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Saint C, Gittings W, Bunda J, Giles C, Sacco SM, Vandenboom R, Ward WE, LeBlanc PJ. Maternal folic acid supplementation does not impact skeletal muscle function and metabolism in male and female CD-1 mouse offspring. Appl Physiol Nutr Metab 2024; 49:306-318. [PMID: 37913528 DOI: 10.1139/apnm-2023-0207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Folic acid fortification of all white flour, enriched pasta, and cornmeal products became mandatory in Canada to reduce risk of neural tube defects at birth. Furthermore, Health Canada and the Society of Obstetricians and Gynaecologists of Canada recommend women take daily prenatal folic acid supplements in addition to folic acid fortified foods during pregnancy. However, the influence of maternal folic acid supplementation on offspring development, specifically the highly abundant and metabolically active skeletal muscle, is currently unknown. Thus, the purpose of this study was to determine the effect of supplemental folic acid (four times higher than normal dietary consumption), in utero and throughout suckling on muscle size, function, and metabolism in male and female CD-1 mouse offspring. The major findings were that maternal exposure to supplemental folic acid (i) had no impact on postpartum growth rates or muscle mass in female and male offspring, (ii) had no impact on skeletal muscle contractile kinetics in females and male offspring, and (iii) increased maximal phosphofructokinase activity in extensor digitorum longus of female and male offspring. These findings suggest that exposure to folic acid supplementation in utero and throughout suckling at levels four times higher than recommended had minimal effect on skeletal muscle size, function, and metabolism regardless of sex. Future research is needed explore the underlying biological pathways and mechanisms affected by folic acid supplementation during pregnancy and lactation on offspring skeletal muscle tissue, specifically in humans.
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Affiliation(s)
- Caitlin Saint
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - William Gittings
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Jordan Bunda
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Cameron Giles
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Sandra M Sacco
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Rene Vandenboom
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Wendy E Ward
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
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2
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Baranowski BJ, Mohammad A, Finch MS, Brown A, Dhaliwal R, Marko DM, LeBlanc PJ, McCormick CM, Fajardo VA, MacPherson REK. Exercise training and BDNF injections alter APP processing enzymes and improve cognition. J Appl Physiol (1985) 2023. [PMID: 37262102 DOI: 10.1152/japplphysiol.00114.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 05/25/2023] [Indexed: 06/03/2023] Open
Abstract
Exercise reduces cognitive aging, neurodegeneration, and Alzheimer's disease (AD) risk. Acute exercise reduces the activity of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), the rate limiting enzyme in the production of Aβ. However, mechanisms mediating these effects remain largely unknown. Work has implicated brain-derived neurotrophic factor (BDNF) in the processing of amyloid precursor protein (APP). BDNF is an exercise-induced neurotrophin known for its role in synaptic plasticity, neurite growth, and neuronal survival. Previously, our lab has shown using an ex vivo model that treatment of the prefrontal cortex with BDNF reduced BACE1 activity, highlighting a BDNF to BACE1 link. The purpose of this research was to examine whether BDNF treatments resulted in similar biochemical adaptations to APP processing as exercise training. Male C57BL6/J mice were assigned into one of four groups (n=12/group): 1) control; 2) exercise training (progressive treadmill training 5 days/week); 3) BDNF (0.5 mg/kg body mass subcutaneous injection 5 days/week); or 4) endurance training and BDNF, for an 8-week intervention. Recognition memory was measured with a novel object recognition test. Serum, the prefrontal cortex, and hippocampus were collected. BDNF improved recognition memory to a similar extent as endurance training. BDNF and exercise decreased BACE1 activity and increased ADAM10 activity in the prefrontal cortex, indicating a shift in APP processing. Our novel results indicate that BDNF exerts similar beneficial effects on cognition and APP processing as exercise. Future evidence-based preventative or therapeutic interventions that increase BDNF and reduce BACE1 will be valuable for populations at risk of AD.
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Affiliation(s)
| | - Ahmad Mohammad
- Department of Health Sciences, Brock University, St Catharines, Ontario, Canada
| | - Michael S Finch
- Department of Health Sciences, Brock University, St Catharines, Ontario, Canada
| | - Alex Brown
- Department of Health Sciences, Brock University, St Catharines, Ontario, Canada
| | - Roopan Dhaliwal
- Department of Health Sciences, Brock University, St Catharines, Ontario, Canada
| | - Daniel M Marko
- Department of Health Sciences, Brock University, St Catharines, Ontario, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Brock University, St Catharines, Ontario, Canada
| | - Cheryl M McCormick
- Department of Psychology, Brock University, St Catharines, ON, Canada
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - Val A Fajardo
- Department of Kinesiology, Brock University, St Catharines, ON, Canada
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - Rebecca E K MacPherson
- Department of Health Sciences, Brock University, St Catharines, Ontario, Canada
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
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3
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Elkes M, Andonovski M, Vidal D, Farago M, Modafferi R, Claypool SM, LeBlanc PJ. The Influence of Supplemental Dietary Linoleic Acid on Skeletal Muscle Contractile Function in a Rodent Model of Barth Syndrome. Front Physiol 2021; 12:731961. [PMID: 34489741 PMCID: PMC8416984 DOI: 10.3389/fphys.2021.731961] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/02/2021] [Indexed: 11/13/2022] Open
Abstract
Barth syndrome is a rare and incurable X-linked (male-specific) genetic disease that affects the protein tafazzin (Taz). Taz is an important enzyme responsible for synthesizing biologically relevant cardiolipin (for heart and skeletal muscle, cardiolipin rich in linoleic acid), a critical phospholipid of mitochondrial form and function. Mutations to Taz cause dysfunctional mitochondria, resulting in exercise intolerance due to skeletal muscle weakness. To date, there has been limited research on improving skeletal muscle function, with interventions focused on endurance and resistance exercise. Previous cell culture research has shown therapeutic potential for the addition of exogenous linoleic acid in improving Taz-deficient mitochondrial function but has not been examined in vivo. The purpose of this study was to examine the influence of supplemental dietary linoleic acid on skeletal muscle function in a rodent model of Barth syndrome, the inducible Taz knockdown (TazKD) mouse. One of the main findings was that TazKD soleus demonstrated an impaired contractile phenotype (slower force development and rates of relaxation) in vitro compared to their WT littermates. Interestingly, this impaired contractile phenotype seen in vitro did not translate to altered muscle function in vivo at the whole-body level. Also, supplemental linoleic acid attenuated, to some degree, in vitro impaired contractile phenotype in TazKD soleus, and these findings appear to be partially mediated by improvements in cardiolipin content and resulting mitochondrial supercomplex formation. Future research will further examine alternative mechanisms of dietary supplemental LA on improving skeletal muscle contractile dysfunction in TazKD mice.
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Affiliation(s)
- Mario Elkes
- Faculty of Applied Health Sciences, Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Martin Andonovski
- Faculty of Applied Health Sciences, Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Daislyn Vidal
- Faculty of Applied Health Sciences, Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Madison Farago
- Faculty of Applied Health Sciences, Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Ryan Modafferi
- Faculty of Applied Health Sciences, Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Steven M Claypool
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Paul J LeBlanc
- Faculty of Applied Health Sciences, Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
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4
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Silvera S, Wilkinson JA, LeBlanc PJ. Characterization of neutral sphingomyelinase activity and isoform expression in rodent skeletal muscle mitochondria. Mitochondrion 2021; 59:184-189. [PMID: 34089907 DOI: 10.1016/j.mito.2021.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/04/2021] [Accepted: 06/01/2021] [Indexed: 12/01/2022]
Abstract
Skeletal muscle is composed of fiber types that differ in mitochondrial content, antioxidant capacity, and susceptibility to apoptosis. Ceramides have been linked to oxidative stress-mediated apoptotic intracellular signalling and the enzyme neutral sphingomyelinase (nSMase) is, in part, responsible for generating these ceramides through the hydrolysis of sphingomyelin. Despite the role of ceramides in mediating apoptosis, there is a gap in the literature regarding nSMase in skeletal muscle mitochondria. This study aimed to characterize total nSMase activity and individual isoform expression in isolated subsarcolemmal (SS) mitochondria from soleus, diaphragm, plantaris, and extensor digitorum longus (EDL). Total nSMase activity did not differ between muscle types. nSMase2 content was detectable in all muscles and higher in EDL, soleus, and plantaris compared to diaphragm whereas nSMase3 was undetectable in all muscles. Finally, total nSMase activity positively correlated to nSMase2 protein content in soleus but not the other muscles. These findings suggest that nSMase associated with SS mitochondria may play a role in intracellular signalling processes involving ceramides in skeletal muscle and nSMase2 may be the key isoform, specifically in slow twitch muscle like soleus. Further studies are needed to fully elucidate the specific contribution of nSMase, along with the role of the various isoforms and mitochondrial subpopulation in generating mitochondrial ceramides in skeletal muscle, and its potential effects on mediating apoptosis.
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Affiliation(s)
- Sebastian Silvera
- Center for Bone and Muscle Health, Faculty of Applied Health Science, Brock University, Canada
| | - Jennifer A Wilkinson
- Center for Bone and Muscle Health, Faculty of Applied Health Science, Brock University, Canada
| | - Paul J LeBlanc
- Center for Bone and Muscle Health, Faculty of Applied Health Science, Brock University, Canada.
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5
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Maguire ARR, Crozier RWE, Hunter KD, Claypool SM, Fajardo VA, LeBlanc PJ, MacNeil AJ. Tafazzin Modulates Allergen-Induced Mast Cell Inflammatory Mediator Secretion. Immunohorizons 2021; 5:182-192. [PMID: 33895725 DOI: 10.4049/immunohorizons.2000040] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 03/26/2021] [Indexed: 11/19/2022] Open
Abstract
Allergic inflammatory diseases are a steadily growing health concern. Mast cells, a driving force behind allergic pathologies, modulate metabolic pathways to carry out various functions following IgE-FcεRI-mediated activation. Tafazzin (TAZ) is a cardiolipin transacylase that functions to remodel, and thereby mature, cardiolipin, which is important for efficient energy production through oxidative phosphorylation. In this study, we aimed to evaluate the contribution of TAZ in IgE-mediated mast cell activation. Fetal liver-derived mast cells (FLMCs) were differentiated from mice with a doxycycline (dox)-inducible TAZ short hairpin RNA (shRNA) cassette (TAZ shRNA+/+) and littermate wild-types (WTs). TAZ knockdown in FLMCs following dox treatment was confirmed by Western blotting (99.1% by day 5), whereas flow cytometry confirmed FLMC phenotype (c-kit+ FcεRI+) and retention of receptor expression post-dox. Five-day dox-treated WT and TAZ shRNA+/+ FLMCs were activated via allergen-bound IgE cross-linking of FcεRI under stem cell factor potentiation. With dox, and in response to allergen, TAZ shRNA+/+ FLMCs displayed a 25% reduction in oxygen consumption and a significant 31% reduction in mast cell degranulation compared with dox-treated WT FLMCs. Secretion of TNF, CCL1, and CCL2 were significantly reduced, with CCL9 also impaired. Notably, gene expression was not impaired for any inflammatory mediator measured. Functionally, this suggests that TAZ is a contributor to mast cell degranulation and inflammatory mediator secretion. Given unimpacted induced gene expression for mediators measured, we propose that TAZ reduction impairs mast cell exocytosis mechanisms. We thus identify a potential new contributor to immunometabolism that enhances our understanding of mast cell signaling metabolic pathway interactions during allergic inflammation.
