A novel epigenetic clock for rhesus macaques unveils an association between early life adversity and epigenetic age acceleration.

Because DNA methylation changes reliably with age, machine learning models called epigenetic clocks can estimate an individual's age based on their DNA methylation profile. This epigenetic measure of age can deviate from one's true age, and the difference between the epigenetic age and true age, known as epigenetic age acceleration (EAA), has been found to directly correlate with morbidity and mortality in adults. Emerging evidence suggests that EAA is also associated with aberrant health outcomes in children, making epigenetic clocks useful tools for studying aging and development. We developed two highly accurate epigenetic clocks for the rhesus macaque, utilizing 1,008 blood samples from 690 macaques between 2 days and 23.4 years of age with diverse genetic backgrounds and exposure to environmental conditions. The first clock, which is trained on all samples, achieves a Pearson correlation between true age and predicted age of 0.983 and median absolute error of 0.210 years. To study phenotypes during development, the second clock is optimized for macaques younger than 6 years and achieves a Pearson correlation of 0.974 and a median absolute error of 0.148 years. Using the latter clock, we investigated whether epigenetic aging is affected by early life adversity in the form of infant maltreatment. Our data suggests that maltreatment and increased hair cortisol levels are associated with epigenetic age acceleration right after the period of maltreatment.

Time of trauma prospectively affects PTSD symptom severity: The impact of circadian rhythms and cortisol.

A key feature of posttraumatic stress disorder (PTSD) is a disruption of hypothalamic-pituitary-adrenal (HPA) axis feedback sensitivity and cortisol levels. Despite known diurnal rhythmicity of cortisol, there has been little exploration of the circadian timing of the index trauma and consequent cortisol release. Stress-related glucocorticoid pulses have been shown to shift clocks in peripheral organs but not the suprachiasmatic nucleus, uncoupling the central and peripheral clocks. A sample of 425 participants was recruited in the Emergency Department following a DSM-IV-TR Criterion A trauma. The Zeitgeber time of the trauma was indexed in minutes since sunrise, which was hypothesized to covary with circadian blood cortisol levels (high around sunrise and decreasing over the day). Blood samples were collected M(SD)= 4.0(4.0) hours post-trauma. PTSD symptoms six months post-trauma were found to be negatively correlated with trauma time since sunrise (r(233) = -0.15, p = 0.02). The effect remained when adjusting for sex, age, race, clinician-rated severity, education, pre-trauma PTSD symptoms, and time of the blood draw (ß = -0.21, p = 0.00057). Cortisol levels did not correlate with blood draw time, consistent with a masking effect of the acute stress response obscuring the underlying circadian rhythm. Interactions between trauma time and expression of NPAS2 (punadjusted=0.042) and TIMELESS (punadjusted=0.029) predicted six-month PTSD symptoms. The interaction of trauma time and cortisol concentration was significantly correlated with the expression of PER1 (padjusted=0.029). The differential effect of time of day on future symptom severity suggests a role of circadian effects in PTSD development, potentially through peripheral clock disruption.

Impact of 6 month conjugated equine estrogen versus estradiol-treatment on biomarkers and enriched gene sets in healthy mammary tissue of non-human primates.

