight management over 12-weeks despite their high feed and calories intake compared to young and age-matched controls as well as HFD-fed animals. TCP dose used was not toxic and rather prevented age-associated liver dysfunctions and ameliorated dyslipidemia and oxidative stress, normalized blood glucose, insulin, leptin, and secretary pro-inflammatory cytokines. Further, bodyweight management effect of TCP was observed to target AMPK signalling pathway as the mediator of lipogenesis, sterol biosynthesis, lipolysis, and β-oxidation of fatty acids. These findings suggest that TCP supplementation in diet may be a potential interventional strategy to ameliorate aging-associated hepatic and metabolic dysfunctions and to promote healthy aging.

Effects of 4-vinylcyclohexene diepoxide on the cell cycle, apoptosis, and steroid hormone secretion of goat ovarian granulosa cells

4-Vinylcyclohexene diepoxide (VCD) is a potentially hazardous industrial chemical that may enter a goat's body in various ways during industrial breeding. Ovarian granulosa cells (GCs) play a critical role in supporting follicle development and hormone synthesis. However, there are few studies on the effect of VCD on goat ovarian GCs. In this study, goat ovarian GCs were isolated and treated with VCD. The results showed that treatment with VCD increased the proportion of S phase and G2/M cells, but decreased the proportion of G1 phase. VCD treatment significantly inhibited the expression of cyclin A and cyclin-dependent kinase 2 (CDK2). But the expression levels of p21 and p27 were increased. VCD could induce an apparent increase in the proportion of apoptosis and the level of cleaved caspase 3. Treatment with VCD significantly reduced the progesterone and estrogen concentration in the medium in which goat ovarian GCs were cultured. Correspondingly, the expression level of steroidogenic acute regulatory protein (STAR) was significantly downregulated. Treatment with 0.25 and 0.5 mM VCD, the protein expression level of insulin-like growth factor 1 receptor (IGF1R) and Akt were significantly decreased. Moreover, treatment with 0.25 mM VCD significantly inhibited the phosphorylation of Akt. In conclusion, VCD exposure had cytotoxic effects such as decreased cell viability, disordered cell cycle, increased apoptosis, and interference with steroid hormone synthesis on goat GCs. These cytotoxic effects of VCD on goat GCs may be due to the downregulation of IGF1R and the inhibition of IGF1R/Akt signaling pathway.

The status of fertility control for rodents-recent achievements and future directions

Management of overabundant rodents at a landscape scale is complex but often required to sustainably reduce rodent abundance below damage thresholds. Current conventional techniques such as poisoning are not species specific, with some approaches becoming increasingly unacceptable to the general public. Fertility control, first proposed for vertebrate pest management over 5 decades ago, has gained public acceptance because it is perceived as a potentially more species-specific and humane approach compared with many lethal methods. An ideal fertility control agent needs to induce infertility across one or more breeding seasons, be easily delivered to an appropriate proportion of the population, be species specific with minimal side-effects (behavioral or social structure changes), and be environmentally benign and cost effective. To date, effective fertility control of rodents has not been demonstrated at landscape scales and very few products have achieved registration. Reproductive targets for fertility control include disrupting the hormonal feedback associated with the hypothalamic-pituitary-gonadal axis, gonad function, fertilization, and/or early implantation. We review progress on the oral delivery of various agents for which laboratory studies have demonstrated efficacy in females and/or males and synthesize progress with the development and/or use of synthetic steroids, plant extracts, ovarian specific peptides, and immunocontraceptive vaccines. There are promising results for field application of synthetic steroids (levonorgestrel, quinestrol), chemosterilants (4-vinylcyclohexene diepoxide), and some plant extracts (triptolide). For most fertility control agents, more research is essential to enable their efficient and cost-effective delivery such that rodent impacts at a population level are mitigated and food security is improved.

Clinically Used Hormone Formulations Differentially Impact Memory, Anxiety-Like, and Depressive-Like Behaviors in a Rat Model of Transitional Menopause

A variety of U.S. Food and Drug Administration-approved hormone therapy options are currently used to successfully alleviate unwanted symptoms associated with the changing endogenous hormonal milieu that occurs in midlife with menopause. Depending on the primary indication for treatment, different hormone therapy formulations are utilized, including estrogen-only, progestogen-only, or combined estrogen plus progestogen options. There is little known about how these formulations, or their unique pharmacodynamics, impact neurobiological processes. Seemingly disparate pre-clinical and clinical findings regarding the cognitive effects of hormone therapies, such as the negative effects associated with conjugated equine estrogens and medroxyprogesterone acetate vs. naturally circulating 17β-estradiol (E2) and progesterone, signal a critical need to further investigate the neuro-cognitive impact of hormone therapy formulations. Here, utilizing a rat model of transitional menopause, we administered either E2, progesterone, levonorgestrel, or combinations of E2 with progesterone or with levonorgestrel daily to follicle-depleted, middle-aged rats. A battery of assessments, including spatial memory, anxiety-like behaviors, and depressive-like behaviors, as well as endocrine status and ovarian follicle complement, were evaluated. Results indicate divergent outcomes for memory, anxiety, and depression, as well as unique physiological profiles, that were dependent upon the hormone regimen administered. Overall, the combination hormone treatments had the most consistently favorable profile for the domains evaluated in rats that had undergone experimentally induced transitional menopause and remained ovary-intact. The collective results underscore the importance of investigating variations in hormone therapy formulation as well as the menopause background upon which these formulations are delivered.

