Difference between revisions of "Sheldon 2015 Abstract MiPschool Greenville 2015"

Latest revision as of 16:02, 13 November 2017

eNOS is required to preserve hepatic mitochondrial function in western diet-induced nonalcoholic fatty liver disease.

Link:

Sheldon RD, Linden MA, Morris EM, Meers GM, Laughlin MH, Rector RS (2015)

Event: MiPschool Greenville 2015

Endothelial nitric oxide synthase (eNOS) produces physiological concentrations of nitric oxide that can influence mitochondrial biogenesis and electron transport chain activity. Hepatic mitochondrial dysfunction is a hallmark feature of nonalcoholic fatty liver disease (NAFLD), yet the underlying mechanisms of this phenomenon remain elusive. Here, we tested the hypothesis that eNOS is required for proper hepatic mitochondrial function in NAFLD. Wild-type (WT) and eNOS knockout (eNOS-/-) mice received either control (CON; 10% fat, 3.5% sucrose) or a western diet high in fat (45%), sucrose (17%) and cholesterol (1%; HFC) for 18-weeks. HFC diet feeding induced histological NAFLD and increased weight gain and % body fat in both genotypes compared to CON diet. Complete hepatic mitochondrial palmitate oxidation to CO₂ was elevated in both eNOS-/- groups compared with WT mice (p<0.05), while incomplete acid-soluble metabolite production was elevated only in eNOS-/--CON compared to other groups. In addition, maximal FCCP-uncoupled mitochondrial respiration tended to be elevated in eNOS-/--CON compared to WT-CON (+24%; p=0.08) but was significantly reduced with HFC feeding in eNOS-/- mice (-37% vs eNOS-/--CON; p<0.05). Finally, HFC feeding dramatically reduced hepatic mRNA expression of the putative control marker for mitochondrial biogenesis, PGC-1α, in WT (-30%) and eNOS-/- (-60%) compared with WT-CON (p<0.05). These data suggest that eNOS-/- mice are more susceptible to Western diet-induced hepatic mitochondrial dysfunction that may be related to an impaired capacity to generate new, healthy mitochondria.

• O2k-Network Lab: US MO Columbia Rector RS

Labels: MiParea: Respiration, mt-Biogenesis;mt-density, Exercise physiology;nutrition;life style

Organism: Mouse Tissue;cell: Liver

Coupling state: LEAK, OXPHOS, ET Pathway: N, NS HRR: Oxygraph-2k Event: Oral

Affiliations

Harry S Truman Memorial Veterans Med Center and Univ Missouri, Columbia, MO, USA - [email protected]

Figures

MiPschool2015Greenville Sheldon Figure1.jpg

Figure 1. Functional measures of isolated hepatic mitochondria. *; Main effect of diet. #; Main effect of genotype. %; significant interaction, eNOS-/--HFC different from WT-HFC. $; significant interaction, eNOS-/--CON different from eNOS-/--HFC.

MiPschool2015Greenville Sheldon Figure2.jpg

Figure 2. Markers of mitochondrial biogenesis in whole liver homogenate. *; Main effect of diet. #; Main effect of genotype. %; significant interaction, eNOS-/--HFC different from WT-HFC. $; significant interaction, eNOS-/--CON different from eNOS-/--HFC.

Support

Supported by: HL036088 (MHL) and VHA-CDA2 1299-03(RSR)