OBJECTIVE: To identify distinctly regulated gene markers and enriched gene sets in breast tissue of cynomolgus monkeys (Macaca fascicularis) treated for six months with either conjugated equine estrogens (CEE) or estradiol (E2) by analysis of corresponding mRNA levels of genes associated with breast development, carcinogenesis, apoptosis and immune regulation. Additionally, translation of three nuclear markers was analyzed. METHODS: RNA from breast biopsies and necropsies was isolated from two independent study trials from Ethun et al. (CEE) and Foth et al. (E2) after 6 month of treatment duration. RNA was subjected to qRT-PCR and MicroArray analysis. Immunohistochemical stainings were performed for the estrogen receptor alpha subunit (ERa), the progesterone receptor (PGR) and the proliferation marker Ki67. RESULTS: We identified a total of 36 distinctly enriched gene sets. Thirty-one were found in the CEE treatment group and five were found in the E2 treatment group, with no overlap. Furthermore, two individual genes IGFBP1 and SGK493 were upregulated in CEE treated animals. Additional targeted qRT-PCR analysis of ten specific estrogen-related genes showed upregulation of three genes (TFF1, PGR and GREB1) after CEE treatment, respectively one gene (TFF1) after E2 treatment. Immunohistochemical stains of breast biopsies showed a significant increase in expression of the PGR marker after CEE treatment. CONCLUSIONS: In this study we identified enriched gene sets possibly induced by CEE or E2 treatment in various processes associated with cancer biology and immunology. This preliminary translational data supports the concept that different estrogen types have different effects on healthy breast tissue and may help generate hypotheses for future research.

Sex Differences in Peritraumatic Inflammatory Cytokines and Steroid Hormones Contribute to Prospective Risk for Nonremitting Posttraumatic Stress Disorder.

Women are at higher risk for developing posttraumatic stress disorder (PTSD) compared to men, yet little is known about the biological contributors to this sex difference. One possible mechanism is differential immunological and neuroendocrine responses to traumatic stress exposure. In the current prospective study, we aimed to identify whether sex is indirectly associated with the probability of developing nonremitting PTSD through pro-inflammatory markers and whether steroid hormone concentrations influence this effect. Female (n = 179) and male (n = 197) trauma survivors were recruited from an emergency department and completed clinical assessment within 24 h and blood samples within ∼three hours of trauma exposure. Pro-inflammatory cytokines (IL-6, IL-1 ß , TNF, IFNγ), and steroid hormone (estradiol, testosterone, progesterone, cortisol) concentrations were quantified in plasma. Compared to men, women had a higher probability of developing nonremitting PTSD after trauma (p = 0.04), had lower pro-inflammatory cytokines and testosterone (p's<0.001), and had higher cortisol and progesterone (p's<0.001) concentrations. Estradiol concentrations were not different between the sexes (p = 0.24). Pro-inflammatory cytokines were a significant mediator in the relationship between sex and probability of developing nonremitting PTSD (p < 0.05), such that men had higher concentrations of pro-inflammatory cytokines which were associated with lower risk of nonremitting PTSD development. This effect was significantly moderated by estradiol (p < 0.05), as higher estradiol levels in men were associated with higher pro-inflammatory cytokine concentrations and lower risk for developing nonremitting PTSD. The current results suggest that sex differences in the pro-inflammatory cytokine response to trauma exposure partially mediate the probability of developing nonremitting PTSD, and that the protective ability to mount an pro-inflammatory cytokine response in men may depend on higher estradiol levels in the aftermath of trauma exposure.

Utility of Automated Feeding Data to Detect Social Instability in a Captive Breeding Colony of Rhesus Macaques (Macaca mulatta): A Case Study of Intrafamily Aggression.

Some captive breeding colonies of rhesus macaques live in large outdoor multimale, multifemale social groups. These groups are composed of several matrilineal families, governed by a clear female dominance hierarchy. Aggression within the same or between different matrilineal families due to social instability can result in trauma and mortality. Therefore, a primary management goal is to detect emerging social unrest before the onset of significant fighting and wounding. Accordingly, groups are monitored routinely for changes in dominance and alliance relations as well as for increases in trauma frequency and severity. Decreased food intake is a normal physiologic response to acute stress; therefore, inappetence in key animals or groups of monkeys might be used as an indicator of increased social stress and emerging instability. An incident of intrafamily aggression occurred recently in a breeding group at our facility and resulted in considerable fighting. Because this compound was equipped with an automated feeding system that tracks the caloric intake of individual animals, we retrospectively analyzed feeding data to determine whether significant reduction in caloric consumption occurred prior to the onset of aggression, compared with baseline values. Neither the entire group nor individual families showed any significant differences in total caloric intake between baseline and previous 24 h values; however, the affected family exhibited a 20% reduction in total caloric during the 24 h prior to the aggression. Most notably, the deposed subfamily showed a marked 58% reduction in caloric intake during the prior 24 h, whereas remaining subfamilies showed no significant changes in intake. High-ranking animals of the group, including the α female, ß female, and α male, similarly exhibited marked decreases in caloric intake during that period. These findings indicate that automated feeders can assist management staff with monitoring social stability in breeding colonies of rhesus macaque.