Menopause, hormone therapy and cognition: maximizing translation from preclinical research

Menopause-associated and hormone-associated cognitive research has a rich history built from varied disciplines and species. This review discusses landmark rodent and human work addressing cognitive outcomes associated with varied experiences of menopause and hormone therapy. Critical variables in menopause and cognitive aging research are considered, including menopause etiology, background hormone milieu and parameters of exposure to estrogens and progestogens. Recent preclinical research has identified that menopause and ovarian hormone fluctuations across many neurobiological systems affect cognitive aging, mapping novel avenues for future research. Preclinical models provide insight into complex interdisciplinary relationships in a systematic and highly controlled fashion. We highlight that acknowledging the strengths and weaknesses for both preclinical and clinical research approaches is vital to accurate interpretation, optimal translation and the direction of future research. There is great value in collaboration and communication across preclinical and clinical realms, especially regarding reciprocal feedback of findings to advance preclinical models, improve experimental designs and enrich basic science translation to the clinic. In searching for biological mechanisms underlying the cognitive consequences of menopause and hormone therapies, it is noteworthy that clinical and preclinical scientists are grounded in the same fundamental goal of optimizing health outcomes for women across the lifespan.

Hormonal and neural responses to restraint stress in an animal model of perimenopause in female rats

The present study investigated the hormonal and neural responses to stress in a perimenopause animal model induced by 4-vinylcyclohexene diepoxide (VCD), which induces progressive follicular depletion in rodents, allowing studies on the transition to ovarian failure. Female rats, aged 28 days old, were s.c. injected for 15 consecutive days with corn oil or VCD. At 85 ± 5 days after the onset of treatment, the jugular vein was cannulated in the afternoon of metoestrus and in next morning (dioestrus) at 10.00 am, rats were subjected to 30 minutes of restraint stress. Blood samples were withdrawn before (-5 minutes), during (2, 5, 15 and 30 minutes) and after (45, 60 and 90 minutes) stress and plasma prolactin, progesterone and corticosterone levels were measured. Animals were perfused, brains processed for c-Fos/tyrosine hydroxylase (TH) in the locus coeruleus (LC) and c-Fos/corticotrophin-releasing factor (CRF) in the paraventricular nucleus (PVN). In unstressed rats the density of β-endorphin fibres was assessed in LC and PVN. In VCD-treated rats, stress-induced prolactin peak was higher, basal and peak progesterone levels were lower, and both levels of corticosterone were similar to controls. However, the recovery period was longer for both adrenal hormones. In VCD-treated rats the number of c-Fos/TH and c-Fos/CRF-immunoreactive neurones was higher whereas the density of β-endorphin fibres was lower in LC and PVN. We surmise that the hyperactivity of the LC and PVN neurones in VCD-treated rats may be a result of the lower progesterone levels that resulted in the decrease of β-endorphin content in both nuclei, thus impairing the negative-feedback mechanism in the recovery period.

