RESUMEN
Oxidative stress is associated with obesity. However, glutathione (GSH), one of the body's most abundant antioxidants, plays dual and seemingly contradictory roles in the development of obesity and its comorbidities. Glutathione has complex metabolic and biochemical fates and is a cofactor for several enzymes that function in modifying obesity-related responses. For example, depletion of GSH increases energy metabolism and reduces adipose accretion, while elevation of GSH peroxidase activity induces insulin resistance. This review summarizes the literature linking GSH and its related enzymes, GSH peroxidase, glutaredoxins, and glutathione S-transferases, to obesity and its pertinent endpoints (e.g., energy metabolism, inflammation, and insulin resistance).
Asunto(s)
Glutatión/metabolismo , Obesidad , Antioxidantes , Humanos , Resistencia a la Insulina/fisiología , Obesidad/metabolismo , Obesidad/fisiopatología , Estrés Oxidativo , Oxidorreductasas/metabolismoRESUMEN
BACKGROUND: Hibernating myocardium is characterized by viable yet dysfunctional myocardium secondary to chronic ischemia, with studies demonstrating incomplete early recovery after coronary artery bypass graft (CABG). We tested whether mitochondrial fusion proteins, an indicator of mitochondrial biogenesis, are increased in hibernating myocardium post-CABG. METHODS: A constrictor was placed on the left anterior descending (LAD) artery of nine pigs. Four of these pigs additionally underwent CABG 12 wk later with a left internal mammary artery graft to the LAD distal to the constrictor. Five pigs had a constrictor placed but did not undergo CABG (Hib). Five pigs did not have a constrictor placed (control). Computerized tomography angiography was used to confirm stenosis at the site of constrictor placement and patency of left internal mammary artery grafts. Regional blood flows were determined at baseline and during 40 µg/kg/min dobutamine infusion. Mitochondrial proteins were quantified by Western blot. RESULTS: Blood flow in the LAD region after CABG was lower than remote regions during dobutamine infusion (2.54 ± 0.24 versus 3.46 ± 0.33 mL/min/g; P < 0.05). Electron transport chain proteins were â¼70% lower in Hib compared with those in control and failed to normalize after CABG. Post-CABG, PGC1α nuclear-bound content was increased compared with Hib (9.02 ± 0.48 versus 5.54 ± 0.98 arbitrary units, respectively; P < 0.05), and expression of mitofusins-1 and 2 and optic atrophy-1 more than doubled. CONCLUSIONS: PGC1α and mitochondrial fusion proteins are increased 4 wk post-CABG in hibernating hearts, indicating mitochondrial fusion has begun to occur and signaling early mitochondrial recovery. Future studies should address changes in maximal myocardial oxygen consumption relative to mitochondrial protein expression.
Asunto(s)
Puente de Arteria Coronaria , Proteínas del Complejo de Cadena de Transporte de Electrón/metabolismo , Proteínas Mitocondriales/metabolismo , Recambio Mitocondrial , Aturdimiento Miocárdico/cirugía , Animales , Circulación Coronaria , Femenino , Revascularización Miocárdica , Aturdimiento Miocárdico/metabolismo , PorcinosRESUMEN
Inflammation plays a critical role in the pathology of obesity-linked insulin resistance and is mechanistically linked to the effects of macrophage-derived cytokines on adipocyte energy metabolism, particularly that of the mitochondrial branched-chain amino acid (BCAA) and tricarboxylic acid (TCA) pathways. To address the role of inflammation on energy metabolism in adipocytes, we used high fat-fed C57BL/6J mice and lean controls and measured the down-regulation of genes linked to BCAA and TCA cycle metabolism selectively in visceral but not in subcutaneous adipose tissue, brown fat, liver, or muscle. Using 3T3-L1 cells, TNFα, and other proinflammatory cytokine treatments reduced the expression of the genes linked to BCAA transport and oxidation. Consistent with this, [(14)C]-leucine uptake and conversion to triglycerides was markedly attenuated in TNFα-treated adipocytes, whereas the conversion to protein was relatively unaffected. Because inflammatory cytokines lead to the induction of endoplasmic reticulum stress, we evaluated the effects of tunicamycin or thapsigargin treatment of 3T3-L1 cells and measured a similar down-regulation in the BCAA/TCA cycle pathway. Moreover, transgenic mice overexpressing X-box binding protein 1 in adipocytes similarly down-regulated genes of BCAA and TCA metabolism in vivo. These results indicate that inflammation and endoplasmic reticulum stress attenuate lipogenesis in visceral adipose depots by down-regulating the BCAA/TCA metabolism pathway and are consistent with a model whereby the accumulation of serum BCAA in the obese insulin-resistant state is linked to adipose inflammation.
