Manipulation of Ovarian Function Significantly Influenced Sarcopenia in Postreproductive-Age Mice

Chronological and reproductive aging-associated changes in resistance to oxidative stress in post-reproductive female mice

Effort toward reproduction is often thought to negatively influence health and survival. Reproduction has been shown to influence metabolism, but the pathways and mechanisms have yet to be thoroughly elucidated. In the current experiments, our aim was to dissect the role of young and old ovarian tissues in the response to oxidative stress, through changes in liver oxidative stress response proteins. Liver proteins were analyzed in control mice at 4, 13, and 27 months of age and compared to 23-month-old mice which received young ovarian tissue transplants (intact or follicle-depleted) at 13 months of age. In control mice, of the 29 oxidative stress response proteins measured, 31% of the proteins decreased, 52% increased, and 17% were unchanged from 13 to 27 months. The greatest changes were seen during the period of reproductive failure, from 4 to 13 months of age. In transplanted mice, far more proteins were decreased from 13 to 23 months (93% in follicle-containing young ovary recipients; 62% in follicle-depleted young ovary recipients). Neither transplant group reflected changes seen in control mice between 13 and 27 months. Estradiol levels in transplant recipient mice were not increased compared with age-matched control mice. The current results suggest the presence of a germ cell- and estradiol-independent ovarian influence on aging-associated changes in the response to oxidative stress, which is manifest differently in reproductive-aged adults and post-reproductive-aged mice. The results presented here separate chronological and ovarian aging and the influence of estradiol in the response to aging-associated oxidative stress and support a novel, estradiol-independent role for the ovary in female health and survival.

Estradiol-independent restoration of T-cell function in post-reproductive females

Aging leads to a general decline in protective immunity. The most common age-associated effects are in seen T-cell mediated immune function. Adult mice whose immune systems show only moderate changes in T-cell subsets tend to live longer than age-matched siblings that display extensive T-cell subset aging. Importantly, at the time of reproductive decline, the increase in disease risks in women significantly outpace those of men. In female mice, there is a significant decline in central and peripheral naïve T-cell subsets at the time of reproductive failure. Available evidence indicates that this naïve T-cell decline is sensitive to ovarian function and can be reversed in post-reproductive females by transplantation of young ovaries. The restoration of naïve T-cell subsets due to ovarian transplantation was impressive compared with post-reproductive control mice, but represented only a partial recovery of what was lost from 6 months of age. Apparently, the influence of ovarian function on immune function may be an indirect effect, likely moderated by other physiological functions. Estradiol is significantly reduced in post-reproductive females, but was not increased in post-reproductive females that received new ovaries, suggesting an estradiol-independent, but ovarian-dependent influence on immune function. Further evidence for an estradiol-independent influence includes the restoration of immune function through the transplantation of young ovaries depleted of follicles and through the injection of isolated ovarian somatic cells into the senescent ovaries of old mice. While the restoration of naïve T-cell populations represents only a small part of the immune system, the ability to reverse this important functional parameter independent of estradiol may hold promise for the improvement of post-reproductive female immune health. Further studies of the non-reproductive influence of the ovary will be needed to elucidate the mechanisms of the relationship between the ovary and health.

Aging-associated changes in motor function are ovarian somatic tissue-dependent, but germ cell and estradiol independent in post-reproductive female mice exposed to young ovarian tissue

A critical mediator of evolution is natural selection, which operates by the divergent reproductive success of individuals and results in conformity of an organism with its environment. Reproductive function has evolved to support germline transmission. In mammalian ovaries, this requires healthy, active gonad function, and follicle development. However, healthy follicles do not contribute to germline transmission in a dead animal. Therefore, support of the health and survival of the organism, in addition to fertility, must be considered as an integral part of reproductive function. Reproductive and chronological aging both impose a burden on health and increase disease rates. Tremors are a common movement disorder and are often correlated with increasing age. Muscle quality is diminished with age and these declines are gender-specific and are influenced by menopause. In the current experiments, we evaluated aging-associated and reproduction-influenced changes in motor function, utilizing changes in tremor amplitude and grip strength. Tremor amplitude was increased with aging in normal female mice. This increase in tremor amplitude was prevented in aged female mice that received ovarian tissue transplants, both in mice that received germ cell-containing or germ cell-depleted ovarian tissue. Grip strength was decreased with aging in normal female mice. This decrease in grip strength was prevented in aged female mice that received either germ cell-containing or germ cell-depleted tissue transplants. As expected, estradiol levels decreased with aging in normal female mice. Estradiol levels did not change with exposure to young ovarian tissues/cells. Surprisingly, estradiol levels were not increased in aged females that received ovaries from actively cycling, young donors. Overall, tremor amplitude and grip strength were negatively influenced by aging and positively influenced by exposure to young ovarian tissues/cells in aged female mice, and this positive influence was independent of ovarian germ cells and estradiol levels. These findings provide a strong incentive for further investigation of the influence of ovarian somatic tissue on health. In addition, changes in tremor amplitude may serve as an additional marker of biological age.

