Acute ethanol intake induces superoxide anion generation and mitogen-activated protein kinase phosphorylation in rat aorta: A role for angiotensin type 1 receptor

Ethanol intake is associated with increase in blood pressure, through unknown mechanisms. We hypothesized that acute ethanol intake enhances vascular oxidative stress and induces vascular dysfunction through renin-angiotensin system (RAS) activation. Ethanol (1 g/kg; p.o. gavage) effects were assessed within 30 min in male Wistar rats. The transient decrease in blood pressure induced by ethanol was not affected by the previous administration of losartan (10 mg/kg; p.o. gavage), a selective ATI receptor antagonist. Acute ethanol intake increased plasma renin activity (PRA), angiotensin converting enzyme (ACE) activity, plasma angiotensin I (ANG I) and angiotensin II (ANG II) levels. Ethanol induced systemic and vascular oxidative stress, evidenced by increased plasma thiobarbituric acid-reacting substances (TBARS) levels, NAD(P) H oxidase-mediated vascular generation of superoxide anion and p47phox translocation (cytosol to membrane). These effects were prevented by losartan. Isolated aortas from ethanol-treated rats displayed increased p38MAPK and SAPK/JNK phosphorylation. Losartan inhibited ethanol-induced increase in the phosphorylation of these kinases. Ethanol intake decreased acetylcholine-induced relaxation and increased phenylephrine-induced contraction in endothelium-intact aortas. Ethanol significantly decreased plasma and aortic nitrate levels. These changes in vascular reactivity and in the end product of endogenous nitric oxide metabolism were not affected by losartan. Our study provides novel evidence that acute ethanol intake stimulates RAS activity and induces vascular oxidative stress and redox-signaling activation through AT(1)-dependent mechanisms. These findings highlight the importance of RAS in acute ethanol-induced oxidative damage. (c) 2012 Elsevier Inc. All rights reserved.

Cannabinoid CB1 receptor restrains accentuated activity of hypothalamic corticotropin-releasing factor and brainstem tyrosine hydroxylase neurons in endotoxemia-induced hypophagia in rats

It is well known that endocannabinoids play an important role in the regulation of food intake and body weight. Endocannabinoids and cannabinoid receptors are found in the hypothalamus and brainstem, which are central areas involved in the control of food intake and energy expenditure. Activation of these areas is related to hypophagia observed during inflammatory stimulus. This study investigated the effects of cannabinoid (CB1) receptor blockade on lipopolysaccharide (LPS)-induced hypophagia. Male Wistar rats were pretreated with rimonabant (10 mg/kg, by gavage) or vehicle; 30 min later they received an injection of either LPS (100 mu g/kg, intraperitoneal) or saline. Food intake, body weight, corticosterone response, CRF and CART mRNA expression, Fos-CRF and Fos-alpha-MSH immunoreactivity in the hypothalamus and Fos-tyrosine hydroxylase (TH) immunoreactivity in the brainstem were evaluated. LPS administration decreased food intake and body weight gain and increased plasma corticosterone levels and CRF mRNA expression in the PVN. We also observed an increase in Fos-CRF and Fos-TH double-labeled neurons after LPS injection in vehicle-pretreated rats, with no changes in CART mRNA or Fos-alpha-MSH immunoreactive neurons in the ARC. In saline-treated animals, rimonabant pretreatment decreased food intake and body weight gain but did not modify hormone response or Fos expression in the hypothalamus and brainstem compared with vehicle-pretreated rats. Rimonabant pretreatment potentiated LPS-induced hypophagia, body weight loss and Fos-CRF and Fos-TH expressing neurons. Rimonabant did not modify corticosterone, CRF mRNA or Fos-alpha-MSH responses in rats treated with LPS. These data suggest that the endocannabinoid system, mediated by CB1 receptors, modulates hypothalamic and brainstem circuitry underlying the hypophagic effect during endotoxemia to prevent an exaggerated food intake decrease. This article is part of a Special Issue entitled 'Central Control of Food Intake'. (C) 2011 Elsevier Ltd. All rights reserved.

