Age-related nomograms of serum anti-Mullerian hormone levels in female monkeys: Comparison of rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) monkeys

Do the blood anti-Müllerian hormone concentrations in young females correlate with the ovarian follicular population later in life in water buffalo?

In this longitudinal study, the anti-Müllerian hormone (AMH) levels in blood were determined in 32 Murrah buffalo females at 8, 10, 12, 16 and 19 months of age when females were synchronized and the antral follicular population (AFP) was estimated. Correlations of AFP to the AMH level at 19 months of age and retrospectively to younger ages were investigated. Then females were split into high and low AFP, and their AMH levels were compared for all ages and tested as predictors of AFP categories. The highest AMH level (p < .05) was detected at 8 months, reducing but not differing (p > .05) at 10, 12 and 16 months then reducing again (p < .05) at 19 months of age. The mean AFP was 17.6 ± 6.3 follicles, and it was positively correlated with AMH in all ages tested. High AFP females had approximately two times more antral follicles than low AFP (p < .05) and their AMH levels were higher (p < .01) than in low AFP ones in all ages. Only at 8 months, AMH levels can be used to precociously detect high AFP heifers (a cut-off point of 464.7 pg/mL; p < .05), while low AFP heifers could be detected by AMH measurements at 8, 10, 12 and 16 months of age (p < .05). We conclude that AMH of buffalo calves correlates with AFP of heifers later in life and depending on the age, its levels could be used to identify future females with low or high AFP.

Cellular and molecular mechanisms of highly active mesenchymal stem cells in the treatment of senescence of rhesus monkey ovary

BACKGROUND

Recent studies have shown that umbilical cord mesenchymal stem cells have an anti-aging effect in ovaries, but the cellular and molecular mechanisms of HA-MSC ovarian anti-aging remain to be studied. Therefore, we conducted a 10X Genomics single-nucleus transcriptome sequencing experiment on the ovaries of macaque monkeys after HA-MSC treatment.

METHODS

The results of cell subgroup classification were visualized by 10X Genomics single nuclear transcriptome sequencing. The aging model of hGCs was established, and the migration ability of the cells was determined after coculture of HA-MSCs and aging hGCs. The genes screened by single nuclear transcriptional sequencing were verified in vitro by qPCR.

RESULTS

Compared with the aging model group, the number of cell receptor pairs in each subgroup of the HA-MSC-treated group increased overall. Treatment with 200 μmol/L H2O2 for 48 h was used as the optimum condition for the induction of hGC senescence. After coculture of noncontact HA-MSCs with senescent hGCs, it was found that HA-MSCs can reverse the cell structure, proliferation ability, senescence condition, expression level of senescence-related genes, and expression level of key genes regulating the senescence pathway in normal hGCs.

CONCLUSIONS

HA-MSC therapy can improve the tissue structure and secretion function of the ovary through multiple cellular and molecular mechanisms to resist ovarian aging. In vitro validation experiments further supported the results of single-cell sequencing, which provides evidence supporting a new option for stem cell treatment of ovarian senescence.

Effect of age and sex on hematological and biochemical parameters in Chinese rhesus monkeys (Macaca mulatta) anesthetized with ketamine

OBJECTIVE

Rhesus monkeys are increasingly used in biomedical research, which makes their hematological and biochemical parameters increasingly important in preclinical research. Since age and sex can influence blood parameters, establishing reference intervals for such parameters based on age and sex becomes along with identifying the effect of age and sex on those parameters.

METHODS

A total of 1385 healthy Chinese rhesus monkeys (548 males and 837 females) anesthetized with ketamine were selected and segregated by age (six groups) and sex. A total of 21 hematological and 26 biochemical parameters were measured, and the effects of age and sex were analyzed.

RESULTS

We established baseline indices for hematological and biochemical parameters based on age and sex, separately, and observed significant impacts of age, sex, and age-sex interactions on blood parameters. Among different age groups, significant differences were found in WBC, NEUT%, LYM%, EO%, LYM#, EO#, MCV, RDW-CV, PLT, MPV, PDW, PCT, TP, Alb, GLB, A/G, ALT, AST, ALP, TBIL, GGT, BUN, Cre, GLU, CK, TRIG, LDL, HCY, IL-6 FOL, Vit B12, VIT D-T, PTH, and AMH. Additionally, significant differences were observed in RBC, HGB, HCT, MPV, Alb, BUN, Cre, GLU, CHOL, TRIG, HDL, LDL, HCY, and VIT D-T between the two sexes. An age-sex interaction exerted a significant effect on WBC, NEUT#, MCV, MCHC, PDW, GLB, ALP, Cre, CHOL, TRIG, HDL, LDL, HCY, IL-6, Vit B12, VIT D-T. However, neither age, sex, and age-sex interactions exerted significant effects on MO%, MOMO#, MCH, RDW-SD, CRP, and CT.

