European Journal of Pharmacology (v.620, #1-3)
Editorial Board (ii).
Effects of rolipram and diazepam on the adaptive changes induced by morphine withdrawal in the hypothalamic paraventricular nucleus by Cristina Núñez; Ana González-Cuello; Lorenzo Sánchez; M. Luisa Vargas; M. Victoria Milanés; M. Luisa Laorden (1-8).
A role for the cyclic AMP systems in the development of morphine dependence has been previously reported. In this study we investigated whether morphine dependence was inhibited by phosphodiesterase (PDE) 4 inhibitors rolipram and diazepam. Dependence on morphine was induced by a 7-day s.c. implantation of morphine pellets. On day 8, morphine withdrawal was precipitated by an injection of naloxone. In order to determine the effect of rolipram and diazepam rats were injected with these drugs once daily for seven days as well as 30 min before of naloxone injection. When opioid withdrawal was precipitated, an enhanced noradrenaline turnover and increased level of cyclic AMP and cyclic GMP in the hypothalamic paraventricular nucleus (PVN) were observed 30 min after naloxone administration. Moreover, c-Fos expression was induced in the PVN after naloxone-precipitated morphine withdrawal. Co-administration of rolipram or diazepam with morphine during the pre-treatment period, significantly reduced the signs of withdrawal, the enhancement of noradrenaline turnover and the increase in cyclic AMP. However, these inhibitors did not modify either levels of cyclic GMP or c-Fos expression in the PVN. These findings demonstrate that co-administration of rolipram or diazepam with morphine attenuate the withdrawal syndrome and suggest that these compounds may prevent the up-regulation of the cyclic AMP pathway and the associated increase in cyclic AMP level in morphine-withdrawn rats.
Keywords: PVN; Morphine-withdrawal; Noradrenaline turnover; Cyclic AMP; Cyclic GMP; c-Fos; Rolipram; Diazepam;
Neurite outgrowth induced by spicatoside A, a steroidal saponin, via the tyrosine kinase A receptor pathway by Jinyoung Hur; Pyeongjae Lee; Eunjung Moon; Insug Kang; Sung-Hoon Kim; Myung Sook Oh; Sun Yeou Kim (9-15).
Although nerve growth factor (NGF) therapy is an available option for the treatment of Alzheimer's disease, several limitations exist in its medical application. In the present study, we examined the neurotrophic effects of spicatoside A isolated from Liriope platyphylla on PC12 cells as well as the mechanisms involved in this process. Spicatoside A (10 μg/mL) induced neurite outgrowth similar to NGF (50 ng/mL). Furthermore, spicatoside A, a steroidal saponin, activated extracellular signal-regulated kinase 1/2 (ERK 1/2) and phosphatidylinositol 3-kinase (PI 3-kinase/Akt) via tyrosine receptor kinase A (TrkA), which is responsible for the induction of the neuritic process. The effects of NGF and spicatoside A on neurite outgrowth disappeared in TrkA knockdown PC12 cells by siRNA. In conclusion, neuritogenic effects resulting from spicatoside A may be involved in TrkA activation.
Keywords: Spicatoside A; Liriope platyphylla; Neurite outgrowth; Nerve growth factor;
Synergistic induction of heme oxygenase-1 by nicaraven after subarachnoid hemorrhage to prevent delayed cerebral vasospasm by Yasuhito Shimada; Hiroshi Tsunoda; Liqing Zang; Minoru Hirano; Takehiko Oka; Toshio Tanaka (16-20).
Cerebral vasospasm remains a major cause of morbidity and mortality in patients with subarachnoid hemorrhage. Heme oxygenase-1 (HO-1) is an oxidative stress-inducible enzyme with multiple protective functions against vascular and neurological diseases, including delayed cerebral vasospasm. In the present study, intravenous administration (i.v.) of nicaraven (1 mg/kg/min, for 2 days after subarachnoid hemorrhage) ameliorated delayed cerebral vasospasm in rat subarachnoid hemorrhage models, marked synergistic induction of HO-1 protein (> 2.5-fold than ‘subarachnoid hemorrhage with saline i.v.’), and elicited a rapid increase of cGMP accumulation in the basilar arteries. In the sham-operated rats, nicaraven could not induce HO-1 expression. Antisense HO-1 oligodeoxynucleotides abrogated this HO-1 induction and the antivasospastic effect of nicaraven. In vitro study using Hela cells, nicaraven enhanced the human HO-1 promoter (− 4.5 kbp) activity, which was pre-activated with the blood component oxyhemoglobin to mimic the ability of subarachnoid hemorrhage. These results suggest that this enhanced HO-1 expression through a combination of pathological state and pharmacological agent could be an effective strategy to improve the prognosis of heme- and oxidative stress-induced diseases, such as delayed cerebral vasospasm.
