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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Serine hydrolase activity and roles for monoacylglycerol lipase in innate immunity and intestinal inflammation

Ambrose, Timothy James William January 2018 (has links)
Detection of evolutionarily conserved pathogen motifs by pattern recognition receptors (PRRs), particularly on dendritic cells (DCs), is crucial for adequate immune responses. Defects in DC function are known to be associated with inflammatory bowel disease (IBD). The endocannabinoid system (ECS) is the system through which exocannabinoids such as Δ<sup>9</sup>-tetrahydrocannabinol and cannabidiol signal. Regarding inflammation, cannabinoids generally exert anti-inflammatory effects, including on experimental colitis. However, most work has been performed in animal models and less is known about the function of this system in human immune cells, particularly DCs. Monoacylglycerol lipase (MGLL) is the key enzyme for hydrolysis of the endocannabinoid 2-arachidonoylglycerol, and a member of the serine hydrolase enzyme superfamily. This thesis defines the activity of serine hydrolase enzymes for the first time in human DCs upon stimulation by NOD2/TLR2 ligands using activity-based protein profiling (ABPP). MGLL is shown to be ubiquitously upregulated upon stimulation of DCs and in monocyte-derived macrophages. Through pharmacological inhibition studies, MGLL is demonstrated to regulate cellular and secreted lipids, not limited to endocannabinoids. However, overall DC function is independent of this enzyme suggesting that the effects of lipid modulation may be on bystander cells. Challenging the current literature, MGLL inhibition with a novel inhibitor worsens murine Citrobacter rodentium colitis. Finally, ABPP demonstrates a rich serine hydrolome in colonic tissue from human IBD with many enzymes previously undefined in this disease. Gene expression of ECS components suggests the enzymes ABHD12 and DAGLα/β may be potential markers of field change in IBD.
12

Effects of endocannabinoid (CB1) receptor antagonism on insulin resistance in a rodent model of metabolic syndrome

Lindborg, Katherine Ann January 2010 (has links)
The endocannabinoid system is a novel pharmacological target in the treatment of metabolic syndrome. Antagonism of the endocannabinoid-1 receptor (CB1R) leads to a transient reduction in food intake, a sustained decrease in body weight and an improvement in metabolic parameters in animal models of obesity. Skeletal muscle is the primary tissue involved in glucose uptake in response to insulin, and insulin sensitivity of skeletal muscle is vital to the maintenance of whole-body euglycemia. Little is known regarding the effects of CB1R antagonism on skeletal muscle glucose transport activity. The purpose of this dissertation was to test the hypothesis that antagonism of the CB1R activates signaling molecules of the insulin signaling pathway to increase glucose transport activity in normal and insulin-resistant skeletal muscle, thereby improving whole-body glucose tolerance. CB1R antagonism with SR141716 directly enhanced basal and insulin-stimulated glucose transport activity in skeletal muscle from lean and obese Zucker while activation of the CB1R with ACEA, decreased glucose transport activity. Key proteins associated with regulation of glucose transport activity were not altered by either CB1R agonism (ACEA) or antagonism (SR141716). Chronic CB1R antagonist treatment (10 mg/kg SR141716 i.p. / 14 days) also enhanced insulin-stimulated glucose transport activity in skeletal muscle of both lean and obese animals, again with no alteration in relevant signaling factors. Plasma free fatty acids (FFAs) were decreased in chronically-treated lean and obese animals and whole-body insulin sensitivity was improved in obese Zucker rats. The enhanced insulin sensitivity seen in chronically-treated obese animals was associated with a dramatic reduction in insulin secretion following a glucose challenge. Acute CB1R antagonism in obese animals also elicited a reduction in insulin secretion following a glucose challenge; however, with no improvement of whole-body insulin sensitivity. Acute CB1R antagonist treatment did not alter skeletal muscle glucose transport activity or circulating FFAs for any animals. These data suggest that although CB1R antagonism directly enhances basal and insulin stimulated glucose transport in skeletal muscle of lean and obese rats, direct action on the skeletal muscle is not responsible for the improvement in insulin-stimulated glucose transport activity and whole-body insulin sensitivity seen in chronically-treated obese animals.
13

Possível interação entre os sistemas endocanabinóide, glutamatérgico e nitrérgico do CPFmv na modulação de respostas emocionais/comportamentais ao estresse / Possible interaction between endocannabinoid, glutamatergic and nitrergic systems into the mvPFC in the modulation of emotional / behavioral response to stress

