Akt-dependent and Akt-independent pathways are involved in protein synthesis activation during reloading of disused soleus muscle.

INTRODUCTION

The purpose of our study was to assess the contribution of insulin growth factor-1-dependent and phosphatidic acid-dependent signaling pathways to activation of protein synthesis (PS) in rat soleus muscle during early recovery from unloading.

METHODS

Wistar rats were divided into: Control, 14HS [14-day hindlimb suspension (HS)], 3R+placebo (3-day reloading + saline administration), 3R+Wort (3-day reloading + wortmannin administration), 3R+But (3-day reloading + 1-butanol administration). SUnSET and Western blot analyses were used in this study.

RESULTS

Wortmannin and 1-butanol induced a decrease in protein kinase B (phospho-Akt) and the rate of PS (P < 0.05) versus Control. In 3R+placebo and 3R+Wort, phosphorylation of glycogen synthase kinase 3 beta (phospho-GSK-3β) was increased versus Control (P < 0.05). Wortmannin administration during reloading did not alter phospho-p70S6K (70 kDa ribosomal protein S6 kinase) versus 3R+placebo. In 3R+But, there was a decline in phospho-GSK-3β versus 3R+placebo and Control. In 3R+But, there was a decrease in phopho-p70S6K (P < 0.05) versus 3R+placebo.

CONCLUSIONS

These results suggest that PS activation during 3-day reloading following 14HS involves both Akt-dependent and Akt-independent pathways. Muscle Nerve 55: 393-399, 2017.