Contraction Of Blood Vessels Research Articles

Activity state of the RhoA GTPase and expression of effector molecules in placentas of women with preeclampsia (802.28)

Preeclampsia (PE) is a pregnancy‐specific multifactorial disorder characterized by hypertension and proteinuria after the 20th week of gestation. The placenta plays an important role in the origin of PE. It has been shown that RhoA proteins are involved in the development of hypertension and vasoconstriction due to contribute to the etiology of the pathogenesis of preeclampsia. These GTPases act as molecular switches interacting with effector molecules to generate cellular responses. The effector molecules of RhoA, such as ROCK, PKN and Dia, are important regulators for actin‐myosin interaction in vascular smooth muscle cells which are implicated in hypertension. Because of its importance and little background of RhoA protein and its effector molecules in placentas with PE, we determined its location in situ and activation status of RhoA, as well as their expression levels of effector molecules in cotyledon, umbilical artery and vein in placentas with PE. Immunohistochemical analysis revealed that the location of RhoA in umbilical artery and vein in pregnancies with PE is mainly in the inner layer whereas in cotyledon is in blood vessels. By pull‐down assay we observed an increase in the activation status of RhoA in all samples with PE. The expression level of effector molecules was increased in PE (Dia1, PKN and ROCK2 in the umbilical artery; PKN in umbilical vein, ROCK2 in cotyledon and ROCK1 was only detected in the cotyledon). The increase in activation of RhoA in umbilical artery and vein, suggests a possible participation of this proteins in pathological processes that generate vascular contraction in blood vessels during hypertension associated with PE. Besides effector molecules Dia1, PKN and ROCK2, ROCK1 may have an important role in the etiology of the syndrome. Acknowledgements: The authors appreciate the partial economic support from the grants of: CIC‐UMSNH (2.16 to ASM; 2.37 to SMA); CONACYT (169093 to ASM); EGOH is CONACYT fellow.

Angiotensin II Regulates Islet Microcirculation and Insulin Secretion in Mice

Angiotensin II causes potent increases in systemic and local pressure through its vasoconstrictive effect. Despite the importance of angiotensin II for local blood flow regulation, whether angiotensin II regulates the pancreatic islet microcirculation remains incompletely understood. We hypothesized that angiotensin II directly regulates the pancreatic islet microcirculation and thereby regulates insulin secretion. The aims of this study were to develop a new technique to visualize pancreatic islet hemodynamic changes in vivo and to analyze changes in islet circulation induced by angiotensin II or an angiotensin type 1 receptor blocker. Using an in vivo imaging method, we observed the pancreatic islet microcirculation. Various doses of angiotensin II or an angiotensin type 1 receptor blocker were injected intravenously, and changes in islet microcirculation were observed. Glucose-stimulated insulin secretion from the pancreas was measured from the hepatic portal vein. We identified islet microcirculation using a fluorescent dye. Angiotensin II significantly induced blood vessel contraction in the islets in a dose-dependent manner. In contrast, the angiotensin type 1 receptor blocker induced vasodilation. Glucose-stimulated insulin secretion was decreased by angiotensin II infusion. These results show that angiotensin II is involved in the regulation of pancreatic islet microcirculation and insulin secretion.