Ariandra Guerini Sartim 22 September 2017 (has links)
Receptores CB1 e TRPV1 desempenham papéis opostos na modulação da atividade neuronal e, possivelmente, na regulação da resposta ao estresse. A exposição ao estresse reduz a neurotransmissão mediada por receptores CB1, enquanto que a facilitação do sistema endocanabinóide produz efeito tipoantidepressivo. Por outro lado, estudos farmacológicos e de manipulação genética apontam que a diminuição da sinalização mediada por receptores TRPV1 produz efeito tipo-antidepressivo em modelos animais. Evidências científicas apontam que a modulação da neurotransmissão glutamatérgica, dependente de receptores NMDA, esteja envolvida em respostas mediadas por CB1 e TRPV1. Ambos os receptores são amplamente expressos em estruturas cerebrais envolvidas na resposta emocional, incluindo o córtex pré-frontal medial ventral (CPFmv), o que aponta para essa estrutura como importante alvo para os efeitos mediados por receptores CB1, TRPV1 e NMDA. Entretanto, pouco se sabe sobre a interação entre CB1 e TRPV1 corticais na resposta ao estresse. Dessa forma, avaliamos se receptores CB1 e TRPV1 localizados no CPFmv-pré-límbico (PL) podem contribuir, de maneiras opostas, para as mudanças comportamentais induzidas pelo estresse do teste do nado forçado (TNF), um teste preditivo de efeito tipo-antidepressivo. Em um primeiro grupo experimental observou-se que a AEA induz efeito tipo-antidepressivo com uma curva dose-resposta em U, quando administrada no CPFmv-PL. Além disso, o efeito tipo-antidepressivo da AEA foi prevenido pela pré-administração de AM251, um antagonista para receptores CB1. Por outro lado, a maior dose de AEA, que não induz efeito per se, produziu efeito tipo-antidepressivo quando combinada ao bloqueio de receptores TRPV1 por meio do pré-tratamento com SB366791. Corroborando estes dados, observou-se que a administração intra-CPFmv-PL de um bloqueador dual da enzima FAAH e de receptores TRPV1 (AA-5HT), induziu efeito tipo-antidepressivo no teste do nado forçado. Além disso, a administração do inibidor da FAAH (URB597) e do antagonista de receptores TRPV1 (SB366791), em grupos independentes de animais, reduziu o tempo de imobilidade no teste do nado forçado. Ademais, a coadministração de doses subefetivas de URB597 e SB366791 reduziu o tempo de imobilidade no mesmo teste comportamental, evidenciando somação de efeito do bloqueio combinado da FAAH com receptores TRPV1. Em conjunto, esses ii resultados indicam que tanto a facilitação da neurotransmissão mediada por CB1R quanto o bloqueio de TRPV1R no CPFmv-PL promove efeito tipo-antidepressivo, sugerindo que ambos os receptores corticais são importantes na modulação de respostas comportamentais ao estresse e, possivelmente, na neurobiologia da depressão, porém de maneiras opostas. Buscando elucidar os mecanismos pelos quais a AEA, através da ativação de CB1R e TRPV1R, promove seus efeitos comportamentais, o envolvimento da das neurotransmissões glutamatérgica e nitrérgica nos efeitos induzidos pela AEA foi investigado. Nossos resultados demonstraram que a administração de antagonista de receptores glutamatérgicos do tipo NMDA (LY235959) e de inibidor da nNOS (NPA) induziram efeito tipoantidepressivo no teste do nado forçado quando administrados intra-CPFmv-PL. Além disso, a coadministração de doses subefetivas do antagonista NMDA (LY366791) e da AEA intra-CPFmv-PL, induziu efeito tipo-antidepressivo no TNF, mostrando um efeito aditivo da administração conjunta das drogas. Esse resultado sugere que o efeito tipo-antidepressivo da AEA seja facilitado pela inibição da neurotransmissão glutamatérgica mediada por NMDA. Em conjunto, os resultados do presente trabalho indicam um envolvimento de CB1 e TRPV1 do CPFmv-PL na modulação da resposta comportamental ao estresse do