Fernand Gobeil

Université de Sherbrooke, Шербрук, Quebec, Canada

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Publications (122)442.98 Total impact

  • Domenico Regoli, Fernand Gobeil
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    ABSTRACT: Hypertension is characterized by an imbalance between the Renin-Angiotensin System (RAS) and the Kallikrein-Kinin System (KKS). Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II AT-1 receptor antagonists (also known as sartans or ARBs) are potent modulators of these systems and are highly effective as first-line treatments for hypertension, diabetic nephropathies, and diseases of the brain and coronary arteries. However, these agents are mechanistically distinct and should not be considered interchangeable. In this mini-review, we provide novel insights into the often neglected roles of the KKS in the beneficial, protective and reparative actions of ACEIs. Indeed, ACEIs are the only antihypertensive drugs that properly reduce the imbalance between the RAS and the KKS, thereby restoring optimal cardiovascular homeostasis and significantly reducing morbidity and the risk of all-cause mortality among individuals affected by hypertension and other cardiovascular diseases. SYNOPSIS AND BULLET POINTS: Copyright © 2015. Published by Elsevier Inc.
    Vascular Pharmacology 01/2015; 64. DOI:10.1016/j.vph.2014.12.003 · 4.62 Impact Factor
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    ABSTRACT: The traditional view of G protein-coupled receptors (GPCRs) being inactivated upon their internalization has been repeatedly challenged in recent years. GPCRs, in addition to forming the largest family of cell surface receptors, can also be found on intracellular membranes such as nuclear membranes. Since the first experimental evidence of GPCRs at the nucleus in the early 1990s, approximately 30 different GPCRs have been localized at the nucleus by independent research groups, including ours. In this chapter, we describe several techniques commonly used for immuno-detection of nuclear GPCRs focusing on subcellular fractionation of proteins based on their localization and transmission electron microscopy (TEM) using primary cultured cells as well as tissue sections. We also describe the use of confocal microscopy to study nuclear calcium currents, which can further affect downstream events such as gene transcription, nuclear envelope breakdown, or its reconstruction and nucleocytoplasmic protein transport.
    Methods in Molecular Biology 01/2015; 1234:81-97. DOI:10.1007/978-1-4939-1755-6_8 · 1.29 Impact Factor
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    ABSTRACT: Limb ischemia is a major complication of thromboembolic diseases. Diabetes worsens prognosis by impairing neovascularization. Genetic or pharmacological inactivation of the kallikrein-kinin system aggravates limb ischemia in non-diabetic animals while ACE/kininase II inhibition improves outcome. The role of kinins in limb ischemia in the setting of diabetes is not documented. We assessed whether selective activation of kinin receptors by pharmacological agonists can influence neovascularisation in diabetic mice with limb ischemia and have therapeutic effect. Selective pseudopeptide kinin B1 or B2 receptor agonists resistant to peptidase action were administered by osmotic minipumps at non-hypotensive dosage for 14 days after unilateral femoral artery ligation in mice previously rendered diabetic by streptozotocin. Comparison was made with ligatured, non-agonist treated non-diabetic and diabetic mice. Diabetes reduced neovascularisation, assessed by microangiography and histological capillary density analysis, by roughly 40%. B1 receptor agonist or B2 receptor agonist similarly restored neovascularization in diabetic mice. Neovascularization in agonist-treated diabetic mice was undistinguishable from non-diabetic mice. Both treatments restored blood flow in the ischemic hindfoot, measured by laser-doppler perfusion imaging. Macrophage infiltration increased 3 fold in the ischemic gastrocnemius muscle during B1 receptor agonist or B2 receptor agonist treatment and VEGF level 2 fold. Both treatments increased, by 50 to 100%, circulating CD45/CD11b-positive monocytes and CD34+/VEGFR2+ progenitor cells. Thus, selective pharmacological activation of B1 or B2 kinin receptor overcomes diabetes effect on postischemic neovascularization and restores tissue perfusion, through monocyte/macrophage mobilisation. Kinin receptors are potential therapeutic targets in limb ischemia in diabetes.