Keywords: HO-1; Delayed cerebral vasospasm; Subarachnoid hemorrhage and nicaraven;
Intrathecally injected Ile-Pro-Ile, an inhibitor of membrane ectoenzyme dipeptidyl peptidase IV, is antihyperalgesic in rats by switching the enzyme from hydrolase to synthase functional mode to generate endomorphin 2 by Kornél Király; Balázs Szalay; Judit Szalai; István Barna; Klára Gyires; Mathieu Verbeken; András Z. Rónai (21-26).
We have found recently that membrane-bound dipeptidyl peptidase IV (DPP-IV) generated extracellularly immunoreactive endomorphin-2 from Tyr-Pro precursor in a depolarisation-sensitive manner in rat isolated L4,5 dorsal root ganglia when the enzyme was switched to synthase mode by the hydrolase inhibitor Ile-Pro-Ile. Presently, we induced hyperalgesia in rats by injecting carrageenan into the right hindpaw and measured the reduction in nociceptive threshold (hyperalgesia) to pressure (Randall–Selitto test). The hyperalgesia, peaking at 180 min after injection, was fully reversed by intrathecal administration of 30 nmol/rat Ile-Pro-Ile. The antihyperalgesic action was antagonized by s.c. naloxone (1 mg/kg) and intrathecally injected specific antiserum to endomorphin-2 indicating that the opioid receptor-mediated effect was produced by an endogenously generated endomorphin-2-like immunoreactive substance. Intrathecal Ile-Pro-Ile was ineffective as an analgesic in the acute nociceptive test such as the rat tail-flick, whereas endomorphin-2 (EC50 = 13.3 nmol/rat), endomorphin-1 (6.8 nmol/rat), morphine (0.11 nmol/rat) and DAMGO (0.0059 nmol/rat) exerted opioid receptor-mediated analgesia given by the same route. We concluded that carrageenan-induced C-fiber barrage (wind-up) may create ideal conditions for the de novo synthesis of endomorphin-2 in rat spinal cord dorsal horns if the DPP-IV enzyme is switched to the synthase functional mode by Ile-Pro-Ile.
Keywords: Endomorphin-2 biosynthesis; Dipeptidyl peptidase IV; Carrageenan hyperalgesia; Ile-Pro-Ile; Intrathecal administration;
F15063, a potential antipsychotic with dopamine D2/D3 receptor antagonist and 5-HT1A receptor agonist properties: Influence on immediate-early gene expression in rat prefrontal cortex and striatum by Liesbeth A. Bruins Slot; Fabrice Lestienne; Catherine Grevoz-Barret; Adrian Newman-Tancredi; Didier Cussac (27-35).
Brain region-specific modulation of immediate-early gene (IEG) may constitute a marker of antipsychotic drug-like activity. We investigated the effects of the putative antipsychotic drug N-[(2,2-dimethyl-2,3-dihydro-benzofuran-7-yloxy)ethyl]-3-(cyclopent-1-enyl)-benzylamine (F15063), a compound that targets both dopamine D2 and serotonin 5-HT1A receptors, in comparison with haloperidol and clozapine on rat mRNA expression of IEG i.e. the zinc-fingered transcription factors c-fos, fosB, zif268, c-jun and junB, two transcription factors of the nuclear receptor family nur77 and nor1, and the effector IEG arc. F15063 (10 mg/kg) and clozapine (10 mg/kg), but not haloperidol (0.63 mg/kg), induced c-fos and fosB mRNA expression in prefrontal cortex, a region associated with control of cognition and negative symptoms of schizophrenia. In striatum, only c-fos, fosB, junB and nur77 were induced by clozapine whereas all IEG mRNAs were increased by haloperidol and F15063 (from 2.5 mg/kg) with similar high efficacy despite a total absence of F15063-induced catalepsy. However, at 0.63 mg/kg, F15063 induced a lower degree of striatal IEG mRNA expression than haloperidol and pretreatment with the serotonin 5-HT1A receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl-N-(2-pyridinyl)cyclohexane carboxamide trihydrochloride (WAY100635) (0.63 mg/kg) increased the level of IEG mRNA induction by F15063. Furthermore, (+)-8-hydroxy-2-(di-n-propylamino)tetralin [(+)-8-OH-DPAT] at 0.16 mg/kg decreased haloperidol-induced striatal IEG mRNA expression although it exerted no effects on its own. These results are consistent with an activation of serotonin 5-HT1A receptors by F15063, thus reducing D2 blockade-induced striatal IEG mRNA. Furthermore, the substantial F15063-induced expression of IEGs such as c-fos in striatum is not related to cataleptogenic activity and may act more as a marker of efficacious dopamine D2 receptor blockade.
