Transforming growth factor-beta in the brain is activated by exercise and increases mobilization of fat-related energy substrates in rats.
We have recently reported that inhibition of transforming growth factor (TGF)-beta in the brain reduced fat-related energy substrates concentrations in response to exercise. We investigated the relevance between the mobilization of fat-related energy substrates (nonesterified fatty acid and ketone bodies) during exercise and the effects of TGF-beta in the brain. Low-intensity exercise was simulated by contraction of the hindlimbs, induced by electrical stimulation at 2 Hz in anesthetized rats (Sim-Ex). As with actual exercise, it was confirmed that mobilization of carbohydrate-related energy substrates (glucose and lactic acid) occurred immediately after the onset of Sim-Ex, and mobilization of fat-related energy substrates followed thereafter. The timing of mobilization of fat-related substrates corresponded to that of the increase in TGF-beta in cerebrospinal fluid (CSF) in Sim-Ex. The level of TGF-beta in CSF significantly increased after 10 min of Sim-Ex and remained elevated until 30 min of Sim-Ex. Intracisternal administration of TGF-beta caused rapid mobilization of fat-related energy substrates. Meanwhile, there were no effects on the changes in carbohydrate-related substrates. The levels of catecholamines were slightly elevated after TGF-beta administration, and, although not significantly in statistical terms, we consider that at least a part of TGF-beta signal was transducted via the sympathetic nervous system because of these increases. These data indicate that TGF-beta in the brain is closely related to the mobilization of fat-related energy substrates during low-intensity exercise. We hypothesized that the central nervous system plays a role in the regulation of energy metabolism during low-intensity exercise and this may be mediated by TGF-beta.
Shibakusa
Tetsuro
T
Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto Univ, Kitashirakawa, Sakyo, Kyoto, Japan.
Mizunoya
Wataru
W
Okabe
Yuki
Y
Matsumura
Shigenobu
S
Iwaki
Yoko
Y
Okuno
Alato
A
Shibata
Katsumi
K
Inoue
Kazuo
K
Fushiki
Tohru
T
D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D007657:Ketone Bodies / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D002395:Catecholamines; D005230:Fatty Acids, Nonesterified; D007657:Ketone Bodies; D016212:Transforming Growth Factor beta; D019344:Lactic Acid; D005947:Glucose