Maternal high-fat diet is associated with impaired fetal lung development.

Maternal nutrition has a profound long-term impact on infant health. Poor maternal nutrition influences placental development and fetal growth, resulting in low birth weight, which is strongly associated with the risk of developing chronic diseases, including heart disease, hypertension, asthma, and type 2 diabetes, later in life. Few studies have delineated the mechanisms by which maternal nutrition affects fetal lung development. Here, we report that maternal exposure to a diet high in fat (HFD) causes placental inflammation, resulting in placental insufficiency, fetal growth restriction (FGR), and inhibition of fetal lung development. Notably, pre- and postnatal exposure to maternal HFD also results in persistent alveolar simplification in the postnatal period. Our novel findings provide a strong association between maternal diet and fetal lung development.

High-density lipoprotein promotes endothelial cell migration and reendothelialization via scavenger receptor-B type I.

Vascular disease risk is inversely related to circulating levels of high-density lipoprotein (HDL) cholesterol. However, the mechanisms by which HDL provides vascular protection are unclear. The disruption of endothelial monolayer integrity is an important contributing factor in multiple vascular disorders, and vascular lesion severity is tempered by enhanced endothelial repair. Here, we show that HDL stimulates endothelial cell migration in vitro in a nitric oxide-independent manner via scavenger receptor B type I (SR-BI)-mediated activation of Rac GTPase. This process does not require HDL cargo molecules, and it is dependent on the activation of Src kinases, phosphatidylinositol 3-kinase, and p44/42 mitogen-activated protein kinases. Rapid initial stimulation of lamellipodia formation by HDL via SR-BI, Src kinases, and Rac is also demonstrable. Paralleling the in vitro findings, carotid artery reendothelialization after perivascular electric injury is blunted in apolipoprotein A-I(-/-) mice, and reconstitution of apolipoprotein A-I expression rescues normal reendothelialization. Furthermore, reendothelialization is impaired in SR-BI(-/-) mice. Thus, HDL stimulates endothelial cell migration via SR-BI-initiated signaling, and these mechanisms promote endothelial monolayer integrity in vivo.

Estrogen causes dynamic alterations in endothelial estrogen receptor expression.

Estrogen receptor (ER)alpha mediates many of the effects of estrogen on the vascular endothelium. The purpose of the present study was to determine whether estrogen modifies endothelial ERalpha expression. In experiments in cultured ovine endothelial cells, physiological concentrations of 17beta-estradiol (E2, 10(-10) to 10(-8) mol/L) caused an increase in ERalpha protein abundance that was evident after 6 hours of hormone exposure. Shorter (2-hour) E2 treatment caused ERalpha downregulation. In contrast to the upregulation in ERalpha after long-term E2, the expression of the other ER isoform, ERbeta, was downregulated. Both nonselective ER antagonism with ICI 182,780 and the inhibition of gene transcription with actinomycin D blocked the increase in ERalpha with E2. In studies using the human ERalpha gene promoter P-1 coupled to luciferase, an increase in ERalpha gene transcription was evident in endothelial cells within 4 hours of E2 exposure. The transcriptional activation was fully blocked by ICI 182,780, whereas the specific ERbeta antagonist RR-tetrahydrochrysene yielded partial blockade. Overexpression of ERalpha or ERbeta caused comparable 10- and 8-fold increases, respectively, in ERalpha promoter activation by E2. Thus, long-term exposure to E2 upregulates ERalpha expression in endothelial cells through the actions of either ERalpha or ERbeta on ERalpha gene transcription; in contrast, E2 causes ERbeta downregulation in the endothelium. We postulate that E2-induced changes in ERalpha and ERbeta expression modify the effects of the hormone on vascular endothelium.

Distinct hypothalamic neurons mediate estrogenic effects on energy homeostasis and reproduction.

Estrogens regulate body weight and reproduction primarily through actions on estrogen receptor-α (ERα). However, ERα-expressing cells mediating these effects are not identified. We demonstrate that brain-specific deletion of ERα in female mice causes abdominal obesity stemming from both hyperphagia and hypometabolism. Hypometabolism and abdominal obesity, but not hyperphagia, are recapitulated in female mice lacking ERα in hypothalamic steroidogenic factor-1 (SF1) neurons. In contrast, deletion of ERα in hypothalamic pro-opiomelanocortin (POMC) neurons leads to hyperphagia, without directly influencing energy expenditure or fat distribution. Further, simultaneous deletion of ERα from both SF1 and POMC neurons causes hypometabolism, hyperphagia, and increased visceral adiposity. Additionally, female mice lacking ERα in SF1 neurons develop anovulation and infertility, while POMC-specific deletion of ERα inhibits negative feedback regulation of estrogens and impairs fertility in females. These results indicate that estrogens act on distinct hypothalamic ERα neurons to regulate different aspects of energy homeostasis and reproduction.