Effects Of Urotensin Research Articles

Mechanisms underlying the urotensin II-induced proliferation of and α-smooth muscle actin expression in human dermal fibroblasts

Objective To evaluate the effects of urotensin Ⅱ on cell proliferation of and α-smooth muscle actin (α-SMA) expression in normal human dermal fibroblasts (NFs) , and to explore their regulatory mechanisms. Methods NFs were isolated from foreskin tissues and subjected to primary culture in vitro. Reverse transcription PCR and Western blot analysis were performed to measure the mRNA and protein expression of urotensin Ⅱ and its receptor, respectively. Cell counting kit-8 (CCK-8) assay was conducted to estimate the proliferation of NFs, which were treated with urotensin Ⅱ at different concentrations of 0, 10-10, 10-9, 10-8, 10-7 and 10-6 mol/L for 0, 6, 12, 24 and 48 hours separately, and then the optimal concentration and duration of urotensin Ⅱ exposure were selected to be 10-8 mol/L and 24 hours respectively. Some cultured NFs were divided into 5 groups: control group receiving no treatment, UⅡgroup treated with 10-8 mol/L urotensin Ⅱ, UⅡ+ nicardipine group treated with 10-8 mol/L urotensin Ⅱ and the calcium channel blocker nicardipine at the concentration of 10-5 mol/L, UⅡ+ PD98059 group treated with 10-8 mol/L urotensin Ⅱ and the mitogen activated protein kinase (MAPK) inhibitor PD98059 at the concentration of 10-5 mol/L, and UⅡ+ cyclosporine group treated with 10-8 mol/L urotensin Ⅱ and the calcium-dependent protein kinase (CaM PK) inhibitor cyclosporine at the concentration of 10-5 mol/L. After24-hour treatment, CCK-8 assay was conducted to evaluate the proliferation of NFs in the above groups, realtime fluorescence-based quantitative PCR and Western blot analysis were performed to determine the mRNA and protein expression of α-SMA respectively. Results Urotensin Ⅱ receptor was expressed in NFs, but urotensin Ⅱ was not. The proliferative activity of NFs significantly differed among the control group, UⅡ group, UⅡ+ nicardipine group, UⅡ+ PD98059 group and UⅡ+ cyclosporine group (the mean absorbance value at 405 nm: 1.036 ± 0.046, 1.405 ± 0.158, 1.121 ± 0.109, 1.192 ± 0.089 and 1.141 ± 0.056, respectively; F = 9.587, P < 0.01) , and the UⅡ group showed significantly higher proliferative activity of NFs compared with the control group, UⅡ + nicardipine group, UⅡ + PD98059 group and UⅡ + cyclosporine group (q = 8.263, 6.355, 4.774 and 5.912, respectively, all P < 0.05) . There were significant differences in the mRNA and protein expression of α-SMA among the 5 groups (F = 6.351, 7.045, both P < 0.01) , and the mRNA and protein expression of α-SMA was significantly higher in the UⅡ group than in the other 4 groups (all P < 0.05) . Conclusion UrotensinⅡ may induce the proliferation of and α-SMA expression in NFs through calcium channels, MAPK and CaM PK pathways. Key words: Urotensins; Fibroblasts; Cell proliferation; Actins; Cicatrix; Receptor, urotensins

Effects of UII/UT system on the expression of inflammatory signal molecules p38 MAPK and NF-κB in LPS-stimulated Kupffer cells

