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European journal of pharmacology [journal]
- Mephedrone: Public health risk, mechanisms of action, and behavioral effects. [JOURNAL ARTICLE]
- Eur J Pharmacol 2013 Jun 10.
The recent shortage of 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy) has led to an increased demand for alternative amphetamine-like drugs such as the synthetic cathinone, 4-methylmethcathinone (mephedrone). Despite the re-classification of mephedrone as a Class B restricted substance by the United Kingdom and restrictive legislation by the United States, international policy regarding mephedrone control is still developing and interest in synthetic amphetamine-like drugs could drive the development of future mephedrone analogues. Currently, there is little literature investigating the mechanism of action and long-term effects of mephedrone. As such, we reviewed the current understanding of amphetamines, cathinones, and cocaine emphasizing the potentially translational aspects to mephedrone, as well as contrasting with the work that has been done specifically on mephedrone in order to present the current state of understanding of mephedrone in terms of its risks, mechanisms, and behavioral effects. Emerging research suggests that while there are structural and behavioral similarities of mephedrone with amphetamine-like compounds, it appears that serotonergic signaling may mediate more of mephedrone's effects unlike the more dopaminergic dependent effects observed in traditional amphetamine-like compounds. As new designer drugs are produced, current and continuing research on mephedrone and other synthetic cathinones should help inform policymakers' decisions regarding the regulation of novel 'legal highs.'
- Rhododendrin ameliorates skin inflammation through inhibition of NF-κB, MAPK, and PI3K/Akt signaling. [JOURNAL ARTICLE]
- Eur J Pharmacol 2013 Jun 10.
A wide range of active compounds isolated from nature are used in clinical applications and as a source of lead compounds for drug development. Rhododendron brachycarpum has been used as an oriental herbal medicine for skin inflammatory diseases. In this study, we isolated rhododendrin from Rhododendron brachycarpum leaves and investigated its molecular mechanisms for anti-inflammatory effect. Rhododendrin showed intracellular reactive oxygen species scavenging activity and suppressed nuclear translocation of nuclear factor-κB (NF-κB) by inhibiting phosphorylation of NF-κB, inhibitor of NF-κB(IκBα), and IκBα kinase(IKKα/β). Furthermore, rhododendrin inhibited mitogen-activated protein kinases (MAPKs), including ERK1/2, p38, and decreased c-Jun N-terminal kinase (JNK) and phosphoinositide 3-kinase (PI3K)/Akt signaling. As a result, rhododendrin reduced expression of pro-inflammatory mediators, such as cyclooxygenase-2 (COX-2), intracellular adhesion molecule-1 (ICAM-1), interleukin-1α (IL-1α), IL-1β, IL-6, IL-8, tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), chemokine (C-X-C) motif ligand 1 (CXCL1), and chemokine (C-C motif) ligand 17 (CCL17) in TNF-α/IFN-γ-stimulated keratinocytes. Notably, we demonstrated that topically applied rhododendrin alleviated skin inflammation in trinitrochlorobenzene (TNCB)-treated mouse ear skins. Collectively, these results indicate that rhododendrin is a biologically active compound that exhibits anti-inflammatory activity and is a promising candidate molecule to treat inflammatory skin diseases, such as psoriasis.
- SMND-309, a novel derivative of Salvianolic acid B, protects rat brains ischemia and reperfusion injury by targeting the JAK2/STAT3 pathway. [JOURNAL ARTICLE]
- Eur J Pharmacol 2013 Jun 10.
SMND-309 is a novel derivative of salvianolic acid B, and has shown protective effects against rat cortical neuron damage in vitro and in vivo. However the molecular mechanisms through which SMND-309 affords this protection are unclear. The present study aimed to investigatethe mechanisms associated with the protective activities of SMND-309 in a cerebral ischemia and reperfusion injury rat model. In this study, we used AG490, a specific inhibitor of the signaling pathway involving the Janus Kinase 2 (JAK2)/Signal Transducers and Activators of Transcription 3 (STAT3) signaling molecules and suramin, a potent inhibitor of vascular endothelial growth factor (VEGF), to investigate the mechanisms of SMND-309. The cerebral ischemia and reperfusion injury model was induced by performing middle cerebral artery occlusion (MCAO) in the rats. SMND-309 mitigated the effects of ischemia and reperfusion injury on brain by decreasing the infract volume, improving neurological function, increasing the survival of neurons and promoting angiogenesis by increasing the levels of erythropoietin (EPO), erythropoietin receptor (EPOR), phosphorylated JAK2 (P-JAK2), phosphorylated STAT3 (P-STAT3), VEGF and VEGF receptor 2 (Flk-1) in the brain. Our results suggest that SMND-309 provides significant neuroprotective effects against cerebral ischemia and reperfusion injury. The mechanisms of this protection may be attributed to the increased VEGF expression occurring from the JAK2/STAT3 pathway, activated by the increased EPO/EPOR expression in the brain.