ALTERED VASCULAR MICROENVIRONMENT BY BEVACIZUMAB IN DIABETIC FIBROVASCULAR MEMBRANE

The purpose of this study was to evaluate the impact of intravitreal bevacizumab (IVB) on three cellular components (vascular endothelial cells, pericytes, and myofibroblasts) of the vascular microenvironment in fibrovascular membranes (FVMs) of patients with proliferative diabetic retinopathy. Immunohistological studies with antibodies of CD34, αSMA, and transforming growth factor-β were performed on 20 surgical specimens obtained during a pars plana vitrectomy from 8 IVB-treated eyes, whereas 12 remained untreated. Four different indexes of vascular phenotype (vascular area, vascular major axis, CD34 endothelial area, and blood vessel density) and αSMA expression in vascular and stromal components were quantitatively analyzed. The intraluminal area of blood vessels, CD34 endothelial area, and the blood vessel density in IVB-treated FVMs were significantly less than in untreated FVMs. The number of CD34 blood vessels in IVB-treated FVMs was similar to that in untreated FVMs. Intravitreal bevacizumab could not affect vascular and stromal αSMA area significantly. However, the ratio of vascular αSMA area/CD34 area was significantly higher in IVB-treated FVMs than in untreated FVMs. Transforming growth factor-β expression could be observed in the IVB-treated FVM. Intravitreal bevacizumab might primarily affect blood vessels, and the effects on pericytes and myofibroblasts might be secondary. Intravitreal bevacizumab treatment regulates vascular microenvironment by the contraction of blood vessels, the increasing pericyte ratio, and transforming growth factor-β expression in FVMs of patients with proliferative diabetic retinopathy.

Phosphorylation at Ser26 in the ATP-binding site of Ca2+/calmodulin-dependent kinase II as a mechanism for switching off the kinase activity

CaMKII (Ca2+/calmodulin-dependent kinase II) is a serine/threonine phosphotransferase that is capable of long-term retention of activity due to autophosphorylation at a specific threonine residue within each subunit of its oligomeric structure. The γ isoform of CaMKII is a significant regulator of vascular contractility. Here, we show that phosphorylation of CaMKII γ at Ser26, a residue located within the ATP-binding site, terminates the sustained activity of the enzyme. To test the physiological importance of phosphorylation at Ser26, we generated a phosphospecific Ser26 antibody and demonstrated an increase in Ser26 phosphorylation upon depolarization and contraction of blood vessels. To determine if the phosphorylation of Ser26 affects the kinase activity, we mutated Ser26 to alanine or aspartic acid. The S26D mutation mimicking the phosphorylated state of CaMKII causes a dramatic decrease in Thr287 autophosphorylation levels and greatly reduces the catalytic activity towards an exogenous substrate (autocamtide-3), whereas the S26A mutation has no effect. These data combined with molecular modelling indicate that a negative charge at Ser26 of CaMKII γ inhibits the catalytic activity of the enzyme towards its autophosphorylation site at Thr287 most probably by blocking ATP binding. We propose that Ser26 phosphorylation constitutes an important mechanism for switching off CaMKII activity.

Effect of phenylephrine and endothelium on vasomotion in rat aorta involves potassium uptake

Vasomotion is defined as the rhythmic contractions in blood vessels, consisting of two components: vasoconstriction and oscillations of the plasma membrane potential. To determine whether vasomotion is associated with changes in K(+) uptake, we measured the effect of phenylephrine (PE) and acetylcholine (ACh) on the K(+) uptake and vascular reactivity in rat aortic rings. We found that the incubation of aortic rings with 10(-7) M PE (210 ± 28 mg maximum amplitude), and 10(-6) M ACh (177 ± 6 mg maximum amplitude) produced the highest rhythmic contractions. Both 10(-7) M PE and 10(-6) M ACh significantly increased K(+) uptake in endothelium-intact aorta versus control (121 % PE, 117 % ACh). Removal of the endothelium blunted rhythmic contractions and decreased K(+) uptake in presence of vasoactive substances (88 % PE, 81 % ACh). The inhibition of nitric oxide synthase with 10(-4) M L-NNA significantly reduced the rhythmic contractions, and it was reversed in the presence of 10(-8) M sodium nitroprusside (SNP; a nitric oxide donor). Also, we found that 10(-4) M L-NNA significantly decreased the effect of 10(-7) M PE on K(+) uptake in aortic rings (104 % PE + L-NNA vs. control). The incubation of endothelium-denuded rings with 10(-8) M SNP significantly increased the K(+) uptake (116 % SNP vs. control), similar to those observed in the presence of 10(-6) M ACh. The inhibition of protein kinase G with KT-5823 blocked SNP-mediated increase in K(+) uptake. In conclusion, these data suggest that a certain range of K(+) uptake is necessary to induce the rhythmic contractions in response to vasoactive substances.

