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1.
Proc Natl Acad Sci U S A ; 119(48): e2119824119, 2022 11 29.
Artigo em Inglês | MEDLINE | ID: mdl-36409897

RESUMO

Fatty acids are vital for the survival of eukaryotes, but when present in excess can have deleterious consequences. The AMP-activated protein kinase (AMPK) is an important regulator of multiple branches of metabolism. Studies in purified enzyme preparations and cultured cells have shown that AMPK is allosterically activated by small molecules as well as fatty acyl-CoAs through a mechanism involving Ser108 within the regulatory AMPK ß1 isoform. However, the in vivo physiological significance of this residue has not been evaluated. In the current study, we generated mice with a targeted germline knock-in (KI) mutation of AMPKß1 Ser108 to Ala (S108A-KI), which renders the site phospho-deficient. S108A-KI mice had reduced AMPK activity (50 to 75%) in the liver but not in the skeletal muscle. On a chow diet, S108A-KI mice had impairments in exogenous lipid-induced fatty acid oxidation. Studies in mice fed a high-fat diet found that S108A-KI mice had a tendency for greater glucose intolerance and elevated liver triglycerides. Consistent with increased liver triglycerides, livers of S108A-KI mice had reductions in mitochondrial content and respiration that were accompanied by enlarged mitochondria, suggestive of impairments in mitophagy. Subsequent studies in primary hepatocytes found that S108A-KI mice had reductions in palmitate- stimulated Cpt1a and Ppargc1a mRNA, ULK1 phosphorylation and autophagic/mitophagic flux. These data demonstrate an important physiological role of AMPKß1 Ser108 phosphorylation in promoting fatty acid oxidation, mitochondrial biogenesis and autophagy under conditions of high lipid availability. As both ketogenic diets and intermittent fasting increase circulating free fatty acid levels, AMPK activity, mitochondrial biogenesis, and mitophagy, these data suggest a potential unifying mechanism which may be important in mediating these effects.


Assuntos
Proteínas Quinases Ativadas por AMP , Ácidos Graxos , Camundongos , Animais , Fosforilação , Ácidos Graxos/metabolismo , Proteínas Quinases Ativadas por AMP/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Mitocôndrias/metabolismo , Homeostase , Autofagia , Triglicerídeos/metabolismo
2.
Int J Clin Pract ; 75(8): e13871, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33249713

RESUMO

AIMS: Opioid misuse and overuse have contributed to a widespread overdose crisis and many patients and physicians are considering medical cannabis to support opioid tapering and chronic pain control. Using a five-step modified Delphi process, we aimed to develop consensus-based recommendations on: 1) when and how to safely initiate and titrate cannabinoids in the presence of opioids, 2) when and how to safely taper opioids in the presence of cannabinoids and 3) how to monitor patients and evaluate outcomes when treating with opioids and cannabinoids. RESULTS: In patients with chronic pain taking opioids not reaching treatment goals, there was consensus that cannabinoids may be considered for patients experiencing or displaying opioid-related complications, despite psychological or physical interventions. There was consensus observed to initiate with a cannabidiol (CBD)-predominant oral extract in the daytime and consider adding tetrahydrocannabinol (THC). When adding THC, start with 0.5-3 mg, and increase by 1-2 mg once or twice weekly up to 30-40 mg/day. Initiate opioid tapering when the patient reports a minor/major improvement in function, seeks less as-needed medication to control pain and/or the cannabis dose has been optimised. The opioid tapering schedule may be 5%-10% of the morphine equivalent dose (MED) every 1 to 4 weeks. Clinical success could be defined by an improvement in function/quality of life, a ≥30% reduction in pain intensity, a ≥25% reduction in opioid dose, a reduction in opioid dose to <90 mg MED and/or reduction in opioid-related adverse events. CONCLUSIONS: This five-stage modified Delphi process led to the development of consensus-based recommendations surrounding the safe introduction and titration of cannabinoids in concert with tapering opioids.


Assuntos
Canabinoides , Dor Crônica , Analgésicos Opioides , Dor Crônica/tratamento farmacológico , Consenso , Humanos , Qualidade de Vida
3.
Can J Anaesth ; 68(7): 972-979, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33580878

RESUMO

PURPOSE: Perioperative hyperglycemia is common and is associated with significant morbidity. Although patient characteristics and surgery influence perioperative glucose metabolism, anesthetics have a significant impact. We hypothesized that mice that were obese and insulin-resistant would experience greater hyperglycemia in response to sevoflurane anesthesia compared with lean controls. We further hypothesized that sevoflurane-induced hyperglycemia would be attenuated by salsalate pre-treatment. METHODS: Lean and obese male C57BL/6J mice were anesthetized with sevoflurane for 60 min with or without pre-treatment of 62.5 mg·kg-1 salsalate. Blood glucose, plasma insulin, and glucose uptake into different tissues were measured. RESULTS: Under sevoflurane anesthesia, obese mice had higher blood glucose compared to lean mice. Increases in blood glucose were attenuated with acute salsalate pre-treatment at 60 min under anesthesia in obese mice (mean ± standard error of the mean [SEM], delta blood glucose; vehicle 5.79 ± 1.09 vs salsalate 1.91 ± 1.32 mM; P = 0.04) but did not reach statistical significance in lean mice (delta blood glucose, vehicle 4.39 ± 0.55 vs salsalate 2.79 ± 0.71 mM; P = 0.10). This effect was independent of changes in insulin but associated with an approx. 1.7-fold increase in glucose uptake into brown adipose tissue (vehicle 45.28 ± 4.57 vs salsalate 76.89 ± 12.23 µmol·g-1 tissue·hr-1; P < 0.001). CONCLUSION: These data show that salsalate can reduce sevoflurane-induced hyperglycemia in mice. This indicates that salsalate may represent a new class of therapeutics that, in addition to its anti-inflammatory and analgesic properties, may be useful to reduce perioperative hyperglycemia.