Keywords: Dopamine D2 receptor; Serotonin 5-HT1A receptor; Antipsychotics; Schizophrenia; c-fos; Immediate-early gene;
Evaluation of amphetamine-induced hyperlocomotion and catalepsy following long-acting risperidone administration in rats by Giorgio Marchese; Gianluca Casu; Paola Casti; Gabriele Pinna Spada; Luca Pani (36-41).
It has been proposed that long-acting risperidone could provide a constant antipsychotic efficacy associated with a reduced liability to induce extra-pyramidal symptoms. To ascertain this hypothesis, antagonism of amphetamine-induced hyperlocomotion and catalepsy were analyzed in rats for a period of 1–6 weeks following long-acting risperidone (20–60 mg/kg) injection. Long-acting risperidone reduced amphetamine-induced hyperlocomotion after 2–5 weeks from drug injection, without producing significant extra-pyramidal symptoms. Following the administration of long-acting risperidone a constant ability to antagonize amphetamine-induced hyperlocomotion was observed during the day, but not when the antipsychotic was chronically administered using a short-acting formulation. The pre-clinical results confirmed that long-acting risperidone may represent an advance in antipsychotic therapy.
Keywords: Antipsychotic; Risperidone; Amphetamine; Catalepsy; Long-acting;
TRK-820, a selective kappa opioid receptor agonist, could effectively ameliorate L-DOPA-induced dyskinesia symptoms in a rat model of Parkinson's disease by Ken Ikeda; Satoru Yoshikawa; Takahiro Kurokawa; Natsumi Yuzawa; Kaoru Nakao; Hidenori Mochizuki (42-48).
Long-term therapy with L-3,4-dihydroxyphenylalanine (L-DOPA) in parkinsonian patients is known to lead to dyskinesia within a few years, and repeated administration of L-DOPA is also likely to alter the expression of kappa opioid receptors in the basal ganglia, especially the striatum and substantia nigra pars reticulata, suggesting that kappa opioid receptors might be deeply involved in motor functions. Therefore, effects of TRK-820 ((E)-N-[17-(cyclopropylmethyl)-4,5α-epoxy-3,14-dihydroxymorphinan-6β-yl]-3-(furan-3-yl)-N-methylprop-2-enamide monohydrochloride), a selective kappa opioid receptor agonist, were investigated on rotational behavior in unilateral 6-hydroxydopamine (6-OHDA)-treated rats (hemi-parkinsonian rats) and on L-DOPA-induced dyskinesia produced by administering L-DOPA to hemi-parkinsonian rats for 3 weeks (dyskinesia rats). A single administration of subcutaneous TRK-820 significantly increased spontaneous ipsilateral rotational behavior of hemi-parkinsonian rats at 30 µg/kg though the efficacy was moderate and also significantly inhibited L-DOPA-induced dyskinesia at 10 and 30 µg/kg; this inhibition was reversed in the presence of nor-binaltorphimine, a kappa opioid receptor antagonist. In vivo microdialysis study, TRK-820 (30 µg/kg, s.c.) significantly inhibited L-DOPA-derived extracellular dopamine content in the 6-OHDA-treated striatum in dyskinesia rats, but not in hemi-parkinsonian rats. Moreover, the development of L-DOPA-induced dyskinesia was suppressed by the 3-week co-administration of TRK-820 (3 and 10 µg/kg, s.c.) with L-DOPA. These results have suggested that TRK-820 ameliorates L-DOPA-induced dyskinesia with a moderate anti-parkinsonian effect by inhibiting L-DOPA-induced excessive dopamine release through kappa opioid receptors only in dyskinesia rats; therefore, TRK-820 is expected to become a useful agent for the treatment of L-DOPA-induced dyskinesia.
Keywords: Parkinson's disease; Dyskinesia; Kappa opioid receptor; TRK-820;
Amelioration of intracerebroventricular streptozotocin induced cognitive dysfunction and oxidative stress by vinpocetine — a PDE1 inhibitor by Rahul Deshmukh; Vivek Sharma; Sidharth Mehan; Nidhi Sharma; K.L. Bedi (49-56).
Enhancing cyclic nucleotides signaling by inhibition of phosphodiesterases (PDEs) is known to be beneficial in disorders associated with cognitive decline. The present study was designed to investigate the effect of vinpocetine (PDE1 inhibitor) on intracerebroventricular (i.c.v.) streptozotocin induced experimental sporadic dementia of Alzheimer's type. Infusion of streptozotocin impaired learning and memory, increased oxidative–nitritive stress and induced cholinergic hypofunction in rats. Chronic treatment with vinpocetine (5, 10 and 20 mg/kg i.p.) for 21 days following first i.c.v. streptozotocin infusion significantly improved learning and memory in Morris water maze and passive avoidance paradigms. Further, vinpocetine significantly reduced the oxidative–nitritive stress, as evidenced by decrease in malondialdehyde (MDA) and nitrite levels, and restored the reduced glutathione (GSH) levels. Significant increase in acetylcholinesterase activity and lactate dehydrogenase levels was observed in the present model indicating cholinergic hypofunction and increase in neuronal cell damage. Chronic treatment with vinpocetine also reduced significantly the increase in acetylcholinesterase activity and lactate dehydrogenase levels indicating restorative capacity of vinpocetine with respect to cholinergic functions and preventing the neuronal damage. The observed beneficial effects of vinpocetine on spatial memory may be due to its ability to favorably modulate cholinergic functions, prevent neuronal cell damage and possibly through its antioxidant mechanism also.
