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Female mice display greater adipose angiogenesis and maintain healthier adipose tissue than do males upon high-fat diet feeding. Through transcriptome analysis of endothelial cells (EC) from the white adipose tissue of male and female mice high-fat-fed for 7 weeks, we found that adipose EC exhibited pronouncedly sex-distinct transcriptomes. Genes upregulated in female adipose EC were associated with proliferation, oxidative phosphorylation, and chromatin remodeling contrasting the dominant enrichment for genes related to inflammation and a senescence-associated secretory of male EC. Similar sex-biased phenotypes of adipose EC were detectable in a dataset of aged EC. The highly proliferative phenotype of female EC was observed also in culture conditions. In turn, male EC displayed greater inflammatory potential than female EC in culture, based on basal and tumor necrosis factor alpha-stimulated patterns of gene expression. Our study provides insights into molecular programs that distinguish male and female EC responses to pathophysiological conditions.
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Exercise is one of the only nonpharmacological remedies known to counteract genetic and chronic diseases by enhancing health and improving life span. Although the many benefits of regular physical activity have been recognized for some time, the intricate and complex signaling systems triggered at the onset of exercise have only recently begun to be uncovered. Exercising muscles initiate a coordinated, multisystemic, metabolic rewiring, which is communicated to distant organs by various molecular mediators. The field of exercise research has been expanding beyond the musculoskeletal system, with interest from industry to provide realistic models and exercise mimetics that evoke a whole body rejuvenation response. The 18th International Biochemistry of Exercise conference took place in Toronto, Canada, from May 25 to May 28, 2022, with more than 400 attendees. Here, we provide an overview of the most cutting-edge exercise-related research presented by 66 speakers, focusing on new developments in topics ranging from molecular and cellular mechanisms of exercise adaptations to exercise therapy and management of disease and aging. We also describe how the manipulation of these signaling pathways can uncover therapeutic avenues for improving human health and quality of life.
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Exercício Físico , Qualidade de Vida , Humanos , Exercício Físico/fisiologia , Adaptação Fisiológica , Envelhecimento/fisiologia , Terapia por Exercício , Músculo Esquelético/metabolismoRESUMO
Adipose tissue depots are invested with an extensive capillary network that is closely associated with maintenance of adipose functions and enables healthy tissue expansion. The capillary network displays a high level of plasticity, demonstrating either growth (angiogenesis) or regression (rarefaction) under various physiological/pathological conditions, which has significant consequences for cardiometabolic health. Thus, the visualization and quantification of adipose vascular networks is an important aspect of studying factors that regulate adipose tissue health. This chapter provides an overview of several methods to quantify adipose vascularization. In-depth protocols are provided for the visualization of vascular structures by staining and imaging of whole-mount adipose tissues or paraffin-embedded adipose tissue sections, together with the quantitative analysis of vascularization from these images.
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Tecido Adiposo , Neovascularização Patológica , Tecido Adiposo/irrigação sanguínea , Humanos , Neovascularização Fisiológica , Coloração e RotulagemRESUMO
Risk factors for cardiovascular diseases trigger molecular changes that harm the endothelial cells in the heart, but exercise can suppress these effects.
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Doenças Cardiovasculares , Animais , Doenças Cardiovasculares/epidemiologia , Células Endoteliais , Endotélio Vascular , Coração , Camundongos , Fatores de RiscoRESUMO
Diabetes promotes an angiostatic phenotype in the microvascular endothelium of skeletal muscle and skin. Angiogenesis-related microRNAs (angiomiRs) regulate angiogenesis through the translational repression of pro- and anti-angiogenic genes. The maturation of micro-RNA (miRs), including angiomiRs, requires the action of DROSHA and DICER proteins. While hyperglycemia modifies the expression of angiomiRs, it is unknown whether high glucose conditions alter the maturation process of angiomiRs in dermal and skeletal muscle microvascular endothelial cells (MECs). Compared to 5 mM of glucose, high glucose condition (30 mM, 6-24 h) decreased DROSHA protein expression, without changing DROSHA mRNA, DICER mRNA, or DICER protein in primary dermal MECs. Despite DROSHA decreasing, high glucose enhanced the maturation and expression of one angiomiR, miR-15a, and downregulated an miR-15a target: Vascular Endothelial Growth Factor-A (VEGF-A). The high glucose condition increased Murine Double Minute-2 (MDM2) expression and MDM2-binding to DROSHA. Inhibition of MDM2 prevented the effects evoked by high glucose on DROSHA protein and miR-15a maturation in dermal MECs. In db/db mice, blood glucose was negatively correlated with the expression of skeletal muscle DROSHA protein, and high glucose decreased DROSHA protein in skeletal muscle MECs. Altogether, our results suggest that high glucose reduces DROSHA protein and enhances the maturation of the angiostatic miR-15a through a mechanism that requires MDM2 activity.