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Affiliation(s)
- Aindriu R R Maguire
- Department of Health Sciences, Cairns Family Health and Bioscience Research Complex, Brock University, St. Catharines, Niagara Region, St. Catharines, Ontario, Canada
| | - Robert W E Crozier
- Department of Health Sciences, Cairns Family Health and Bioscience Research Complex, Brock University, St. Catharines, Niagara Region, St. Catharines, Ontario, Canada
| | - Katie D Hunter
- Department of Health Sciences, Cairns Family Health and Bioscience Research Complex, Brock University, St. Catharines, Niagara Region, St. Catharines, Ontario, Canada
| | - Steven M Claypool
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD; and
| | - Val A Fajardo
- Department of Kinesiology, Cairns Family Health and Bioscience Research Complex, Brock University, Niagara Region, Ontario, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Cairns Family Health and Bioscience Research Complex, Brock University, St. Catharines, Niagara Region, St. Catharines, Ontario, Canada
| | - Adam J MacNeil
- Department of Health Sciences, Cairns Family Health and Bioscience Research Complex, Brock University, St. Catharines, Niagara Region, St. Catharines, Ontario, Canada;
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Wilkinson JA, Silvera S, LeBlanc PJ. The effect of cardiolipin side chain composition on cytochrome c protein conformation and peroxidase activity. Physiol Rep 2021; 9:e14772. [PMID: 33667034 PMCID: PMC7934914 DOI: 10.14814/phy2.14772] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 01/21/2021] [Accepted: 02/01/2021] [Indexed: 12/26/2022] Open
Abstract
Skeletal muscle, a highly active tissue, makes up 40% of the total body weight. This tissue relies on mitochondria for ATP production, calcium homeostasis, and programed cell death. Mitochondrial phospholipid composition, namely, cardiolipin (CL), influences the functional efficiency of mitochondrial proteins, specifically cytochrome c. The interaction of CL with cytochrome c in the presence of free radicals induces structural and functional changes promoting peroxidase activity and cytochrome c release, a key event in the initiation of apoptosis. The CL acyl chain degree of saturation has been implicated in the cytochrome c to cytochrome c peroxidase transition in liposomal models. However, mitochondrial membranes are composed of differing CL acyl chain composition. Currently, it is unclear how differing CL acyl chain composition utilizing liposomes will influence the cytochrome c form and function as a peroxidase. Thus, this study examined the role of CL acyl chain saturation within liposomes broadly reflecting the relative CL composition of mitochondrial membranes from healthy and dystrophic mouse muscle on cytochrome c conformation and function. Despite no differences in protein conformation or function between healthy and dystrophic liposomes, cytochrome c's affinity to CL increased with greater unsaturation. These findings suggest that increasing CL acyl chain saturation, as implicated in muscle wasting diseases, may not influence cytochrome c transformation and function as a peroxidase but may alter its interaction with CL, potentially impacting further downstream effects.
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Affiliation(s)
- Jennifer A Wilkinson
- Center for Bone and Muscle Health, Faculty of Applied Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario, L2S 3A1, Canada
| | - Sebastian Silvera
- Center for Bone and Muscle Health, Faculty of Applied Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario, L2S 3A1, Canada
| | - Paul J LeBlanc
- Center for Bone and Muscle Health, Faculty of Applied Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario, L2S 3A1, Canada
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7
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Maguire ARR, Crozier RWE, LeBlanc PJ, MacNeil AJ. Tafazzin contributes to IgE‐mediated mast cell degranulation and cytokine secretion. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.05544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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8
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Townsend LK, Gandhi S, Shamshoum H, Trottier SK, Mutch DM, Reimer RA, Shearer J, LeBlanc PJ, Wright DC. Exercise and Dairy Protein have Distinct Effects on Indices of Liver and Systemic Lipid Metabolism. Obesity (Silver Spring) 2020; 28:97-105. [PMID: 31729829 DOI: 10.1002/oby.22621] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/23/2019] [Indexed: 12/17/2022]
Abstract
OBJECTIVE This study aimed to explore the individual and combined effects of skim milk powder (SMP) and exercise on indices of systemic and liver lipid metabolism in male obese rats. METHODS Rats were fed a high-fat (~ 40% kcal from fat), high-sugar diet for 8 weeks. At 12 weeks of age, rats were assigned to one of four weight-matched, isocaloric, high-fat, high-sugar groups for 6 weeks: (1) casein-sedentary, (2) casein-exercise, (3) SMP-sedentary, and (4) SMP-exercise. Nonfat SMP or casein was the sole protein source in the dairy and control casein diets, respectively. Exercise training occurred 5 d/wk for 60 minutes on a motorized treadmill. Whole-body metabolism was assessed by a Comprehensive Lab Animal Monitoring System. Lipidomics, Western blot, and polymerase chain reaction were used to assess markers of hepatic lipid metabolism. RESULTS Exercise, but not SMP, altered the fatty acid composition of liver triglycerides, reduced indices of lipogenesis, and increased expression of genes linked to oxidative metabolism, in conjunction with increases in whole-body fat oxidation. SMP and exercise reduced plasma triglycerides in an additive manner. CONCLUSIONS These findings provide evidence that SMP and exercise exert distinct effects on whole-body and hepatic carbohydrate and lipid metabolism and that they could work in a synergistic manner to reduce serum triglyceride concentrations.
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Affiliation(s)
- Logan K Townsend
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Shivam Gandhi
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Hesham Shamshoum
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Sarah K Trottier
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - David M Mutch
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Raylene A Reimer
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jane Shearer
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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9
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Hayward GC, LeBlanc PJ, Emter CA, Nyarko JNK, Mousseau DD, MacPherson REK, Olver TD. Female Sex Hormones and Cardiac Pressure Overload Independently Contribute to the Cardiogenic Dementia Profile in Yucatan Miniature Swine. Front Cardiovasc Med 2019; 6:129. [PMID: 31552273 PMCID: PMC6746895 DOI: 10.3389/fcvm.2019.00129] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 08/19/2019] [Indexed: 01/29/2023] Open
Abstract
Post-menopausal women with heart failure (HF) frequently exhibit cardiogenic dementia. Using a pre-clinical swine model of post-menopausal HF, we recently demonstrated that experimental menopause (ovariectomy; OVX) and HF (6-month cardiac pressure overload/aortic banding; AB) independently altered cerebral vasomotor control and together impaired cognitive function. The purpose of this study was to examine the prefrontal cortex and hippocampus tissues from these animals to assess whether OVX and HF are associated with neurologic alterations that may contribute to cardiogenic dementia. We hypothesized that OVX and HF would independently alter neuronal cell signaling in swine with post-menopausal cardiogenic dementia. Immunoblot analyses revealed OVX was associated with reduced estrogen receptor-α in both brain regions and HF tended to exacerbate OVX-induced deficits in the hippocampus. Further, OVX was associated with a reduction in the ratio of phosphorylated:total Akt and ERK in the hippocampus as well as decreased total Akt and synaptophysin in the prefrontal cortex. In contrast, HF was associated with a trend toward reduced phosphorylated:total ERK in the prefrontal cortex. In addition, HF was associated with decreased β-amyloid (1-38) in the prefrontal cortex and increased β-amyloid (1-38) in the hippocampus. Regional brain lipid analysis revealed OVX tended to increase total, saturated, and monounsaturated fatty acid content in the prefrontal cortex, with the greatest magnitude of change occurring in the AB-OVX group. The data from this study suggest that OVX and HF are independently associated with regional-specific neurologic changes in the brain that contribute to the cardiogenic dementia profile in this model. This pre-clinical swine model may be a useful tool for better understanding post-menopausal cardiogenic dementia pathology and developing novel therapies.
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Affiliation(s)
- Grant C. Hayward
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - Paul J. LeBlanc
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Craig A. Emter
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States
| | - Jennifer N. K. Nyarko
- Department of Psychiatry, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Darrell D. Mousseau
- Department of Psychiatry, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Rebecca E. K. MacPherson
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - T. Dylan Olver
- Department of Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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10
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Fajardo VA, Watson CJF, Bott KN, Moradi F, Maddalena LA, Bellissimo CA, Turner KD, Peters SJ, LeBlanc PJ, MacNeil AJ, Stuart JA, Tupling AR. Neurogranin is expressed in mammalian skeletal muscle and inhibits calcineurin signaling and myoblast fusion. Am J Physiol Cell Physiol 2019; 317:C1025-C1033. [PMID: 31433693 DOI: 10.1152/ajpcell.00345.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Calcineurin is a Ca2+/calmodulin (CaM)-dependent phosphatase that plays a critical role in promoting the slow fiber phenotype and myoblast fusion in skeletal muscle, thereby making calcineurin an attractive cellular target for enhancing fatigue resistance, muscle metabolism, and muscle repair. Neurogranin (Ng) is a CaM-binding protein thought to be expressed solely in brain and neurons, where it inhibits calcineurin signaling by sequestering CaM, thus lowering its cellular availability. Here, we demonstrate for the first time the expression of Ng protein and mRNA in mammalian skeletal muscle. Both protein and mRNA levels are greater in slow-oxidative compared with fast-glycolytic muscles. Coimmunoprecipitation of CaM with Ng in homogenates of C2C12 myotubes, mouse soleus, and human vastus lateralis suggests that these proteins physically interact. To determine whether Ng inhibits calcineurin signaling in muscle, we used Ng siRNA with C2C12 myotubes to reduce Ng protein levels by 60%. As a result of reduced Ng expression, C2C12 myotubes had enhanced CaM-calcineurin binding and calcineurin signaling as indicated by reduced phosphorylation of nuclear factor of activated T cells and increased utrophin mRNA. In addition, calcineurin signaling affects the expression of myogenin and stabilin-2, which are involved in myogenic differentiation and myoblast fusion, respectively. Here, we found that both myogenin and stabilin-2 were significantly elevated by Ng siRNA in C2C12 cells, concomitantly with an increased fusion index. Taken together, these results demonstrate the expression of Ng in mammalian skeletal muscle where it appears to be a novel regulator of calcineurin signaling.
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Affiliation(s)
- Val A Fajardo
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada
| | - Colton J F Watson
- Department of Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Kirsten N Bott
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Fereshteh Moradi
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Lucas A Maddalena
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
| | | | - Kelli D Turner
- Department of Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Sandra J Peters
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Brock University, St. Catharines, Ontario, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada
| | - Adam J MacNeil
- Department of Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Jeffrey A Stuart
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
| | - A Russell Tupling
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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11
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Townsend LK, Medak KD, Peppler WT, Meers GM, Rector RS, LeBlanc PJ, Wright DC. High-saturated-fat diet-induced obesity causes hepatic interleukin-6 resistance via endoplasmic reticulum stress. J Lipid Res 2019; 60:1236-1249. [PMID: 31085628 DOI: 10.1194/jlr.m092510] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 04/23/2019] [Indexed: 12/14/2022] Open
Abstract
The relationship between liver interleukin-6 (IL-6) resistance following high-fat diet (HFD)-induced obesity and glucose intolerance is unclear. The purpose of this study was to assess the temporal development of hepatic IL-6 resistance and the role of endoplasmic reticulum (ER) stress in this process. We hypothesized that HFD would rapidly induce hepatic IL-6 resistance through a mechanism involving ER stress. Male C57BL/6N mice consumed chow or a HFD (60%) derived from lard (saturated) or olive oil (monounsaturated) for 4 days or 7 weeks before being injected intraperitoneally with IL-6 (6 ng·kg-1). Glucose, insulin, and pyruvate tolerance tests were used as proxies for systemic glucose metabolism and hepatic glucose production, respectively. Primary mouse hepatocytes were incubated with palmitate (saturated) and oleate (unsaturated) overnight, then treated with 20 ng/ml IL-6. ER stress was induced via tunicamycin or prevented by sodium phenylbutyrate (PBA). Seven weeks of a saturated, but not monounsaturated, HFD reduced hepatic IL-6 signaling in conjunction with hepatic ER stress. Palmitate directly impaired IL-6 signaling in hepatocytes along with inducing ER stress. Pharmacologically induced ER stress caused hepatic IL-6 resistance, whereas PBA reversed HFD-induced IL-6 resistance. Chronic HFD-induced obesity is associated with hepatic IL-6 resistance due to saturated FA-induced ER stress.