Keywords: Vinpocetine; Phosphodiesterase1; Cognitive dysfunction; Oxidative stress; Streptozotocin; Sporadic dementia of Alzheimer's type;
Role of potassium channels in regulation of rat coronary arteriole tone by Guo-bao Wu; En-xiang Zhou; Du-xin Qing; Jun Li (57-62).
Activity of potassium (K+) channels plays a key role in regulating arterial tone and therefore blood flow. But little is known about the roles of K+ channels in the coronary arterioles. The aim of the present study was to investigate the influences of several potassium channel blockers on resting vascular tone in isolated rat coronary arteriole. The coronary arterioles were carefully dissected, cannulated and pressurized. The inner diameter of vessels was recorded by a computerized diameter tracking system and the effects of K+ channels on the development of vascular myogenic tone was tested by application of various K+ channel inhibitors. Inhibition of voltage-dependent K+ (KV) channels and inward rectifier K+ (Kir) channels significantly increased the tone constriction. But inhibition of Ca2+-activated K+ (KCa) channels and ATP-sensitive K+ (KATP) channels had no effect on the resting tone. In addition, inhibition of nitric oxide synthase (NOS) further decreased the tone diameter. Combined inhibition of KV, Kir and NOS induced the strongest tone constriction. Our results suggested that activity of KV and Kir channels, and basal nitric oxide (NO) contribute to the myogenic tone in rat coronary arteriole under resting conditions, but basal NO may not contribute to the activation of KV and Kir channels. KCa and K ATP channels are likely to have a very low open probability under normal conditions.
Keywords: Potassium channels; Nitric oxide; Coronary arteriole and tone;
Adenosine monophosphate-activated protein kinase inhibits cardiac hypertrophy through reactivating peroxisome proliferator-activated receptor-α signaling pathway by Rong-Sen Meng; Zhao-hui Pei; Ran Yin; Cheng-Xi Zhang; Bao-Lin Chen; Yang Zhang; Dan Liu; An-Long Xu; Yu-Gang Dong (63-70).
The activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK) has been shown to inhibit cardiac hypertrophy, however, the mechanism remains unclear. Rat models of cardiac hypertrophy were created with transaortic constriction (TAC) to investigate the mechanistic role of AMPK involved. RT-PCR and Western blot analyses indicated that hypertrophy marker genes ANP and β-MHC expression were up-regulated in the myocardium of TAC rats. We also observed that the expressions of peroxisome proliferator-activated receptor-α (PPARα) and its target genes, carnitine palmitoyl transferase-І (CPT-І) and medium-chain acyl-COA dehydrogenases (MCAD), were down-regulated, and the fatty acid oxidation was decreased in TAC rats. Treatment of TAC animals with 5-aminoimidazole 1 carboxamide ribonucleoside (AICAR, 0.5 mg/g body wt), a specific activator of AMPK, inhibited cardiac hypertrophy in TAC and reversed PPARα, CPT-I and MCAD expression and fatty acid oxidation. Similar observations were made in hypertrophied cardiomyocytes induced by phenylephrine in vitro. Treatment of hypertrophied cardiomyocytes with Compound C, a specific AMPK inhibitor, showed an effect opposite to that of AICAR. The effect of AICAR on cardiac hypertrophy was blocked after PPARα was silenced by transfection of cardiomyocytes with PPARα-siRNA. Luciferase activity assay suggested that AICAR elevates PPARα transcriptional activity. These results indicate that AMPK plays an important role in the inhibition of cardiac hypertrophy by activating the PPARα signaling pathway.
Keywords: Cardiac hypertrophy; AICAR; AMPK; PPARα; Fatty acid oxidation;
Study of the mechanism of antihypertensive peptides VPP and IPP in spontaneously hypertensive rats by DNA microarray analysis by Naoya Yamaguchi; Kyosuke Kawaguchi; Naoyuki Yamamoto (71-77).