RéSUMé: OBJECTIF: L'hyperglycémie périopératoire est fréquente et est associée à une morbidité significative. Bien que les caractéristiques propres au patient et à la chirurgie influencent le métabolisme périopératoire du glucose, les anesthésiques ont un impact significatif. Nous avons émis l'hypothèse que l'hyperglycémie en réponse à une anesthésie à base de sévoflurane serait plus prononcée chez des souris obèses et insulino-résistantes que chez des souris témoins maigres. Nous avons en outre émis l'hypothèse que l'hyperglycémie induite par le sévoflurane serait atténuée par un prétraitement au salsalate. MéTHODE: Des souris mâles C57BL/6J maigres et obèses ont été anesthésiées avec du sévoflurane pendant 60 min avec ou sans prétraitement de 62,5 mg·kg−1 de salsalate. La glycémie, l'insuline plasmatique et l'absorption glycémique ont été mesurées dans différents tissus. RéSULTATS: Sous une anesthésie au sévoflurane, les souris obèses ont affiché une glycémie plus élevée que les souris maigres. Des augmentations de glucose sanguin ont été atténuées lors d'un prétraitement aigu à base de salsalate à 60 min sous anesthésie chez les souris obèses (moyenne ± erreur-type sur la moyenne [ETM], delta glycémique; véhicule 5,79 ± 1,09 vs salsalate 1,91 ± 1,32 mM, P = 0,04), mais elles n'étaient pas statistiquement significative chez les souris maigres (delta glycémique, véhicule 4,39 ± 0,55 vs salsalate 2,79 ± 0,71 mM; P = 0,10). Cet effet était indépendant des changements de l'insuline mais associé à une augmentation d'environ 1,7 fois de l'absorption glycémique dans les tissus adipeux bruns (véhicule 45,28 ± 4,57 vs salsalate 76,89 ± 12,23 µmol·g−1 tissu·h−1; P < 0,001). CONCLUSION: Ces données montrent que le salsalate peut réduire l'hyperglycémie induite par le sévoflurane chez la souris. Ceci indique que le salsalate pourrait constituer une nouvelle classe d'agents thérapeutiques qui, en plus de leurs propriétés anti-inflammatoires et analgésiques, pourraient être utiles pour réduire l'hyperglycémie périopératoire.


Assuntos
Hiperglicemia , Insulina , Animais , Glicemia , Glucose , Hiperglicemia/induzido quimicamente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Obesidade/complicações , Salicilatos , Sevoflurano
4.
J Biol Chem ; 292(40): 16653-16664, 2017 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-28808062

RESUMO

TBC1 domain family member 1 (TBC1D1), a Rab GTPase-activating protein and paralogue of Akt substrate of 160 kDa (AS160), has been implicated in both insulin- and 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase-mediated glucose transporter type 4 (GLUT4) translocation. However, the role of TBC1D1 in contracting muscle remains ambiguous. We therefore explored the metabolic consequence of ablating TBC1D1 in both resting and contracting skeletal muscles, utilizing a rat TBC1D1 KO model. Although insulin administration rapidly increased (p < 0.05) plasma membrane GLUT4 content in both red and white gastrocnemius muscles, the TBC1D1 ablation did not alter this response nor did it affect whole-body insulin tolerance, suggesting that TBC1D1 is not required for insulin-induced GLUT4 trafficking events. Consistent with findings in other models of altered TBC1D1 protein levels, whole-animal and ex vivo skeletal muscle fat oxidation was increased in the TBC1D1 KO rats. Although there was no change in mitochondrial content in the KO rats, maximal ADP-stimulated respiration was higher in permeabilized muscle fibers, which may contribute to the increased reliance on fatty acids in resting KO animals. Despite this increase in mitochondrial oxidative capacity, run time to exhaustion at various intensities was impaired in the KO rats. Moreover, contraction-induced increases in sarcolemmal GLUT4 content and glucose uptake were lower in the white gastrocnemius of the KO animals. Altogether, our results highlight a critical role for TBC1D1 in exercise tolerance and contraction-mediated translocation of GLUT4 to the plasma membrane in skeletal muscle.