Objective To investigate the effects of urotensin Ⅱ/urotensin Ⅱreceptor （ UⅡ/UT） system on the expression of inflammatory signal molecules p 38 mitogen-activated protein kinase （ p38 MAPK） and nuclear factor-κB （ NF-κB ） in lipopolysaccharide （ LPS ）-stimulated Kupffer cells （ KCs ） . Methods Rat KCs were isolated and purified by means of in situ perfusion and density gradient centrifuga-tion.The isolated cells were randomly divided into six treatment groups including group 1：UⅡ（-） urantide （-）LPS（-）, group 2：UⅡ（＋）urantide（-）LPS（-）, group 3： UⅡ（-）urantide（＋）LPS（-）, group 4：UⅡ（-）urantide（-）LPS（＋）, group 5：UⅡ（＋） urantide（-） LPS（＋） and group 6：UⅡ（-）urantide（＋） LPS（＋） .Western blot assay was performed to detect p 38 MAPK/p-p38 MAPK protein and NF-κB p65 sub-unit.The DNA-binding activity of NF-κB was tested by electrophoretic mobility shift assay （EMSA）.Re-sults There was no significant difference with the expression of p 38 MAPK protein in KCs among the six groups （P〉0.05）.The expression of p65 protein and p-p38 MAPK and the DNA-binding activity of NF-κB were significantly enhanced in LPS-stimulated KCs from groups 4, 5 and 6 in comparison with those in group 1 （P〈0.01）.No significant differences with the levels of p65 protein and phosphor-p38 MAPK and the DNA-binding activity of NF-κB were observed between UⅡ/urantide-treated cells （ group 2 or group 3） and untreated cells （group 1） （all P〉0.05）, but that were decreased in group 6 than those in group 4 （all P〈0.01）.Conclusion UⅡ/UT system participated in the activation of p38 MAPK and NF-κB signaling pathways in LPS-stimulated primary Kupffer cells . Key words: UrotensinⅡ; UrotensinⅡreceptor; Urantide; Kupffer cell; p38 MAPK; NF-κB

Immunomodulatory role of urotensins in teleost Channa punctatus

The present study, for the first time in ectothermic vertebrates, reports the immunoregulatory role of urotensins I and II (UI and UII). Urotensins decreased the phagocytosis and nitrite production by splenic phagocytes. On superoxide production, UI had stimulatory while UII showed inhibitory effect. UI exerted its effect on phagocytes through corticotrophin-releasing factor (CRF) receptor as its non-specific antagonist astressin completely blocked the effect of UI on phagocytosis, nitrite release and superoxide production. Among the antagonists for specific CRF receptor 1 and 2, only CRF receptor 1 antagonist NBI 27914 abolished the effect of urotensin I. On the other hand, UII mediated its effect through urotensin receptor (UT receptor) since its antagonist urantide antagonized the effect of UII on phagocytosis, superoxide and nitrite release. These findings provide the direct evidence on physiological role of UI and UII through CRF receptor 1 and UT receptor, respectively in control of fish immune responses.

Hemodynamic-independent anti-natriuretic effect of urotensin II in spontaneously hypertensive rats

The present study aims to test the hypothesis that U-II might have a direct anti-natriuretic action in spontaneously hypertensive rats (SHR). Bolus U-II injection (15 nmol kg(-1)) caused a transient decrease in glomerular filtration rate (GFR), urine flow rate (UV), urinary sodium (UNaV) and potassium excretion (U(K)V) that corresponded with a committed decrease in mean arterial pressure (MAP) and renal blood flow (RBF) during the first 30 min. Continuous U-II infusion (0.2 nmol kg(-1)h(-1)) following a bolus U-II injection (0.3 nmol kg(-1)) caused an anti-natriuretic effect without any significant change in MAP, RBF, GFR, UV and UKV during the entire 1.5-h perfusion period in SHR. The levels of aldosterone and angiotensin II were not altered in the plasma and kidney, while plasma antidiuretic hormone decreased in response to U-II injection (15 nmol kg(-1)). Protein levels of U-II receptors (UT) were significantly increased in the kidney of 17-week-old SHR when compared with the age-matched WKY rats, while mRNA transcripts of both U-II and UT were increased in the kidney, left ventricle and thoracic aorta. In conclusion, U-II exerts a hemodynamic-independent anti-natriuretic action in adult SHR. The anti-natriuretic action of U-II in SHR is probably associated with an increased expression of the U-II-UT system in the kidney, suggesting a potential renal role of U-II in the pathogenesis of hypertension.