Development of a Chemical Reproductive Aging Model in Female Rats

Women are born with an abundant but finite pool of ovarian follicles, which naturally and progressively decreased during their reproductive years until menstrual periods stop permanently (menopause). Perimenopause represents the transition from reproductive to non-reproductive life. It is usually characterized by neuroendocrine, metabolic and behavioral changes, which result from a follicular depletion and reduced number of ovarian follicles. During this period, around 45-50 years old, women are more likely to express mood disorders, anxiety, irritability and vasomotor symptoms. The current animal models of reproductive aging do not successfully replicate human perimenopause and the gradual changes that occur in this phase. While the traditional rat model of menopause involves ovariectomy or surgical menopause consisting of the rapid and definitive removal of the ovaries resulting in a complete loss of all ovarian hormones, natural or transitional menopause is achieved by the selective loss of ovarian follicles (perimenopause period). However, the natural aging rodent (around 18-24 months) model fails to reach very low estrogen concentrations and overlaps the processes of somatic and reproductive aging. The chronic exposure of young rodents to 4-vinylcyclohexene diepoxide (VCD) is a well-established experimental model for perimenopause and menopause studies. VCD induces loss of ovarian small follicles (primary and primordial) in mice and rats by accelerating the natural process of atresia (apoptosis). The VCD, ovary-intact or accelerated ovarian failure (AOF) model is the experimental model that most closely matches natural human progression to menopause mimicking both hormonal and behavioral changes typically manifested by women in perimenopause. Graphical abstract: The female reproductive system is regulated by a series of neuroendocrine events controlled by central and peripheral components. (A). The mechanisms involved in this control are extremely complex and have not yet been fully clarified. In female mammals whose ovulation (the most important event in a reproductive cycle) occurs spontaneously, reproductive success is achieved through the precise functional and temporal integration of the hypothalamus-pituitary-ovary (HPO) axis. (B). In women, loss of fertility appears to be primarily associated with exhaustion of ovarian follicles, and this process occurs progressively until complete follicular exhaustion marked by the final menstrual period (FMP). (C). While in female rodents, reproductive aging seems to begin as a neuroendocrine process, in which changes in hypothalamic/pituitary function appear independently of follicular atresia. The traditional rat model of menopause, ovariectomy or surgical menopause consists of the rapid and definitive removal of the ovaries resulting in a complete loss of all ovarian hormones. (D). The chronic exposure (15-30 days) to the chemical compound 4-vinylcyclehexene diepoxide (VCD) in young rodents accelerates gradual failure of ovarian function by progressive depletion of primordial and primary follicles, but retains residual ovarian tissue before brain alterations that occurs in women in perimenopause. Low doses of VCD cause the selective destruction of the small preantral follicles of the ovary without affecting other peripheral tissues.

Ovariectomy Influences Cognition and Markers of Alzheimer's Disease

Alzheimer's disease (AD) is one of the most devastating and costly diseases, and prevalence of AD increases with age. Furthermore, females are twice as likely to suffer from AD compared to males. The cessation of reproductive steroid hormone production during menopause is hypothesized to cause this difference. Two rodent AD models, APP21 and APP+PS1, and wild type (WT) rats underwent an ovariectomy or sham surgery. Changes in learning and memory, brain histology, amyloid-β (Aβ) deposition, levels of mRNAs involved in Aβ production and clearance, and synaptic and cognitive function were determined. Barnes maze results showed that regardless of ovariectomy status, APP+PS1 rats learned slower and had poor memory retention. Ovariectomy caused learning impairment only in the APP21 rats. High levels of Aβ42 and very low levels of Aβ40 were observed in the brain cortices of APP+PS1 rats indicating limited endogenous PS1. The APP+PS1 rats had 43-fold greater formic acid soluble Aβ42 than Aβ40 at 17 months. Furthermore, levels of formic acid soluble Aβ42 increased 57-fold in ovariectomized APP+PS1 rats between 12 and 17 months of age. The mRNA encoding Grin1 significantly decreased due to ovariectomy whereas levels of Bace1, Chat, and Prkcb all decreased with age. The expression levels of mRNAs involved in Aβ degradation and AβPP cleavage (Neprilysin, Ide, Adam9, and Psenen) were found to be highly correlated with each other as well as hippocampal Aβ deposition. Taken together, these results indicate that both ovariectomy and genotype influence AD markers in a complex manner.

Characterizing the effects of tonic 17β-estradiol administration on spatial learning and memory in the follicle-deplete middle-aged female rat

17β-estradiol (E2)-containing hormone therapy is a safe, effective way to alleviate unwanted menopause symptoms. Preclinical research has focused upon the role of E2 in learning and memory using a surgically menopausal rodent model whereby the ovaries are removed. Given that most women retain their reproductive tract and undergo a natural menopause transition, it is necessary to understand how exogenous E2 impacts a structurally intact, but follicle-deplete, system. In the current study, 8 month old female rats were administered the ovatoxin 4-vinylcyclohexene diepoxide (VCD), which accelerates ovarian follicular depletion, to model the human menopause transition. After follicular depletion, at 11 months old, rats were administered Vehicle or tonic E2 treatment for 12 days prior to behavioral evaluation on spatial working and reference memory tasks. Results demonstrated that E2 had both enhancing and impairing effects on taxed working memory depending upon the learning or retention phases of the water radial-arm maze, with no impact on reference memory. Relationships between memory scores and circulating estrogen levels were specific to follicle-depleted rats without E2 treatment. Collectively, findings demonstrate the complexity of E2 administration in a follicle-depleted background, with cognitive effects specific to working memory; furthermore, E2 administration altered circulating hormonal milieu and relationships between hormone profiles and memory. In sum, menopausal etiology impacts the parameters of E2 effects on cognition, complementing prior work with other estrogen compounds. Deciphering estrogenic actions in a system wherein the reproductive tract remains intact with follicle-depleted ovaries, thus modeling the majority or menopausal women, is critical for translational perspectives.