Effect of Nano-sized Carbon Black Particles on Lung and Circulatory System by Inhalation Exposure in Rats

ObjectivesWe sought to establish a novel method to generate nano-sized carbon black particles (nano-CBPs) with an average size smaller than 100 nm for examining the inhalation exposure risks of experimental rats. We also tested the effect of nano-CBPs on the pulmonary and circulatory systems.MethodsWe used chemical vapor deposition (CVD) without the addition of any additives to generate nano-CBPs with a particle size (electrical mobility diameter) of less than 100nm to examine the effects of inhalation exposure. Nano-CBPs were applied to a nose-only inhalation chamber system for studying the inhalation toxicity in rats. The effect on the lungs and circulatory system was determined according to the degree of inflammation as quantified by bronchoalveolar lavage fluid (BALF). The functional alteration of the hemostatic and vasomotor activities was measured by plasma coagulation, platelet activity, contraction and relaxation of blood vessels.ResultsNano-CBPs were generated in the range of 83.3-87.9 nm. Rats were exposed for 4 hour/day, 5 days/week for 4 weeks to 4.2 × 106, 6.2 × 105, and 1.3 × 105 particles/cm3. Exposure of nano-CBPs by inhalation resulted in minimal pulmonary inflammation and did not appear to damage the lung tissue. In addition, there was no significant effect on blood functions, such as plasma coagulation and platelet aggregation, or on vasomotor function.ConclusionWe successfully generated nano-CBPs in the range of 83.3-87.9 nm at a maximum concentration of 4.2 × 106 particles/cm3 in a nose-only inhalation chamber system. This reliable method can be useful to investigate the biological and toxicological effects of inhalation exposure to nano-CBPs on experimental rats.

Anti-hypertensive effects of probenecid via inhibition of the α-adrenergic receptor

Probenecid has long been used in the treatment of gout. Its anti-gout mechanisms consist of uric acid reuptake inhibition and the consequent facilitation of uric acid excretion. In the present study, we investigated whether probenecid could exert an anti-hypertensive effect in spontaneously hypertensive rats (SHR). The noninvasive indirect tail cuff method was employed to measure blood pressure and heart rate. The administration of probenecid (50 mg/kg, ip) induced a significant systolic blood pressure (SBP) decrease, from 167 mmHg to 141 mmHg, within 120 min. In contrast, probenecid had little effect on normotensive control Wistar Kyoto rats (WKY). The anti-hypertensive effects of probenecid are almost as potent as those of atenolol. In a further exploration of the anti-hypertensive mechanisms of probenecid, its effects on phenylephrine-induced blood vessel contraction were tested. Our results suggest that probenecid significantly inhibited the contractions of rat aorta. This effect was also observed with endothelium-removed rat aorta, suggesting that probenecid can directly interact with the α-adrenergic receptor. Moreover, probenecid inhibited the α-adrenergic-receptor-mediated activation of ERK I/II in MC3TC-E1 cells. Therefore, our results indicate that probenecid might alleviate high blood pressure in SHR via inhibition of the α-adrenergic receptor and ERK I/II.

Effect ofMucuna pruriensSeed Extract Pretreatment on the Responses of Spontaneously Beating Rat Atria and Aortic Ring toNaja sputatrix(Javan Spitting Cobra) Venom

Mucuna pruriens Linn. (velvet bean) has been used by native Nigerians as a prophylactic for snakebite. Rats pretreated with M. pruriens seed extract (MPE) have been shown to protect against the lethal and cardiovascular depressant effects of Naja sputatrix (Javan spitting cobra) venoms, and the protective effect involved immunological neutralization of the venom toxins. To investigate further the mechanism of the protective effect of MPE pretreatment against cobra venom toxicity, the actions of Naja sputatrix venom on spontaneously beating rat atria and aortic rings isolated from both MPE pretreated and untreated rats were studied. Our results showed that the MPE pretreatment conferred protection against cobra venom-induced depression of atrial contractility and atrial rate in the isolated atrial preparations, but it had no effect on the venom-induced contractile response of aortic ring preparation. These observations suggested that the protective effect of MPE pretreatment against cobra venom toxicity involves a direct protective action of MPE on the heart function, in addition to the known immunological neutralization mechanism, and that the protective effect does not involve action on blood vessel contraction. The results also suggest that M. pruriens seed may contain novel cardioprotective agent with potential therapeutic value.

