Background: A signal transduction pathway is relatively signal-specific, but may become different in the study of regular training. The training-specific signal transduction pathways
(TSPs) in rat regular endurance training (RE) and their modulation with low level laser irradiation (LLLI) were investigated with quantitative difference (QD) in this study.
Methods:(1) The golden logarithm was defined as the logarithm to 0.618. The QD of two sets of data was defined as the absolute value of the golden logarithm of the ratio of their mean
values. The process logarithm (PL) of each group was the golden logarithm of the ratio of the early day data and the late day data, and its absolute value was called the resistance logarithm (RL). The
QD was significant or very significant if it is equal to or larger than a or b. The a/b of the cellular/molecular QD or the QD of PL/RL (PD/RD), the organ/tissue QD and the body QD were 0.80/1.27,
0.47/0.80 and 0.27/0.47, respectively. (2) Forty female Wistar rats (18 months old) were randomly divided into four groups: control-sedentary (C) group, RE group, LLLI-sedentary (L) group, and RE
group with pre-LLLI (LR). Trained rats performed an 8-week treadmill running. Each exercise session was carried out immediately after 30 s LLLI (810 nm, 200 mW/cm2, spot size 0.5 cm2) on the
gastrocnemius muscle. Insulin-like growth factor 1(IGF-1) protein and the messenger ribonucleic acid (mRNA) of peroxisome proliferator activated receptor-γ coactivator-1α (PGC-1α), nuclear repiratory
factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM) were determined by Western blot and reverse transcription and polymerase chain reaction (RT-PCR) 24 h after final treatment,
respectively. The data was analyzed with QD, PD and RD.
Results: (1) IGF-1/mTOR (mammalian Target Of Rapamycin) pathway is the TSP for regular strength training (sTSP) to increase the related skeletal muscle mass, and
AMPK(5'-adenosine-monophosphate-activated protein kinase)/PGC-1α pathway is the TSP for regular endurance training (eTSP) to increase the number of mitochondria in the related skeletal muscle. (2)
Gastrocnemius muscle mass, the muscle relative mass and IGF-1 were significantly increased in the LR group, but not in the L and RE groups, compared to sedentary group. (3) NRF-1 mRNA was very
significantly increased in the RE group, while significantly increased in the L and LR groups.
Conclusions: Training-specific signal transduction pathways may be activated in the regular training. The eTSP may be fully activated in the RE rats, and LLLI may further activate the
sTSP and its cross-talking with the fully activated eTSP in rats, which may play an important role in anti-aging.