- Icariin induces osteoblast proliferation, differentiation and mineralization through estrogen receptor-mediated ERK and JNK signal activation. [JOURNAL ARTICLE]
- Eur J Pharmacol 2013 Jun 10.
Icariin, the main active flavonoid glucoside isolated from Herba epimedii (HEF), is an anabolic agent in bone that has been reported to prevent bone loss in ovariectomized rats and postmenopausal women. However, the molecular mechanism for this anabolic action of Icariin remain largely unknown. Here, we found that Icariin could promote MC3T3-E1 osteoblastic cell proliferation and reduce cell apoptosis, associated with increased mRNA levels of positive regulators of cell cycle gene Cyclin E and proliferating cell nuclear antigen (PCNA), decreaed mRNA level of negative regulator gene, Cyclin-dependent kinase 4 inhibitor B (Cdkn2B), and reduced caspase-3 activity. Icariin also enhanced MC3T3-E1 cell differentiation and mineralization demonstrated by increased the expression of differentiation markers, alkaline phosphatase (ALP) and collagen type I (Col I), and bone nodule formation via Alizarin red S staining. To characterize the underlying mechanisms, we examined the effect of Icariin on mitogen-activated protein kinase (MAPK) signaling. Icariin treatment rapidly induced extracellular signal-regulated kinase (ERK) and c-Jun N terminal kinase (JNK) activation but showed no effect on activation of p38 kinase. Furthermore, Icariin- mediated effects on osteoblasts were dramatically attenuated by treatment with specific inhibitors of MAPKs, U0126 (ERK inhibitor) and SP600125 (JNK inhibitor). Interestingly, treatment of osteoblasts with estrogen receptor antagonist ICI182780 attenuated Icariin- mediated effect of proliferation and mineralization, associated with suppression of ERK and JNK phosphorylation. These observations provide a potential mechanism of anabolic actions of Icariin involving ERK and JNK pathway by estrogen receptor.
- The role of α2-adrenoceptors in the anti-convulsant effects of cannabinoids on pentylenetetrazole-induced seizure threshold in mice. [JOURNAL ARTICLE]
- Eur J Pharmacol 2013 Jun 8.
Cannabinoid system plays a pivotal role in the seizure threshold modulation which is mainly mediated through activation of the cannabinoid CB1 receptor. There is also several evidence of interaction between cannabinoid system and α2-adrenoceptors in different paradigms. Using model of clonic seizure induced by intravenous pentylenetetrazole (PTZ) in male mice, we investigated whether α2-adrenoceptors is involved in the effects of cannabinoids on the seizure threshold. Injection of the selective cannabinoid CB1 agonist ACEA (2mg/kg) significantly (P<0.01) increased the seizure threshold which was prevented by pretreatment with the selective CB1 antagonist AM251 (1mg/kg, i.p.). The highest doses of clonidine, a α2 receptor agonist, (1 and 5mg/kg) showed anticonvulsant effects while yohimbine, a α2 receptor antagonist, (0.01, 0.1, 1, and 10mg/kg) did not induce any significant effect on PTZ seizure threshold. Pretreatment with clonidine (0.1 and 0.5mg/kg) significantly reversed the anticonvulsant effect of ACEA (2mg/kg). Yohimbine (0.1, 1, and 10mg/kg) pretreatment of mice enhanced the clonic seizure threshold of ACEA (1mg/kg), significantly. Combination of non-effective doses of AM251 (0.1mg/kg) and clonidine (0.01mg/kg) showed additive effect in blocking the anticonvulsant effect of ACEA (2mg/kg). In conclusion, our findings demonstrated that α2-adrenoceptors could be involved in the anticonvulsant properties of the specific cannabinoid CB1 agonist ACEA, suggesting that CB1 cannabinoid and α2 receptors have functional interactions in modulation of clonic seizure threshold.
- 2-Aryl- and 2-amido-benzothiazoles as multifunctional vasodilators on rat artery preparations. [JOURNAL ARTICLE]
- Eur J Pharmacol 2013 Jun 7.