The interrelationship between female reproductive aging and survival

The link between survival and reproductive function is demonstrated across many species and is under both long-term evolutionary pressures and short-term environmental pressures. Loss of reproductive function is common in mammals and is strongly correlated with increased rates of disease in both males and females. However, the reproduction-associated change in disease rates is more abrupt and more severe in women, who benefit from a significant health advantage over men until the age of menopause. Young women with early ovarian failure also suffer from increased disease risks, further supporting the role of ovarian function in female health. Contemporary experiments where the influence of young ovarian tissue has been restored in post-reproductive-aged females with surgical manipulation were found to increase survival significantly. In these experiments, young, intact ovaries were used to replace the aged ovaries of females that had already reached reproductive cessation. As has been seen previously in primitive species, when the young mammalian ovaries were depleted of germ cells prior to transplantation to the post-reproductive female, survival was increased even further than with germ cell-containing young ovaries. Thus, extending reproductive potential significantly increases survival and appears to be germ cell and ovarian hormone-independent. The current review will discuss historical and contemporary observations and theories that support the link between reproduction and survival and provide hope for future clinical applications to decrease menopause-associated increases in disease risks.

Sarcopenia as a Predictor of Prognosis in Early Stage Ovarian Cancer

BACKGROUND

To identify sarcopenia as a predictive prognostic factor of ovarian cancer in terms of survival outcome in patients with early-stage ovarian cancer.

METHODS

Data of Konkuk University Medical Center from March 2002 to December 2017 were reviewed retrospectively. Eighty-two patients who underwent surgery due to early-stage (International Federation of Gynecology and Obstetrics stage I/II) ovarian cancer and had computed tomography (CT) images taken at the initial diagnosis were included. The initial CT scan images were analyzed with SliceOmatic software (TomoVision). A sarcopenia cutoff value was defined as a skeletal muscle index of ≤ 38.7 cm²/m². Overall survival (OS) times were compared according to the existence of sarcopenia, and subgroup analyses were performed.

RESULTS

A Kaplan-Meier analysis showed a significant survival disadvantage for patients with early-stage ovarian cancer when they had sarcopenia (P < 0.001; log-rank test). Sarcopenia remained a significant prognostic factor for OS in early-stage ovarian cancer, in a Cox proportional hazards model regression analysis (HR, 21.9; 95% CI, 2.0-199.9; P = 0.006).

CONCLUSION

This study demonstrated that sarcopenia was predictive of OS in patients with early-stage ovarian cancer. Further prospective studies with a larger number of patients are warranted to determine the extent to which sarcopenia can be used as a prognostic factor in ovarian cancer.

A toolbox for the longitudinal assessment of healthspan in aging mice

The number of people aged over 65 is expected to double in the next 30 years. For many, living longer will mean spending more years with the burdens of chronic diseases such as Alzheimer's disease, cardiovascular disease, and diabetes. Although researchers have made rapid progress in developing geroprotective interventions that target mechanisms of aging and delay or prevent the onset of multiple concurrent age-related diseases, a lack of standardized techniques to assess healthspan in preclinical murine studies has resulted in reduced reproducibility and slow progress. To overcome this, major centers in Europe and the United States skilled in healthspan analysis came together to agree on a toolbox of techniques that can be used to consistently assess the healthspan of mice. Here, we describe the agreed toolbox, which contains protocols for echocardiography, novel object recognition, grip strength, rotarod, glucose tolerance test (GTT) and insulin tolerance test (ITT), body composition, and energy expenditure. The protocols can be performed longitudinally in the same mouse over a period of 4-6 weeks to test how candidate geroprotectors affect cardiac, cognitive, neuromuscular, and metabolic health.

