Ma. Griffiths et al., EXERCISE DOWN-REGULATES HEPATIC LIPOGENIC ENZYMES IN FOOD-DEPRIVED AND REFED RATS, The Journal of nutrition, 126(8), 1996, pp. 1959-1971
The effects of an acute bout of prolonged exercise on the activities o
f several hepatic lipogenic enzymes and the abundance of fatty acid sy
nthase (FAS) mRNA were evaluated using a food deprivation-refeeding pr
otocol in which diets contained 50% of the energy from either fructose
or cornstarch. Food was withheld from male rats for 48 h and refed fo
r 0, 4, 8, 12, 24 or 48 h. At each time point, half of each dietary gr
oup was subjected to a single bout of treadmill running until exhausti
on and killed immediately. The other half of each group rested without
food for the same amount of time before being killed. Exercise signif
icantly decreased FAS activity by 57, 46, 10, 26 and 70% at 4, 8, 12,
24 and 48 h of refeeding, respectively, in the fructose-fed rats; and
by 70 and 63% at 24 and 48 h of refeeding, respectively, in the cornst
arch-fed rats. Activities of L-type pyruvate kinase and glucose 6-phos
phate dehydrogenase were significantly decreased after exercise in the
fructose-fed,bu starch-fed rats. In rested rats, FAS mRNA abundance i
ncreased similar to fourfold above the unfed levels after 8 and 12 h o
f refeeding. Exercise attenuated the diet-induced increases in FAS mRN
A abundance. At 8 h of refeeding, both cornstarch- and fructose-fed ex
ercised rats had 71% (P < 0.05) of the FAS mRNA levels of their rested
counterparts; at 12 h, these exercised rats showed only 46 and 27% (P
< 0.05) of FAS mRNA levels compared with rested rats fed the same die
t. We conclude that dietary induction of FAS activity and mRNA abundan
ce can be inhibited by prolonged exercise, suggesting that exercise ma
y influence FAS transcription and/or mRNA stability.