Endocrine profile of the VCD-induced perimenopausal model rat

During the transition to menopause, women experience a variety of physical and psychological symptoms that are directly or indirectly linked to changes in hormone secretion. Establishing animal models with intact ovaries is essential for understanding these interactions and finding new therapeutic targets. In this study, we assessed the endocrine profile, as well as the estrous cycle, in the 4-vinylcyclohexene diepoxide (VCD)-induced follicular depletion rat model in 10-day intervals over 1 month to accurately establish the best period for studies of the transition period. Twenty-eight-day-old female rats were injected daily with VCD or oil s.c. for 15 days and euthanized in the diestrus phase approximately 70, 80, 90 and 100 days after the onset of treatment. The percentage of rats showing irregular cycles and the plasma level of FSH increased only in the 100-day VCD group. Plasma anti-Müllerian hormone (AMH) and progesterone were lower in all VCD groups compared to control groups, while estradiol remained unchanged or higher. As in control groups, dihydrotestosterone (DHT) progressively decreased in the 70-90-day VCD groups; however, it was followed by a sharp increase only in the 100-day VCD group. No changes were found in plasma corticosterone, prolactin, thyroid hormones or luteinizing hormone. Based on the estrous cycle and endocrine profile, we conclude that 1) the time window from 70 to 100 days is suitable to study a perimenopause-like state in this model, and 2) regular cycles with low progesterone and AMH and normal FSH can be used as markers of the early/mid-transition period, whereas irregular cycles associated with higher FSH and DHT can be used as markers of the late transition period to estropause.

Accelerated Ovarian Failure as a Unique Model to Study Peri-Menopause Influence on Alzheimer's Disease

Despite decades of extensive research efforts, efficacious therapies for Alzheimer's disease (AD) are lacking. The multi-factorial nature of AD neuropathology and symptomatology has taught us that a single therapeutic approach will most likely not fit all. Women constitute ~70% of the affected AD population, and pathology and rate of symptoms progression are 2-3 times higher in women than men. Epidemiological data suggest that menopausal estrogen loss may be causative of the more severe symptoms observed in AD women, however, results from clinical trials employing estrogen replacement therapy are inconsistent. AD pathological hallmarks-amyloid β (Aβ), neurofibrillary tangles (NFTs), and chronic gliosis-are laid down during a 20-year prodromal period before clinical symptoms appear, which coincides with the menopause transition (peri-menopause) in women (~45-54-years-old). Peri-menopause is marked by widely fluctuating estrogen levels resulting in periods of irregular hormone-receptor interactions. Recent studies showed that peri-menopausal women have increased indicators of AD phenotype (brain Aβ deposition and hypometabolism), and peri-menopausal women who used hormone replacement therapy (HRT) had a reduced AD risk. This suggests that neuroendocrine changes during peri-menopause may be a trigger that increases risk of AD in women. Studies on sex differences have been performed in several AD rodent models over the years. However, it has been challenging to study the menopause influence on AD due to lack of optimal models that mimic the human process. Recently, the rodent model of accelerated ovarian failure (AOF) was developed, which uniquely recapitulates human menopause, including a transitional peri-AOF period with irregular estrogen fluctuations and a post-AOF stage with low estrogen levels. This model has proven useful in hypertension and cognition studies with wild type animals. This review article will highlight the molecular mechanisms by which peri-menopause may influence the female brain vulnerability to AD and AD risk factors, such as hypertension and apolipoprotein E (APOE) genotype. Studies on these biological mechanisms together with the use of the AOF model have the potential to shed light on key molecular pathways underlying AD pathogenesis for the development of precision medicine approaches that take sex and hormonal status into account.

The Role of Estrogen in Brain and Cognitive Aging

There are 3 common physiological estrogens, of which estradiol (E2) is seen to decline rapidly over the menopausal transition. This decline in E2 has been associated with a number of changes in the brain, including cognitive changes, effects on sleep, and effects on mood. These effects have been demonstrated in both rodent and non-human preclinical models. Furthermore, E2 interactions have been indicated in a number of neuropsychiatric disorders, including Alzheimer's disease, schizophrenia, and depression. In normal brain aging, there are a number of systems that undergo changes and a number of these show interactions with E2, particularly the cholinergic system, the dopaminergic system, and mitochondrial function. E2 treatment has been shown to ameliorate some of the behavioral and morphological changes seen in preclinical models of menopause; however, in clinical populations, the effects of E2 treatment on cognitive changes after menopause are mixed. The future use of sex hormone treatment will likely focus on personalized or precision medicine for the prevention or treatment of cognitive disturbances during aging, with a better understanding of who may benefit from such treatment.

