Ovariectomy In Female Mice Research Articles

Sex hormone deficiency in male and female mice expressing the Alzheimer’s disease-associated risk-factor TREM2 R47H variant impacts the musculoskeletal system in a sex- and genotype-dependent manner

Abstract The R47H variant of the Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) is a risk factor for Alzheimer’s disease in humans and leads to lower bone mass accrual in female but not male 12-month-old mice. To determine whether, as with aging, gonadectomy results in sex-specific musculoskeletal effects, gonad removal or SHAM surgery were performed in 4-month-old TREM2R47H/+ mice and wild type (WT) male and female littermates (n = 10-12/group), with sexes analyzed separately. Body weight was lower in males, but higher in females after gonadectomy, independently of their genotype. Gonadectomy also lead to decreased BMD in males at all sites and in whole body (total) and spine in female mice for both genotypes. Total and femur BMD was lower in gonadectomized male mice 6-weeks post-surgery, independently of the genotype. On the other hand, BMD was only lower in ovariectomized WT but not TREM2R47H/+ mice in all sites measured at this time point. Bone formation and resorption markers levels were not affected by orchiectomy, whereas CTX was higher 3 weeks after surgery and P1NP showed a tendency towards lower values at the 6 weeks timepoint only in ovariectomized WT mice. μCT analyses showed no differences resulting from gonadectomy in structural parameters in femoral cortical bone for either sex, but lower tissue mineral density in males of either genotype 6 weeks post-surgery. Nevertheless, biomechanical properties were overall lower in gonadectomized males of either genotype, and only for WT ovariectomized mice. Distal femur cancellous bone structure was also affected by gonadectomy in a genotype- and sex-dependent manner, with genotype-independent changes in males, and only in WT female mice. Thus, expression of the TREM2 R47H variant minimally alters the impact of gonadectomy in the musculoskeletal system in males, whereas it partially ameliorates the consequences of ovariectomy in female mice.

A potential treatment with phytoestrogens: A literature review of experimental models on female rat’s reproductive health

Introduction: Phytoestrogens are nonsteroidal substances produced from plants with biological properties such as estrogen. The two main types of phytoestrogens are flavonoids and non-flavonoids. Flavonoids, including isoflavones, are among the most estrogenic compounds, and due to their structural similarities, they can bind to estrogen receptors. Isoflavones have been found in various foods, including fruits, vegetables, sprouts, seeds, and oilseeds (including flaxseeds). This review focuses on plants phytoestrogens that contain flavonoids, isoflavones, daidzein, and genistein. In addition, isoflavones can also be considered endocrine disruptors with the possibility of negative effects on the state of health in certain parts of the population or environment. This literature review will include phytoestrogen-rich crop yields on the reproductive health of mice. Method Systematic review: Literature searches are conducted on databases such as PubMed, ScienceDirect, Google Scholar, and Cochrane, with time limits. From 2014 to 2024, searches were carried out on this database, considering studies involving herbs, phytoestrogens, isoflavones, and genistein in ovariectomy rat’s model (OVX). The study found that plants rich in phytoestrogens can overcome post-ovariectomy complaints, increase estrogen levels, and increase normal cell proliferation. This herb is used as an effective alternative therapy in treating post-ovariectomy complaints. Result: The search results found 2,401 studies on phytoestrogens and hypoestrogenics in the reproductive organs. Conclusion: Phytoestrogens have active compounds that can improve the reproductive system after ovariectomy in female mice.

Sex-related differences in SIRT3-mediated mitochondrial dynamics in renal ischemia/reperfusion injury

The prevalence of renal ischemia/reperfusion injury (IRI) in premenopausal women is considerably lower than that in age-matched men. This suggests that sex-related differences in mitochondrial function and homeostasis may contribute to sexual dimorphism in renal injury, though the mechanism remains unclear. Mouse model of unilateral left renal IRI with contralateral kidney enucleation, Ovariectomy in female mice, and a human embryonic kidney (HEK) cell model of hypoxia-reoxygenation were used to study how estrogen affects the sexual dimorphism of renal IRI through SIRT3 in vitro and in vivo, respectively. Here, we demonstrate differential expression of renal SIRT3 may induce sexual dimorphism in IRI using the renal IRI model. Higher SIRT3 level in female mice was associated with E2-induced protection of renal tubular epithelium, reduced mitochondrial reactive oxygen species (ROS), and IRI resistance. In hypoxia-reoxygenated HEK cells, SIRT3 knockdown increased oxidative stress, shifted the interconnected mitochondrial network toward fission, exacerbated hypoxia/reoxygenation-induced endoplasmic reticulum stress (ERS), and abolished the protective effects of E2 on IRI. Mechanistically, the SIRT3 level is E2-dependent and that E2 increases the SIRT3 protein level via estrogen receptor. SIRT3 targeted an i-AAA protease, yeast mitochondrial AAA metalloprotease (YME1L1), and hydrolyzed long optic atrophy 1 (L-OPA) to short-OPA1 (S-OPA1) by deacetylating YME1L1, regulating mitochondrial dynamics toward fusion to reduce oxidative stress and ERS. These findings explored the mechanism by how estrogen alleviates renal IRI and providing a basis for potential therapeutic interventions targeting SIRT3.