CONCLUSION

Our study investigated the blood parameters of rhesus monkeys to provide a reference basis for rhesus monkey-related scientific experimental research.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

The observed pattern and hidden process of female reproductive trajectories across the life span in a non-human primate

Age-specific fertility trajectories are fundamental to understanding population structure and the evolutionary ecology of diverse life histories. However, characterizing reproductive ageing has been difficult with cross-sectional data, where senescence especially late in life can be confounded by selective disappearance. Addressing such challenge requires longitudinal data tracking the reproductive life span of known individuals, but such data are rare, especially for very long-lived species such as primates. We analyse the entire life span trajectory of annual fertility, from reproductive maturity to death, for 673 free-ranging female rhesus macaques, Macaca mulatta, on Cayo Santiago, Puerto Rico. Using generalized linear mixed-effects models (GLMMs), we first tested if time to death explains the ageing pattern independently of and additionally to chronological age, and if so, whether there is interaction between them. While GLMM captures the patterns in the data well, it is not a generative model. For example, given the GLMM and an individual's reproductive trajectory up to a given age, we cannot directly predict the probability of reproduction or death in the next year. For this reason, we further fitted a hidden Markov chain model (HMM) which allows just such a prediction, and additionally helps infer the process underlying the observed trajectory. We show that, after accounting for individual differences in fertility, reproductive ageing exhibits both age-dependent decline and also an abrupt terminal decline independently of age at death. We infer from the HMM that the underlying process of reproductive trajectory is where individuals cycle between reproductive bouts until they enter an irreversible frail condition that constrains fertility. The findings provide valuable insights into the longitudinal progression of reproductive trajectories in primates, by revealing both age-dependent and age-independent patterns and processes of ageing, and contribute to a growing body of literature on reproductive ageing and senescence across animal taxa.

The effects of delta-9-tetrahydrocannabinol exposure on female menstrual cyclicity and reproductive health in rhesus macaques

OBJECTIVE

To determine the dose-dependent effect of contemporary marijuana exposure on female menstrual cyclicity and reproductive endocrine physiology in a nonhuman primate model.

DESIGN

Research animal study.

SETTING

Research institute environment.

ANIMALS

Adult female rhesus macaques (6-12 years of age; n = 8).

INTERVENTIONS

Daily delta-9-tetrahydrocannabinol (THC) edible at medically and recreationally relevant contemporary doses.

MAIN OUTCOME MEASURES

Menstrual cycle length (MCL), anti-Müllerian hormone, prolactin, basal follicle-stimulating hormone (FSH), estradiol (E2) and progesterone, luteinizing hormone (LH), and thyroid-stimulating hormone.

RESULTS

The average before THC weight was 6.9 kg (standard deviation, 0.8), and at the highest THC dosing, the average weight was 7.2 kg (standard deviation, 0.8). With increasing THC dosing, MCL and FSH concentrations increased, while basal E2 concentration was stable. The average MCL concentration increased 4.0 days for each mg/7 kg/day of THC (95% CI, 1.4-6.6 days). Follicle-stimulating hormone concentration increased significantly with increasing THC dose, 0.34 ng/mL for each mg/7 kg/day of THC (95% CI, 0.14-0.57 ng/mL). No significant trends were observed between THC dosing and average basal progesterone, anti-Müllerian hormone, prolactin, LH, or thyroid-stimulating hormone concentrations.

CONCLUSIONS

In rhesus macaques, a dose response toward increased MCL and basal FSH concentrations but plateau of basal E2 and LH concentrations was observed with increasing THC dosing, suggesting ovulatory dysfunction. Further studies are needed to determine the effects of a longer duration of exposure and whether the significant increase in MCL and FSH concentrations results in reduced fecundity.

Lack of effect of short-term DHEA supplementation on the perimenopausal ovary†

Dehydroepiandrosterone (DHEA) hormonal supplementation can improve oocyte quality in women with diminished ovarian function. However, it is unclear whether DHEA supplementation can also enhance ovarian function during the perimenopause (i.e., when the number of follicles in the ovary has undergone a marked reduction). To address this question, we examined the impact of 2.5-months of daily 5-mg oral DHEA supplementation on the number of ovarian follicles and the concentration of anti-Müllerian hormone (AMH) in perimenopausal rhesus macaques. Like women, these long-lived nonhuman primates have ~ 28-day menstrual cycles and eventually undergo menopause. They also show similar age-related neuroendocrine changes, including a marked decrease in circulating concentrations of DHEA and DHEA sulfate (DHEAS). Our experimental design involved the following three groups of animals (N = 6 per group): Young adult (mean age = 11.6 years), Old control (mean age = 23.1 years), and Old DHEA-treated (mean age = 23.5 years). Histological examination of the ovaries revealed a significant age-related decrease in the mean number of primordial follicles despite DHEA supplementation. Moreover, AMH concentrations within the ovaries and circulation, assessed by Western analysis and ELISA, respectively, showed significant age-related decreases that were not attenuated by DHEA supplementation. Taken together, these results fail to show a clear effect of short-term physiological DHEA supplementation on the perimenopausal ovary. However, they do not exclude the possibility that alternative DHEA supplementation paradigms (e.g., involving an earlier start date, longer duration and using pharmacological doses) may extend reproductive potential during aging.

Age-related changes in microbial composition and function in cynomolgus macaques

Age can significantly affect human physiology and disease risk. Recent studies have shown that age may affect the composition and function of the gut microbiota, but the underlying mechanisms remain largely unknown. Non-human primates are an ideal model for uncovering how age shapes the gut microbiota, as their microbial composition is highly similar to that of humans and is not easily affected by confounding factors. Here, using the 16S rRNA and metagenomic sequencing methods, we characterized the microbial phenotypes of 16 female cynomolgus macaques from three age groups (young, adult and old). Our findings revealed significant differences in microbial composition among the three groups. With increased age, the relative abundances of Veillonellaceae, Coriobacteriaceae and Succinivibrionaceae were significantly increased, Ruminococcaceae and Rikenellaceae were significantly decreased at the family level. Functional enrichment showed that genes that differed among the three groups were mainly involved in arginine biosynthesis, purine metabolism and microbial polysaccharides metabolism. Moreover, CAZymes corresponding to polysaccharide degrading activities were also observed among the three groups. In conclusion, we characterized the composition and function of the gut microbiota at different ages, and our findings provide a new entry point for understanding the effects of age on the human body.