RESUMO
Lysophosphatidic acid (LPA) is the natural ligand for two phylogenetically distinct families of receptors (LPA1-3, LPA4-6) whose pathways control a variety of physiologic and pathophysiological responses. Identifying the benefit of balanced activation/repression of LPA receptors has always been a challenge because of the high lability of LPA and the limited availability of selective and/or stable agonists. In this study, we document the discovery of small benzofuran ethanolamine derivatives (called CpX and CpY) behaving as LPA1-3 agonists. Initially found as rabbit urethra contracting agents, their elusive receptors were identified from [35S]GTPγS-binding and ß-arrestin2 recruitment investigations and then confirmed by [3H]CpX binding studies (urethra, hLPA1-2 membranes). Both compounds induced a calcium response in hLPA1-3 cells within a range of 0.4-1.5-log lower potency as compared with LPA. The contractions of rabbit urethra strips induced by these compounds perfectly matched binding affinities with values reaching the two-digit nanomolar level. The antagonist, KI16425, dose-dependently antagonized CpX-induced contractions in agreement with its affinity profile (LPA1≥LPA3>>LPA2). The most potent agonist, CpY, doubled intraurethral pressure in anesthetized female rats at 3 µg/kg i.v. Alternatively, CpX was shown to inhibit human preadipocyte differentiation, a process totally reversed by KI16425. Together with original molecular docking data, these findings clearly established these molecules as potent agonists of LPA1-3 and consolidated the pivotal role of LPA1 in urethra/prostate contraction as well as in fat cell development. The discovery of these unique and less labile LPA1-3 agonists would offer new avenues to investigate the roles of LPA receptors. SIGNIFICANCE STATEMENT: We report the identification of benzofuran ethanolamine derivatives behaving as potent selective nonlipid LPA1-3 agonists and shown to alter urethra muscle contraction or preadipocyte differentiation. Unique at this level of potency, selectivity, and especially stability, compared with lysophosphatidic acid, they represent more appropriate tools for investigating the physiological roles of lysophosphatidic acid receptors and starting point for optimization of drug candidates for therapeutic applications.
Assuntos
Benzofuranos/química , Benzofuranos/farmacologia , Descoberta de Drogas , Etanolamina/química , Receptores de Ácidos Lisofosfatídicos/agonistas , Adipócitos/citologia , Adipócitos/efeitos dos fármacos , Animais , Benzofuranos/metabolismo , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Células CHO , Diferenciação Celular/efeitos dos fármacos , Cricetulus , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Humanos , Simulação de Acoplamento Molecular , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Músculo Liso/fisiologia , Conformação Proteica , Coelhos , Ratos , Receptores de Ácidos Lisofosfatídicos/química , Receptores de Ácidos Lisofosfatídicos/metabolismo , beta-Arrestina 2/metabolismoRESUMO
Therapeutic antibodies targeting proprotein convertase subtilisin kexin type 9 (PCSK9) (e.g. alirocumab) lower low-density lipoprotein cholesterol (LDL-C) and lipoprotein (a) [Lp(a)] levels in clinical trials. We recently showed that PCSK9 enhances apolipoprotein(a) [apo(a)] secretion from primary human hepatocytes but does not affect Lp(a) cellular uptake. Here, we aimed to determine how PCSK9 neutralization modulates Lp(a) levels in vivoSix nonhuman primates (NHP) were treated with alirocumab or a control antibody (IgG1) in a crossover protocol. After the lowering of lipids reached steady state, NHP received an intravenous injection of [2H3]-leucine, and blood samples were collected sequentially over 48 h. Enrichment of apolipoproteins in [2H3]-leucine was assessed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Kinetic parameters were calculated using numerical models with the SAAMII software. Compared with IgG1, alirocumab significantly reduced total cholesterol (TC) (-28%), LDL-C (-67%), Lp(a) (-56%), apolipoprotein B100 (apoB100) (-53%), and apo(a) (-53%). Alirocumab significantly increased the fractional catabolic rate of apoB100 (+29%) but not that of apo(a). Conversely, alirocumab sharply and significantly reduced the production rate (PR) of apo(a) (-42%), but not significantly that of apoB100, compared with IgG1, respectively.In line with the observations made in human hepatocytes, the present kinetic study establishes that PCSK9 neutralization with alirocumab efficiently reduces circulating apoB100 and apo(a) levels by distinct mechanisms: apoB primarily by enhancing its catabolism and apo(a) primarily by lowering its production.
