Study Of Preventive Effects Of Chitin Deriviatives On Postmenopausal Osteoporosis

Osteoporosis is a condition characterized by low bone mass;decreasing of the bone mineral content; microarchitectural deterioration of bone tissue, leading to bone fragility; and a consequent susceptibility to fracture.Some symptom such as pain in the back and all the arthrosis will come forth when developed to some extent.Brittle fracture is the ultimate result of osteoporosis, also the severest clinical symptom. So,the osteoporotic fracture and syndrome is the severest influence to the human and the society.Chitin, the second most abundant biopolymer on earth after cellulose, is recognized as a natural, biocompatible, biodegradable, non-toxic, adsorbable and multifunctional resource. Chitin and its derivatives have already been widely applied in many fields such as agriculture, light industry, medicine, biomedicial materials, environmental protection. Recently, much attention has been paid to chitin derivatives with low molecular weight because of their more soluble and special bioactive properties.In the present paper, the low molecular weight deriviatives of chitin such as the glucosamine,chitooligosaccharide,CM-chitooligosaccharide,N-acetyl-D- glucosamine were prepared. According to the regulation of the cell culture, all the samples were purified and their physical properties were tested.Fist, in cell level the effects of the four samples on the proliferation of MC3T3-E1 in vitro. Four samples was dissolved in DMEM with 10% FBS and then diluted with medium in the end the ultimate constration was 10mg/L,100mg/L,500mg/L,1000mg/L,2000mg/L respectively.And then the studies of their effects on osteoblast were researched using MTT assay.The results showed that the four samples can promoted the proliferation of osteoblast, while various concentration has different effects: the proliferation was remarkable when the concentration of GLC, NAG, COS, CM-COS was 100μg/ml, 100μg/ml, 500μg/ml, 500μg/ml respectively. In conclusion, GLC, NAG, COS, CM-COS all have remarkable effect on osteoblast proliferation in vitro, but the effect of GLC and COS are the most among these samples.Three-months-old female Sprague-Dawley rats with the body weight 230±5g (obtained from Qingdao Medical Institute) housed in cages in a temperature and humidity-controlled room (22±2℃and 60±5% relative humidity) with a 12h light-dark cycle and fed a commercial diet containing low calcium. All the animals were randomly divided into 5 different groups: sham group, negative control group, experimental group (high,middle,low does of COS). Each group has eight rats. Negative control group and experimental groups underwent a ovariectomized operation and sham group received a sham operation. After operation, 20000u/time penicilline was injected subcutaneously in every group for three days. After ovariectomy, all rats were fed with the low calcium diets. At the same time rats in negative control groups were fed with 0.9﹪NaCl solution ,the other were fed with different concentration COS solution for 90 days. Body weight was recorded once a week, and the amount of each animal's intake was adjusted every week. The high,middle and low concentration of COS was 0.75g/kg,0.25g/kg and 0.125g/kg respectively. At the end of 8th and 13th week, blood was samplinged to observe the change of indexes. After executing, femur, tibaiae, liver spleen and kidney were carefully removed, and then the study of the index of viscera, the bone mineral density, the bone mineral content, biomechanics and histomorphometry were observed. The results demonstrated that the middle does of GLC and COS can inhibit the increase of body weight resulted from the loss of estrogen after the operation of ovariectomy contrasted to the negative groups. GLCand the middle does of COS can significantly decrease the ALP, TRAP, TG, CHO, LDL, Cr in the serum. The middle does of GLC,the middle and low does of COS can significantly increase the content of Ca,Mg in femur and tibiae. Furthermore, the middle and low does of COS can also increase the content of Fe in tibiae. The bone strength and the biomechanics of ovariectomized rats were increased when fed with the middle does of GLC and the middle,low does of COS. In the study of histomorphometry, the middle and low does of COS can improve Tb.Ar, Tb.Wi, Tb.N of tibiae, at the same time, decrease Tb.Sp. Results: The deriviatives of chitin- GLC, NAG, CM-COS, COS can effectively improve the proliferation of MC3T3-E1 in vitro. After feeding with GLC and COS, the biochemistry indexes were changed, and the biomechanics of bone tissue were also improved. In the micro-architecture, the GLC and COS can better changed it. So GLC and COS can change the high rate of turnover of bone which was the main symptom of postmenopausal osteoporosis. The results of this present paper can hold new proves for the research of new,safe and effective drugs to treat postmenopausal osteoporosis.