nado forçado, porém de maneira contrária. Além disso, o efeito tipo-antidepressivo da AEA parece envolver a diminuição da neurotransmissão glutamatérgica mediada por NMDAR. / CB1 and TRPV1 receptors play opposite roles in the modulation of neuronal activity and, possibly, in the regulation of the stress response. Exposure to stress attenuates CB1 receptor-mediated neurotransmission, while facilitation of the endocannabonoid system produces antidepressant-like effects. On the other hand, genetic and pharmacological blockade of TRPV1 receptor signalling produces antidepressant-like effect in animal models. Scientific evidence suggests NMDA receptor-mediated glutamatergic neurotransmission might be involved in responses mediated by CB1 and TRPV1. Both receptors are widely expressed in brain structures involved in the emotional response, including the ventral medial prefrontal cortex (CPFmv), which points to this structure as an important target to the effects triggered by CB1 and TRPV1. However, little is known about the interaction between cortical CB1 and TRPV1 in response to stress. Therefore, we evaluated whether CB1 and TRPV1 receptors of the vmPFC-PL may contribute, in opposite ways, to stress-induced behavioral changes in the forced swimming test (FST), a predictive test of antidepressant-like effect. In a first experimental group it was observed that AEA induces antidepressant-like effect with a U shape dose-response curve, when administered in the vmPFC-PL. In addition, the antidepressant-like effect of AEA was prevented by pre-administration with AM251, a CB1 receptor antagonist. On the other hand, the higher dose of AEA, which does not induce effect per se, produced an antidepressant-like effect when combined with TRPV1 receptor blockade with SB366791. Corroborating these data, intra-vmPFC-PL administration of a dual blocker of the FAAH enzyme and TRPV1 receptors (AA-5HT), induced antidepressant-like effect in the forced swimming test. In addition, administration of FAAH inhibitor (URB597) and TRPV1 receptor antagonist (SB366791) in independent groups of animals reduced the immobility time in the forced swimming test. Furthermore, co-administration of URB597 and SB366791, in sub-effective doses, reduced the immobility time in the same behavioral test, evidencing synergism of the combined blockade of FAAH with TRPV1 receptors. Taken together, these results indicate that both facilitation of CB1R-mediated neurotransmission and blockade of TRPV1R in vmPFC-PL promotes antidepressantlike effect, suggesting that both cortical receptors are important in modulating iv behavioral responses to stress and possibly in the neurobiology of depression, but in opposite ways. Aiming to elucidate the mechanisms by which AEA, through the activation of CB1R and TRPV1R, promotes its behavioral effects, the involvement of the possible modulation of glutamatergic and nitrergic neurotransmissions by AEA was investigated. Our results demonstrated that administration of NMDA receptor antagonist (LY235959) and nNOS inhibitor (NPA) induced antidepressant-like effect in the forced swimming test when administered intra-CPFmv-PL. In addition, coadministration of NMDA antagonist (LY366791) and AEA intra-CPFmvPL, in subeffective doses, induced antidepressant-like effect in the FST, showing a synergistic effect of these drugs. This result suggests that the antidepressant-like effect of AEA might involve attenuation of cortical NMDA-mediated glutamatergic neurotransmission. Taken together, results of the present study indicate an opposite involvement for CB1 and TRPV1 receptors in the behavioral responses elicited by forced swimming stress. Furthermore, the antidepressant-like effect of AEA probably involves the attenuation of NMDAR-mediated glutamatergic neurotransmission.
14

