Experimental Study On The Effect Of IGF-1 On The Apoptosis Of Skeletal Muscle Of Rats After Taking Exhausting Exerxises

Objective To investigate the phenomenon of apoptosis in rats' muscle and the effect of IGF-1 (Insulin-like growth factor-1) on skeletal muscles in rats which taking repeated exhausting run on the treadmill.Methods Using SD rat repeat exhausting and IGF-1 effect model. 40 SD male rats were divided randomly into four groups: queit control group(A),normal train group(C), exhausting exercising control group(S), exhausting exercising and IGF-1 effect group(Y). The exercising groups(S and Y group) took repeating exhausting run on the treadmill for 1 weeks. The C group took normal training for 1 week.Inspect the exercise length ,and the content of free calcium of sarcoplasmic reticulum and mitochondria, the activity of Ca2+-ATPase in rats' musculi skeleti cell membrane,sarcoplasmic reticulum and mitochondria. Observe the changes of the skeletal muscle cells and mitochondria ultrastructure through the electron microscope(TEM). Apoptotic cells of gastrocnemius muscle cells of rats were measured by TUNEL dyeing and Flow cytometer(FCM). The express of the mRNA of GULT4 and apoptosis-correlating genes were detected by means of polymerase chain reaction(PCR).Investigated the possible mechanism of IGF-I inhibiting cell apoptosis,promoting cell survival and enhance locomotivity.Results The locomotivity and total exercise treadmill length of Y group is significant higher than S group after having 1-week exhausting exercise on treadmill, P<0.05. Y and C groups' Ca2+-ATPase activity and free calcium content of mitochondria were less than the S and A group, P< 0.05. Y and C groups' activity of Ca2+-ATPase of cellular mimbrane and free calcium content of sarcoplasmic were more than the S and A group, P< 0.05. Skeletal muscle myofilament disord, the contraction of nucleus and thevacuolar degeneration and engorge of mitochondria could be seen under electron microscope(TEM) in S group, the number of mitochondria and glycogenosome is higher in C and Y group. The number of apoptosis cell in C group is more than Y and C group by TUNEL dyeingand FCM , P< 0.05 .The expresses of mRNA of GULT4 were powerful in the Y and C group. In the Y and C groups, the expresses of bcl-2 increased more than in S group, the expresses of Bax is crosscurrent.Conclusions A low level of Ca2+-ATPase activity was observed in the working skeletal muscle cellular menbrane and sarcoplasmic reticulum which have taken 1 weeks repeated centrifugal contraction.but it was anomaly higher in mitochondria.that lead to the functional disturbance of mitochondria. The malfunction of the mitochondria maybe the main reason of induce the apoptosis of muscle cells. The IGF-I can promote the express of the mRNA of GULT4 and the energy metabolism of mitochondrial.enhance the activity of Ca2+-ATPase in cell membrane and sarcoplasmic reticulum,that made Ca2+ in endochylema outflow and enter calcium library. Avoided the abnomal higher of Ca2+-ATPase in mitochondria ,lead to Ca2+ overload, protect the mitochondria of muscle cells, also promote the express of the anti-apoptosis genes and reduce the express of the auxo-apoptosis genes in muscle cells, protect the mitochondria in skeletal muscle and improve the sports ability of the exhausting exercising rats on treadmill.