    Journal of Pharmacology and Experimental Therapeutics 11/2014; DOI:10.1124/jpet.114.219196 · 3.86 Impact Factor
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    ABSTRACT: Neurons have an important role in retinal vascular development. Here we show that the G protein-coupled receptor (GPCR) coagulation factor II receptor-like 1 (F2rl1, previously known as Par2) is abundant in retinal ganglion cells and is associated with new blood vessel formation during retinal development and in ischemic retinopathy. After stimulation, F2rl1 in retinal ganglion cells translocates from the plasma membrane to the cell nucleus using a microtubule-dependent shuttle that requires sorting nexin 11 (Snx11). At the nucleus, F2rl1 facilitates recruitment of the transcription factor Sp1 to trigger Vegfa expression and, in turn, neovascularization. In contrast, classical plasma membrane activation of F2rl1 leads to the expression of distinct genes, including Ang1, that are involved in vessel maturation. Mutant versions of F2rl1 that prevent nuclear relocalization but not plasma membrane activation interfere with Vegfa but not Ang1 expression. Complementary angiogenic factors are therefore regulated by the subcellular localization of a receptor (F2rl1) that governs angiogenesis. These findings may have implications for the selectivity of drug actions based on the subcellular distribution of their targets.
    Nature Medicine 09/2014; 20(10). DOI:10.1038/nm.3669 · 28.05 Impact Factor
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    ABSTRACT: We present a novel intradermal needle-free drug delivery device which exploits the unsteady high-speed flow produced by a miniature shock tube to entrain drug or vaccine particles onto a skin target. A first clinical study of pain and physiological response of human subjects study is presented, comparing the new injector to intramuscular needle injection. This clinical study, performed according to established pain assessment protocols, demonstrated that every single subject felt noticeably less pain with the needle-free injector than with the needle injection. Regarding local tolerance and skin reaction, bleeding was observed on all volunteers after needle injection, but on none of the subjects following powder injection. An assessment of the pharmacodynamics, via blood pressure, of pure captopril powder using the new device on spontaneously hypertensive rats was also performed. It was found that every animal tested with the needle-free injector exhibited the expected pharmacodynamic response following captopril injection. Finally, the new injector was used to study the delivery of an inactivated influenza vaccine in mice. The needle-free device induced serum antibody response to the influenza vaccine that was comparable to that of subcutaneous needle injection, but without requiring the use of an adjuvant. Although no effort was made to optimize the formulation or the injection parameters in the present study, the novel injector demonstrates great promise for the rapid, safe and painless intradermal delivery of systemic drugs and vaccines.
    Shock Waves 07/2013; DOI:10.1007/s00193-013-0464-5 · 0.74 Impact Factor
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    ABSTRACT: The low permeability of the BBB is largely responsible for the lack of effective systemic chemotherapy against primary and metastatic brain tumors. Kinin B1R and B2R have been shown to mediate reversible tumor-selective BBB disruption in preclinical animal models. We investigated whether co-administration of two novel potent kinin B1R and B2R agonists offers an advantage over administering each agonist alone for enhancing BBB permeability and tumor targeting of drugs in the malignant F98 glioma rat model. A new covalent kinin heterodimer that equally stimulates B1R and B2R was also constructed for the purpose of our study. We found that co-administration of B1R and B2R agonists, or alternatively administration of the kinin heterodimer more effectively delivered the MRI contrast agent Gd-DTPA and the anticancer drug carboplatin to brain tumors and surrounding tissues than the agonists alone (determined by MRI and ICP-MS methods). Importantly, the efficient delivery of carboplatin by the dual kinin receptor targeting on the BBB translated into increased survival of glioma-bearing rats. Thus, this report describes a potential strategy for maximizing the brain bioavailability and therapeutic efficacy of chemotherapeutic drugs.
