AIM: To determine the adaptive changes in several molecules regulating muscle hypertrophy and atrophy after unloading, we examined whether unilateral lower limb suspension changes the mRNA and protein levels of SRF-linked (RhoA, RhoGDI, STARS and SRF), myostatin-linked (myostatin, Smad2, Smad3 and FLRG) and Foxo-linked (P-Akt, Foxo1, Foxo3a and Atrogin-1) mediators. METHODS: A single lower limb of each of eight healthy men was suspended for 20 days. Biopsy specimens were obtained from the vastus lateralis muscle pre- and post-suspension. RESULTS: The volume of the vastus lateralis muscle was significantly decreased after unloading. The amount of RhoA, RhoGDI or SRF protein in the muscle was not significantly changed post-suspension. An RT-PCR semiquantitative analysis showed increased levels of myostatin mRNA but not Smad2, Smad3 or FLRG mRNA. Unloading did not elicit significant changes in the amount of p-Smad3 or myostatin protein in the muscle. The amount of p-Akt protein was markedly reduced in the unloaded muscle. Lower limb SUSPENSION DID NOT INFLUENCE THE EXPRESSION PATTERN OF FOXO1, FOXO3A OR ATROGIN-1. CONCLUSION: Unloading inducing a mild degree of muscle atrophy may decrease p-Akt and increase myostatin but not SRF-linked mediators.
AIM: To determine the adaptive changes in several molecules regulating muscle hypertrophy and atrophy after unloading, we examined whether unilateral lower limb suspension changes the mRNA and protein levels of SRF-linked (RhoA, RhoGDI, STARS and SRF), myostatin-linked (myostatin, Smad2, Smad3 and FLRG) and Foxo-linked (P-Akt, Foxo1, Foxo3a and Atrogin-1) mediators. METHODS: A single lower limb of each of eight healthy men was suspended for 20 days. Biopsy specimens were obtained from the vastus lateralis muscle pre- and post-suspension. RESULTS: The volume of the vastus lateralis muscle was significantly decreased after unloading. The amount of RhoA, RhoGDI or SRF protein in the muscle was not significantly changed post-suspension. An RT-PCR semiquantitative analysis showed increased levels of myostatin mRNA but not Smad2, Smad3 or FLRG mRNA. Unloading did not elicit significant changes in the amount of p-Smad3 or myostatin protein in the muscle. The amount of p-Akt protein was markedly reduced in the unloaded muscle. Lower limb SUSPENSION DID NOT INFLUENCE THE EXPRESSION PATTERN OF FOXO1, FOXO3A OR ATROGIN-1. CONCLUSION: Unloading inducing a mild degree of muscle atrophy may decrease p-Akt and increase myostatin but not SRF-linked mediators.
Authors: Marita A Wallace; M Benjamin Hock; Bethany C Hazen; Anastasia Kralli; Rod J Snow; Aaron P Russell Journal: J Physiol Date: 2011-02-21 Impact factor: 5.182
Authors: C J Malavaki; G K Sakkas; G I Mitrou; A Kalyva; I Stefanidis; K H Myburgh; C Karatzaferi Journal: J Muscle Res Cell Motil Date: 2016-01-04 Impact factor: 2.698