Asunto(s)
Adipocitos/metabolismo , Aminoácidos de Cadena Ramificada/metabolismo , Estrés del Retículo Endoplásmico , Inflamación/patología , Células 3T3-L1 , Adipocitos/efectos de los fármacos , Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/metabolismo , Aminoácidos de Cadena Ramificada/química , Animales , Transporte Biológico/efectos de los fármacos , Transporte Biológico/genética , Regulación hacia Abajo/efectos de los fármacos , Estrés del Retículo Endoplásmico/efectos de los fármacos , Estrés del Retículo Endoplásmico/genética , Inflamación/genética , Espacio Intracelular/efectos de los fármacos , Espacio Intracelular/metabolismo , Leucina/metabolismo , Masculino , Metabolómica , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Obesidad/genética , Obesidad/metabolismo , Obesidad/patología , Factor de Necrosis Tumoral alfa/farmacologíaRESUMEN
BACKGROUND: We have previously shown that mitochondrial uncoupling protein-2 (UCP-2) is increased in a swine model of hibernating myocardium (HM). Although UCP-2 reduces oxidant stress, it can promote inefficiency of the electron transport chain. In this study, we tested whether UCP-2 remains increased in revascularized HM (RHM) after coronary artery bypass grafting (CABG). METHODS: Seven swine underwent thoracotomy with placement of a constrictor on the left anterior descending artery (LAD). Twelve weeks later, a left internal mammary artery graft was placed on the distal LAD. Four weeks post-CABG, computed tomography angiography documented patent grafts and function. At the terminal study, blood flow to the LAD and remote territories were assessed during high dose dobutamine and mitochondria isolated from both regions for analysis. Comparisons were made to a group of swine with HM who underwent constrictor placement without bypass grafting (n = 4). RESULTS: During dobutamine infusion, RHM demonstrated lower blood flows (2.44 ± 0.23 versus 3.43 ± 0.30 mL/min/g; P < 0.05) and reduced wall thickening (33 ± 9% versus 52 ± 13%; P < 0.05) compared with remote regions. RHM had lower respiratory control indices (3.7 ± 0.3 versus 4.3 ± 0.4; P < 0.05) with persistently increased UCP-2 content. CONCLUSIONS: Despite patent grafts, RHM demonstrates a submaximal response to dobutamine infusion and increased mitochondrial UCP-2 expression. These data support the notion that recovery of the mitochondria in RHM is delayed early post-CABG and may contribute to impaired oxygen consumption and contractile reserve during catecholamine challenges.