The potential reproductive toxicity of tannery effluent to the estrous cycle and ovarian follicular dynamics of female Swiss mice

Although the toxic effects of tannery effluent (TE) on tanning-industry workers have been reported in many studies, its effects on females' reproductive system are unknown. We aimed at evaluating the effects of direct contact with TE on the "emotional" status, estrous cycle (during 15 consecutive exposure days), and ovarian follicular dynamics of female Swiss mice at the end of the experiment to broaden the knowledge about the toxicity of this pollutant. The herein adopted exposure protocol simulated tanning-industry workers' exposure to TE. The test animals were subjected to 45 exposure days, for 1 h a day, 5 days a week (from Monday to Friday). Based on the collected data, female mice exposed to TE recorded high anxiety index in the elevated plus maze test, although we did not observe changes in their estrous cycle. The smaller total and specific number of ovarian follicles (types 1 to 6) and the higher frequency of degenerating follicles (atresic) in female mice exposed to TE marked the folliculogenesis reduction in them. Therefore, our study was the first to provide evidences that the exposure to TE can cause reproduction issues in female mice, as well as the first experimental insight about the impact of unhealthy work activities in tanning industries on women's reproductive system.

The opportunity for sexual selection and the evolution of non-responsiveness to pesticides, sterility inducers and contraceptives

We illustrate a method for delaying and possibly eliminating the evolution of non-responsiveness to the treatments now used to control pest populations. Using simulations and estimates of the variance in relative fitness, i.e., the opportunity for selection, in a rat-like mammal, we show that the selection responsible for the evolution of non-responsiveness to pesticides and sterility-inducers, is similar in its action to sexual selection, and for this reason can be orders of magnitude stronger than that which exists for untreated populations. In contrast, we show that when contraceptives are used to reduce the fertility of a pest species, with non-responders embedded within such populations, the opportunity for selection favoring non-responsiveness is reduced to that which is expected by chance alone. In pest species with separate sexes, we show that efforts to control pest populations or to mitigate selection favoring non-responsiveness, are likely to be ineffective when members of one sex are sterilized or killed. We also show that while mating preferences can impede the rate at which resistance evolves, they are more likely to accelerate this process, arguing against the use of sterile male approaches for controlling pests. Our results suggest that contraceptives are more effective at controlling pest populations and slowing the evolution of non-responsiveness than treatments that cause sterilization or death in target species. Furthermore, our results indicate that contraceptives that work differentially on each sex will be most effective in mitigating selection favoring non-responders. Our results have significant implications for the development and application of treatments to manage pests, now and into the future.

Depletion of follicles accelerated by combined exposure to phthalates and 4-vinylcyclohexene diepoxide, leading to premature ovarian failure in rats

Humans are at daily risk by simultaneous exposures to a broad spectrum of man-made chemicals in the commercial products. Several classes of chemicals have been shown to alter follicle development and reduce fertility, leading to premature ovarian failure (POF) in mammals. We investigate the synergistic effects of 4-vinylcyclohexene diepoxide (VCD) and phthalate, including di(2-ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP) and di-n-butyl phthalate (DBP) on POF. Combination exposure with VCD and phthalate significantly reduced the numbers of primary follicles. The expressions of Amh and Sohlh2 were significantly decreased in the combination groups. Serum Amh levels were significantly lower in the combination groups. Additionally, serum levels of follicle-stimulating hormone were significantly increased in combination groups. Taken together, exposure to phthalates promotes the depletion of follicular follicles and consequently increases the risk of premature menopause, and combined exposure of phthalates and VCD to early menopausal women is likely to aggravate the POF syndrome.

Effects of Estrogen Therapy on the Serotonergic System in an Animal Model of Perimenopause Induced by 4-Vinylcyclohexen Diepoxide (VCD)

Chronic exposure to 4-vinylcycloxene diepoxide (VCD) in rodents accelerates the natural process of ovarian follicular atresia modelling perimenopause in women. We investigated why estrogen therapy is beneficial for symptomatic women despite normal or high estrogen levels during perimenopause. Female rats (28 d) were injected daily with VCD or oil for 15 d; 55-65 d after the first injection, pellets of 17β-estradiol or oil were inserted subcutaneously. Around 20 d after, the rats were euthanized (control rats on diestrus and estradiol-treated 21 d after pellets implants). Blood was collected for hormone measurement, the brains were removed and dorsal raphe nucleus (DRN), hippocampus (HPC), and amygdala (AMY) punched out for serotonin (5-HT), estrogen receptor β (ERβ), and progesterone receptor (PR) mRNA level measurements. Another set of rats was perfused for tryptophan hydroxylase (TPH) immunohistochemistry in the DRN. Periestropausal rats exhibited estradiol levels similar to controls and a lower progesterone level, which was restored by estradiol. The DRN of periestropausal rats exhibited lower expression of PR and ERβ mRNA and a lower number of TPH cells. Estradiol restored the ERβ mRNA levels and number of serotonergic cells in the DRN caudal subregion. The 5-HT levels were lower in the AMY and HPC in peristropausal rats, and estradiol treatment increased the 5-HT levels in the HPC and also increased ERβ expression in this area. In conclusion, estradiol may improve perimenopause symptoms by increasing progesterone and boosting serotonin pathway from the caudal DRN to the dorsal HPC potentially through an increment in ERβ expression in the DRN.

