Early Life Environment Research Articles

Immune-microbe interactions early in life: A determinant of health and disease long term.

Research on newborn immunity has revealed the importance of cell ontogeny, feto-maternal tolerance, and the transfer of maternal antibodies. Less is known about postnatal adaptation to environmental exposures. The microbiome and its importance for health have been extensively studied, but it remains unclear how mutually beneficial relationships between commensal microbes and human cells first arise and are maintained throughout life. Such immune-microbe mutualism, and perturbations thereof, is most likely a root cause of increasing incidences of immune-mediated disorders such as allergies and autoimmunity across many industrialized nations during the past century. In this Review, I discuss our current understanding of immune development and propose that mismatches among ancestral, early-life, and adult environments can explain perturbations to immune-microbe interactions, immune dysregulation, and increased risks of immune-mediated diseases.

Upper arm length and knee height are associated with diabetes in the middle-aged and elderly: evidence from the China Health and Retirement Longitudinal Study.

To determine if limb lengths, as markers of early life environment, are associated with the risk of diabetes in China. We performed a cohort analysis using data from the China Health and Retirement Longitudinal Study (CHARLS), and multivariable-adjusted Cox proportional hazard regression models were used to examine the associations between baseline limb lengths and subsequent risk of diabetes. The CHARLS, 2011-2018. The study confined the eligible subject to 10 711 adults aged over 45 years from the CHARLS. During a mean follow-up period of 6·13 years, 1358 cases of incident diabetes were detected. When controlling for potential covariates, upper arm length was inversely related to diabetes (hazard ratio (HR) 0·95, 95 % CI (0·91, 0·99), P = 0·028), and for every 1-cm difference in knee height, the risk of diabetes decreased by about 4 % (HR 0·96, 95 % CI (0·93, 0·99), P = 0·023). The association between upper arm length and diabetes was only significant among females while the association between knee height and diabetes was only significant among males. In analyses stratified by BMI, significant associations between upper arm length/knee height and diabetes only existed among those who were underweight (HR 0·91, 95 % CI (0·83, 1·00), P = 0·049, HR 0·92, 95 % CI (0·86, 0·99), P = 0·031). Inverse associations were observed between upper arm length, knee height and the risk for diabetes development in a large Asian population, suggesting early life environment, especially infant nutritional status, may play an important role in the determination of future diabetes risk.

Utility of preclinical models of altered maternal nutrition to support the developmental origins of health and disease hypothesis.

A clear link has been established between alterations in the early life environment and the risk for developing a range of cardiometabolic diseases in later life, a process preferentially termed developmental programming. In particular, alterations in the maternal nutritional environment have been associated with a range of adverse health outcomes in offspring across the lifecourse; effects that can be passed on to future generations. Following from the early epidemiological observations that provided the basis for the developmental origins of health and disease (DOHaD) hypothesis, a range of animal models were developed to examine the impact of early life programming and provide empirical data to support the emerging framework. These models became key tools to aid in our understanding of developmental programming as allowed investigation of potential mechanisms, strategies for intervention and transgenerational effects. The study published by Langley and Evans (Clin. Sci. 1994;86(2):217–222; DOI:10.1042/CS0860217), using a rat model of maternal low protein exposure, was one of the first to highlight the impact of an altered maternal nutritional environment on programming of elevated blood pressure in offspring. This work became a hallmark study in the DOHaD field by demonstrating key proof of principle to support the early epidemiological associations and characterizing a key preclinical model that has contributed greatly to our understanding of mechanisms underpinning developmental programming—particularly in the area of cardiovascular and renal function.

Nutritional and environmental epigenetics effects on human health and diseases

Both industrialized and developing nations see an alarming rise in adult-onset illnesses such as T2D and CVD. According to human and animal research, prenatal and early postnatal circumstances may alter a person's vulnerability to chronic diseases later in life. Epigenetic modulation of gene expression has been proposed as one of the processes through which early life environment impacts future illness risk. It is possible that our understanding of the underlying mechanisms may lead us to design new intervention strategies that can lessen the burden of sickness in later life.