Effect of Chronic Social Stress on Prenatal Transfer of Antitetanus Immunity in Captive Breeding Rhesus Macaques (Macaca mulatta).

Because tetanus can cause significant morbidity and mortality in NHP, colonywide vaccination with tetanus toxoid is recommended for outdoor breeding colonies of rhesus macaques, with primary immunizations commonly given to infants at 6 mo of age followed by booster vaccines every 10 y. Maternal antibodies are thought to offer protective immunity to infants younger than 6 mo. However, historical colony data from the Yerkes National Primate Research Center show a higher incidence of tetanus among infants (≤ 6 mo old) born to subordinate dams. Whether this higher incidence of infantile tetanus is due to a higher incidence of trauma among subordinate animals or is a stress-induced impairment of maternal antibody protection is unknown. Studies in other NHP species suggest that chronic exposure to social stressors interferes with the receptor-mediated transplacental transfer of IgG. Therefore, the primary aim of this study was to determine whether chronic stress associated with social subordination impairs prenatal transfer of antitetanus immunity in breeding female rhesus macaques. Subjects included 26 high- and 26 low-ranking adult female rhesus macaques that were nearly 5 or 10 y after their initial immunization and their nonimmunized infants. We hypothesized that infants born to subordinate dams that were nearly 10 y after immunization would have the lowest infant-to-dam antibody ratios and thus would be at greatest risk for infection. Results revealed no significant intergroup differences in infant antitetanus IgG levels. However, infant-to-dam IgG ratios against tetanus were significantly lower among subordinate animals compared with dominant macaques, after accounting for the number of years since the dam's initial vaccination. In addition, higher maternal hair cortisol levels predicted lower infantto-dam tetanus toxoid IgG ratios. Together, these findings suggest that chronic social stress in female rhesus macaques may hamper the prenatal transfer of antitetanus immunity to offspring.

Accuracy of Human and Veterinary Point-of-Care Glucometers for Use in Rhesus Macaques (Macaca mulatta), Sooty Mangabeys (Cercocebus atys), and Chimpanzees (Pan troglodytes).

Handheld, point-of-care glucometers are commonly used in NHP for clinical and research purposes, but whether these devices are appropriate for use in NHP is unknown. Other animal studies indicate that glucometers should be species-specific, given differences in glucose distribution between RBC and plasma; in addition, Hct and sampling site (venous compared with capillary) influence glucometer readings. Therefore, we compared the accuracy of 2 human and 2 veterinary glucometers at various Hct ranges in rhesus macaques (Macaca mulatta), sooty mangabeys (Cercocebus atys), and chimpanzees (Pan troglodytes) with that of standard laboratory glucose analysis. Subsequent analyses assessed the effect of hypoglycemia, hyperglycemia, and sampling site on glucometer accuracy. The veterinary glucometers overestimated blood glucose (BG) values in all species by 26 to 75 mg/dL. The mean difference between the human glucometers and the laboratory analyzer was 7 mg/dL or less in all species. The human glucometers overestimated BG in hypoglycemic mangabeys by 4 mg/dL and underestimated BG in hyperglycemic mangabeys by 11 mg/dL; similar patterns occurred in rhesus macaques. Hct did not affect glucometer accuracy, but all samples were within the range at which glucometers generally are accurate in humans. BG values were significantly lower in venous than capillary samples. The current findings show that veterinary glucometers intended for companion-animal species are inappropriate for use in the studied NHP species, whereas the human glucometers showed clinically acceptable accuracy in all 3 species. Finally, potential differences between venous and capillary BG values should be considered when comparing and evaluating results.