Many antihypertensive effects of angiotensin-I-converting enzyme (ACE) inhibitory peptides have been studied in spontaneously hypertensive rats (SHRs) and human, however, the mild actions of these peptides expressed by these consecutive uptakes are still not clear. Here, to understand the in vivo antihypertensive effects of well-characterized two peptides, Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP), DNA microarray was used to analyze gene expression in SHRs fed these peptides for 5 days. By using an Affymetrix analyzer, gene profiling was performed in a target organ, the aorta, of SHRs after repeated administration of VPP and IPP for 5 days. The changes in gene expression were relatively mild; therefore, among the analyzed genes associated with blood pressure, those that showed changes over ±5% as compared to the control group were categorized as the renin angiotensin aldosterone system, vascular function, arachidonic acid system, blood coagulation system, and cytokines and growth factors. Significant and marked differences were detected for the endothelial nitric oxide synthase (eNOS) gene (1.89-fold, P < 0.05) and the connexin 40 (gap junction 40) gene (2.81-fold, P < 0.05). Administration of VPP and IPP led to a slight increase in the expression of the cyclooxigenase (COX-1) gene and a decrease in the expression of both the nuclear factor kappa B subunit (NF-κB) gene for vascular function and the peroxisome proliferator activator receptor gamma (PPARγ) gene. Taken together, these results suggest that VPP and IPP function as ACE inhibitors in the aorta, where they may have a preventive role in cardiovascular function.
Keywords: Val-Pro-Pro; Ile-Pro-Pro; Angiotensin-I-converting enzyme inhibitory peptide; Spontaneously hypertensive rats;
The flavonoid dioclein is a selective inhibitor of cyclic nucleotide phosphodiesterase type 1 (PDE1) and a cGMP-dependent protein kinase (PKG) vasorelaxant in human vascular tissue by Roberta L. Gonçalves; Claire Lugnier; Thérèse Keravis; Miguel J. Lopes; Fernando A. Fantini; Martine Schmitt; Steyner F. Cortes; Virginia S. Lemos (78-83).
The inhibitory effect of the flavonoid dioclein was assessed on purified vascular cyclic nucleotide phosphodiesterase isoforms (EC 188.8.131.52, PDE1-5) in comparison with 8-methoxymethyl-isobutylmethylxanthine (8-MM-IBMX) and vinpocetine which are currently used as PDE1 inhibitors. The mechanism underlying the vasorelaxant effect of dioclein was investigated in human saphenous vein. Dioclein inhibited PDE1 more selectively than vinpocetine and 8-MM-IBMX, with IC50 values of 2.47 ± 0.26 and 1.44 ± 0.35 µM, respectively in basal- and calmodulin-activated states. Dioclein behaved as a competitive inhibitor for cGMP hydrolysis by PDE1 in basal- and calmodulin-activated states (K i = 0.62 ± 0.14 and 0.55 ± 0.07 µM, respectively), indicating this inhibitory effect to be independent of calmodulin interactions. In addition, dioclein induced a concentration-dependent relaxation of human saphenous vein which was independent on the presence of functional endothelium (EC50 values of 7.3 ± 3.1 and 11 ± 2.7 µM, respectively with and without endothelium). 8-MM-IBMX relaxed human saphenous vein with an EC50 = 31 ± 16 µM, whereas vinpocetine did not cause any vasorelaxation at concentrations up to 100 µM. Rp-8-pCPT-cGMPS, which inhibits cGMP-dependent protein kinase (PKG), blocked the vasodilator effect of dioclein, whereas H-89, which is a cAMP-dependent protein kinase (PKA) inhibitor, had a minor inhibitory effect. Our data show that dioclein is a potent calmodulin-independent selective inhibitor of PDE1 and that inhibition of PDE1 is involved in the PKG-mediated vasorelaxant effect of dioclein in human saphenous vein. Furthermore, dioclein may represent a new archetype to develop more specific PDE1 inhibitors.
Keywords: Human saphenous vein; Rp-8-pCPT-cGMPS; H-89; Vinpocetine; 8-methoxymethyl-IBMX; Endothelium;
Sesamin improves endothelial dysfunction in renovascular hypertensive rats fed with a high-fat, high-sucrose diet by Xiang Kong; Jie-ren Yang; Li-qun Guo; Ying Xiong; Xiang-qi Wu; Kai Huang; Yong Zhou (84-89).
The present study was designed to evaluate the possible in vivo protective effects of sesamin on hypertension and endothelial function in two-kidney, one-clip renovascular hypertensive rats fed with a high-fat, high-sucrose diet (2K1C rats on HFS diet). Sesamin was orally administered for 8 weeks in 2K1C rats on HFS diet. Then, the serum malondialdehyde level was determined. The protein expression of endothelial nitric oxide synthase (eNOS), nitrotyrosine and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit p47phox in aortas was detected by Western blotting. Vasorelaxation response to acetylcholine and nitroprusside, and functional assessment of nitric oxide (NO) bioactivity were also determined in aortic rings. Sesamin treatment reduced systolic blood pressure, improved vasodilatation induced by acetylcholine and enhanced NO bioactivity in the thoracic aortas. These changes were associated with increased eNOS, decreased malondialdehyde content, and reduced nitrotyrosine and p47phox protein expression. All these results suggest that chronic treatment with sesamin reduces hypertension and improves endothelial dysfunction through upregulation of eNOS expression and reduction of NO oxidative inactivation in 2K1C rats on HFS diet.