The Effect of Manipulated Prenatal Conditions on Growth, Survival, and Reproduction Throughout the Complete Life Course of a Precocial Bird

The quality of the environment individuals experience during development is commonly regarded as very influential on performance in later life. However, studies that have experimentally manipulated the early-life environment and subsequently measured individual performance in all components of fitness over the complete life course are scarce. In this study, we incubated fertile eggs of Japanese quail (Coturnix japonica) at substandard and standard incubation temperature, and monitored growth, survival, and reproduction throughout the complete life course. While embryonic development was slower and hatching success tended to be lower under substandard incubation temperature, the prenatal treatment had no effect on post-hatching growth, survival to sexual maturity, or age at first reproduction. In adulthood, body mass and investment in individual egg mass peaked at middle age, irrespective of the prenatal treatment. Individual reproduction rate declined soon after its onset, and was higher in females that lived longer. Yet, reproduction, and its senescence, were independent of the prenatal treatment. Similarly, adult survival over the complete lifespan was not affected. Hence, we did not find evidence for effects on performance beyond the developmental period that was manipulated. Our results suggest that effects of unfavorable developmental conditions on individual performance later in life could be negligible in some circumstances.

Variation of cisco egg size among Laurentian Great Lakes populations

Many fish species display inter-population and inter-individual egg size variation. Intra-specific differences in egg size seemingly reflect both energetic experiences of individual spawning fish and long-term population responses to differing ecosystems. Optimal egg size theory implies that selection influences a population’s mean egg size in response to its early-life environment, given the well-established trade-off between egg size and fecundity. Currently, there is strong interest in rehabilitation of Laurentian Great Lakes cisco, Coregonus artedi, which is characterized by inter-population variation of morphological and behavioral traits. However, the extent of cisco egg size variation is under-described. In fall 2018 and 2019, we collected egg samples by stripping ripe females at seven total locations in four Great Lakes. We measured unfertilized egg diameters using imaging software and compared mean egg diameters among locations with and without including maternal total length as a covariate. Lake Michigan females produced the largest eggs overall but were excluded from analyses using the total length covariate because of their significantly larger body sizes. Maternal length had a positive effect on egg size, and when accounting for this effect, females in Lake Huron produced the largest eggs followed by Lake Ontario and Lake Superior. We also found that egg size varied among locations within Lake Superior. These findings aligned with observations of morphological and behavioral differences among populations and suggest that cisco phenotypic variation at a fine spatial scale extends to reproductive biology. Consideration of cisco reproductive traits, such as egg size, may inform restoration strategies, including supplemental stocking.

Strong Parallel Differential Gene Expression Induced by Hatchery Rearing Weakly Associated with Methylation Signals in Adult Coho Salmon (O. kisutch).

Human activities and resource exploitation led to a massive decline of wild salmonid populations, consequently, numerous conservation programs have been developed to supplement wild populations. However, many studies documented reduced fitness of hatchery-born relative to wild fish. Here, by using both RNA sequencing and Whole Genome Bisulfite Sequencing of hatchery and wild-born adult Coho salmon (Oncorhynchus kisutch) originating from two previously studied river systems, we show that early-life hatchery-rearing environment-induced significant and parallel gene expression differentiation is maintained until Coho come back to their natal river for reproduction. A total of 3,643 genes differentially expressed and 859 coexpressed genes were downregulated in parallel in hatchery-born fish from both rivers relative to their wild congeners. Among those genes, 26 displayed a significant relationship between gene expression and the median gene body methylation and 669 single CpGs displayed a significant correlation between methylation level and the associated gene expression. The link between methylation and gene expression was weak suggesting that DNA methylation is not the only player in mediating hatchery-related expression differences. Yet, significant gene expression differentiation was observed despite 18 months spent in a common environment (i.e., the sea). Finally, the differentiation is observed in parallel in two different river systems, highlighting the fact that early-life environment may account for at least some of the reduced fitness of the hatchery salmon in the wild. These results illustrate the relevance and importance of considering both epigenome and transcriptome to evaluate the costs and benefits of large-scale supplementation programs.

Impact of the intrauterine environment on future reproductive and metabolic health

Key content As survival of babies born following high‐risk pregnancies continues to increase globally, understanding the long‐term impacts of suboptimal intrauterine environments on future health becomes increasingly important. The intrauterine environment is a key influence on later metabolic health, particularly the tendency to later‐life obesity and dyslipidaemia. Recent evidence shows that female reproductive function is also highly sensitive to the influence of the early life environment. Various suboptimal intrauterine environments are linked to adverse reproductive and metabolic outcomes, including maternal obesity, low‐protein diets and chronic fetal hypoxia. Learning objectives To know that the prevalence of high‐risk intrauterine environments is increasing in maternity populations because of, for example, increasing rates of maternal obesity. To be aware of the later‐life health implications for the fetus when caring for women with high‐risk pregnancies. To understand that children who are survivors of high‐risk pregnancies are at increased risk of adverse metabolic health outcomes and more work is required to determine optimal follow‐up.