Participação do sistema canabinoide em processos oxidativo e inflamatório relacionados à neurodegeneração in vitro. / Participation of the cannabinoid system in oxidative and inflammatory processes related to neurodegeneration in vitro.

Hadassa Batinga da Silva 08 December 2014 (has links)
A ativação do receptor CB1, leva a modulação de processos intracelulares que muda a resposta celular de acordo com o estímulo, além de estar envolvida em mecanismos de proliferação, diferenciação, movimentação e morte celular. O objetivo desse trabalho foi avaliar a participação desse sistema em processos oxidativo e inflamatório relacionados à neurodegeneração in vitro. Foi utilizado a linhagem de neuroblastoma Neuro2a diferenciada em células dopaminérgicas que foram expostas a três condições: com 6OHDA, H2O2 e LPS e co-tratadas com o agonista do receptor CB1 ACEA e o antagonista/agonista inverso AM251 por 24 horas. Utilizamos parâmetros funcionais de viabilidade celular, produção de espécies reativas de oxigênio e técnica de western blot. O tratamento com ACEA ou ACEA/AM251 produziram um aumento da viabilidade celular nos três modelos de exposição propostos; redução da produção de espécies reativas de oxigênio e ativação da via da proteína ERK1/2, além da inibição da morte celular pela diminuição da expressão da caspase 3. Concluímos que os canabinoides escolhidos foram capazes de proteger as células dopaminérgicas do dano oxidativo e inflamatório através do aumento da sobrevida celular por diminuição da produção de ROS. / The CB1 receptor activation leads to modulation of intracellular processes that change the cellular response according to the stimulus, as well as being involved in mechanisms of proliferation, differentiation, cell movement and death. The present study evaluated the participation of this system in oxidative and inflammatory processes related to neurodegeneration in vitro. We have used the Neuro2A neuroblastoma lineage, which those were differentiated into dopaminergic cells, and exposed to 6OHDA, H2O2 and LPS. They were co-treated with ACEA, CB1 receptor agonist, and AM251, the CB1 receptor antagonist/inverse agonist, for 24 hours. We used functional parameters of cell viability, production of reactive oxygen species and protein analyses by western blot. Treatment with ACEA or ACEA/AM251 produced an increase in cell viability; reduced production of reactive oxygen species and activation of the ERK1/2 protein, in addition to inhibition of cell death by decreasing the expression of caspase 3 in all three models proposed. We concluded that chosen cannabinoids were able to protect dopaminergic cells from oxidative damage and inflammation through the increased cell survival by decreasing the production of ROS.
15

Anatomical Characterization of the Type-1 cannabinoid receptors in specific brain cell populations of mutant mice / Caractérisation anatomique des récepteurs cannabinoïdes de type 1 dans des populations de cellules cérébrales spécifiques de souris mutantes.