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Células Endoteliais/metabolismo , Glucose/toxicidade , MicroRNAs/genética , Microvasos/patologia , Neovascularização Fisiológica/genética , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Ribonuclease III/metabolismo , Animais , Células Cultivadas , Células Endoteliais/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Masculino , Manitol/farmacologia , Camundongos Endogâmicos C57BL , MicroRNAs/metabolismo , Neovascularização Fisiológica/efeitos dos fármacos , Pressão Osmótica/efeitos dos fármacos , Ligação Proteica/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-mdm2/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Fatores de Tempo , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Pericytes are mural vascular cells found predominantly on the abluminal wall of capillaries, where they contribute to the maintenance of capillary structural integrity and vascular permeability. Generally quiescent cells in the adult, pericyte activation and proliferation occur during both physiological and pathological vascular and tissue remodeling. A considerable body of research indicates that pericytes possess attributes of a multipotent adult stem cell, as they are capable of self-renewal as well as commitment and differentiation into multiple lineages. However, pericytes also display phenotypic heterogeneity and recent studies indicate that lineage potential differs between pericyte subpopulations. While numerous microenvironmental cues and cell signaling pathways are known to regulate pericyte functions, the roles that metabolic pathways play in pericyte quiescence, self-renewal or differentiation have been given limited consideration to date. This review will summarize existing data regarding pericyte metabolism and will discuss the coupling of signal pathways to shifts in metabolic pathway preferences that ultimately regulate pericyte quiescence, self-renewal and trans-differentiation. The association between dysregulated metabolic processes and development of pericyte pathologies will be highlighted. Despite ongoing debate regarding pericyte classification and their functional capacity for trans-differentiation in vivo, pericytes are increasingly exploited as a cell therapy tool to promote tissue healing and regeneration. Ultimately, the efficacy of therapeutic approaches hinges on the capacity to effectively control/optimize the fate of the implanted pericytes. Thus, we will identify knowledge gaps that need to be addressed to more effectively harness the opportunity for therapeutic manipulation of pericytes to control pathological outcomes in tissue remodeling.
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AIM: Critical limb ischaemia (CLI) is characterized by inadequate angiogenesis, arteriolar remodelling and chronic myopathy, which are most severe in type 2 diabetic patients. Hypertriglyceridaemia, commonly observed in these patients, compromises macrovascular function. However, the effects of high-fat diet-induced increases in circulating lipids on microvascular remodelling are not established. Here, we investigated if high-fat diet would mimic the detrimental effect of type 2 diabetes on post-ischaemia vascular remodelling and muscle regeneration, using a mouse model of hindlimb ischaemia. METHODS: Male C57Bl6/J mice were fed with normal or high-fat diets for 8 weeks prior to unilateral femoral artery ligation. Laser doppler imaging was used to assess limb perfusion recovery. Vascular recovery, inflammation, myofibre regeneration and fibrosis were assessed at 4 or 14 days post-ligation by histology and RNA analyses. Capillary-level haemodynamics were assessed by intravital microscopy of control and regenerating muscles 14 days post-ligation. RESULTS: High-fat diet increased muscle succinate dehydrogenase activity and capillary-level oxygen supply. At 4 days post-ligation, no diet differences were detected in muscle damage, inflammatory infiltration or capillary activation. At 14 days post-ligation, high fat-fed mice displayed accelerated limb blood flow recovery, elevated capillary and arteriole densities as well as greater red blood cell supply rates and capillary-level oxygen supply. Regenerating muscles from high fat-fed mice displayed lower interstitial fat and collagen deposition. CONCLUSION: The muscle-level adaptations to high-fat diet improved multiple aspects of muscle recovery in response to ischaemia and did not recapitulate the worse outcomes seen in diabetic CLI patients.