Learning Ability and Hippocampal Transcriptome Responses to Early and Later Life Environmental Complexities in Dual-Purpose Chicks.

Simple SummaryThe hippocampus region of birds is a pivotal area for learning and memory. Early-life conditions can have a long-lasting impact on animals. However, the influence of early-life and later-life environments on animals’ health and welfare has not been well-studied. This study addresses the impact of early-life enrichment and the later environment on the learning ability and hippocampal responses in chicks. We found that the early-life environmental complexity did not prepare better for learning ability in response to life challenges in the future. This study indicates that perches and litter materials, which enriched early-life conditions, were conducive to improved stress responses later in life in terms of neural- and immune-related gene expression and functional pathways. This can be attributed to the “silver spoon” effect. However, the enrichment through litter materials alone in early life does not improve the hippocampal plasticity in later stressed environments. In addition, early-life barren conditions that match later-life conditions have beneficial impacts on neural development, supporting the match and mismatch theory. This study helps us to understand the relationship between early- and later-life environments from the perspective of animal neural- and immune-related development. It also has the potential to guide the treatment of mental problems and personal health in humans based on the interactions between the early-life and later-life environments. In this study, we hypothesized that complex early-life environments enhance the learning ability and the hippocampal plasticity when the individual is faced with future life challenges. Chicks were divided into a barren environment group (BG), a litter materials group (LG), and a perches and litter materials group (PLG) until 31 days of age, and then their learning abilities were tested following further rearing in barren environments for 22 days. In response to the future life challenge, the learning ability showed no differences among the three groups. In the hippocampal KEGG pathways, the LG chicks showed the downregulation of neural-related genes neuronal growth regulator 1 (NEGR1) and neurexins (NRXN1) in the cell adhesion molecules pathway compared to the BG (p < 0.05). Immune-related genes TLR2 in Malaria and Legionellosis and IL-18 and IL18R1 in the TNF signaling pathway were upregulated in the LG compared to in the BG (p < 0.05). Compared to the BG, the PLG displayed upregulated TLR2A in Malaria (p < 0.05). The PLG showed upregulated neural-related gene, i.e., neuronal acetylcholine receptor subunit alpha-7-like (CHRNA8) in the nicotine addiction pathway and secretagogin (SCGN) gene expression, as compared to the LG (p < 0.05). In conclusion, early-life environmental complexities had limited effects on the learning ability in response to a future life challenge. Early-life perches and litter materials can improve neural- and immune-related gene expression and functional pathways in the hippocampus of chicks.

The role of early-life family composition and parental socio-economic status as risk factors for obsessive-compulsive disorder in a Danish national cohort

Research on early-life family environment on obsessive-compulsive disorder (OCD) risk is limited, and sex differences have not been sufficiently studied. We investigated early-life family composition and parental socio-economic status (SES) as OCD risk factors while stratifying for sex in a sample of 1,154,067 individuals from the Danish population (7550 of whom had OCD). Data on early-life family composition (birth order, number of siblings, number of parents in household at proband age 6), parental SES at age 6 (parental income, occupation, and education level), history of parental psychiatric illness, and parental age at birth on OCD risk (i.e., an ICD-10 diagnosis of F42.x) were obtained from Danish population registers. Survival analyses using Cox regression were performed with age as the underlying time variable. Analyses were adjusted for calendar time, and differential effect by sex was tested for exposures. We found that birth order and advanced maternal age were risk factors for OCD in males, and being an only child was associated with increased OCD risk in both sexes. Early childhood SES variables including parental education, occupation, and income were associated with OCD risk, and these effects were more pronounced in females. Significant interaction effects for parental education/occupation and the presence of non-OCD psychiatric diagnoses in the proband also emerged. Our results suggest that early-life SES and family composition may be important risk factors for OCD, and heterogeneity in OCD cases in terms of psychiatric comorbidities, as well as sex differences should be carefully examined in relation to risk factors.

Contextualizing Educational Disparities in Health: Variations by Race/Ethnicity, Nativity, and County-Level Characteristics.

