Effects Of Different Exercises On BMD And Biochemical Indexes Of Bone Metabolism And Osterix In The Growing Rat After Simulated Weightlessness

This study was designed to explore the mechanism of vertical jump and swimming for the prevention of simulated weightlessness on bone in rats, and compared these two sports models to analyze their different impacts on bone metabolism. By simulating the preventive training before astronauts landing the space, I conducted quantitative research on rats'bone density, bone mechanism and the osteoblast-specific transcription factor Osterix(Osx), so as to explore the causes, and indirectly provide the necessary theoretical basis for the environmental impact on developing bone mass, the use of various interventions in recovery process, and the choices of different movements, as well as offer some references to the pre-training before the astronauts moving into space.[Objective]1. Study the effects of different forms of exercise on BMD in simulated weightlessness rats;2. Study the effects of different forms of exercise on the biochemical indexes of bone metabolism (BGP, StrACP) in simulated weightlessness rats;3. Study the effects of different forms of exercise on the osteoblast-specific transcription factor Osterix(Osx) in simulated weightlessness rats.4. Analysed whether exercise have precautionary effects, and which movement pattern is much better, so as to offer a theoretical basis for the choice of movement and the formulation of exercises prescriptions during bone loss.[Method]Set up the rat vertical jump, swimming exercise model, choose twenty four 4-week-old SD rats as subjects and randomly divide them into 3 groups:Quiet & tail-suspended group, jump & tail-suspended group, and swimming & tail-suspended group. After 8 weeks training, make 2 weeks of tail-suspension according to Chen jie's model of the rat tail-suspension and improved methods. After 2 weeks of tail-suspension, test their body weight, then killing the rats, test their bone mineral density, bone morphology index and bone metabolic markers.1. Observe the rats'diet, activity, coat color, weight and their response during exercise and tail-suspension, and take notes.2. Using HOLOGIC Discover A to detect the rats'femur bone and lumbar bone's BMD.3. Measure the length, mid-width and mid-thickness of femur and tibia by using the vernier callipers.4. Use the microplate reader and the kit which bought from Nanjing Jiancheng Biology Company to detect the tartrate-resistant acid phosphatase levels in rats'blood, and use the kit which bought from Shanghai Ruicong Company to detect the osteocalcin levels in blood.5. Measure the level of Osterix (Osx) in femur cartilage tissue by the technique of real-time fluorescence quantitative PCR, and explore the mechanism of the variations.[Result]1. During experiment the rats moved and ate freely. At the outset of the experiment, there are no differences between the three groups on weight. After 8 weeks'training, the weights of them are all increased. The jump & tail-suspended group and swimming & tail-suspended are obviously different from the quiet & tail-suspended group on weight (P<0.05). After 2 weeks tail-suspending the weights of those rats are all decreased, but the difference is not obvious (p>0.05).2. Compare the morphological indicators of femur and tibia in the rat:statistically there are no significant differences in general (P>0.05), but we can find that the length of femur, the mid-width and mid-thickness of tibia in jump & tail-suspended group have an increasing tendency.3. Compare the BMD of femur in the rat:The jump & tail-suspended group has obvious difference compared with the quiet & tail-suspended group (P<0.01); the swimming group shows the decreased trend on BMD compared with the quiet & tail-suspended group, and the difference is not obvious (P>0.05).4. Compare the BMD of tibia in the rat:The jump & tail-suspended group has obvious difference compared with the quiet & tail-suspended group (P<0.05); the swimming group shows the decreased trend on BMD compared with the quiet & tail-suspended group, and the difference is not obvious (P>0.05).5. Compare the level of OT in the rat:The jump & tail-suspended group has obvious difference on the level of OT compared with the quiet & tail-suspended group (P<0.05); the swimming & tail-suspended group has no obvious difference on the level of OT compared with the quiet & tail-suspended group (P>0.05).6. Compare the level of StrACP in the rat:The jump & tail-suspended group have remarkable difference on the level of StrACP compared with the quiet & tail-suspended group (P<0.01); the swimming & tail-suspended group have obvious difference on the level of StrACP compared with the quiet & tail-suspended group (P<0.05).7. Use the real-time fluorescence quantitative PCR to detect the expression of Osterix imRNA. The jump& tail-suspended group has obvious increase on the level of Osx mRNA, compared with the quiet & tail-suspended group (P<0.05); and the swimming & tail-suspended group has an increasing tendency, but has no statistically significant differences(p>0.05).[Conclusion]1. The study found that tail-suspending can lower the level of bone density, bone forming activities, bone metabolic biochemical indicators, and the morphology index of femur and tibia. The main formation mechanism of tail-suspending is inhibiting the bone absorption, and exercise could curb the occurrence of the process to a great extent.2. Compared the difference between vertical jump and swimming, and found that different kinds of movement patterns have different effects on preventing bone loss in simulated weightlessness rats. After 8 weeks of training, the levels of BMD, bone metabolic biochemical indicators, and the morphology index in femur and tibia have obvious changes. The jump & tail-suspended group is better than swimming & tail-suspended group on most indices, thus show that jump can effectively promote the formation of bone, and can make great effects on bone metabolism with smaller strength.3. The metabolic change caused by exercise is relevant to the effect of local factor made to the bone tissue. Make a preliminary exploration on the relationship between exercise and osteoblast specific transcription factor Osterix(Osx), analyze the exercise effect on Osx, and the Osx effect on bone metabolism. Think that sports might promote the bone formation by promoting the expression of Osx, and the moderate jump exercise is superior than swimming.