Bosentan, an endothelin receptor antagonist, ameliorates collagen-induced arthritis: the role of TNF-alpha in the induction of endothelin system genes

Endothelins (ETs) are involved in several inflammatory events. The present study investigated the efficacy of bosentan, a dual ETA/ETB receptor antagonist, in collagen-induced arthritis (CIA) in mice. CIA was induced in DBA/1J mice. Arthritic mice were treated with bosentan (100 mg/kg) once a day, starting from the day when arthritis was clinically detectable. CIA progression was assessed by measurements of visual clinical score, paw swelling and hypernociception. Histological changes, neutrophil infiltration and pro-inflammatory cytokines were evaluated in the joints. Gene expression in the lymph nodes of arthritic mice was evaluated by microarray technology. PreproET-1 mRNA expression in the lymph nodes of mice and in peripheral blood mononuclear cells (PBMCs) was evaluated by real-time PCR. The differences were evaluated by one-way ANOVA or Student's t test. Oral treatment with bosentan markedly ameliorated the clinical aspects of CIA (visual clinical score, paw swelling and hyperalgesia). Bosentan treatment also reduced joint damage, leukocyte infiltration and pro-inflammatory cytokine levels (IL-1 beta, TNF alpha and IL-17) in the joint tissues. Changes in gene expression in the lymph nodes of arthritic mice returned to the levels of the control mice after bosentan treatment. PreproET mRNA expression increased in PBMCs from rheumatoid arthritis (RA) patients but returned to basal level in PBMCs from patients under anti-TNF therapy. In-vitro treatment of PBMCs with TNF alpha upregulated ET system genes. These findings indicate that ET receptor antagonists, such as bosentan, might be useful in controlling RA. Moreover, it seems that ET mediation of arthritis is triggered by TNF alpha.

Toll-like receptor 2/MyD88 signaling mediates zymosan-induced joint hypernociception in mice: Participation of TNF-alpha, IL-1 beta and CXCL1/KC

Arthritic pain is a serious health problem that affects a large number of patients. Toll-like receptors (TLRs) activation within the joints has been implicated in pathophysiology of arthritis. However, their role in the genesis of arthritic pain needs to be demonstrated. In the present study, it was addressed the participation of TLR2 and TLR4 and their adaptor molecule MyD88 in the genesis of joint hypernociception (a decrease in the nociceptive threshold) during zymosan-induced arthritis. Zymosan injected in the tibio-tarsal joint induced mechanical hypernociception in C57BL/6 wild type mice that was reduced in TLR2 and MyD88 null mice. On the other hand, zymosan-induced hypernociception was similar in C3H/HePas and C3H/Hej mice (TLR4 mutant mice). Zymosan-induced joint hypernociception was also reduced in TNFR1 null mice and in mice treated with IL-1 receptor antagonist or with an antagonist of CXCR1/2. Moreover, the joint production of TNF-alpha, IL-1 beta and CXCL1/KC by zymosan was dependent on TLR2/MyD88 signaling. Investigating the mechanisms by which TNF-alpha, IL-1 beta and CXCL1/KC mediate joint hypernociception, joint administration of these cytokines produced mechanical hypernociception, and they act in an interdependent manner. In last instance, their hypernociceptive effects were dependent on the production of hypernociceptive mediators, prostaglandins and sympathetic amines. These results indicate that in zymosan-induced experimental arthritis, TLR2/MyD88 is involved in the cascade of events of joint hypernociception through a mechanism dependent on cytokines and chemokines production. Thus, TLR2/MyD88 signaling might be a target for the development of novel drugs to control pain in arthritis. (C) 2011 Elsevier B.V. All rights reserved.

MicroRNAs may mediate the down-regulation of neurokinin-1 receptor in chronic bladder pain syndrome