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Affiliation(s)
- Logan K Townsend
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Kyle D Medak
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Willem T Peppler
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Grace M Meers
- Division of Gastroenterology and Hepatology, School of Medicine University of Missouri, Columbia, MO.,Research Service, Harry S Truman Memorial VA Hospital, Columbia, MO
| | - R Scott Rector
- Nutrition and Exercise Physiology University of Guelph, Guelph, ON, Canada.,Division of Gastroenterology and Hepatology, School of Medicine University of Missouri, Columbia, MO.,Research Service, Harry S Truman Memorial VA Hospital, Columbia, MO
| | - Paul J LeBlanc
- Department of Health Sciences Brock University, St. Catharines, ON, Canada
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
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12
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Miotto PM, LeBlanc PJ, Holloway GP. High-Fat Diet Causes Mitochondrial Dysfunction as a Result of Impaired ADP Sensitivity. Diabetes 2018; 67:2199-2205. [PMID: 29980534 DOI: 10.2337/db18-0417] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 06/26/2018] [Indexed: 11/13/2022]
Abstract
Although molecular approaches altering mitochondrial content have implied a direct relationship between mitochondrial bioenergetics and insulin sensitivity, paradoxically, consumption of a high-fat (HF) diet increases mitochondrial content while inducing insulin resistance. We hypothesized that despite the induction of mitochondrial biogenesis, consumption of an HF diet would impair mitochondrial ADP sensitivity in skeletal muscle of mice and therefore manifest in mitochondrial dysfunction in the presence of ADP concentrations indicative of skeletal muscle biology. We found that HF consumption increased mitochondrial protein expression; however, absolute mitochondrial respiration and ADP sensitivity were impaired across a range of biologically relevant ADP concentrations. In addition, HF consumption attenuated the ability of ADP to suppress mitochondrial H2O2 emission, further suggesting impairments in ADP sensitivity. The abundance of ADP transport proteins were not altered, but the sensitivity to carboxyatractyloside-mediated inhibition was attenuated after HF consumption, implicating alterations in adenine nucleotide translocase (ANT) ADP sensitivity in these observations. Moreover, palmitoyl-CoA is known to inhibit ANT, and modeling intramuscular palmitoyl-CoA concentrations that occur after HF consumption exacerbated the deficiency in ADP sensitivity. Altogether, these data suggest that an HF diet induces mitochondrial dysfunction secondary to an intrinsic impairment in mitochondrial ADP sensitivity that is magnified by palmitoyl-CoA.
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Affiliation(s)
- Paula M Miotto
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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13
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Fajardo VA, Fajardo VA, LeBlanc PJ, MacPherson REK. Examining the Relationship between Trace Lithium in Drinking Water and the Rising Rates of Age-Adjusted Alzheimer's Disease Mortality in Texas. J Alzheimers Dis 2018; 61:425-434. [PMID: 29103043 PMCID: PMC7592673 DOI: 10.3233/jad-170744] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Background: Alzheimer’s disease (AD) mortality rates have steadily increased over time. Lithium, the current gold standard treatment for bipolar disorder, can exert neuroprotective effects against AD. Objective: We examined the relationship between trace levels of lithium in drinking water and changes in AD mortality across several Texas counties. Methods: 6,180 water samples from public wells since 2007 were obtained and averaged for 234 of 254 Texas counties. Changes in AD mortality rates were calculated by subtracting aggregated age-adjusted mortality rates obtained between 2000–2006 from those obtained between 2009–2015. Using aggregated rates maximized the number of counties with reliable mortality data. Correlational analyses between average lithium concentrations and changes in AD mortality were performed while also adjusting for gender, race, education, rural living, air pollution, physical inactivity, obesity, and type 2 diabetes. Results: Age-adjusted AD mortality rate was significantly increased over time (+27%, p < 0.001). Changes in AD mortality were negatively correlated with trace lithium levels (p = 0.01, r = –0.20), and statistical significance was maintained after controlling for most risk factors except for physical inactivity, obesity, and type 2 diabetes. Furthermore, the prevalence of obesity and type 2 diabetes positively correlated with changes in AD mortality (p = 0.01 and 0.03, respectively), but also negatively correlated with trace lithium in drinking water (p = 0.05 and <0.0001, respectively). Conclusion: Trace lithium in water is negatively linked with changes in AD mortality, as well as obesity and type 2 diabetes, which are important risk factors for AD.
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Affiliation(s)
- Val Andrew Fajardo
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Val Andrei Fajardo
- Department of Actuarial Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Rebecca E K MacPherson
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada.,Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
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14
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Sacco SM, Saint C, LeBlanc PJ, Ward WE. Nutritional Programming of Bone Structure in Male Offspring by Maternal Consumption of Citrus Flavanones. Calcif Tissue Int 2018; 102:671-682. [PMID: 29151126 PMCID: PMC5956010 DOI: 10.1007/s00223-017-0366-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/11/2017] [Indexed: 11/27/2022]
Abstract
Maternal exposure to hesperidin (HSP) and naringin (NAR) during pregnancy and lactation transiently compromised bone mineral density (BMD) and bone structure at the proximal tibia in female CD-1 offspring. We examined whether maternal consumption of HSP + NAR during pregnancy and lactation compromises BMD, bone structure, and bone strength in male CD-1 offspring. Male CD-1 offspring, from mothers fed a control diet (CON, n = 10) or a 0.5% HSP + 0.25% NAR diet (HSP + NAR, n = 8) for 5 weeks before mating and throughout pregnancy and lactation, were weaned and fed CON until 6 months of age. In vivo micro-computed tomography (µCT) measured tibia BMD and structure at 2, 4, and 6 months of age. Ex vivo µCT measured femur and lumbar vertebrae (LV) structure at age 6 months. Ex vivo BMD (femur, LV) and biomechanical strength (femur and tibia midpoint, femur neck) were assessed at age 6 months by dual energy x-ray absorptiometry and strength testing, respectively. At all ages, HSP + NAR offspring had greater (p < 0.05) proximal tibia cortical structure compared to CON offspring. At age 4 months, proximal tibia trabecular structure was greater (p < 0.05) than CON offspring. At age 6 months, femur neck and LV trabecular structure were greater (p < 0.05) than CON offspring. Our results demonstrate that unlike our previous study of female offspring, maternal consumption of HSP + NAR resulted in greater bone structure at the proximal tibia in male CD-1 offspring that persisted to 6 months of age. Thus, maternal programming of offspring BMD and bone structure from consumption of HSP + NAR occurred as a sex-specific response.
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Affiliation(s)
- Sandra M Sacco
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, L2S 3A1, Canada
| | - Caitlin Saint
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, L2S 3A1, Canada
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada
| | - Paul J LeBlanc
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, L2S 3A1, Canada
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada
| | - Wendy E Ward
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada.
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, L2S 3A1, Canada.
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada.
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15
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Bott KN, Watson CJ, Leveille CF, MacNeil AJ, Peters SJ, LeBlanc PJ, Fajardo VA. Soleus and gastrocnemius tenotomy causes fiber type specific muscle atrophy in mouse tibialis anterior. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.856.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kirsten N. Bott
- KinesiologyBrock UniversitySt. CatharinesONCanada
- Centre for Bone and Muscle HealthSt. CatharinesONCanada
| | - Colton J.F. Watson
- Health SciencesBrock UniversitySt. CatharinesONCanada
- Centre for Bone and Muscle HealthSt. CatharinesONCanada
| | - Cameron F. Leveille
- Health SciencesBrock UniversitySt. CatharinesONCanada
- Centre for Bone and Muscle HealthSt. CatharinesONCanada
| | - Adam J. MacNeil
- Health SciencesBrock UniversitySt. CatharinesONCanada
- Centre for Bone and Muscle HealthSt. CatharinesONCanada
| | - Sandra J. Peters
- KinesiologyBrock UniversitySt. CatharinesONCanada
- Centre for Bone and Muscle HealthSt. CatharinesONCanada
| | - Paul J. LeBlanc
- Health SciencesBrock UniversitySt. CatharinesONCanada
- Centre for Bone and Muscle HealthSt. CatharinesONCanada
| | - Val Andrew Fajardo
- Health SciencesBrock UniversitySt. CatharinesONCanada
- Centre for Bone and Muscle HealthSt. CatharinesONCanada
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16
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Fajardo VA, LeBlanc PJ, Fajardo VA. Trace lithium in Texas tap water is negatively associated with all-cause mortality and premature death. Appl Physiol Nutr Metab 2018; 43:412-414. [DOI: 10.1139/apnm-2017-0653] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lithium in tap water was previously found to have life-extending effects across 18 Japanese municipalities. Using a larger dataset with several Texas counties, our study shows that lithium concentrations in tap water are negatively associated with all-cause mortality (r = −0.18, p = 0.006, 232 counties) and years of potential life lost (r = −0.22, p = 0.001, 214 counties). Thus, our present findings extend and reinforce lithium’s purported life-prolonging effect in humans.
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Affiliation(s)
- Val Andrew Fajardo
- Department of Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Paul J. LeBlanc
- Department of Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Val Andrei Fajardo
- Department of Actuarial Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
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17
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Fajardo VA, Mikhaeil JS, Leveille CF, Tupling AR, LeBlanc PJ. Elevated whole muscle phosphatidylcholine: phosphatidylethanolamine ratio coincides with reduced SERCA activity in murine overloaded plantaris muscles. Lipids Health Dis 2018. [PMID: 29534725 PMCID: PMC5851149 DOI: 10.1186/s12944-018-0687-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND An increase in phosphatidylcholine:phosphatidylethanolamine (PC:PE) and a decrease in fatty acyl chain length, monounsaturated:polyunsaturated (MUFA:PUFA) fatty acyl ratio reduces SERCA activity in liposomes and in mouse models of obesity and muscular dystrophy. We have previously shown that maximal SERCA activity is significantly reduced in mechanically overloaded (OVL) plantaris, however, whether changes in PC:PE ratio or fatty acyl composition may contribute to the alterations in maximal SERCA activity remain unknown. Here, we tested the hypotheses that in OVL plantaris 1) PC:PE ratio would negatively correlate with maximal SERCA activity and 2) PC fatty acyl chain length (ACL) and/or MUFA:PUFA ratio would positively correlate with maximal SERCA activity. METHODS To overload plantaris in mice, we transected the soleus and gastrocnemius tendons from one leg, while the contralateral leg underwent a sham surgery. After two weeks, plantaris muscles were extracted, homogenized and processed for SERCA activity and lipid analyses. Specifically, we performed HPTLC densitometry to examine changes in PC, PE, and the ratio of PC:PE. We also performed gas chromatography to assess any potential changes to fatty acyl composition. RESULTS SERCA activity was significantly reduced in OVL plantaris compared with sham. Coinciding with this, we found a significant increase in PC but not PE in OVL plantaris. In turn, there was an increase in PC:PE but did not reach significance (p = 0.09). However, we found a significant negative correlation between PC:PE and maximal SERCA activity. Fatty acyl composition of PE remained similar between OLV and sham and PC demonstrated higher percent mole fraction of 17:1, 18:1, and ACL compared to sham. In addition, PC ACL, % MUFA, % PUFA, or MUFA:PUFA did not significantly correlate with maximal SERCA activity. CONCLUSIONS Our results indicate that the phospholipid headgroup PC:PE negatively correlated and could potentially contribute to reductions in SERCA activity seen in functionally overloaded plantaris. In contrast, fatty acyl chain (ACL, % MUFA, % PUFA, MUFA:PUFA) did not correlate with maximal SERCA activity. Future studies will determine whether altering PC:PE with genetic and dietary interventions can influence SERCA activity and ultimately change the physiological outcome in response to muscle overloading.
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Affiliation(s)
- Val A Fajardo
- Department of Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada.,Centre for Bone and Muscle Health, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
| | - John S Mikhaeil
- Department of Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada.,Centre for Bone and Muscle Health, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Cameron F Leveille
- Department of Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada.,Centre for Bone and Muscle Health, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
| | - A Russell Tupling
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada. .,Centre for Bone and Muscle Health, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.