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Dieta Hiperlipídica , Isquemia , Microcirculação , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/fisiologia , Neovascularização Fisiológica , Regeneração , Animais , Diabetes Mellitus Tipo 2 , Modelos Animais de Doenças , Membro Posterior , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fluxo Sanguíneo RegionalRESUMO
Skeletal muscle capillarity is characteristically reduced in mature leptin receptor-deficient (Leprdb) mice, which has been attributed to the capillary loss that occurs secondary to metabolic dysfunction. Despite wide recognition of leptin as a pro-angiogenic molecule, the contribution of this adipokine has largely been overlooked in peripheral tissues. Moreover, prior documentation of leptin production within skeletal muscle indicates a potential paracrine role in maintaining local tissue homeostasis. Thus, we hypothesized that leptin is a physiological local paracrine regulator of skeletal muscle angiogenesis and that its production may be modulated by nutrient availability. Leprdb mice exhibited impaired angiogenesis during normal developmental maturation of skeletal myocytes, corresponding with an inability to increase vascular endothelial growth factor-A (VEGFA) mRNA and protein levels between 4 and 13 weeks. In cultured murine and human skeletal myocytes, recombinant leptin increased VEGFA mRNA levels. Leptin mRNA was detectable in skeletal muscle, increasing with prolonged high-fat feeding in mice, and with adiposity in human subjects. Platelet-derived growth factor receptor (PDGFR)α- and PDGFRß- expressing perivascular cell populations were identified as leptin producing within skeletal muscle of mice and humans. Furthermore, in response to 2 weeks of high-fat feeding, PDGFRß+ but not PDGFRα+ cells increased leptin production. We conclude that leptin is a physiological regulator of the capillary network in skeletal muscle and stimulates VEGFA production by skeletal myocytes. PDGFRß expressing perivascular cells exhibit the capacity to act as local "nutrient-sensors" that couple nutrient status to leptin production in skeletal muscle.
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Leptina/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Neovascularização Fisiológica , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Animais , Humanos , Leptina/genética , Camundongos , Camundongos Mutantes , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Receptor beta de Fator de Crescimento Derivado de Plaquetas/genética , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Impaired angiogenesis is a hallmark of metabolically dysfunctional adipose tissue in obesity. However, the underlying mechanisms restricting angiogenesis within this context remain ill-defined. Here, we demonstrate that induced endothelial-specific depletion of the transcription factor Forkhead Box O1 (FoxO1) in male mice led to increased vascular density in adipose tissue. Upon high-fat diet feeding, endothelial cell FoxO1-deficient mice exhibited even greater vascular remodeling in the visceral adipose depot, which was paralleled with a healthier adipose tissue expansion, higher glucose tolerance and lower fasting glycemia concomitant with enhanced lactate levels. Mechanistically, FoxO1 depletion increased endothelial proliferative and glycolytic capacities by upregulating the expression of glycolytic markers, which may account for the improvements at the tissue level ultimately impacting whole-body glucose metabolism. Altogether, these findings reveal the pivotal role of FoxO1 in controlling endothelial metabolic and angiogenic adaptations in response to high-fat diet and a contribution of the endothelium to whole-body energy homeostasis.
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Endotélio Vascular/crescimento & desenvolvimento , Endotélio Vascular/metabolismo , Proteína Forkhead Box O1/deficiência , Obesidade/metabolismo , Animais , Dieta Hiperlipídica , Proteína Forkhead Box O1/metabolismo , Glucose/metabolismo , Glicólise , Homeostase , Gordura Intra-Abdominal/irrigação sanguínea , Gordura Intra-Abdominal/metabolismo , Masculino , Camundongos Knockout , Microvasos/metabolismo , Modelos Biológicos , Músculo Esquelético/irrigação sanguínea , Obesidade/sangue , Tamanho do Órgão , Especificidade de Órgãos , Fenótipo , Triglicerídeos/sangue , Regulação para Cima , Remodelação VascularRESUMO
Background: Impaired capillary growth (angiogenesis) in skeletal muscle and adipose tissue contributes to the development of metabolic disorders in obese males. This association remains unexplored in females, despite mounting evidence that endothelial cells have sex-specific transcriptional profiles. Therefore, herein we assessed whether males and females show distinct angiogenic capacities in response to diet-induced obesity. Methods: Age-matched male and female mice were fed normal chow or high-fat obesogenic diets for 16 weeks. At the end of diet period, systemic glucose disposal was assessed as well as insulin sensitivity of skeletal muscle and visceral adipose tissue. Capillary content and the expression of angiogenic regulators were also evaluated in these tissues. Results: When placed on a high-fat diet, female mice gained less weight than males and showed a metabolic phenotype similar to NC-fed mice, contrasting with