Assuntos
Anticorpos Monoclonais/farmacologia , Anticolesterolemiantes/farmacologia , Lipoproteína(a)/sangue , Inibidores de PCSK9 , Animais , Anticorpos Monoclonais Humanizados , Apoproteína(a)/biossíntese , Colesterol/sangue , Estudos Cross-Over , Feminino , Lipídeos/sangue , Macaca fascicularis , MasculinoRESUMO
Since 2012, clinical trials dedicated to proprotein convertase subtilisin kexin type 9 (PCSK9) inhibition with monoclonal antibodies (mAbs) have unambiguously demonstrated robust reductions not only in low-density lipoprotein (LDL) cholesterol (LDL-C) but also in lipoprotein (a) [Lp(a)] levels. The scientific literature published prior to those studies did not provide any evidence for a link between PCSK9 and Lp(a) metabolism. More recent investigations, either in vitro or in vivo, have attempted to unravel the mechanism(s) by which PCSK9 mAbs reduce circulating Lp(a) levels, with some showing a specific implication of the LDL receptor (LDLR) in Lp(a) clearance whereas others found no significant role for the LDLR in that process. This elusive pathway appears clearly distinct from that of the widely prescribed statins that also enhance LDLR function but do not lower circulating Lp (a) levels in humans. So how does PCSK9 inhibition with mAbs reduce Lp(a)? This still remains to be established.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Hiperlipidemias/tratamento farmacológico , Lipoproteína(a)/sangue , Inibidores de PCSK9 , Anticorpos Monoclonais/farmacologia , Anticorpos Monoclonais Humanizados , Humanos , Hiperlipidemias/sangue , Hipolipemiantes/farmacologia , Hipolipemiantes/uso terapêutico , Pró-Proteína Convertase 9/imunologia , Receptores de LDL/fisiologia , Projetos de PesquisaRESUMO
Chemical modulation of a formerly disclosed DGAT-1 inhibitor resulted in the identification of a compound with a suitable profile for preclinical development. Optimisation of solubility is discussed and a PK/PD study is presented.
Assuntos
Diacilglicerol O-Aciltransferase/antagonistas & inibidores , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Oxidiazóis/farmacologia , Tiadiazóis/farmacologia , Diacilglicerol O-Aciltransferase/metabolismo , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/química , Humanos , Modelos Moleculares , Estrutura Molecular , Oxidiazóis/síntese química , Oxidiazóis/química , Relação Estrutura-Atividade , Tiadiazóis/síntese química , Tiadiazóis/químicaRESUMO
BACKGROUND: The lack of disease-modifying drugs is one of the major unmet needs in patients with heart failure (HF). Peptides are highly selective molecules with the potential to act directly on cardiomyocytes. However, a strategy for effective delivery of therapeutics to the heart is lacking. OBJECTIVES: In this study, the authors sought to assess tolerability and efficacy of an inhalable lung-to-heart nano-in-micro technology (LungToHeartNIM) for cardiac-specific targeting of a mimetic peptide (MP), a first-in-class for modulating impaired L-type calcium channel (LTCC) trafficking, in a clinically relevant porcine model of HF. METHODS: Heart failure with reduced ejection fraction (HFrEF) was induced in Göttingen minipigs by means of tachypacing over 6 weeks. In a setting of overt HFrEF (left ventricular ejection fraction [LVEF] 30% ± 8%), animals were randomized and treatment was started after 4 weeks of tachypacing. HFrEF animals inhaled either a dry powder composed of mannitol-based microparticles embedding biocompatible MP-loaded calcium phosphate nanoparticles (dpCaP-MP) or the LungToHeartNIM only (dpCaP without MP). Efficacy was evaluated with the use of echocardiography, invasive hemodynamics, and biomarker assessment. RESULTS: DpCaP-MP inhalation restored systolic function, as shown by an absolute LVEF increase over the treatment period of 17% ± 6%, while reversing cardiac remodeling and reducing pulmonary congestion. The effect was recapitulated ex vivo in cardiac myofibrils from treated HF animals. The treatment was well tolerated, and no adverse events occurred. CONCLUSIONS: The overall tolerability of LungToHeartNIM along with the beneficial effects of the LTCC modulator point toward a game-changing treatment for HFrEF patients, also demonstrating the effective delivery of a therapeutic peptide to the diseased heart.