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18
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Olver TD, Grunewald ZI, Jurrissen TJ, MacPherson REK, LeBlanc PJ, Schnurbusch TR, Czajkowski AM, Laughlin MH, Rector RS, Bender SB, Walters EM, Emter CA, Padilla J. Microvascular insulin resistance in skeletal muscle and brain occurs early in the development of juvenile obesity in pigs. Am J Physiol Regul Integr Comp Physiol 2017; 314:R252-R264. [PMID: 29141949 DOI: 10.1152/ajpregu.00213.2017] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Impaired microvascular insulin signaling may develop before overt indices of microvascular endothelial dysfunction and represent an early pathological feature of adolescent obesity. Using a translational porcine model of juvenile obesity, we tested the hypotheses that in the early stages of obesity development, impaired insulin signaling manifests in skeletal muscle (triceps), brain (prefrontal cortex), and corresponding vasculatures, and that depressed insulin-induced vasodilation is reversible with acute inhibition of protein kinase Cβ (PKCβ). Juvenile Ossabaw miniature swine (3.5 mo of age) were divided into two groups: lean control ( n = 6) and obese ( n = 6). Obesity was induced by feeding the animals a high-fat/high-fructose corn syrup/high-cholesterol diet for 10 wk. Juvenile obesity was characterized by excess body mass, hyperglycemia, physical inactivity (accelerometer), and marked lipid accumulation in the skeletal muscle, with no evidence of overt atherosclerotic lesions in athero-prone regions, such as the abdominal aorta. Endothelium-dependent (bradykinin) and -independent (sodium nitroprusside) vasomotor responses in the brachial and carotid arteries (wire myography), as well as in the skeletal muscle resistance and 2A pial arterioles (pressure myography) were unaltered, but insulin-induced microvascular vasodilation was impaired in the obese group. Blunted insulin-stimulated vasodilation, which was reversed with acute PKCβ inhibition (LY333-531), occurred alongside decreased tissue perfusion, as well as reduced insulin-stimulated Akt signaling in the prefrontal cortex, but not the triceps. In the early stages of juvenile obesity development, the microvasculature and prefrontal cortex exhibit impaired insulin signaling. Such adaptations may underscore vascular and neurological derangements associated with juvenile obesity.
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Affiliation(s)
- T Dylan Olver
- Department of Biomedical Sciences, University of Missouri , Columbia, Missouri
| | - Zachary I Grunewald
- Department of Nutrition and Exercise Physiology, University of Missouri , Columbia, Missouri
| | - Thomas J Jurrissen
- Department of Nutrition and Exercise Physiology, University of Missouri , Columbia, Missouri
| | | | - Paul J LeBlanc
- Department of Health Sciences, Brock University , St. Catharines, Ontario , Canada
| | - Teagan R Schnurbusch
- National Swine Resource and Research Center University of Missouri , Columbia, Missouri
| | - Alana M Czajkowski
- National Swine Resource and Research Center University of Missouri , Columbia, Missouri
| | - M Harold Laughlin
- Department of Biomedical Sciences, University of Missouri , Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri , Columbia, Missouri
| | - R Scott Rector
- Department of Nutrition and Exercise Physiology, University of Missouri , Columbia, Missouri.,Research Service, Harry S. Truman Memorial Veterans Affairs Hospital , Columbia, Missouri.,Department of Medicine, Division of Gastroenterology and Hepatology, University of Missouri , Columbia, Missouri
| | - Shawn B Bender
- Department of Biomedical Sciences, University of Missouri , Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri , Columbia, Missouri.,Research Service, Harry S. Truman Memorial Veterans Affairs Hospital , Columbia, Missouri
| | - Eric M Walters
- National Swine Resource and Research Center University of Missouri , Columbia, Missouri
| | - Craig A Emter
- Department of Biomedical Sciences, University of Missouri , Columbia, Missouri
| | - Jaume Padilla
- Department of Nutrition and Exercise Physiology, University of Missouri , Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri , Columbia, Missouri.,Department of Child Health, University of Missouri , Columbia, Missouri
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19
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Trottier SK, MacPherson REK, Knuth CM, Townsend LK, Peppler WT, Mikhaeil JS, Leveille CF, LeBlanc PJ, Shearer J, Reimer RA, Wright DC. Dairy Attenuates Weight Gain to a Similar Extent as Exercise in Rats Fed a High-Fat, High-Sugar Diet. Obesity (Silver Spring) 2017; 25:1707-1715. [PMID: 28782917 DOI: 10.1002/oby.21941] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/21/2017] [Accepted: 06/22/2017] [Indexed: 01/02/2023]
Abstract
OBJECTIVE To compare the individual and combined effects of dairy and endurance exercise training in reducing weight gain and adiposity in a rodent model of diet-induced obesity. METHODS An 8-week feeding intervention of a high-fat, high-sugar diet was used to induce obesity in male Sprague-Dawley rats. Rats were then assigned to one of four groups for 6 weeks: (1) casein sedentary (casein-S), (2) casein exercise (casein-E), (3) dairy sedentary (dairy-S), and (4) dairy exercise (dairy-E). Rats were exercise trained by treadmill running 5 d/wk. RESULTS Dairy-E prevented weight gain to a greater extent than either dairy or exercise alone. Adipose tissue and liver mass were reduced to a similar extent in dairy-S, casein-E, and dairy-E groups. Differences in weight gain were not explained by food intake or total energy expenditure. The total amount of lipid excreted was greater in the dairy-S compared to casein-S and dairy-E groups. CONCLUSIONS This study provides evidence that dairy limits weight gain to a similar extent as exercise training and the combined effects are greater than either intervention alone. While exercise training reduces weight gain through increases in energy expenditure, dairy appears to increase lipid excretion in the feces.
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Affiliation(s)
- Sarah K Trottier
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Rebecca E K MacPherson
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Carly M Knuth
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Logan K Townsend
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Willem T Peppler
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - John S Mikhaeil
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Cam F Leveille
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Jane Shearer
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Raylene A Reimer
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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20
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Mikhaeil JS, Sacco SM, Saint C, Gittings W, Bunda J, Giles CR, Fajardo VA, Vandenboom R, Ward WE, LeBlanc PJ. Influence of longitudinal radiation exposure from microcomputed tomography scanning on skeletal muscle function and metabolic activity in female CD-1 mice. Physiol Rep 2017; 5:5/13/e13338. [PMID: 28676556 PMCID: PMC5506525 DOI: 10.14814/phy2.13338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 05/29/2017] [Accepted: 06/05/2017] [Indexed: 01/15/2023] Open
Abstract
Microcomputed tomography (μCT) is an imaging technology to assess bone microarchitecture, a determinant of bone strength. When measured in vivo, μCT exposes the skeletal site of interest to a dose of radiation, in addition to nearby skeletal muscles as well. Therefore, the aim of this study was to determine the effects of repeated radiation exposure from in vivo μCT on muscle health – specifically, muscle morphometrics, contractile function, and enzyme activity. This study exposed the right hind limb of female mice to either a low (26 cGy) or moderate (46 cGy) dose, at 2, 4, and 6 months of age, while the left hind limb of the same animal was exposed to a single dose at 6 months to serve as a nonirradiated control. Muscle weight, cross‐sectional area, isometric contractile function, and representative maximal enzyme activities of amino acid, fatty acid, glucose, and oxidative metabolism in extensor digitorum longus (EDL) and soleus were assessed. Low‐dose radiation had no effect. In contrast, moderate‐dose radiation resulted in a 5% increase in time‐to‐peak tension and 16% increase in half‐relaxation time of isometric twitches in EDL, although these changes were not seen when normalized to force. Moderate‐dose radiation also resulted in an ~33% decrease in citrate synthase activity in soleus but not EDL, with no changes to the other enzymes measured. Thus, three low doses of radiation over 6 months had no effect on contractile function or metabolic enzyme activity in soleus and EDL of female mice. In contrast, three moderate doses of radiation over 6 months induced some effects on metabolic enzyme activity in soleus but not EDL. Future studies that wish to investigate muscle tissue that is adjacent to scanned bone should take radiation exposure dose into consideration.
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Affiliation(s)
- John S Mikhaeil
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Sandra M Sacco
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Caitlin Saint
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - William Gittings
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Jordan Bunda
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Cameron R Giles
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Val A Fajardo
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Rene Vandenboom
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Wendy E Ward
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Paul J LeBlanc
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada .,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
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21
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Bott KN, Gittings W, Fajardo VA, Baranowski BJ, Vandenboom R, LeBlanc PJ, Ward WE, Peters SJ. Musculoskeletal structure and function in response to the combined effect of an obesogenic diet and age in male C57BL/6J mice. Mol Nutr Food Res 2017; 61. [PMID: 28556515 DOI: 10.1002/mnfr.201700137] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/16/2017] [Accepted: 05/18/2017] [Indexed: 12/27/2022]
Abstract
SCOPE The effects of a long-term high fat and sucrose diet (HFS) superimposed with aging on bone and muscle structure and/or function. METHODS AND RESULTS Male C57BL/6J mice (20 weeks of age) were randomized to 1 of 3 groups: baseline (BSL, n = 12), or assigned to a control (AGE, n = 12) or HFS (HFS-AGE, n = 11) diet for 13 weeks. Trabecular bone structure, volumetric bone mineral density (vBMD), and body composition, were measured longitudinally at 20, 24, and 32 weeks of age. In vitro contractile measures were performed on isolated soleus and extensor digitorum longus (EDL) muscles for each group. Both AGE and HFS-AGE had similar declines in trabecular bone structure, while HFS-AGE resulted in increased soleus cross-sectional area (CSA) compared to AGE, but this did not translate to greater twitch or tetanic peak force. The ratio of outcomes of bone to muscle declined in both AGE and HFS-AGE compared to BSL as a result of greater declines in trabecular bone structure than muscle function. CONCLUSION Consumption of a 13-week HFS diet at 20 weeks of age did not exacerbate age-related declines in bone or muscle, but these tissues do not decline in a coordinate manner with greater declines in bone than muscle.
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Affiliation(s)
- Kirsten N Bott
- Department of Kinesiology & Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - William Gittings
- Department of Kinesiology & Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Val Andrew Fajardo
- Department of Health Sciences & Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Bradley J Baranowski
- Department of Kinesiology & Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Rene Vandenboom
- Department of Kinesiology & Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Paul J LeBlanc
- Department of Health Sciences & Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Wendy E Ward
- Department of Kinesiology & Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada.,Department of Health Sciences & Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Sandra J Peters
- Department of Kinesiology & Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
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22
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Longo AB, Sullivan PJ, Peters SJ, LeBlanc PJ, Wohl GR, Ward WE. Lifelong intake of flaxseed or menhaden oil to provide varying n-6 to n-3 PUFA ratios modulate bone microarchitecture during growth, but not after OVX in Sprague-Dawley rats. Mol Nutr Food Res 2017; 61. [PMID: 28133904 DOI: 10.1002/mnfr.201600947] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/23/2016] [Accepted: 01/11/2017] [Indexed: 11/09/2022]
Abstract
SCOPE Skeletal health is a lifelong process impacted by environmental factors, including nutrient intake. The n-3 source and PUFA ratio affect bone health in growing rats, or following ovariectomy (OVX), but no study has investigated the longitudinal effect of PUFA-supplementation throughout these periods of bone development. METHODS AND RESULTS One-month-old, Sprague-Dawley rats (n = 98) were randomized to receive one of four diets from 1 through 6 months of age. Diets were modified from AIN-93G to contain a varying amount and source of n-3 (flaxseed versus menhaden oil) to provide an n-6 to n-3 ratio of 10:1 or 5:1. At 3 (prior to SHAM or OVX) and 6 months of age, bone microarchitecture of the tibia was quantified using in vivo micro-computed tomography (SkyScan 1176, Bruker microCT). Providing 5:1 (flaxseed) resulted in lower trabecular thickness and medullary area and greater cortical area fraction during growth compared to diets with a 10:1 PUFA ratio, but many of these differences were not apparent following OVX. CONCLUSION PUFA-supplementation at levels attainable in human diet modulates some bone structure outcomes during periods of growth, but is not an adequate strategy for the prevention of OVX-induced bone loss in rats.