the impaired whole-body glucose metabolism observed in high-fat-fed males. However, high-fat-feeding elevated serum lipid levels similarly in male and female mice. Although skeletal muscle of high-fat-fed female mice had higher insulin sensitivity than male counterparts, no sex difference was detected in muscle capillarization. Metabolic functions of perigonadal white adipose tissue (pgWAT) were retained in high-fat-fed females, as evidenced by smaller adipocytes with preserved insulin sensitivity, greater responsiveness to isoproterenol, higher expression of Adiponectin and a lower ratio of Leptin:Adiponectin mRNA. An enhanced browning phenotype was detected in HF-fed female adipocytes with upregulation of Ucp1 expression. PgWAT from high-fat-fed females also showed augmented capillary number and expression of endothelial cell markers, which was associated with elevated mRNA levels of pro-angiogenic mediators, including vascular endothelial growth factor A (Vegfa) and its receptor (Vegfr2), the Notch ligand Jagged-1 (Jag1) and Angiopoietin-2 (Angpt2). Conclusion: Taken together, our findings provide novel evidence that visceral adipose tissue of female mice display greater levels of pro-angiogenic factors and vascularity than males in response to high-fat diet. This phenotype is associated with preserved metabolic homeostasis at both tissue and systemic levels. Our study discloses that a thus-far-unappreciated sex-specific difference in the regulation of adipose angiogenesis may contribute to an individual's susceptibility to developing adipose dysfunction and obesity-related metabolic disturbances.
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Sustained elevations in circulating glucocorticoids elicit reductions in skeletal muscle microvascular content, but little is known of the underlying mechanisms. We hypothesized that glucocorticoid-induced oxidative stress contributes to this phenomenon. In rats that were implanted with corticosterone (CORT) or control pellets, CORT caused a significant decrease in muscle glutathione levels and a corresponding increase in protein carbonylation, an irreversible oxidative modification of proteins. Decreased endothelial nitric oxide synthase and increased endothelin-1 mRNA levels were detected after 9 days of CORT, and blood flow to glycolytic muscles was diminished. Control and CORT rats were treated concurrently with drinking water containing the superoxide dismutase mimetic tempol (172 mg/L) or the α-1 adrenergic receptor antagonist prazosin (50 mg/L) for 6 or 16 days. Both tempol and prazosin alleviated skeletal muscle protein carbonylation. Tempol failed to prevent CORT-mediated capillary rarefaction and was ineffective in restoring skeletal muscle blood flow. In contrast, prazosin blocked capillary rarefaction and restored skeletal muscle blood flow to control levels. The failure of tempol to prevent CORT-induced skeletal muscle microvascular rarefaction does not support a dominant role of superoxide-induced oxidative stress in this process. Although a decrease in protein carbonylation was observed with prazosin treatment, our data suggest that the maintenance of skeletal muscle microvascular content is related more closely with counteracting the CORT-mediated influence on skeletal muscle vascular tone.
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Corticosterona/metabolismo , Óxidos N-Cíclicos/administração & dosagem , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/metabolismo , Estresse Oxidativo , Superóxido Dismutase/metabolismo , Antagonistas de Receptores Adrenérgicos alfa 1/administração & dosagem , Animais , Capilares , Corticosterona/administração & dosagem , Masculino , Músculo Esquelético/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Prazosina/administração & dosagem , Ratos Sprague-Dawley , Marcadores de Spin , Superóxido Dismutase/administração & dosagem , Vasoconstrição/efeitos dos fármacosRESUMO
Remodeling of the skeletal muscle microvasculature involves the coordinated actions of matrix metalloproteinases (MMPs) and their endogenous inhibitors, tissue inhibitor of metalloproteinases (TIMPs). We hypothesized that the loss of TIMP1 would enhance both ischemia and flow-induced vascular remodeling by increasing MMP activity. TIMP1 deficient (Timp1-/- ) and wild-type (WT) C57BL/6 mice underwent unilateral femoral artery (FA) ligation or were treated with prazosin, an alpha-1 adrenergic receptor antagonist, in order to investigate vascular remodeling to altered flow. Under basal conditions, Timp1-/- mice had reduced microvascular content as compared to WT mice. Furthermore, vascular remodeling was impaired in Timp1-/- mice. Timp1-/- mice displayed reduced blood flow recovery in response to FA ligation and no arteriogenic response to prazosin treatment. Timp1-/- mice failed to undergo angiogenesis in response to ischemia or prazosin, despite maintaining the capacity to increase VEGF-A and eNOS mRNA. Vascular permeability was increased in muscles of Timp1-/- mice in response to both prazosin treatment and FA ligation, but this was not accompanied by greater MMP activity. This study highlights a previously undescribed integral role for TIMP1 in both vascular network maturation and adaptations to ischemia or alterations in flow. J. Cell. Physiol. 232: 831-841, 2017. © 2016 Wiley Periodicals, Inc.
