Ca2+ signaling in human fetoplacental vasculature: effect of CGRP on umbilical vein smooth muscle cytosolic Ca2+ concentration

DNA Methylation Pattern of CALCA and CALCB in Extremely Premature Infants with Monochorionic Triplets after Single-Embryo Transfer

Compared with full-term peers, premature infants are more likely to suffer from neonatal diseases and death. Variations in DNA methylation may affect these pathological processes. Calcitonin gene-related peptide (CGRP) plays a complex and diversified role in reproduction and chronic inflammation, and participates in the functional maintenance of vascular adaptation and trophoblast cells during pregnancy. Here, premature live births with single-chorionic triple embryos after single-embryo transfer were used as research objects, while full-term infants with double embryos and double-chorionic twins were used as controls. DNA was extracted from umbilical cord tissues for pyrosequencing to detect the methylation level of CpG island in CGRP promoter region. The average values of CGRP methylation in the umbilical cord tissues of very premature fetuses were higher than that of normal controls obtained from the databases. Immunofluorescence results showed that the expression of αCGRP was decreased in the blood vessel wall of the umbilical cord of monozygotic triplets, especially in death cases, while the βCGRP had a compensatory expression. In conclusion, our findings suggest that hypermethylation of CGRP might be considered as an important cause of serious neonatal morbidities.

Perivascular innervation: a multiplicity of roles in vasomotor control and myoendothelial signaling

The control of vascular resistance and tissue perfusion reflect coordinated changes in the diameter of feed arteries and the arteriolar networks they supply. Against a background of myogenic tone and metabolic demand, vasoactive signals originating from perivascular sympathetic and sensory nerves are integrated with endothelium-derived signals to produce vasodilation or vasoconstriction. PVNs release adrenergic, cholinergic, peptidergic, purinergic, and nitrergic neurotransmitters that lead to SMC contraction or relaxation via their actions on SMCs, ECs, or other PVNs. ECs release autacoids that can have opposing actions on SMCs. Respective cell layers are connected directly to each other through GJs at discrete sites via MEJs projecting through holes in the IEL. Whereas studies of intercellular communication in the vascular wall have centered on endothelium-derived signals that govern SMC relaxation, attention has increasingly focused on signaling from SMCs to ECs. Thus, via MEJs, neurotransmission from PVNs can evoke distinct responses from ECs subsequent to acting on SMCs. To integrate this emerging area of investigation in light of vasomotor control, the present review synthesizes current understanding of signaling events that originate within SMCs in response to perivascular neurotransmission in light of EC feedback. Although often ignored in studies of the resistance vasculature, PVNs are integral to blood flow control and can provide a physiological stimulus for myoendothelial communication. Greater understanding of these underlying signaling events and how they may be affected by aging and disease will provide new approaches for selective therapeutic interventions.

Hemodynamic correlates of low umbilical cord vitamin D and ionized calcium

Vitamin D deficiency and hypocalcemia are associated with gestational hypertension. Therefore, we hypothesized that umbilical cord [Ca(2+)] and [vitamin D] are correlated with perinatal blood pressures. Mothers and newborns comprised vitamin D sufficient (vitamin D ≥ 50 nM, range 52-111 nM, n = 14), and vitamin D deficient groups (vitamin D < 50 nM, range 13-49 nM, n = 29). Cord [Ca²⁺] was negatively correlated with maternal systolic pressure (SBP) (r = -0.56, p < 0.01) and positively correlated with neonatal SBP (r = +0.55, p < 0.01) in the vitamin D deficient group. We conclude that low umbilical cord [vitamin D] and [Ca²⁺] may predispose mothers to higher and newborns to lower blood pressures.

