Metabolic programming of ovarian angiogenesis and folliculogenesis by maternal malnutrition during lactation

Proteomic analysis of mouse ovaries during the prepubertal stages

Postnatal folliculogenesis, primordial follicle activation and follicular development at early stage are important for normal ovarian function and fertility, and a comprehensive understanding of this process under physiological condition is necessary. To observe the regulation and mechanism of ovarian follicle development during the prepubertal stages, we collected the mouse ovaries from three time points, including 1 day, 7 days, and 4 weeks after birth. We then performed a proteomic analysis using tandem mass tags (TMT) labeling combined with a two-dimensional liquid chromatography-tandem mass spectrometry (2D LC-MS/MS) technique. A total of 706 proteins were determined to be significant differential abundance (P-SDA). Sixty upregulated proteins and 12 downregulated proteins that were P-SDA and 3 significant KEGG pathways (P < 0.05) were found at 7 days vs. 1 day after birth, while 237 upregulated proteins, 271 downregulated proteins and 42 significant KEGG pathways were found for 4 weeks vs. 7 days after birth. Some vital genes (Figla, Ooep, Padi6, Zp3, Hsd3b1, cyp11a1), key pathways (ECM-receptor interaction, focal adhesion, ovarian steroidogenesis, complement and coagulation cascades, PI3K/Akt/mTOR), and metabolic regulation (energy metabolism, lipid metabolism, metal ion metabolism) were found to be related to the postnatal folliculogenesis, primordial follicle activation and follicular development. Finally, qRT-PCR and western blotting verified some vital genes and further elucidated the developmental process of follicles, and the results may contribute to the understanding of the formation and activation of primordial follicle and follicular development. Significance: This study offers the first proteomic insights into mechanisms of follicle development under physiological condition during the prepubertal stages. By comparing P-SDA of mouse ovaries during various period of age, our data reveals that the regulation of primordial follicle formation and activation is significantly different from that of follicular development. These findings demonstrate that many unique molecular mechanisms underlie ovarian development could be used for ovarian disease research.

Preclinical Models of Altered Early Life Nutrition and Development of Reproductive Disorders in Female Offspring

Early epidemiology studies in humans have and continue to offer valuable insight into the Developmental Origins of Health and Disease (DOHaD) hypothesis, which emphasises the importance of early-life nutritional and environmental changes on the increased risk of metabolic and reproductive disease in later life. Human studies are limited and constrained by a range of factors which do not apply to preclinical research. Animal models therefore offer a unique opportunity to fully investigate the mechanisms associated with developmental programming, helping to elucidate the developmental processes which influence reproductive diseases, and highlight potential biomarkers which can be translated back to the human condition. This review covers the use and limitations of a number of animal models frequently utilised in developmental programming investigations, with an emphasis on dietary manipulations which can lead to reproductive dysfunction in offspring.

The 'Developmental Origins' Hypothesis: relevance to the obstetrician and gynecologist

The recognition of 'fetal origins of adult disease' has placed new responsibilities on the obstetrician, as antenatal care is no longer simply about ensuring good perinatal outcomes, but also needs to plan for optimal long-term health for mother and baby. Recently, it has become clear that the intrauterine environment has a broad and long-lasting impact, influencing fetal and childhood growth and development as well as future cardiovascular health, non-communicable disease risk and fertility. This article looks specifically at the importance of the developmental origins of ovarian reserve and ageing, the role of the placenta and maternal nutrition before and during pregnancy. It also reviews recent insights in developmental medicine of relevance to the obstetrician, and outlines emerging evidence supporting a proactive clinical approach to optimizing periconceptional as well as antenatal care aimed to protect newborns against long-term disease susceptibility.

In Utero Origins of Hypertension: Mechanisms and Targets for Therapy

The developmental origins of health and disease theory is based on evidence that a suboptimal environment during fetal and neonatal development can significantly impact the evolution of adult-onset disease. Abundant evidence exists that a compromised prenatal (and early postnatal) environment leads to an increased risk of hypertension later in life. Hypertension is a silent, chronic, and progressive disease defined by elevated blood pressure (>140/90 mmHg) and is strongly correlated with cardiovascular morbidity/mortality. The pathophysiological mechanisms, however, are complex and poorly understood, and hypertension continues to be one of the most resilient health problems in modern society. Research into the programming of hypertension has proposed pharmacological treatment strategies to reverse and/or prevent disease. In addition, modifications to the lifestyle of pregnant women might impart far-reaching benefits to the health of their children. As more information is discovered, more successful management of hypertension can be expected to follow; however, while pregnancy complications such as fetal growth restriction, preeclampsia, preterm birth, etc., continue to occur, their offspring will be at increased risk for hypertension. This article reviews the current knowledge surrounding the developmental origins of hypertension, with a focus on mechanistic pathways and targets for therapeutic and pharmacologic interventions.