P311‐null mice are hypotensive due to a systemic decrease in TGF‐beta level and activity

P311 is an 8 kDa protein highly expressed in brain and vascular smooth muscle (VSM). Telemetry and VPR tail cuff plethysmography demonstrated that p311‐null (P311 KO) mice exhibit pronounced systemic hypotension in the absence of phenotypic abnormalities. Myography and collagen gel contraction studies revealed a severe decrease in blood vessel and VSM cell contraction respectively. The hypofunctionality of the VSM contractile apparatus was confirmed by immunoblot analysis. Since we and others found that P311 is involved in TGF‐β regulation and since TGF‐β participates in blood pressure control, we determined the level and activity of TGF‐β in the VSM and blood of P311 KO mice. These studies revealed a significant downregulation in all TGF‐β1‐3 levels and activity. Treatment with exogenous recombinant TGF‐β1 or 3, but not TGF‐β2 partially rescued the defective contractile phenotype, whereas combined treatment restored normal contractility in vivo and in vitro. Our studies demonstrated that P311 controls the systemic levels and activity of TGF‐β1‐3 and thereby plays a critical role in vascular homeostasis. This work is supported by NHLBI.

Study on vasodilatation effects of total flavonoid from polygonum aviculare on blood vessel of rat in vitro

Objective To investigate the vasodilatation effects of total flavonoid from polygonum aviculare on rat thoracic aorta and its underlying mechanisms. Methods Total flavonoid from polygonum aviculare was gotten by extracted with 65% alcohol, gathered with polyamide, and eluted with 75% alcohol. The content of flavone was determined with rutoside as standard preparation. Normal rats thoracic aorta in vitro used as sample, BL-420E biological functional experiment system was utilized to record dilatation effect of total flavonoid on PE affecting pre-contracting blood vessel and the relation between dilatation effect of total flavonoid on blood vessel and calcium influx. Results Total flavonoids from polygonum aviculare can diastole contractions of thoracic aorta caused by PE. In calcium-free perfusion, gradually adding CaCl2 induced calcium influx. Clinical data showed dose-effect relation between drug and blood vessel contraction decreased in the total flavonoids from polygonum aviculare incubation rats than normal rats. Besides, total flavonoids from polygonum aviculare can obviously inhibit contraction of blood vascular circle induced by calcium releasing. Conclusion FP exerted a dose-dependent vasodilatation effect on rat isolated aorta rings by inhibiting Ca2＋ influx via L-type voltage-gated Ca2＋ channels and Ca2＋ release from sarcoplasmic reticulum, consequently decrease Ca2＋ in vascular smooth muscle cells. Key words: Polygonum aviculare; Total flavone; Hypertension; Vasodilation

Computational Modeling Predicts Novel Collagen Conformations During Mechanical Loading

Collagens contribute to the mechanical strength of many tissues throughout the body and are generally resistant to ezymatic degradation. As structural proteins, collagens often experience in vivo mechanical forces such as expansion and contraction of blood vessels and tension on tendons and ligaments. Collagen crosslinking, which enhances the strength of these structural networks, occurs during tissue development and aging. While much is known about the structure of collagen, there is a paucity of data describing how mechanical force transmitted across these crosslinks affects molecular conformation. We hypothesized that mechanical force applied perpendicular to the long axis of the collagen triple helix will result in bending and microunfolding of the triple helix structure. To test this we used Steered Molecular Dynamics to model the conformation of a collagen peptide when subjected to perpendicular forces. In silico loading predicted that the collagen peptide had minimal resistance to bending, and exhibited increased curvature with no distinct disruption of the characteristic triple helix at low forces. As force increased, we observed that the helix began to fail and underwent a microunfolding event, where a loop pulled out from the complex. This local triple helix disruption was predicted to occur below covalent bond failure strength, suggesting that alternative molecular conformations occur within the molecule as structures are loaded before the onset of structural failure. We speculate that these changes may represent nano-damage to the structure and be a mechanism for energy storage and dissipation. Furthermore, these predicted conformational changes would precede macroscopic damage mechanisms.

