BackgroundExposure of pregnant mothers to elevated concentrations of circulating testosterone levels is associated with fetal growth restriction and delivery of small-for-gestational-age babies. We examined whether maternal testosterone crosses the placenta to directly suppress fetal growth or if it modifies placental function to reduce the capacity for transport of nutrients to the fetus.MethodsPregnant rats were exposed to testosterone propionate (TP; 0.5 mg/kg) by daily subcutaneous injection from gestational days (GD) 15-19. Maternal and fetal testosterone levels, placental nutrient transport activity and expression of transporters and birth weight of pups and their anogenital distances were determined.ResultsThis dose of TP doubled maternal testosterone levels but had no effect on fetal testosterone levels. Maternal daily weight gain was significantly lower only on GD 19 in TP treated dams compared to controls. Placental weight and birth weight of pups were significantly reduced, but the anogenital distance of pups were unaffected by TP treatment. Maternal plasma amino acids concentrations were altered following testosterone exposure, with decreases in glutamine, glycine, tyrosine, serine, proline, and hydroxyproline and increases in asparagine, isoleucine, leucine, lysine, histidine and arginine. In the TP dams, placental system A amino acid transport activity was significantly reduced while placental glucose transport capacity was unaffected. Decreased expression of mRNA and protein levels of slc38a2/Snat2, an amino acid transporter, suggests that reduced transporter proteins may be responsible for the decrease in amino acid transport activity.ConclusionsTaken together, these data suggest that increased maternal testosterone concentrations do not cross the placenta to directly suppress fetal growth but affects amino acid nutrient delivery to the fetus by downregulating specific amino acid transporter activity.

Intrauterine undernutrition plays a role in the development of adult hypertension. Most studies are done in male offspring to delineate the mechanisms whereby blood pressure may be raised; however, the vascular mechanisms involved in female offspring are unclear. Female offspring of pregnant Sprague-Dawley rats fed either a control (C; 18%) or a low-protein (LP; 6%) diet during pregnancy were used. Birth weight and later growth were markedly lower in LP than in C offspring. LP offspring exhibited impaired estrous cyclicity with increased mean arterial pressure. Hypotensive response to acetylcholine (ACh) and the hypertensive response to phenylephrine (PE) were greater in LP than in C rats. N-nitro-L-arginine methyl ester (L-NAME) induced greater hypertensive responses in C than in LP rats. Endothelium-intact mesenteric arteries from LP offspring exhibited increased contractile responses to PE and reduced vasodilation in response to ACh. In endothelium-denuded arteries, relaxation responses to sodium nitroprusside were similar in both groups. Basal and ACh-induced increase in vascular nitrite/nitrate production was lower in LP than in C offspring. L-NAME or 1H-1,2,4-oxadiazolo-4,3-quinoxalin-1-one inhibited ACh relaxations and enhanced PE contractions in C offspring, but had minimal effect in LP rats. The decreasedNO-mediated vascular response might explainthe increased vascular contraction and arterial pressure infemale offspring with low birth weight.

Aims The influence of prenatal factors on the development of arterial hypertension has gained considerable interest in recent years. We examined the effects of prenatal testosterone treatment on blood pressure in adult female rats. Further, to define the mechanisms whereby blood pressure may be raised, we examined vascular endothelial function and nitric oxide synthesis. Methods and Results Testosterone propionate (0.5mg/kg/day;SC) or vehicle was administered to pregnant Sprague-Dawley rats from gestational day 15–19. Maternal feed intake and plasma levels of steroid hormones were measured in the dams. In the female offspring, birth weight, growth rate, blood pressure, vascular reactivity, eNOS expression, and nitric oxide production were examined. In the pregnant rats, testosterone-treatment increased plasma testosterone levels by 2-fold without any significant changes in 17β-estradiol, progesterone and corticosterone levels. Testosterone-treatment did not affect maternal feed intake. The pups born to testosterone mothers were smaller in size but exhibited catch-up growth. The blood pressure in the testosterone offspring at 6 months of age was significantly higher compared to controls. Endothelium-intact mesenteric arteries from testosterone group exhibited increased contractile responses to phenylephrine, decreased vasodilation to acetylcholine and unaltered responses to sodium nitroprusside in comparison to control rats. Testosterone rats demonstrated decreased expression for eNOS, and reduced nitric oxide production. Conclusions Our data show that elevated plasma maternal testosterone levels: (1) causes low birth weight followed by catch-up growth and hypertension in female offspring; (2) alters endothelium-dependent vascular responses. The endothelial dysfunction is associated with decreased activity/expression of eNOS.

We previously reported that gestational dietary protein restriction in rats causes gender-related differences in development of offspring's blood pressure (BP) that is more pronounced in the males than females. Since such effects may depend on sex hormones, we investigated the role of estradiol in the development of hypertension in female offspring of protein restricted dams. Female offspring of pregnant rats fed normal (20%) or protein restricted (6%) casein diets throughout pregnancy were kept either, intact, ovariectomized or ovariectomized with estradiol supplementation. BP, estradiol and testosterone levels and vascular estrogen receptor (ER) were examined. BP was significantly higher and plasma estradiol levels were significantly lower by 34% in intact protein restricted female offspring compared to corresponding controls. Further decrease in estradiol levels by ovariectomy exacerbated hypertension in the protein restricted females with an earlier onset and more prominent elevation in BP compared to controls. Estradiol supplementation in ovariectomized protein restricted females significantly reversed ovariectomy-induced hypertension but did not normalize BP to control levels. The hypertensive protein restricted females have reduced vascular ERα expression that was unaffected by ovariectomy or estradiol replacement. In addition, the testosterone levels were significantly higher by 2.4-, 3.4-, and 2.8-fold in intact, ovariectomized and estradiol replaced protein restricted females compared to corresponding controls. Our data show that: 1) hypertension in protein restricted adult female offspring is associated with reduced plasma estradiol levels, 2) estradiol protects and limits the severity of hypertension in protein restricted females and contribute for sexual dimorphism, and 3) Estradiol replacement fails to completely reverse hypertension, which may be related to limited availability of vascular ERα receptors and/or increased circulating testosterone levels.

Adrenomedullin2 (ADM2), also referred to as Intermedin (IMD) is expressed in trophoblast cells in human placenta and enhances the invasion and migration of first trimester HTR-8/SV-neo cells. Recently we demonstrated that infusion of IMD antagonist in pregnant rats causes feto-placental growth restriction suggesting a role for IMD in maintaining a successful pregnancy. Therefore, this study was undertaken to assess if IMD has a functional role in embryo implantation in a rat model. We show that IMD mRNA is expressed in rat implantation sites and its expression is significantly higher on day 15 in placenta compared to days 18 – 22. Infusion of IMD antagonist IMD17–47 from day 3 of pregnancy causes a significant decrease in the weights of day 9 implantation sites as well as serum levels of 17β-estradiol, progesterone, nitric oxide and serum MMP2 and MMP9 gelatinase activity. Further, expression of MMP2,MMP9, VEGF and PLGF protein levels are significantly downregulated in the implantation sites of IMD antagonist treated rats. This study suggests a potential involvement of IMD in regulating the factors that are critical for implantation and growth of the embryo and thus in establishment of normal rat pregnancy.