OR12-06 Hypothalamic Adgrl1 Is A Potential Glucoreceptor Involved In Regulating Energy Balance, Glucose Homeostasis, And Leptin Sensitivity In Mice

Abstract Disclosure: D.J. Samuel: None. T.S. Faniyan: None. M.U. Raza: None. S. Bathina: None. K.H. Chhabra: None. The hypothalamus regulates energy and glucose homeostasis by influencing glucose-stimulated insulin secretion, insulin sensitivity, and activating the hypoglycemia counterregulatory response. Although hypothalamic glucose transporters coupled with glucose metabolism are involved in mediating some of these effects, it is unknown whether a plasma membrane receptor that directly binds to glucose can contribute to hypothalamic glucose signaling. We used affinity chromatography and biotin-labeled glucose to enrich glucose-binding plasma membrane proteins/receptors in the mouse hypothalamus and then performed proteomic analyses. Adhesion G-protein Coupled Receptor L1 (Adgrl1) was a top candidate as a potential glucoreceptor. Therefore, we generated Adgrl1loxp/loxp mice to knockout Adgrl1 in the ventromedial hypothalamus (VMH; a region known for glucose sensing) using the Cre-Lox system to determine the role of Adgrl1VMH in glucose homeostasis, energy balance, and leptin sensitivity. We measured body weight, food intake, 6h fasting blood glucose and plasma insulin levels. We also determined leptin sensitivity in the Adgrl1VMH deficient mice. We observed that 24 weeks old male Adgrl1VMH deficient mice had higher (p<0.05) body weight (49 ±3.6 vs 35 ±1.3 g), blood glucose (210 ±4 vs 180 ±5 mg/dl), plasma insulin levels (2.92 ±0.24 vs 1.63 ±0.09 ng/ml), and leptin levels (21.11 ±1.72 vs 8.38 ±0.80 ng/ml) compared to their control littermates. Hyperinsulinemia and hyperleptinemia persisted in the Adgrl1VMH knockout mice even when they were weight-matched to their littermate controls, indicating the direct role of Adgrl1VMH in regulating plasma insulin and leptin levels. Ovariectomy in female mice was necessary to unmask the effects of Adgrl1VMH deficiency on energy and glucose homeostasis. To assess acute leptin sensitivity, we injected Adgrl1VMH deficient mice and their littermate control mice with recombinant mouse leptin (5 mg/Kg, i.p., twice a day for two days), and monitored their body weight and food intake. Male Adgrl1VMH deficient mice were more susceptible (p<0.05) to leptin mediated decrease in food intake (-1 ±0.1 vs -0.5 ±0.005, g/day; these values are relative to each group’s corresponding baseline food intake) than their littermate controls. Decrease in body weight was similar in both groups with this acute leptin treatment. These findings suggest that Adgrl1VMH is essential in regulating energy and glucose homeostasis in a sex-specific manner. Moreover, Adgrl1VMH contributes to leptin’s acute effects on food intake. Therefore, hypothalamic Adgrl1 could be a target to enhance leptin sensitivity in future therapies for treating type 2 diabetes and obesity. Presentation: Friday, June 16, 2023

Isoflavone-Enriched Soybean Leaves (Glycine Max) Alleviate Cognitive Impairment Induced by Ovariectomy and Modulate PI3K/Akt Signaling in the Hippocampus of C57BL6 Mice.

(1) Background: The estrogen decline during perimenopause can induce various disorders, including cognitive impairment. Phytoestrogens, such as isoflavones, lignans, and coumestans, have been tried as a popular alternative to avoid the side effects of conventional hormone replacement therapy, but their exact mechanisms and risk are not fully elucidated. In this study, we investigated the effects of isoflavone-enriched soybean leaves (IESLs) on the cognitive impairment induced by ovariectomy in female mice. (2) Methods: Ovariectomy was performed at 9 weeks of age to mimic menopausal women, and the behavior tests for cognition were conducted 15 weeks after the first administration. IESLs were administered for 18 weeks. (3) Results: The present study showed the effects of IESLs on the cognitive function in the OVX (ovariectomized) mice. Ovariectomy markedly increased the body weight and fat accumulation in the liver and perirenal fat, but IESL treatment significantly inhibited them. In the behavioral tests, ovariectomy impaired cognitive functions, but administration of IESLs restored it. In addition, in the OVX mice, administration of IESLs restored decreased estrogen receptor (ER) β and PI3K/Akt expression in the hippocampus. (4) Conclusions: The positive effects of IESLs on cognitive functions may be closely related to the ER-mediated PI3/Akt signaling pathway in the hippocampus.

