Vitamin A deficiency during rat pregnancy alters placental TNF-alpha signalling and apoptosis

Retinoic acid and fibroblast growth factor-2 play a key role on modulation of sex hormones and apoptosis in a mouse model of polycystic ovary syndrome induced by estradiol valerate

OBJECTIVE

The main goal of the present study is to investigate the effects of retinoic acid and fibroblast growth factor-2 on serum levels of FSH and LH, histology, and apoptosis in the mouse model of Poly Cystic Ovary Syndrome (PCOS).

MATERIALS AND METHODS

80 female NMRI mice have been randomly divided into eight groups. Group 1 received normal saline as a control, and Group 2 received estradiol valerate (EV) at 4 mg/100 g of body weight. Moreover, Groups 3-4 were administered with RA (a dose of 0.05 μg/μl) and FGF2 (a dose of 0.01 μg/kg), respectively. Groups 5 and 6 respectively received the EV plus the RA (0.05 μg/μl) and FGF2 (0.01 μg/kg). Group 7 received the RA and FGF2 at doses corresponding to healthy mice, and Group 8 received the EV plus the RA + FGF2 (similar to previous doses). RA and FGF2 were injected three times per week for four weeks. Finally, histological and immunohistological parameters of the ovary were evaluated.

RESULTS

The study revealed that both single and combined injection of fibroblast growth factor-2 (FGF2) and retinoic acid (RA) in groups 5, 6, and 8 significantly reduced follicular diameters compared to group 2. Measurements confirmed that simultaneous injection of RA and FGF2 into polycystic mice significantly increased antral follicles, corpus luteum (CL), epithelial thickness, and oocyte diameter as well as decreased cystic follicles. Positive TUNEL cells that were considerably increased in the antral follicle of group 2 significantly decreased in the RA and FGF2 recipient groups, either alone or in combination. Besides, the injection of FGF2 increased preantral follicles and CL.

CONCLUSION

The findings of the present investigation reveal that injection of RA and FGF2 has both protective and ameliorative effects that can promise new therapies for women with PCOS.

Vitamin A Requirements in Pregnancy and Lactation

Pregnancy and lactation are critical life stages with unique nutritional requirements, including for vitamin A (VA). Current DRIs for VA were published in 2001. The objective of this review was to identify and categorize evidence related to VA requirements in pregnancy and lactation since these DRIs were formulated. We searched MEDLINE and included articles according to an analytic framework of maternal VA exposure on status and health outcomes in the mother-child dyad. Intermediate and indirect evidence supports that maternal VA intakes can impact the mother's VA status, breastmilk, and health outcomes, as well as the child's VA status and select health outcomes. Food-based approaches can lead to more sustained, sufficient VA status in mothers and children. Research needs include further study linking maternal VA intakes on maternal and child VA status, and further associations with outcomes to determine intake requirements to optimize health.

Effects of micronutrients on placental function: evidence from clinical studies to animal models

Micronutrient deficiencies are common in pregnant women due to low dietary intake and increased requirements for fetal development. Low maternal micronutrient status is associated with a range of pregnancy pathologies involving placental dysfunction, including fetal growth restriction (FGR), small-for-gestational age (SGA), pre-eclampsia and preterm birth. However, clinical trials commonly fail to convincingly demonstrate beneficial effects of supplementation of individual micronutrients, attributed to heterogeneity and insufficient power, potential interactions and lack of mechanistic knowledge of effects on the placenta. We aimed to provide current evidence of relationships between selected micronutrients (vitamin D, vitamin A, iron, folate, vitamin B12) and adverse pregnancy outcomes, combined with understanding of actions on the placenta. Following a systematic literature search, we reviewed data from clinical, in vitro and in vivo studies of micronutrient deficiency and supplementation. Key findings are potential effects of micronutrient deficiencies on placental development and function, leading to impaired fetal growth. Studies in human trophoblast cells and rodent models provide insights into underpinning mechanisms. Interestingly, there is emerging evidence that deficiencies in all micronutrients examined induce a pro-inflammatory state in the placenta, drawing parallels with the inflammation detected in FGR, pre-eclampsia, stillbirth and preterm birth. Beneficial effects of supplementation are apparent in vitro and in animal models and for combined micronutrients in clinical studies. However, greater understanding of the roles of these micronutrients, and insight into their involvement in placental dysfunction, combined with more robust clinical studies, is needed to fully ascertain the potential benefits of supplementation in pregnancy.

Effect of Cadmium on Trophoblast Cell Proliferation and Apoptosis in Different Gestation Periods of Rat Placenta

In this study, we aimed to show how cadmium (Cd) affects the trophoblast proliferation and differentiation in the placenta and the apoptotic activity in different gestational days and, hence, its effects of placental development with immunohistochemical and TUNEL techniques. Experimental model of our study consisted of placental development of control and Cd groups on 15, 17, 19, and 21th days of the gestation. Female rats in Cd groups were subcutaneously administered a single dose of 0.5 mg Cd/kg/day dissolved in sodium chloride as 2 mL/kg Cd chloride until the day they sacrificed. Embryo and placenta of female rats were separately removed on 15, 17, 19, and 21th days of the gestation in which the placental development takes place and placentas were processed for microscopic examinations. In the placentas of the control group, all layers were observed to be formed on the 15th gestational day and thereafter a continuous growth was monitored. In the Cd group also all layers existed from the 15th gestational day. However, they were smaller in size than control groups. Frequency of proliferating cell nuclear antigen (PCNA)-positive cells was decreased and the number of apoptotic cells was increased in all the gestational days related to Cd. In conclusion, Cd administered during the pregnancy was observed to cause abnormal placental development by disrupting the normal structure of the placenta, inhibiting the proliferation of trophoblast and increasing the number of apoptotic trophoblast cells.

