The Comparative Research On The Effects Of Disuse On The Muscle Protein Metabolism In Hibernating And Non-hibernating Animal

Objective:1. To study the effects of hindlimb unloading on proteolytic rate and collagen protein content of the soleus muscle(SOL) and the extensor digitorum longus muscle(EDL) in rat.2. To study the effects of Ligustrazine on proteolytic rate and collagen protein content of the soleus muscle and the extensor digitorum longus muscle in hind limb unloaded rat.3. To study the effects of hibernation and hindlimb unloading on proteolytic rate and collagen protein content of the soleus muscle and the extensor digitorum longus muscle in ground squirrel(Spermophilus dauricus).Methods:1. Estabish the disuse model of skeletal muscle was achieved by tail-suspension.2. In vitro muscle incubation system with sufficient oxygen supply as well as high performance liquid chromatography were used for detecting proteolytic rate.3. The spectrophotometer was used for detecting collagen protein content of skeletal muscle.Results:1. After 14-day-hindlimb unloading, the proteolytic rate and the collagen protein content of SOL in rat increased 33.6% and 85.5%(P<0.001); no changes was found about the proteolytic rate and the collagen protein content of EDL. Compared with hind limb unloaded rat, the proteolytic rate and the collagen protein content of SOL in hindlimb-unloading plus intragastric Ligustrazine instillation group decreased 15.5%(/P<0.05) and 9.4%(P>0.05).2. After 14-day-hindlimb unloading, the proteolytic rate and the collagen protein content of SOL in ground squirrel increased 21.5(P<0.01) and 32.8%(P<0.05); no changes was found about the proteolytic rate and the collagen protein content of EDL.3. Compared with pre-hibernation group, the proteolytic rate of SOL and EDL in hibernation group decreased 73.3% and 71.3%(P<0.001); the proteolytic rate of SOL and EDL in post-hibernation group decreased 19.9%(P<0.01) and 12.5%(P>0.05).4. Compared with pre-hibernation group, the collagen protein content of SOL and EDL in hibernation group increased 22.4% (P>0.05) and 56.0%(P<0.01); the collagen protein content of SOL and EDL in post-hibernation group increased 40.7%(P<0.05) and 94.6%(P<0.01).Conclusion:1. The increase of proteolytic rate of SOL in hind limb unloaded rat or ground squirrel directly leads to the disuse atrophy of skeletal muscle.2. The increase of collagen protein content of SOL in hind limb unloaded rat or ground squirrel has significant relationship with the progression and development of disuse atrophy of skeletal muscle.3. The proteolytic rate of skeletal muscle can be decreased by Ligustrazine, this may be the major reason that Ligustrazine can prevent muscle atrophy.4. The effects of hindlimb unloading on proteolytic rate and collagen protein content of SOL and EDL in rat showed more significant than ground squirrel, this express that ground squirrel possiblely have the ability of anti-disuse atrophy during non-hibernation.5. The sharp decrease of proteolytic rate of SOL and EDL in ground squirrel during hibernation may be one of the ground squirrel's mechanisms of anti-muscle atrophy during hibernation.