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Affiliation(s)
- Amanda B Longo
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ont, Canada
| | - Philip J Sullivan
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ont, Canada
| | - Sandra J Peters
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ont, Canada
| | - Paul J LeBlanc
- Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ont, Canada
| | - Gregory R Wohl
- Department of Mechanical Engineering, Faculty of Engineering, McMaster University, Hamilton, Ont, Canada
| | - Wendy E Ward
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ont, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ont, Canada
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23
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Fajardo VA, Trojanowski N, Castelli LM, Miotto PM, Amoye F, Ward WE, Tupling AR, LeBlanc PJ. Saturation of SERCA's lipid annulus may protect against its thermal inactivation. Biochem Biophys Res Commun 2017; 484:456-460. [PMID: 28137585 DOI: 10.1016/j.bbrc.2017.01.154] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 01/26/2017] [Indexed: 12/25/2022]
Abstract
The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) pumps are integral membrane proteins that catalyze the active transport of Ca2+ into the sarcoplasmic reticulum, thereby eliciting muscle relaxation. SERCA pumps are highly susceptible to oxidative damage, and cytoprotection of SERCA dampens thermal inactivation and is a viable therapeutic strategy in combating diseases where SERCA activity is impaired, such as muscular dystrophy. Here, we sought to determine whether increasing the percent of saturated fatty acids (SFA) within SERCA's lipid annulus through diet could protect SERCA pumps from thermal inactivation. Female Wistar rats were fed either a semi-purified control diet (AIN93G, 7% soybean oil by weight) or a modified AIN93G diet containing high SFA (20% lard by weight) for 17 weeks. Soleus muscles were extracted and SERCA lipid annulus and activity under thermal stress were analyzed. Our results show that SERCA's lipid annulus is abundant with short-chain (12-14 carbon) fatty acids, which corresponds well with SERCA's predicted bilayer thickness of 21 Å. Under control-fed conditions, SERCA's lipid annulus was already highly saturated (79%), and high-fat feeding did not increase this any further. High-fat feeding did not mitigate the reductions in SERCA activity seen with thermal stress; however, correlational analyses revealed significant and strong associations between % SFA and thermal stability of SERCA activity with greater %SFA being associated with lower thermal inactivation and greater % polyunsaturation and unsaturation index being associated with increased thermal inactivation. Altogether, these findings show that SERCA's lipid annulus may influence its susceptibility to oxidative damage, which could have implications in muscular dystrophy and age-related muscle wasting.
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Affiliation(s)
- Val Andrew Fajardo
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada; Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada; Department of Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Natalie Trojanowski
- Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada; Department of Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Laura M Castelli
- Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada; Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Paula M Miotto
- Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada; Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Foyinsola Amoye
- Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada; Department of Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Wendy E Ward
- Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada; Department of Health Sciences, Brock University, St. Catharines, ON, Canada; Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - A Russell Tupling
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada; Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Paul J LeBlanc
- Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada; Department of Health Sciences, Brock University, St. Catharines, ON, Canada.
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24
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Sacco SM, Saint C, Longo AB, Wakefield CB, Salmon PL, LeBlanc PJ, Ward WE. Repeated irradiation from micro-computed tomography scanning at 2, 4 and 6 months of age does not induce damage to tibial bone microstructure in male and female CD-1 mice. Bonekey Rep 2017; 6:855. [PMID: 28277563 DOI: 10.1038/bonekey.2016.87] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 11/10/2016] [Indexed: 11/09/2022]
Abstract
Long-term effects of repeated in vivo micro-computed tomography (μCT) scanning at key stages of growth and bone development (ages 2, 4 and 6 months) on trabecular and cortical bone structure, as well as developmental patterns, have not been studied. We determined the effect of repetitive μCT scanning at age 2, 4 and 6 months on tibia bone structure of male and female CD-1 mice and characterized developmental changes. At 2, 4 and 6 months of age, right tibias were scanned using in vivo μCT (Skyscan 1176) at one of three doses of radiation per scan: 222, 261 or 460 mGy. Left tibias of the same mice were scanned only at 6 months to serve as non-irradiated controls to determine whether recurrent radiation exposure alters trabecular and cortical bone structure at the proximal tibia. In males, eccentricity was lower (P<0.05) in irradiated compared with non-irradiated tibias (222 mGy group). Within each sex, all other structural outcomes were similar between irradiated and non-irradiated tibias regardless of dose. Trabecular bone loss occurred in all mice due to age while cortical development continued to age 6 months. In conclusion, repetitive μCT scans at various radiation doses did not damage trabecular or cortical bone structure of proximal tibia in male and female CD-1 mice. Moreover, scanning at 2, 4 and 6 months of age highlight the different developmental time course between trabecular and cortical bone. These scanning protocols can be used to investigate longitudinal responses of bone structures to an intervention.
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Affiliation(s)
- Sandra M Sacco
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St Catharines, Ontario, Canada; Centre for Bone and Muscle Health, Brock University, St Catharines, Ontario, Canada
| | - Caitlin Saint
- Centre for Bone and Muscle Health, Brock University, St Catharines, Ontario, Canada; Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St Catharines, Ontario, Canada
| | - Amanda B Longo
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St Catharines, Ontario, Canada; Centre for Bone and Muscle Health, Brock University, St Catharines, Ontario, Canada
| | - Charles B Wakefield
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St Catharines, Ontario, Canada; Centre for Bone and Muscle Health, Brock University, St Catharines, Ontario, Canada
| | | | - Paul J LeBlanc
- Centre for Bone and Muscle Health, Brock University, St Catharines, Ontario, Canada; Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St Catharines, Ontario, Canada
| | - Wendy E Ward
- Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St Catharines, Ontario, Canada; Centre for Bone and Muscle Health, Brock University, St Catharines, Ontario, Canada; Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St Catharines, Ontario, Canada
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25
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Snook LA, MacPherson REK, Monaco CMF, Frendo-Cumbo S, Castellani L, Peppler WT, Anderson ZG, Buzelle SL, LeBlanc PJ, Holloway GP, Wright DC. Prior exercise training blunts short-term high-fat diet-induced weight gain. Am J Physiol Regul Integr Comp Physiol 2016; 311:R315-24. [PMID: 27101294 DOI: 10.1152/ajpregu.00072.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/12/2016] [Indexed: 01/02/2023]
Abstract
High-fat diets rapidly cause weight gain and glucose intolerance. We sought to determine whether these changes could be mitigated with prior exercise training. Male C57BL/6J mice were exercise-trained by treadmill running (1 h/day, 5 days/wk) for 4 wk. Twenty-four hours after the final bout of exercise, mice were provided with a high-fat diet (HFD; 60% kcal from lard) for 4 days, with no further exercise. In mice fed the HFD prior to exercise training, the results were blunted weight gain, reduced fat mass, and a slight attenuation in glucose intolerance that was mirrored by greater insulin-induced Akt phosphorylation in skeletal muscle compared with sedentary mice fed the HFD. When ad libitum-fed sedentary mice were compared with sedentary high-fat fed mice that were calorie restricted (-30%) to match the weight gain of the previously trained high-fat fed mice, the same attenuated impairments in glucose tolerance were found. Blunted weight gain was associated with a greater capacity to increase energy expenditure in trained compared with sedentary mice when challenged with a HFD. Although mitochondrial enzymes in white adipose tissue and UCP-1 protein content in brown adipose tissue were increased in previously exercised compared with sedentary mice fed a HFD, ex vivo mitochondrial respiration was not increased in either tissue. Our data suggest that prior exercise training attenuates high-fat diet-induced weight gain and glucose intolerance and is associated with a greater ability to increase energy expenditure in response to a high-fat diet.
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Affiliation(s)
- Laelie A Snook
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Rebecca E K MacPherson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Cynthia M F Monaco
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Scott Frendo-Cumbo
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Laura Castellani
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Willem T Peppler
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Zachary G Anderson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Samyra L Buzelle
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - Paul J LeBlanc
- Department of Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada; and
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26
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Miotto PM, Castelli LM, Amoye F, Ward WE, LeBlanc PJ. High saturated fat diet alters the lipid composition of triacylglycerol and polar lipids in the femur of dam and offspring rats. Lipids 2015; 50:605-10. [PMID: 25920746 DOI: 10.1007/s11745-015-4023-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 04/13/2015] [Indexed: 11/28/2022]
Abstract
Previous work has shown that dietary lipids alter femur lipid composition. Specifically, we have shown that exposure to high saturated fatty acid (SFA) diets in utero, during suckling, or post-weaning alters femur total lipid composition, resulting in higher percent bone mass in males and females and bone mineral density (BMD) in female offspring with no effect on bone mineral outcomes in dams. Comparatively, high n-3 polyunsaturated fatty acid (PUFA) diets increase femur polar (PL) lipid n-3 content, which has been associated with increased bone mineral content and strength. However, the extent that PL or triacylglycerol (TAG) lipids change with high SFA diets is unknown. The current investigation examined the influence of a high SFA diet (20 % lard by weight) on femur PL and TAG lipid composition in 5-month old female Wistar rats (fed high SFA diet from age 28 days onwards; dams) and their 19-day old offspring (exposed to high SFA in utero and during suckling; pups). High SFA exposure resulted in increased monounsaturates and decreased n-3 and n-6 PUFA in the TAG fraction in both dams and pups, and higher SFA and n-6:n-3 ratio in dams only. The PL fraction showed decreased n-6 PUFA in both dams and pups. The magnitude of the diet-mediated responses, specifically TAG 18:1 and PL n-6 PUFA, may have contributed to the previously reported altered BMD, which was supported with correlation analysis. Future research should investigate the relationship of diet-induced changes in bone lipids on bone structure, as quantified through micro-computed tomography.
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Affiliation(s)
- Paula M Miotto
- Department of Health Sciences, Faculty of Applied Health Sciences, Centre for Bone and Muscle Health, Brock University, 500 Glenridge Ave., St., Catharines, ON, L2S 3A1, Canada
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27
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Ramos SV, Turnbull PC, MacPherson REK, LeBlanc PJ, Ward WE, Peters SJ. Changes in mitochondrial perilipin 3 and perilipin 5 protein content in rat skeletal muscle following endurance training and acute stimulated contraction. Exp Physiol 2015; 100:450-62. [PMID: 25663294 DOI: 10.1113/expphysiol.2014.084434] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 01/27/2015] [Indexed: 01/15/2023]
Abstract
NEW FINDINGS What is the central question of this study? The aim was to determine whether mitochondrial protein content of perilipin 3 (PLIN3) and perilipin 5 (PLIN5) is increased following endurance training and whether mitochondrial PLIN5 protein is increased to a greater extent in endurance-trained rats when compared with sedentary rats following acute contraction. What is the main finding and its importance? Mitochondrial PLIN3 but not PLIN5 protein was increased in endurance-trained compared with sedentary rats, suggesting a mitochondrial role for PLIN3 due to chronic exercise. Contrary to our hypothesis, acute mitochondrial PLIN5 protein was similar in both sedentary and endurance-trained rats. Endurance training results in an increased association between skeletal muscle lipid droplets and mitochondria. This association is likely to be important for the expected increase in intramuscular fatty acid oxidation that occurs with endurance training. The perilipin family of lipid droplet proteins, PLIN(2-5), are thought to play a role in skeletal muscle lipolysis. Recently, results from our laboratory demonstrated that skeletal muscle mitochondria contain PLIN3 and PLIN5 protein. Furthermore, 30 min of stimulated contraction induces an increased mitochondrial PLIN5 content. To determine whether mitochondrial content of PLIN3 and PLIN5 is altered with endurance training, Sprague-Dawley rats were randomized into sedentary or endurance-trained groups for 8 weeks of treadmill running followed by an acute (30 min) sciatic nerve stimulation to induce lipolysis. Mitochondrial PLIN3 protein was ∼1.5-fold higher in red gastrocnemius of endurance-trained rats compared with sedentary animals, with no change in mitochondrial PLIN5 protein. In addition, there was an increase in plantaris intramuscular lipid storage. Acute electrically stimulated contraction in red gastrocnemius from sedentary and endurance-trained rats resulted in a similar increase of mitochondrial PLIN5 between these two groups, with no net change in PLIN3 in either group. Plantaris intramuscular lipid content decreased to a similar extent in sedentary and endurance-trained rats. These results suggest that while total mitochondrial PLIN5 content is not altered by endurance training, PLIN5 does have an acute role in the mitochondrial fraction during muscle contraction. Conversely, mitochondrial PLIN3 does not change acutely with muscle contraction, but PLIN3 content was increased following endurance training, indicating a role in chronic adaptations of skeletal muscle.
