Induction of human skeletal muscle lipoprotein lipase gene
expression by short term exercise is transient.
Seip, Richard L., Ken Mair, Thomas G. Cole, and Clay F. Semenkovich.
Departments of Medicine and Cell Biology & Physiology,
Washington University School of Medicine, St. Louis, MO 63110
APStracts 3:0207E, 1996.
Exercise increases skeletal muscle lipoprotein lipase (LPL)
expression, but the time course of this response is not known. In the
present study, we examined the time course of the LPL response to
both short term and acute exercise, and measured circulating levels
of putative regulators of muscle LPL. Nine adults underwent short
term exercise training (60-90 min of stationary cycling at 55-70% of
leg ergometer VO2 peak on five consecutive days). Five vastus
lateralis biopsies were performed: before training, 20 h after the
fourth bout (immediately before the fifth bout), and 0.2, 4, and 8 h
after the fifth bout. After four bouts of exercise in four days,
there was no increase in LPL mass or LPL mRNA exactly 20 h after the
fourth bout. However, when tissues were sampled closer to the
exercise bout on the fifth day, transient increases were seen. On Day
5, LPL mRNA increased by 127% (p < 0.05) at 4 h post-exercise
which was followed by an increase in LPL mass of 93% (p <
0.05) at 8 h post-exercise. Serum triglycerides decreased by 23% (p
< 0.05) during the protocol. Two nonexercising subjects showed
no consistent change in LPL mRNA or mass. Acute exercise transiently
increased levels of norepinephrine (nine-fold) and epinephrine (five
-fold), and reduced insulin levels. Acute exercise preceded by four
daily bouts of exercise induces a transient rise in LPL mRNA followed
by rise in LPL mass, suggesting that these responses are temporally
related. This induction of LPL gene expression may result from
dynamic changes in serum catecholamines, plasma insulin, or events
intrinsic to muscle contraction itself.
Received 29 March 1996; accepted in final form 30 September 1996.
APS Manuscript Number E155-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996