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Adaptação Fisiológica , Circulação Sanguínea/fisiologia , Inibidor Tecidual de Metaloproteinase-1/metabolismo , Adaptação Fisiológica/efeitos dos fármacos , Animais , Circulação Sanguínea/efeitos dos fármacos , Permeabilidade Capilar/efeitos dos fármacos , Extremidades/irrigação sanguínea , Extremidades/patologia , Artéria Femoral/efeitos dos fármacos , Artéria Femoral/patologia , Isquemia/patologia , Ligadura , Metaloproteinases da Matriz/metabolismo , Camundongos Endogâmicos C57BL , Microvasos/efeitos dos fármacos , Microvasos/metabolismo , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/efeitos dos fármacos , Prazosina/farmacologia , Inibidor Tecidual de Metaloproteinase-1/deficiência , Inibidor Tecidual de Metaloproteinase-1/genética , Remodelação Vascular/efeitos dos fármacosRESUMO
Type-1 diabetes mellitus (T1D) causes impairments within the skeletal muscle microvasculature. Both regular exercise and prazosin have been shown to improve skeletal muscle capillarization and metabolism in healthy rats through distinct angiogenic mechanisms. The aim of this study was to evaluate the independent and additive effects of voluntary exercise and prazosin treatment on capillary-to-fiber ratio (C:F) in streptozotocin (STZ)-treated diabetic rats. STZ (65 mg/kg) was intraperitoneally administered to male Sprague-Dawley rats (n = 36) to induce diabetes, with healthy, nondiabetic, sedentary rats (n = 10) as controls. The STZ-treated rats were then divided into sedentary (SED) or exercising (EX; 24-h access to running wheels) groups and then further subdivided into prazosin (Praz) or water (H2O) treatment groups: nondiabetic-SED-H2O, STZ-SED-H2O, STZ-EX-H2O, STZ-SED-Praz, and STZ-EX-Praz. After 3 wk, untreated diabetes significantly reduced the C:F in tibialis anterior (TA) and soleus muscles in the STZ-SED-H2O animals (both P < 0.05). Voluntary exercise and prazosin treatment independently resulted in a normalization of C:F within the TA (1.86 ± 0.12 and 2.04 ± 0.03 vs 1.71 ± 0.09, P < 0.05) and the soleus (2.36 ± 0.07 and 2.68 ± 0.14 vs 2.13 ± 0.12, P < 0.05). The combined STZ-EX-Praz group resulted in the highest C:F within the TA (2.26 ± 0.07, P < 0.05). Voluntary exercise volume was negatively correlated with fed blood glucose levels (r2 = -0.7015, P < 0.01) and, when combined with prazosin, caused further enhanced nonfasted glucose (P < 0.01). Exercise and prazosin reduced circulating nonesterified fatty acids more than either stimulus alone (P < 0.05). These results suggest that the distinct stimulation of angiogenesis, with both regular exercise and prazosin treatment, causes a cooperative improvement in the microvascular complications associated with T1D.NEW & NOTEWORTHY It is currently well established that poorly controlled diabetes reduces both skeletal muscle mass and muscle capillarization. These muscle-specific features of diabetes may, in turn, compromise insulin sensitivity and glucose control. Using a model of streptozotocin-induced diabetes, we show the vascular complications linked with disease and how chronic exposure to exercise and prazosin (an α1-adrenergic antagonist) can reduce these complications and improve glycemic control.