Assuntos
Tolerância ao Exercício/fisiologia , Transportador de Glucose Tipo 4/metabolismo , Contração Muscular/fisiologia , Músculo Esquelético/metabolismo , Proteínas/metabolismo , Sarcolema/metabolismo , Animais , Transportador de Glucose Tipo 4/genética , Insulina/genética , Insulina/metabolismo , Oxirredução , Consumo de Oxigênio/fisiologia , Transporte Proteico/fisiologia , Proteínas/genética , Ratos , Ratos Sprague-Dawley , Ratos Transgênicos , Sarcolema/genética
5.
Curr Opin Clin Nutr Metab Care ; 20(4): 248-253, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28375880

RESUMO

PURPOSE OF REVIEW: Insulin resistance is an important risk factor for metabolic diseases such as type 2 diabetes, cardiovascular disease and certain cancers. A common characteristic of strategies that improve insulin sensitivity involves the activation of the energy sensing enzyme of the cell, AMP-activated protein kinase (AMPK). The purpose of this review is to explore the mechanisms associated with AMPK activation to improve insulin sensitivity with a focus on fatty acid metabolism. We will also discuss the literature surrounding direct AMPK activators to improve insulin resistance and important considerations for the design of direct AMPK activators. RECENT FINDINGS: AMPK activation can decrease de novo lipogenesis, increase fatty acid oxidation and promote mitochondrial integrity to improve insulin sensitivity. Drugs targeted to directly activate AMPK show therapeutic promise, yet in vivo data is lacking. SUMMARY: Designing a drug to directly activate AMPK may improve insulin resistance by reducing liver de novo lipogenesis and increasing brown and white adipose tissue mitochondrial function. However, in vivo experimental procedures to support this notion are not extensive and more research is required.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Ácidos Graxos/metabolismo , Resistência à Insulina/fisiologia , Tecido Adiposo/ultraestrutura , Animais , Ativação Enzimática/efeitos dos fármacos , Humanos , Lipogênese , Fígado/metabolismo , Mitocôndrias/fisiologia
6.
Am J Physiol Endocrinol Metab ; 311(4): E730-E740, 2016 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-27577854

RESUMO

Nonalcoholic fatty liver disease (NAFLD) is a growing worldwide epidemic and an important risk factor for the development of insulin resistance, type 2 diabetes, nonalcoholic steatohepatitis (NASH), and hepatic cellular carcinoma (HCC). Despite the prevalence of NAFLD, lifestyle interventions involving exercise and weight loss are the only accepted treatments for this disease. Over the last decade, numerous experimental compounds have been shown to improve NAFLD in preclinical animal models, and many of these therapeutics have been shown to increase the activity of the cellular energy sensor AMP-activated protein kinase (AMPK). Because AMPK activity is reduced by inflammation, obesity, and diabetes, increasing AMPK activity has been viewed as a viable therapeutic strategy to improve NAFLD. In this review, we propose three primary mechanisms by which AMPK activation may improve NAFLD. In addition, we examine the mechanisms by which AMPK is activated. Finally, we identify 27 studies that have used AMPK activators to reduce NAFLD. Future considerations for studies examining the relationship between AMPK and NAFLD are highlighted.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Ativadores de Enzimas/uso terapêutico , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/enzimologia , Animais , Humanos
7.
Biochem J ; 468(1): 125-32, 2015 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-25742316

RESUMO

Metformin is the mainstay therapy for type 2 diabetes (T2D) and many patients also take salicylate-based drugs [i.e., aspirin (ASA)] for cardioprotection. Metformin and salicylate both increase AMP-activated protein kinase (AMPK) activity but by distinct mechanisms, with metformin altering cellular adenylate charge (increasing AMP) and salicylate interacting directly at the AMPK ß1 drug-binding site. AMPK activation by both drugs results in phosphorylation of ACC (acetyl-CoA carboxylase; P-ACC) and inhibition of acetyl-CoA carboxylase (ACC), the rate limiting enzyme controlling fatty acid synthesis (lipogenesis). We find doses of metformin and salicylate used clinically synergistically activate AMPK in vitro and in vivo, resulting in reduced liver lipogenesis, lower liver lipid levels and improved insulin sensitivity in mice. Synergism occurs in cell-free assays and is specific for the AMPK ß1 subunit. These effects are also observed in primary human hepatocytes and patients with dysglycaemia exhibit additional improvements in a marker of insulin resistance (proinsulin) when treated with ASA and metformin compared with either drug alone. These data indicate that metformin-salicylate combination therapy may be efficacious for the treatment of non-alcoholic fatty liver disease (NAFLD) and T2D.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Aspirina/administração & dosagem , Fígado/efeitos dos fármacos , Fígado/metabolismo , Metformina/administração & dosagem , Animais , Cardiotônicos/administração & dosagem , Células Cultivadas , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Dieta Hiperlipídica/efeitos adversos , Sinergismo Farmacológico , Ativação Enzimática/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Hipoglicemiantes/administração & dosagem , Resistência à Insulina , Lipogênese/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL
8.
Diabetologia ; 57(8): 1693-702, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24913514

