TY - JOUR
T1 - Short- and long-term swimming exercise training increases myocardial insulin-like growth factor-I gene expression
AU - Scheinowitz, M.
AU - Kessler-Icekson, G.
AU - Freimann, S.
AU - Zimmermann, R.
AU - Schaper, W.
AU - Golomb, E.
AU - Savion, N.
AU - Eldar, M.
N1 - Funding Information:
This work was performed as partial fulfillment of the requirements for a M.Sc. degree of S. Freimann, Sackler Faculty of Medicine, Tel-Aviv University. We thank Pharmacia AB, Sweden, for providing us with human recombinant IGF-I. The authors also thank P. Strauch for technical assistance and to Prof. Z. Laron for reviewing the manuscript. This work was supported by the German-Israeli-Foundation (GIF Contract #I 0401-266.02/94, grantee R.Z., M.E., and M.S.).
PY - 2003/2
Y1 - 2003/2
N2 - Objectives. We investigated the effect of short- and long-term swimming exercise, with or without insulin-like growth factor (IGF)-I administration, on the expression of myocardial IGFs and contractile proteins. Methods. Sprague-Dawley male rats (n = 36) were subjected to swimming exercise for 2 or 6 weeks. IGF-I (0.5 mg/rat) was administered continuously for 1 week, using alzet osmotic pumps. Control groups remained sedentary. IGF-I, IGF-I receptor (IGF-IR), IGF-II, skeletal α-actin (sk-actin), and β myosin heavy chain (βMHC) mRNAs were measured using Northern blot analysis and RT-PCR. Results. A significant 2-fold increase in myocardial IGF-I mRNA was found after 2 and 6weeks of swimming in both IGF-I treated and untreated rats (p < 0.001). IGF-IR mRNA was significantly (p < 0.05) increased after 6 weeks of training only in the IGF-I treated animals. IGF-II mRNA remained unchanged at all time points. While βMHC mRNA was significantly decreased (p = 0.003) at 2 and 6 weeks, sk-actin mRNA remained unchanged. Conclusions. Short- and long-term swimming exercise training increase myocardial expression of IGF-I mRNA. Exogenous administration of IGF-I, during the first week of the exercise session, did not produce any effect on myocardial IGF-I but was associated with increased IGF-IR signal after the long-term exercise training. These data suggest a relationship between IGF-I expression and cardiac adaptation to exercise training.
AB - Objectives. We investigated the effect of short- and long-term swimming exercise, with or without insulin-like growth factor (IGF)-I administration, on the expression of myocardial IGFs and contractile proteins. Methods. Sprague-Dawley male rats (n = 36) were subjected to swimming exercise for 2 or 6 weeks. IGF-I (0.5 mg/rat) was administered continuously for 1 week, using alzet osmotic pumps. Control groups remained sedentary. IGF-I, IGF-I receptor (IGF-IR), IGF-II, skeletal α-actin (sk-actin), and β myosin heavy chain (βMHC) mRNAs were measured using Northern blot analysis and RT-PCR. Results. A significant 2-fold increase in myocardial IGF-I mRNA was found after 2 and 6weeks of swimming in both IGF-I treated and untreated rats (p < 0.001). IGF-IR mRNA was significantly (p < 0.05) increased after 6 weeks of training only in the IGF-I treated animals. IGF-II mRNA remained unchanged at all time points. While βMHC mRNA was significantly decreased (p = 0.003) at 2 and 6 weeks, sk-actin mRNA remained unchanged. Conclusions. Short- and long-term swimming exercise training increase myocardial expression of IGF-I mRNA. Exogenous administration of IGF-I, during the first week of the exercise session, did not produce any effect on myocardial IGF-I but was associated with increased IGF-IR signal after the long-term exercise training. These data suggest a relationship between IGF-I expression and cardiac adaptation to exercise training.
KW - IGF-I
KW - IGF-I receptors
KW - IGF-II
KW - Myocardial contractile proteins
UR - http://www.scopus.com/inward/record.url?scp=0037292011&partnerID=8YFLogxK
U2 - 10.1016/S1096-6374(02)00137-5
DO - 10.1016/S1096-6374(02)00137-5
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AN - SCOPUS:0037292011
SN - 1096-6374
VL - 13
SP - 19
EP - 25
JO - Growth Hormone and IGF Research
JF - Growth Hormone and IGF Research
IS - 1
ER -