Bladder pain syndrome (BPS) is a clinical syndrome of pelvic pain and urinary urgency-frequency in the absence of a specific cause. Investigating the expression levels of genes involved in the regulation of epithelial permeability, bladder contractility, and inflammation, we show that neurokinin (NK)1 and NK2 tachykinin receptors were significantly down-regulated in BPS patients. Tight junction proteins zona occludens-1, junctional adherins molecule -1, and occludin were similarly down-regulated, implicating increased urothelial permeability, whereas bradykinin B(1) receptor, cannabinoid receptor CB1 and muscarinic receptors M3-M5 were up-regulated. Using cell-based models, we show that prolonged exposure of NK1R to substance P caused a decrease of NK1R mRNA levels and a concomitant increase of regulatory micro(mi)RNAs miR-449b and miR-500. In the biopsies of BPS patients, the same miRNAs were significantly increased, suggesting that BPS promotes an attenuation of NK1R synthesis via activation of specific miRNAs. We confirm this hypothesis by identifying 31 differentially expressed miRNAs in BPS patients and demonstrate a direct correlation between miR-449b, miR-500, miR-328, and miR-320 and a down-regulation of NK1R mRNA and/or protein levels. Our findings further the knowledge of the molecular mechanisms of BPS, and have relevance for other clinical conditions involving the NK1 receptor.

The cannabinoid CB1 receptor antagonists rimonabant (SR141716) and AM251 directly potentiate GABA(A) receptors

Rimonabant (SR141716) and the structurally related AM251 are widely used in pharmacological experiments as selective cannabinoid receptor CB(1) antagonists / inverse agonists. Concentrations of 0.5-10 µM are usually applied in in vitro experiments. We intended to show that these drugs did not act at GABA(A) receptors but found a significant positive allosteric modulation instead.

β-Caryophyllene ameliorates cisplatin-induced nephrotoxicity in a cannabinoid 2 receptor-dependent manner

(E)-β-caryophyllene (BCP) is a natural sesquiterpene found in many essential oils of spice (best known for contributing to the spiciness of black pepper) and food plants with recognized anti-inflammatory properties. Recently it was shown that BCP is a natural agonist of endogenous cannabinoid 2 (CB(2)) receptors, which are expressed in immune cells and mediate anti-inflammatory effects. In this study we aimed to test the effects of BCP in a clinically relevant murine model of nephropathy (induced by the widely used antineoplastic drug cisplatin) in which the tubular injury is largely dependent on inflammation and oxidative/nitrative stress. β-caryophyllene dose-dependently ameliorated cisplatin-induced kidney dysfunction, morphological damage, and renal inflammatory response (chemokines MCP-1 and MIP-2, cytokines TNF-α and IL-1β, adhesion molecule ICAM-1, and neutrophil and macrophage infiltration). It also markedly mitigated oxidative/nitrative stress (NOX-2 and NOX-4 expression, 4-HNE and 3-NT content) and cell death. The protective effects of BCP against biochemical and histological markers of nephropathy were absent in CB(2) knockout mice. Thus, BCP may be an excellent therapeutic agent to prevent cisplatin-induced nephrotoxicity through a CB(2) receptor-dependent pathway. Given the excellent safety profile of BCP in humans it has tremendous therapeutic potential in a multitude of diseases associated with inflammation and oxidative stress.

Induction of the Neurokinin 1 Receptor by TNFα in Endometriotic Tissue Provides the Potential for Neurogenic Control Over Endometriotic Lesion Growth

Context: Endometriosis is characterized by the growth of ectopic endometrial tissue. Nerve fibers are frequently associated with ectopic lesions, and neurogenic inflammation may play a role in endometriosis. Objective: The purpose of this study was to determine the presence of tachykinin receptors in endometriotic lesions and the role of TNFα on their expression. Design: This study was an assessment of matching eutopic and ectopic endometrial tissue and peritoneal fluid from patients with endometriosis and an in vitro analysis of primary endometrial cells. Setting: The setting was a university hospital. Patients: Participants were premenopausal women undergoing laparoscopy. Interventions: Endometriotic lesions were removed surgically. Main Outcome Measures: Tachykinin mRNA (TACR1/2) and protein (neurokinin 1 receptor [NK1R]) expression in both eutopic and ectopic endometrial tissue from patients with endometriosis and the correlation to peritoneal fluid TNFα were measured. Primary endometrial epithelial and stromal cells were assessed in vitro to determine the induction of TACR1/2 and NK1R expression after TNFα treatment. Cell viability of endometrial stromal cells after substance P exposure was also assessed. Results: Expression of both TACR1 and TACR2 mRNA was significantly higher in the ectopic than in the eutopic tissue. Both TACR1 mRNA and NK1R protein expression was significantly correlated with peritoneal fluid TNFα, and in vitro studies confirmed that TNFα treatment induced both TACR1 mRNA and NK1R protein expression in endometrial stromal cells. In endometrial stromal cells, substance P treatment enhanced cell viability, which was inhibited by a specific NK1R antagonist. Conclusions: NK1R expression is induced in ectopic endometrial tissue by peritoneal TNFα. Induction of NK1R expression may permit endometriotic lesion maintenance via exposure to substance P.