Educational disparities in health are well documented, yet the education-health relationship is inconsistent across racial/ethnic and nativity groups. These inconsistencies may arise from characteristics of the early life environments in which individuals attain their education. We evaluate this possibility by investigating (1) whether educational disparities in cardiometabolic risk vary by race/ethnicity and nativity among Black, Hispanic, and White young adults; (2) the extent to which racial/ethnic-nativity differences in the education-health relationship are contingent on economic, policy, and social characteristics of counties of early life residence; and (3) the county characteristics associated with the best health at higher levels of education for each racial/ethnic-nativity group. Using data from the National Longitudinal Study of Adolescent to Adult Health, we find that Black young adults who achieve high levels of education exhibit worse health across a majority of contexts relative to their White and Hispanic counterparts. Additionally, we observe more favorable health at higher levels of education across almost all contexts for White individuals. For all other racial/ethnic-nativity groups, the relationship between education and health depends on the characteristics of the early life counties of residence. Findings highlight place-based factors that may contribute to the development of racial/ethnic and nativity differences in the education-health relationship among U.S. young adults.

Associations between Early Life Environmental Exposures and Rhinitis Trajectories in an Urban Birth Cohort

Our objective was to identify longitudinal patterns of chronic rhinitis and their associations with early life environmental exposures in an urban birth cohort of high-risk allergic children through 11 years of age.

A lifecourse approach to the relationship between lung function and cognition function in late life: findings from the Mysore studies of Natal effect on Ageing and Health (MYNAH) in South India

Background: Emerging evidence from high income settings indicates that lung function may be an independent determinant of cognitive abilities in late life. Despite a high burden of chronic lung disorders and neurocognitive disorders, there are limited data exploring the relationship between lung and cognitive function in later life in low- and middle-income (LMIC) settings. Methods: Between 2013 and 2016, 721 men and women from the Mysore Birth Records Cohort in South India, aged 55-80 years, were retraced and underwent standardised assessments for sociodemographic characteristics, cardiometabolic risk factors, lung function, cognitive function and mental health. Approximately 20 years earlier, a subset of them had assessments for cardiometabolic risk factors (n=522) and lung function (n=143). Results: Forced Expiratory Volume at one second (FEV1) and six seconds (FEV6) were higher among men than women. Women had higher immediate and delayed recall scores compared to men. Multivariate models indicated that those with lower FEV1 (lts) and FEV1/FEV6 ratio in late life had lower composite cognitive score (SD, standard deviation), independent of growth and environment in early life and childhood, attained education, socioeconomic position, cardiometabolic disorders in mid-and late life and lifestyle factors (0.29 SD per litre 95% confidence interval [CI] (0.10, 0.50) p=0.006 for FEV1 and 1.32 SD (0.20, 2.50) p=0.02 for FEV1/FEV6 ratio). Lung function in midlife was unrelated to cognitive outcomes in late life. Conclusions: Causality cannot be inferred from cross sectional associations. Therefore, causality is best explored in longitudinal studies with serial, but contemporaneous measurements of both lung and cognitive function. Mechanistic studies that examine the role of shared risk factors like environmental pollutants and biomass exposure on this relationship are urgently required in LMICs.

Epigenetic regulation of 5\u03b1 reductase-1 underlies adaptive plasticity of reproductive function and pubertal timing

BackgroundWomen facing increased energetic demands in childhood commonly have altered adult ovarian activity and shorter reproductive lifespan, possibly comprising a strategy to optimize reproductive success. Here, we sought to understand the mechanisms of early-life programming of reproductive function, by integrating analysis of reproductive tissues in an appropriate mouse model with methylation analysis of proxy tissue DNA in a well-characterized population of Bangladeshi migrants in the UK. Bangladeshi women whose childhood was in Bangladesh were found to have later pubertal onset and lower age-matched ovarian reserve than Bangladeshi women who grew-up in England. Subsequently, we aimed to explore the potential relevance to the altered reproductive phenotype of one of the genes that emerged from the screens.ResultsOf the genes associated with differential methylation in the Bangladeshi women whose childhood was in Bangladesh as compared to Bangladeshi women who grew up in the UK, 13 correlated with altered expression of the orthologous gene in the mouse model ovaries. These mice had delayed pubertal onset and a smaller ovarian reserve compared to controls. The most relevant of these genes for reproductive function appeared to be SRD5A1, which encodes the steroidogenic enzyme 5α reductase-1. SRD5A1 was more methylated at the same transcriptional enhancer in mice ovaries as in the women’s buccal DNA, and its expression was lower in the hypothalamus of the mice as well, suggesting a possible role in the central control of reproduction. The expression of Kiss1 and Gnrh was also lower in these mice compared to controls, and inhibition of 5α reductase-1 reduced Kiss1 and Gnrh mRNA levels and blocked GnRH release in GnRH neuronal cell cultures. Crucially, we show that inhibition of this enzyme in female mice in vivo delayed pubertal onset.ConclusionsSRD5A1/5α reductase-1 responds epigenetically to the environment and its downregulation appears to alter the reproductive phenotype. These findings help to explain diversity in reproductive characteristics and how they are shaped by early-life environment and reveal novel pathways that might be targeted to mitigate health issues caused by life-history trade-offs.