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Diabetes Mellitus Experimental/fisiopatologia , Diabetes Mellitus Experimental/terapia , Terapia por Exercício , Rarefação Microvascular/fisiopatologia , Rarefação Microvascular/terapia , Prazosina/uso terapêutico , Antagonistas de Receptores Adrenérgicos alfa 1/farmacologia , Antagonistas de Receptores Adrenérgicos alfa 1/uso terapêutico , Animais , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Terapia Combinada , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/tratamento farmacológico , Angiopatias Diabéticas/induzido quimicamente , Angiopatias Diabéticas/fisiopatologia , Angiopatias Diabéticas/terapia , Hipoglicemiantes/farmacologia , Hipoglicemiantes/uso terapêutico , Masculino , Rarefação Microvascular/induzido quimicamente , Rarefação Microvascular/tratamento farmacológico , Prazosina/farmacologia , Ratos , Ratos Sprague-Dawley , Estreptozocina , Resultado do Tratamento , VoliçãoRESUMO
High-dose glucocorticoids (GC) induce skeletal muscle atrophy, insulin resistance, and reduced muscle capillarization. Identification of treatments to prevent or reverse capillary rarefaction and metabolic deterioration caused by prolonged elevations in GCs would be therapeutically beneficial. Chronic administration of prazosin, an α1-adrenergic antagonist, increases skeletal muscle capillarization in healthy rodents and, recently, in a rodent model of elevated GCs and hyperglycemia. The purpose of this study was to determine whether prazosin administration would improve glucose tolerance and insulin sensitivity, through prazosin-mediated sparing of capillary rarefaction, in this rodent model of increased GC exposure. Prazosin was provided in drinking water (50 mg/l) to GC-treated or control rats (400 mg implants of either corticosterone or a wax pellet) for 7 or 14 days (n = 5-14/group). Whole body measures of glucose metabolism were correlated with skeletal muscle capillarization (C:F) at 7 and 14 days in the four groups of rats. Individual C:F was found to be predictive of insulin sensitivity (r2 = 0.4781), but not of glucose tolerance (r2 = 0.1601) and compared with water only, prazosin treatment decreased insulin values during oral glucose challenge by approximately one-third in corticosterone (Cort)-treated animals. Cort treatment, regardless of duration, induced significant glycolytic skeletal muscle atrophy (P < 0.05), decreased IRS-1 protein content (P < 0.05), and caused elevations in FOXO1 protein expression (P < 0.05), which were unaffected with prazosin administration. In summary, it appears that α1-adrenergic antagonism improves Cort-induced skeletal muscle vascular impairments and reduces insulin secretion during an oral glucose tolerance test, but is unable to improve the negative alterations directly affecting the myocyte, including muscle size and muscle signaling protein expression.
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Capilares/efeitos dos fármacos , Glucocorticoides/administração & dosagem , Resistência à Insulina/fisiologia , Insulina/metabolismo , Músculo Esquelético/metabolismo , Prazosina/administração & dosagem , Antagonistas de Receptores Adrenérgicos alfa 1/administração & dosagem , Animais , Capilares/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Glucose/farmacocinética , Masculino , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/efeitos dos fármacos , Ratos , Ratos Sprague-DawleyRESUMO
Glucocorticoids (GC) elicit skeletal muscle capillary rarefaction, which can subsequently impair blood distribution and muscle function; however, the mechanisms have not been established. We hypothesized that CORT would inhibit endothelial cell survival signals but that treatment with the alpha-1 adrenergic receptor inhibitor prazosin, which leads to angiogenesis in skeletal muscle of healthy rats, would reverse these effects and induce angiogenesis within the skeletal muscle of corticosterone (CORT)-treated rats. Male Sprague Dawley rats were implanted subcutaneously with CORT pellets (400 mg/rat), with or without concurrent prazosin treatment (50mg/L in drinking water), for 1 or 2 weeks. Skeletal muscle capillary rarefaction, as indicated by a significant reduction in capillary-to-fiber ratio (C:F), occurred after 2 weeks of CORT treatment. Concurrent prazosin administration prevented this capillary rarefaction in CORT-treated animals but did not induce angiogenesis or arteriogenesis as was observed with prazosin treatment in control rats. CORT treatment reduced the mRNA level of Angiopoietin-1 (Ang-1), which was partially offset in the muscles of rats that received 2 weeks of co-treatment with prazosin. In 2W CORT animals, prazosin treatment elicited a significant increase in vascular endothelial growth factor-A (VEGF-A) mRNA and protein. Conversely prazosin did not rescue CORT-induced reductions in transforming growth factor beta-1 (TGFß1 and matrix metalloproteinase-2 (MMP-2) mRNA. To determine if CORT impaired shear stress dependent signaling, cultured rat skeletal muscle endothelial cells were pre-treated with CORT (600nM) for 48 hours, then exposed to 15 dynes/cm2 shear stress or maintained with no flow. CORT blunted the shear stress-induced increase in pSer473 Akt, while pThr308 Akt, ERK1/2 and p38 phosphorylation and nitric oxide (NO) production were unaffected. This study demonstrates that GC-mediated capillary rarefaction is associated with a reduction in Ang-1 mRNA within the skeletal muscle microenvironment and that concurrent prazosin treatment effectively increases VEGF-A levels and prevents capillary loss.