The neuroprotective agent riluzole [2-amino-6-(trifluoromethoxy)benzothiazole] has been shown to antagonize neuronal high-voltage activated Ca(2+) currents. In the search for novel scaffolds leading to potential antihypertensive agents, a series of 2-aryl- and 2-amido-benzothiazoles (HUP) were assessed for their vasorelaxing property on rat aorta rings and for their L-type Ba(2+) currents [IBa(L)] blocking activity on single myocytes isolated from the rat tail artery. HUP5 and HUP30, the most potent of the series, inhibited phenylephrine-induced contraction with IC50 values in the range 3-6µM. The presence of endothelium did not modify their spasmolytic activity. Both HUP5 and HUP30 increased tissue levels of cGMP and shifted to the left the concentration-response curve to sodium nitroprusside. In rings precontracted by phenylephrine, tetraethylammonium or 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ) shifted to the right the concentration-relaxation curves of HUP5 and HUP30. The antispasmodic effect of HUP5 and HUP30 was more marked on rings stimulated with 25/30mM than with 60mM K(+). HUP5 and HUP30 antagonized both extracellular Ca(2+) influx and Ca(2+) mobilization from intracellular stores in response to phenylephrine: this effect was not modified by the presence of ODQ. IBa(L) was partly inhibited by HUP5 and blocked by HUP30 in a concentration-dependent as well as ODQ-independent manner. In conclusion, HUP5 and HUP30 are vasorelaxing agents that stimulate soluble guanylyl cyclase, activate K(+) channels, and block extracellular Ca(2+) influx. The present benzothiazole derivatives form a novel class of multifunctional vasodilators which may give rise to effective antihypertensive agents.
- Low nanomolar thapsigargin inhibits the replication of vascular smooth muscle cells through reversible endoplasmic reticular stress. [JOURNAL ARTICLE]
- Eur J Pharmacol 2013 Jun 7.
Thapsigargin (TG), an inhibitor of Ca(2+) ATPase pumps in the endoplasmic reticulum (ER), inhibits replication of human vascular smooth muscle cell (hVSMC) at low nM concentrations. TG blocks replication of other cell types through promotion of ER stress (ERS). In order to determine whether ERS may mediate the cytostatic effect of TG in hVSMCs, the effect of TG on ERS in hVSMCs was studied by assessing markers of ERS: Immunoglobulin Heavy Chain Binding Protein (BiP), growth inhibitory transcription factor, GADD153, phosphorlylated eukaryotic initiation factor 2α (p-eIF2α) and phosphorlylated protein kinase R (p-PKR). hVSMCs derived from saphenous veins were rendered quiescent with serum-free medium for 96h incubated with 10nM TG at 37°C for 24h, then washed free of TG and incubated with 10% foetal calf serum (FCS) for a further 24h. At selected times, BiP, GADD153, p-eIF2α, p-PKR and cyclin D1 expression was assessed. TG promoted a marked increase in BiP and GADD153, but suppressed cyclin D1 mRNA and protein expression. Under serum-free conditions p-eIF2α and p-PKR expression was not enhanced by TG. 15-24h After removal of TG all these factors returned to levels seen in control cells. These data demonstrate that the inhibitory effect of 10nM TG on hVSMC replication is mediated through induction of ERS and associated factors that cessate replication and is reversible. These observations have implications in the aetiology and treatment of diseases that include atherogenesis, vein graft failure and restenosis.
- Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors functional regulation during enhanced liver cell proliferation by GABA and 5-HT chitosan nanoparticles treatment. [JOURNAL ARTICLE]
- Eur J Pharmacol 2013 Jun 6.
Liver is one of the major organs in vertebrates and hepatocytes are damaged by many factors. The liver cell maintenance and multiplication after injury and treatment gained immense interest. The present study investigated the role of Gamma aminobutyric acid (GABA) and serotonin or 5-hydroxytryptamine (5-HT) coupled with chitosan nanoparticles in the functional regulation of Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors mediated cell signaling mechanisms, extend of DNA methylation and superoxide dismutase activity during enhanced liver cell proliferation. Liver injury was achieved by partial hepatectomy of male Wistar rats and the GABA and 5-HT chitosan nanoparticles treatments were given intraperitoneally. The experimental groups were sham operated control (C), partially hepatectomised rats with no treatment (PHNT), partially hepatectomised rats with GABA chitosan nanoparticle (GCNP), 5-HT chitosan nanoparticle (SCNP) and a combination of GABA and 5-HT chitosan nanoparticle (GSCNP) treatments. In GABA and 5-HT chitosan nanoparticle treated group there was a significant decrease (P<0.001) in the receptor expression of Gamma aminobutyric acid B and a significant increase (P<0.001) in the receptor expression of 5-hydroxy tryptamine 2A when compared to PHNT. The cyclic adenosine monophosphate content and its regulatory protein, presence of methylated DNA and superoxide dismutase activity were decreased in GCNP, SCNP and GSCNP when compared to PHNT. The Gamma aminobutyric acid B and 5-hydroxy tryptamine 2A receptors coupled signaling elements played an important role in GABA and 5-HT chitosan nanoparticles induced liver cell proliferation which has therapeutic significance in liver disease management.