Nanocarrier-mediated delivery of α-mangostin for non-surgical castration of male animals

The overpopulation of abandoned and stray companion animals has become a global crisis. The main purpose of this study was to develop a novel nanomedicine-based antifertility compound for non-surgical castration of male animals. Mangosteen (Garcinia mangostana L) pericarp extract has been shown to exhibit anti-fertility property. α-mangostin (AM)-loaded nanostructured lipid carrier (AM-NLC) was developed to improve male germ cell apoptosis. This study was conducted to investigate physicochemical properties of AM-NLC and determine the biological effects of AM-NLC on spermatogonia cells and testicular explants obtained from castrated testes. AM-NLC was produced through a hot homogenization technique. The negatively charged particle of AM-NLC was nano-sized with a narrow dispersity. AM-NLC exhibited antiproliferative activity towards spermatogonium cells. It induced apoptosis in the cells. In addition, AM-NLC exhibited anti-inflammatory activities in lipopolysaccharide-activated macrophages. Abnormal anatomy of seminiferous tubule was noted following treatment of testicular explant with AM-NLC. This nanomedicine-based sterilant would be a promising platform that may have utility in non-surgical castration of male animals by intra-testicular injection.

Cardiovascular Autonomic Responses in the VCD Rat Model of Menopause: Effects of Short- and Long-Term Ovarian Failure

After menopause, hypertension elevates the risk of cardiac diseases, one of the major causes of women's morbidity. The gradual depletion of ovarian follicles in rats, induced by 4-vinylcyclohexene diepoxide (VCD), is a model for studying the physiology of menopause. 4-Vinylcyclohexene diepoxide treatment leads to early ovarian failure (OF) and a hormonal profile comparable to menopause in humans. We have hypothesized that OF can compromise the balance between sympathetic and parasympathetic tones of the cardiovascular system, shifting toward dominance of the former. We aimed to study the autonomic modulation of heart and blood vessels and the cardiovascular reflexes in rats presenting short-term (80 days) or long-term (180 days) OF induced by VCD. Twenty-eight-day-old Wistar rats were submitted to VCD treatment (160 mg/kg, intraperitoneally) or vehicle (control) for 15 consecutive days and experiments were conducted at 80 or 180 days after the onset of treatment. Long-term OF led to an increase in the sympathetic activity to blood vessels and an impairment in the baroreflex control of the heart, evoked by physiological changes in arterial pressure. Despite that, long-term OF did not cause hypertension during the 180 days of exposure. Short-term OF did not cause any deleterious effect on the cardiovascular parameters analyzed. These data indicate that long-term OF does not disrupt the maintenance of arterial pressure homeostasis in rats but worsens the autonomic cardiovascular control. In turn, this can lead to cardiovascular complications, especially when associated with the aging process seen during human menopause.

Estrogens as neuroprotectants: Estrogenic actions in the context of cognitive aging and brain injury

There is ample empirical evidence to support the notion that the biological impacts of estrogen extend beyond the gonads to other bodily systems, including the brain and behavior. Converging preclinical findings have indicated a neuroprotective role for estrogen in a variety of experimental models of cognitive function and brain insult. However, the surprising null or even detrimental findings of several large clinical trials evaluating the ability of estrogen-containing hormone treatments to protect against age-related brain changes and insults, including cognitive aging and brain injury, led to hesitation by both clinicians and patients in the use of exogenous estrogenic treatments for nervous system outcomes. That estrogen-containing therapies are used by tens of millions of women for a variety of health-related applications across the lifespan has made identifying conditions under which benefits with estrogen treatment will be realized an important public health issue. Here we provide a summary of the biological actions of estrogen and estrogen-containing formulations in the context of aging, cognition, stroke, and traumatic brain injury. We have devoted special attention to highlighting the notion that estrogen appears to be a conditional neuroprotectant whose efficacy is modulated by several interacting factors. By developing criteria standards for desired beneficial peripheral and neuroprotective outcomes among unique patient populations, we can optimize estrogen treatments for attenuating the consequences of, and perhaps even preventing, cognitive aging and brain injury.