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Capilares/efeitos dos fármacos , Capilares/patologia , Glucocorticoides/efeitos adversos , Prazosina/farmacologia , Substâncias Protetoras/farmacologia , Indutores da Angiogênese/metabolismo , Angiopoietina-1/genética , Angiopoietina-1/metabolismo , Animais , Biomarcadores , Capilares/metabolismo , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Expressão Gênica , Glucocorticoides/sangue , Masculino , Camundongos , Modelos Animais , Músculo Esquelético/irrigação sanguínea , Mioblastos/efeitos dos fármacos , Mioblastos/metabolismo , Ratos , Estresse Mecânico , Trombospondina 1/genética , Trombospondina 1/metabolismo , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Skeletal muscle microvascular dysfunction contributes to disease severity in type 2 diabetes. Recent studies indicate a role for Forkhead box O (FoxO) transcription factors in modulating endothelial cell phenotype. We hypothesized that a high-fat (HF) diet generates a dysfunctional vascular niche through an increased expression of endothelial FoxO. FoxO1 protein increased (+130%) in the skeletal muscle capillaries from HF compared to normal chow-fed mice. FoxO1 protein was significantly elevated in cultured endothelial cells exposed to the saturated fatty acid palmitate or the proinflammatory cytokine TNF-α. In HF-fed mice, endothelium-directed depletion of FoxO1/3/4 (FoxO(Δ)) improved insulin sensitivity (+110%) compared to that of the controls (FoxO(L/L)). The number of skeletal muscle capillaries increased significantly in the HF-FoxO(Δ) mice. Transcript profiling of skeletal muscle identified significant increases in genes associated with angiogenesis and lipid metabolism in HF-FoxO(Δ) vs. HF-FoxO(L/L) mice. HF-FoxO(Δ) muscle also was characterized by a decrease in inflammation-related genes and an enriched M2 macrophage signature. We conclude that endothelial FoxO proteins promote insulin resistance in HF diet, which may in part result from FoxO proteins establishing an antiangiogenic and proinflammatory microenvironment within skeletal muscle. These findings provide mechanistic insight into the development of microvascular dysfunction in the progression of type 2 diabetes.-Nwadozi, E., Roudier, E., Rullman, E., Tharmalingam, S., Liu, H.-Y., Gustafsson, T., Haas, T. L. Endothelial FoxO proteins impair insulin sensitivity and restrain muscle angiogenesis in response to a high-fat diet.
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Gorduras na Dieta/efeitos adversos , Proteína Forkhead Box O1/metabolismo , Resistência à Insulina , Músculo Esquelético/irrigação sanguínea , Neovascularização Fisiológica/efeitos dos fármacos , Animais , Células Cultivadas , Gorduras na Dieta/administração & dosagem , Células Endoteliais/efeitos dos fármacos , Proteína Forkhead Box O1/genética , Camundongos , Camundongos Knockout , ObesidadeRESUMO
Capillaries, which are the smallest and most abundant type of blood vessel, form the primary site of gas, nutrient, and waste transfer between the vascular and tissue compartments. Skeletal muscle exhibits the capacity to generate new capillaries (angiogenesis) as an adaptation to exercise training, thus ensuring that the heightened metabolic demand of the active muscle is matched by an improved capacity for distribution of gases, nutrients, and waste products. This review summarizes the current understanding of the regulation of skeletal muscle capillary growth. The multi-step process of angiogenesis is coordinated through the integration of a diverse array of signals associated with hypoxic, metabolic, hemodynamic, and mechanical stresses within the active muscle. The contributions of metabolic and mechanical factors to the modulation of key pro- and anti-angiogenic molecules are discussed within the context of responses to a single aerobic exercise bout and short-term and long-term training. Finally, the paradoxical lack of angiogenesis in peripheral artery disease and diabetes and the implications for disease progression and muscle health are discussed. Future studies that emphasize an integrated analysis of the mechanisms that control skeletal muscle capillary growth will enable development of targeted exercise programs that effectively promote angiogenesis in healthy individuals and in patient populations.