RANK deletion in neuropeptide Y neurones attenuates oestrogen deficiency-related bone loss.

The RANKL pathway is known to be an important aspect of the pathogenesis of oestrogen deficiency-induced bone loss. RANK deletion specifically in neuropeptide Y (NPY) neurones has been shown to enhance the ability of the skeleton to match increases in body weight caused by high-fat diet feeding, likely via the modulation of NPY levels. In the present study, we used ovariectomy in female mice to show that RANK deletion in NPY neurones attenuates bone loss caused by long-term oestrogen deficiency, particularly in the vertebral compartment. Ovariectomy led to a reduction in NPY expression levels in the arcuate nucleus of NPYcre/+ ;RANKlox/lox mice compared to NPYcre/+ ;RANKlox/+ controls. Because NPY deficient mice also displayed a similar protection against ovariectomy-induced bone loss, modulation of hypothalamic NPY signalling is the likely mechanism behind the protection from bone loss in the NPYcre/+ ;RANKlox/lox mice.

Chronic UVB-irradiation actuates perpetuated dermal matrix remodeling in female mice: Protective role of estrogen.

Chronic UVB-exposure and declined estradiol production after menopause represent important factors leading to extrinsic and intrinsic aging, respectively. Remodeling of the extracellular matrix (ECM) plays a crucial role in both responses. Whether the dermal ECM is able to recover after cessation of UVB-irradiation in dependence of estradiol is not known, however of relevance when regarding possible treatment options. Therefore, the endogenous sex hormone production was depleted by ovariectomy in female mice. Half of the mice received estradiol substitution. Mice were UVB-irradiated for 20 weeks and afterwards kept for 10 weeks without irradiation. The collagen-, hyaluronan- and proteoglycan- (versican, biglycan, lumican) matrix, collagen cleavage products and functional skin parameters were analyzed. The intrinsic aging process was characterized by increased collagen fragmentation and accumulation of biglycan. Chronic UVB-irradiation additionally augmented the lumican, versican and hyaluronan content of the dermis. In the absence of further UVB-irradiation the degradation of collagen and accumulation of biglycan in the extrinsically aged group was perpetuated in an excessive matter. Whereas estradiol increased the proteoglycan content, it reversed the effects of the perpetuated extrinsic response on collagen degradation. Suspension of the intrinsic pathway might therefore be sufficient to antagonize UVB-evoked long-term damage to the dermal ECM.

Sex-dependence of anxiety-like behavior in cannabinoid receptor 1 (Cnr1) knockout mice

Epidemiological data suggest women are at increased risk for developing anxiety and depression, although the mechanisms for this sex/gender difference remain incompletely understood. Pre-clinical studies have begun to investigate sex-dependent emotional learning and behavior in rodents, particularly as it relates to psychopathology; however, information about how gonadal hormones interact with the central nervous system is limited. We observe greater anxiety-like behavior in male mice with global knockout of the cannabinoid 1 receptor (Cnr1) compared to male, wild-type controls as measured by percent open arm entries on an elevated plus maze test. A similar increase in anxiety-like behavior, however, is not observed when comparing female Cnr1 knockouts to female wild-type subjects. Although, ovariectomy in female mice did not reverse this effect, both male and female adult mice with normative development were sensitive to Cnr1 antagonist-mediated increases in anxiety-like behavior. Together, these data support an interaction between sex, potentially mediated by gonadal hormones, and the endocannabinoid system at an early stage of development that is critical for establishing adult anxiety-like behavior.

