Maternal nutrient restriction in the ewe from early to midgestation programs reduced steroidogenic enzyme expression and tended to reduce progesterone content of corpora lutea, as well as circulating progesterone in nonpregnant aged female offspring

Developmental programming of reproduction in the female animal

Successful reproduction is a cornerstone in food animal industry in order to sustain food production for human. Therefore, various methods focusing on genetics and postnatal environment have been identified and applied to improve fertility in livestock. Yet there is evidence indicating that environmental factors during prenatal and/or neonatal life can also impact the function of reproductive system and fertility in the animals during adulthood, which is called the developmental programming of reproduction. The current review summarizes data associated with the developmental origins of reproduction in the female animals. In this regard, this review focuses on the effect of plane of nutrition, maternal body condition, hypoxia, litter size, maternal age, parity, level of milk production and milk components, lactocrine signaling, stress, thermal stress, exposure to androgens, endocrine disrupting chemicals, mycotoxins and pollutants, affliction with infection and inflammation, and maternal gut microbiota during prenatal and neonatal periods on the neuroendocrine system, puberty, health of reproductive organs and fertility in the female offspring. It is noteworthy that these prenatal and neonatal factors do not always exert their effects on the reproductive performance of the female by compromising the development of organs directly related to reproductive function such as hypothalamus, pituitary, ovary, oviduct and uterus. Since they can impair the development of non-reproductive organs and systems modulating reproductive function as well (e.g., metabolic system and level of milk yield in dairy animals). Furthermore, when these factors affect the epigenetics of the offspring, their adverse effects will not be limited to one generation and can transfer transgenerationally. Hence, pinpointing the factors influencing developmental programming of reproduction and considering them in management of livestock operations could be a potential strategy to help improve fertility in food animals.

Maternal protein restriction impairs nutrition and ovarian histomorphometry without changing p38MAPK and PI3K-AKT-mTOR signaling in adult rat ovaries

AIMS

Because an adequate protein supply is detrimental for the maintenance of folliculogenesis and ovulation, we evaluated the impact of maternal low protein diet on nutritional parameters, estrous cycle, ovarian histomorphometry, and on the expression of metabolic and survival signaling molecules in different follicular stages.

MAIN METHODS

Twenty Wistar pregnant rats were divided into two groups: the normoprotein (NP) group, composed of animals that received 17% protein, and a low-protein (LP) group, composed of animals that received 6% protein during gestation and lactation period. After weaning, female rats were fed with standard diet until the 120-days-old.

KEY FINDINGS

LP animals showed reduced body mass index, total body weight, energy intake, feed efficiency, and visceral fat. The ovarian tissue presented vascular congestion and fat accumulation in the medulla, followed by a significant reduction in the amount of primordial and primary follicles. In addition, the number of atretic follicles was higher in LP than in NP animals. Maternal undernutrition also resulted in increased levels of estradiol (E2) and progesterone (P4) while testosterone (T) was unchanged in the offspring. Although discrete changes in p38MAPK and in PI3K-AKT-mTOR immunostaining were observed in the ovarian follicles and corpus luteum in LP, no differences were found at their protein levels.

SIGNIFICANCE

Maternal protein restriction alters estrous cycle and histomorphometry of the offspring's ovary without changing the levels of intracellular regulatory molecules in adulthood. These morphofunctional changes may alter reproductive performance in female offspring, highlighting maternal dietary conditions as an important factor for offspring reproductive health.

Developmental programming of the female reproductive system-a review

Exposures to adverse conditions in utero can lead to permanent changes in the structure and function of key physiological systems in the developing fetus, increasing the risk of disease and premature aging in later postnatal life. When considering the systems that could be affected by an adverse gestational environment, the reproductive system of developing female offspring may be particularly important, as changes have the potential to alter both reproductive capacity of the first generation, as well as health of the second generation through changes in the oocyte. The aim of this review is to examine the impact of different adverse intrauterine conditions on the reproductive system of the female offspring. It focuses on the effects of exposure to maternal undernutrition, overnutrition/obesity, hypoxia, smoking, steroid excess, endocrine-disrupting chemicals, and pollutants during gestation and draws on data from human and animal studies to illuminate underlying mechanisms. The available data indeed indicate that adverse gestational environments alter the reproductive physiology of female offspring with consequences for future reproductive capacity. These alterations are mediated via programmed changes in the hypothalamic-pituitary-gonadal axis and the structure and function of reproductive tissues, particularly the ovaries. Reproductive programming may be observed as a change in the timing of puberty onset and menopause/reproductive decline, altered menstrual/estrous cycles, polycystic ovaries, and elevated risk of reproductive tissue cancers. These reproductive outcomes can affect the fertility and fecundity of the female offspring; however, further work is needed to better define the possible impact of these programmed changes on subsequent generations.

The effect of pre-breeding vitamin E and selenium injection on reproductive performance, antioxidant status, and progesterone concentration in estrus-synchronized Mehraban ewes

The present study was conducted to assess the effects of pre-breeding vitamin E and selenium (ESe) injections on the reproductive performance, antioxidant status, and serum progesterone (P₄) concentration in estrus-synchronized Mehraban ewes. During the breeding season, 38 ewes (3-4 years) were divided into two groups (n = 18), and the synchronization of estrus was achieved by intravaginal insertion of 0.3 g progesterone CIDR device for 13 days followed by 350 IU eCG at CIDR withdrawal. Ewes were kept under pasture conditions and exposed to Mehraban rams 48 h following CIDR withdrawal. The experimental treatments were control and ESe injection. The ESe group was received three intramuscular (5 mL) injections of Ese (0.5 mg/mL of selenium as sodium selenite and 50 IU vitamin E as DL-α- tocopheryl) once every 2 weeks. Specifically, Ese was administered at 2 weeks before CIDR insertion, at the times of CIDR insertion and CIDR withdrawal. Fertility, prolificacy, lambing rate, and birth weight were recorded after parturition. Blood samples were collected at CIDR insertion, CIDR withdrawal, 5, 10, and 15 days after ram exposure. Fertility, prolificacy, lambing rate, and birth weight did not improve by Ese treatment, but viability of lambs was higher in ESe than control (P < 0.05). Serum total antioxidant capacity at day 5 and P₄ at day 10 after ram exposure was higher in ESe than control (P < 0.05). In conclusion, sheep breeders can use ESe at CIDR insertion and withdrawal times to potentiate antioxidant status and progesterone profile of estrus-synchronized Mehraban ewes.

Developmental Programming of Fertility in Livestock

Developmental programming became an area of interest to understand negative environmental impacts on progeny performance. Recently, the concept that we may be able to harness developmental programming to target animals to their niche in the production system has gained recognition. Female fertility is an area where developmental programming has been moderately successful; however, the mechanisms remain unclear. Although some studies have demonstrated differences in gonadal development and attainment of puberty in response to developmental programming, these have not translated to improved fertility. To improve response to developmental programming, it is critical to identify factors that contribute to inconsistencies across studies.

Developmental Programming, a Pathway to Disease

Accumulating evidence suggests that insults occurring during the perinatal period alter the developmental trajectory of the fetus/offspring leading to long-term detrimental outcomes that often culminate in adult pathologies. These perinatal insults include maternal/fetal disease states, nutritional deficits/excess, stress, lifestyle choices, exposure to environmental chemicals, and medical interventions. In addition to reviewing the various insults that contribute to developmental programming and the benefits of animal models in addressing underlying mechanisms, this review focuses on the commonalities in disease outcomes stemming from various insults, the convergence of mechanistic pathways via which various insults can lead to common outcomes, and identifies the knowledge gaps in the field and future directions.

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.