Enhancement of vascular smooth muscle cell migration by urotensin II

The effects of urotensin II (UII) on migration of human aortic smooth muscle cells (HASMCs) were investigated. UII (1-100 nM) significantly increased velocity of HASMC motility in a concentration-dependent manner. Stress-fiber formation and ERK (p44/p42) activity were also increased by UII. U0126 and PD 98059, MEK inhibitors, abolished the effects of UII on motility velocity and stress-fiber formation. These results suggest that UII enhances HASMC migration through activation of an ERK-dependent pathway.

Effect of Urotensin II on Cytosolic Free Calcium in Cultured Glomerular Mesangial Cells of Rats

目的 探讨尾加压素Ⅱ(UrotensinⅡ,UⅡ)对肾小球系膜细胞(GMC)内游离钙浓度的影响及其作用机制.方法以体外培养的SD乳鼠GMC为研究对象,用UⅡ刺激GMC,Fluo3/AM荧光标记细胞内游离钙离子,激光共聚焦显微技术动态测定GMC内游离钙浓度变化.结果UⅡ激发GMC内[Ca2+]i升高作用分2个时相,即瞬时峰值升高时相和缓慢持久升高时相,对峰值升高呈剂量依赖方式,在10-10mol/L～10-7mol/L范围内引起峰值升高,且随着剂量增加,幅度增大.硝苯地平和无钙缓冲液对UⅡ激发GMC内[Ca2+]i瞬时峰值升高无作用,但可完全阻止缓慢持久升高时相出现.结论UⅡ激发GMC内[Ca2+]i浓度瞬时峰值升高时相是由细胞内储存钙释放介导的,而缓慢持久升高时相是由细胞外钙流入增加引起的。

Synergistic effect of urotensin II with serotonin on vascular smooth muscle cell proliferation

Synergistic effect of urotensin II with serotonin on vascular smooth muscle cell proliferation

Synergistic effect of urotensin II with serotonin on vascular smooth muscle cell proliferation

Synergistic effect of urotensin II with serotonin on vascular smooth muscle cell proliferation

Urotensin II increases endothelin production by vascular smooth muscle cells in rats

The aim of this study was to observe the effects of urotensin II (UII) on production of endothelin (ET) in rat aortic vascular smooth muscle cells (VSMC). Cultured VSMCs incubated with various concentrations of UII were used to measure the VSMC3H-TdR incorporation, the amount of ET mRNA and ET production in VSMCs. In this work we found that UII (10−10—10−8 mol/L) promoted VSMC3H-TdR incorporation (47%—83%,P < 0.01) and increased the amount of ET mRNA by 17.1% (P < 0.05) to 112.8% (P < 0.01), respectively, in a concentration dependent manner compared with control. After 4 and 8 h incubation, 10−10-10−8 mol/L of UII elevated the ET synthesis and release in a concentration dependent manner. After 4 h incubation, the content of ET in medium was 4.9, 5.36 and 7.12 pg/mL (P < 0.01). After 8 h incubation, the ET content released from VSMCs was 12.6, 12.07 and 17.17 pg/mL (P < 0.01). In addition, it was found that BQ123, a specific ETa receptor antagonist, obviously decreased the VSMC DNA synthesis induced by UII. The results of this study showed that UII could stimulate the ET mRNA expression and ET production in VSMC. The effects of UII on VSMC DNA synthesis were partly mediated by ET autocrine pathway. It suggests that the interaction between UII and ET plays an important biological regulating role as endogenous active peptides.