Asunto(s)
Puente de Arteria Coronaria , Canales Iónicos/metabolismo , Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Aturdimiento Miocárdico/metabolismo , Aturdimiento Miocárdico/cirugía , Animales , Técnicas de Imagen Cardíaca , Cardiotónicos/farmacología , Respiración de la Célula , Enfermedad Crónica , Circulación Coronaria/efectos de los fármacos , Circulación Coronaria/fisiología , Modelos Animales de Enfermedad , Dobutamina/farmacología , Ecocardiografía Doppler , Insuficiencia Cardíaca/tratamiento farmacológico , Insuficiencia Cardíaca/metabolismo , Insuficiencia Cardíaca/cirugía , Mitocondrias/efectos de los fármacos , Aturdimiento Miocárdico/tratamiento farmacológico , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/fisiología , Porcinos , Tomografía Computarizada por Rayos X , Proteína Desacopladora 2RESUMEN
Myocardial responses to chronic ischemia represent a continuum of adaptations resulting, over time, in a stress-resistant phenotype. One such adaptation, hibernating myocardium (HM), has increased antioxidant capacity that protects against ischemia-induced oxidative stress. Studies have suggested that revascularization alone may not fully restore cardiac function, highlighting the need for targeted therapies to serve as adjuncts to the innate healing process following revascularization. In our review, we discuss current understanding of HM and the recovery process following surgical revascularization, focusing on animal models of HM to understand implications for human patients.
Asunto(s)
Revascularización Miocárdica , Aturdimiento Miocárdico/cirugía , Animales , Modelos Animales de Enfermedad , Metabolismo Energético , Humanos , Mitocondrias Cardíacas/metabolismo , Aturdimiento Miocárdico/etiología , Aturdimiento Miocárdico/fisiopatología , Aturdimiento Miocárdico/terapia , Estrés OxidativoRESUMEN
Obesity-induced insulin resistance has been linked to adipose tissue lipid aldehyde production and protein carbonylation. Trans-4-hydroxy-2-nonenal (4-HNE) is the most abundant lipid aldehyde in murine adipose tissue and is metabolized by glutathione S-transferase A4 (GSTA4), producing glutathionyl-HNE (GS-HNE) and its metabolite glutathionyl-1,4-dihydroxynonene (GS-DHN). The objective of this study was to evaluate adipocyte production of GS-HNE and GS-DHN and their effect on macrophage inflammation. Compared with lean controls, GS-HNE and GS-DHN were more abundant in visceral adipose tissue of ob/ob mice and diet-induced obese, insulin-resistant mice. High glucose and oxidative stress induced production of GS-HNE and GS-DHN by 3T3-L1 adipocytes in a GSTA4-dependent manner, and both glutathionylated metabolites induced secretion of tumor necrosis factor-α from RAW 264.7 and primary peritoneal macrophages. Targeted microarray analysis revealed GS-HNE and GS-DHN induced expression of inflammatory genes, including C3, C4b, c-Fos, igtb2, Nfkb1, and Nos2. Transgenic overexpression of GSTA4 in mouse adipose tissue led to increased production of GS-HNE associated with higher fasting glucose levels and moderately impaired glucose tolerance. These results indicated adipocyte oxidative stress results in GSTA4-dependent production of proinflammatory glutathione metabolites, GS-HNE and GS-DHN, which may represent a novel mechanism by which adipocyte dysfunction results in tissue inflammation and insulin resistance.
Asunto(s)
Adipocitos/metabolismo , Inflamación/metabolismo , Resistencia a la Insulina/fisiología , Macrófagos/metabolismo , Estrés Oxidativo/fisiología , Adipocitos/efectos de los fármacos , Aldehído Reductasa/metabolismo , Aldehídos/metabolismo , Animales , Glucosa/farmacología , Glutatión/metabolismo , Glutatión Transferasa/metabolismo , Macrófagos/efectos de los fármacos , Ratones , Estrés Oxidativo/efectos de los fármacos , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Obesity is an important risk factor for asthma but the mechanistic basis for this association is not well understood. In the current study, the impact of obesity on lung inflammatory responses after allergen exposure was investigated. C57BL/6 mice maintained on a high-fat diet (HFD) or a normal diet (ND) after weaning were sensitized and challenged with cockroach allergen (CRA). Airway inflammation was assessed based on inflammatory cell recruitment, measurement of lung Th1-Th2 cytokines, chemokines, eicosanoids, and other proinflammatory mediators as well as airway hyperresponsiveness (AHR). CRA-challenged mice fed a HFD exhibited significantly decreased allergen-induced airway eosinophilia along with reduced lung IL-5, IL-13, LTC4, CCL11, and CCL2 levels as well as reduced mucus secretion and smooth muscle mass compared to ND fed mice. However, allergen-challenged HFD fed mice demonstrated significantly increased PAI-1 and reduced PGE2 levels in the lung relative to corresponding ND fed mice. Interestingly, saline-exposed HFD fed mice demonstrated elevated baseline levels of TGF-ß1, arginase-1, hypoxia-inducible factor-1α, and lung collagen expression associated with decreased lung function compared to corresponding ND fed mice. These studies indicate that a HFD inhibits airway eosinophilia while altering levels of PAI-1 and PGE2 in response to CRA in mice. Further, a HFD can lead to the development of lung fibrosis even in the absence of allergen exposure which could be due to innate elevated levels of specific profibrotic factors, potentially affecting lung function during asthma.