RESUMO

AIMS/HYPOTHESIS: Obesity is characterised by lipid accumulation in skeletal muscle, which increases the risk of developing insulin resistance and type 2 diabetes. AMP-activated protein kinase (AMPK) is a sensor of cellular energy status and is activated in skeletal muscle by exercise, hormones (leptin, adiponectin, IL-6) and pharmacological agents (5-amino-4-imidazolecarboxamide ribonucleoside [AICAR] and metformin). Phosphorylation of acetyl-CoA carboxylase 2 (ACC2) at S221 (S212 in mice) by AMPK reduces ACC activity and malonyl-CoA content but the importance of the AMPK-ACC2-malonyl-CoA pathway in controlling fatty acid metabolism and insulin sensitivity is not understood; therefore, we characterised Acc2 S212A knock-in (ACC2 KI) mice. METHODS: Whole-body and skeletal muscle fatty acid oxidation and insulin sensitivity were assessed in ACC2 KI mice and wild-type littermates. RESULTS: ACC2 KI mice were resistant to increases in skeletal muscle fatty acid oxidation elicited by AICAR. These mice had normal adiposity and liver lipids but elevated contents of triacylglycerol and ceramide in skeletal muscle, which were associated with hyperinsulinaemia, glucose intolerance and skeletal muscle insulin resistance. CONCLUSIONS/INTERPRETATION: These findings indicate that the phosphorylation of ACC2 S212 is required for the maintenance of skeletal muscle lipid and glucose homeostasis.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Acetil-CoA Carboxilase/metabolismo , Resistência à Insulina/fisiologia , Insulina/farmacologia , Músculo Esquelético/metabolismo , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacologia , Animais , Hipoglicemiantes/farmacologia , Leptina/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolismo dos Lipídeos/fisiologia , Malonil Coenzima A/metabolismo , Camundongos , Músculo Esquelético/efeitos dos fármacos , Obesidade/metabolismo , Oxirredução , Fosforilação/efeitos dos fármacos , Ribonucleotídeos/farmacologia
9.
J Physiol ; 591(6): 1551-61, 2013 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-23297307

RESUMO

In skeletal muscle, mitochondria exist as two subcellular populations known as subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria. SS mitochondria preferentially respond to exercise training, suggesting divergent transcriptional control of the mitochondrial genomes. The transcriptional co-activator peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) and mitochondrial transcription factor A (Tfam) have been implicated in the direct regulation of the mitochondrial genome in mice, although SS and IMF differences may exist, and the potential signalling events regulating the mitochondrial content of these proteins have not been elucidated. Therefore, we examined the potential for PGC-1α and Tfam to translocate to SS and IMF mitochondria in human subjects, and performed experiments in rodents to identify signalling mechanisms regulating these translocation events. Acute exercise in humans and rats increased PGC-1α content in SS but not IMF mitochondria. Acute exposure to 5-aminoimidazole-4-carboxamide-1-ß-ribofuranoside in rats recapitulated the exercise effect of increased PGC-1α protein within SS mitochondria only, suggesting that AMP-activated protein kinase (AMPK) signalling is involved. In addition, rendering AMPK inactive (AMPK kinase dead mice) prevented exercise-induced PGC-1α translocation to SS mitochondria, further suggesting that AMPK plays an integral role in these translocation events. In contrast to the conserved PGC-1α translocation to SS mitochondria across species (humans, rats and mice), acute exercise only increased mitochondrial Tfam in rats. Nevertheless, in rat resting muscle PGC-1α and Tfam co-immunoprecipate with α-tubulin, suggesting a common cytosolic localization. These data suggest that exercise causes translocation of PGC-1α preferentially to SS mitochondria in an AMPK-dependent manner.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Exercício Físico , Proteínas de Choque Térmico/metabolismo , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Proteínas de Ligação a RNA/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Quinases Ativadas por AMP/genética , Animais , Citosol/metabolismo , Humanos , Masculino , Camundongos , Camundongos Knockout , Mitocôndrias Musculares/classificação , Músculo Esquelético/fisiologia , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Esforço Físico , Transporte Proteico , Ratos , Ratos Sprague-Dawley , Sarcolema/metabolismo , Transdução de Sinais , Especificidade da Espécie , Transativadores/metabolismo , Adulto Jovem
10.
J Physiol ; 591(23): 6089-101, 2013 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-24081154

RESUMO

Mitochondrial dysfunction and reactive oxygen species (ROS) have been implicated in the aetiology of skeletal muscle insulin resistance, although there is considerable controversy regarding these concepts. Mitochondrial function has been traditionally assessed in the presence of saturating ADP, but ATP turnover and the resultant ADP is thought to limit respiration in vivo. Therefore, we investigated the potential link between submaximal ADP-stimulated respiration rates, ROS generation and skeletal muscle insulin sensitivity in a model of type 2 diabetes mellitus, the ZDF rat. Utilizing permeabilized muscle fibres we observed that submaximal ADP-stimulated respiration rates (250-2000 µm ADP) were lower in ZDF rats than in lean controls, which coincided with decreased adenine nucleotide translocase 2 (ANT2) protein content. This decrease in submaximal ADP-stimulated respiration occurred in the absence of a decrease in electron transport chain function. Treating ZDF rats with resveratrol improved skeletal muscle insulin resistance and this was associated with elevated submaximal ADP-stimulated respiration rates as well as an increase in ANT2 protein content. These results coincided with a greater ability of ADP to attenuate mitochondrial ROS emission and an improvement in cellular redox balance. Together, these data suggest that mitochondrial dysfunction is present in skeletal muscle insulin resistance when assessed at submaximal ADP concentrations and that ADP dynamics may influence skeletal muscle insulin sensitivity through alterations in the propensity for mitochondrial ROS emission.