Hypertension: Salt restriction, sodium homeostasis, and other ions

Salt is composed of Sodium Chloride (NaCl) which in body water becomes essential electrolytes, viz., Sodium (Na⁺) and Chloride (Cl⁻) ions, including in the blood and other extracellular fluids (ECF). Na⁺ ions are necessary cations in muscle contractions and their depletion will effect all the muscles in body including smooth muscle contraction of blood vessels, a fact which is utilized in lowering the blood pressure. Na⁺ ions also hold water with them in the ECF. Na⁺ homeostasis in body is maintained by thirst (water intake), kidneys (urinary excretion) and skin (sweating). In Na⁺ withdrawal, body tries to maintain homeostasis as far as possible. However, in certain conditions (e.g., during exercise, intake of drugs and in disorders causing Syndrome of Inappropriate Anti Diuretic Hormone Secretion (SIADH), diuretics, diarrhea) coupled with moderate or severe dietary salt restriction (anorexia nervosa), hyponatremia can get precipitated. Hyponatremia is one end point in the spectrum of disorders caused by severe Na⁺ depletion whereas in moderate depletion it can cause hypohydration (or less total body water) and lower urinary volume (U v ). Moreover, salt sensitivity varies in various populations leading to different responses in relation to dietary Na⁺ intake. Diabetes and Hypertension often co-exist but Na⁺ withdrawal in salt sensitive subjects worsens diabetes though hypertension gets better and reverse occurs in salt loading. Therefore, Na⁺ or salt restriction may be non-physiological. In hypertensive subjects other alternatives to Na⁺ withdrawal could be Potassium (K⁺) and Calcium (Ca⁺²) supplementation. Further studies are required to monitor safety/side effects of salt restriction.

Comprehensive Study of Evodia rutaecarpa-induced Contraction on Blood Vascular in Vivo and in Vitro

Aim Evodiae Fructus (fruit of Evodia rutaecarpa), a blood vessel activator, has been used, with headache, migraine, shock etc., for a long history in Chinese medical practice. However, previous studies supported the vessel relaxation and the potential action on cardiac and cerebral blood circulation of vessel contraction. The present study was designed to explore it effects on contraction and the relative mechanism.

Monitoring cortical hemodynamic changes after sumatriptan injection during migraine attack by near-infrared spectroscopy

The aim of the present study is to provide effective tools for monitoring hemodynamic changes in the cortical and scalp surface during migraine attack and treatment. Using near-infrared spectroscopy system (NIRS) and laser Doppler skin blood flow (SkBF) devices in combination, we monitored changes in extra- and intra-cranial vasculature states upon sumatriptan injection during spontaneous migraine attack. We examined 4 control subjects and 4 migraine patients. Multi-channel NIRS probes were placed over the temporoparietal area bilaterally and oxygenated hemoglobin (oxy-Hb) was analyzed. Laser Doppler SkBF was simultaneously recorded to measure scalp surface blood flow changes. All patients were treated with a sumatriptan injection (3 mg), and all control subjects received a saline injection as a control for oxy-Hb/SkBF signals caused by injection pain over the monitoring period. There was a marked reduction of oxy-Hb/SkBF in all patients after sumatriptan injection, consistent with pain relief. Moreover, the changes in oxy-Hb/SkBF were significantly correlated. By contrast, saline injection did not cause any significant changes. These data suggest that sumatriptan induces blood vessel contraction at both cortical and scalp surfaces. Simultaneous oxy-Hb/SkBF recording enables real-time continuous monitoring of the effects of sumatriptan treatment in clinical situations.