Long-term effects of castration on the skeleton of male rhesus monkeys (Macaca mulatta).

While osteopenia (OPE) and osteoporosis (OPO) have been studied in various species of aging nonhuman primates and extensively in ovariectomized rhesus and cynomolgus macaques, there is virtually no information on the effects of castration on the skeleton of male nonhuman primates. Most information on castrated male primates comes from a few studies on the skeletons of eunuchs. This report used a subset of the Caribbean Primate Research Center's (CPRC) Cayo Santiago (CS) rhesus macaque skeletal collection to qualitatively and quantitatively compare the bone mineral density (BMD) of castrated and age-matched intact males and, thereby, determine the long-term effects of castration (orchidectomy) on bone. Lumbar vertebrae, femora, and crania were evaluated using dual-energy X-ray absorptiometry (DEXA or DXA) and digital radiography augmented, when fresh tissues were available, with autoradiography and histology. Results confirmed physical examinations of long bones that castration causes changes in the skeleton of male rhesus macaques similar to those found in eunuchs, including OPE and OPO of the vertebrae and femora, thinning of the skull, and vertebral fractures and kyphosis of the spine more severe than that caused by normal aging alone. Also like eunuchs, some castrated CS male rhesus monkeys had a longer life span than intact males or females. Based on these results and the effects of castration on other tissues and organs of eunuchs, on behavior, hormone profiles and possibly on cognition and visual perception of human and nonhuman primates, and other mammals, castrated male rhesus macaques should be used with caution for laboratory studies and should be considered a separate category from intact males. Despite these caveats, the castrated male rhesus macaque should make an excellent animal model in which to test hormone replacement therapies for boys and men orchidectomized for testicular and prostate cancer.

Massive occlusive thrombosis of the pulmonary artery in pigtailed macaques chronically infected with R5-tropic simian-human immunodeficiency virus.

BACKGROUND: Pulmonary arterial hypertension (PAH) has been identified as a serious complication of HIV infection. METHODS AND RESULTS: Here, we report sudden death in two pigtailed macaques (Macaca nemestrina) chronically infected (~1-2 years post-infection) with an R5 SHIV strain. At necropsy, total occlusion of the pulmonary artery by a large fibrin thrombus was present in both animals. CONCLUSION: This report describes pulmonary vascular lesions similar to PAH in R5 SHIV-infected pigtail macaques.

Understanding the control of ingestive behavior in primates.

This article is part of a Special Issue "Energy Balance". Ingestive behavior in free-ranging populations of nonhuman primates is influenced by resource availability and social group organization and provides valuable insight on the evolution of ecologically adaptive behaviors and physiological systems. As captive populations were established, questions regarding proximate mechanisms that regulate food intake in these animals could be more easily addressed. The availability of these captive populations has led to the use of selected species to understand appetite control or metabolic physiology in humans. Recognizing the difficulty of quantitating food intake in free-ranging groups, the use of captive, singly-housed animals provided a distinct advantage though, at the same time, produced a different social ecology from the animals' natural habitat. However, the recent application of novel technologies to quantitate caloric intake and energy expenditure in free-feeding, socially housed monkeys permits prospective studies that can accurately define how food intake changes in response to any number of interventions in the context of a social environment. This review provides an overview of studies examining food intake using captive nonhuman primates organized into three areas: a) neurochemical regulation of food intake in nonhuman primates; b) whether exposure to specific diets during key developmental periods programs differences in diet preferences or changes the expression of feeding related neuropeptides; and c) how psychosocial factors influence appetite regulation. Because feeding patterns are driven by more than just satiety and orexigenic signals, appreciating how the social context influences pattern of feeding in nonhuman primates may be quite informative for understanding the biological complexity of feeding in humans.