Asunto(s)
Alérgenos/efectos adversos , Dieta Alta en Grasa/efectos adversos , Eosinofilia/prevención & control , Fibrosis Pulmonar/etiología , Enfermedades Respiratorias/prevención & control , Animales , Arginasa/metabolismo , Asma/etiología , Asma/inmunología , Hiperreactividad Bronquial/inmunología , Quimiocinas/metabolismo , Cucarachas/inmunología , Citocinas/metabolismo , Modelos Animales de Enfermedad , Eicosanoides/metabolismo , Eosinofilia/inmunología , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Pulmón/inmunología , Pulmón/patología , Pulmón/fisiopatología , Masculino , Ratones , Ratones Endogámicos C57BL , Obesidad/complicaciones , Obesidad/inmunología , Fibrosis Pulmonar/inmunología , Fibrosis Pulmonar/patología , Enfermedades Respiratorias/inmunología , Factores de Riesgo , Serpina E2/metabolismo , Factor de Crecimiento Transformador beta1/metabolismoRESUMEN
Obesity results in increased macrophage recruitment to adipose tissue that promotes a chronic low-grade inflammatory state linked to increased fatty acid efflux from adipocytes. Activated macrophages produce a variety of pro-inflammatory lipids such as leukotriene C4 (LTC4) and 5-, 12-, and 15-hydroxyeicosatetraenoic acid (HETE) suggesting the hypothesis that fatty acids may stimulate eicosanoid synthesis. To assess if eicosanoid production increases with obesity, adipose tissue of leptin deficient ob/ob mice was analyzed. In ob/ob mice, LTC4 and 12-HETE levels increased in the visceral (but not subcutaneous) adipose depot while the 5-HETE levels decreased and 15-HETE abundance was unchanged. Since macrophages produce the majority of inflammatory molecules in adipose tissue, treatment of RAW264.7 or primary peritoneal macrophages with free fatty acids led to increased secretion of LTC4 and 5-HETE, but not 12- or 15-HETE. Fatty acid binding proteins (FABPs) facilitate the intracellular trafficking of fatty acids and other hydrophobic ligands and in vitro stabilize the LTC4 precursor leukotriene A4 (LTA4) from non-enzymatic hydrolysis. Consistent with a role for FABPs in LTC4 synthesis, treatment of macrophages with HTS01037, a specific FABP inhibitor, resulted in a marked decrease in both basal and fatty acid-stimulated LTC4 secretion but no change in 5-HETE production or 5-lipoxygenase expression. These results indicate that the products of adipocyte lipolysis may stimulate the 5-lipoxygenase pathway leading to FABP-dependent production of LTC4 and contribute to the insulin resistant state.