Gutierrez Rodriguez, Ana 02 December 2016 (has links)
Dans cette thèse l’expression du récepteur CB1 dans l’hippocampe de souris mutantes ré-exprimant spécifiquement le gène spécifiquement dans certains types cellulaires du cerveau tels que : les neurones glutamatergiques du télencéphale dorsal, et les neurones GABAergiques a été analysé. De plus, dans le but de connaître la distribution anatomique exacte des récepteurs CB1 astrogliaux par rapport aux synapses excitatrices et inhibitrices, j’ai étudié l’expression des récepteurs CB1 dans les astrocytes de souris exprimant le récepteur CB1 seulement dans les astrocytes et une souris mutante ciblée pour exprimer la protéine cytoplasmique hrGFP diffusible dans les cellules astrogliales, ce qui permet une meilleure détection des prolongements astrocytaires. Les conclusions de ce travail de thèse sont les suivantes : la distance la plus commune entre le récepteur CB1 astroglial et la synapse la plus proche est de 400 à 800 nm. La majorité des synapses entourées par des astrocytes immunopositifs pour le récepteur CB1 dans l’hippocampe, est de nature excitatrice. Les souris mutantes ré-exprimant le récepteur CB1 caractérisées dans ce travail de thèse montrent : 1) l’expression du récepteur CB1 dans différents types cellulaires, 2) la réexpression est limitée à une population neuronale particulière ou aux astrocytes, 3) les niveaux endogènes de récepteurs CB1 sont maintenus dans les différents types cellulaires ré-exprimant le récepteur CB1. De façon générale, ces résultats nous montrent que les souris mutantes ré-exprimant le récepteur CB1 sont d’excellents outils pour l’étude fonctionnelle et translationnelle sur le rôle de ce récepteur dans le cerveau sain ou pathologique. / The Cannabinoid Type I receptor protein (CB1) expression in the hippocampus of rescue mice modified to express the gene exclusively in specific brain cell types: such as dorsal telencephalic glutamatergic neurons, or GABAergic neurons have been analyzed. Furthermore, aiming at knowing the exact anatomical distribution of the astroglial CB1 receptors with respect to the excitatory and inhibitory synapses, the CB1 receptor expression in astrocytes of mouse expressing CB1 receptor only in astrocytes and mutant mouse expressing the protein hrGFP into astrocytes (that allows for better detection of the astrocytic processes) have been also investigated. The results showed that the majority of the hippocampal synapses surrounded by CB1 receptor immunopositive astrocytes in the 400-800 nm range are of excitatory nature. Moreover, the CB1 receptor rescue mutant mice characterized in this Doctoral Thesis have proven 1) to express CB1 receptors in specific brain cell types; 2) the re-expression is limited to the particular brain cell populations; 3) the endogenous levels of CB1 receptors are maintained in the brain cell types re-expressing the receptor. Which makes this mutant mice excellent tools for functional and translational investigations on the role of the CB1 receptors in the normal and diseased brain.
16

Novel Insights into CB1 Receptor Signaling and the Anabolic Role of Cannabinoid Receptors in Bone

Marcu, Jahan Phillip January 2013 (has links)
Activation of the CB1 receptor is modulated by aspartate residue D2.63176 in transmembrane helix (TMH) II. Interestingly, D2.63 does not affect the affinity for ligand binding at the CB1 receptor. Studies in class A GPCRs have suggested an ionic interaction between residues of TMHII and VII. In this report, modeling studies identified residue K373, in the extracellular (EC)-3 loop, in charged interactions with D2.63. We investigated this possibility by performing reciprocal mutations and biochemical studies. D2.63176A, K373A, D2.63176A-K373A, and the reciprocal mutant with the interacting residues juxtaposed, D2.63176K-K373D were characterized using radioligand binding and guanosine 5'-3-O-(thio)triphosphate functional assays. None of the mutations resulted in a significant change in the binding affinity of CP55,940 or SR141716A. Computational results indicate that the D2.63176-K373 ionic interaction strongly influences the conformation(s) of the EC-3 loop, providing a structure-based rationale for the importance of the EC-3 loop to signal transduction in CB1. Specifically, the putative ionic interaction results in the EC-3 loop pulling over the top (extracellular side) of the receptor; this EC-3 loop conformation may serve protective and mechanistic roles. These results suggest that the ionic interaction between D2.63176 and K373 is crucial for CB1 signal transduction. This work may help to aide drug design efforts for the effective treatment of different diseases. The cannabinoid receptors of osteoblasts may represent a target for the treatment of bone disorders such as osteoporosis. Our research demonstrates that cannabinoids can affect important signaling molecules in osteoblasts. In MC3T3-E1 osteoblastic cells, the CB1 antagonist, AM251, has been reported to induce increases in Runx2 mRNA, mineralized bone nodule formation, and activation of signaling molecules such as ERK and AKT (Wu et al., 2011). Studies from our lab characterizing mice in which both CB1 and CB2 receptors were inactivated by homologous recombination have demonstrated increased bone mass coupled with enhanced osteoblast differentiation of bone marrow stromal cells in culture (manuscript in preparation). We explored the effect of antagonizing CB1 and CB2 cannabinoid receptors in osteoblastic cells to gain insights into molecular pathways that may help to explain the effects of the endocannabinoid system (ECS) in bone development. Our data was generated by running time course experiments with MC3T3-E1 cells under the influence of SR141716A, SR144528 or both in combination. The cells were harvested with a lysis buffer at specific time points and analyzed by western blot analysis. Quantification of protein activation was calculated using LiCor imaging equipment and software. Within 15 minutes, treatment with the CB1 receptor antagonist SR141716A resulted in several fold increases in pERK, pSMAD158, and pAKT. SR144528, a CB2 receptor antagonist, caused increases in pERK and pSMAD158, but not pAKT. When both antagonists were applied together, pERK and pSMAD158 levels increased, while pAKT signaling was diminished compared to SR141716A alone. The finding that cannabinoid receptor antagonists alter the activity of the SMAD158 complex is a novel finding, which suggests that cannabinoids can influence bone morphogenic signaling pathways, and therefore play a significant role in osteoblast differentiation and function. / Cell Biology
17