Effects of bazedoxifene, conjugated equine estrogens, and a tissue-selective estrogen complex containing both bazedoxifene and conjugated equine estrogens on cerebral artery atherosclerosis in postmenopausal monkeys.

OBJECTIVE: This study aims to evaluate the effects of a new selective estrogen receptor modulator (bazedoxifene acetate [BZA]) and a tissue-specific estrogen complex (BZA combined with conjugated equine estrogens [CEE]) on the extent and severity of cerebral artery atherosclerosis. METHODS: Ninety-eight surgically postmenopausal monkeys (Macaca fascicularis) were fed a moderately atherogenic diet and randomized to receive no treatment or women's equivalent doses of BZA (20 mg/d), CEE (0.45 mg/d), or BZA + CEE. After an experimental period of 20 months (approximately equivalent to 5 years of participant experience), the extent and severity of atherosclerosis in the common carotid artery, carotid bifurcation, internal carotid artery, and basilar artery were determined. Lesion severity was determined using the American Heart Association grading system (grades 0-V). RESULTS: BZA had no consistent adverse effects on the extent and severity of atherosclerosis in the cerebral arteries and did not attenuate the beneficial effects of CEE on the severity of common carotid artery atherosclerosis. Although CEE had only modest beneficial effects on the extent of carotid bifurcation atherosclerosis, the severity of lesions and the number of affected cases in the common carotid artery were reduced with CEE treatment. As reported previously, plasma lipid profiles did not differ among the treatment groups. CONCLUSIONS: In this long-term (equivalent to 5 human patient-years) nonhuman primate trial, BZA shows no consistent adverse effect on cerebral artery atherosclerosis and does not attenuate the modest beneficial effect of CEE on the common carotid artery. Furthermore, CEE inhibits the development of complicated plaques in the common carotid artery.

Endometrial profile of bazedoxifene acetate alone and in combination with conjugated equine estrogens in a primate model.

OBJECTIVE: Concerns of breast cancer risk in postmenopausal women taking combined estrogen + progestin therapy have generated interest in the use of selective estrogen receptor modulators (SERMs) as potential progestin alternatives. Endometrial proliferation and cancer risk are major concerns, however, for estrogens and certain types of SERMs when given alone. The primary aim of this study was to evaluate the endometrial profile of bazedoxifene acetate (BZA), a third-generation SERM, alone and in combination with conjugated equine estrogens (CEE) in a postmenopausal primate model. METHODS: Ninety-eight ovariectomized cynomolgus monkeys (Macaca fascicularis) were randomized to receive no hormone treatment (controls), BZA 20 mg, CEE 0.45 mg, or the combination of BZA 20 mg + CEE 0.45 mg once daily for 20 months in a parallel-arm study design. The primary outcome measure was endometrial epithelial proliferation. RESULTS: BZA + CEE and BZA treatment resulted in significantly less endometrial epithelial area and Ki67 expression compared with CEE (P < 0.001 for all). The prevalence of endometrial hyperplasia and other estrogen-induced morphologic changes in the BZA + CEE and BZA groups was not significantly different from controls. The addition of BZA to CEE completely inhibited the expression of estrogen receptor-α-regulated genes (TFF1 and PGR), whereas BZA alone had no effect. BZA + CEE and BZA treatment also resulted in lower estrogen receptor-α protein expression in the endometrium compared with the control and CEE groups (P < 0.05 for all). CONCLUSIONS: BZA given at a clinically relevant dose inhibits estrogen effects on the endometrium and lacks uterotropic effects when given alone.

Effects of bazedoxifene alone and with conjugated equine estrogens on coronary and peripheral artery atherosclerosis in postmenopausal monkeys.