Assuntos
Insuficiência Cardíaca , Animais , Doença Crônica , Pulmão , Peptídeos , Volume Sistólico , Suínos , Porco Miniatura , Função Ventricular EsquerdaRESUMO
This Letter describes the asymmetric synthesis of the four stereoisomers (8a-8d) of a potent and highly selective histamine H3 receptor (H3R) antagonist, 5-fluoro-2-methyl-N-[2-methyl-4-(2-methyl[1,3']bipyrrolidinyl-1'-yl) phenyl]benzamide (1). The physico-chemical properties, in vitro H3R affinities and ADME of 8a-8d were determined. Stereoisomer 8c (2S,3'S) displayed superior in vitro H3R affinity over other three stereoisomers and was selected for further profiling in in vivo PK and drug safety. Compound 8c exhibited excellent PK properties with high exposure, desired brain to plasma ratio and reasonable brain half life. However, all stereoisomers showed similar unwanted hERG affinities.
Assuntos
Benzamidas/química , Benzamidas/síntese química , Antagonistas dos Receptores Histamínicos/síntese química , Pirrolidinas/síntese química , Receptores Histamínicos H3/química , Animais , Benzamidas/farmacocinética , Encéfalo/metabolismo , Meia-Vida , Antagonistas dos Receptores Histamínicos/química , Antagonistas dos Receptores Histamínicos/farmacocinética , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microssomos Hepáticos/metabolismo , Pirrolidinas/química , Pirrolidinas/farmacocinética , Ratos , Receptores Histamínicos H3/metabolismo , EstereoisomerismoRESUMO
A series of structurally novel aryl ureas was derived from optimization of the HTS lead as selective histamine H3 receptor (H3R) antagonists. The SAR was explored and the data obtained set up the starting point and foundation for further optimization. The most potent tool compounds, as exemplified by compounds 2l, 5b, 5d, and 5e, displayed antagonism potencies in the subnanomolar range in in vitro human-H3R FLIPR assays and rhesus monkey H3R binding assays.
Assuntos
Amidas/química , Antagonistas dos Receptores Histamínicos H3/química , Receptores Histamínicos H3/química , Ureia/química , Amidas/metabolismo , Amidas/uso terapêutico , Animais , Avaliação Pré-Clínica de Medicamentos , Células HEK293 , Antagonistas dos Receptores Histamínicos H3/metabolismo , Antagonistas dos Receptores Histamínicos H3/uso terapêutico , Humanos , Macaca mulatta , Obesidade/tratamento farmacológico , Ligação Proteica , Ratos , Receptores Histamínicos H3/genética , Receptores Histamínicos H3/metabolismo , Relação Estrutura-Atividade , Ureia/metabolismo , Ureia/uso terapêuticoRESUMO
A novel series of histamine H3 receptor (H3R) antagonists was derived from an arylurea lead series (1) via bioisosteric replacement of the urea functionality by an amide linkage. The arylamide series was optimized through SAR studies by a broad variation of substituents in the left-hand side benzoyl residue (analogs 2a-2ag) or replacement of the benzoyl moiety by heteroarylcarbonyl residues (analogs 5a-5n). Compounds 2p and 2q were identified within the series as potent and selective H3R antagonists/inverse agonists with acceptable overall profile. Compound 2q was orally active in food intake inhibition in diet-induced obese (DIO) mice. Compound 2q represents a novel H3R antagonist template with improved in vitro potency and oral efficacy and has its merits as a new lead for further optimization.