Choline inadequacy impairs trophoblast function and vascularization in cultured human placental trophoblasts

Maternal choline intake during gestation may influence placental function and fetal health outcomes. Specifically, we previously showed that supplemental choline reduced placental and maternal circulating concentrations of the anti-angiogenic factor, fms-like tyrosine kinase-1 (sFLT1), in pregnant women as well as sFLT1 production in cultured human trophoblasts. The current study aimed to quantify the effect of choline on a wider array of biomarkers related to trophoblast function and to elucidate possible mechanisms. Immortalized HTR-8/SVneo trophoblasts were cultured in different choline concentrations (8, 13, and 28 µM [control]) for 96-h and markers of angiogenesis, inflammation, apoptosis, and blood vessel formation were examined. Choline insufficiency altered the angiogenic profile, impaired in vitro angiogenesis, increased inflammation, induced apoptosis, increased oxidative stress, and yielded greater levels of protein kinase C (PKC) isoforms δ and ϵ possibly through increases in the PKC activators 1-stearoyl-2-arachidonoyl-sn-glycerol and 1-stearoyl-2-docosahexaenoyl-sn-glycerol. Notably, the addition of a PKC inhibitor normalized angiogenesis and apoptosis, and partially rescued the aberrant gene expression profile. Together these results suggest that choline inadequacy may contribute to placental dysfunction and the development of disorders related to placental insufficiency by activating PKC.

Retinoic acid-metabolizing enzyme cytochrome P450 26a1 (cyp26a1) is essential for implantation: functional study of its role in early pregnancy

Vitamin A (VA) is required for normal fetal development and successful pregnancy. Excessive VA intake during pregnancy may lead to adverse maternal and fetal effects. Cytochrome P450 26A1 (cyp26a1), a retinoic acid (RA)-metabolizing enzyme, is involved in VA metabolism. It has been shown that cyp26a1 is expressed in female reproductive tract, especially in uterus. In order to investigate the role of cyp26a1 during pregnancy, we constructed a recombinant plasmid DNA vaccine encoding cyp26a1 protein and immunized mice with the plasmid. Compared to control groups, the pregnancy rate of the cyp26a1 plasmid-immunized mice were significantly decreased (P < 0.01). Further results showed that both cyp26a1 mRNA and protein were specifically induced in the uterus during implantation period and localized in the uterine luminal epithelium. Importantly, the number of implantation sites was also significantly reduced (P < 0.05) after the uterine injection of cyp26a1-specific antisense oligos or anti-cyp26a1 antibody on day 3 of pregnancy. Accordingly, the expression of RA-related cellular retinoic acid binding protein 1 and tissue transglutaminase was markedly increased (P < 0.05) in the uterine luminal epithelium after intrauterine injection treatments. These data demonstrate that uterine cyp26a1 activity is important for the maintenance of pregnancy, especially during the process of blastocyst implantation.

Gestation linked radical oxygen species fluxes and vitamins and trace mineral deficiencies in the ruminant

In mammals, radical oxygen species (ROS) are essential factors of cell replication, differentiation and growth (oxidative signal), notably during gestation, but are also potentially damaging agents. In Women, ROS play a role in remodeling of uterine tissues, implantation of the embryo, settlement of the villi and development of blood vessels characteristic of gestation. The body stores of vitamins and minerals of gestating females are used to keep ROS fluxes at a level corresponding to oxidative signals and to prevent an imbalance between their production and scavenging (oxidative stress), which would be detrimental to the mother and fetus. There is some evidence that, although based on different regulatory mechanisms, most of the effects of ROS reported in humans also occur in pregnant ruminant females, some of which have been actually reported. Many vitamins and trace elements have dual effects in the organism of mammals: (a) they are involved in the control of metabolic pathways or/and gene expression, (b) but most of the time they also display ROS trapping activity or their deficiencies induce high rates of ROS production. Deficiencies induce different disorders of gestation and can be induced by different kinds of stress. An example is given, corresponding to the decreased contents of cobalt of forages, when exposed to sustained heavy rains, so that the supply of vitamins B12 to the organism of the ruminant that grazes them is reduced and failure of gestation is induced. Outdoor exposure of ruminants to adverse climatic conditions by itself can increase the vitamin and trace element requirements. Adaptation of production systems taking into account these interactions between gestation and sources of stress or change of the quality of feeding stuffs as well as further developments of knowledge in that field is necessary to promote sustainable agricultural practices.

Fetal nutrition: a review

Knowledge of fetal nutrient supply has greatly increased in the last decade due to the availability of fetal blood samples obtained under relatively steady-state conditions. These studies, together with studies utilizing stable isotope methodologies, have clarified some aspects of the supply of the major nutrients for the fetus such as glucose, amino acids and fatty acids. At the same time, the relevance of intrauterine growth has been recognized not only for the well-being of the neonate and child, but also for later health in adulthood. The major determinants of fetal nutrient availability are maternal nutrition and metabolism together with placental function and metabolism. The regulation of the rate of intrauterine growth is the result of complex interactions between genetic inheritance, endocrine environment and availability of nutrients to the fetus.