María F. Garcés

Regulation of visceral adipose tissue-derived serine protease inhibitor by nutritional status, metformin, gender and pituitary factors in rat white adipose tissue

Visceral adipose tissue‐derived serine protease inhibitor (vaspin) is a recently discovered adipocytokine mainly secreted from visceral adipose tissue, which plays a main role in insulin sensitivity. In this study, we have investigated the regulation of vaspin gene expression in rat white adipose tissue (WAT) in different physiological (nutritional status, pregnancy, age and gender) and pathophysiological (gonadectomy, thyroid status and growth hormone deficiency) settings known to be associated with energy homeostasis and alterations in insulin sensitivity. We have determined vaspin gene expression by real‐time PCR. Vaspin was decreased after fasting and its levels were partially recovered after leptin treatment. Chronic treatment with metformin increased vaspin gene expression. Vaspin mRNA expression reached the highest peak at 45 days in both sexes after birth and its expression was higher in females than males, but its levels did not change throughout pregnancy. Finally, decreased levels of growth hormone and thyroid hormones suppressed vaspin expression. These findings suggest that WAT vaspin mRNA expression is regulated by nutritional status, and leptin seems to be the nutrient signal responsible for those changes. Vaspin is influenced by age and gender, and its expression is increased after treatment with insulin sensitizers. Finally, alterations in pituitary functions modify vaspin levels. Understanding the molecular mechanisms regulating vaspin will provide new insights into the pathogenesis of the metabolic syndrome.

Expression and regulation of chemerin during rat pregnancy

BACKGROUND Chemerin is an adipocytokine that is expressed in different fat deposits and has been shown to play an important role in adaptive and innate immunity due to its activity as a chemoattractant. Chemerin acts as a ligand for the G protein-coupled receptor chemokine-like receptor 1 (CMKLR1). Chemerin has been shown to regulate the development and metabolic function of adipocytes, liver and muscle tissue. OBJECTIVE There is evidence indicating that several adipocytokines play an important role in placenta. This study aimed to investigate the regulation of chemerin in rat and human placentas throughout gestation. DESIGN AND SETTING Chemerin was examined in rat and human placentas using immunohistochemistry. The chemerin expression pattern in the placenta and adipose tissue of female Sprague Dawley rats on days 12, 16, 19 and 21 of gestation (each of these days represents a group of 12 rats) was determined using TaqMan probe-based quantitative real-time PCR. Rat chemerin serum levels were analyzed with ELISA on days 8, 12, 16, 19 and 21 and compared to virgin controls. RESULTS Chemerin expression was detected in the cytoplasm of rat placental trophoblastic cells and third trimester human placental cytotrophoblast and Hofbauers cells. The serum chemerin levels of rats decreased significantly as gestation progressed. Furthermore, placental chemerin mRNA levels rose significantly at day 16 of gestation and decreased significantly towards the end of the gestation period. CONCLUSION Taken together, this data suggests that chemerin may be an important regulator of maternal-fetal metabolism and metabolic homeostasis during pregnancy.

Irisin Levels During Pregnancy and Changes Associated With the Development of Preeclampsia

CONTEXT Irisin is a recently discovered adipomyokine that regulates the differentiation and phenotype of adipose tissue. OBJECTIVE In this study, we investigated the levels of irisin over the three trimesters of gestation in healthy and preeclamptic women and during the follicular and luteal phase of the menstrual cycle in a cohort of healthy eumenoherric women. METHODS Serum irisin was measured by an ELISA in a longitudinal prospective cohort study in 40 healthy pregnant women, 10 mild preeclamptic women, and 20 healthy eumenoherric women during the menstrual cycle to assess irisin levels and correlations with other metabolic parameters. We identified the protein expression of fibronectin type III domain-containing protein 5, the irisin precursor, in human placenta using immunohistochemical approaches in humans. RESULTS Serum irisin levels are higher in the luteal than in the follicular phase in eumenorrheic women. Fibronectin type III domain-containing protein 5, the irisin precursor, is expressed in human placenta, and its serum levels are higher during the entire pregnancy when compared with nonpregnant women. Serum irisin correlates positively with the homeostasis model assessment of estimated insulin resistance in the first trimester of normal pregnancy. Serum irisin levels do not change throughout gestation in preeclamptic women; however, there were lower irisin levels during the third trimester when compared with the normal pregnant group. CONCLUSION Our results suggest that irisin may be involved in reproductive function and in the pregnancy-associated metabolic changes, and this condition may be an irisin-resistant state during gestation.