- Bafetinib inhibits functional responses of human eosinophils in vitro. [JOURNAL ARTICLE]
- Eur J Pharmacol 2013 Jun 6.
Eosinophils play a prominent role in the process of allergic inflammation. Non-receptor associated Lyn tyrosine kinases generate key initial signals in eosinophils. Bafetinib, a specific Abl/Lyn tyrosine kinase inhibitor has shown a potent antiproliferative activity in leukemic cells, but its effects on eosinophils have not been reported. Therefore, we studied the effects of bafetinib on functional and mechanistic responses of isolated human eosinophils. Bafetinib was more potent than non-specific tyrosin kinase comparators genistein and tyrphostin inhibiting superoxide anion triggered by N-formyl-Met-Leu-Phe (fMLF; 100nM) (-log IC50=7.25±0.04M; 6.1±0.04M; and 6.55±0.03M, respectively). Bafetinib, genistein and tyrphostin did not modify the [Ca(2+)]i responses to fMLF. Bafetinib inhibited the release of EPO induced by fMLF with higher potency than genistein and tyrphostin (-log IC50=7.24±0.09M; 5.36±0.28M; and 5.37±0.19M, respectively), and nearly suppressed LTC4, ECP and chemotaxis. Bafetinib, genistein and tyrphostin did not change constitutive apoptosis. However bafetinib inhibited the ability of granulocyte-monocyte colony-stimulating factor to prevent apoptosis. The activation of Lyn tyrosine kinase, p-ERK1/2 and p-38 induced by fMLF was suppressed by bafetinib and attenuated by genistein and tyrphostin. In conclusion, bafetinib inhibits oxidative burst and generation of inflammatory mediators, and reverses the eosinophil survival. Therefore, future anti-allergic therapies based on bafetinib, could help to suppress excessive inflammatory response of eosinophils at inflammatory sites.
- Anti-inflammatory glucocorticoids: Changing concepts. [JOURNAL ARTICLE]
- Eur J Pharmacol 2013 Jun 7.
Despite being the most effective anti-inflammatory treatment for chronic inflammatory diseases, the mechanisms by which glucocorticoids (corticosteroids) effect repression of inflammatory gene expression remain incompletely understood. Direct interaction of the glucocorticoid receptor (NR3C1) with inflammatory transcription factors to repress transcriptional activity, i.e. transrepression, represents one mechanism of action. However, transcriptional activation, or transactivation, by NR3C1 also represents an important mechanism of glucocorticoid action. Glucocorticoids rapidly and profoundly increase expression of multiple genes, many with properties consistent with the repression of inflammatory gene expression. For example: the dual specificity phosphatase, DUSP1, reduces activation of mitogen-activated protein kinases; glucocorticoid-induced leucine zipper (TSC22D3) represses nuclear factor-κB (NF-κB) and activator protein 1 (AP-1) transcriptional responses; inhibitor of κBα (NFKBIA) inhibits NF-κB; tristraprolin (ZFP36) destabilises and translationally represses inflammatory mRNAs; CDKN1C, a cell cycle regulator, may attenuate JUN N-terminal kinase signalling; and regulator of G-protein signalling 2 (RGS2), by reducing signalling from Gαq-linked G protein-coupled receptors (GPCRs), is bronchoprotective. While glucocorticoid-dependent transrepression can co-exist with transactivation, transactivation may account for the greatest level and most potent repression of inflammatory genes. Equally, NR3C1 transactivation is enhanced by β2-adrenoceptor agonists and may explain the enhanced clinical efficacy of β2-adrenoceptor/glucocorticoid combination therapies in asthma and chronic obstructive pulmonary disease. Finally, NR3C1 transactivation is reduced by inflammatory stimuli, including respiratory syncytial virus and human rhinovirus. This provides an explanation for glucocorticoid resistance. Continuing efforts to understand roles for glucocorticoid-dependent transactivation will provide opportunities to improve glucocorticoid therapies.