Keywords: Endothelial dysfunction; Endothelial nitric oxide synthase; NADPH oxidase; Sesamin;
Characterization of the contractile 5-hydroxytryptamine receptor in the autoperfused kidney of L-NAME hypertensive rats by Asunción Morán; Ana-Vega Ortiz de Urbina; María-Luisa Martín; Alicia Rodríguez-Barbero; Luis San Román (90-96).
We evaluated the renal vascular effects of serotonin in Nω-Nitro-l-arginine-hypertensive rats (L-NAME, 30 mg/kg/day, administered over 21 days in drinking water), a model of systemic hypertension with glomerular capillary hypertension and renal disease due to chronic blockade of endogenous synthesis of nitric oxide (NO) and compared with those obtained in normotensive rats.Using several agonists and antagonists of 5-hydroxytryptamine (5-HT), we characterized the receptor subtypes involved in the contractile response to 5-HT in the in-situ autoperfused rat kidney.An intra-arterial (i.a.) bolus injection of 5-HT (0.00000125–0.1 µg/kg) increased renal perfusion pressure in a dose-dependent manner, but did not affect systemic blood pressure. The selective 5-HT2 receptor agonist α-methyl-5-hydroxytryptamine (α-methyl-5-HT) caused a local vasoconstrictor effect in the autoperfused rat kidney. The selective 5-HT2B receptor agonist BW723C86, the non-selective 5-HT2C receptor agonist (1-(3-chlorophenyl) piperazine), m-CPP, the 5-HT1 receptor agonist 5-carboxamidotryptamine (5-CT) and the selective 5-HT3 receptor agonist (1-(m-chlorophenyl)-biguanide), m-CPBG, did not modify renal perfusion pressure. The vasoconstrictor effect elicited by α-methyl-5-HT was significantly decreased by the 5-HT2 receptor antagonist ritanserin and the 5-HT2A receptor antagonist spiperone, but was not modified by pretreatment with the selective 5-HT2B/2C receptor antagonist (3,5-dihydro-5-methyl-N-3pyridinylbenzo[1,2.b:4,5-b′]dipyrrole(1H)-carboxamide hydrochloride), SB206553.The results of protein expression analyses allow us to postulate that the 5-HT2A receptor protein 5HT-SRC is expressed in renal tissue and differentially expressed in the renal artery of hypertensive (L-NAME) rats. Our data suggest that the serotonergic vasoconstrictor response induced in the in-situ autoperfused hypertensive rat kidney would be mediated by local activation of the 5-HT2A receptor.
Keywords: 5-Hydroxytryptamine; L-NAME (Nω-Nitro-l-arginine); 5-HT2A receptor; Autoperfused rat kidney;
Differential roles of dihydropyridine calcium antagonist nifedipine, nitrendipine and amlodipine on gentamicin-induced renal tubular toxicity in rats by Jin Li; Qi-xiong Li; Xian-fei Xie; Ying Ao; Chao-rong Tie; Ren-jie Song (97-104).
In the present study, we investigated the antioxidative potencies of dihydropyridine calcium antagonists prototype nifedipine, the second generation drug nitrendipine, and the long acting, third generation drug amlodipine on gentamicin-induced renal tubular toxicity in Sprague–Dawley rats. In addition, we analyzed the relationship between renal tubular cell apoptosis and the antioxidative properties of these dihydropyridine calcium antagonists. Results showed that treatment with gentamicin alone caused significant changes in the levels of urinary protein, urinary N-acetyl-beta-d-glucosaminidase, serum creatinine, and blood urea nitrogen. Nifedipine and amlodipine effectively reversed the effect of gentamicin on these parameters. In contrast, nitrendipine either had no effect or worsened gentamicin-induced changes in the levels of urinary protein, urinary N-acetyl-beta-d-glucosaminidase, serum creatinine, and blood urea nitrogen. Furthermore, gentamicin treatment caused significant increases in the levels of malondialdehyde, nitric oxide, nitric oxide synthase and significant decreases in the levels of reduced glutathione, glutathione-S-transferase, and superoxide dismutase in kidney tissues. These effects were dramatically reduced by nifedipine and amlodipine but not affected by nitrendipine. In addition to the biochemical changes, histopathological studies showed that gentamicin caused structural damages in the kidneys; renal tubular cell apoptosis, a decrease in Bcl-2 expression and an increase in Bax expression were observed in all rats treated with gentamicin, nifedipine and amlodipine effectively reversed the effect of gentamicin while nitrendipine worsened them. In conclusion, this study clearly indicated that nifedipine and amlodipine protected against gentamicin-induced nephrotoxicity while nitrendipine had little effect, or even worsened.