COMPROMISED FERTILITY IN FREE FEEDING OF WILD-CAUGHT NORWAY RATS (RATTUS NORVEGICUS) WITH A LIQUID BAIT CONTAINING 4-VINYLCYCLOHEXENE DIEPOXIDE AND TRIPTOLIDE

Wild rat pests in the environment cause crop and property damage and carry disease. Traditional methods of reducing populations of these pests involve poisons that can cause accidental exposures in other animals and humans. Fertility management with nonlethal chemicals would be an improved method of rat pest population control. Two chemicals known to target ovarian function in female rats are 4-vinylcyclohexene diepoxide (VCD) and triptolide. Additionally, triptolide impairs spermatogenesis in males. A liquid bait containing no active ingredients (control), or containing triptolide (0.001%) and VCD (0.109%; active) was prepared to investigate the potential use of these agents for wild rat pest population control. Liquid bait was made available to male (n = 8 control; n = 8 active) and female (n = 8 control; n = 8 active) Sprague Dawley rats ( Rattus norvegicus ) for oral consumption prior to breeding. Whereas, control bait-treated females produced normal-sized litters (10.0 ± 1.7 pups/litter), treated females delivered no pups. Wild Norway male (n = 20) and female (n = 20) rats ( Rattus norvegicus ) were trapped, individually housed, and one group given free access to control bait, one group to active bait. Following three cycles of treatment-matched mating pairs, females consuming control bait (control) produced normal litter sizes (9.73 ± 0.73 pups/litter). Females who had consumed active bait (treated) produced no litters on breeding cycles one and two; however, 2 of 10 females produced small litters on the third mating cycle. In a fourth breeding cycle, control females were crossmated with treated males, and treated females were crossmated with control males. In both groups, some dams produced litters, while others did not. The differences in response reflect a heterogeneity in return to cyclicity between females. These results suggest a potential approach to integrated pest management by compromising fertility, and could provide a novel alternative to traditional poisons for reducing populations of wild rat pests.

In female rat heart mitochondria, oophorectomy results in loss of oxidative phosphorylation

Oophorectomy in adult rats affected cardiac mitochondrial function. Progression of mitochondrial alterations was assessed at one, two and three months after surgery: at one month, very slight changes were observed, which increased at two and three months. Gradual effects included decrease in the rates of oxygen consumption and in respiratory uncoupling in the presence of complex I substrates, as well as compromised Ca²⁺ buffering ability. Malondialdehyde concentration increased, whereas the ROS-detoxifying enzyme Mn²⁺ superoxide dismutase (MnSOD) and aconitase lost activity. In the mitochondrial respiratory chain, the concentration and activity of complex I and complex IV decreased. Among other mitochondrial enzymes and transporters, adenine nucleotide carrier and glutaminase decreased. 2-Oxoglutarate dehydrogenase and pyruvate dehydrogenase also decreased. Data strongly suggest that in the female rat heart, estrogen depletion leads to progressive, severe mitochondrial dysfunction.

Glucose homeostasis in rats treated with 4-vinylcyclohexene diepoxide is not worsened by dexamethasone treatment

4-vinilcyclohexene diepoxide (4-VCD) causes premature ovarian failure and may result in estrogen deficiency, characterizing the transition to estropause in rodents (equivalent to menopause in women). Estropause/menopause is associated with metabolic derangements such as glucose intolerance and insulin resistance. Glucocorticoids (GCs) are known to exert diabetogenic effects. Thus, we aimed to investigate whether rats with premature ovarian failure are more prone to the diabetogenic effects of GC. For this, immature female rats received daily injections of 4-VCD [160mg/kg body weight (b.w.), intraperitoneally (i.p.)] for 15 consecutive days, whereas control rats received vehicle. After 168days of the completion of 4-VCD administration, rats were divided into 4 groups: CTL-received daily injections of saline (1mL/kg, b.w., i.p.) for 5days; DEX-received daily injections of dexamethasone (1mg/kg, b.w., i.p.) for 5days; VCD-treated as CTL group; VCD+DEX-treated as DEX group. Experiments and euthanasia occurred one day after the last dexamethasone injection. 4-VCD-treated rats exhibited ovary hypotrophy and reduced number of preantral follicles (p<0.05). Premature ovarian failure had no impact on the body weight gain or food intake, but both were reduced by the effects of dexamethasone. The increase in blood glucose, plasma insulin and triacylglycerol levels as well as the reduction in insulin sensitivity caused by dexamethasone treatment was not exacerbated in the VCD+DEX group of rats. Premature ovarian failure did change neither the hepatic content of glycogen and triacylglycerol nor the glycerol release from perigonadal adipose tissue. Glucose intolerance was observed in the VCD group after an ipGTT (p<0.05), but not after an oral glucose challenge. Glucose intolerance and compensatory pancreatic β-cell mass caused by GC were not modified by ovarian failure in the VCD+DEX group. We conclude that reduced ovarian function has no major implications on the diabetogenic effects promoted by GC treatment, indicating that other factors related to aging may make rats more vulnerable to GC side effects on glucose metabolism.