Assuntos
Amidas/química , Benzamidas/química , Antagonistas dos Receptores Histamínicos H3/química , Pirrolidinas/química , Receptores Histamínicos H3/química , Ureia/química , Administração Oral , Amidas/metabolismo , Amidas/uso terapêutico , Animais , Benzamidas/metabolismo , Benzamidas/uso terapêutico , Células CACO-2 , Avaliação Pré-Clínica de Medicamentos , Agonismo Inverso de Drogas , Antagonistas dos Receptores Histamínicos H3/metabolismo , Antagonistas dos Receptores Histamínicos H3/uso terapêutico , Humanos , Camundongos , Microssomos/metabolismo , Obesidade/tratamento farmacológico , Ligação Proteica , Pirrolidinas/metabolismo , Pirrolidinas/uso terapêutico , Ratos , Receptores Histamínicos H3/genética , Receptores Histamínicos H3/metabolismo , Relação Estrutura-Atividade , Ureia/metabolismo , Ureia/uso terapêuticoRESUMO
Starting from 11ß-HSD1 inhibitors that were active ex vivo but with Cyp 3A4 liability, we obtained a new series of adamantane ureas displaying potent inhibition of both human and rodent 11ß-HSD1 enzymes, devoid of Cyp 3A4 interactions, and rationally designed to provide long-lasting inhibition in target tissues. Final optimizations lead to SAR184841 with good oral pharmacokinetic properties showing in vivo activity and improvement of metabolic parameters in a physiopathological model of type 2 diabetes.
Assuntos
11-beta-Hidroxiesteroide Desidrogenase Tipo 1/antagonistas & inibidores , Adamantano/farmacologia , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Tipo 2/tratamento farmacológico , 11-beta-Hidroxiesteroide Desidrogenase Tipo 1/metabolismo , Adamantano/química , Adamantano/farmacocinética , Animais , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Modelos Animais de Doenças , Humanos , Camundongos , Camundongos Transgênicos , Relação Estrutura-AtividadeRESUMO
A novel class of DGAT1 inhibitors containing a thiadiazole core has been discovered. Chemical optimization lead to inhibitors of human DGAT1 with an appropriate ADME profile and that show in vivo activity in target tissues.
Assuntos
Diacilglicerol O-Aciltransferase/antagonistas & inibidores , Inibidores Enzimáticos/síntese química , Hipoglicemiantes/síntese química , Tiadiazóis/síntese química , Triglicerídeos/antagonistas & inibidores , Células CACO-2 , Ensaios Clínicos como Assunto , Diacilglicerol O-Aciltransferase/metabolismo , Descoberta de Drogas , Inibidores Enzimáticos/farmacologia , Humanos , Hipoglicemiantes/farmacologia , Modelos Moleculares , Estereoisomerismo , Relação Estrutura-Atividade , Tiadiazóis/farmacologia , Triglicerídeos/biossínteseRESUMO
There is growing evidence that apelin plays a role in the regulation of the cardiovascular system by increasing myocardial contractility and acting as a vasodilator. However, it remains unclear whether apelin improves cardiac contractility in a load-dependent or independent manner in pathological conditions. For this purpose we investigated the cardiovascular effects of apelin in α-actin transgenic mice (mActin-Tg mice), a model of cardiomyopathy. [Pyr1]apelin-13 was administered by continuous infusion at 2 mg/kg/d for 3 weeks. Effects on cardiac function were determined by echocardiography and a Pressure-Volume (PV) analysis. mActin-Tg mice showed a dilated cardiomyopathy (DCM) phenotype similar to that encountered in patients expressing the same mutation. Compared to WT animals, mActin-Tg mice displayed cardiac systolic impairment [significant decrease in ejection fraction (EF), cardiac output (CO), and stroke volume (SV)] associated with cardiac ventricular dilation and diastolic dysfunction, characterized by an impairment in mitral flow velocity (E/A) and in deceleration time (DT). Load-independent myocardial contractility was strongly decreased in mActin-Tg mice while total peripheral vascular resistance (TPR) was significantly increased. As compared to vehicle-treated animals, a 3-week treatment with [Pyr1]apelin-13 significantly improved EF%, SV, E/A, DT and corrected TPR, with no significant effect on load-independent indices of myocardial contractility, blood pressure and heart rate. In conclusion [Pyr1]apelin-13 displayed no intrinsic contractile effect but improved cardiac function in dilated cardiomyopathy mainly by reducing peripheral vascular resistance, with no change in blood pressure.
