Short-term strength training and the expression of myostatin and IGF-I isoforms in rat muscle and tendon: differential effects of specific contraction types
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Short-term strength training and the expression of myostatin and IGF-I isoforms in rat muscle and tendon : differential effects of specific contraction types. / Heinemeier, K M; Olesen, J L; Schjerling, P; Haddad, F; Langberg, Henning; Baldwin, K M; Kjaer, M.
I: Journal of Applied Physiology, Bind 102, Nr. 2, 2007, s. 573-81.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Short-term strength training and the expression of myostatin and IGF-I isoforms in rat muscle and tendon
T2 - differential effects of specific contraction types
AU - Heinemeier, K M
AU - Olesen, J L
AU - Schjerling, P
AU - Haddad, F
AU - Langberg, Henning
AU - Baldwin, K M
AU - Kjaer, M
PY - 2007
Y1 - 2007
N2 - In skeletal muscle, an increased expression of insulin like growth factor-I isoforms IGF-IEa and mechano-growth factor (MGF) combined with downregulation of myostatin is thought to be essential for training-induced hypertrophy. However, the specific effects of different contraction types on regulation of these factors in muscle are still unclear, and in tendon the functions of myostatin, IGF-IEa, and MGF in relation to training are unknown. Female Sprague-Dawley rats were subjected to 4 days of concentric, eccentric, or isometric training (n = 7-9 per group) of the medial gastrocnemius, by stimulation of the sciatic nerve during general anesthesia. mRNA levels for myostatin, IGF-IEa, and MGF in muscle and Achilles' tendon were measured by real-time RT-PCR. Muscle myostatin mRNA decreased in response to all types of training (2- to 8-fold) (P <0.05), but the effect of eccentric training was greater than concentric and isometric training (P <0.05). In tendon, myostatin mRNA was detected, but no changes were seen after exercise. IGF-IEa and MGF increased in muscle (up to 15-fold) and tendon (up to 4-fold) in response to training (P <0.01). In tendon no difference was seen between training types, but in muscle the effect of eccentric training was greater than concentric training for both IGF-IEa and MGF (P <0.05), and for IGF-IEa isometric training had greater effect than concentric (P <0.05). The results indicate a possible role for IGF-IEa and MGF in adaptation of tendon to training, and the combined changes in myostatin and IGF-IEa/MGF expression could explain the important effect of eccentric actions for muscle hypertrophy.
AB - In skeletal muscle, an increased expression of insulin like growth factor-I isoforms IGF-IEa and mechano-growth factor (MGF) combined with downregulation of myostatin is thought to be essential for training-induced hypertrophy. However, the specific effects of different contraction types on regulation of these factors in muscle are still unclear, and in tendon the functions of myostatin, IGF-IEa, and MGF in relation to training are unknown. Female Sprague-Dawley rats were subjected to 4 days of concentric, eccentric, or isometric training (n = 7-9 per group) of the medial gastrocnemius, by stimulation of the sciatic nerve during general anesthesia. mRNA levels for myostatin, IGF-IEa, and MGF in muscle and Achilles' tendon were measured by real-time RT-PCR. Muscle myostatin mRNA decreased in response to all types of training (2- to 8-fold) (P <0.05), but the effect of eccentric training was greater than concentric and isometric training (P <0.05). In tendon, myostatin mRNA was detected, but no changes were seen after exercise. IGF-IEa and MGF increased in muscle (up to 15-fold) and tendon (up to 4-fold) in response to training (P <0.01). In tendon no difference was seen between training types, but in muscle the effect of eccentric training was greater than concentric training for both IGF-IEa and MGF (P <0.05), and for IGF-IEa isometric training had greater effect than concentric (P <0.05). The results indicate a possible role for IGF-IEa and MGF in adaptation of tendon to training, and the combined changes in myostatin and IGF-IEa/MGF expression could explain the important effect of eccentric actions for muscle hypertrophy.
KW - Animals
KW - Female
KW - Gene Expression Regulation
KW - Hypertrophy
KW - Insulin-Like Growth Factor I
KW - Isometric Contraction
KW - Muscle Contraction
KW - Muscle, Skeletal
KW - Myostatin
KW - Physical Conditioning, Animal
KW - Protein Isoforms
KW - RNA, Messenger
KW - Random Allocation
KW - Rats
KW - Rats, Sprague-Dawley
KW - Tendons
KW - Transforming Growth Factor beta
U2 - 10.1152/japplphysiol.00866.2006
DO - 10.1152/japplphysiol.00866.2006
M3 - Journal article
C2 - 17038487
VL - 102
SP - 573
EP - 581
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 2
ER -
ID: 38366095