Effects of economic uncertainty and socioeconomic status on reproductive timing: A life history approach

Why do some people have children earlier compared to others who delay reproduction? Drawing from an evolutionary, life history theory perspective, we posited that reproductive timing could be influenced by economic uncertainty and childhood socioeconomic status (SES). For individuals lower in childhood SES, economic uncertainty influenced the desire to reproduce earlier compared to individuals higher in childhood SES. Furthermore, the decision regarding reproductive timing was influenced by tradeoffs between earlier reproduction or furthering one's education or career. Overall, economic uncertainty appears to shift individuals into different life history strategies as a function of childhood SES, suggesting how ecological factors and early life environment can influence fertility-related decisions at the individual level and may contribute to the highly variable fertility patterns observed across countries.

Association of Early-Life Family and Nieghborhood Circumstances With Depressive Symptoms in Chinese Older Adults

A growing body of literature suggests that early life circumstances can influence mental health throughout the lifespan. However, how these early life circumstances cumulatively contribute to depression in old age is not completely understood. The present study examined the associations of eight factors representing multifaceted early life experience at individual, family, and community levels with depression among community-dwelling older adults. Data were from the China Health and Retirement Longitudinal Study. We included 8,239 community-dwelling individuals who were ≥60 years, completed the life history questionnaire, and had assessment of depression. Chi-square test was used to examine the unadjusted associations between each of the eight early life risk factors and depression. An early life disadvantage index was established using risk factors that were significantly associated with depression. Logistic regression was used to examine the association of each early life risk factor and the index with depression. Of 8,239 individuals included, 2,055 (24.9%) had depression. In bivariate analysis, each of eight early life risk factors was significantly associated with depression. Except for maternal and paternal education, all risk factors persisted to be associated with depression after multivariable adjustment. In the multivariable-adjusted model, a one-point higher in the early life disadvantage index (range: 0-6) was associated with a 45% (95% CI: 37%, 53%) higher odds of depression. There was a strong association between early life environments and depressive symptoms among Chinese community-dwelling older adults. Adverse early life circumstances could contribute cumulatively to depression in old age.

A cross-species assay demonstrates that reward responsiveness is enduringly impacted by adverse, unpredictable early-life experiences.

Exposure to early-life adversity (ELA) is associated with several neuropsychiatric conditions, including major depressive disorder, yet causality is difficult to establish in humans. Recent work in rodents has implicated impaired reward circuit signaling in anhedonic-like behavior after ELA exposure. Anhedonia, the lack of reactivity to previously rewarding stimuli, is a transdiagnostic construct common to mental illnesses associated with ELA. Here, we employed an assay of reward responsiveness validated across species, the Probabilistic Reward Task (PRT). In the PRT, healthy participants reliably develop a response bias toward the more richly rewarded stimulus, whereas participants with anhedonia exhibit a blunted response bias that correlates with current and future anhedonia. In a well-established model of ELA that generates a stressful, chaotic, and unpredictable early-life environment, ELA led to blunted response biases in the PRT in two separate cohorts, recapitulating findings in humans with anhedonia. The same ELA rats had blunted sucrose preference, further supporting their anhedonic-like phenotypes. Probing the aspects of ELA that might provoke these deficits, we quantified the unpredictability of dam/pup interactions using entropy measures and found that the unpredictability of maternal care was significantly higher in the ELA groups in which PRT and sucrose preference reward deficits were present later in life. Taken together, these data position the PRT, established in clinical patient populations, as a potent instrument to assess the impact of ELA on the reward circuit across species. These findings also implicate the unpredictability of maternal signals during early life as an important driver of reward sensitivity deficits.