Assuntos
Apelina/farmacologia , Cardiomiopatia Dilatada/tratamento farmacológico , Doenças Vasculares Periféricas/prevenção & controle , Resistência Vascular , Vasodilatação , Animais , Pressão Sanguínea , Cardiomiopatia Dilatada/patologia , Modelos Animais de Doenças , Frequência Cardíaca , Humanos , Camundongos , Camundongos Transgênicos , Doenças Vasculares Periféricas/patologia , Volume SistólicoRESUMO
BACKGROUND AND AIMS: The YAP/TAZ signaling is known to regulate endothelial activation and vascular inflammation in response to shear stress. Moreover, YAP/TAZ signaling plays a role in the progression of cancers and renal damage associated with diabetes. However, whether YAP/TAZ signaling is also implicated in diabetes-associated vascular complications is not known. METHODS: The effect of high glucose on YAP/TAZ signaling was firstly evaluated in vitro on endothelial cells cultured under static conditions or subjected to shear stress (either laminar or oscillatory flow). The impact of diabetes on YAP/TAZ signaling was additionally assessed in vivo in db/db mice. RESULTS: In vitro, we found that YAP was dephosphorylated/activated by high glucose in endothelial cells, thus leading to increased endothelial inflammation and monocyte attachment. Moreover, YAP was further activated when high glucose was combined to laminar flow conditions. YAP was also activated by oscillatory flow conditions but, in contrast, high glucose did not exert any additional effect. Interestingly, inhibition of YAP reduced endothelial inflammation and monocyte attachment. Finally, we found that YAP is also activated in the vascular wall of diabetic mice, where inflammatory markers are also increased. CONCLUSION: With the current study we demonstrated that YAP signaling is activated by high glucose in endothelial cells in vitro and in the vasculature of diabetic mice, and we pinpointed YAP as a regulator of high glucose-mediated endothelial inflammation and monocyte attachment. YAP inhibition may represent a potential therapeutic opportunity to improve diabetes-associated vascular complications.
RESUMO
Lipoprotein(a) (Lp[a]) is the most common genetically inherited risk factor for cardiovascular disease. Many aspects of Lp(a) metabolism remain unknown. We assessed the uptake of fluorescent Lp(a) in primary human lymphocytes as well as Lp(a) hepatic capture in a mouse model in which endogenous hepatocytes have been ablated and replaced with human ones. Modulation of LDLR expression with the PCSK9 inhibitor alirocumab did not alter the cellular or the hepatic uptake of Lp(a), demonstrating that the LDL receptor is not a major route for Lp(a) plasma clearance. These results have clinical implications because they underpin why statins are not efficient at reducing Lp(a).
RESUMO
Therapeutic antibodies (Abs) are emerging as major drugs to treat respiratory diseases, and inhalation may provide substantial benefits for their delivery. Understanding the behavior of Abs after pulmonary deposition is critical for their development. We investigated the pharmacokinetics of a nebulized Ab by continuous sampling in lung parenchyma using microdialysis in non-human primates. We defined the optimal conditions for microdialysis of Ab and demonstrated that lung microdialysis of Ab is feasible over a period of several days. The concentration-profile indicated a two-phase non-linear elimination and/or distribution of inhaled mAbX. Lung exposition was higher than the systemic one over a period of 33 hours and above MabX affinity for its target. The microdialysis results were supported by an excellent relationship with dosages from lung extracts.
