European journal of pharmacology [journal]
- Angiotensin-converting enzyme inhibitors modulate kynurenic acid production in rat brain cortex in vitro. [JOURNAL ARTICLE]
- Eur J Pharmacol 2016 Jul 13.
It is well established that the renin-angiotensin system (RAS) is present in the brain and that glutamate activates the brain centers responsible for blood pressure control. An antagonist of glutamate, kynurenic acid (KYNA) was shown to decrease blood pressure after intracerebral administration. KYNA is an endogenous metabolite of tryptophan produced from the breakdown of kynurenine by kynurenine aminotransferases (KAT), mainly within astrocytes. The purpose of this study was to evaluate the influence of three angiotensin-converting enzyme inhibitors (lisinopril, perindopril and ramipril) on KYNA production and KAT activity in the rat brain cortex in vitro. The effect of the angiotensin-converting enzyme inhibitors on KYNA production was examined on rat brain cortical slices incubated for 2h in the presence of l-kynurenine and the angiotensin-converting enzyme inhibitors. To analyze KAT I and KAT II activity, brain cortical homogenates were incubated for 2h with l-kynurenine and the tested drugs. KYNA was separated by HPLC and quantified fluorometrically. Among the examined angiotensin-converting enzyme inhibitors, lisinopril increased KYNA production, perindopril was ineffective, and ramipril decreased KYNA synthesis in rat brain cortical slices. Lisinopril increased KAT I activity and perindopril did not affect it. However, ramipril lowered KAT I activity in rat brain cortex in vitro. Neither lisinopril nor perindopril affected KAT II activity, but ramipril decreased KAT II activity in the rat brain cortex in vitro. Our study reveals that angiotensin-converting enzyme inhibitors show various influences on KYNA production in rat brain cortical slices and activity of KATs.
- In vitro contractile effects of agents used in the clinical management of postpartum haemorrhage. [JOURNAL ARTICLE]
- Eur J Pharmacol 2016 Jul 13.
Uterine atony is a major cause of postpartum haemorrhage and maternal mortality. However, the comparative pharmacology of agents used to treat this condition is poorly understood. This study evaluates, using human pregnant myometrium in vitro, a range of contractile parameters for agents used in the clinical treatment of atonic postpartum haemorrhage. The effects of oxytocin, carbetocin, ergometrine, carboprost, syntometrine and misoprostol were investigated in 146 myometrial strips from 19 donors. The potency and maximal response values were obtained, and compared, using both maximal amplitude and mean contractile force as indices of contraction. Single, EC50 concentrations of the agents were administered and both force and contraction peak parameters were compared during a 15-min exposure. Differences were considered significant when P<0.05. There were no significant differences in the peak amplitude of response between agents, except for misoprostol, which was inactive. There was a wide difference in potencies using both measures of contractility, with oxytocin and carbetocin being the most potent. The most important difference between the agents was in their ability to increase the mean contractile force, with oxytocin superior to all agents except syntometrine. In single dose experiments, mean contractile force was the parameter that separated the agents. In this respect, oxytocin was not statistically different from carboprost or syntometrine, but was superior to all other agents. These findings support a clear role for oxytocin as the first line agent for treatment of postpartum haemorrhage and raise doubts about the potential clinical usefulness of misoprostol.
- Activation of islet 5-HT4 receptor regulates glycemic control through promoting insulin secretion. [JOURNAL ARTICLE]
- Eur J Pharmacol 2016 Jul 13.
