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A RAPID UP-REGULATION IN UCP3 TRANSCRIPTIONAL ACTIVITY IN RESPONSE
TO MODERATE INTENSITY EXERCISE IN RAT SKELETAL MUSCLE
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Keiko
Kusuhara1
, Takashi Tobe2, Takaharu Negoro2 and Takashi Abe1 |
1Tokyo Metropolitan University, Department of exercise and sport science,
1-1, Minami-Osawa, Hachioji, Tokyo, Japan
2Showa University, Department of medicine information, 1-5-8,
Hatanodai, Shinagawa-ku, Tokyo, Japan
| Received |
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18 February 2005 |
| Accepted |
|
25
April 2005 |
| Published |
|
01
June 2005 |
©
Journal of Sports Science and Medicine (2005) 4, 170 - 178
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| ABSTRACT |
| Uncoupling
protein 3 (UPC3) is a candidate protein transporter that uncouples
oxidative phosphorylation of mitochondrial respiration in skeletal
muscle. A number of studies on UCP3 functions under various physiological
conditions have suggested that the function of UCP3 is not limited
only to regulation of whole-body energy metabolism but is also involved
in regulation of substrate (lipids and glucose) metabolism. The purpose
of the present study was to clarify the time course of UCP3 mRNA expression
in rat skeletal muscle during a 1 h bout of treadmill exercise and
to examine whether changes in fat/glucose metabolism modulates UCP3
mRNA expression. The pattern of UCP3 mRNA expression during the exercise
was biphasic in both the soleus and gastrocnemius muscles. UCP3 expression
increased at 5 min of exercise (soleus: 232%, p < 0.05, gastrocnemius:
185%, p < 0.05, respectively), and at the end of the exercise (196%,
p < 0.05 and 193%, p < 0.05, respectively). UCP3 mRNA expression
was still increased at 3 h post-exercise in both muscles, 200% (p
< 0.05) and 237% (p < 0.05), respectively. However, at 20 min
of the exercise, UCP3 mRNA expression was similar to control levels
in both muscles (104% and 97%, respectively). The time course of plasma
free fatty acid (FFA) did not follow the same time course as UCP3
mRNA expression. Plasma FFA peaked at the end of the exercise, suggesting
that FFA did not play a role in inducing UCP3 mRNA expression. Glucose
transporter 4 (GLUT4) mRNA expression did not change during or after
exercise. These data indicated a rapid acceleration in UCP3's transcription
activity in response to exercise, and suggest that potential factor(s)
other than changes in fat/glucose metabolism regulate UCP3 gene expression
during moderate exercise.
KEY
WORDS: UCP3, FFA, GLUT4, exercise.
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