    Cancer biology & therapy 06/2013; 14(9). DOI:10.4161/cbt.25327 · 3.63 Impact Factor
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    ABSTRACT: BACKGROUND AND PURPOSE: The contribution of endothelin-1 (ET-1) in a B2 KO mouse model of a high salt-induced arterial hypertension was investigated. EXPERIMENTAL APPROACH: Wild type (WT) or B2 KO mice receiving a normal (ND) or a high salt (HSD) diet were monitored by radio-telemetry up to a maximum of 18 weeks. At the 12th week of diet, subgroups under ND or HSD received by gavage the ETA antagonist A127722 during 5 days. In addition, blood samples were collected and, following euthanasia, the lungs, heart and kidneys were extracted, homogenized and assayed for ET-1 by radio-immuno assay (RIA). In a separate series of experiments, the ETA antagonist, BQ123 was tested against the pressor responses to a nitric oxide synthase inhibitor L-NAME in anesthetized WT and B2 KO mice. KEY RESULTS: In B2 KO but not WT mice, 12 weeks of HSD triggered a maximal increase of the mean arterial pressure (MAP) of 19.1 ± 2.8 mmHg, which was corrected by A127722 to MAP levels found in B2 KO mice under ND. Significant increases in immunoreactive ET-1 were detected only in the lungs of B2 KO mice under HSD. On the other hand, metabolic studies showed that sodium urinary excretion was markedly reduced in B2 KO compared to wild type mice under ND. Finally, BQ 123 (2 mg kg(-1) ) reduced by 50 % the pressor response to L-NAME (2 mg kg(-1) ) in B2 KO but not WT mice under anesthesia. CONCLUSIONS AND IMPLICATIONS: Our results support the concept that functional B2 receptors oppose high-salt induced increments in MAP, which are corrected by an ETA receptor antagonist in this mouse model of experimental hypertension.
    British Journal of Pharmacology 05/2013; 170(2). DOI:10.1111/bph.12259 · 4.99 Impact Factor
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    ABSTRACT: Leu-enkephalin analogs, in which the amide bonds were sequentially and systematically replaced either by ester or N-methyl amide bonds, were prepared using classical organic chemistry as well as solid phase peptide synthesis (SPPS). The peptidomimetics were characterized using competition binding, ERK1/2 phosphorylation, receptor internalization and contractility assays to evaluate their pharmacological profile over the delta opioid receptor (DOPr). The lipophilicity (LogD7.4) and plasma stability of the active analogs were also measured. Our results revealed that the last amide bond can be successfully replaced by either an ester or an N-methyl amide bond without significantly decreasing the biological activity of the corresponding analogs when compared to Leu-enkephalin. The peptidomimetics with an N-methyl amide function between residues Phe and Leu were found to be more lipophilic and more stable than Leu-enkephalin. Findings from the present study further revealed that the hydrogen-bond donor properties of the fourth amide of Leu-enkephalin are not important for its biological activity on DOPr. Our results show that the systematic replacement of amide bonds by isosteric functions represents an efficient way to design and synthesize novel peptide analogs with enhanced stability. Our findings further suggest that such a strategy can also be useful to study the biological roles of amide bonds.