Schisandrae Fructus Reduces Symptoms of 4-Vinylcyclohexene Diepoxide-Induced Ovarian Failure in Mice

Menopause is associated with a decrease in the level of sex hormones such as ovarian estradiol and progesterone and can cause various symptoms such as depression, hot flash, fatigue, heart palpitations, and headache. Furthermore, there is a risk of developing complications such as osteoporosis, cardiovascular diseases, Alzheimer’s disease, and ovarian cancer. Schisandrae Fructus (SF) is widely used in Korean medicine as a cure for such complications. This study was conducted to evaluate the therapeutic effects of SF against menopause symptoms associated with follicle depletion caused by the industrial chemical 4-vinylcyclohexene diepoxide (VCD) in mice. VCD directly targets the preantral follicles. Mice were injected with VCD (160 mg/kg intraperitoneally) daily for 15 days and then with SF dosage 3 times/week for six weeks. To evaluate the effects of SF, body weight, tail skin temperature, uterine weight, lipid profile, and osteocalcin levels were measured. A decrease in body weight and tail skin temperature and an increase in uterine weight were observed upon SF treatment. Moreover, SF treatment significantly decreased total cholesterol, triglyceride, osteocalcin, and low-density lipoprotein levels and low-density/high-density lipoprotein ratio. These results suggest the potential use of SF in the treatment of menopausal symptoms in women.

Non-surgical sterilisation methods may offer a sustainable solution to feral horse (Equus caballus) overpopulation

Feral horses are a significant pest species in many parts of the world, contributing to land erosion, weed dispersal and the loss of native flora and fauna. There is an urgent need to modify feral horse management strategies to achieve public acceptance and long-term population control. One way to achieve this is by using non-surgical methods of sterilisation, which are suitable in the context of this mobile and long-lived species. In this review we consider the benefits of implementing novel mechanisms designed to elicit a state of permanent sterility (including redox cycling to generate oxidative stress in the gonad, random peptide phage display to target non-renewable germ cells and the generation of autoantibodies against proteins essential for conception via covalent modification) compared with that of traditional immunocontraceptive approaches. The need for a better understanding of mare folliculogenesis and conception factors, including maternal recognition of pregnancy, is also reviewed because they hold considerable potential in providing a non-surgical mechanism for sterilisation. In conclusion, the authors contend that non-surgical measures that are single shot and irreversible may provide a sustainable and effective strategy for feral horse control.

Cognitive changes across the menopause transition: A longitudinal evaluation of the impact of age and ovarian status on spatial memory

Cognitive changes that occur during mid-life and beyond are linked to both aging and the menopause transition. Studies in women suggest that the age at menopause onset can impact cognitive status later in life; yet, little is known about memory changes that occur during the transitional period to the postmenopausal state. The 4-vinylcyclohexene diepoxide (VCD) model simulates transitional menopause in rodents by depleting the immature ovarian follicle reserve and allowing animals to retain their follicle-deplete ovarian tissue, resulting in a profile similar to the majority of perimenopausal women. Here, Vehicle or VCD treatment was administered to ovary-intact adult and middle-aged Fischer-344 rats to assess the trajectory of cognitive change across time with normal aging and aging with transitional menopause via VCD-induced follicular depletion, as well as to evaluate whether age at the onset of follicular depletion plays a role in cognitive outcomes. Animals experiencing the onset of menopause at a younger age exhibited impaired spatial memory early in the transition to a follicle-deplete state. Additionally, at the mid- and post- follicular depletion time points, VCD-induced follicular depletion amplified an age effect on memory. Overall, these findings suggest that age at the onset of menopause is a critical parameter to consider when evaluating learning and memory across the transition to reproductive senescence. From a translational perspective, this study illustrates how age at menopause onset might impact cognition in menopausal women, and provides insight into time points to explore for the window of opportunity for hormone therapy during the menopause transition period. Hormone therapy during this critical juncture might be especially efficacious at attenuating age- and menopause- related cognitive decline, producing healthy brain aging profiles in women who retain their ovaries throughout their lifespan.

The VCD Mouse Model of Menopause and Perimenopause for the Study of Sex Differences in Cardiovascular Disease and the Metabolic Syndrome

In females, menopause, the cessation of menstrual cycling, is associated with an increase in risk for several diseases such as cardiovascular disease, osteoporosis, diabetes, the metabolic syndrome, and ovarian cancer. The majority of women enter menopause via a gradual reduction of ovarian function over several years (perimenopause) and retain residual ovarian tissue. The VCD mouse model of menopause (ovarian failure in rodents) is a follicle-deplete, ovary-intact animal that more closely approximates the natural human progression through perimenopause and into the postmenopausal stage of life. In this review, we present the physiological parameters of how to use the VCD model and explore the VCD model and its application into the study of postmenopausal disease mechanisms, focusing on recent murine studies of diabetic kidney disease, the metabolic syndrome, and hypertension.