Extension of longevity and reduction of inflammation is ovarian-dependent, but germ cell-independent in post-reproductive female mice

Cardiovascular disease, rare in premenopausal women, increases sharply at menopause and is typically accompanied by chronic inflammation. Previous work in our laboratory demonstrated that replacing senescent ovaries in post-reproductive mice with young, actively cycling ovaries restored many health benefits, including decreased cardiomyopathy and restoration of immune function. Our objective here was to determine if depletion of germ cells from young transplanted ovaries would alter the ovarian-dependent extension of life and health span. Sixty-day-old germ cell-depleted and germ cell-containing ovaries were transplanted to post-reproductive, 17-month-old mice. Mean life span for female CBA/J mice is approximately 644 days. Mice that received germ cell-containing ovaries lived 798 days (maximum = 815 days). Mice that received germ cell-depleted ovaries lived 880 days (maximum = 1046 days), 29% further past the time of surgery than mice that received germ cell-containing ovaries. The severity of inflammation was reduced in all mice that received young ovaries, whether germ cell-containing or germ cell-depleted. Aging-associated inflammatory cytokine changes were reversed in post-reproductive mice by 4 months of new-ovary exposure. In summary, germ cell depletion enhanced the longevity-extending effects of the young, transplanted ovaries and, as with germ cell-containing ovaries, decreased the severity of inflammation, but did so independent of germ cells. Based on these observations, we propose that gonadal somatic cells are programed to preserve the somatic health of the organism with the intent of facilitating future germline transmission. As reproductive potential decreases or is lost, the incentive to preserve the somatic health of the organism is lost as well.

Decreased Sarcopenia in Aged Females with Young Ovary Transplants was Preserved in Mice that Received Germ Cell-Depleted Young Ovaries

Previously, transplantation of young, cycling, ovaries increased life and health span in post-reproductive female mice. The current study addressed the influence of ovarian germ cells in the improvement in health by performing transplantations of young, germ cell-depleted ovaries. The purpose of this study is to further the understanding of reproductive influences on aging health. Control mice were grouped by age. Treatment mice were age-matched and received either germ cell depleted ovaries or germ cell containing ovaries at 400 days of age. All groups underwent health span assays until sacrifice (treatment and age-matched control groups were between 680 and 700 days). Body composition results displayed an improvement of body composition in both treatment groups, compared to the controls, but no significant difference between the germ cell-depleted or germ cell-containing groups. Grip test results showed no improvement in musculoskeletal endurance and no change to mild loss of grip strength with both transplant groups compared to control groups. The research presented here suggests that reproductive status has a positive influence in post-reproductive health. A portion of this influence may be germ cell independent.

Orthotopic Ovarian Transplantation Procedures to Investigate the Life- and Health-span Influence of Ovarian Senescence in Female Mice

Ovarian transplantation was first conducted at Utah State University in 1963. In more recent work, heterochronic transplantation of mammalian ovaries is being used to investigate the health-protective effects of young ovaries in young females. The current procedures employ an orthotopic transplantation method, where allogenic ovaries are transplanted back to their original position in the ovarian bursa. This is in contrast to the more commonly used heterotopic transplantation of ovaries/ovarian tissue subcutaneously or under the kidney capsule. All three locations provide efficient revascularization of the transplanted tissues. However, orthotopic transplantation provides the ovary with the most natural signaling environment and is the only procedure that provides the opportunity for the animal to reproduce naturally post-operatively. One must take care to remove all endogenous ovarian tissue during the ovariectomy procedure. If any endogenous tissue remains or if only one ovary is removed, the transplanted tissue will remain dormant until the existing tissue becomes senescent. While revascularization of the transplanted ovaries occurs very quickly, the transplant recipient can take a considerable amount of time to adapt to a new hypothalamic/pituitary/gonadal/adrenal (HPG/A) axis signaling regime associated with the transplanted tissue. This normally takes about 100 days in the mouse. Therefore, transplantation experiments should be designed to accommodate this adaptation period. Typical results with ovarian transplantation will include changes in the health of the recipient that reflect the age of the transplanted ovary, rather than the chronological age of the recipient.