Nocistatin inhibits pregnant rat uterine contractions in vitro: roles of calcitonin gene-related peptide and calcium-dependent potassium channel

The endogenous neuropeptide nociceptin/orphanin FQ, translated from the prepronociceptin gene, exerts a contraction-inhibitory effect on the rat uterus. As nocistatin has been reported to cause functional antagonism of the pro-nociceptive effects of nociceptin, we set out to investigate its effects on the pregnant rat uterus and to elucidate its signalling pathway. The expression of prepronociceptin mRNA in the uterus and nocistatin levels in the uterus and the plasma were confirmed by RT-PCR and radioimmunoassay. The uterine levels of prepronociceptin mRNA and nocistatin were significantly increased by the last day of pregnancy, while the plasma nocistatin levels remained unchanged. In the isolated organ bath studies nocistatin inhibited the prostaglandin- and the KCl-evoked contractions in the uterus dose-dependently. This latter effect was decreased by preincubation with capsaicin. Incubation with calcitonin gene-related peptide after capsaicin treatment caused an elevation in the contraction-inhibitory effect of nocistatin. The effect of nocistatin was also decreased by the Ca(2+)-dependent K(+) channel inhibitor paxilline, against spontaneous uterine contractions. Nociceptin potentiated the action of nocistatin. Naloxone decreased the effect of nocistatin administered either alone or in combination with nociceptin. In Ca(2+)-poor environment, this effect of naloxone was suspended. Enzyme immunoassay for the uterine intracellular cAMP levels partially confirmed the results of in vitro contractility studies. We conclude that nocistatin, generated locally in the uterus, exerts an inhibitory effect, the mechanism being mediated in part by Ca(2+)-dependent K(+) channels, the elevation of cAMP levels and sensory neuropeptides.

Portal hypertensive response to kinin

Portal hypertension is the most common complication of chronic liver diseases, such as cirrhosis. The increased intrahepatic vascular resistance seen in hepatic disease is due to changes in cellular architecture and active contraction of stellate cells. In this article, we review the historical aspects of the kallikrein-kinin system, the role of bradykinin in the development of disease, and our main findings regarding the role of this nonapeptide in normal and experimental models of hepatic injury using the isolated rat liver perfusion model (mono and bivascular) and isolated liver cells. We demonstrated that: 1) the increase in intrahepatic vascular resistance induced by bradykinin is mediated by B2 receptors, involving sinusoidal endothelial and stellate cells, and is preserved in the presence of inflammation, fibrosis, and cirrhosis; 2) the hepatic arterial hypertensive response to bradykinin is calcium-independent and mediated by eicosanoids; 3) bradykinin does not have vasodilating effect on the pre-constricted perfused rat liver; and, 4) after exertion of its hypertensive effect, bradykinin is degraded by angiotensin converting enzyme. In conclusion, the hypertensive response to BK is mediated by the B2 receptor in normal and pathological situations. The B1 receptor is expressed more strongly in regenerating and cirrhotic livers, and its role is currently under investigation.

Calcitonin gene-related peptide (CGRP) triggers Ca2+ responses in cultured astrocytes and in Bergmann glial cells from cerebellar slices

The neuropeptide calcitonin gene-related peptide (CGRP) is transiently expressed in cerebellar climbing fibers during development while its receptor is mainly expressed in astrocytes, in particular Bergmann glial cells. Here, we analyzed the effects of CGRP on astrocytic calcium signaling. Mouse cultured astrocytes from cerebellar or cerebral cortex as well as Bergmann glial cells from acutely isolated cerebellar slices were loaded with the Ca(2+) sensor Fura-2. CGRP triggered transient increases in intracellular Ca(2+) in astrocytes in culture as well as in acute slices. Responses were observed in the concentration range of 1 nm to 1 mm, in both the cell body and its processes. The calcium transients were dependent on release from intracellular stores as they were blocked by thapsigargin but not by the absence of extracellular calcium. In addition, after CGRP application a further delayed transient increase in calcium activity could be observed. Finally, cerebellar astrocytes from neonatal mice expressed receptor component protein, a component of the CGRP receptor, as revealed by immunofluorescence and confocal microscopy. It is thus proposed that the CGRP-containing afferent fibers in the cerebellum (the climbing fibers) modulate calcium in astrocytes by releasing the neuropeptide during development and hence possibly influence the differentiation of Purkinje cells.