Serum chemerin levels during normal human pregnancy

During gestation there are important changes in maternal metabolism and an increase in insulin resistance, coinciding with an increase in adiposity. Chemerin is an adipocytokine which is expressed and secreted in various tissues, including placenta, and may play an important role in metabolic regulation during pregnancy. The aim of this study was to determine serum levels of chemerin during gestation and compare them to other indicators of insulin resistance. A cross-sectional study was carried out analyzing serum chemerin levels of 20 pregnant women during three gestational periods, early, middle, and late (between the 10th and 14th, the 23rd and 26th, and the 34th and 37th week) and 20 non-pregnant women were used as a control group. An analysis of chemerin levels during the menstrual cycle was performed in an eumenorrheic group (n=16) in the early follicular (cycle day 4±1) and the midluteal phase (cycle day 22±1), demonstrating that serum chemerin levels did not fluctuate significantly. Serum levels of chemerin were significantly elevated during late gestation when compared to early (P<0.001) and middle (P=0.001) gestation and a negative correlation between serum chemerin and adiponectin levels (r=-0.1643) became more significant when the non-pregnant group was included in the calculations (r=-0.2471). There was no significant association of triglycerides, total cholesterol, LDL, HDL, insulin, and HOMA levels with chemerin. Although chemerin rose significantly and is negatively associated with adiponectin levels, it is not correlated with other markers of insulin sensitivity, suggesting that more study is needed to determine whether chemerin is useful in predicting insulin resistance during gestation.

Food intake regulating-neuropeptides are expressed and regulated through pregnancy and following food restriction in rat placenta

BackgroundNeuropeptide Y (NPY), agouti related peptide (AgRP), cocaine and amphetamine-regulated transcript (CART) and melanocortins, the products of the proopiomelanocortin (POMC), are hypothalamic peptides involved in feeding regulation and energy homeostasis. Recent evidence has demonstrated their expression in rat and human placenta.MethodsIn the current study, we have investigated the expression of those neuropeptides in the rat placenta by real-time PCR using a model of maternal food restriction.ResultsOur results showed that placental-derived neuropeptides were regulated through pregnancy and following food restriction.ConclusionThese data could indicate that placental-derived neuropeptides represent a local regulatory circuit that may fine-tune control of energy balance during pregnancy.

Expression of neuropeptide W in rat stomach mucosa : Regulation by nutritional status, glucocorticoids and thyroid hormones

Neuropeptide W (NPW) is a recently identified neuropeptide that binds to G-protein-coupled receptor 7 (GPR7) and 8 (GPR8). In rodent brain, NPW mRNA is confined to specific nuclei in hypothalamus, midbrain and brainstem. Expression of NPW mRNA has also been confirmed in peripheral organs such as stomach. Several reports suggested that brain NPW is implicated in the regulation of energy and hormonal homeostasis, namely the adrenal and thyroid axes; however the precise physiological role and regulation of peripheral NPW remains unclear. In this study, we examined the effects of nutritional status on the regulation of NPW in stomach mucosa. Our results show that in this tissue, NPW mRNA and protein expression is negatively regulated by fasting and food restriction, in all the models we studied: males, females and pregnant females. Next, we examined the effect of glucocorticoids and thyroid hormones on NPW mRNA expression in the stomach mucosa. Our data showed that NPW expression is decreased in this tissue after glucocorticoid treatment or hyperthyroidism. Conversely, hypothyroidism induces a marked increase in the expression of NPW in rat stomach. Overall, these data indicate that stomach NPW is regulated by nutritional and hormonal status.

Brain‐derived neurotrophic factor is expressed in rat and human placenta and its serum levels are similarly regulated throughout pregnancy in both species

Pregnancy is characterized by several metabolic changes that promote fat gain and later onset of insulin resistance. As Brain‐derived neurotrophic factor (BDNF) decreases hyperglycaemia and hyperphagia, we aimed to investigate the potential role of placental and circulating BDNF levels in these pregnancy‐related metabolic changes in rats and humans.

Adiponectin receptor 2 is regulated by nutritional status, leptin and pregnancy in a tissue-specific manner.

