Mitochondrial oxidative stress corrupts coronary collateral growth by activating adenosine monophosphate activated kinase-alpha signaling.
AMP-Activated Protein Kinases/*metabolism; Animal; Animals; Body Weight/physiology; Cells; collateral circulation; coronary circulation; Coronary Vessels/cytology/*enzymology; Cultured; Disease Models; Endothelial Cells/cytology/*enzymology; Humans; Inbred WKY; Ischemia/metabolism/pathology; mitochondria; Mitochondria/drug effects/*metabolism; Myocardium/enzymology/pathology; Oxidative Stress/*physiology; Rats; reactive oxygen species; Rotenone/pharmacology; Signal Transduction/*physiology; TOR Serine-Threonine Kinases/metabolism; Uncoupling Agents/pharmacology
OBJECTIVE: Our goal was to determine the mechanism by which mitochondrial oxidative stress impairs collateral growth in the heart. APPROACH AND RESULTS: Rats were treated with rotenone (mitochondrial complex I inhibitor that increases reactive oxygen species production) or sham-treated with vehicle and subjected to repetitive ischemia protocol for 10 days to induce coronary collateral growth. In control rats, repetitive ischemia increased flow to the collateral-dependent zone; however, rotenone treatment prevented this increase suggesting that mitochondrial oxidative stress compromises coronary collateral growth. In addition, rotenone also attenuated mitochondrial complex I activity and led to excessive mitochondrial aggregation. To further understand the mechanistic pathway(s) involved, human coronary artery endothelial cells were treated with 50 ng/mL vascular endothelial growth factor, 1 micromol/L rotenone, and rotenone/vascular endothelial growth factor for 48 hours. Vascular endothelial growth factor induced robust tube formation; however, rotenone completely inhibited this effect (P\textless0.05 rotenone versus vascular endothelial growth factor treatment). Inhibition of tube formation by rotenone was also associated with significant increase in mitochondrial superoxide generation. Immunoblot analyses of human coronary artery endothelial cells with rotenone treatment showed significant activation of adenosine monophosphate activated kinase (AMPK)-alpha and inhibition of mammalian target of rapamycin and p70 ribosomal S6 kinase. Activation of AMPK-alpha suggested impairments in energy production, which was reflected by decrease in O2 consumption and bioenergetic reserve capacity of cultured cells. Knockdown of AMPK-alpha (siRNA) also preserved tube formation during rotenone, suggesting the negative effects were mediated by the activation of AMPK-alpha. Conversely, expression of a constitutively active AMPK-alpha blocked tube formation. CONCLUSIONS: We conclude that activation of AMPK-alpha during mitochondrial oxidative stress inhibits mammalian target of rapamycin signaling, which impairs phenotypic switching necessary for the growth of blood vessels.
Pung Yuh Fen; Sam Wai Johnn; Stevanov Kelly; Enrick Molly; Chen Chwen-Lih; Kolz Christopher; Thakker Prashanth; Hardwick James P; Chen Yeong-Renn; Dyck Jason R B; Yin Liya; Chilian William M
Arteriosclerosis, thrombosis, and vascular biology
2013
2013-08
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1161/ATVBAHA.113.301591" target="_blank" rel="noreferrer noopener">10.1161/ATVBAHA.113.301591</a>
Impact of type 1 diabetes on cardiac fibroblast activation: enhanced cell cycle progression and reduced myofibroblast content in diabetic myocardium.
Animals; Blood Glucose/metabolism; Blotting; Body Weight/physiology; Cell Cycle Proteins/biosynthesis; Cell Cycle/*physiology; Cell Differentiation/physiology; Cell Proliferation; Cell Separation; Diabetes Mellitus; Echocardiography; Experimental/pathology; Fibroblasts/*physiology; Male; Microarray Analysis; Myocardium/cytology/*pathology; Myofibroblasts/*physiology; Phenotype; Rats; RNA/biosynthesis/isolation & purification; Signal Transduction/physiology; Sprague-Dawley; Type 1/diagnostic imaging/*pathology; Western
Diabetic patients are prone to developing myocardial fibrosis and suffer from decreased wound healing capabilities. The purpose of this study was to determine whether diabetes alters cardiac fibroblast activity in the myocardium in a 6-wk streptozotocin-induced type 1 diabetic model. In vivo echocardiography indicated significant dilation of the left ventricle (LV) in the diabetic animals, while cardiac function was comparable to that in the normal group. We isolated cardiac fibroblasts from diabetic and control hearts and observed increased proliferation of the diabetic fibroblasts. Microarray analysis using mRNA collected from whole LVs revealed downregulation of known inhibitors of proliferation, p53 and p21, in the diabetic group, consistent with our proliferation data. Western blot analysis confirmed a reduction in p53 protein expression in the diabetic hearts compared with control. We explored the potential signaling underlying the downregulation of these cell cycle mediators and determined that activated Akt, a signal that inhibits p53, was elevated in the diabetic group. Surprisingly, the hearts from the diabetic group contained lower levels of the myofibroblast marker alpha-smooth muscle actin (alpha-SMA) and higher levels of desmin and platelet endothelial cell adhesion molecule (PECAM). The isolated fibroblasts from the diabetic group also contained significantly less alpha-SMA. These data suggest that early-stage diabetic hearts contain highly proliferative fibroblasts, which predisposes the diabetic myocardium to fibrosis, but have fewer myofibroblasts, which may compromise wound healing.