Suppression of food intake induced by corticotropin-releasing factor family in neonatal chicks

Corticotropin-releasing factor (CRF), urocortin and urotensin I share amino acid sequences, and they inhibit food intake in mammals. CRF plays a potent role in decreasing food intake in avian species, but the effects of urocortin and urotensin I have not been investigated. Therefore, the effect of these three peptides on food intake in the neonatal chick was compared. In Experiment 1, birds were injected intracerebroventricularly (i.c.v.) with either 0, 0.01, 0.1 or 1 μg of urocortin following a 3-h fast, and food intake was measured for 2 h post-injection. Food intake was suppressed in a dose-dependent manner. Using a similar design in Experiment 2, the effect of urotensin I was investigated. Urotensin I appeared to suppress food intake in neonatal chicks more than urocortin did. In Experiment 3, the efficacy of CRF, urocortin and urotensin I was directly compared using one dose, 0.1 μg. The results indicated that the suppressive effect on food intake was strongest for CRF followed by urotensin I, then urocortin. These results suggest that the structure of receptors for the CRF family in chicks may be somewhat different than in mammals.

Effect of urotensin II on myocyte hypertrophy and collagen synthesis by myofibroblasts in vitro

Effect of urotensin II on myocyte hypertrophy and collagen synthesis by myofibroblasts in vitro

Effects of urotensin I and sauvagine on vascular strips of SHR and WKY

Effects of urotensin I and sauvagine on vascular strips of SHR and WKY

Ion transport in goby intestine: cellular mechanism of urotensin II stimulation

The Na- and Cl-absorbing goby posterior intestinal epithelium is composed predominantly of mitochondria-rich, tall columnar cells. Glass intracellular microelectrode recording technique was applied to absorptive cells of this relatively leaky epithelium to measure apical cell membrane potential difference (psi mc) and apical membrane fractional resistance. As determined by ion-substitution studies, absorptive cells are characterized by a large, Ba2+-inhibitable apical K conductance, which is a major factor determining psi mc and smaller Cl and Na conductances. Inhibition of the apical Na-Cl-coupled influx directly by furosemide or indirectly by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine produced hyperpolarization of psi mc, consistent with the greater apical membrane conductance to Cl than Na. The urophysial neurosecretory peptide urotensin II, which stimulates Na-Cl-coupled absorption, markedly depolarized psi mc in posterior intestinal tissues from 5% seawater-adapted gobies. This response is consistent with a stimulatory effect of urotensin II at the apical membrane carrier rather than at the basolateral Na-K-ATPase. Urotensin II is without effect on psi mc in tissues from seawater-adapted fish and somatostatin, a natural analogue of urotensin II, is without effect on tissues from fish adapted to either salinity. This specificity parallels that determined using radiotracer fluxes.

Effect of a specific and a nonspecific vasodilator on regional blood flows in experimental heart failure.

Urotensin I, a vasoactive peptide isolated from fish urophyses, has previously been demonstrated to cause specific mesenteric dilation in the dog. This mechanism of action should limit its maximal cardiovascular actions: no additional cardiovascular effects should ensure once maximal mesenteric vasodilation is achieved. Provided that the mesenteric vasodilatation does not result in decreased flow to other organs, the agent may, therefore, offer a theoretical advantage as an afterload reducing agent. In pentobarbital anesthetized dogs which were in heart failure as a result of chronic aortico -- left atrial shunt, the effects of urotensin I on cardiovascular hemodynamics were compared with the effects of a nonspecific vasodilator, sodium nitroprusside. At equidepressor doses (approximately 15% decrease in mean arterial pressure; sodium nitroprusside, 2 micrograms . kg-1 . min-1 i.v.; urotensin I, 10 mU . kg-1 . min-1 i.v.), both agents produced comparable falls in total peripheral resistance, left ventricular end diastolic pressure, and pulmonary capillary wedge pressure. Forward cardiac output was increased by both substances, although the increases were not statistically significant. Shunt flow, estimated by echocardiography, was reduced by both. In spite of the marked similarity in hemodynamic effects in this model, the two agents affected regional blood flows differently. Sodium nitroprusside did not significantly alter regional flows measured by radioactive microspheres, although calculated splanchnic, skin, and myocardial vascular resistances were reduced. In contrast, urotensin I, as in the normal dog, greatly increased mesenteric blood flow; this redistribution of cardiac output did not, however, result in underperfusion of other vital organs. These data suggest that urotensin I may be a useful agent in the reduction of afterload in heart failure, particularly since the unique mechanism of action appears to minimize the potential for adverse effects due to excessive dosage.