    ACS Chemical Neuroscience 05/2013; 4(8). DOI:10.1021/cn4000583 · 4.21 Impact Factor
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    ABSTRACT: Cardiac ischemia is a leading cause of death, especially in diabetic patients. The diabetic ischemic heart is resistant experimentally to established cardioprotective treatments. New pharmacological approaches to cardiac protection are warranted. The kallikrein-kinin system is involved in myocardial protection in ischemia. Respective role of B1 (B1R) and B2 (B2R) receptors remains controversial. We tested whether pharmacological activation of kinin receptors may have therapeutic effect in cardiac ischemia-reperfusion in non diabetic (NDiab) and diabetic (Diab) mice. We assessed effect on infarct size (IS) and signaling pathways involved in myocardial protection of potent selective pharmacological agonists of B1R or B2R given at reperfusion. In NDiab mice, a B2R agonist reduced significantly IS by 47%, similarly to ramiprilat or ischemic postconditioning, via activation of PI3K/Akt pathway leading to inhibition of GSK3β. B1R agonist has no effect on IS. In contrast, in Diab mice, the B2R agonist, ramiprilat or ischemic postconditioning failed to reduce IS but a B1R agonist significantly reduced IS by 44% via activation of PI3K/Akt and ERK1/2, both leading to GSK3β inhibition. Differential effect of B2R or B1R agonists in NDiab and Diab mice can be linked to inactivation of B2R signaling and induction of B1R in heart of Diab mice. Thus, a pharmacological B2R agonist is cardioprotective in acute ischemia in non diabetic animals. B1R agonist overcomes resistance of diabetic heart to cardioprotective treatments. Pharmacological activation of B1R and B2R may become treatment for diabetic and non diabetic patients respectively in acute coronary syndromes.
    Journal of Pharmacology and Experimental Therapeutics 04/2013; 346(1). DOI:10.1124/jpet.113.203927 · 3.86 Impact Factor
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    ABSTRACT: Introduction Le syndrome coronarien aigu représente une des causes principales de mortalité particulièrement chez les patients diabétiques. Le système kallicréine kinine (SKK) est impliqué dans la cardioprotection lors de l’ischémie-reperfusion myocardique (IR). Cependant le coeur diabétique est résistant à la plupart des traitements cardioprotecteurs et le rôle du SKK lors de l’IR et du diabète est inconnu. Matériels et méthodes Nous avons testé l’effet de nouveaux agonistes sélectifs des récepteurs B1 (B1R) et B2 (B2R) des kinines, administrés lors de la reperfusion, chez des souris non diabétique et diabétiques soumises à une IR. Résultats Chez les souris non diabétique, l’agoniste B2R réduit la taille de l’infarctus de 47 %, similairement au ramiprilat et au postconditionnement ischémique, via l’activation de la voie PI3K/Akt et l’inhibition de GSK3-β. L’agoniste B1R n’a pas d’effet. Chez les souris diabétiques, l’agoniste B2R, le ramiprilat et le postconditionnement ischémique, n’ont pas d’effet. En revanche, l’agoniste B1R diminue la taille de l’infarctus de 44 % via l’activation des voies PI3K/Akt et ERK1/2, conduisant à l’inhibition de GSK3-β. L’effet différentiel des agonistes chez les souris diabétiques ou non est lié à une inactivation du signal du B2R et à une induction de la synthèse du B1R dans le coeur diabétique. Conclusion L’agoniste B2R est cardioprotecteur lors d’une IR chez les souris non diabétique. L’agoniste B1R permet de vaincre la résistance du coeur diabétique aux traitements cardioprotecteurs et pourrait représenter une nouvelle option thérapeutique chez les patients diabétiques lors d’un syndrome coronarien aigu.
    Diabetes & Metabolism 03/2013; 39:A9. DOI:10.1016/S1262-3636(13)71649-5 · 2.85 Impact Factor
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    ABSTRACT: Abstract We recently identified a novel human B2 receptor (B2R) agonist [Hyp3,Thi5,NChg7,Thi8]- bradykinin (NG291) with greater in vitro and in vivo potency and duration of action than natural bradykinin (BK). Here, we further examined its stability and selectivity toward B2R. The hypotensive, antithrombotic, and profibrinolytic functions of NG291 relative to BK and its analogue ([Hyp3,Thi5,(4-Me)Tyr8(ΨCH2NH)Arg9]-BK) (RMP-7) were also tested. Contraction assays using isolated mouse stomachs (containing kinin B1R, B2R, and kininase I- and II-like activities) showed that NG291 is a more potent contractant than BK and is inhibited by HOE-140 (B2R antagonist) but unaffected by R954 (B1R antagonist) while both decreased the potency of BK. In stomach tissues from B2R knockout mice, BK maintained its activity via B1R, whereas NG291 had no contractile effect, indicating that it was selective for B2R. Unlike BK, NG291 was not degraded by rabbit lung ACE. Comparing intravenously administered BK and NG291 revealed that NG291 exhibited more potent and prolonged hypotensive action and greater antithrombotic and profibrinolytic activities. These effects were of comparable magnitude to RMP-7 and were absent in B2R knockout mice. We concluded that NG291 is a novel biostable B2R-selective agonist that may prove suitable for investigating the (pre)clinical cardioprotective efficacy of B2R activation.