Maternal protein restriction during gestation and lactation programs offspring ovarian steroidogenesis and folliculogenesis in the prepubertal gilts

Maternal malnutrition may disrupt ovarian functions in adult offspring. Steroidogenesis and folliculogenesis in the offspring ovary appear to be the major targets of nutritional programming. Nevertheless, the mechanism by which maternal low-protein diet affects the offspring steroidogenesis and folliculogenesis, and the possible pathway linking these two processes remain unclear. In this study, Landrace×Yorkshire crossbred sows were fed either standard (SP) or low-protein (LP, 50% of the SP) diets throughout gestation and lactation. Female offspring were fed the same diet after weaning until 6 months of age. LP offspring had higher serum 17β-estradiol level (P<0.01), which was accompanied by lower mRNA (P<0.05) but higher protein (P<0.05) expression of cytochrome P450 aromatase (CYP19A1) in the ovary. CYP19A1 protein up-regulation was associated with lower ovarian expression of drosha (P<0.05) and miRNAs targeting CYP19A1 (P<0.05). LP offspring had less graafian follicles with more apoptotic granulosa cells (P<0.05), as well as higher caspase 3 activity (P<0.05) and FasL expression (P<0.05) in the ovary. FasL gene up-regulation was associated with higher ERα protein expression (P<0.05) and binding to FasL gene promoter. These results suggest that a maternal LP diet in pregnancy and lactation elevated serum 17β-estradiol level by activating CYP19A1 through miRNA-mediated mechanism, and induced granulosa apoptosis in graafian follicles through ER-activated Fas/FasL-caspase 3 pathway.

Maternal protein restriction during pregnancy and/or lactation negatively affects follicular ovarian development and steroidogenesis in the prepubertal rat offspring

BACKGROUND AND AIMS

Maternal protein restriction during rat pregnancy and lactation is associated with alterations in reproductive function of female offspring including delayed onset of puberty, decreased fertility and premature reproductive aging. These alterations may be related to ovarian prepubertal development, distribution of follicle populations and their steroidogenic capacities. We undertook this study to evaluate the ovarian function of prepubertal female offspring exposed to maternal protein restriction during pregnancy and/or lactation.

METHODS

Adult female Wistar rats were fed a control (C-20% casein diet) or restricted isocaloric diet (R-10% casein) during pregnancy--first letter--and lactation--second letter, to form four groups, CC, RR, CR, RC. Ovaries were collected from 21-day-old female offspring. Preantral and antral follicles were quantified and mRNA expression of key genes involved in follicular development and steroidogenesis (gonadotropin receptors, StAR, P450scc and P450 aromatase) was evaluated. Serum gonadotropin levels were measured.

RESULTS

Significantly decreased numbers of preantral and antral follicles were observed in CR and RC ovaries compared with CC. LH levels were lower and FSH higher in CR pups. mRNA expression of LH receptor (LH-R) was decreased in RR in comparison with the other groups. CR and RC expressed higher StAR, RC increased and RR decreased P450scc, whereas RR and CR decreased aromatase expression in comparison with CC.

CONCLUSIONS

Maternal protein restriction influences prepubertal ovarian follicular number and steroidogenic function in the rat offspring, although RR and CR nutritional schemes have similar outcomes, the mechanisms affecting ovarian function are at different levels of the hypothalamic-pituitary-ovarian axis.

Nutritional programming of pancreatic β-cell plasticity

Nutritional insufficiency during pregnancy has been shown to alter the metabolism of the offspring and can increase the risk of type 2 diabetes. The phenotype in the offspring involves changes to the morphology and functional capacity of the endocrine pancreas, and in the supporting islet microvasculature. Pancreatic β-cells possess a plastic potential and can partially recover from catastrophic loss. This is partly due to the existence of progenitors within the islets and the ability to generate new islets by neogenesis from the pancreatic ducts. This regenerative capacity is induced by bone marrow-derived stem cells, including endothelial cell progenitors and is associated with increased angiogenesis within the islets. Nutritional insults in early life, such as feeding a low protein diet to the mother, impair the regenerative capacity of the β-cells. The mechanisms underlying this include a reduced ability of β-cells to differentiate from the progenitor population, changes in the inductive signals from the microvasculature and an altered presence of endothelial progenitors. Statin treatment within animal models was associated with angiogenesis in the islet microvasculature, improved vascular function and an increase in β-cell mass. This demonstrates that reversal of the impaired β-cell phenotype observed following nutritional insult in early life is potentially possible.