Assuntos
Capilares/crescimento & desenvolvimento , Angiopatias Diabéticas/fisiopatologia , Exercício Físico/fisiologia , Músculo Esquelético/irrigação sanguínea , Neovascularização Fisiológica , Doença Arterial Periférica/fisiopatologia , Adaptação Fisiológica , Proteínas Angiogênicas/sangue , Animais , Distinções e Prêmios , Capilares/metabolismo , Hipóxia Celular , Angiopatias Diabéticas/sangue , Angiopatias Diabéticas/terapia , Humanos , Doença Arterial Periférica/sangue , Doença Arterial Periférica/terapia , Prognóstico , Transdução de SinaisRESUMO
Diabetes is rapidly induced in young male Sprague-Dawley rats following treatment with exogenous corticosterone (CORT) and a high-fat diet (HFD). Regular exercise alleviates insulin insensitivity and improves pancreatic ß-cell function in insulin-resistant/diabetic rodents, but its effect in an animal model of elevated glucocorticoids is unknown. We examined the effect of voluntary exercise (EX) on diabetes development in CORT-HFD-treated male Sprague-Dawley rats (â¼6 wk old). Animals were acclimatized to running wheels for 2 wk, then given a HFD, either wax (placebo) or CORT pellets, and split into 4 groups: placebo-sedentary (SED) or -EX and CORT-SED or -EX. After 2 wk of running combined with treatment, CORT-EX animals had reduced visceral adiposity, and increased skeletal muscle type IIb/x fiber area, oxidative capacity, capillary-to-fiber ratio and insulin sensitivity compared with CORT-SED animals (all P < 0.05). Although CORT-EX animals still had fasting hyperglycemia, these values were significantly improved compared with CORT-SED animals (14.3 ± 1.6 vs. 18.8 ± 0.9 mM). In addition, acute in vivo insulin response to an oral glucose challenge was enhanced â¼2-fold in CORT-EX vs. CORT-SED (P < 0.05) which was further demonstrated ex vivo in isolated islets. We conclude that voluntary wheel running in rats improves, but does not fully normalize, the metabolic profile and skeletal muscle composition of animals administered CORT and HFD.
Assuntos
Comportamento Animal , Glicemia/metabolismo , Corticosterona , Diabetes Mellitus Experimental/prevenção & controle , Dieta Hiperlipídica , Glucocorticoides , Insulina/sangue , Ilhotas Pancreáticas/metabolismo , Esforço Físico , Volição , Adiposidade , Animais , Biomarcadores/sangue , Peso Corporal , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/fisiopatologia , Diabetes Mellitus Experimental/psicologia , Metabolismo Energético , Homeostase , Gordura Intra-Abdominal/metabolismo , Gordura Intra-Abdominal/fisiopatologia , Ilhotas Pancreáticas/fisiopatologia , Masculino , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Atrofia Muscular/induzido quimicamente , Atrofia Muscular/patologia , Atrofia Muscular/prevenção & controle , Ratos Sprague-Dawley , Corrida , Fatores de TempoRESUMO
The physiological process of exercise-induced angiogenesis involves the orchestrated upregulation of angiogenic factors together with repression of angiostatic factors. The Forkhead Box 'O' (FoxO) transcription factors promote an angiostatic environment in pathological contexts. We hypothesized that endothelial FoxO1 and FoxO3a also play an integral role in restricting the angiogenic response to aerobic exercise training. A single exercise bout significantly increased levels of FoxO1 and FoxO3a mRNA (5.5- and 1.7-fold, respectively) and protein (1.7- and 2.2-fold, respectively) within the muscles of mice 2 h post-exercise compared to sedentary. Training abolished the exercise-induced increases in both FoxO1 and FoxO3a mRNA and proteins, and resulted in significantly lower nuclear levels of FoxO1 and FoxO3a protein (0.5- and 0.4-fold, respectively, relative to sedentary). Thrombospondin 1 (THBS1) protein level closely mirrored the expression pattern of FoxO proteins. The 1.7-fold increase in THBS1 protein following acute exercise no longer occurred after 10 days of repeated exercise. Endothelial cell-directed conditional deletion of FoxO1/3a/4 in mice prevented the increase in THBS1 mRNA following a single exercise bout. Mice harbouring the endothelial FoxO deletion also demonstrated a significant 20% increase in capillary to muscle fibre ratio after only 7 days of training while 14 days of training was required to elicit a similar increase in wildtype littermates. Our results demonstrate that the downregulation of FoxO1 and FoxO3a proteins facilitates angiogenesis in response to repeated exercise. In conclusion, FoxO proteins can delay exercise-induced angiogenesis, and thus are critical regulators of the physiological angiogenic response in skeletal muscle.