Shamhart Patricia E; Luther Daniel J; Hodson Ben R; Koshy John C; Ohanyan Vahagn; Meszaros J Gary
American journal of physiology. Endocrinology and metabolism
2009
2009-11
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpendo.00327.2009" target="_blank" rel="noreferrer noopener">10.1152/ajpendo.00327.2009</a>
Daily exercise reduces fat, protein and body mass in male but not female rats.
*Body Mass Index; Adipose Tissue/*metabolism; Animals; Body Composition/*physiology; Body Weight/physiology; Energy Metabolism/*physiology; Female; Gonadal Steroid Hormones/physiology; Male; Physical Exertion/*physiology; Proteins/*metabolism; Rats; Sex Characteristics; Sprague-Dawley
This study was designed to compare the estimated energy balance, linear growth (body and bone lengths) and body composition (all components including body mass, total body water, fat, protein and ash) response to daily spontaneous running (DSR) in young male and female rats. We tested the hypothesis that due to gender differences in energy efficiency, DSR would reduce linear growth and body composition more in male rats. Fourteen male and sixteen female weanling Sprague-Dawley rats were randomly assigned to either a sedentary (SED) control (male 7, female 8) or DSR (male 7, female 8) group. The DSR rats were allowed to run spontaneously in running wheels while SED rats remained in standard rat cages for 9 weeks. Body mass, running distance and food intake were measured over the nine week period. Subsequently, chemical analysis was performed to measure carcass content of water, protein, fat and ash. Linear growth was assessed by measures of body and bone lengths. The estimated energy balance of the DSR rats was computed and compared between genders. Estimated energy balance was significantly more negative in females than males due to significantly greater DSR distance. Body and bone lengths were similar among the SED and DSR female and SED and DSR male rats. However, whole body mass, fat mass and protein mass were significantly lower only in DSR males. These results demonstrate that DSR reduced body mass, body fat and protein mass in male rats but not in female rats despite a more negative estimated energy balance in female rats. These findings suggest that females are better protected from an energy deficit due to DSR. Possible mechanisms include gender-specific hormonal responses.
Cortright R N; Chandler M P; Lemon P W; DiCarlo S E
Physiology & behavior
1997
1997-07
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1016/s0031-9384(97)00148-0" target="_blank" rel="noreferrer noopener">10.1016/s0031-9384(97)00148-0</a>
Diabetes reduces growth and body composition more in male than in female rats.
Aging/physiology; Animals; Blood Glucose/metabolism; Body Composition/*physiology; Body Weight/physiology; Diabetes Mellitus; Experimental/*physiopathology; Female; Growth/*physiology; Inbred Lew; Male; Rats; Sex Characteristics
Food restriction and/or starvation has a consistently greater and more permanent effect on physical growth in males than in females. Because diabetes may be viewed as being analogous to starvation, we tested the hypothesis that diabetes would reduce growth more in male than in female rats. Diabetes was induced with streptozotocin (65-125 mg/kg IP) at 3 weeks of age in 7 female and 10 male Lewis rats. Body weight (BW) and blood glucose (bGlc) were measured over the following 8 weeks. Subsequently, animals were assessed for body (ano-nasal; ANL) and bone length (tibia; TBL) and chemically analyzed for body composition. Results were compared to age-matched controls (male = 11; female = 9). A 2-way factorial analysis of covariance (ANCOVA), with body weight as the covariate, was used to test for statistical significance for the effects of gender and diabetes on body composition (fat and protein mass) and linear growth because control males and females had significantly different body weights. There were no significant differences in bGlc between genders. However, males had a greater decrease from controls in BW (-45% vs. -13%), protein (-48% vs. -11%), fat (-89% vs. -65%), TBL (-13% vs. 0%), and ANL (-17% vs. -5%) compared to females. In addition, males had a greater absolute decrease from controls in protein (-40 g vs. -5 g) and fat (-39 g vs. -23 g) mass. These results suggest that male rats are more susceptible than females to the deleterious effects of diabetes on linear growth and body composition.
Cortright R N; Collins H L; Chandler M P; Lemon P W; DiCarlo S E
Physiology & behavior
1996
1996-11
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1016/s0031-9384(96)00222-3" target="_blank" rel="noreferrer noopener">10.1016/s0031-9384(96)00222-3</a>