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Affiliation(s)
- S V Ramos
- Center for Bone and Muscle Health, Brock University, St Catharines, Ontario, Canada; Department of Kinesiology, Brock University, St Catharines, Ontario, Canada
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28
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MacPherson REK, Castelli LM, Miotto PM, Frendo-Cumbo S, Milburn A, Roy BD, LeBlanc PJ, Ward WE, Peters SJ. A maternal high fat diet has long-lasting effects on skeletal muscle lipid and PLIN protein content in rat offspring at young adulthood. Lipids 2015; 50:205-17. [PMID: 25552350 DOI: 10.1007/s11745-014-3985-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 12/16/2014] [Indexed: 01/08/2023]
Abstract
A maternal high fat diet (HFD) can have adverse effects on skeletal muscle development. Skeletal muscle PLIN proteins (PLIN2, 3 and 5) are thought to play critical roles in lipid metabolism, however effects of HFD on PLIN and lipases (HSL, ATGL, CGI-58) in mothers as well as their offspring have yet to be investigated. The primary objective of this study was to determine whether maternal HFD would influence skeletal muscle lipase and PLIN protein content in offspring at weaning (19 d) and young adulthood (3 mo). Female rats (28 d old, n = 9/group) were fed control (CON, AIN93G, 7% soybean oil) or HFD (AIN93G, 20% lard) for 10 weeks prior to mating and throughout pregnancy and lactation. All offspring were weaned to CON [n = 18/group, 1 female and 1 male pup per litter were studied at weaning (19 d) and 3 mo of age]. There was no effect of sex for the main outcomes measured in plantaris, therefore male and female data was combined. Maternal HFD resulted in higher triacylglycerol content in pups at 3 mo (p < 0.05), as well as in the dams (p = 0.015). Maternal HFD resulted in higher PLIN5 content in pups at weaning and 3 mo (p = 0.05). PLIN2 and PLIN5 content decreased at 3 mo versus weaning (p < 0.001). HFD dams had a higher PLIN3 content (p = 0.016). Diet had no effect on ATGL, CGI-58, or HSL content. In conclusion, exposure to a maternal HFD resulted in higher skeletal muscle lipid and PLIN5 content in plantaris of offspring through to young adulthood.
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Affiliation(s)
- Rebecca E K MacPherson
- Faculty of Applied Health Sciences, Center for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada,
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Herbst EAF, MacPherson REK, LeBlanc PJ, Roy BD, Jeoung NH, Harris RA, Peters SJ. Pyruvate dehydrogenase kinase-4 contributes to the recirculation of gluconeogenic precursors during postexercise glycogen recovery. Am J Physiol Regul Integr Comp Physiol 2013; 306:R102-7. [PMID: 24305065 DOI: 10.1152/ajpregu.00150.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During recovery from glycogen-depleting exercise, there is a shift from carbohydrate oxidation to glycogen resynthesis. The activity of the pyruvate dehydrogenase (PDH) complex may decrease to reduce oxidation of carbohydrates in favor of increasing gluconeogenic recycling of carbohydrate-derived substrates for this process. The precise mechanism behind this has yet to be elucidated; however, research examining mRNA content has suggested that the less-abundant pyruvate dehydrogenase kinase-4 (PDK4) may reduce PDH activation during exercise recovery. To investigate this, skeletal muscle and liver of wild-type (WT) and PDK4-knockout (PDK4-KO) mice were analyzed at rest (Rest), after exercise to exhaustion (Exh), and after 2 h of recovery with ad libitum feeding (Rec). Although there were no differences in exercise tolerance between genotypes, caloric consumption was doubled by PDK4-KO mice during Rec. Because of this, PDK4-KO mice at Rec supercompensated muscle glycogen to 120% of resting stores. Therefore, an extra group of PDK4-KO mice were pair-fed (PF) with WT mice during Rec for comparison. PF mice fully replenished muscle glycogen but recovered only 50% of liver glycogen stores. Concentrations of muscle lactate and alanine were also lower in PF than in WT mice, indicating that this decrease may lead to a potential reduction of recycled gluconeogenic substrates, due to oxidation of their carbohydrate precursors in skeletal muscle, leading to observed reductions in hepatic glucose and glycogen concentrations. Because of the impairments seen in PF PDK4-KO mice, these results suggest a role for PDK4 in regulating the PDH complex in muscle and promoting gluconeogenic precursor recirculation during recovery from exhaustive exercise.
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Affiliation(s)
- Eric A F Herbst
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
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Farlinger CM, Lui AJ, Harrison RC, LeBlanc PJ, Peters SJ, Roy BD. Extracellular hyperosmotic stress stimulates glucose uptake in incubated fast-twitch rat skeletal muscle. Appl Physiol Nutr Metab 2013; 38:605-12. [DOI: 10.1139/apnm-2012-0236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The influence of hyperosmotic stress on glucose uptake, handling, and signaling processes remains unclear in mammalian skeletal muscle. Thus, the purpose of this study was to investigate alterations in glucose uptake and handling during extracellular hyperosmotic stress in isolated fast-twitch mammalian skeletal muscle. Using an established in vitro isolated whole-muscle model, extensor digitorum longus (EDL) muscles were dissected from male rats (4–6 weeks of age) and incubated (30–60 min) in an organ bath, containing Sigma Medium-199 with 8 mmol·L−1D-glucose, and mannitol was added to the targeted osmolalities (ISO, iso-osmotic, 290 mmol·kg−1; HYPER, hyperosmotic, 400 mmol·kg−1). Results demonstrate that relative water content decreased in HYPER. HYPER resulted in significant alterations in muscle metabolite concentrations (lower glycogen, elevated lactate, and glucose-6-phosphate), suggesting a decrease in energy charge. Glucose uptake was also found to be higher in HYPER, and AS160 (implicated in insulin- and contraction-mediated glucose uptake) was found to be significantly more phosphorylated in HYPER than in ISO after 30 min. In conclusion, glucose uptake and handling is altered with hyperosmotic extracellular stress in the fast-twitch EDL. The increases in glucose uptake might be facilitated through alterations in AS160 signaling after 30 to 60 min of osmotic stress.
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Affiliation(s)
- Chris M. Farlinger
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Adrian J. Lui
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Rose C. Harrison
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Paul J. LeBlanc
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada; Centre for Bone and Muscle Health, Brock University, St. Catharines, ON L2S 3A1, Canada; Department of Community Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Sandra J. Peters
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada; Centre for Bone and Muscle Health, Brock University, St. Catharines, ON L2S 3A1, Canada; Department of Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Brian D. Roy
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada; Centre for Bone and Muscle Health, Brock University, St. Catharines, ON L2S 3A1, Canada; Department of Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada
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Miotto PM, Castelli LM, MacPherson RE, Johnston BD, LeBlanc PJ, Roy BD, Peters SJ, Ward WE. Maternal high fat diet results in altered body composition in first generation male offspring at weaning but not adulthood. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.244.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | - Paul J LeBlanc
- Community Health SciencesBrock UniversitySt. CatharinesONCanada
| | - Brian D Roy
- KinesiologyBrock UniversitySt. CatharinesONCanada
| | | | - Wendy E Ward
- KinesiologyBrock UniversitySt. CatharinesONCanada
- Community Health SciencesBrock UniversitySt. CatharinesONCanada
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Zibamanzarmofrad M, Basic A, Doering J, Schmelz EM, Grange RW, LeBlanc PJ. Impact of sphingomyelin‐supplemented diet on phospholipid composition in diaphragm of mdx mice. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.lb416] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Eva M Schmelz
- Human Nutrition, Foods and ExerciseVirginia TechBlacksburgVA
| | - Robert W Grange
- Human Nutrition, Foods and ExerciseVirginia TechBlacksburgVA
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Amoye F, Castelli LM, Miotto PM, MacPherson REK, Johnston BD, Basic A, Trojanowski N, Roy BD, Ward WE, LeBlanc PJ. Impact of maternal high saturated fat diet on bone lipid content in weanling and 3 month old female offspring. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.lb415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Castelli LM, Miotto PM, MacPherson REK, Johnston BD, LeBlanc PJ, Peters SJ, Roy BD, Ward WE. Maternal high fat feeding results in higher fat mass and bone mineral content in weanling but not 3 month old female offspring. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.244.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | - Paul J LeBlanc
- Community Health SciencesBrock UniversitySt. CatharinesONCanada
| | | | - Brian D Roy
- KinesiologyBrock UniversitySt. CatharinesONCanada
| | - Wendy E Ward
- Community Health SciencesBrock UniversitySt. CatharinesONCanada
- KinesiologyBrock UniversitySt. CatharinesONCanada
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Fajardo VA, McMeekin L, Basic A, Lamb GD, Murphy RM, LeBlanc PJ. Isolation of sarcolemmal plasma membranes by mechanically skinning rat skeletal muscle fibers for phospholipid analysis. Lipids 2013; 48:421-30. [PMID: 23430510 DOI: 10.1007/s11745-013-3770-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 01/28/2013] [Indexed: 12/21/2022]
Abstract
Membrane phospholipid (PL) composition has been shown to affect cellular function by altering membrane physical structure. The sarcolemma plasma membrane (SLpm) is integral to skeletal muscle function and health. Previous studies assessing SLpm PL composition have demonstrated contamination from transverse (t)-tubule, sarcoplasmic reticulum, and nuclear membranes. This study assessed the possibility of isolating SL by mechanically skinning skeletal muscle fiber segments for the analysis of SLpm PL composition. Mechanically skinned SLpm from rat extensor digitorum longus (EDL) muscle fibers underwent Western blot analysis to assess contamination from t-tubule, sarcoplasmic reticulum, nuclear and mitochondrial membranes. The results indicate that isolated SLpm had minimal nuclear and mitochondrial membrane contamination and was void of contamination from sarcoplasmic reticulum and t-tubule membranes. After performing both high-performance thin layer chromatography and gas chromatography, we found that the SLpm obtained by mechanical skinning had higher sphingomyelin and total fatty acid saturation and lower phosphatidylcholine when compared to previous literature. Thus, by avoiding the use of various chemical treatments and membrane fractionation, we present data that may truly represent the SLpm and future studies can use this technique to assess potential changes under various perturbations and disease conditions such as insulin resistance and muscular dystrophy.
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Affiliation(s)
- Val Andrew Fajardo
- Faculty of Applied Health Sciences, Centre for Bone and Muscle Health, Brock University, 500 Glenridge Ave, St. Catharines, ON L2S 3A1, Canada
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Wahi G, LeBlanc PJ, Hay JA, Faught BE, O'Leary D, Cairney J. Metabolic syndrome in children with and without developmental coordination disorder. Res Dev Disabil 2011; 32:2785-2789. [PMID: 21708447 DOI: 10.1016/j.ridd.2011.05.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2011] [Revised: 05/16/2011] [Accepted: 05/16/2011] [Indexed: 05/31/2023]
Abstract
Children with developmental coordination disorder (DCD) have higher rates of obesity compared to children with typical motor development, and, as a result may be at increased risk for developing metabolic syndrome (MetS). The purpose of this study was to determine the presence of MetS and its components among children with and without DCD. This nested case-control study classified 63 children scoring below the 16th percentile on the Movement Assessment Battery for Children (M-ABC-2) as probable DCD (pDCD), and 63 controls, all of whom scored above the 16th percentile. Metabolic syndrome was defined using the International Diabetes Federation (IDF) criteria. Eleven children met the criteria for MetS; 8 (72.3%) with pDCD and 3 (27.3%) controls (p = 0.115). Abdominal obesity was found in 39 (30.9%) of children, 29 (46.0%) with pDCD and 10 (15.9%) controls (p < 0.01). Serum triglycerides were higher in pDCD compared to controls, 91.9 mg/dl (63.1) vs. 67.7 mg/dl (33.3) in the control group, p = 0.001. Blood pressure was also significantly higher in the pDCD group, mean systolic BP (110 vs. 105 mmHg, p = 0.01) and mean diastolic BP (69 vs. 65 mmHg, p = 0.01). There were no statistically significant differences between the groups for other components of MetS. The higher prevalence of abdominal obesity and elevated triglycerides and blood pressure in children with pDCD may put them at risk of meeting all criteria of MetS earlier then their peers.