Effect of 1-acyl-5,6-dimethoxy / diethoxy-2-methylthiobenzimidazoles on APD90 and isometric contraction in guinea pig atrium and aortic preparations activated by carbachol and phenylephrine

Studies have shown that 1-acyl-5,6-diethoxy-2-methylthiobenzimidazole derivatives 3-pyridyl-(1); 2-pyridyl- (2); 4-thiazolyl- (3); 4-pyridyl- (4); methyl- (5); 2-thienyl- (6) and 1-acetyl-5,6-dimethoxy-2-methylthiobenzimidazole (7) exhibit positive inotropic properties. The goal of the study was to investigate the effects of the above-mentioned compounds in restoring a decreased isometric contraction and APD90 induced by carbachol in an isolated guinea pig atrium, and to relax the aortic rings precontracted by phenylephrine. Isometric contraction and APD90 were recorded by using a force transducer and standard microelectrode technique (stimulation rate 1 Hz). Carbachol (1 μM) caused a decrease of the isometric contraction and APD90 on an overage by 63.2% and 49.6%, respectively. Compounds 1–5 used in a dose-dependent fashion (10–500 μM) abolished the action of carbachol and restored the contraction force and APD90 in the electrically driven atrium significantly; compound 2 reversed the APD90 to the baseline. Compounds 2 and 7 antagonized the contraction of aortic rings evoked by phenylephrine (10–4 M) and caused their relaxation by 24.4% and 17% at a dose of 10–4 M and by 76.2% and 72.5% at a dose of 5 × 10–4 M in groups 2 and 7, respectively. Conclusion. The results presented in the study have shown that some 1-acyl-5,6-dimethoxy / diethoxy-2-methylthiobenzimidazoles are able to abolish the effects of carbachol and phenylephrine on the AP duration and isometric contraction in guinea pig atrium and blood vessels. These data will contribute to the synthesis of targeted compounds with positive inotropic and blood-vessel relaxing characteristics among benzimidazole derivatives, which could be useful in clinical practice. Keywords: 1-acyl-2-methylthio-5,6-dimethoxy / diethoxybenzimidazoles, guinea pig atrium, blood vessel, phenylephrine hydrochloride, carbamylcholine chloride

Characterization of the Calcitonin Gene-Related Peptide Receptor Antagonist Telcagepant (MK-0974) in Human Isolated Coronary Arteries

The sensory neuropeptide calcitonin gene-related peptide (CGRP) plays a role in primary headaches, and CGRP receptor antagonists are effective in migraine treatment. CGRP is a potent vasodilator, raising the possibility that antagonism of its receptor could have cardiovascular effects. We therefore investigated the effects of the antimigraine CGRP receptor antagonist telcagepant (MK-0974) [N-[(3R,6S)-6-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)azepan-3-yl]-4-(2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridine-1-yl)piperidine-1-carboxamide] on human isolated coronary arteries. Arteries with different internal diameters were studied to assess the potential for differential effects across the coronary vascular bed. The concentration-dependent relaxation responses to human alphaCGRP were greater in distal coronary arteries (i.d. 600-1000 microm; E(max) = 83 +/- 7%) than proximal coronary arteries (i.d. 2-3 mm; E(max) = 23 +/- 9%), coronary arteries from explanted hearts (i.d. 3-5 mm; E(max) = 11 +/- 3%), and coronary arterioles (i.d. 200-300 microm; E(max) = 15 +/- 7%). Telcagepant alone did not induce contraction or relaxation of these coronary blood vessels. Pretreatment with telcagepant (10 nM to 1 microM) antagonized alphaCGRP-induced relaxation competitively in distal coronary arteries (pA(2) = 8.43 +/- 0.24) and proximal coronary arteries and coronary arterioles (1 microM telcagepant, giving pK(B) = 7.89 +/- 0.13 and 7.78 +/- 0.16, respectively). alphaCGRP significantly increased cAMP levels in distal, but not proximal, coronary arteries, and this was abolished by pretreatment with telcagepant. Immunohistochemistry revealed the expression and colocalization of the CGRP receptor elements calcitonin-like receptor and receptor activity-modifying protein 1 in the smooth muscle cells in the media layer of human coronary arteries. These findings in vitro support the cardiovascular safety of CGRP receptor antagonists and suggest that telcagepant is unlikely to induce coronary side effects under normal cardiovascular conditions.