    Biological Chemistry 01/2013; 394(3). DOI:10.1515/hsz-2012-0295 · 2.69 Impact Factor
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    ABSTRACT: Background and PurposeThe contribution of endothelin‐1 (ET‐1) in a B2KO mouse model of a high salt‐induced arterial hypertension was investigated. Experimental ApproachWild‐type (WT) or B2KO mice receiving a normal diet (ND) or a high‐salt diet (HSD) were monitored by radiotelemetry up to a maximum of 18 weeks. At the 12th week of diet, subgroups under ND or HSD received by gavage the ETA antagonist A127722 during 5 days. In addition, blood samples were collected and, following euthanasia, the lungs, heart and kidneys were extracted, homogenized and assayed for ET‐1 by RIA. In a separate series of experiments, the ETA antagonist, BQ123 was tested against the pressor responses to a NOS inhibitor L‐NG‐nitroarginine methyl ester (L‐NAME) in anaesthetized WT and B2KO mice. Key ResultsIn B2KO, but not WT mice, 12 weeks of HSD triggered a maximal increase of the mean arterial pressure (MAP) of 19.1 ± 2.8 mmHg, which was corrected by A127722 to MAP levels found in B2KO mice under ND. Significant increases in immunoreactive ET‐1 were detected only in the lungs of B2KO mice under HSD. On the other hand, metabolic studies showed that sodium urinary excretion was markedly reduced in B2KO compared with WT mice under ND. Finally, BQ123 (2 mg·kg−1) reduced by 50% the pressor response to L‐NAME (2 mg·kg−1) in B2KO, but not WT mice under anaesthesia. Conclusions and ImplicationsOur results support the concept that functional B2 receptors oppose high salt‐induced increments in MAP, which are corrected by an ETA receptor antagonist in this mouse model of experimental hypertension.
    British Journal of Pharmacology 01/2013; 170(2). · 4.99 Impact Factor
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    ABSTRACT: [This corrects the article on p. e37485 in vol. 7.].
    PLoS ONE 06/2012; 7(6). DOI:10.1371/annotation/6b95427c-645d-4f1b-a648-ceb215129583 · 3.53 Impact Factor
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    ABSTRACT: Treatment of malignant glioma with chemotherapy is limited mostly because of delivery impediment related to the blood-brain tumor barrier (BTB). B1 receptors (B1R), inducible prototypical G-protein coupled receptors (GPCR) can regulate permeability of vessels including possibly that of brain tumors. Here, we determine the extent of BTB permeability induced by the natural and synthetic peptide B1R agonists, LysdesArg(9)BK (LDBK) and SarLys[dPhe(8)]desArg(9)BK (NG29), in syngeneic F98 glioma-implanted Fischer rats. Ten days after tumor inoculation, we detected the presence of B1R on tumor cells and associated vasculature. NG29 infusion increased brain distribution volume and uptake profiles of paramagnetic probes (Magnevist and Gadomer) at tumoral sites (T(1)-weighted imaging). These effects were blocked by B1R antagonist and non-selective cyclooxygenase inhibitors, but not by B2R antagonist and non-selective nitric oxide synthase inhibitors. Consistent with MRI data, systemic co-administration of NG29 improved brain tumor delivery of Carboplatin chemotherapy (ICP-Mass spectrometry). We also detected elevated B1R expression in clinical samples of high-grade glioma. Our results documented a novel GPCR-signaling mechanism for promoting transient BTB disruption, involving activation of B1R and ensuing production of COX metabolites. They also underlined the potential value of synthetic biostable B1R agonists as selective BTB modulators for local delivery of different sized-therapeutics at (peri)tumoral sites.