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Affiliation(s)
- Gita Wahi
- Department of Pediatrics, McMaster University, Hamilton, ON, Canada
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Love LK, LeBlanc PJ, Inglis JG, Bradley NS, Choptiany J, Heigenhauser GJF, Peters SJ. The relationship between human skeletal muscle pyruvate dehydrogenase phosphatase activity and muscle aerobic capacity. J Appl Physiol (1985) 2011; 111:427-34. [DOI: 10.1152/japplphysiol.00672.2010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pyruvate dehydrogenase (PDH) is a mitochondrial enzyme responsible for regulating the conversion of pyruvate to acetyl-CoA for use in the tricarboxylic acid cycle. PDH is regulated through phosphorylation and inactivation by PDH kinase (PDK) and dephosphorylation and activation by PDH phosphatase (PDP). The effect of endurance training on PDK in humans has been investigated; however, to date no study has examined the effect of endurance training on PDP in humans. Therefore, the purpose of this study was to examine differences in PDP activity and PDP1 protein content in human skeletal muscle across a range of muscle aerobic capacities. This association is important as higher PDP activity and protein content will allow for increased activation of PDH, and carbohydrate oxidation. The main findings of this study were that 1) PDP activity ( r2 = 0.399, P = 0.001) and PDP1 protein expression ( r2 = 0.153, P = 0.039) were positively correlated with citrate synthase (CS) activity as a marker for muscle aerobic capacity; 2) E1α ( r2 = 0.310, P = 0.002) and PDK2 protein ( r2 = 0.229, P =0.012) are positively correlated with muscle CS activity; and 3) although it is the most abundant isoform, PDP1 protein content only explained ∼18% of the variance in PDP activity ( r2 = 0.184, P = 0.033). In addition, PDP1 in combination with E1α explained ∼38% of the variance in PDP activity ( r2 = 0.383, P = 0.005), suggesting that there may be alternative regulatory mechanisms of this enzyme other than protein content. These data suggest that with higher muscle aerobic capacity (CS activity) there is a greater capacity for carbohydrate oxidation (E1α), in concert with higher potential for PDH activation (PDP activity).
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Affiliation(s)
- Lorenzo K. Love
- Department of Kinesiology,
- Centre for Muscle Metabolism and Biophysics, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario
| | - Paul J. LeBlanc
- Centre for Muscle Metabolism and Biophysics, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario
| | - J. Greig Inglis
- Centre for Muscle Metabolism and Biophysics, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario
| | - Nicolette S. Bradley
- Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jon Choptiany
- Department of Kinesiology,
- Centre for Muscle Metabolism and Biophysics, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario
| | | | - Sandra J. Peters
- Department of Kinesiology,
- Centre for Muscle Metabolism and Biophysics, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario
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Dunford EC, Herbst EA, Jeoung NH, Gittings W, Inglis JG, Vandenboom R, LeBlanc PJ, Harris RA, Peters SJ. PDH activation during in vitro muscle contractions in PDH kinase 2 knockout mice: effect of PDH kinase 1 compensation. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1487-93. [PMID: 21411764 DOI: 10.1152/ajpregu.00498.2010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Pyruvate dehydrogenase (PDH) plays an important role in regulating carbohydrate oxidation in skeletal muscle. PDH is deactivated by a set of PDH kinases (PDK1, PDK2, PDK3, PDK4), with PDK2 and PDK4 being the most predominant isoforms in skeletal muscle. Although PDK2 is the most abundant isoform, few studies have examined its physiological role. The role of PDK2 on PDH activation (PDHa) at rest and during muscle stimulation at 10 and 40 Hz (eliciting low- and moderate-intensity muscle contractions, respectively) in isolated extensor digitorum longus muscles was studied in PDK2 knockout (PDK2KO) and wild-type (WT) mice (n = 5 per group). PDHa activity was unexpectedly 35 and 77% lower in PDK2KO than WT muscle (P = 0.043), while total PDK activity was nearly fourfold lower in PDK2KO muscle (P = 0.006). During 40-Hz contractions, initial force was lower in PDK2KO than WT muscle (P < 0.001) but fatigued similarly to ∼75% of initial force by 3 min. There were no differences in initial force or rate of fatigue during 10-Hz contractions. PDK1 compensated for the lack of PDK2 and was 1.8-fold higher in PDK2KO than WT muscle (P = 0.019). This likely contributed to ensuring that resting PDHa activity was similar between the groups and accounts for the lower PDH activation during muscle contraction, as PDK1 is a very potent inhibitor of the PDH complex. Increased PDK1 expression appears to be regulated by hypoxia inducible factor-1α, which was 3.5-fold higher in PDK2KO muscle. It is clear that PDK2 activity is essential, even at rest, in regulation of carbohydrate oxidation and production of reducing equivalents for the electron transport chain. In addition, these results underscore the importance of the overall kinetics of the PDK isoform population, rather than total PDK activity, in determining transformation of the PDH complex and PDHa activity during muscle contraction.
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Affiliation(s)
- Emily C Dunford
- Centre for Muscle Metabolism and Biophysics, Brock University, St. Catharines, Ontario, Canada
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Stefanyk LE, Coverdale N, Roy BD, Peters SJ, LeBlanc PJ. Skeletal Muscle Type Comparison of Subsarcolemmal Mitochondrial Membrane Phospholipid Fatty Acid Composition in Rat. J Membr Biol 2010; 234:207-15. [DOI: 10.1007/s00232-010-9247-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Accepted: 03/04/2010] [Indexed: 12/22/2022]
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Cermak NM, LeBlanc PJ, Peters SJ, Vandenboom R, Roy BD. Effect of extracellular osmolality on metabolism in contracting mammalian skeletal muscle in vitro. Appl Physiol Nutr Metab 2009; 34:1055-64. [DOI: 10.1139/h09-106] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Extensive research has been conducted on hepatocyte metabolism perturbed under the influence of anisosmotic stress. However, much less is known about the behaviour of skeletal muscle metabolism under similar conditions. After establishing a working model to study anisosmotic stress in resting mammalian skeletal muscle, the current study tested the hypothesis that hyperosmotic (HYPER) stress would lead to increased creatine, lactate, and measured enzyme activity, whereas hypo-osmotic (HYPO) stress would lead to decreased metabolites and enzyme activity vs. iso-osmotic (ISO) stress post contraction. Rat soleus (SOL) and extensor digitorum longus (EDL) were isolated and incubated in an organ bath (95% O2, 5% CO2, pH 7.4, 25 °C) altered to targeted osmotic conditions (ISO, 290 osmol·L–1; HYPO, 180 osmol·L–1; HYPER, 400 osmol·L–1). Muscle samples were flash frozen after 10 min of contraction. Post contraction, muscle water content in the SOL HYPO condition was 18% greater than ISO, and HYPER had approximately 14% less water content than ISO (p < 0.05). In the HYPO condition, EDL had 21% greater water content than ISO, and HYPER had 17% less water content than ISO (p < 0.05). SOL HYPO resulted in higher phosphocreatine and lower lactate and creatine vs. HYPER (p < 0.05) but there were no differences in EDL between HYPO and HYPER. Pyruvate dehydrogenase activity increased in SOL HYPER vs. HYPO, whereas glycogen phosphorylase a increased in EDL HYPER vs. HYPO. In conclusion, fibre-type-specific responses exist after contraction such that when SOL muscle is perturbed in HYPER, as compared with HYPO, media, metabolic activity increases. Future work should focus on glucose uptake–regulation during anisosmotic conditions.
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Affiliation(s)
- Naomi M. Cermak
- Centre for Muscle Metabolism and Biophysics, Department of Physical Education and Kinesiology, Faculty of Applied Health Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, ON L2S 3A1, Canada
| | - Paul J. LeBlanc
- Centre for Muscle Metabolism and Biophysics, Department of Physical Education and Kinesiology, Faculty of Applied Health Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, ON L2S 3A1, Canada
| | - Sandra J. Peters
- Centre for Muscle Metabolism and Biophysics, Department of Physical Education and Kinesiology, Faculty of Applied Health Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, ON L2S 3A1, Canada
| | - Rene Vandenboom
- Centre for Muscle Metabolism and Biophysics, Department of Physical Education and Kinesiology, Faculty of Applied Health Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, ON L2S 3A1, Canada
| | - Brian D. Roy
- Centre for Muscle Metabolism and Biophysics, Department of Physical Education and Kinesiology, Faculty of Applied Health Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, ON L2S 3A1, Canada
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Bigrigg JK, Heigenhauser GJF, Inglis JG, LeBlanc PJ, Peters SJ. Carbohydrate refeeding after a high-fat diet rapidly reverses the adaptive increase in human skeletal muscle PDH kinase activity. Am J Physiol Regul Integr Comp Physiol 2009; 297:R885-91. [PMID: 19625693 DOI: 10.1152/ajpregu.90604.2008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pyruvate dehydrogenase (PDH) regulates oxidative carbohydrate disposal in skeletal muscle and is downregulated by reversible phosphorylation catalyzed by PDH kinase (PDK). Previous work has demonstrated increased PDK activity and PDK4 expression in human skeletal muscle following a high-fat low-carbohydrate (HF) diet, which leads to decreased PDH in the active form (PDHa activity) and carbohydrate oxidation. The purpose of this study was to examine the time course of changes in PDK and PDHa activities with refeeding of carbohydrates after an HF diet in human skeletal muscle. Healthy male volunteers (n = 8) consumed a standardized 3-day Pre-diet with the same energy content as their habitual diet, followed by a eucaloric 6-day HF diet (Pre-diet: 50:30:20%; HF diet: 5:75:20%; carbohydrate/fat/protein). Muscle biopsies were taken before and after the HF diet and at 45 min and 3 h after carbohydrate refeeding with a single high-glycemic index carbohydrate meal (88:5:7% carbohydrate/fat/protein) representing approximately one third of the individual subject's habitual energy intake. PDK activity increased from 0.08 +/- 0.01 Pre- to 0.25 +/- 0.02 min (P < 0.001) Post-HF diet, and decreased with carbohydrate refeeding to 0.17 +/- 0.05 (P = 0.014) and 0.11 +/- 0.01 min (P = 0.006) at 45 min and 3 h, respectively. PDHa decreased from 0.89 +/- 0.20 to 0.32 +/- 0.05 (P = 0.007) mmol x min(-1) x kg wet wt(-1) following the HF diet, and was increased transiently with refeeding at 45 min, but returned to lower values by 3 h (P = 0.025 compared with Pre). The potential mechanism(s) for this attenuation of PDHa activity remains unclear. These data demonstrate that in human skeletal muscle, the adaptive increase in PDK activity following an HF diet is rapidly reversed to Pre-diet activity levels within 45 min to 3 h, and this is accompanied by a short-term increase in PDHa activity.
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Affiliation(s)
- J Kent Bigrigg
- Faculty of Applied Health Sciences, Brock Univ., St. Catharines, ON, Canada L2S 3A1
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Gurd BJ, Peters SJ, Heigenhauser GJF, LeBlanc PJ, Doherty TJ, Paterson DH, Kowalchuk JM. Prior heavy exercise elevates pyruvate dehydrogenase activity and muscle oxygenation and speeds O2 uptake kinetics during moderate exercise in older adults. Am J Physiol Regul Integr Comp Physiol 2009; 297:R877-84. [PMID: 19605760 DOI: 10.1152/ajpregu.90848.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The adaptation of pulmonary oxygen uptake (VO(2)(p)) kinetics during the transition to moderate-intensity exercise is slowed in older compared with younger adults; however, this response is faster following a prior bout of heavy-intensity exercise. We have examined VO(2)(p) kinetics, pyruvate dehydrogenase (PDH) activation, muscle metabolite contents, and muscle deoxygenation in older adults [n = 6; 70 +/- 5 (67-74) yr] during moderate-intensity exercise (Mod(1)) and during moderate-intensity exercise preceded by heavy-intensity warm-up exercise (Mod(2)). The phase 2 VO(2)(p) time constant (tauVO(2)(p)) was reduced (P < 0.05) in Mod(2) (29 +/- 5 s) compared with Mod(1) (39 +/- 14 s). PDH activity was elevated (P < 0.05) at baseline prior to Mod(2) (2.1 +/- 0.6 vs. 1.2 +/- 0.3 mmol acetyl-CoA x min(-1) x kg wet wt(-1)), and the delay in attaining end-exercise activity was abolished. Phosphocreatine breakdown during exercise was reduced (P < 0.05) at both 30 s and 6 min in Mod(2) compared with Mod(1). Near-infrared spectroscopy-derived indices of muscle oxygenation were elevated both prior to and throughout Mod(2), while muscle deoxygenation kinetics were not different between exercise bouts consistent with elevated perfusion and O(2) availability. These results suggest that in older adults, faster VO(2)(p) kinetics following prior heavy-intensity exercise are likely a result of prior activation of mitochondrial enzyme activity in combination with elevated muscle perfusion and O(2) availability.