Mosapride, a gastrointestinal prokinetic drug, is an agonist of 5-hydroxytryptamine (5-HT) receptor 4 that also reduces blood glucose. Whether 5-HT4 receptor is distributed in pancreatic islets and whether mosapride can directly stimulate insulin secretion is unclear. In the present study, the protein expression and cellular location of 5-HT4 receptor in pancreas was detected through western blotting and immunofluorescence. The acute effects of 5-HT4 receptor agonists, mosapride and prucalopride, on insulin secretion were investigated in vivo and in vitro in normal and alloxan-induced diabetes rats. The results indicated that 5-HT4 receptor immunoreactivity was co-existed in the islets insulin-immunoreactive cells of rat, mouse, pig and human. However the immunoreactive cells of insulin and 5-HT4 receptor and the protein expression of 5-HT4 receptor were significantly decreased in the pancreas of alloxan-induced diabetes rats. In normal rats, mosapride and prucalopride decreased blood glucose and increased insulin secretion during glucose tolerance test, in association with an increase in glucose-stimulated insulin secretion, which was abolished by the 5-HT4 receptor antagonist GR113808. In diabetes rats, mosapride and prucalopride failed to improve blood glucose and insulin levels in the group of 180mg/kg alloxan, but increased glucose-stimulated insulin secretion in the group of 120mg/kg alloxan in vitro. We conclude that 5-HT4 receptor is distributed in the islet β cell. Activation of 5-HT4 receptor is able to stimulate insulin secretion directly, thereby reduce blood glucose. The study provides important experimental evidences for the 5-HT4 receptor regulating insulin secretion and acting as a potential drug target in diabetes treatment.
- Telmisartan-mediated metabolic profile conferred brain protection in diabetic hypertensive rats as evidenced by magnetic resonance imaging, behavioral studies and histology. [JOURNAL ARTICLE]
- Eur J Pharmacol 2016 Jul 11.
Type 2 diabetes and hypertension are associated with cognitive dysfunction that includes pathological changes in brain tissue. It was speculated that the beneficial hypotensive effect of telmisartan, an angiotensin receptor 1 blocker, and its unique hypoglycemic effect due to its PPARγ-activation, could ameliorate the pathological changes in the brain that accompany these diseases. We examined the effect of telmisartan on brain changes in magnetic resonance imaging (MRI) T2-weighted scans, and behavioral and histological findings in the Cohen-Rosenthal Diabetic Hypertensive (CRDH) rat. Baseline and post-treatment values with telmisartan/vehicle (3 months) of blood pressure, blood glucose levels, behavioral tests, brain MRI scanning and immunohistological staining were obtained. Telmisartan significantly lowered blood pressure and blood glucose levels; induced consistent T2 reduction in specific gray and white regions including hippocampus, corpus callosum, amygdala and cortical regions; and significantly improved performance on behavioral tasks. Immunohistological analysis of the brain revealed significant amelioration of diabetes/hypertension-induced changes in white matter regions and microglia, evidenced by preserved myelin (LBF marker), and improved microglial neuronal markers GFAP, GAP43 and Iba1 expression. In conclusion, the behavioral performance, longitudinal MRI study and histology staining revealed the protective effects of telmisartan on brain microstructure and cognitive function.
- Enhanced colon cancer chemoprevention of curcumin by nanoencapsulation with whey protein. [JOURNAL ARTICLE]
- Eur J Pharmacol 2016 Jul 9.
To improve bioavailability and enhance colon cancer prevention ability of curcumin, whey protein was used to nanoencapsulate at three different ratios such as 70:30, 50:50 and 35:65 for the first time. The drug loading, entrapment efficiency and structural changes of curcumin was confirmed by quantitative NMR spectroscopy. The nanoparticles prepared using the three ratios had an average diameters of 236.5±8.8, 212±3.4, and 187±11.4nm, as well as zeta (ζ) potentials of -13.1, -9.26, and -4.63 mV, respectively, at pH 7.0. The cytotoxicity assay was performed for human colon and prostate cancer (SW480 and LNCap) by MTT assay and results showed significantly higher cytotoxicity of nanoencapsulated curcumin (NEC) (equivalent to 30.91, 20.70 and 16.86µM of NEC-1, 2 and 3 respectively), as compared to plain curcumin at 50µM after 72h of treatment. Cytotoxicity was also confirmed by microscopy of treated cells stained with acridine orange and propidium iodide. The cells treated with 50µM of curcumin, 30.91µM (NEC-1), 20.70µM (NEC-2) and 16.86µM (NEC-3) showed enhanced activation of p53 and elevated bax/Bcl2 expression (NEC-3), increased cytochrome-c in cytosol (NEC-2) confirming the enhanced cytotoxicity. To confirm the increased bioavailability, the intracellular curcumin was measured using fluorescence intensity. The fluorescent signal for intracellular curcumin was increased by 12, 30, and 21% for NEC-1, NEC-2, and NEC-3 respectively as compared to plain curcumin at 4h. Based on these results, we conclude that nanoencapsulated curcumin with whey protein will have potential to be considered for clinical applications for future studies.