Effects of urotensin I on the isolated dorsal aorta of the chukar, Alectoris graeca

The effects of purified urotensin I (UI) from the Catostomus urophysis on arterial blood vessels were examined using isolated dorsal aortic strips from a bird, the chukar, Alectoris graeca. UI at concentrations greater than 1 mU/ml produced dose-dependent relaxation. The same effect was more clearly evident in aortic strips contracted by norepinephrine beforehand. The relaxation following UI was not inhibited by propranolol (10 −6 M) or atropine (10 −6 M), which markedly reduced the relaxation induced by isoproterenol or acetylcholine, respectively. The dose-dependent contractile response to norepinephrine was not significantly affected by UI, whereas it was competitively blocked by phentolamine (10 −7, 10 −6 M). Arginine vasotocin (AVT) at low concentrations (0.1 to 1.0 ng/ml) caused relaxation in 50% of the preparations and slight contraction in the other preparations; at higher concentrations AVT caused contraction in all preparations. In comparison with the response to UI, AVT-induced relaxation developed rapidly. UI at concentrations ranging from 10 to 100 mU/ml also elicited relaxation of the strips contracted by AVT. These results suggest that UI-induced aortic relaxation is not mediated through adrenergic or cholinergic receptors, and that it is unlikely that UI and AVT act by similar mechanisms.

Effects of urotensin I on the isolated rat tail artery.

Urotensin I (UI) was found to elicit dose-related relaxation responses in isolated helical strips of the rat tail artery. The responses were not prevented by adrenergic, cholingergic or histaminergic blocking agents. Competitive and non-competitive components of antagonism were observed to noradrenaline-, 5-hydroxytryptamine-, and arginine vasopressin-induced contractions. Atropine caused a direct relaxation of the isolated vascular tissues, as well as a significant potentiation of UI responses.

Pharmacological effects of urotensins. II. Renal effects of urotensin I in the rat.

Urotensin I decreased urine flow, glomerular filtration rate and renal plasma flow in intact and hypophysectomized rats. The antidiuretic effect of urotensin I differed from the that caused by AVT in that (a) the urine conductivity was not usually increased by the former, and (b) the rates of excretion of Na and K were different. The use of hypophysectomized rats and of Na-thioglycollate-treated urotensin I preparations indicated that the antidiuretic effect of urotensin I was not due to the release of endogenous ADH, nor was it caused by presence of AVT in the urotensin I samples.

Effects and assay of urotensin I on the perfused hind limb of the rat

Urotensin I, the long-acting mammalian hypotensive principle obtainable from fish urophyses, elicited a marked, dose-dependent decrease in perfusion pressure in the isolated rat hind limb. The sensitivity of the preparation to urotensin I was increased by 2 orders of magnitude by including noradrenaline (5 × 10 −7-1.5 × 10 −6 g/ml) in the perfusion fluid and perfusing at 1.3–2.5 ml/min at 22–24°. Threshold doses of urotensin I were in the range of fractions of mU (<1 μg acetone dried urophysial powder). The effect of urotensin I was not modified by atropine, mecamylamine, propranolol or diphenhydramine nor by acetylcholine or histamine, or both, when present in urotensin samples. Response to urotensin II could not be detected on the hind limb preparation. Use of the hind limb preparation for assays of urotensin I showed a good dose-response resationship and a high degree of precision.