OBJECTIVE: The objectives of this study were to evaluate the effects of bazedoxifene acetate (BZA), a new selective estrogen receptor modulator, on coronary and peripheral artery atheroscleroses and to determine if it would antagonize the atheroprotective effects of conjugated equine estrogens (CEE) on a monkey model. METHODS: Ninety-eight surgically postmenopausal monkeys (Macaca fascicularis) were fed a moderately atherogenic diet and randomized to receive no treatment or women's equivalent doses of BZA (20 mg/d), CEE (0.45 mg/d), or BZA + CEE. The experimental period lasted for 20 months (equivalent to approximately 5 y in humans) during which interim measures of cardiovascular risk factors were made. At the end of the experimental period, the extent and severity of coronary and iliac artery atheroscleroses were quantified. RESULTS: Body weight, adiposity, fasting glucose concentrations, and plasma lipid profiles were not different among treatment conditions. BZA had no adverse effects on the extent or severity of coronary or common iliac artery atherosclerosis when compared with no treatment. CEE, administered soon after inducing menopause, had robust atheroprotective effects on both the extent and the severity of iliac and coronary artery atheroscleroses. The addition of BZA to CEE treatment antagonized the atheroprotective effects of CEE. CONCLUSIONS: In this nonhuman primate trial, treatment with BZA alone, CEE alone, and combined BZA and CEE does not have significant effects on plasma lipid profiles. CEE markedly inhibits the progression and complications of both coronary and iliac artery atheroscleroses. BZA has no adverse effects on atherosclerosis but attenuates the atheroprotective effects of CEE.

Effects of bazedoxifene acetate with and without conjugated equine estrogens on the breast of postmenopausal monkeys.

OBJECTIVE: Concerns about increased breast cancer risk with estrogen and progestin therapy have led to an increased interest in progestin alternatives. The main objective of this study was to determine if bazedoxifene acetate (BZA), a new selective estrogen receptor modulator, will antagonize the proliferative and transcriptional effects of conjugated equine estrogens (CEE) in the breast. METHODS: As part of a 20-month preclinical trial, 95 ovariectomized cynomolgus macaques (Macaca fascicularis) were randomized to receive no treatment or treatment with BZA (20 mg/d), CEE (0.45 mg/d), or BZA and CEE in combination (women's daily equivalent doses). The data presented here include breast effects after 6 months of treatment. Endpoints included histomorphometry, histopathological evaluations, gene microarray assays, polymerase chain reaction quantification of specific estrogen receptor α (ER-α) activity markers, and immunohistochemical detection of sex steroid receptors, and the proliferation marker Ki67. RESULTS: BZA + CEE and BZA resulted in significantly less total epithelial density, lobular enlargement, and Ki67 immunolabeling in the terminal ducts compared with CEE alone (P < 0.05 for all). The addition of BZA to CEE antagonized the expression of ER-α-regulated genes such as GREB1 and TFF1 (P < 0.01 for both), whereas BZA alone had minimal effects on ER-α-mediated transcriptional activity. BZA and BZA + CEE did not significantly up-regulate genes related to cell cycle progression and proliferation. BZA with and without CEE also resulted in less lobular and terminal duct ER-α immunolabeling compared with control and CEE (P < 0.0001 for all). CONCLUSIONS: These findings demonstrate that BZA given at a clinically relevant dose is an estrogen antagonist in the breast, supporting the idea that CEE + BZA may provide a lower breast cancer risk profile compared with traditional estrogen + progestin therapies.

Endocrine profile of an ovariectomized cynomolgus monkey (Macaca fascicularis) with a supernumerary ovary.