Keywords: Nifedipine; Nitrendipine; Amlodipine; Gentamicin; Nephrotoxicity; Antioxidation;
Effect of phenylethanoid glycosides and polysaccharides from the seed of Plantago asiatica L. on the maturation of murine bone marrow-derived dendritic cells by Dan-Fei Huang; Yong-Fu Tang; Shao-Ping Nie; Yin Wan; Ming-Yong Xie; Xiao-Mei Xie (105-111).
The seed of Plantago asiatica L. is one of the most popular folk herbal medicines used in China and other Asian countries. In this study, phenylethanoid glycosides and polysaccharides were isolated from the seed of P. asiatica L. by using phytochemical investigation methods. A screening model of immunological activity by using dendritic cells as target cells was established to investigate the effects of these compounds on the phenotypic and functional maturation of dendritic cells. Compared with untreated cells, dendritic cells treated with acteoside, isoacteoside or polysaccharides expressed higher level of class II MHC and costimulatory molecule CD86 (B7-2). Functional maturation was confirmed by decreased endocytosis and increased naïve T cell stimulatory activity of dendritic cells. These results showed that acteoside, isoacteoside and polysaccharides from the seed of P. asiatica L. had significant immunoenhancing activity by inducing the maturation of dendritic cells.
Keywords: Plantago asiatica L.; Phenylethanoid glycoside; Polysaccharide; Dendritic cell;
Anti-inflammatory and analgesic activity of a novel inhibitor of microsomal prostaglandin E synthase-1 expression by María Dolores Guerrero; Maurizio Aquino; Ines Bruno; Raffaele Riccio; María Carmen Terencio; Miguel Payá (112-119).
In a previous study, we reported a new γ-hydroxybutenolide derivative, 4-benzo[b]thiophen-2-yl-3-bromo-5-hydroxy-5H-furan-2-one (BTH), as inhibitor of microsomal prostaglandin E synthase-1 (mPGES-1) expression in lypopolysaccharide (LPS) stimulated RAW 264.7 and TPH-1 cells, without affecting cyclooxygenase-2 (COX-2). In this study, we evaluated the in vivo effect of BTH on some acute and chronic inflammatory animal models in relation to its inhibitory profile on mPGES-1 expression. In the zymosan-induced mouse air pouch model, BTH produced a dose-dependent inhibition of prostaglandin E2 (PGE2) production and mPGES-1 protein expression in pouch exudates without any effect on COX-2 protein expression. This behavior was confirmed in the chronic model of collagen-induced arthritis, where administration of BTH (5 mg/kg) clearly reduced PGE2 and mPGES-1 expression in joint tissues, whereas COX-2 was unaffected. These effects were accompanied by the suppression of clinical and histopathological manifestations of disease such as the loss of proteoglycan, and the destruction of surface cartilage. Other enzymes participating in the metabolism of arachidonic acid, such as prostaglandin I2 synthase, tromboxane A2 synthase or 5-lipoxygenase were unaffected by this compound. The acetic acid-induced hyperalgesia model in LPS-sensitized mice showed a dose-dependent analgesic effect of BTH, exerting an ED50 value of 6.2 mg/kg. Our data suggest that inhibition of mPGES-1 protein expression in acute and chronic inflammatory models by BTH, could provide a potential therapeutic target and a pharmacological tool to discern the role of the inducible enzymes COX-2 and mPGES-1 in inflammatory pathologies.
Keywords: 4-benzo[b]thiophen-2-yl-3-bromo-5-hydroxy-5H-furan-2-one; Inflammation; Mouse air pouch; Collagen-induced arthritis; Analgesia; Microsomal prostaglandin E synthase-1 expression;
Anti-inflammatory and vascularprotective properties of 8-prenylapigenin by Tiziana Paoletti; Silvia Fallarini; Francesca Gugliesi; Alberto Minassi; Giovanni Appendino; Grazia Lombardi (120-130).
Flavonoids display several biological activities, but exhibit poor oral absorption and rapid metabolism. To improve their pharmacological profile four C8-prenyl flavonoids, structurally related to the anti-inflammatory lead apigenin, were synthesized, and the two least cytotoxic (IC50 > 30 μM) compounds [8-prenylnaringenin (8-PN) and 8-prenylapigenin (8-PA)] in RAW 264.7 murine macrophages were assayed against a panel of biological targets. The anti-inflammatory properties of these compounds were evaluated in an in vitro model of inflammation [cells exposed to 0.1 μg/ml lipopolysaccharide (LPS) for 24 h]. Both 8-PN and 8-PA were equally effective and potent in inhibiting the LPS-induced gene expression [tumor necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2] (RT-PCR) and release (ELISA) of pro-inflammatory mediators [TNF-α, NO, prostaglandin (PG)E2], through mechanisms involving the inhibition of nuclear factor-κB (NF-κB) activation (EMSA) and reactive oxygen species accumulation [2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) determination]. One-digit nM concentrations of 8-PN or 8-PA induced a significant increase in the basal production of the atheroprotective prostacyclin (PGI2) by human umbilical vein endothelial cells (HUVEC), with maximal effects at 10 nM. Both NS-398, a specific COX-2 inhibitor, and ICI 182 780, a non-selective estrogen receptor antagonist, abolished the activity of these compounds, suggesting a COX- and estrogen receptor-dependent mechanism of activity. 8-PA, a weaker estrogenic compound than 8-PN, resulted only 2-fold less potent than 8-PN in potentiating PGI2 production by HUVEC, qualifying this C8-prenyl flavonoid as a lead for the rational design of new anti-inflammatory and vascularprotective compounds.