    PLoS ONE 05/2012; 7(5):e37485. DOI:10.1371/journal.pone.0037485 · 3.53 Impact Factor
  • Domenico Regoli, Gerard E Plante, Fernand Gobeil
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    ABSTRACT: In recent years, ACE Inhibitors (ACEIs) and Angiotensin II receptor antagonists (also known as AT1 receptor antagonists (AT1-RAs), angiotensin receptor blockers (ARBs), or Sartans), have become the drugs of choice for the treatment of hypertension, heart and renal failure, coronary artery diseases, myocardial infarction and diabetes. By suppressing angiotensin and potentiating bradykinin effects, ACEIs and ARBs activate hemodynamic, metabolic and cellular mechanisms that not only reduce high blood pressure, but also protect the endothelium, the heart, the kidney and the brain, namely the target organs which are at risk in cardiovascular diseases. Major therapeutic benefits of these drugs are the reduction of cardiovascular events and the amelioration of the quality of life and of the patient survival. Results from large clinical trials have established that ACEIs and ARBs are efficient and safe drugs, suitable for the chronic treatments of cardiovascular diseases. Side effects are rare and easily manageable in most cases. The following is a brief review of the basic actions and mechanisms by which two opposing systems, the renin-angiotensin (RAS) and the kallikrein-kinin (KKS), interact in the regulation of cardiovascular and fluid homeostasis to keep the balance in healthy life and correct the imbalance in pathological conditions. Here we discuss how and why imbalances created by overactive RAS are best corrected by treatments with ACEI or AT1-RAs.
    Pharmacology [?] Therapeutics 04/2012; 135(1):94-111. DOI:10.1016/j.pharmthera.2012.04.002 · 7.75 Impact Factor
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    ABSTRACT: Using immunofluorescence and 3-dimensional confocal microscopy techniques, the present study was designed to verify if NHE-1 is present at the level of the nuclear membrane in cells that are known to express this type of exchanger. Nuclei were isolated from aortic tissues of adult human, rabbit, and rats, as well as from liver tissues of human fetus, and adult rabbit and rat. In addition, cultured ventricular cardiomyocytes were isolated from 2-week-old rat. Our results showed the presence of NHE-1 in isolated nuclei of aortic vascular smooth muscle and liver of human, rabbit, and rat. NHE-1 seems to be distributed throughout the isolated nucleus and more particularly at the level of the nuclear membranes. The relative fluorescence density of NHE-1 was significantly higher (p < 0.05) in isolated liver nuclei of human, when compared with those of rabbit and rat. However, in isolated nuclei of aortic vascular smooth muscle, the relative fluorescence density of NHE-1 was significantly (p < 0.001) higher in the rabbit when compared with human and rat. In cultured rat ventricular cardiomyocytes, NHE-1 fluorescent labeling could be easily seen throughout the cell, including the nucleus, and more particularly at both the sarcolemma and the nuclear membranes. In rat cardiomyocytes, the relative fluorescence density of NHE-1 of the sarcolemma membrane, including the cytosol, was significantly lower than that of the whole nucleus (including the nuclear envelope membranes). In conclusion, our results showed that NHE-1 is present at the nuclear membranes and in the nucleoplasm and its distribution and density may depend on cell type and species used. These results suggest that nuclear membranes' NHE-1 may play a role in the modulation of intranuclear pH.