For 21 mo after a bilateral ovariectomy, a 19-y-old ovariectomized cynomolgus macaque (Macaca fascicularis) continued to have menstrual cycles and measurable premenopausal estradiol and progesterone concentrations. Among these 10 menstrual cycles, 5 cycles were normal in duration and 5 were prolonged. At necropsy, a firm nodule was identified in the omental fat, and histologic evaluation confirmed the presence of ovarian tissue containing various stages of atretic follicles, a regressing corpora lutea, and a degenerating antral follicle. The endometrium and vaginal epithelium were atrophic. The occurrence of ectopic ovarian tissue in any form and location is a rare gynecologic condition in both women and nonhuman primates. Previously reported cases in nonhuman primates have been incidental findings at necropsy; therefore, the steroidogenic capacity and endocrine-related sequelae of such ovarian tissue in any nonhuman primate species is unknown. Based on structure, location, and relationship to normally situated ovaries, the ovarian tissue in this case was classified as a supernumerary ovary. To our knowledge, this is the first case report of a supernumerary ovary in a cynomolgus macaque. This report demonstrates that supernumerary ovaries in nonhuman primates can be biologically active for many years beyond sexual maturity and should be considered as a possible cause for vaginal bleeding and elevated ovarian hormone concentrations after ovariectomy.

Reproductive aging and risk for chronic disease: Insights from studies of nonhuman primates.

Reproductive aging and ovarian senescence have considerable public health relevance because they are associated with increased risk for coronary heart disease (CHD), osteoporosis and other degenerative conditions including cognitive decline and potentially the metabolic syndrome. It has been suggested that the hormonal dysregulation that occurs during the perimenopausal transition may play a role in the initiation of pathobiological changes (e.g., adverse lipid profiles, atherosclerotic plaques) that will increase risk for chronic disease (e.g., CHD) during the postmenopausal years. Moreover, these early changes are suspected to establish a trajectory of disease progression that may be difficult to alter if interventions are not begun until after menopause. Even a slight increase in the rate of disease progression during the pre- or perimenopausal years could have substantial consequences for health and quality of life over the postmenopausal lifespan. Thus, the years leading up to menopause may offer a "critical window" for interventions aimed at reducing the postmenopausal disease burden. The relationship between perimenopausal hormonal dysregulation and the risk for chronic disease is poorly understood due, in large part, to the lack of appropriate animal models of the perimenopausal transition and natural menopause. In this review we assesses studies of nonhuman primates (NHPs) evaluated in various reproductive stages (naturally pre-, peri- and postmenopausal, surgically menopausal) and their contribution to our understanding about risk factors for chronic disease. Finally, because large numbers of naturally perimenopausal and menopausal NHPs are not available for research at present, experimental approaches that have the potential to hasten the onset of the perimenopausal transition will be described.

Experimental induction of reduced ovarian reserve in a nonhuman primate model (Macaca fascicularis).

Chronic diseases including coronary heart disease and osteoporosis represent a substantial health burden to postmenopausal women, yet the initiation of these conditions and their relationships with reproductive aging remain poorly understood. This situation is due, in part, to the lack of animal models reflecting ovarian and hormonal characteristics of peri- and postmenopausal women. Ovaries of women approaching menopause are nearly depleted of primordial follicles but retain a pool of larger developing follicles and androgen-producing stroma, a condition known as reduced ovarian reserve (ROR). The long-term goal of the research presented here was to create a monkey model of reproductive aging, beginning with ROR and progressing to perimenopause and finally postmenopause. Here we sought to develop a method to reduce primordial follicles in cynomolgus monkeys (Macaca fascicularis) and document hormonal changes associated with follicle reduction or ROR. At 30 d after surgical placement of a biodegradable fiber containing approximately 200 mg of 4-vinlycyclohexene diepoxide (VCD) next to one ovary in each of 8 monkeys, primordial follicles were reduced by approximately 70%, with a corresponding decrease (83%) in antimüllerian hormone (AMH, a serum marker of ovarian follicle numbers). At 4 mo after VCD-treatment of both ovaries in 29 monkeys (approximately 200 mg VCD per ovary), AMH was reduced 56% from baseline, testosterone was unchanged, and follicular phase estradiol was slightly increased. These data indicate that VCD treatment markedly reduced primordial follicles while preserving larger estradiol- and testosterone-producing follicles and ovarian stroma, a condition that mimics ROR in women.