Design and Synthesis of CB1 Receptor Ligands and Synthesis of Amphibian Alkaloids

Shu, Hong 20 December 2009 (has links)
Our project was aimed at the development of novel CB1 cannabinoid receptor antagonists that may have clinical applications for the treatment of cannabinoid and psychostimulant addiction. In this study, we designed, synthesized, and established the CB1 affinity for the 1,5-diaryl-1,2,3- triazole esters, a series of 4,5-diaryl-1-substituted-1,2,3-triazole analogues and a series of 4,5- diaryl-2-substituted-1,2,3-triazoles. Our research group has been interested in the synthesis of amphibian alkaloids due to their interesting biological activities. We have recently developed a general synthetic strategy which can rapidly prepare a few amphibian alkaloids simply from the abundant natural product (-)- cocaine This strategy was first successfully applied to the synthesis of (-)-monomorine. More recently, this strategy has also been utilized in the syntheses of both of the enantiomers of cispyrrolidine 225H and (+)-gephyrotoxin 287C.
18

Rôle des récepteurs aux cannabinoïdes 1 (CB1R) du tissu adipeux sur la lipolyse et conséquences sur le métabolisme glucido-lipidique de la souris / Role of adipose tissue cannabinoid 1 receptor (CB1R) on lipolysis and consequences on lipid and carbohydrate metabolism in mice

Muller, Tania 08 December 2017 (has links)
Rôle des récepteurs aux cannabinoïdes 1 (CB1R) du tissu adipeux sur la lipolyse et conséquences sur le métabolisme glucido-lipidique de la souris.L’obésité s’accompagne d’une dérégulation de la lipolyse responsable d’une libération excessive d’Acides Gras Libres (AGL) qui sont des acteurs majeurs dans la mise en place de la résistance périphérique à l’insuline. En parallèle, il est maintenant bien établi qu’au cours de l’obésité, une altération de l’activité du Système EndoCannabinoïde (SEC) dans plusieurs tissus métaboliques est observée. S’il est bien décrit que l’hyperactivation de ce système au sein du Tissu Adipeux (TA) favorise son expansion, les conséquences sur la lipolyse adipocytaire restent à déterminer.Ces travaux de thèse ont pour objectif principal de préciser le rôle du SEC dans la régulation de la lipolyse. Pour cela, l’AEA, un agoniste des récepteurs aux cannabinoïdes 1 (CB1R) et le JZL195, un inhibiteur des enzymes de dégradation des endocannabinoïdes, ont été utilisés in vivo chez la souris et in vitro sur un modèle d’explants pour augmenter le tonus endocannabinoïde dans le TA et en mesurer les conséquences sur l’activité lipolytique. Ensuite, les effets du blocage du SEC sur la lipolyse ont été étudiés chez la souris obèse par l’utilisation d’un antagoniste spécifique des CB1R, le Rimonabant.Ces travaux montrent que l’activation du SEC adipocytaire dans des conditions d’insulinémie élevée (période postprandiale) conduit à une altération du signal insulinique et à une perte de son effet antilipolytique favorisant le relargage d’AGL et pouvant, à terme, conduire à des effets délétères sur les tissus périphériques. A l’inverse, lorsque les voies de signalisation à l’insuline sont peu actives comme c’est le cas au cours du jeûne, la stimulation du SEC s’accompagne d’une activation de la voie PI3K/Akt freinant la lipolyse induite par le jeûne et favorisant ainsi le stockage des lipides et l’expansion du TA. Cette situation expérimentale est comparable à celle rencontrée au cours de l’obésité qui est associée à la fois, à une faible activité de la voie PI3K/Akt (résistance à l’insuline) et à une hyperactivation du SEC. Le blocage des CB1R par le Rimonabant chez la souris obèse, conduit à une stimulation importante de la lipolyse qui semble dépendre d’une activation de l’adénylate cyclase. Etant donné qu’un traitement par le Rimonabant s’accompagne également d’une augmentation du catabolisme des acides gras, il est raisonnable de penser que dans ces conditions, les AGL libérés n’exercent pas leurs effets délétères.En conclusion, ces travaux suggèrent que l’activation du SEC participe à l’installation d’une résistance à l’insuline dans le TA qui pourrait, à plus long terme, s’étendre aux tissus périphériques via les effets lipotoxiques des AGL issus de la lipolyse. Au cours de l’obésité, l’association d’une insulinorésistance et d’un tonus endocannabinoïde élevé favoriserait le stockage des lipides et l’expansion de la masse grasse. Au final, le blocage ciblé des CB1R du TA pourrait constituer une piste thérapeutique intéressante pour lutter contre les dérégulations métaboliques associées à l’obésité.Mots clés : Obésité, Insulinorésistance, Système Endocannabinoïde, Tissu Adipeux, Lipolyse, Métabolisme glucido-lipidique / Role of adipose tissue cannabinoid receptor 1 (CB1R) on lipolysis and consequences on lipid and carbohydrate metabolism in miceObesity is accompanied with lipolysis deregulation responsible for excessive Free Fatty Acid (FFA) release, which are key actors in the implementation of peripheral insulin resistance. In parallel, it is now well established that obesity is associated with EndoCannabinoid System (ECS) activity dysfunction in several metabolic tissues. If it is well described that overactivation of this system in the Adipose Tissue (AT) is favourable to its expansion, the consequences on lipolysis remain to be elucidated.The main objective of this thesis work was to precise the role of ECS on lipolysis regulation. To achieve this, AEA, a cannabinoid receptor 1 (CB1R) agonist and JZL195, an inhibitor of the enzymes responsible for the degradation of endocannabinoids, were used, in vivo in mice and in vitro on an explant model, to increase the endocannabinoid tone in the AT and analyse the consequences on lipolytic activity. Then, ECS blockade effect on lipolysis was studied in obese mice by using a specific CB1R antagonist, Rimonabant.This work demonstrates that activation of ECS under high insulinemia condition (postprandial state) alters insulin signalling limiting its antilipolytic effect and increasing FFA release which can ultimately be deleterious for peripheral tissues. Conversely, when insulin signalling pathways are weakly activated, as it is the case during fasting, ECS activation comes with PI3K/Akt activation impeding fasting induced lipolysis and promoting lipid storage and AT expansion. This experimental situation resembles that encountered in obesity which is associated, both with low activity of PI3K/Akt pathway (insulin resistance) and ECS overactivation. CB1R blockade by Rimonabant in obese mice lead to a strong stimulation of lipolysis which seems to be dependent on adenylate cyclase activation. Considering that Rimonabant treatment was also reported to be associated with improved fatty acid catabolism, it can be advanced that FFA released in excess in these conditions, do not have deleterious effects.In conclusion, this work suggests that ECS activation is involved in the onset of AT insulin resistance which ultimately could indirectly affect peripheral tissues via lipolysis derived FFA lipotoxicity. During obesity, the association of insulin resistance and ECS tone elevation would promote lipid storage and AT expansion. Finally, AT CB1R specific blockade could constitute an interesting therapeutic target limiting metabolic deregulations linked to obesity.Key words: Obesity, Insulin Resistance, Endocannabinoid System, Adipose Tissue, Lipolysis, Lipid and carbohydrate metabolism
19

