Difference between revisions of "George 2015 Abstract MiPschool Cape Town 2015"
| Line 5: | Line 5: | ||
|event=MiPschool Cape Town 2015 | |event=MiPschool Cape Town 2015 | ||
|abstract=Excess fructose consumption has been shown to mediate mitochondrial | |abstract=Excess fructose consumption has been shown to mediate mitochondrial | ||
- | β-oxidation dysfunction in skeletal muscle, resulting in decreased fattyacid | ||
mediated respiration and elevated levels of long chain acylcarnitine | mediated respiration and elevated levels of long chain acylcarnitine | ||
intermediates [1]. It has been observed that fructose decreases the | intermediates [1]. It has been observed that fructose decreases the | ||
expression of LCAD (long chain acyl-CoA dehydrogenase) [2], the rate | expression of LCAD (long chain acyl-CoA dehydrogenase) [2], the rate | ||
limiting enzyme in | limiting enzyme in β-oxidation, and of SIRT3 (the NAD+-dependent | ||
deacetylase that regulates the activity of LCAD) [1]. Regular exercise | deacetylase that regulates the activity of LCAD) [1]. Regular exercise | ||
has been shown to restore mitochondrial function, including | has been shown to restore mitochondrial function, including β-oxidation, | ||
and improve insulin sensitivity in type-2 diabetics. Studies in mice and | and improve insulin sensitivity in type-2 diabetics. Studies in mice and | ||
rats have found that exercise increases NAD+ levels (3), SIRT3 levels | rats have found that exercise increases NAD+ levels (3), SIRT3 levels | ||
(4) and fatty acid oxidation (5). These observations suggest that a) the | (4) and fatty acid oxidation (5). These observations suggest that a) the | ||
fructose-induced dysfunction in | fructose-induced dysfunction in β-oxidation might be due to its effect | ||
on the NADH/NAD+ ratio in cells and b) a program of exercise might | on the NADH/NAD+ ratio in cells and b) a program of exercise might | ||
ameliorate the effects of fructose on | ameliorate the effects of fructose on β-oxidation. Therefore, the proposed study aims to test the following hypotheses: a) Fructose-induced | ||
decline in LCAD and SIRT3 activities results from decreased NAD+ | decline in LCAD and SIRT3 activities results from decreased NAD+ | ||
levels. b) Regular exercise will ameliorate fructose-induced | levels. b) Regular exercise will ameliorate fructose-induced β-oxidation | ||
dysfunction in skeletal muscle by augmenting LCAD and SIRT3 activities | dysfunction in skeletal muscle by augmenting LCAD and SIRT3 activities | ||
as well as NAD+ content. c) Improvements in | as well as NAD+ content. c) Improvements in β-oxidation, SIRT3 activity | ||
and LCAD function by exercise result from increased NAD+ levels in | and LCAD function by exercise result from increased NAD+ levels in | ||
cells. A rat model will be used to test these hypotheses. Rats will be | cells. A rat model will be used to test these hypotheses. Rats will be | ||
| Line 32: | Line 32: | ||
abdominal fat weight, b) plasma free fatty acids, insulin, and glucose | abdominal fat weight, b) plasma free fatty acids, insulin, and glucose | ||
levels, c) acylcarnitine levels in blood and skeletal muscle by ESI-MS/ | levels, c) acylcarnitine levels in blood and skeletal muscle by ESI-MS/ | ||
MS, and d) mitochondrial | MS, and d) mitochondrial β-oxidation in permeabilized skeletal muscle | ||
fibres using high-resolution respirometry with long chain acylcarnitines | fibres using high-resolution respirometry with long chain acylcarnitines | ||
+ malate as substrates. In addition, the activities and/or levels of LCAD, | + malate as substrates. In addition, the activities and/or levels of LCAD, | ||
Revision as of 14:55, 20 March 2015
| Regulation of LCAD and SIRT3 activities by NAD+ in skeletal muscle of fructose-fed rats. |
Link:
Event: MiPschool Cape Town 2015
Excess fructose consumption has been shown to mediate mitochondrial β-oxidation dysfunction in skeletal muscle, resulting in decreased fattyacid mediated respiration and elevated levels of long chain acylcarnitine intermediates [1]. It has been observed that fructose decreases the expression of LCAD (long chain acyl-CoA dehydrogenase) [2], the rate limiting enzyme in β-oxidation, and of SIRT3 (the NAD+-dependent deacetylase that regulates the activity of LCAD) [1]. Regular exercise has been shown to restore mitochondrial function, including β-oxidation, and improve insulin sensitivity in type-2 diabetics. Studies in mice and rats have found that exercise increases NAD+ levels (3), SIRT3 levels (4) and fatty acid oxidation (5). These observations suggest that a) the fructose-induced dysfunction in β-oxidation might be due to its effect on the NADH/NAD+ ratio in cells and b) a program of exercise might ameliorate the effects of fructose on β-oxidation. Therefore, the proposed study aims to test the following hypotheses: a) Fructose-induced decline in LCAD and SIRT3 activities results from decreased NAD+ levels. b) Regular exercise will ameliorate fructose-induced β-oxidation dysfunction in skeletal muscle by augmenting LCAD and SIRT3 activities as well as NAD+ content. c) Improvements in β-oxidation, SIRT3 activity and LCAD function by exercise result from increased NAD+ levels in cells. A rat model will be used to test these hypotheses. Rats will be randomly placed in one of the following treatment groups for 8 weeks: a) no treatment (control), b) 10% fructose water, c) 10% fructose + nicotidamide ribosome (an NAD+-boosting agent), d) 10% fructose + exercise, e) 10% fructose + exercise + FK866 (an inhibitor of the NAD+ salvage pathway) f) exercise, g) 10% glucose. All rats will receive chow and water ad libitum. The following parameters will be measured: a) abdominal fat weight, b) plasma free fatty acids, insulin, and glucose levels, c) acylcarnitine levels in blood and skeletal muscle by ESI-MS/ MS, and d) mitochondrial β-oxidation in permeabilized skeletal muscle fibres using high-resolution respirometry with long chain acylcarnitines + malate as substrates. In addition, the activities and/or levels of LCAD, SIRT3, Citrate Synthase and NADH/NAD+ will be measured.
• O2k-Network Lab: ZA Cape Town Ojuka EO
Labels: MiParea: Exercise physiology;nutrition;life style
Organism: Rat
Tissue;cell: Skeletal muscle
Preparation: Permeabilized tissue
HRR: Oxygraph-2k
Affiliations
UCT/MRC Research Unit Exercise Sc & Sports Medicine, Dept Human Biol Univ Cape Town, Sport Science, South Africa. - GRGSID001@myuct.ac.za