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 {{Abstract
-|title=Twelve weeks of treadmill training as a treatment for western diet induced NASH alters mitochondrial respiration in hyperphagic OLETF rats.
+|title=eNOS is required to preserve hepatic mitochondrial function in western diet-induced nonalcoholic fatty liver disease.
 |authors=Sheldon RD, Linden MA, Morris EM, Meers GM, Laughlin MH, Rector RS
 |year=2015
 |event=MiPschool Greenville 2015
-|abstract=Impairments in mitochondrial function are implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and the progression to nonalcoholic steatohepatitis (NASH; hepatic inflammation and fibrosis). Lifestyle interventions (diet and exercise) are among the most effective preventative measures against NAFLD, yet less is known about the propensity for exercise training to reverse established NASH. Here we tested the hypothesis that initiation of treadmill exercise training in early NASH would improve hepatic mitochondrial respiration in rats. Hyperphagic OLETF (Otsuka Long-Evans Tokushima Fatty) rats were fed a western-style diet (WD; 45% fat, 1% cholesterol, 17% sucrose) for 24-weeks. Following 12-weeks of WD, OLETF rats were randomly divided into sedentary control (SED), endurance treadmill exercise training (EX), and food restriction (FR; ~85%, to account for reduced food intake that occurs with exercise ) groups for an additional 12-weeks. Isolated hepatic mitochondrial state II and state III  respiration were assessed using Clark electrodes in response to stimulation with  glutamate (G; 10 mM), malate (M; 1 mM), succinate (S; 10 mM) and/or ADP (0.2 mM). Maximal uncoupled respiration was determined via 2 µM serial additions of FCCP.  FR resulted in elevated state III respiration through complex I (G+M; +36%) and complex I&II (G+M+S; +39%) and maximal uncoupled respiration (+FCCP; +29%) when compared to the EX group (''p'' < 0.05) while no changes were observes versus SED. Surprisingly, State III respiration through complex I&II (G+M+S) was significantly reduced (-23%; ''p'' < 0.05) in EX versus SED rats. Finally, EX caused an increase (~10%) versus SED (''p''=) and FR in whole liver citrate synthase activity, suggesting that EX increases mitochondrial content. These data indicate that 12-weeks of treadmill exercise training with ongoing WD feeding are ineffective at improving and may further impair mitochondrial respiration in this model of NASH. Alternatively, the modest increase hepatic mitochondrial content may indicate a reduced functional need per unit of mitochondria. Future studies should address whether a synergism exists between a healthful diet and exercise training when used as a treatment paradigm for NASH.
+|abstract=Endothelial nitric oxide synthase (eNOS) produces physiological concentrations of nitric oxide that can influence mitochondrial biogenesis and electron transport chain activity. Hepatic mitochondrial dysfunction is a hallmark feature of nonalcoholic fatty liver disease (NAFLD), yet the underlying mechanisms of this phenomenon remain elusive. Here, we tested the hypothesis that eNOS is required for proper hepatic mitochondrial function in NAFLD. Wild-type (WT) and eNOS knockout (eNOS-/-) mice received either control (CON; 10% fat, 3.5% sucrose) or a western diet high in fat (45%), sucrose (17%) and cholesterol (1%; HFC) for 18-weeks. HFC diet feeding induced histological NAFLD and increased weight gain and % body fat in both genotypes compared to CON diet. Complete hepatic mitochondrial palmitate oxidation to CO<sub>2</sub> was elevated in both eNOS-/- groups compared with WT mice (''p''<0.05), while incomplete acid-soluble metabolite production was elevated only in eNOS-/--CON compared to other groups. In addition, maximal FCCP-uncoupled mitochondrial respiration tended to be elevated in eNOS-/--CON compared to WT-CON (+24%; p=0.08) but was significantly reduced with HFC feeding in eNOS-/- mice (-37% vs eNOS-/--CON; ''p''<0.05).  Finally, HFC feeding dramatically reduced hepatic mRNA expression of the putative control marker for mitochondrial biogenesis, PGC-1α, in WT (-30%) and eNOS-/- (-60%) compared with WT-CON (''p''<0.05). These data suggest that eNOS-/- mice are more susceptible to Western diet-induced hepatic mitochondrial dysfunction that may be related to an impaired capacity to generate new, healthy mitochondria.
 |mipnetlab=US MO Columbia Rector RS
 }}
 {{Labeling
-|area=Respiration, Exercise physiology;nutrition;life style
+|area=Respiration, mt-Biogenesis;mt-density, Exercise physiology;nutrition;life style
-|organism=Rat
+|organism=Mouse
-|preparations=Isolated mitochondria
+|tissues=Liver
-|couplingstates=LEAK, OXPHOS, ETS
+|couplingstates=LEAK, OXPHOS, ET
-|substratestates=CI, CIII
+|pathways=N, NS
 |instruments=Oxygraph-2k
+|event=Oral
 }}
 == Affiliations ==
--Dept Nutrition and Exercise Physiol; 2-Dept Medicine; 3-Dept Biomed Sci, Univ Missouri; 4-Harry S Truman Memorial VA Hospital, Columbia, MO, USA. - [email protected]
+Harry S Truman Memorial Veterans Med Center and Univ Missouri, Columbia, MO, USA - [email protected]
-== Figure 1 ==
+== Figures ==
-[[Image:MiPschool2015Greenville Sheldon Figure.jpg|left|600px]] Figure 1. (A) Oxygen consumption rate in isolated hepatic mitochondria. (B) Citrate synthase activity in whole liver homogenate. *; EX different from FR, ''p'' < 0.05. #; EX different from SED, ''p'' < 0.05.
+[[Image:MiPschool2015Greenville Sheldon Figure1.jpg|left|600px]] Figure 1. Functional measures of isolated hepatic mitochondria. *; Main effect of diet. #; Main effect of genotype. %; significant interaction, eNOS-/--HFC different from WT-HFC. $; significant interaction, eNOS-/--CON different from eNOS-/--HFC.
+[[Image:MiPschool2015Greenville Sheldon Figure2.jpg|right|600px]] Figure 2. Markers of mitochondrial biogenesis in whole liver homogenate. *; Main effect of diet. #; Main effect of genotype. %; significant interaction, eNOS-/--HFC different from WT-HFC. $; significant interaction, eNOS-/--CON different from eNOS-/--HFC.
+== Support ==
+Supported by: HL036088 (MHL) and VHA-CDA2 1299-03(RSR)