Endogenous Androgen Deficiency Enhances Diet-Induced Hypercholesterolemia and Atherosclerosis in Low-Density Lipoprotein Receptor-Deficient Mice

Despite numerous clinical and animal studies, the role of sex steroid hormones on lipoprotein metabolism and atherosclerosis remain controversial. We sought to determine the effects of endogenous estrogen and testosterone on lipoprotein levels and atherosclerosis using mice fed a low-fat diet with no added cholesterol. Male and female low-density lipoprotein receptor-deficient mice were fed an open stock low-fat diet (10% of kcals from fat) for 2, 4, or 17 weeks. Ovariectomy, orchidectomy, or sham surgeries were performed to evaluate the effects of the presence or absence of endogenous hormones on lipid levels, lipoprotein distribution, and atherosclerosis development. Female mice fed the study diet for 17 weeks had a marked increase in levels of total cholesterol, triglycerides, apolipoprotein-B containing lipoproteins, and atherosclerosis compared with male mice. Surprisingly, ovariectomy in female mice had no effect on any of these parameters. In contrast, castration of male mice markedly increased total cholesterol concentrations, triglycerides, apolipoprotein B-containing lipoproteins, and atherosclerotic lesion formation compared with male and female mice. These data suggest that endogenous androgens protect against diet-induced increases in cholesterol concentrations, formation of proatherogenic lipoproteins, and atherosclerotic lesions formation. Conversely orchidectomy, which decreases androgen concentrations, promotes increases in cholesterol concentrations, proatherogenic lipoprotein formation, and atherosclerotic lesion formation in low-density lipoprotein receptor-deficient mice in response to a low-fat diet.

Sex differences in murine susceptibility to systemic viral infections

Increased susceptibility to autoimmunity in females is often viewed as the consequence of enhanced immunoreactivity providing superior protection against infections. We paradoxically observed greater mortality in female compared to male mice during systemic viral infections with three large double-stranded DNA viruses (herpes simplex virus type I [HSV], murine cytomegalovirus [MCMV], and vaccinia virus [VV]). Indeed, female mice were 27-fold more susceptible to infection with HSV than male mice. Elimination of estrogen by ovariectomy in female mice or addition of estrogen to castrated male mice only partially eliminated the observed sex differences following HSV infection. However, the differences observed in survival between female and male mice were nearly abrogated in the absence of type I interferon receptor signaling and substantially mitigated in absence of DAP12 signaling. Interestingly, the sex-specific impact of type I interferon receptor and DAP12 signaling differentially influenced survival during systemic viral infections with type I interferon receptor signaling enhancing male survival and DAP12 signaling increasing the susceptibility of female mice. These results have potential implications for the sex disparities observed in human autoimmune disorders.

Factors producing a menopausal depressive-like state in mice following ovariectomy

Bilateral ovariectomy in female mice produces a menopausal depressive-like state but the factors responsible for the phenomenon are unknown. We elucidated methodological issues related to establishing this mouse model and investigated a possible mechanism underlying the depressive-like state of ovariectomized mice. We removed both ovaries of female ICR mice at 9 weeks of age. Changes in the immobility time during the forced swimming test as a function of the time interval between ovariectomy and behavioral testing were determined on nine different days after surgery. To assess behavioral specificity, the elevated plus-maze (EPM) behavior and spontaneous activity were measured. With respect to the effect of ovariectomy on the immobility time, we compared ICR mice with three other strains of mice (C57BL/6J, DBA/2N, and CD-1). Finally, we investigated the effects of (-)-2,5-dimethoxy-4-iodoamphetamine (DOI) and (+/-)-8-hydroxy-2-(N,N-di-n-propylamino) tetralin (8-OH-DPAT) on the immobility time of ovariectomized mice. A significant effect on the prolongation of immobility was observed between 12 and 18 days after ovariectomy. Ovariectomy did not alter either the EPM behavior or spontaneous activity. Of the four strains of mice, only DBA mice did not show any significant prolongation of immobility after ovariectomy. Acute or chronic treatment with DOI (0.5 or 1.0 mg kg(-1)) significantly prevented the prolongation of immobility time, whereas acute and chronic treatments with 8-OH-DPAT (0.05, 0.5, or 1.0 mg kg(-1)) were ineffective. The present findings have potentially important implications for evaluating a candidate substance for the management of mood disorders in menopausal women.

Studies of GH secretion in mice by a homologous radioimmunoassay for mouse GH.

A sensitive homologous radioimmunoassay for mouse GH capable of measuring concentrations of GH as low as 1 ng/ml of mouse serum has been developed. This assay has been used to study GH secretion in C3H mice under several physiological conditions. Newborn mice possessed very high concentration of GH in serum which persisted for two weeks. Adult male mice had more GH in their pituitary (66.9 μg/mg) and serum (12.0 ng/ml) than comparable females (48.9 μg/mg; 3.4 ng/ml). Ovariectomy in female mice increased pituitary and serum concentrations of GH to male levels whereas stilbestrol administration decreased it. Orchiectomy or stilbestrol treatment of male mice resulted in decreased GH levels. During the estrous cycle, maximum levels of GH were attained during proestrus. Insulininduced hypoglycemia or treatment with L—dopa failed to induce rise in serum concentrations of GH in mice.(Endocrinology 91: 784, 1972)