Asunto(s)
Tejido Adiposo/inmunología , Proteínas de Unión a Ácidos Grasos/inmunología , Ácidos Grasos/inmunología , Leucotrieno C4/inmunología , Macrófagos/inmunología , Obesidad/inmunología , Ácido 12-Hidroxi-5,8,10,14-Eicosatetraenoico/análisis , Ácido 12-Hidroxi-5,8,10,14-Eicosatetraenoico/inmunología , Tejido Adiposo/patología , Animales , Línea Celular , Células Cultivadas , Ácidos Grasos/análisis , Femenino , Ácidos Hidroxieicosatetraenoicos/análisis , Ácidos Hidroxieicosatetraenoicos/inmunología , Macrófagos/patología , Ratones , Ratones Endogámicos C57BL , Ratones Obesos , Obesidad/patologíaRESUMEN
Protein carbonylation is the covalent modification of proteins by α,ß-unsaturated aldehydes produced by nonenzymatic lipid peroxidation of polyunsaturated fatty acids. The most widely studied aldehyde product of lipid peroxidation, trans-4-hydroxy-2-nonenal (4-HNE), is associated with obesity-induced metabolic dysfunction and has demonstrated reactivity toward key proteins involved in cellular function. However, 4-HNE is only one of many lipid peroxidation products and the lipid aldehyde profile in adipose tissue has not been characterized. To further understand the role of oxidative stress in obesity-induced metabolic dysfunction, a novel LC-MS/MS method was developed to evaluate aldehyde products of lipid peroxidation and applied to the analysis of adipose tissue. 4-HNE and trans-4-oxo-2-nonenal (4-ONE) were the most abundant aldehydes present in adipose tissue. In high fat-fed C57Bl/6J and ob/ob mice the levels of lipid peroxidation products were increased 5- to 11-fold in epididymal adipose, unchanged in brown adipose, but decreased in subcutaneous adipose tissue. Epididymal adipose tissue of high fat-fed mice also exhibited increased levels of proteins modified by 4-HNE and 4-ONE, whereas subcutaneous adipose tissue levels of these modifications were decreased. High fat feeding of C57Bl/6J mice resulted in decreased expression of a number of genes linked to antioxidant biology selectively in epididymal adipose tissue. Moreover, TNFα treatment of 3T3-L1 adipocytes resulted in decreased expression of GSTA4, GPx4, and Prdx3 while upregulating the expression of SOD2. These results suggest that inflammatory cytokines selectively downregulate antioxidant gene expression in visceral adipose tissue, resulting in elevated lipid aldehydes and increased protein carbonylation.
Asunto(s)
Tejido Adiposo/metabolismo , Aldehídos/metabolismo , Peroxidación de Lípido , Estrés Oxidativo , Células 3T3-L1 , Animales , Dieta Alta en Grasa , Ácidos Grasos Insaturados/metabolismo , Regulación de la Expresión Génica , Glutatión Peroxidasa/metabolismo , Glutatión Transferasa/metabolismo , Ratones , Obesidad , Peroxiredoxina III/metabolismo , Fosfolípido Hidroperóxido Glutatión Peroxidasa , Superóxido Dismutasa/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Although protection against necrosis has been observed in both hibernating (HIB) and ischemic preconditioned hearts in the second window of protection (SWOP), a comparison of the mitochondrial proteome between the two entities has not been previously performed. Anesthetized swine underwent instrumentation with a fixed constrictor around the LAD artery and were followed for 12 weeks (HIB; N=7). A second group of anesthetized swine underwent ischemic preconditioning by inflating a balloon within the LAD artery 10 times for 2 min, each separated by 2 min reperfusion and were sacrificed 24h later (SWOP; N=7). Myocardial blood flow and high-energy nucleotides were obtained in the LAD region and normalized to remote regions. Post-sacrifice, protein content as measured with iTRAQ was compared in isolated mitochondria from the LAD area of a Sham heart. Basal regional blood flow in the LAD region when normalized to the remote region was 0.86±0.04 in HIB and 1.02±0.02 in SWOP tissue (P<0.05). Despite reduced regional blood flows in HIB hearts, ATP content in the LAD region, when normalized to the remote region was similar in HIB versus SWOP (1.06±0.06 and 1.02±0.05 respectively; NS) as was the transmural phosphocreatine (PCr) to ATP ratio (2.1±0.2 and 2.2±0.2 respectively; NS). Using iTRAQ, 64 common proteins were identified in HIB and SWOP hearts. Compared with SWOP, the relative abundance of mitochondrial proteins involved with electron transport chain (ETC) were reduced in HIB including NADH dehydrogenase, Cytochrome c reductase and oxidase, ATP synthase, and nicotinamide nucleotide transhydrogenase. Within chronically HIB heart tissue with reduced blood flow, the relative abundance of mitochondrial ETC proteins is decreased when compared with SWOP tissue. These data support the concept that HIB heart tissue subjected to chronically reduced blood flow is associated with a down-regulation in the expression of key mitochondrial proteins involved in electron transport.