    Canadian Journal of Physiology and Pharmacology 02/2011; 82(8-9):805-11. DOI:10.1139/y04-119 · 1.55 Impact Factor
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    ABSTRACT: The mammalian type I gonadotropin releasing hormone receptor (GnRH-R) is a structurally unique G protein-coupled receptor (GPCR) that lacks cytoplasmic tail sequences and displays inefficient plasma membrane expression (PME). Compared to its murine counterparts, the primate type I receptor is inefficiently folded and retained in the endoplasmic reticulum (ER) leading to a further reduction in PME. The decrease in PME and concomitant increase in intracellular localization of the mammalian GnRH-RI led us to characterize the spatial distribution of the human and mouse GnRH receptors in two human cell lines, HEK 293 and HTR-8/SVneo. In both human cell lines we found the receptors were expressed in the cytoplasm and were associated with the ER and nuclear membrane. A molecular analysis of the receptor protein sequence led us to identify a putative monopartite nuclear localization sequence (NLS) in the first intracellular loop of GnRH-RI. Surprisingly, however, neither the deletion of the NLS nor the addition of the Xenopus GnRH-R cytoplasmic tail sequences to the human receptor altered its spatial distribution. Finally, we demonstrate that GnRH treatment of nuclei isolated from HEK 293 cells expressing exogenous GnRH-RI triggers a significant increase in the acetylation and phosphorylation of histone H3, thereby revealing that the nuclear-localized receptor is functional. Based on our findings, we conclude that the mammalian GnRH-RI is an intracellular GPCR that is expressed on the nuclear membrane. This major and novel discovery causes us to reassess the signaling potential of this physiologically and clinically important receptor.
    PLoS ONE 07/2010; 5(7):e11489. DOI:10.1371/journal.pone.0011489 · 3.53 Impact Factor
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    ABSTRACT: Treatment of malignant glioma with chemotherapy is limited mostly because of delivery impediment related to the blood-brain barrier (BBB). One approach for transporting drugs across the BBB involves the activation of bradykinin-B2 receptors (BK-B2R). Our objective was to pharmacologically characterize the BBB permeability induced by the synthetic biostable BK-B2R analogue [Phe(8)psi(CH(2)NH)Arg(9)]-BK (R523) in F98 glioma-implanted Fischer rats. On day 10 post-inoculation, we detected the presence of B2R in the tumor cells and the peritumoral microvasculature (RT-PCR and immunohistochemistry). We assessed BBB permeability before and after the intracarotid (i.c.) infusion of R523 (0.1ml/min for 5min; 2.5, 10, and 50nmol/kg/min) using non-invasive dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with the different sized-contrast agents Gd-DTPA (0.5kDa) and Gadomer (17kDa) (0.25mmol/kg via the caudal vein). T(1)-weighted images were analyzed for the presence or absence of contrast enhancement within and surrounding the tumor area and mathematically processed to yield a contrast agent distribution volume (CADV), which was used as an indicator of vascular permeability. Our results showed that the agonist R523 increased, in a dose-dependent manner, the CADV indexes of Gd-DTPA and Gadomer, with a maximum 2-fold increase in brain uptake of both CA. The increase in CADV induced by R523 (10nmol/kg/min) was prevented by the B2R antagonist HOE140 (20nmol/kg/min, i.c.) and the nitric oxide synthase inhibitor L-NA (5mg/kg, i.v.) but not by the B1R antagonist R892 (20nmol/kg/min, i.c.) or the cyclooxygenase inhibitor Meclofenamate (5mg/kg, i.v.). The BBB permeabilizing effect of R523 (10nmol/kg/min) lasted for <1h and was accompanied by a dose-related fall in arterial blood pressure. We concluded that R523 allows the extravasation of hydrophilic macromolecular agents (17kDa) into tumor tissues by inducing selective tumor BBB permeability via B2R- and NO-dependent mechanisms.