Repercussões de variantes genéticas em componentes do sistema endocanabinoide e no receptor PPAR-&#945; sobre o perfil de risco cardiometabólico, adipocitocinas e níveis plasmáticos de endocanabinoides em indivíduos com diferentes graus de adiposidade / Effects of genetic variants in components of the endocannabinoid system and the PPAR-&#945; receptor on the cardiometabolic risk profile, adipocytokines and plasma endocannabinoid levels in subjects with varying degrees of adiposity

Cyro José de Moraes Martins 30 July 2013 (has links)
Analisar a associação recíproca entre fatores de risco cardiometabólico, níveis de adipocitocinas (leptina e adiponectina de alto peso molecular), endocanabinoides (anandamida [AEA] e 2-araquidonoilglicerol [2-AG]), compostos canabimiméticos (N-oleoiletanolamina [OEA] e N-palmitoiletanolamina [PEA]) e polimorfismos em genes codificadores de componentes do sistema endocanabinoide (enzima de degradação de endocanabinoides FAAH [gene FAAH] e receptor endocanabinoide CB1 [gene CNR1]) e do receptor PPAR-&#945; [gene PPARA], em indivíduos com diferentes graus de adiposidade. Duzentos indivíduos, entre 18 e 60 anos, com diferentes graus de índice de massa corporal (IMC) compuseram a amostra, dividida em dois grupos: cem eutróficos (IMC < 25 kg/m2) e 100 obesos (IMC &#8805; 30 kg/m2), com 50 homens e 50 mulheres em cada grupo. Os obesos ficaram assim distribuídos: grau 1, com IMC < 35 kg/m2 (n=54), 27 homens e 27 mulheres; grau 2, com IMC < 40 kg/m2 (n=32), 16 homens e 16 mulheres e grau 3, com IMC &#8805; 40 kg/m2 (n=14), 7 homens e 7 mulheres. Todos os indivíduos foram recrutados entre funcionários, estudantes e residentes do Hospital Universitário Pedro Ernesto, bem como voluntários do quadro da Polícia Militar do Estado do Rio de Janeiro e selecionados com base em amostra de conveniência. Todos foram avaliados por parâmetros antropométricos, determinação da pressão arterial, análises laboratoriais e genotipagem, para determinar seu perfil metabólico, níveis de endocanabinoides e adipocitocinas e rastreamento dos polimorfismos FAAH 385C>A, CNR1 3813A>G e PPARA 484C>G. Foram excluídos do estudo aqueles com história de comorbidades crônicas, doenças inflamatórias agudas, dependência de drogas de qualquer natureza e em uso de medicação nos dez dias anteriores à entrada no estudo. A atividade inflamatória, avaliada pela proteína C reativa ultrassensível (PCRUS), acompanhou o grau de resistência insulínica. Os níveis de PEA se associaram negativamente com a adiposidade visceral e resistência insulínica, sugerindo um melhor perfil metabólico, enquanto que os níveis de 2-AG se associaram positivamente com a PCRUS, apontando para piora nesse perfil. Os polimorfismos estudados não se associaram com o fenótipo obeso ou insulinorresistente. A presença do alelo 3813G no gene CNR1 mostrou associação independente com níveis reduzidos de adiponectina em obesos, sugerindo pior perfil metabólico nesse grupo. A presença do alelo 484G no gene PPARA, associando-se com níveis mais elevados de IMC e LDL-colesterol nos eutróficos pode indicar maior predisposição desses indivíduos para o desenvolvimento de obesidade e dislipidemia aterosclerótica. O genótipo homozigoto AA na posição 385 do gene FAAH e os níveis de PCRUS foram as principais associações, diretas e independentes, com os níveis de AEA, indicando claramente disfunção da enzima de degradação da AEA e, possivelmente, contribuindo para um perfil cardiometabólico mais vulnerável em portadores dessa variante genética. / To analyze the reciprocal association of cardiometabolic risk factors, levels of adipocytokines (leptin and high molecular weight adiponectin), endocannabinoids (anandamide [AEA] and 2-arachidonoylglycerol [2-AG]), cannabimimetic compounds (N-oleoylethanolamine [OEA] and N-palmitoylethanolamine [PEA]) and polymorphisms in genes encoding components of the endocannabinoid system (endocannabinoid degradation enzyme FAAH [FAAH gene] and endocannabinoid receptor CB1 [CNR1 gene]) and the PPAR-&#945; receptor (PPARA gene) in subjects with varying degrees of adiposity. Two hundred individuals between 18 and 60 years with varying degrees of body mass index (BMI) comprised the sample, divided in two groups: one hundred eutrophic (BMI < 25 kg/m2) and 100 obese (BMI &#8805; 30 kg/m2), 50 men and 50 women per group. The obese were distributed as follows: grade 1, with BMI < 35 kg/m2 (n = 54), 27 men and 27 women; grade 2, with BMI between &#8805; 35 and < 40 kg/m2 (n = 32), 16 men and 16 women and grade 3, with BMI &#8805; 40 kg/m2 (n = 14), 7 men and 7 women. All subjects were recruited from staff, students and residents of Pedro Ernesto University Hospital, as well as volunteers from Military Police of Rio de Janeiro State and selected based on a convenience sample. All were evaluated by anthropometric parameters, blood pressure determination, laboratory analysis and genotyping, to determine their metabolic profile, endocannabinoid and adipocytokine levels and investigate the polymorphisms FAAH 385C>A, CNR1 3813G>A and PPARA 484C>G. Those with a history of chronic comorbidities, acute inflammatory diseases, drug addiction of any kind and on medication in the ten days prior to study entry were withdrawn from the study. The inflammatory activity as assessed by high sensitive C reactive protein (hsCRP), accompanied the degree of insulin resistance. The levels of PEA negatively associated with visceral adiposity and insulin resistance, suggesting a better metabolic profile, whereas 2-AG levels were positively associated with hsCRP, pointing to a worse metabolic profile. The polymorphisms studied were not associated with the obese or insulin resistant phenotype. The presence of the allele 3813G in the CNR1 gene was independently associated with reduced levels of adiponectin in obese patients, suggesting a worse metabolic profile in this group. The presence of the allele 484G in the PPARA gene associating with higher levels of BMI and LDL-cholesterol in eutrophics may indicate a predisposition for the development of obesity and atherosclerotic dyslipidemia in these individuals. The homozygous genotype AA in position 385 of the FAAH gene, along with levels of hsCRP, were the main direct and independent associations with AEA levels, clearly indicating dysfunction of the degradation enzyme of AEA and possibly contributing to a more vulnerable cardiometabolic profile in individuals with this variant genotype.
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Repercussões de variantes genéticas em componentes do sistema endocanabinoide e no receptor PPAR-&#945; sobre o perfil de risco cardiometabólico, adipocitocinas e níveis plasmáticos de endocanabinoides em indivíduos com diferentes graus de adiposidade / Effects of genetic variants in components of the endocannabinoid system and the PPAR-&#945; receptor on the cardiometabolic risk profile, adipocytokines and plasma endocannabinoid levels in subjects with varying degrees of adiposity