Assuntos
Anticorpos Monoclonais/farmacocinética , Pulmão/efeitos dos fármacos , Microdiálise/métodos , Administração por Inalação , Animais , Feminino , Macaca fascicularisRESUMO
To elucidate how the proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitor alirocumab modulates lipoprotein(a) [Lp(a)] plasma levels, the authors performed a series of Lp(a) uptake studies in primary human hepatocytes and dermal fibroblasts and measured Lp(a) secretion from human hepatocytes. They found that Lp(a) cellular uptake occurred in a low-density lipoprotein receptor-independent manner. Neither PCSK9 nor alirocumab altered Lp(a) internalization. By contrast, the secretion of apolipoprotein (a) from human hepatocytes was sharply increased by PCSK9, an effect that was reversed by alirocumab. They propose that PCSK9 does not significantly modulate Lp(a) catabolism, but rather enhances the secretion of Lp(a) from liver cells.
RESUMO
Central and peripheral mechanisms modulate food intake and energy balance in mammals and the precise role of the type 1 cannabinoid receptor (CB1) in these processes is still being explored. Using the zebrafish, Danio rerio, we show that rimonabant, a CB1-specific antagonist with an EC(50) of 5.15 × 10(-8) m, decreases embryonic yolk sac reserve use. We reveal a developmental overlap between CART genes and CB1 expression in the hypothalamus and medulla oblongata, two brain structures that play crucial roles in appetite regulation in mammals. We show that morpholino knockdown of CB1 or fasting decreases cocaine- and amphetamine-related transcript (CART)-3 expression. Strikingly, this down-regulation occurs only in regions coexpressing CB1 and CART3, reinforcing the link between CB1, CART, and appetite regulation. We show that rimonabant treatment impairs the fasting-induced down-regulation of CART expression in specific brain regions, whereas vehicle alone-treated embryos do not display this rescue of CART expression. Our data reveal that CB1 lies upstream of CART and signals the appetite through the down-regulation of CART expression. Thus, our results establish the zebrafish as a promising system to study appetite regulation.
Assuntos
Regulação do Apetite , Encéfalo/metabolismo , Regulação para Baixo , Privação de Alimentos , Receptor CB1 de Canabinoide/metabolismo , Peixe-Zebra/metabolismo , Animais , Encéfalo/embriologia , Agonistas de Receptores de Canabinoides/farmacologia , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Silenciamento de Genes , Larva/metabolismo , Dados de Sequência Molecular , Obesidade/metabolismo , Obesidade/fisiopatologia , Piperidinas/farmacologia , Pirazóis/farmacologia , Receptor CB1 de Canabinoide/agonistas , Receptor CB1 de Canabinoide/genética , Receptor CB2 de Canabinoide/genética , Receptor CB2 de Canabinoide/metabolismo , Rimonabanto , Saco Vitelino/metabolismo , Peixe-Zebra/genética , Peixe-Zebra/fisiologiaRESUMO
SAR110894 is a novel histamine H3-R ligand, displaying high and selective affinity for human, rat or mouse H3-Rs. SAR110894 is a potent H3-R antagonist at native receptors, reversing R-α-methylhistamine-induced inhibition of electrical field stimulation contraction in the guinea-pig ileum. Additionally, SAR110894 inhibited constitutive GTPγS binding at human H3-Rs demonstrating inverse agonist properties. In behavioral models addressing certain aspects of cognitive impairment associated with schizophrenia (CIAS) and attention deficit/hyperactivity disorder (ADHD), SAR110894 improved memory performances in several variants of the object recognition task in mice (0.3-3 mg/kg, p.o.) or rats (0.3-1 mg/kg, p.o.). Moreover, SAR110894 (1 mg/kg, p.o.) reversed a deficit in working memory in the Y-maze test, following an acute low dose of phencyclidine (PCP) (0.5 mg/kg, i.p.) in mice sensitized by repeated treatment with a high dose of PCP (10 mg/kg, i.p.). In the latent inhibition (LI) model, SAR110894 potentiated LI in saline-treated rats (1 and 3 mg/kg, i.p.) and reversed abnormally persistent LI induced by neonatal nitric oxide synthase (NOS) inhibition in rodents (0.3-3 mg/kg, i.p.). In a social novelty discrimination task in rats, SAR110894 attenuated selective attention deficit induced by neonatal PCP treatment (3 and 10 mg/kg, p.o.) or a parametric modification of the procedure (3 and 10 mg/kg, p.o.). SAR110894 showed efficacy in several animal models related to the cognitive deficits in Alzheimer's disease (AD). It prevented the occurrence of episodic memory deficit induced by scopolamine in rats (0.01-10 mg/kg, p.o.) or by the central infusion of the toxic amyloid fragment ß25â35 in the object recognition test in mice (1 and 3 mg/kg, p.o.). Altogether, these findings suggest that SAR110894 may be of therapeutic interest for the treatment of the cognitive symptoms of AD, schizophrenia and certain aspects of ADHD.