Asunto(s)
Proteínas del Complejo de Cadena de Transporte de Electrón/biosíntesis , Regulación Enzimológica de la Expresión Génica , Precondicionamiento Isquémico Miocárdico , Mitocondrias Cardíacas/enzimología , Proteínas Mitocondriales/biosíntesis , Proteínas Musculares/biosíntesis , Miocardio/enzimología , Animales , Circulación Coronaria , Femenino , Masculino , Mitocondrias Cardíacas/patología , Miocardio/patología , Necrosis/enzimología , Necrosis/genética , PorcinosRESUMEN
Carbonylation is the covalent, non-reversible modification of the side chains of cysteine, histidine, and lysine residues by lipid peroxidation end products such as 4-hydroxy- and 4-oxononenal. In adipose tissue the effects of such modifications are associated with increased oxidative stress and metabolic dysregulation centered on mitochondrial energy metabolism. To address the role of protein carbonylation in the pathogenesis of mitochondrial dysfunction, quantitative proteomics was employed to identify specific targets of carbonylation in GSTA4-silenced or overexpressing 3T3-L1 adipocytes. GSTA4-silenced adipocytes displayed elevated carbonylation of several key mitochondrial proteins including the phosphate carrier protein, NADH dehydrogenase 1α subcomplexes 2 and 3, translocase of inner mitochondrial membrane 50, and valyl-tRNA synthetase. Elevated protein carbonylation is accompanied by diminished complex I activity, impaired respiration, increased superoxide production, and a reduction in membrane potential without changes in mitochondrial number, area, or density. Silencing of the phosphate carrier or NADH dehydrogenase 1α subcomplexes 2 or 3 in 3T3-L1 cells results in decreased basal and maximal respiration. These results suggest that protein carbonylation plays a major instigating role in cytokine-dependent mitochondrial dysfunction and may be linked to the development of insulin resistance in the adipocyte.
Asunto(s)
Adipocitos/metabolismo , Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Carbonilación Proteica/fisiología , Células 3T3-L1 , Adipocitos/citología , Animales , Silenciador del Gen , Resistencia a la Insulina/fisiología , Ratones , Mitocondrias/genética , Proteínas Mitocondriales/genética , Consumo de Oxígeno/fisiologíaRESUMEN
Oxidative stress is linked to the production of reactive lipid aldehydes that non-enzymatically alkylate cysteine, histidine, or lysine residues in a reaction termed protein carbonylation. Reactive lipid aldehydes and their derivatives are detoxified via a variety of phase I and phase II systems, and when antioxidant defenses are compromised or oxidative conditions are increased, protein carbonylation is increased. The resulting modification has been implicated as causative in a variety of metabolic states including neurodegeneration, muscle wasting, insulin resistance, and aging. Although such modifications usually result in loss of protein function, protein carbonylation may be regulatory and activate signaling pathways involved in antioxidant biology and cellular homeostasis.