Assuntos
Difosfato de Adenosina/fisiologia , Diabetes Mellitus Tipo 2/metabolismo , Resistência à Insulina/fisiologia , Músculo Esquelético/fisiologia , Translocador 2 do Nucleotídeo Adenina/metabolismo , Animais , Respiração Celular/efeitos dos fármacos , Respiração Celular/fisiologia , Glutationa/metabolismo , Dissulfeto de Glutationa/metabolismo , Peróxido de Hidrogênio/metabolismo , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Músculo Esquelético/efeitos dos fármacos , Ratos , Ratos Zucker , Resveratrol , Estilbenos/farmacologia
11.
J Biol Chem ; 287(28): 23502-16, 2012 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-22584574

RESUMO

For ~40 years it has been widely accepted that (i) the exercise-induced increase in muscle fatty acid oxidation (FAO) is dependent on the increased delivery of circulating fatty acids, and (ii) exercise training-induced FAO up-regulation is largely attributable to muscle mitochondrial biogenesis. These long standing concepts were developed prior to the recent recognition that fatty acid entry into muscle occurs via a regulatable sarcolemmal CD36-mediated mechanism. We examined the role of CD36 in muscle fuel selection under basal conditions, during a metabolic challenge (exercise), and after exercise training. We also investigated whether CD36 overexpression, independent of mitochondrial changes, mimicked exercise training-induced FAO up-regulation. Under basal conditions CD36-KO versus WT mice displayed reduced fatty acid transport (-21%) and oxidation (-25%), intramuscular lipids (less than or equal to -31%), and hepatic glycogen (-20%); but muscle glycogen, VO(2max), and mitochondrial content and enzymes did not differ. In acutely exercised (78% VO(2max)) CD36-KO mice, fatty acid transport (-41%), oxidation (-37%), and exercise duration (-44%) were reduced, whereas muscle and hepatic glycogen depletions were accelerated by 27-55%, revealing 2-fold greater carbohydrate use. Exercise training increased mtDNA and ß-hydroxyacyl-CoA dehydrogenase similarly in WT and CD36-KO muscles, but FAO was increased only in WT muscle (+90%). Comparable CD36 increases, induced by exercise training (+44%) or by CD36 overexpression (+41%), increased FAO similarly (84-90%), either when mitochondrial biogenesis and FAO enzymes were up-regulated (exercise training) or when these were unaltered (CD36 overexpression). Thus, sarcolemmal CD36 has a key role in muscle fuel selection, exercise performance, and training-induced muscle FAO adaptation, challenging long held views of mechanisms involved in acute and adaptive regulation of muscle FAO.


Assuntos
Adaptação Fisiológica/fisiologia , Antígenos CD36/metabolismo , Ácidos Graxos/metabolismo , Músculo Esquelético/metabolismo , Condicionamento Físico Animal/fisiologia , Adaptação Fisiológica/genética , Animais , Transporte Biológico , Western Blotting , Antígenos CD36/deficiência , Antígenos CD36/genética , Glucose/metabolismo , Glicogênio Hepático/metabolismo , Camundongos , Camundongos Knockout , Mitocôndrias Musculares/metabolismo , Oxirredução , Consumo de Oxigênio , Sarcolema/metabolismo , Triglicerídeos/metabolismo
12.
Biochem J ; 448(1): 13-20, 2012 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-22928974

RESUMO

Published values regarding the sensitivity (IC(50)) of CPT-I (carnitine palmitoyltransferase I) to M-CoA (malonyl-CoA) inhibition in isolated mitochondria are inconsistent with predicted in vivo rates of fatty acid oxidation. Therefore we have re-examined M-CoA inhibition kinetics under various P-CoA (palmitoyl-CoA) concentrations in both isolated mitochondria and PMFs (permeabilized muscle fibres). PMFs have an 18-fold higher IC(50) (0.61 compared with 0.034 µM) in the presence of 25 µM P-CoA and a 13-fold higher IC(50) (6.3 compared with 0.49 µM) in the presence of 150 µM P-CoA compared with isolated mitochondria. M-CoA inhibition kinetics determined in PMFs predicts that CPT-I activity is inhibited by 33% in resting muscle compared with >95% in isolated mitochondria. Additionally, the ability of M-CoA to inhibit CPT-I appears to be dependent on P-CoA concentration, as the relative inhibitory capacity of M-CoA is decreased with increasing P-CoA concentrations. Altogether, the use of PMFs appears to provide an M-CoA IC(50) that better reflects the predicted in vivo rates of fatty acid oxidation. These findings also demonstrate that the ratio of [P-CoA]/[M-CoA] is critical for regulating CPT-I activity and may partially rectify the in vivo disconnect between M-CoA content and CPT-I flux within the context of exercise and Type 2 diabetes.