Cyro José de Moraes Martins 30 July 2013 (has links)
Analisar a associação recíproca entre fatores de risco cardiometabólico, níveis de adipocitocinas (leptina e adiponectina de alto peso molecular), endocanabinoides (anandamida [AEA] e 2-araquidonoilglicerol [2-AG]), compostos canabimiméticos (N-oleoiletanolamina [OEA] e N-palmitoiletanolamina [PEA]) e polimorfismos em genes codificadores de componentes do sistema endocanabinoide (enzima de degradação de endocanabinoides FAAH [gene FAAH] e receptor endocanabinoide CB1 [gene CNR1]) e do receptor PPAR-&#945; [gene PPARA], em indivíduos com diferentes graus de adiposidade. Duzentos indivíduos, entre 18 e 60 anos, com diferentes graus de índice de massa corporal (IMC) compuseram a amostra, dividida em dois grupos: cem eutróficos (IMC < 25 kg/m2) e 100 obesos (IMC &#8805; 30 kg/m2), com 50 homens e 50 mulheres em cada grupo. Os obesos ficaram assim distribuídos: grau 1, com IMC < 35 kg/m2 (n=54), 27 homens e 27 mulheres; grau 2, com IMC < 40 kg/m2 (n=32), 16 homens e 16 mulheres e grau 3, com IMC &#8805; 40 kg/m2 (n=14), 7 homens e 7 mulheres. Todos os indivíduos foram recrutados entre funcionários, estudantes e residentes do Hospital Universitário Pedro Ernesto, bem como voluntários do quadro da Polícia Militar do Estado do Rio de Janeiro e selecionados com base em amostra de conveniência. Todos foram avaliados por parâmetros antropométricos, determinação da pressão arterial, análises laboratoriais e genotipagem, para determinar seu perfil metabólico, níveis de endocanabinoides e adipocitocinas e rastreamento dos polimorfismos FAAH 385C>A, CNR1 3813A>G e PPARA 484C>G. Foram excluídos do estudo aqueles com história de comorbidades crônicas, doenças inflamatórias agudas, dependência de drogas de qualquer natureza e em uso de medicação nos dez dias anteriores à entrada no estudo. A atividade inflamatória, avaliada pela proteína C reativa ultrassensível (PCRUS), acompanhou o grau de resistência insulínica. Os níveis de PEA se associaram negativamente com a adiposidade visceral e resistência insulínica, sugerindo um melhor perfil metabólico, enquanto que os níveis de 2-AG se associaram positivamente com a PCRUS, apontando para piora nesse perfil. Os polimorfismos estudados não se associaram com o fenótipo obeso ou insulinorresistente. A presença do alelo 3813G no gene CNR1 mostrou associação independente com níveis reduzidos de adiponectina em obesos, sugerindo pior perfil metabólico nesse grupo. A presença do alelo 484G no gene PPARA, associando-se com níveis mais elevados de IMC e LDL-colesterol nos eutróficos pode indicar maior predisposição desses indivíduos para o desenvolvimento de obesidade e dislipidemia aterosclerótica. O genótipo homozigoto AA na posição 385 do gene FAAH e os níveis de PCRUS foram as principais associações, diretas e independentes, com os níveis de AEA, indicando claramente disfunção da enzima de degradação da AEA e, possivelmente, contribuindo para um perfil cardiometabólico mais vulnerável em portadores dessa variante genética. / To analyze the reciprocal association of cardiometabolic risk factors, levels of adipocytokines (leptin and high molecular weight adiponectin), endocannabinoids (anandamide [AEA] and 2-arachidonoylglycerol [2-AG]), cannabimimetic compounds (N-oleoylethanolamine [OEA] and N-palmitoylethanolamine [PEA]) and polymorphisms in genes encoding components of the endocannabinoid system (endocannabinoid degradation enzyme FAAH [FAAH gene] and endocannabinoid receptor CB1 [CNR1 gene]) and the PPAR-&#945; receptor (PPARA gene) in subjects with varying degrees of adiposity. Two hundred individuals between 18 and 60 years with varying degrees of body mass index (BMI) comprised the sample, divided in two groups: one hundred eutrophic (BMI < 25 kg/m2) and 100 obese (BMI &#8805; 30 kg/m2), 50 men and 50 women per group. The obese were distributed as follows: grade 1, with BMI < 35 kg/m2 (n = 54), 27 men and 27 women; grade 2, with BMI between &#8805; 35 and < 40 kg/m2 (n = 32), 16 men and 16 women and grade 3, with BMI &#8805; 40 kg/m2 (n = 14), 7 men and 7 women. All subjects were recruited from staff, students and residents of Pedro Ernesto University Hospital, as well as volunteers from Military Police of Rio de Janeiro State and selected based on a convenience sample. All were evaluated by anthropometric parameters, blood pressure determination, laboratory analysis and genotyping, to determine their metabolic profile, endocannabinoid and adipocytokine levels and investigate the polymorphisms FAAH 385C>A, CNR1 3813G>A and PPARA 484C>G. Those with a history of chronic comorbidities, acute inflammatory diseases, drug addiction of any kind and on medication in the ten days prior to study entry were withdrawn from the study. The inflammatory activity as assessed by high sensitive C reactive protein (hsCRP), accompanied the degree of insulin resistance. The levels of PEA negatively associated with visceral adiposity and insulin resistance, suggesting a better metabolic profile, whereas 2-AG levels were positively associated with hsCRP, pointing to a worse metabolic profile. The polymorphisms studied were not associated with the obese or insulin resistant phenotype. The presence of the allele 3813G in the CNR1 gene was independently associated with reduced levels of adiponectin in obese patients, suggesting a worse metabolic profile in this group. The presence of the allele 484G in the PPARA gene associating with higher levels of BMI and LDL-cholesterol in eutrophics may indicate a predisposition for the development of obesity and atherosclerotic dyslipidemia in these individuals. The homozygous genotype AA in position 385 of the FAAH gene, along with levels of hsCRP, were the main direct and independent associations with AEA levels, clearly indicating dysfunction of the degradation enzyme of AEA and possibly contributing to a more vulnerable cardiometabolic profile in individuals with this variant genotype.

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