| BackgroundTo experiment on astronauts as the experimental subjects is spatial human experiment. This human experiment is not only expensive but also strictly limited by experimental conditions. Firstly, there are few subjects and limited measurement methods. Secondly, the experimental conditions are not easy to control. As the results it'll inevitably decrease the other space experiment projects. Subject to the limitations of spatial human experiment, most basic researches of space medicine have to process in laboratory. Then the research subjects are usually animals. This time osteoporosis animal models are introduced in this research. The animal model means nosogenesis caused by physics, chemistry and biology acts on the animals. That'll result a certain extent injury in animal tissues, organs or the whole body. Namely, some similar functions, metabolic disorder or conformation pathological changes of human disease appear. This method is commonly applied in neoteric biomedical research institute. Especially, the first choice for drug screening studies.There are two main purposes of this research. One is to observe effect of the weightless simulated rat's bone tissue tectology by SR intervention that given to it. The angles of observation may be different. They are bone mineral density or bone ultrastructure or others. The other purpose is to provide experimental basis for future clinical drug trial. Then weightlessness should be presented here. Weightlessness is a kind of special mechanics environment that means the object does not represent manifest weight but mass. The special mechnics enviroment actually is Microgravity. Microgravity is a state in which gravity is reduced to almost negligible levels, such as during space flight. The space flight falls under small non-gravitational forces and results very a small acceleration. Usually, this non-gravitational acceleration is only one ten thousandth of the ground acceleration of gravity or even less. It is commonly defined as the 10-6-10-4g. In order to compare with the normal gravity, the micro-acceleration phenomenon is named microgravity. The less microgravity is, the more complete zero gravity is. In a word, zero gravity is only an ideal state. Just micro-gravity is practical circumstance. It's a very important sign to judge that one object whether is in zero gravity state or not. There is no interaction force between each part and each particle of the internal object. Namely, there is no any stress like pull, press, cutting-forces and so on. However, this is one of important mechanisms that cause osteoporosis under zero gravity state. There is no interaction between animal models or each particle of human. Namely, it'll cause disused osteoporosis by stressless stimulation. Osteoporosis (Osteoporosis, OP) is a kind of reduction in bone mass and damage in bone micro-structural, which will lead to some diseases easily like characteristic bone fragility and fracture diseases.There will be series physiological changes through astronauts'body under weightlessness during space flight's operation time. Bone metabolic disorders harm human's body more serious. And the bone metabolism disorder is mainly manifested disuse osteoporosis during astronauts' flight. The representations of invisible osteoporosis caused by weightlessness mainly show as rare bone loss, bone demineralization, density reduced, decline in mechanical properties of bone, fecal calcium and urine calcium increased, blood calcium increased, showed a negative calcium balance. The general clinical bone osteoporosis disease is caused by endocrine disorders. The distribution bases on time of human life in the colony. But due to weightlessness skeleton structure function changes that is caused by gravity environmental changes. Human space experiments research limits under number of strict conditions. There are few subjects and limited measurement methods. Besides, the experimental conditions are not easy to control. Therefore, the premise of space medicine research is to choose a model animal that is applicability, controllability, feasibility as well as economy. Weightless simulated rat induced disuse osteoporosis that can be replicated as human space disease models and it has good repeatability.This research can confirm the tail suspension method is available. This method can realize the expectant osteoporosis animal models by observing the growth instance of rat osteoporosis animal models, the testing of bone metabolism biochemical index, bone ultrastructure scanning electron microscope. Since the model is available, the osteoporosis group animals are made a drug intervention. When the experiment was finished, detection of biochemical index of group C in rat bone metabolism and scanning electron microscopy of bone ultrastructure should be tested, then it should be compared with non-interference group. The result is that the drug given can improve effectively the bone density, bone mineral content as well as bone ultrastructure of osteoporosis animals.ObjectiveAfter successful modeling, give strontium ranelate(SR) for drug intervention. Then