    Neuropeptides 04/2010; 44(2):177-85. DOI:10.1016/j.npep.2009.12.009 · 2.55 Impact Factor
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    ABSTRACT: Recent work from our group showed that the nuclear envelope membranes contain several G protein-coupled receptors, including prostaglandin E2 (EP3R) and endothelin-1 (ET-1) receptors. Activation of EP3R increased endothelial nitric oxide synthase (eNOS) RNA expression in nuclei. eNOS and inducible NOS (iNOS) are reported to also be present at the nuclear level. Furthermore, reactive oxygen species (ROS) were also localized at the nuclear level. In this review, we show that stimulation with NO donor sodium nitroprusside results in an increase of intranuclear calcium that was dependent on guanylate cyclase activation, but independent of MAPK. This increase in nuclear calcium correlated with an increase in nuclear transcription of iNOS. H2O2 and ET-1 increase both cytosolic and nuclear ROS in human endocardial endothelial cells and in human aortic vascular smooth muscle cells. This increase in ROS levels by H2O2 and ET-1 was reversed by the antioxidant glutathione. In addition, our results strongly suggest that cytosolic signalization is not only transmitted to the nucleus but is also generated by the nucleus. Furthermore, we demonstrate that oxidative stress can be sensed by the nucleus. These results highly suggest that ROS formation is also generated directly by the nucleus and that free radicals may contribute to ET-1 regulation of nuclear Ca2+ homeostasis.
    Canadian Journal of Physiology and Pharmacology 03/2010; 88(3):296-304. DOI:10.1139/Y10-011 · 1.55 Impact Factor
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    ABSTRACT: The morphological and functional integrity of the microcirculation is compromised in many cardiovascular diseases such as hypertension, diabetes, stroke, and sepsis. Angiotensin converting enzyme inhibitors (ACEi), which are known to favor bradykinin (BK) bioactivity by reducing its metabolism, may have a positive impact on preventing the microvascular structural rarefaction that occurs in these diseases. Our study was designed to test the hypothesis that BK, via B2 receptors (B2R), protects the viability of the microvascular endothelium exposed to the necrotic and apoptotic cell death inducers H(2)O(2) and LPS independently of hemodynamics. Expression (RT-PCR and radioligand binding) and functional (calcium mobilization with fura-2AM, and p42/p44MAPK and Akt phosphorylation assays) experiments revealed the presence of functional B2R in pig cerebral microvascular endothelial cells (pCMVEC). In vitro results showed that the cytocidal effects of H(2)O(2) and LPS on pCMVEC were significantly decreased by a BK pretreatment (MTT and crystal violet tests, annexin-V staining/FACS analysis), which was countered by the B2R antagonist HOE 140. BK treatment coincided with enhanced expression of the cytoprotective proteins COX-2, Bcl-2, and (Cu/Zn)SOD. Ex vivo assays on rat brain explants showed that BK impeded (by approximately 40%) H(2)O(2)-induced microvascular degeneration (lectin-FITC staining). The present study proposes a novel role for BK in microvascular endothelial protection, which may be pertinent to the complex mechanism of action of ACEi explaining their long-term beneficial effects in maintaining vascular integrity.
    Journal of Cellular Physiology 01/2010; 222(1):168-76. DOI:10.1002/jcp.21933 · 3.87 Impact Factor

Publication Stats

3k Citations
442.98 Total Impact Points

Institutions

  • 1992–2015
    • Université de Sherbrooke
      • • Faculty of Medicine and Health Sciences
      • • Department of Pharmacology
      • • Sherbrooke Institute of Pharmacology
      • • Department of Anatomy and Cell Biology
      Шербрук, Quebec, Canada
  • 2006
    • University of Texas at Dallas
      • Biochemistry
      Richardson, Texas, United States
  • 2001–2006
    • Université du Québec à Montréal
      Montréal, Quebec, Canada
  • 2000–2006
    • McGill University
      • Department of Pharmacology and Therapeutics
      Montréal, Quebec, Canada
  • 2003–2005
    • Université de Montréal
      Montréal, Quebec, Canada
  • 2003–2004
    • University of California, San Francisco
      • Department of Pediatrics
      San Francisco, California, United States
  • 2002–2003
    • CHU Sainte-Justine
      Montréal, Quebec, Canada
  • 1997–2002
    • University of Ferrara
      • • Department of Clinical and Experimental Medicine
      • • Section of Pharmacology
      Ferrare, Emilia-Romagna, Italy