- Ergocalciferol Versus Calcitriol for Controlling Chronic Kidney Disease Mineral Bone Disorder in stage 3 to 5 CKD: a Randomized Controlled Trial. [JOURNAL ARTICLE]
- Eur J Pharmacol 2016 Jul 8.
To compare the efficacy and safety of ergocalciferol and calcitriol in stage 3-5 chronic kidney disease (CKD) patients, a randomized, prospective, controlled, open-labeled study was designed. 204 patients were enrolled into the present study with following-up duration of 33.2±3.8 months. Patients in Group VitD2 (n=104) and Group aVitD3 (n=100) were treated by ergocalciferol and calcitriol, respectively. The 25-hydroxyvitamin D levels of group VitD2 increased significantly from 15.14±7.46 to 37.32±10.49 ng/ml (P<0.001, t=-19.692) and increased more (P<0.001, t=-14.982) than those of group aVitD3, which increased from 14.90±6.15 to 18.08±7.55 ng/ml. Maintenance target levels of serum calcium, phosphorus, and intact parathyroid hormone as the primary outcome measure did not show significant difference in frequencies between two groups. In summary, treatment of CKD-mineral and bone disorders in CKD patients at stages 3-5 using ergocalciferol has a similar long-term efficacy and safety profile as calcitriol.
- Local-anesthetic like inhibition of the cardiac Na(+) channel Nav1.5 α-subunit by 5-HT3 receptor antagonists. [JOURNAL ARTICLE]
- Eur J Pharmacol 2016 Jul 8.
5-hydroxytryptamine 3 receptor (5-HT3 receptor) antagonists are administered for prevention and therapy of nausea and vomiting. Although regarded as safe therapeutics, they can also provoke arrhythmias by prolonging the QRS interval. However, the mechanisms mediating this cardiotoxicity are poorly understood. Here we investigated effects of 5-HT3 receptor antagonists on the cardiac Na(+) channel Nav1.5. We explored the interaction of dolasetron, tropisetron, granisetron and ondansetron on the human α-subunit Nav1.5 heterologously expressed in HEK293 cells. Sodium currents were explored by means of whole-cell patch clamp recordings. All four substances inhibited the Nav1.5 in a concentration and state-dependent manner. Dolasetron displayed the lowest blocking efficacy, and tropisetron was the most potent blocker with a half maximum blocking concentration of 18µM for tonic block of inactivated channels. Tropisetron was also the most potent use-dependent inhibitor, and it also induced a strong open -channel block. Both tonic and use-dependent block by tropisetron were abbreviated on the local-anesthetic insensitive mutant Nav1.5-F1760A. Co-administration of tropisetron and the local anesthetic bupivacaine or the hypnotic propofol augmented inhibition of Nav1.5. Our data demonstrate that 5-HT3 receptor antagonists induce a local-anesthetic like inhibition of Nav1.5, and that they display different blocking efficacies. Reports on a relevant cardiotoxicity of dolasetron as opposed to other 5-HT3 receptor antagonists do not seem to correlate with a block of Nav1.5. As inhibition of Nav1.5 was enhanced by propofol and bupivacaine however, it is possible that a combined administration of Na(+) channel blockers and 5-HT3 receptor antagonists can provoke arrhythmias.
- Kidney-on-a-chip technology for renal proximal tubule tissue reconstruction. [JOURNAL ARTICLE]
- Eur J Pharmacol 2016 Jul 8.