Keywords: Flavonoid; Inflammation; Prostacyclin; Pro-inflammatory mediator; Antioxidant;
Ameliorative effect of berberine on endothelial dysfunction in diabetic rats induced by high-fat diet and streptozotocin by Chunmei Wang; Jing Li; Xiaoyan Lv; Ming Zhang; Yanfang Song; Li Chen; Yanjun Liu (131-137).
Berberine can improve insulin resistance, lower blood glucose, and regulate lipid metabolism disorders which cause endothelial dysfunction, leading to vascular complications of type 2 diabetes mellitus. The aim of the present study was to investigate the effects of berberine on endothelial dysfunction of aortas in type 2 diabetes mellitus rats and its mechanism. Wistar rats were randomly divided into four groups: diabetic rats, control rats, diabetic rats treated with berberine (100 mg/kg), and control rats treated with berberine. The serum fasting blood glucose, insulin, total cholesterol, triglyceride and nitric oxide (NO) levels were tested. Acetylcholine-induced endothelium-dependent relaxation and sodium nitroprusside induced endothelium-independent relaxation were measured in aortas for estimating endothelial function. The expression of endothelial nitric oxide synthase (eNOS) mRNA was measured by RT-PCR, and the protein expressions of eNOS and NADPH oxidase (NOX4) were analyzed by western blot. The results showed that berberine significantly decreased fasting blood glucose, and triglyceride levels in diabetic rats. Berberine also improved endothelium-dependent vasorelaxation impaired in aorta. The expressions of eNOS mRNA and protein were significantly increased, while NOX4 protein expression was decreased in aortas from diabetic rats with berberine treatment. Moreover, serum NO levels were elevated after berberine treatment. In conclusion, berberine restores diabetic endothelial dysfunction through enhanced NO bioavailability by up-regulating eNOS expression and down-regulating expression of NADPH oxidase.
Keywords: Diabetes; Nitric oxide; eNOS; Berberine; Endothelial dysfunction;
Role of Nrf2 in prevention of high-fat diet-induced obesity by synthetic triterpenoid CDDO-Imidazolide by Soona Shin; Junko Wakabayashi; Melinda S. Yates; Nobunao Wakabayashi; Patrick M. Dolan; Susan Aja; Karen T. Liby; Michael B. Sporn; Masayuki Yamamoto; Thomas W. Kensler (138-144).
The synthetic oleanolic triterpenoid 1-[2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole (CDDO-Imidazolide or CDDO-Im) is an extremely potent activator of Nrf2 signaling. In cells undergoing adipogenesis, CDDO-Im prevents lipid accumulation in an Nrf2-dependent manner. However, in vivo evidence for effects of CDDO-Im on obesity is lacking. The goals of these studies were to determine if CDDO-Im can prevent high-fat diet-induced obesogenesis in the mouse, and to elucidate the molecular target of drug action. Wild-type and Nrf2-disrupted C57BL/6J female mice were dosed 3 times per week with 30 μmol/kg CDDO-Im or vehicle by oral gavage, during 95 days of access to a control diet or a high-fat diet. Body weights, organ weights, hepatic fat accumulation and gene expression were measured. Treatment with CDDO-Im effectively prevented high-fat diet-induced increases in body weight, adipose mass, and hepatic lipid accumulation in wild-type mice but not in Nrf2-disrupted mice. Wild-type mice on a high-fat diet and treated with CDDO-Im exhibited higher oxygen consumption and energy expenditure than vehicle-treated mice, while food intake was lower in CDDO-Im-treated than vehicle-treated mice. Levels of gene transcripts for fatty acid synthesis enzymes were downregulated after CDDO-Im treatment in the liver of wild-type mice. This inhibitory effect of CDDO-Im on lipogenic gene expression was significantly reduced in Nrf2-disrupted mice. The results indicate that CDDO-Im is an exceedingly potent agent for preventing obesity, and identify the Nrf2 pathway as a novel target for management of obesogenesis.
Keywords: Nrf2; Diet-induced obesity; Fatty acid synthase; Triterpenoid;