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Affiliation(s)
- Brendon J Gurd
- Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, The Univ. of Western Ontario, London, Ontario, Canada N6A 5B9
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LeBlanc PJ, Mulligan M, Antolić A, MacPherson L, Inglis JG, Martin D, Roy BD, Peters SJ. Skeletal muscle type comparison of pyruvate dehydrogenase phosphatase activity and isoform expression: effects of obesity and endurance training. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1224-30. [DOI: 10.1152/ajpregu.90320.2008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pyruvate dehydrogenase (PDH) plays an important role in regulating carbohydrate metabolism in skeletal muscle. PDH is activated by PDH phosphatase (PDP) and deactivated by PDH kinase (PDK). Obesity has a large negative impact on skeletal muscle carbohydrate metabolism, whereas endurance training has been shown to improve regulatory control of skeletal muscle carbohydrate metabolism, more so when coupled with obesity. A majority of this literature has focused on PDK, with little information available on PDP. To determine the relative role of PDP in regulating skeletal muscle PDH activity with obesity and endurance training, obese and lean Zucker rats remained sedentary or were endurance trained (1 h/day, 5 days/wk) for a period of 8 wk. Soleus, red gastrocnemius, (RG), and white gastrocnemius (WG) muscles were sampled after the training period. The main findings were 1) obesity resulted in a 46% decrease in PDP activity expressed per milligram extracted mitochondrial protein only in RG, while PDP isoform content was unchanged; 2) 8 wk of endurance training led to a significant 1.4–2.2-fold increase in PDP activity of all muscle examined from obese rats, and the concomitant increase in PDP1 protein was only seen in soleus and RG; 3) 8 wk of endurance training led to a trending 1.4–2.2-fold increase in PDP activity of all muscle examined from obese rats, and the concomitant increase in PDP1 protein was only seen in soleus and RG; and 4) PDP2 protein content was not affected by obesity or training. These results suggest that decreased PDP activity in oxidative skeletal muscles may play a role in the impairment of carbohydrate metabolism in obese rats, which is reversible with endurance training.
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Bradley NS, Heigenhauser GJF, Roy BD, Staples EM, Inglis JG, LeBlanc PJ, Peters SJ. The acute effects of differential dietary fatty acids on human skeletal muscle pyruvate dehydrogenase activity. J Appl Physiol (1985) 2007; 104:1-9. [PMID: 17947500 DOI: 10.1152/japplphysiol.00636.2007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pyruvate dehydrogenase (PDH) is an important regulator of carbohydrate oxidation during exercise, and its activity can be downregulated by an increase in dietary fat. The purpose of this study was to determine the acute metabolic effects of differential dietary fatty acids on the activation of the PDH complex (PDHa activity) at rest and at the onset of moderate-intensity exercise. University-aged male subjects (n = 7) underwent two fat-loading trials spaced at least 2 wk apart. Subjects consumed approximately 300 g saturated (SFA) or n-6 polyunsaturated fatty acid (PUFA) fat over the course of 5 h. Following this, participants cycled at 65% of their maximum oxygen uptake for 15 min. Muscle biopsies were taken before and following fat loading and at 1 min exercise. Plasma free fatty acids increased from 0.15 +/- 0.07 to 0.54 +/- 0.19 mM over 5 h with SFA and from 0.11 +/- 0.04 to 0.35 +/- 0.13 mM with n-6 PUFA and were significantly lower throughout the n-6 PUFA trial. PDHa activity was unchanged following fat loading but increased at the onset of exercise in the SFA trial, from 1.18 +/- 0.27 to 2.16 +/- 0.37 mmol x min(-1) x kg wet wt(-1). This effect was negated in the n-6 PUFA trial (1.04 +/- 0.20 to 1.28 +/- 0.36 mmol x min(-1) x kg wet wt(-1)). PDH kinase was unchanged in both trials, suggesting that the attenuation of PDHa activity with n-6 PUFA was a result of changes in the concentrations of intramitochondrial effectors, potentially intramitochondrial NADH or Ca(2+). Our findings suggest that attenuated PDHa activity contributes to the preferential oxidation of n-6 PUFA during moderate-intensity exercise.
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Affiliation(s)
- Nicolette S Bradley
- Faculty of Applied Health Sciences, Brock Univ., St. Catharines, Ontario, Canada
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Martin DM, Harris RA, Vandenboom R, LeBlanc PJ, Roy BD, Jeoung NH, Peters SJ. Pyruvate dehydrogenase (PDH) activity in response to skeletal muscle contraction at two stimulation frequencies in PDH kinase 4 knockout mice. FASEB J 2007. [DOI: 10.1096/fasebj.21.6.a1355-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Dale Marie Martin
- Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesL2S 3A1Canada
| | - R A Harris
- School of MedicineIndiana University1120 South DriveIndianapolisIN46202‐5114
| | - R Vandenboom
- Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesL2S 3A1Canada
| | - P J LeBlanc
- Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesL2S 3A1Canada
| | - B D Roy
- Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesL2S 3A1Canada
| | - N H Jeoung
- School of MedicineIndiana University1120 South DriveIndianapolisIN46202‐5114
| | - Sandra J Peters
- Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesL2S 3A1Canada
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Gurd BJ, Peters SJ, Heigenhauser GJF, LeBlanc PJ, Doherty TJ, Paterson DH, Kowalchuk JM. Prior heavy exercise elevates pyruvate dehydrogenase activity and speeds O2 uptake kinetics during subsequent moderate-intensity exercise in healthy young adults. J Physiol 2006; 577:985-96. [PMID: 16990406 PMCID: PMC1890376 DOI: 10.1113/jphysiol.2006.112706] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
The adaptation of pulmonary oxygen uptake (.VO2) during the transition to moderate-intensity exercise (Mod) is faster following a prior bout of heavy-intensity exercise. In the present study we examined the activation of pyruvate dehydrogenase (PDHa) during Mod both with and without prior heavy-intensity exercise. Subjects (n = 9) performed a Mod(1)-heavy-intensity-Mod(2) exercise protocol preceded by 20 W baseline. Breath-by-breath .VO2 kinetics and near-infrared spectroscopy-derived muscle oxygenation were measured continuously, and muscle biopsy samples were taken at specific times during the transition to Mod. In Mod(1), PDHa increased from baseline (1.08 +/- 0.2 mmol min(-1) (kg wet wt)(-1)) to 30 s (2.05 +/- 0.2 mmol min(-1) (kg wet wt)(-1)), with no additional change at 6 min exercise (2.07 +/- 0.3 mmol min(-1) (kg wet wt)(-1)). In Mod(2), PDHa was already elevated at baseline (1.88 +/- 0.3 mmol min(-1) (kg wet wt)(-1)) and was greater than in Mod(1), and did not change at 30 s (1.96 +/- 0.2 mmol min(-1) (kg wet wt)(-1)) but increased at 6 min exercise (2.70 +/- 0.3 mmol min(-1) (kg wet wt)(-1)). The time constant of .VO2 was lower in Mod(2) (19 +/- 2 s) than Mod(1) (24 +/- 3 s). Phosphocreatine (PCr) breakdown from baseline to 30 s was greater (P < 0.05) in Mod(1) (13.6 +/- 6.7 mmol (kg dry wt)(-1)) than Mod(2) (6.5 +/- 6.2 mmol (kg dry wt)(-1)) but total PCr breakdown was similar between conditions (Mod(1), 14.8 +/- 7.4 mmol (kg dry wt)(-1); Mod(2), 20.1 +/- 8.0 mmol (kg dry wt)(-1)). Both oxyhaemoglobin and total haemoglobin were elevated prior to and throughout Mod(2) compared with Mod(1). In conclusion, the greater PDHa at baseline prior to Mod(2) compared with Mod(1) may have contributed in part to the faster .VO2 kinetics in Mod(2). That oxyhaemoglobin and total haemoglobin were elevated prior to Mod(2) suggests that greater muscle perfusion may also have contributed to the observed faster .VO2 kinetics. These findings are consistent with metabolic inertia, via delayed activation of PDH, in part limiting the adaptation of pulmonary .VO2 and muscle O2 consumption during the normal transition to exercise.
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Affiliation(s)
- B J Gurd
- Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, HSB 411C, The University of Western Ontario, London, Ontario, Canada N6A 5B9
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Stellingwerff T, LeBlanc PJ, Hollidge MG, Heigenhauser GG, Spriet LL. Hyperoxia Decreases Muscle Glycogenolysis, Pyruvate and Lactate Production during Steady State Exercise. Med Sci Sports Exerc 2006. [DOI: 10.1249/00005768-200605001-00959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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MacPherson LL, LeBlanc PJ, Inglis JG, Roy BD, Peters SJ. Adaptation of skeletal muscle pyruvate dehydrogenase kinase in response to starvation in mitochondrial subpopulations. FASEB J 2006. [DOI: 10.1096/fasebj.20.5.lb26-d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Laura Lynn MacPherson
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2S3A1Canada
| | - Paul J. LeBlanc
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2S3A1Canada
| | - J. Greig Inglis
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2S3A1Canada
| | - Brian D. Roy
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2S3A1Canada
| | - Sandra J. Peters
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2S3A1Canada
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LeBlanc PJ, Mulligan M, Antolic A, MacPherson L, Inglis JG, Martin D, Roy BD, Peters SJ. Skeletal muscle pyruvate dehydrogenase phosphatase: effects of obesity and endurance training. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a815-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Paul J LeBlanc
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2A 3S1Canada
| | - Matt Mulligan
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2A 3S1Canada
| | - AnaMaria Antolic
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2A 3S1Canada
| | - Laura MacPherson
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2A 3S1Canada
| | - J. Greig Inglis
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2A 3S1Canada
| | - Dale Martin
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2A 3S1Canada
| | - Brian D Roy
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2A 3S1Canada
| | - Sandra J Peters
- Faculty of Applied Health SciencesBrock University500 Glenridge AveSt. CatharinesOntarioL2A 3S1Canada
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Watt MJ, Heigenhauser GJF, LeBlanc PJ, Inglis JG, Spriet LL, Peters SJ. Rapid upregulation of pyruvate dehydrogenase kinase activity in human skeletal muscle during prolonged exercise. J Appl Physiol (1985) 2004; 97:1261-7. [PMID: 15169745 DOI: 10.1152/japplphysiol.00132.2004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Prolonged moderate-intensity exercise is characterized by a progressive reduction in carbohydrate oxidation and concomitant increase in fat oxidation. Pyruvate dehydrogenase (PDH) controls the entry of pyruvate into oxidative pathways and is a rate-limiting enzyme for carbohydrate metabolism. PDH is controlled by the activities of a kinase (PDK, inhibitory) and phosphatase (stimulatory). To test the hypothesis that increased PDK activity was associated with decreased PDH activity and carbohydrate oxidation during an acute exercise bout, seven recreationally active men completed 4 h of cycle exercise at 55% peak oxygen consumption. Muscle samples were obtained before and at 10 min and 4 h of exercise for the measurement of PDH activity and the extraction of intact mitochondria for the measurements of PDK activity and PDK-2 and PDK-4 protein expression. Carbohydrate oxidation was reduced ( P < 0.05) with exercise duration. Muscle glycogen content was lower ( P ≤ 0.05) at 4 h compared with rest and there was no change in muscle pyruvate content from 10 to 240 min during exercise (10 min: 0.28 ± 0.05; 240 min: 0.35 ± 0.09 mmol/kg dry muscle). PDH activity increased ( P < 0.05) above resting values at 10 min (2.86 ± 0.26 mmol·min−1·kg wet muscle−1), but was lower than 10 min after 4 h (2.23 ± 0.24 mmol·min−1·kg wet muscle−1) of exercise. PDK-2 and PDK-4 protein expression was not different from rest at 10 min and 4 h of exercise. PDK activity at rest averaged 0.081 ± 0.016 min−1, was similar at 10 min, and increased ( P < 0.05) to 0.189 ± 0.013 min−1 at 4 h. Although reduced glycolytic flux may have played a role in decreasing carbohydrate oxidation, the results suggest that increased PDK activity contributed to the reduction in PDH activity and carbohydrate oxidation late in prolonged exercise. The increased PDK activity was independent of changes in intra-mitochondrial effectors, and PDK-2 and PDK-4 protein content, suggesting that it was caused by a change in the specific activity of the existing kinases.
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Affiliation(s)
- Matthew J Watt
- Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1.
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