Effect of the NMDA-receptor antagonist dextromethorphan in infant rat pneumococcal meningitis

Excitatory amino acids (EAA) and particularly glutamate toxicity have been implicated in the pathogenesis of neuronal injury occurring in bacterial meningitis by activating the N-methyl-d aspartate (NMDA) receptor complex. Here, we evaluated the effect of adjuvant treatment with the antitussive drug dextromethorphan (DM), a non-competitive NMDA receptor antagonist with neuroprotective potential, in an infant rat model of pneumococcal meningitis. The experiments were carried out in postnatal day 6 (P6) and 11 (P11) animals. Pharmacokinetics of DM and its major metabolite dextrorphan (DO) were performed for dose finding. In our study, DM did not alter clinical parameters (clinical score, motor activity, incidence of seizures, spontaneous mortality) and cortical neuronal injury but increased the occurrence of ataxia (P<0.0001). When DM treatment was started at the time of infection (DM i.p. 15 mg/kg at 0, 4, 8 and 16 hours (h) post infection) in P11 animals, an aggravation of apoptotic neuronal death in the hippocampal dentate gyrus was found (P<0.05). When treatment was initiated during acute pneumococcal meningitis (DM i.p. 15 mg/kg at 12 and 15 h and 7.5 mg/kg at 18 and 21 h after infection), DM had no effect on the extent of brain injury but reduced the occurrence of seizures (P<0.03). We conclude that in this infant rat model of pneumococcal meningitis interference of the EEA and NMDA pathway using DM causes ataxia, attenuates epileptic seizures and increases hippocampal apoptosis, but is not effective in protecting the brain from injury.

The cannabinoid CB2 receptor-selective phytocannabinoid beta-caryophyllene exerts analgesic effects in mouse models of inflammatory and neuropathic pain

The widespread plant volatile beta-caryophyllene (BCP) was recently identified as a natural selective agonist of the peripherally expressed cannabinoid receptor 2 (CB2). It is found in relatively high concentrations in many spices and food plants. A number of studies have shown that CB2 is critically involved in the modulation of inflammatory and neuropathic pain responses. In this study, we have investigated the analgesic effects of BCP in animal models of inflammatory and neuropathic pain. We demonstrate that orally administered BCP reduced inflammatory (late phase) pain responses in the formalin test in a CB2 receptor-dependent manner, while it had no effect on acute (early phase) responses. In a neuropathic pain model the chronic oral administration of BCP attenuated thermal hyperalgesia and mechanical allodynia, and reduced spinal neuroinflammation. Importantly, we found no signs of tolerance to the anti-hyperalgesic effects of BCP after prolonged treatment. Oral BCP was more effective than the subcutaneously injected synthetic CB2 agonist JWH-133. Thus, the natural plant product BCP may be highly effective in the treatment of long lasting, debilitating pain states. Our results have important implications for the role of dietary factors in the development and modulation of chronic pain conditions.

Positron emission tomography (PET) imaging of prostate cancer with a gastrin releasing peptide receptor antagonist - from mice to men

