Placental expression of substance P and vasoactive intestinal peptide: evidence for a local effect on hormone release.

The present study evaluated vasoactive intestinal peptide (VIP) and substance P (SP) mRNA expressions and the localization of both peptides in first- and third-trimester human placentas. VIP and SP mRNAs were detected by slot blot analysis in first- and third-trimester placental tissues. By immunohistochemistry both neuropeptides were localized in the trophoblast (syncytium and cytotrophoblastic cells) of the chorionic villi. Because little information is available on the role of VIP and/or SP on the secretion of placental hormones, we investigated the effect of these neuropeptides on human chorionic gonadotropin (hCG) and progesterone release from primary cultured human trophoblastic and JEG-3 cells. The addition of increasing doses of VIP resulted in a dose-dependent stimulation of hCG release from cultured human trophoblast and JEG-3 cells. Increasing doses of VIP also dose-dependently stimulated progesterone secretion from primary cultured trophoblastic cells at all time points evaluated and from JEG-3 cells only after 3 h. SP did not affect hCG and progesterone secretion either in cultured human trophoblast or in JEG-3 cells. In conclusion, the present study demonstrates that VIP and SP are mainly expressed in human trophoblasts, and that VIP modulates the in vitro secretion of hCG and progesterone, suggesting a different role in trophoblastic function of the two peptides.

Fibronectins and basal lamina molecules expression in human subcutaneous white adipose tissue.

Adipose tissue is a type of connective tissue whose extracellular matrix (ECM) components are poorly characterized in vivo. Several in vitro studies have suggested a regulatory role for the ECM molecules during adipocyte differentiation. Since no data are available concerning the in vivo expression of the main ECM components such as fibronectin, collagen IV, laminin and heparan sulfate proteoglycan in the adipose tissue, we investigated the presence of these molecules by immunohistochemistry. We show that fibronectin isoforms are not expressed in fully differentiated subcutaneous adipocytes whereas collagen IV, laminin and heparan sulfate are detectable around single adipocytes, i.e. in the region corresponding to the basement membrane. These data are supported by previous in vitro studies showing a strong decrease of fibronectin synthesis during adipocyte development whereas basement membrane molecules seem to increase during adipocyte differentiation.

Influence of body mass on glycemic control in a type 2 diabetic population: a 3-year follow-up.

Obesity is often associated with type 2 (non insulin-dependent) diabetes. A growing body of evidence support the hypothesis that these two diseases share a common pathogenesis. Nevertheless, experience derived from clinical observation on type 2 diabetic patients indicates that reduction of body weight is not always accompanied by an improvement in metabolic control and that a good metabolic control is often obtained without influencing body composition. Aim of the present study was to evaluate the relationship between body mass and glycemic control in a type 2 diabetic population by a 3 years observational study. A cohort of 562 subjects was studied. At entry more than 80% of patients were overweight or obese according to the body mass index (BMI) scale and this proportion was not significantly reduced at the end of the follow-up. At entry all patients had a glycosylated hemoglobin (HbA1c) value above 8.1% whereas at the end of follow-up more than 2/3 of patients were in good metabolic control. No relationship was observed between modification of body mass and metabolic control. These data confirm the high frequency of obesity among type 2 diabetic individuals but they suggest that impaired glucose metabolism and alteration of body weight have different pathogenesis.

Villous sprouting: fundamental mechanisms of human placental development.

There is increasing evidence that maldevelopment of the placental villous tree can play an important role in the pathogenesis of various pregnancy diseases. In this review we present the most recent advances of cellular and molecular mechanisms involved in the early formation of chorionic villi. In particular we focus our attention on the structural events during early villous sprouting leading to the formation of the mesenchymal villi which are the forerunners of all other villous types, i.e. immature intermediate villi, stem villi, mature intermediate villi and terminal villi. Early villous sprouting starts as 'hot spots' which are circumscribed areas consisting of highly proliferating cytotrophoblastic and stromal cells. The post-proliferative cytotrophoblastic cells fuse with the overlying syncytium leading to the formation of the trophoblastic sprouts. When villous mesenchyme invades the trophoblastic sprouts, the latter are transformed into villous sprouts. The vascularization of the villous sprouts leads to the formation of the mesenchymal villi, the most basic villous type. This process is repeated throughout pregnancy. We analyse the influence of various extracellular matrix molecules, e.g. tenascin and hyaluronic acid, on the formation of hot spots and mesenchymal villi as well as the transformation of the latter in other villous types. We present a critical survey on the data on vessel formation related to villous sprouting and morphogenesis of mesenchymal villi as well as the expression of various angiogenic factors and their receptors.