The aim of the present work was to study the regulation of circulating adiponectin levels and the expression of adiponectin receptor 2 (Adipo-R2) in several rat tissues in relation to fasting, leptin challenge, pregnancy, and chronic undernutrition. Using real-time PCR, we found Adipo-R2 mRNA expression in the liver, stomach, white and brown adipose tissues (WAT and BAT) of adult rats. Immunohistochemical studies confirmed protein expression in the same tissues. Adipo-R2 mRNA levels were decreased in liver after fasting, with no changes in the other tissues. Leptin decreased Adipo-R2 expression in liver and stomach, but increased its expression in WAT and BAT. Chronic caloric restriction in normal rats increased Adipo-R2 gene expression in stomach, while it decreased hepatic Adipo-R2 levels in pregnant rats. Using radioimmunoassay, we found that plasma adiponectin levels were diminished by fasting and leptin. Conversely, circulating adiponectin was increased in food-restricted rats, whereas its levels decreased in food-restricted pregnant rats by the end of gestation. In conclusion our findings provide the first evidence that (a) Adipo-R2 mRNA is regulated in a tissue-specific manner by fasting, but leptin is not responsible for those changes; (b) chronic caloric restriction in normal and pregnant rats also regulate Adipo-R2 mRNA in a tissue-specific manner; and (c) Adipo-R2 mRNA does not show a clear correlation with plasma adiponectin levels.

Serum Endoglin Levels in Patients Suffering from Systemic Sclerosis and Elevated Systolic Pulmonary Arterial Pressure

Background. Pulmonary arterial hypertension (PAH) is the main cause of morbimortality in systemic sclerosis (SSc). Increased Eng expression has been demonstrated in SSc patients. Objective. Ascertaining serum levels of Eng in SSc patients with and without elevated systolic pulmonary arterial pressure (sPAP) and comparing them with that of healthy volunteers. Methods. A cross-sectional study was carried out. A commercial ELISA kit was used for measuring serum concentrations of Eng in 60 subjects: 40 patients with SSc with and without elevated sPAP, compared to 20 healthy control subjects. Elevated sPAP was detected by echocardiogram. Results. No association between positive Eng and elevated sPAP was found when compared to the SSc without elevated sPAP group (OR = 2.85; 0.65–12.88 95% CI; P = .11); however, an association was found between positive Eng and elevated sPAP compared to healthy controls (OR = 23.22; 2.46–1050.33 95% CI; P = .001), and weak association was found between the positive Eng with SSc without elevated sPAP group compared to healthy controls (OR = 8.14, 0.8–393.74 95% CI; P = .046). Conclusion. Raised serum levels of Eng in SSc patients compared to healthy controls were found, suggesting a role for Eng in SSc vasculopathy and not just in elevated sPAP. However, prospective studies are needed to verify such observations.

Regulation of NucB2/Nesfatin-1 throughout rat pregnancy

Nesfatin-1 is an anorexigenic neuropeptide derived by post-translational cleavage from the N-terminus region DNA binding/EF-hand/acidic amino acid rich region (NEFA)/nucleobindin2 (NucB2) protein through proteolytic prohormone convertases. This neuropeptide was originally localized in different appetite controlling areas such as the hypothalamic paraventricular nucleus, arcuate nucleus, supraoptic nucleus, lateral hypothalamic area, and nucleus tractus solitarius. The objective of this study was to determine the expression and the changes that occur to mRNA and protein of NucB2 and Nesfatin-1 serum levels during gestation. This study utilized molecular and immunological approaches to investigate the expression and regulation of NucB2/Nesfatin-1 protein throughout gestation in rat fed under ad libitum and food restricted conditions (30% nutrient restriction). NucB2 was immunolocalized in the amnion and decidua of the rat placenta. Nesfatin-1 serum levels were measured by radioimmunoassay on gestational days 12, 16, 19 and 21, showing a significant (p<0.01) decrease in serum levels after day 12 until the end of gestation in rats fed ad libitum. These results were correlated with the analysis of NucB2 mRNA, with a significant (p<0.01) reduction observed in both the mRNA and protein of NucB2 during the gestational days 12, 16 and 21. It was also observed that food restriction decreases Nesfatin-1 serum levels and NucB2 placental expression at day 16 of gestation when compared to pregnant rats fed ad libitum. This study illustrates for the first time through molecular and immunological approaches the NucB2 expression and regulation on rat placenta and that this peptide is regulated throughout pregnancy. Consistent with previous reports, our results provide additional evidence supporting the role of NucB2 protein as an anorexigenic peptide that may contribute to the regulation of feeding behavior and energy homeostasis. NucB2/Nesfatin-1 might play an important metabolic role during pregnancy and fetal development and its energy balance mediating role should be studied in various physiological and pathological conditions throughout gestation.