Asunto(s)
Homeostasis , Metabolismo , Carbonilación Proteica/fisiología , Envejecimiento , Aldehídos/metabolismo , Antioxidantes , Humanos , Resistencia a la Insulina , Metabolismo de los Lípidos , Fase I de la Desintoxicación Metabólica/fisiología , Fase II de la Desintoxicación Metabólica/fisiología , Atrofia Muscular , Degeneración Nerviosa , Oxidación-Reducción , Estrés OxidativoRESUMEN
Obesity results in increased macrophage recruitment to adipose tissue that promotes a chronic low-grade inflammatory state linked to increased fatty acid efflux from adipocytes. Activated macrophages produce a variety of pro-inflammatory lipids such as leukotriene C4 (LTC4) and 5-, 12-, and 15-hydroxyeicosatetraenoic acid (HETE) suggesting the hypothesis that fatty acids may stimulate eicosanoid synthesis. To assess if eicosanoid production increases with obesity, adipose tissue of leptin deficient ob/ob mice was analyzed. In ob/ob mice, LTC4 and 12-HETE levels increased in the visceral (but not subcutaneous) adipose depot while the 5-HETE levels decreased and 15-HETE abundance was unchanged. Since macrophages produce the majority of inflammatory molecules in adipose tissue, treatment of RAW264.7 or primary peritoneal macrophages with free fatty acids led to increased secretion of LTC4 and 5-HETE, but not 12- or 15-HETE. Fatty acid binding proteins (FABPs) facilitate the intracellular trafficking of fatty acids and other hydrophobic ligands and in vitro stabilize the LTC4 precursor leukotriene A4 (LTA4) from non-enzymatic hydrolysis. Consistent with a role for FABPs in LTC4 synthesis, treatment of macrophages with HTS01037, a specific FABP inhibitor, resulted in a marked decrease in both basal and fatty acid-stimulated LTC4 secretion but no change in 5-HETE production or 5-lipoxygenase expression. These results indicate that the products of adipocyte lipolysis may stimulate the 5-lipoxygenase pathway leading to FABP-dependent production of LTC4 and contribute to the insulin resistant state.
RESUMEN
Lipid peroxidation yields multiple aldehyde species. Of these, trans-4-hydroxy-2-nonenal (HNE), derived from n-6 poly-unsaturated fatty acids (PUFA) is one of the most studied products of lipid peroxidation. On the other hand, oxidative damage to n-3 PUFA, e.g. docosahexaenoic acid (DHA; 22:6, n-3) and eicosapentaenoic acid, is now recognized as an important effector of oxidative stress and is of particular interest in n-3 rich tissues such as brain and retina. Trans-4-hydroxy-2-hexenal (HHE) is a major alpha,beta-unsaturated aldehyde product of n-3 PUFA oxidation and, like HNE, is an active biochemical mediator resulting from lipid peroxidation. HHE adducts are elevated in disease states, in some cases, at higher levels than the corresponding HNE adduct. HHE has properties in common with HNE, but there are important differences particularly with respect to adduction targets and detoxification pathways. In this review, the biochemistry and cell biology of HHE will be discussed. From this review, it is clear that further study is needed to determine the biochemical and physiological roles of HHE and its related aldehyde, trans-4-oxo-2-hexenal.
Asunto(s)
Aldehídos/metabolismo , Peroxidación de Lípido , Estrés Oxidativo , Transducción de Señal , Aldehídos/química , Animales , Apoptosis , Encéfalo/metabolismo , Ácidos Docosahexaenoicos/metabolismo , Ácido Eicosapentaenoico/metabolismo , Aceites de Pescado/metabolismo , Humanos , Fase I de la Desintoxicación Metabólica , Retina/metabolismoRESUMEN
Ethanol withdrawal increases lipid peroxidation of the polyunsaturated fatty acid (PUFA) docosahexaenoate (22:6; n-3) in the CNS. To further define the role of oxidative damage of PUFAs during ethanol withdrawal, we measured the levels of glutathione adducts of 4-hydroxy-2-hexenal (GSHHE) and 4-hydroxy-2-nonenal (GSHNE) as biomarkers of brain lipid peroxidation of n-3 and n-6 PUFAs, respectively. In this study rats received an ethanol-containing diet for 6 weeks followed by withdrawal ranging from 0 to 7 days. GSHHE content was elevated (>350%) in the cerebral cortex after 2 days of withdrawal with no change in GSHNE. The levels of GSHHE were significantly greater (2- to 20-fold) than those of GSHNE in multiple brain regions. Experiments demonstrated that intoxication and withdrawal did not alter the enzymatic rate of formation of GSHHE or GSHNE, but the rate of formation of GSHHE was higher (approximately 50%) than that of GSHNE. These results indicate that selective oxidative damage to n-3 PUFAs occurs in the cerebral cortex as a result of ethanol withdrawal and that 4-hydroxy-2-hexenal is metabolized to the GSH adduct more efficiently than HNE.