Assuntos
Carnitina O-Palmitoiltransferase/metabolismo , Ácidos Graxos/metabolismo , Malonil Coenzima A/farmacologia , Mitocôndrias Musculares/enzimologia , Animais , Carnitina/metabolismo , Carnitina O-Palmitoiltransferase/antagonistas & inibidores , Permeabilidade da Membrana Celular , Relação Dose-Resposta a Droga , Concentração Inibidora 50 , Cinética , Malonil Coenzima A/metabolismo , Mitocôndrias Musculares/metabolismo , Fibras Musculares de Contração Lenta/enzimologia , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/enzimologia , Oxirredução , Consumo de Oxigênio , Palmitoil Coenzima A/metabolismo , Condicionamento Físico Animal , Ratos , Ratos Sprague-Dawley
13.
Exerc Sport Sci Rev ; 40(4): 211-7, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22653277

RESUMO

Carnitine palmitoyltransferase I has been viewed historically as the sole regulator of fatty acid oxidation. However, we have identified fatty acid translocase/CD36 as an additional control point. Specifically, fatty acid translocase/CD36 seems to have a novel dual mechanism of action with regard to fatty acid oxidation during exercise, influencing transport of lipids across the sarcolemmal membrane and into the mitochondria.


Assuntos
Antígenos CD36/metabolismo , Exercício Físico/fisiologia , Metabolismo dos Lipídeos , Membranas Mitocondriais/metabolismo , Músculo Esquelético/metabolismo , Sarcolema/metabolismo , Animais , Humanos , Oxirredução , Regulação para Cima
14.
Biochem J ; 437(1): 125-34, 2011 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-21463259

RESUMO

FAT/CD36 (fatty acid translocase/Cluster of Differentiation 36), a plasma membrane fatty-acid transport protein, has been found on mitochondrial membranes; however, it remains unclear where FAT/CD36 resides on this organelle or its functional role within mitochondria. In the present study, we demonstrate, using several different approaches, that in skeletal muscle FAT/CD36 resides on the OMM (outer mitochondrial membrane). To determine the functional role of mitochondrial FAT/CD36 in this tissue, we determined oxygen consumption rates in permeabilized muscle fibres in WT (wild-type) and FAT/CD36-KO (knockout) mice using a variety of substrates. Despite comparable muscle mitochondrial content, as assessed by unaltered mtDNA (mitochondrial DNA), citrate synthase, ß-hydroxyacyl-CoA dehydrogenase, cytochrome c oxidase complex IV and respiratory capacities [maximal OXPHOS (oxidative phosphorylation) respiration] in WT and KO mice, palmitate-supported respiration was 34% lower in KO animals. In contrast, palmitoyl-CoA-supported respiration was unchanged. These results indicate that FAT/CD36 is key for palmitate-supported respiration. Therefore we propose a working model of mitochondrial fatty-acid transport, in which FAT/CD36 is positioned on the OMM, upstream of long-chain acyl-CoA synthetase, thereby contributing to the regulation of mitochondrial fatty-acid transport. We further support this model by providing evidence that FAT/CD36 is not located in mitochondrial contact sites, and therefore does not directly interact with carnitine palmitoyltransferase-I as original proposed.


Assuntos
Antígenos CD36/análise , Membranas Mitocondriais/metabolismo , Palmitatos/metabolismo , Acil Coenzima A/metabolismo , Animais , Antígenos CD36/genética , Antígenos CD36/metabolismo , Coenzima A Ligases/metabolismo , Camundongos , Camundongos Knockout , Microscopia Eletrônica de Transmissão , Músculo Esquelético/metabolismo , Oxirredução , Ratos
15.
Cell Metab ; 34(6): 919-936.e8, 2022 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-35675800

RESUMO

Elevated liver de novo lipogenesis contributes to non-alcoholic steatohepatitis (NASH) and can be inhibited by targeting acetyl-CoA carboxylase (ACC). However, hypertriglyceridemia limits the use of pharmacological ACC inhibitors as a monotherapy. ATP-citrate lyase (ACLY) generates acetyl-CoA and oxaloacetate from citrate, but whether inhibition is effective for treating NASH is unknown. Here, we characterize a new mouse model that replicates many of the pathological and molecular drivers of NASH and find that genetically inhibiting ACLY in hepatocytes reduces liver malonyl-CoA, oxaloacetate, steatosis, and ballooning as well as blood glucose, triglycerides, and cholesterol. Pharmacological inhibition of ACLY mirrors genetic inhibition but has additional positive effects on hepatic stellate cells, liver inflammation, and fibrosis. Mendelian randomization of human variants that mimic reductions in ACLY also associate with lower circulating triglycerides and biomarkers of NASH. These data indicate that inhibiting liver ACLY may be an effective approach for treatment of NASH and dyslipidemia.