The renal proximal tubule epithelium is responsible for active secretion of endogenous and exogenous waste products from the body and simultaneous reabsorption of vital compounds from the glomerular filtrate. The complexity of this transport machinery makes investigation of processes such as tubular drug secretion a continuous challenge for researchers. Currently available renal cell culture models often lack sufficient physiological relevance and reliability. Introducing complex biological culture systems in a 3D microfluidic design improves the physiological relevance of in vitro renal proximal tubule epithelium models. Organ-on-a-chip technology provides a promising alternative, as it allows the reconstruction of a renal tubule structure. These microfluidic systems mimic the in vivo microenvironment including multi-compartmentalization and exposure to fluid shear stress. Increasing data supports that fluid shear stress impacts the phenotype and functionality of proximal tubule cultures, for which we provide an extensive background. In this review, we discuss recent developments of kidney-on-a-chip platforms with current and future applications. The improved proximal tubule functionality using 3D microfluidic systems is placed in perspective of investigating cellular signalling that can elucidate mechanistic aberrations involved in drug-induced kidney toxicity.
- Anti-fibrotic effect of wogonin in renal tubular epithelial cells via Smad3-dependent mechanisms. [JOURNAL ARTICLE]
- Eur J Pharmacol 2016 Jul 7.
Renal fibrosis, a common feature and leading cause for End Stage Renal Disease, still lacks effective therapy. In the current study, we detected and compared the anti-fibrotic effects of wogonin and wogonoside, two major components of Scutellaria baicalensis Georgi, in TGF-β1-treated tubular epithelial cells of human and murine origins. Results consistently showed that compared with wogonoside, wogonin inhibits TGF-β1-induced upregulated mRNA and protein levels of collagen I and α-SMA with more efficiency, which was further confirmed by the immunofluorescence results that wogonin decreased the percentage of collagen I and α-SMA positive cells in TGF-β1-treated tubular epithelial cells. Mechanistically, wogonin mainly decreased Smad3 phosphorylation, but had marginal effect on non-canonical TGF-β signaling pathways, such as p38 and ERK MAP Kinase. Furthermore, in the cells deficient for TGF-β signaling or downstream Smad3, results demonstrated that even high concentration of wogonin failed to further decrease the level of collagen I and α-SMA, indicating the essential role of TGF-β/Smad3 signaling inhibition in the therapeutic action of wogonin in TGF-β1-stimulated tubular epithelial cells. Collectively, our results indicated that wogonin may be utilized as a potential anti-fibrotic Traditional Chinese Medicine monomer in the treatment of renal fibrosis.
- Inhibitory effects of hesperetin on Kv1.5 potassium channels stably expressed in HEK 293 cells and ultra-rapid delayed rectifier K(+) current in human atrial myocytes. [JOURNAL ARTICLE]
- Eur J Pharmacol 2016 Jul 7.
In the present study, the inhibitory effects of hesperetin (HSP) on human cardiac Kv1.5 channels expressed in HEK 293 cells and the ultra-rapid delayed rectifier K(+) current (Ikur) in human atrial myocytes were examined by using the whole-cell configuration of the patch-clamp techniques. We found that hesperetin rapidly and reversibly suppressed human Kv1.5 current in a concentration dependent manner with a half-maximal inhibition (IC50) of 23.15 μΜ with a Hill coefficient of 0.89. The current was maximally diminished about 71.36% at a concentration of 300μM hesperetin. Hesperetin significantly positive shifted the steady-state activation curve of Kv1.5, while negative shifted the steady-state inactivation curve. Hesperetin also accelerated the inactivation and markedly slowed the recovery from the inactivation of Kv1.5 currents. Block of Kv1.5 currents by hesperetin was in a frequency dependent manner. However, inclusion of 30μM hesperetin in pipette solution produced no effect on Kv1.5 channel current, while the current were remarkable and reversibly inhibited by extracellular application of 30μM hesperetin. We also found that hesperetin potently and reversibly inhibited the ultra-repaid delayed K(+) current (Ikur) in human atrial myocytes, which is in consistent with the effects of hesperetin on Kv1.5 currents in HEK 293 cells. In conclusion, hesperetin is a potent inhibitor of Ikur (which is encoded by Kv1.5), with blockade probably due to blocking of both open state and inactivated state channels from outside of the cell.