observing the rats blood biochemical parameters, bone mineral density, bone content, bone proportion, and bone ultrastructure changes of comparison group and treatment group. Through the establishment of simulated weightlessness rats osteoporosis model, assessing the effects of SR in preventing and curing simulated weightlessness male rats osteoporosis. It is an experimental basis for SR in clinical future application.MethodPrepare 3-month-old SPF level 27 male SD rats. Stochastic average divided the rats into 3 groups:A group is non-tail-suspended freely comparison group; B group is lost re-simulation of tail-suspended; C group is tail-suspended simulated weightlessness. Strontium ranelate (600mg/kg/d) gavage in C group. A group and B group gavage equal brine. Gavage is one times a day, every 4 days weighting one time, according the body weight to adjust dosage.3 group rats were all feed in single cage and free eating and drinking purified water. Experimental period is 28 days. After the experimental expiration, each group rats intraperitoneal anesthesia by 3% pentobarbital sodium (50mg/kg). Execute via left ventricular bleeding. Take anti-coagulation 3 ml and put at room temperature place for 1 hour. Centrifugation (3000 r/min, 10min) separate serum. Sending the serum to testing in time and test serum calcium (Ca), Phosphorus (P), alkaline phosphatase (ALP). Get the rat's right thighbone, clean the surrounding soft tissue, measuring thighbone mineral density, bone mineral content and bone area. Crossing amputated the thighbone at the femoral neck, Taking the femoral neck segment. After fixation, washing, dehydration, drying then make the vacuum spray gold. Eventually, In the scanning electron microscope to observing the status of femoral neck trabecular bone distribution, quantity, thickness and collagen alignment, fracture and so on.Statistical Methods:All data expressed mean value±standard deviation, using SPSS 13.0 statistical software for statistical analysis, using 2 independent-samples t test and variance analysis (One-way ANOVA) between groups, LSD multiple test, P<0.05 as significant difference test standard.Results(1)The general growth of ratPeriod of the entire experiment, rat activity freely, hair is thick and shiny. Experiments on day 4 B group and C group rats body mass decreased compared with before the experiment (P<0.01). Henceforth, the 3 group rats body weight increased remained stable and no evident difference between the two groups (P> 0.05). After experiment expiration, B and C group rats body mass decreased compared with group A, but no evident difference (P> 0.05).(2) Biochemical index mensuration results of bone metabolismAfter 28 days suspension, The serum alkaline phosphatase (Alkaline phosphatase, ALP)of B group rat was obvious higher than A group (P<0.05); C in serum ALP content of C proup rats were distinct lower than B group (P<0.05); Between each group, the calcium, phosphorus content showed no notable difference (P> 0.05). A group and C group no prominent difference (P> 0.05). (3)Rat right thighbone BMD (Bone Mineral Density),BMC(Bone Mineral Content), and BA (Bone Area), mensuration resultsBMD, BMC of B group rat's thighbone was distinct lower than A group (P= 0.000, P= 0.000); The BMD, BMC of C group was notable higher than B group (P= 0.001, P= 0.011). BMD, BMC of A group and C group was no significant difference (P= 0.249, P= 0.242). BA values among the 3 groups have no difference (P= 0.065, P= 0.229, P= 0.524).(4)Result of scanning electron microscopyObserving compare of 3 group rats under low magnification microscope:A group rats with more number of thighbone neck trabecular bone, trabecular thickness is normal, distributionrelative unification, forming a tridimensional network structure; B group rat bone marrow cavity expansion, bone trabecular number decreased, the distance between trabeculae increased, absorption of hole sizes and shapes is differ, trabecular thinning, uneven thickness, some trabecular bone create dead-end dissociate in marrow cavity, the tridimensional network structure be damaged; The femoral neck trabecular bone number of C group rats compared with group B increased, trabecular thickness increased, As a whole,the distribution is comparative even, and basically formed a tridimensional network structure.Conclusion:1. Through the tail suspension, osteoporosis animal model was established successfully. The induced animal models showed bone loss and bone mass reduction; bone micro-structure was destroyed; Tail-suspension simulated osteoporosis rats model were successfully established.2. Strontium Ranelate can improve the simulated weightlessness osteoporosis rat's bone density and bone mineral content.3. Strontium Ranelate can improve the simulated weightlessness osteoporosis rats femoral ultrastructure, increased femoral neck trabecular bone volume and thickness, improve the alignment of collagen.4. Strontium Ranelate can distinct reduce simulated weightlessness rats femoral neck bone loss, increase bone formation, prevention and cure osteoporosis. |
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