Assuntos
Cognição/efeitos dos fármacos , Antagonistas dos Receptores Histamínicos H3/farmacologia , Animais , Feminino , Antagonistas dos Receptores Histamínicos H3/uso terapêutico , Aprendizagem em Labirinto , Camundongos , Ratos , Ratos Sprague-Dawley , Ratos Wistar , Esquizofrenia/tratamento farmacológicoRESUMO
Cannabinoid receptor CB1 is expressed abundantly in the brain and presumably in the peripheral tissues responsible for energy metabolism. It is unclear if the antiobesity effects of rimonabant, a CB1 antagonist, are mediated through the central or the peripheral CB1 receptors. To address this question, we generated transgenic mice with central nervous system (CNS)-specific knockdown (KD) of CB1, by expressing an artificial microRNA (AMIR) under the control of the neuronal Thy1.2 promoter. In the mutant mice, CB1 expression was reduced in the brain and spinal cord, whereas no change was observed in the superior cervical ganglia (SCG), sympathetic trunk, enteric nervous system, and pancreatic ganglia. In contrast to the neuronal tissues, CB1 was undetectable in the brown adipose tissue (BAT) or the liver. Consistent with the selective loss of central CB1, agonist-induced hypothermia was attenuated in the mutant mice, but the agonist-induced delay of gastrointestinal transit (GIT), a primarily peripheral nervous system-mediated effect, was not. Compared to wild-type (WT) littermates, the mutant mice displayed reduced body weight (BW), adiposity, and feeding efficiency, and when fed a high-fat diet (HFD), showed decreased plasma insulin, leptin, cholesterol, and triglyceride levels, and elevated adiponectin levels. Furthermore, the therapeutic effects of rimonabant on food intake (FI), BW, and serum parameters were markedly reduced and correlated with the degree of CB1 KD. Thus, KD of CB1 in the CNS recapitulates the metabolic phenotype of CB1 knockout (KO) mice and diminishes rimonabant's efficacy, indicating that blockade of central CB1 is required for rimonabant's antiobesity actions.
Assuntos
Fármacos Antiobesidade/farmacologia , Peso Corporal/efeitos dos fármacos , Sistema Nervoso Central/metabolismo , Ingestão de Energia/efeitos dos fármacos , Obesidade/metabolismo , Piperidinas/farmacologia , Pirazóis/farmacologia , Receptor CB1 de Canabinoide/metabolismo , Adiponectina/sangue , Adiposidade/efeitos dos fármacos , Adiposidade/genética , Animais , Fármacos Antiobesidade/uso terapêutico , Biomarcadores/sangue , Peso Corporal/genética , Sistema Nervoso Central/efeitos dos fármacos , Colesterol/sangue , Dieta Hiperlipídica/efeitos adversos , Ingestão de Energia/genética , Trânsito Gastrointestinal/fisiologia , Hipotermia/prevenção & controle , Insulina/sangue , Leptina/sangue , Camundongos , Camundongos Knockout , Camundongos Transgênicos , MicroRNAs , Mutação , Obesidade/tratamento farmacológico , Obesidade/genética , Sistema Nervoso Periférico/efeitos dos fármacos , Sistema Nervoso Periférico/metabolismo , Fenótipo , Piperidinas/uso terapêutico , Regiões Promotoras Genéticas , Pirazóis/uso terapêutico , Receptor CB1 de Canabinoide/genética , Rimonabanto , Triglicerídeos/sangueRESUMO
The increase in adiponectin levels in obese patients with untreated dyslipidemia and its mRNA expression in adipose tissue of obese animals are one of the most interesting consequences of rimonabant treatment. Thus, part of rimonabant's metabolic effects could be related to an enhancement of adiponectin secretion and its consequence on the modulation of insulin action, as well as energy homeostasis. The present study investigated the effects of rimonabant in adiponectin knockout mice (Ad(-/-)) exposed to diet-induced obesity conditions. Six-week-old Ad(-/-) male mice and their wild-type littermate controls (Ad(+/+)) were fed a