Assuntos
ATP Citrato (pro-S)-Liase , Dislipidemias , Hepatopatia Gordurosa não Alcoólica , ATP Citrato (pro-S)-Liase/antagonistas & inibidores , Acetil-CoA Carboxilase , Animais , Dislipidemias/tratamento farmacológico , Dislipidemias/patologia , Fígado , Cirrose Hepática/tratamento farmacológico , Cirrose Hepática/patologia , Camundongos , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/patologia , Oxaloacetatos/metabolismo , Triglicerídeos
16.
Pharm Pract (Granada) ; 19(3): 2377, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34621449

RESUMO

BACKGROUND: Recent approvals for novel agents such as the small molecule Janus kinase inhibitors (JAKi), combined with the advent of biosimilars has widened the gamut of available therapeutic options in the treatment of rheumatoid arthritis (RA). This combined with the introduction of mandatory non- medical switches to biosimilars in some jurisdictions by both public and private payors has led to a significant increase in the volume of therapeutic changes for patients. Pharmacists are well positioned to ensure effective and safe transitions, however there is a significant unmet need for objective and subjective clinical guidance around therapy as well disease state monitoring in RA that facilitates best practices throughout the patient journey. OBJECTIVE: In this paper we aim to create a consensus derived monitoring algorithm for pharmacists to facilitate best practices throughout therapeutic transitions from originator biologic to other originator biologics, biosimilars, and Janus kinase inhibitors in RA. METHODS: The Nominal Group Technique (NGT) was used to understand if consensus could be found among the participants. Clinically relevant questions were developed to capture solutions to the identified unmet need. The faculty considered the questions as individuals, and privately generated answers/ideas. After discussion and consideration, the participants ranked the ideas and established a consensus. RESULTS: Based on the outcome of the consensus discussions, an algorithm was created to help guide pharmacists through therapeutic transitions in RA. The tool covers important topics such as pre-transition considerations, avoiding the nocebo effect for biosimilars, specific considerations for each drug or class, monitoring efficacy, and when to refer. CONCLUSIONS: New classes of anti-rheumatic drugs including JAKi, along with the introduction of biosimilars are presenting more opportunity for therapeutic changes and monitoring in patients with RA. We hope our evidence-based consensus derived guidance tool will assist frontline pharmacists in supporting their patients to a successful therapeutic transition in RA.

17.
Mol Metab ; 53: 101321, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34425254

RESUMO

OBJECTIVE: Salsalate is a prodrug of salicylate that lowers blood glucose in people with type 2 diabetes. AMP-activated protein kinase (AMPK) is an αßγ heterotrimer which inhibits macrophage inflammation and the synthesis of fatty acids and cholesterol in the liver through phosphorylation of acetyl-CoA carboxylase (ACC) and HMG-CoA reductase (HMGCR), respectively. Salicylate binds to and activates AMPKß1-containing heterotrimers that are highly expressed in both macrophages and liver, but the potential importance of AMPK and ability of salsalate to reduce atherosclerosis have not been evaluated. METHODS: ApoE-/- and LDLr-/- mice with or without (-/-) germline or bone marrow AMPKß1, respectively, were treated with salsalate, and atherosclerotic plaque size was evaluated in serial sections of the aortic root. Studies examining the effects of salicylate on markers of inflammation, fatty acid and cholesterol synthesis and proliferation were conducted in bone marrow-derived macrophages (BMDMs) from wild-type mice or mice lacking AMPKß1 or the key AMPK-inhibitory phosphorylation sites on ACC (ACC knock-in (KI)-ACC KI) or HMGCR (HMGCR-KI). RESULTS: Salsalate reduced atherosclerotic plaques in the aortic roots of ApoE-/- mice, but not ApoE-/- AMPKß1-/- mice. Similarly, salsalate reduced atherosclerosis in LDLr-/- mice receiving wild-type but not AMPKß1-/- bone marrow. Reductions in atherosclerosis by salsalate were associated with reduced macrophage proliferation, reduced plaque lipid content and reduced serum cholesterol. In BMDMs, this suppression of proliferation by salicylate required phosphorylation of HMGCR and the suppression of cholesterol synthesis. CONCLUSIONS: These data indicate that salsalate suppresses macrophage proliferation and atherosclerosis through an AMPKß1-dependent pathway, which may involve HMGCR phosphorylation and cholesterol synthesis. Since rapidly-proliferating macrophages are a hallmark of atherosclerosis, these data indicate further evaluation of salsalate as a potential therapeutic agent for treating atherosclerotic cardiovascular disease.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Aterosclerose/metabolismo , Salicilatos/metabolismo , Proteínas Quinases Ativadas por AMP/deficiência , Animais , Células Cultivadas , Camundongos , Camundongos Knockout
18.
J Cannabis Res ; 3(1): 22, 2021 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-34215346