Asunto(s)
Aldehídos/metabolismo , Corteza Cerebral/metabolismo , Etanol/metabolismo , Glutatión/química , Glutatión/metabolismo , Animales , Encéfalo/metabolismo , Cromatografía Liquida , Ácidos Grasos/metabolismo , Peroxidación de Lípido , Masculino , Ratas , Ratas Sprague-Dawley , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
alpha,beta-unsaturated aldehydes are toxic products of lipid peroxidation. Detection and characterization of these aldehydes is important in many human disease states as well as in the food industry. Our study shows that electron ionization-mass spectrometry (EI-MS) and positive-ion chemical ionization-mass spectrometry (PICI-MS), but not electron capture negative ionization-mass spectrometry (ECNI-MS), can be used to detect the C4-hydroxylation state of alpha,beta-unsaturated aldehydes derivatized with pentafluorobenzyl hydroxylamine alone. EI-MS and PICI-MS spectra of 4-hydroxy-2-alkenals contained a fragment with m/z 252, whereas spectra of 2-alkenals contained a fragment with m/z 250. These fragments are consistent with fragmentation between C3 and C4 with transfer of two hydrogens from C4 and the C4 hydroxyl group in the case of 4-hydroxy-2-alkenals. In addition, EI-MS and PICI-MS were able to distinguish 4-hydroxy-2-alkenals and 2-alkenals from 4-keto-2-alkenals and 4-hydroxyalkanals. On the other hand, ECNI-MS provided complex spectra regarding C4-hydroxylation state. Furthermore, the syn- and anti-configurations of PFB-oximes had different resultant spectra using ECNI-MS, but not with EI-MS or PICI-MS. These data indicate that EI-MS and PICI-MS are more amenable for structural analysis of alpha,beta-unsaturated aldehydes than ECNI-MS.
Asunto(s)
Aldehídos/análisis , Aldehídos/química , Cromatografía de Gases y Espectrometría de Masas/métodos , Espectrometría de Masa por Ionización de Electrospray/métodos , Estructura MolecularRESUMEN
Lipid peroxidation of docosahexaenoic (22:6; n-3) acid (DHA) is elevated in the CNS in patients with Alzheimer's disease and in animal models of seizure and ethanol withdrawal. One product of DHA oxidation is trans-4-hydroxy-2-hexenal (HHE), a six carbon analog of the n-6 fatty acid derived trans-4-hydroxy-2-nonenal (HNE). In this work, we studied the neurotoxic potential of HHE. HHE and HNE were toxic to primary cultures of cerebral cortical neurons with LD(50)'s of 23 and 18 micromol/L, respectively. Toxicity was prevented by the addition of thiol scavengers. HHE and HNE depleted neuronal GSH content identically with depletion observed with 10 micromol/L of either compound. Using an antibody raised against HHE-protein adducts, we show that HHE modified specific proteins of 75, 50, and 45 kDa in concentration- and time-dependent manners. The time-dependent formation of HHE differed from that of F4-neuroprostanes following in vitro DHA oxidation likely as a result of the different oxidation pathways involved. Using purified mitochondrial aldehyde dehydrogenase ALDH5A, we found that HHE was oxidized 6.5-fold less efficiently than HNE. Our data demonstrate that HHE and HNE have similarities but also differences in their neurotoxic mechanisms and metabolism.