UNLABELLED Ex vivo studies have shown that the gastrin releasing peptide receptor (GRPr) is overexpressed on almost all primary prostate cancers, making it a promising target for prostate cancer imaging and targeted radiotherapy. METHODS Biodistribution, dosimetry and tumor uptake of the GRPr antagonist ⁶⁴Cu-CB-TE2A-AR06 [(⁶⁴Cu-4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo(6.6.2)hexadecane)-PEG₄-D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-LeuNH₂] were studied by PET/CT in four patients with newly diagnosed prostate cancer (T1c-T2b, Gleason 6-7). RESULTS No adverse events were observed after injection of ⁶⁴Cu-CB-TE2A-AR06. Three of four tumors were visualized with high contrast [tumor-to-prostate ratio > 4 at 4 hours (h) post injection (p.i.)], one small tumor (T1c, < 5% tumor on biopsy specimens) showed moderate contrast (tumor-to-prostate ratio at 4 h: 1.9). Radioactivity was cleared by the kidneys and only the pancreas demonstrated significant accumulation of radioactivity, which rapidly decreased over time. CONCLUSION ⁶⁴Cu-CB-TE2A-AR06 shows very favorable characteristics for imaging prostate cancer. Future studies evaluating ⁶⁴Cu-CB-TE2A-AR06 PET/CT for prostate cancer detection, staging, active surveillance, and radiation treatment planning are necessary.

Copper-64 Labeled Macrobicyclic Sarcophagine Coupled to a GRP Receptor Antagonist Shows Great Promise for PET Imaging of Prostate Cancer

The gastrin-releasing peptide receptor (GRPr) is an important molecular target for the visualization and therapy of tumors and can be targeted with radiolabeled bombesin derivatives. The present study aims to develop statine-based bombesin receptor antagonists suitable for labeling with 64Cu for imaging by positron emission tomography (PET). The potent GRPr antagonist D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 was conjugated to the sarcophagine (3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane=Sar) derivative 5-(8-methyl-3,6,10,13,16,19-hexaaza-bicyclo[6.6.6]icosan-1-ylamino)-5-oxopentanoic acid (MeCOSar) via PEG4 (LE1) and PEG2 (LE2) spacers and radiolabeled with 64Cu2+ with >95% yield and specific activities of about 100 MBq/nmol. Both Cu(II) conjugates have high affinity for GRPr (IC50: natCu-LE1, 1.4±0.1 nM; natCu-LE2, 3.8±0.6 nM). The antagonistic properties of both conjugates were confirmed by Ca2+-flux measurements. Biodistribution studies of Cu-64-LE1 exhibited specific targeting of the tumor (19.6±4.7% IA/g at 1 h p.i.) and GRPr-positive organs. Biodistribution and PET images at 4 and 24 h postinjection showed increasing tumor-to-background ratios with time. This was illustrated by the acquisition of PET images showing high tumor-to-normal tissue contrast. This study demonstrates the high affinity of the MeCOSar-PEGx-bombesin conjugates to GRPr. The stability of 64Cu complexes of MeCOSar, the long half-life of 64Cu, and the suitable biodistribution profile of the 64Cu-labeled peptides lead to PET images of high contrast suitable for potential translation into the clinic.

Identification in mice of two isoforms of the cysteinyl leukotriene 1 receptor that result from alternative splicing

Two classes of human G protein-coupled receptors, cysteinyl leukotriene 1 (CysLT1) and CysLT2 receptors, recently have been characterized and cloned. Because the CysLT1 receptor blockers are effective in treating human bronchial asthma and the mouse is often used to model human diseases, we isolated the mouse CysLT1 receptor from a mouse lung cDNA library and found two isoforms. A short isoform cDNA containing two exons encodes a polypeptide of 339 aa with 87.3% amino acid identity to the human CysLT1 receptor. A long isoform has two additional exons and an in-frame upstream start codon resulting in a 13-aa extension at the N terminus. Northern blot analysis revealed that the mouse CysLT1 receptor mRNA is expressed in lung and skin; and reverse transcription–PCR showed wide expression of the long isoform with the strongest presence in lung and skin. The gene for the mouse CysLT1 receptor was mapped to band XD. Leukotriene (LT) D4 induced intracellular calcium mobilization in Chinese hamster ovary cells stably expressing either isoform of the mouse CysLT1 receptor cDNA. This agonist effect of LTD4 was fully inhibited by the CysLT1 receptor antagonist, MK-571. Microsomal membranes from each transformant showed a single class of binding sites for [3H]LTD4; and the binding was blocked by unlabeled LTs, with the rank order of affinities being LTD4 >> LTE4 = LTC4 >> LTB4. Thus, the dominant mouse isoform with the N-terminal amino acid extension encoded by an additional exon has the same ligand response profile as the spliced form and the human receptor.