RESUMO

BACKGROUND: Globally, medical cannabis legalization has increased in recent years and medical cannabis is commonly used to treat chronic pain. However, there are few randomized control trials studying medical cannabis indicating expert guidance on how to dose and administer medical cannabis safely and effectively is needed. METHODS: Using a multistage modified Delphi process, twenty global experts across nine countries developed consensus-based recommendations on how to dose and administer medical cannabis in patients with chronic pain. RESULTS: There was consensus that medical cannabis may be considered for patients experiencing neuropathic, inflammatory, nociplastic, and mixed pain. Three treatment protocols were developed. A routine protocol where the clinician initiates the patient on a CBD-predominant variety at a dose of 5 mg CBD twice daily and titrates the CBD-predominant dose by 10 mg every 2 to 3 days until the patient reaches their goals, or up to 40 mg/day. At a CBD-predominant dose of 40 mg/day, clinicians may consider adding THC at 2.5 mg and titrate by 2.5 mg every 2 to 7 days until a maximum daily dose of 40 mg/day of THC. A conservative protocol where the clinician initiates the patient on a CBD-predominant variety at a dose of 5 mg once daily and titrates the CBD-predominant dose by 10 mg every 2 to 3 days until the patient reaches their goals, or up to 40 mg/day. At a CBD-predominant dose of 40 mg/day, clinicians may consider adding THC at 1 mg/day and titrate by 1 mg every 7 days until a maximum daily dose of 40 mg/day of THC. A rapid protocol where the clinician initiates the patient on a balanced THC:CBD variety at 2.5-5 mg of each cannabinoid once or twice daily and titrates by 2.5-5 mg of each cannabinoid every 2 to 3 days until the patient reaches his/her goals or to a maximum THC dose of 40 mg/day. CONCLUSIONS: In summary, using a modified Delphi process, expert consensus-based recommendations were developed on how to dose and administer medical cannabis for the treatment of patients with chronic pain.

19.
Nat Commun ; 12(1): 5163, 2021 08 27.
Artigo em Inglês | MEDLINE | ID: mdl-34453052

RESUMO

Obesity results from a caloric imbalance between energy intake, absorption and expenditure. In both rodents and humans, diet-induced thermogenesis contributes to energy expenditure and involves the activation of brown adipose tissue (BAT). We hypothesize that environmental toxicants commonly used as food additives or pesticides might reduce BAT thermogenesis through suppression of uncoupling protein 1 (UCP1) and this may contribute to the development of obesity. Using a step-wise screening approach, we discover that the organophosphate insecticide chlorpyrifos suppresses UCP1 and mitochondrial respiration in BAT at concentrations as low as 1 pM. In mice housed at thermoneutrality and fed a high-fat diet, chlorpyrifos impairs BAT mitochondrial function and diet-induced thermogenesis, promoting greater obesity, non-alcoholic fatty liver disease (NAFLD) and insulin resistance. This is associated with reductions in cAMP; activation of p38MAPK and AMPK; protein kinases critical for maintaining UCP1 and mitophagy, respectively in BAT. These data indicate that the commonly used pesticide chlorpyrifos, suppresses diet-induced thermogenesis and the activation of BAT, suggesting its use may contribute to the obesity epidemic.


Assuntos
Tecido Adiposo Marrom/fisiopatologia , Clorpirifos/metabolismo , Obesidade/fisiopatologia , Praguicidas/metabolismo , Termogênese/efeitos dos fármacos , Quinases Proteína-Quinases Ativadas por AMP , Animais , Clorpirifos/toxicidade , AMP Cíclico/metabolismo , Metabolismo Energético , Contaminação de Alimentos/análise , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/induzido quimicamente , Obesidade/metabolismo , Praguicidas/toxicidade , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/genética , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
20.
Diabetes Ther ; 11(11): 2595-2609, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32893337

RESUMO

INTRODUCTION: Proper insulin injection technique has demonstrated positive clinical outcomes in patients with diabetes. A Canadian-based practice reflective was undertaken to evaluate the current state of understanding of injection technique practices by patients administering insulin, and the importance physicians place on proper injection technique. METHODS: Twenty-four sites across Canada completed a practice profile survey and enrolled adult non-pregnant patients with either type 1 or type 2 diabetes injecting insulin using an insulin pen. Seven areas of proper injection technique to be evaluated were identified by the study steering committee: size of injection site, use of a skin lift, needle reuse, length of the needle, duration of the needle in the skin, injection into lipohypertrophic tissue, and applied injection force. During a scheduled visit, each patient filled out the Injection Technique Survey and the physician documented the answers via an electronic database. RESULTS: Almost all physicians surveyed agreed (96%) that proper insulin injection technique is important or very important and 80% indicated they were either completely confident or fairly confident in discussing overall insulin injection technique. All patients surveyed were making at least one insulin injection technique error within the following categories: applied injection force (76%), area size of injection site (64%), duration of pen needle in skin (61%), pen needle reuse (39%), performs a skin lift with a 4 or 5 mm needle (38%), uses a longer pen needle than required (34%), and injection of insulin into lipohypertrophic tissue (37%). CONCLUSION: Patients commonly make insulin injection errors. Patient and physician education on optimal insulin injection technique continues to be an unmet medical need for the treatment of patients with diabetes. Prospective trials examining the impact of new technology, diabetes educational teams, and e-learning as educational interventions are potential avenues to explore in future studies to support improved insulin injection technique.

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