Angiotensin II and JAK2 put on the pressure

Researchers have long known that the peptide angiotensin II is central to blood pressure control—but there is yet more to learn. A new study shows how angiotensin II cooperates with the JAK2 kinase, better known for its role in cytokine signaling, to regulate blood vessel contraction and influence blood pressure (pages 183–190).

Label-free optical control of arterial contraction

The diameters of blood vessels, especially in the brain, change dynamically over time to provide sufficient blood supply as needed. No existing technique allows noninvasive control of vascular diameter in vivo. We report that label-free irradiation with a femtosecond pulsed laser can trigger blood vessel contraction in vivo. In response to laser irradiation, cultured vascular smooth muscle cells showed a rapid increase in calcium concentration, followed by cell contraction. In a murine thinned skull window model, laser irradiation focused in the arterial vessel wall caused localized vascular contraction, followed by recovery. The nonlinear nature of the pulsed laser allowed highly specific targeting of subcortical vessels without affecting the surrounding region. We believe that femtosecond pulsed laser irradiation will become a useful experimental tool in the field of vascular biology.

Neuroprotective Effect of Visnagin on Kainic Acid-induced Neuronal Cell Death in the Mice Hippocampus

Visnagin (4-methoxy-7-methyl-5H-furo[3,2-g][1]-benzopyran-5-one), which is an active principle extracted from the fruits of Ammi visnaga, has been used as a treatment for low blood-pressure and blocked blood vessel contraction by inhibition of calcium influx into blood cells. However, the neuroprotective effect of visnagin was not clearly known until now. Thus, we investigated whether visnagin has a neuroprotective effect against kainic acid (KA)-induced neuronal cell death. In the cresyl violet staining, pre-treatment or post-treatment visnagin (100 mg/kg, p.o. or i.p.) showed a neuroprotective effect on KA (0.1 µg) toxicity. KA-induced gliosis and proinflammatory marker (IL-1β, TNF-α, IL-6, and COX-2) inductions were also suppressed by visnagin administration. These results suggest that visnagin has a neuroprotective effect in terms of suppressing KA-induced pathogenesis in the brain, and that these neuroprotective effects are associated with its anti-inflammatory effects.

Endomorphin-suppressed nitric oxide release from mice peritoneal macrophages

Endomorphins are newly discovered mu-opioid receptor selective immunocompetent opioid peptides. Endomorphin 1 is predominantly distributed in brain, while endomorphin 2 is widely allocated in the spinal cord. Lately, endomorphins have been investigated as modulators of reactive oxygen and nitrogen species. Nitric oxide is short lived radical involved in various biological processes such as regulation of blood vessel contraction, inflammation, neurotransmission and apoptosis. The aim of this work was to investigate the in vivo effects of endomorphins on nitric oxide release and NOS 2 isoenzyme upregulation in mice peritoneal macrophages additionally challenged ex vivo with lipopolysaccharide. The results showed that endomorphin 1 or endomorphin 2 in vitro did not change NO release from peritoneal mouse macrophages during a 48 h incubation period. On the other hand in vivo endomorphins had suppressive effect on NO release as well as on NOS 2 and IL-1 protein concentration. The most of suppressive effect in vivo of both endomorphins was blocked with 30 min pretreatment with mu-receptor selective antagonist beta-FNA, which proved involvement of opioid receptor pathway in suppressive effects of endomorphins.