Age‐0 Silver Carp Otolith Microchemistry and Microstructure Reveal Multiple Early Life Environments and Protracted Spawning in the Upper Mississippi River

AbstractSilver Carp Hypophthalmichthys molitrix are highly mobile and fecund planktivorous cyprinids that have invaded much of the Mississippi River and are known to alter food webs and compete with native planktivores. In 2016, for the first time, an abundance of age‐0 Silver Carp (n = 12,208; 16–231 mm) were captured at many (n = 11) sites upstream of Lock and Dam 19 on the upper Mississippi River. Previous reports were of a few individuals at a few locations; however, effort to capture juveniles of this size was likely less in previous years. Determining the origin, frequency, and timing of the reproductive events that led to this large year‐class is important for determining control strategies. We used otolith microstructure and microchemistry from age‐0 Silver Carp to estimate timing and frequency of spawning and early life environments of these fish. Hatch dates were determined from the lapillus otoliths of 190 age‐0 Silver Carp (16–231 mm), and early life environments were identified from otolith microchemistry for 124 of these fish (64–231 mm). Age‐0 Silver Carp were collected from Pools 18 and 19 during July–October 2016 by using a variety of sampling gears. We identified 10 cohorts with hatch dates ranging from May to August 2016 and with main‐stem Mississippi River (75%) and tributary (23%) early life signatures. Tributary otolith chemistry signatures were present in all cohorts between May and July (n = 8) but were absent from the August cohorts (n = 2). Our results indicate that tributaries and small tributary streams, in addition to the main‐stem river, play an important role in Silver Carp recruitment in areas near the reproductive front, where management actions (e.g., contract removal and deterrents) are often targeted.

Earth Dreams: Reimagining ARPA for Health of People, Places and Planet.

Bold new approaches are urgently needed to overcome global health challenges. The proposed Advanced Research Projects Agency for Health (ARPA-H) is intended to provide rapid health breakthroughs. While new technologies for earlier disease detection and more effective treatment are critical, we urge equal attention be given to the wider (physical, emotional, social, political, and economic) environmental ecosystems driving the non-communicable disease (NCD) crisis in the first place. This requires an integrated, cross-sectoral vision that spans the interwoven connections affecting health across the scales of people, places, and planet. This wider “exposome” perspective considers biopsychosocial factors that promote resilience and reduce vulnerabilities of individuals and communities over time—the many variables driving health disparities. Since life course health is strongly determined by early life environments, early interventions should be prioritized as a matter of effectiveness and social justice. Here, we explore the origins of the Advanced Research Project Agency and point to its potential to build integrated solutions, with wisdom and ethical value systems as a compass. Since the planned ARPA-H is anticipated to spawn international collaborations, the imagined concept is of relevance to a broad audience of researchers. With appropriate input, the quest for health equity through personalized, precision medicine while deconstructing unacceptable structural inequities may be accelerated.

Neonatal Maternal Separation Alters Gelatinase Activity in Mouse Ovarian Preantral Follicles.

ObjectiveThe early life environment is critical for normal growth and development for future reproductive function. This study aims to investigate the effect of neonatal maternal separation (MS) on gelatinase activity of mouse ovarian follicles.Materials and MethodsIn this experimental study, infants from female NMRI mice were randomly allocated into two groups immediately after birth: i. MS isolated from their mothers for 6 hours per day, from postpartum days 2 to 16) and ii. Control (undisturbed during the 16 days). Ovarian tissues were dissected to perform differential counts of the ovarian follicle type by haematoxylin and eosin staining. The isolated follicles were cultured for 12 days. Gelatinase activity and the gene expressions of matrix metalloproteinases, MMP2 and MMP9, and their tissue inhibitors, TIMP1 and TIMP2, were evaluated by zymography and real-time polymerase chain reaction (PCR), respectively. Results Follicle counts at the different developmental stages were significantly different between the control and MS groups. There was a significant decrease in gelatinase activity in the MS group compared to the control group. The MS group showed significantly decreased gene expression levels of MMP2 and MMP9 compared to the control group. In contrast, the gene expression levels of TIMP1 and TIMP2 significantly increased in the MS group compared to the control group. ConclusionMS is a stressor agent that compromises ovarian follicle development, at least via disruption of gelatinase activity and its related gene expressions.