high-fat diet for 7 mo. During the last month, animals were administered daily either with vehicle or rimonabant by mouth (10 mg/kg). High-fat feeding induced weight gain by about 130% in both wild-type and Ad(-/-) mice. Obesity was associated with hyperinsulinemia and insulin resistance. Treatment with rimonabant led to a significant and similar decrease in body weight in both Ad(+/+) and Ad(-/-) mice compared with vehicle-treated animals. In addition, rimonabant significantly improved insulin sensitivity in Ad(+/+) mice compared with Ad(+/+) vehicle-treated mice by decreasing hepatic glucose production and increasing glucose utilization index in both visceral and subcutaneous adipose tissue. In contrast, rimonabant failed to improve insulin sensitivity in Ad(-/-) mice, despite the loss in body weight. Rimonabant's effect on body weight appeared independent of the adiponectin pathway, whereas adiponectin seems required to mediate rimonabant-induced improvement of insulin sensitivity in rodents.
Assuntos
Fármacos Antiobesidade/farmacologia , Hiperinsulinismo/prevenção & controle , Resistência à Insulina , Obesidade/tratamento farmacológico , Piperidinas/farmacologia , Pirazóis/farmacologia , Redução de Peso/efeitos dos fármacos , Adiponectina/deficiência , Adiponectina/genética , Adiponectina/metabolismo , Animais , Gorduras na Dieta , Modelos Animais de Doenças , Ingestão de Alimentos/efeitos dos fármacos , Glucose/metabolismo , Teste de Tolerância a Glucose , Hiperinsulinismo/etiologia , Hiperinsulinismo/metabolismo , Hiperinsulinismo/fisiopatologia , Insulina/sangue , Gordura Intra-Abdominal/efeitos dos fármacos , Gordura Intra-Abdominal/metabolismo , Lipídeos/sangue , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Camundongos Knockout , Obesidade/etiologia , Obesidade/metabolismo , Obesidade/fisiopatologia , Rimonabanto , Gordura Subcutânea/efeitos dos fármacos , Gordura Subcutânea/metabolismoRESUMO
The mechanisms by which the CB1 receptor antagonist rimonabant exerts its appetite-suppressing and energy-dissipating effects are still incompletely resolved. To shed further light on the central pathways influenced by CB1 receptor modulation we examined the expression of the immediate early gene c-fos in male Sprague-Dawley rats at 60, 120 and 240 min after intraperitoneal administration of the CB1R antagonist rimonabant (10 mg/kg) and the CB1R agonist WIN55,212-2 (3 mg/kg). Perfusion-fixed brains were processed for immunohistochemistry and the localization of c-Fos immunoreactive neuronal profiles was assessed qualitatively throughout the brain. Nine areas, including specific hypothalamic and brainstem nuclei known to be involved in appetite regulation, were selected for quantitative analyses. Whereas WIN55,212-2 induced c-Fos immunoreactivity in a time-specific manner in the striatum, the central nucleus of amygdala, the hypothalamic paraventricular nucleus and the arcuate nucleus, no significant increases in c-Fos positive nuclei were found in any forebrain areas following rimonabant administration. In contrast, rimonabant and WIN55,212-2 were both found to significantly increase c-Fos immunoreactivity in the brainstem lateral parabrachial nucleus, the nucleus of the solitary tract and the area postrema. To characterize the phenotype of activated neurons in the nucleus of the solitary tract, a triple immunohistochemical staining technique was used to simultaneously label c-Fos protein and tyrosine hydroxylase (TH), GLP-1 or CART. Interestingly, rimonabant was found to significantly increase c-Fos protein expression in TH-positive neurons. Collectively, these results suggest that brainstem areas including ascending catetholaminergic A2/C2 neurons could play a role in rimonabant-induced inhibition of food intake.