| Osteoporosis is a systemic metabolic skeletal disease, characterized by low bone mass and microarchitectural deterioration of bone tissue with a consequent increasing in bone foragility and susceptibility to fracture. Osteoporotic fracture (commonly to vertebra, hip and wrist), causing severe chronic disease, makes us particularly concern. Now in the USA, around 30% of menopause white women suffer from osteoporosis and there are about 54% white women with low bone mass in their hip, spine and carpal bones. Within one year after fracture, 28% patients with hip fracture are pushed into the sanatorium; 5% to 20% of patients die of a variety of complications. It is a big challenge and pressing mission confronted with us to research and treat osteoporosis.Estrogen replacement therapy (ERT) has become the first optional drug since it was used in treating osteoporosis in the 1960's. However, it can cause such troubles as: vaginal bleeding, gaining weight, the possibility of endometrial carcinoma and breast cancer, which are reported in recent foreign materials. There is always controversy in calcium preventing and treating osteoporosis. Some writers believe that calcium can increase bonemass in puberty, however, it is invalid to adults who intake normal amount of calcim. Because of the extent to absorb ,a number of specialists suggest that it is good to supply by means of food. Calcitionin is chiefly used by patients who are invalid to estrogenic hormone, but it can not increase BMD but improve bone tissue. Now, calcitionin is dependent on import and expensive. Its application and spread are limited to some extent, Fluorol can accelerate osteocytes to reproduce and prolong cycle, result in raising BMD. At the same time fluorol increase the possibility of fracture.Nitric Oxide (NO) is a free radical involved in the regulation of many physiological processes, such as vascular relaxation, neuvotransmission, platelet agrregation and in immune regulation. Over recent years it has become apparent that NO has important effect on bone cell function. NO plays a key role in the bone resorption mechanism by inhibiting the activity of osteoclasts. However its function is associated with its density. It has been shown that low level of NO in bone cause bone resorption and increase bone mass loss. While bone formation increased with higher level of NO. All these became the foundation for nitric oxide donor to treating osteoporosis. Objective:To investigate the rule of bone mass changes in ovariectomized rats, to study the effect of different dosage nitric oxide donor (nitroglycerin) to rats after ovariectomy and to study the mechanism of nitroglycerin to treat osteoporosis, it will provide theoretic and experimental data for nitric oxide donor (nitroglycerin) in clinically treating osteoporosis.Methods:In this study 60 female SD rats of three or four months old, were offered by the animal center of Henan Medical university. Fifty rats were selected at random and ovariectomized. After testing, they were divided at random into five groups: ovariectomied group (OVX group), OVX plus low dosage nitroglycerin group(OVX+LNG group), OVX plus middle dosage nitroglycerin group (OVX+HMG group) and estrogen replacement therapy group (ERT group); ten rats in each group. The rest 10 rats without ovariectomizing became sham operated group (SO group). A week later, all groups began to treating by oral gavages. Nine weeks later some measures were taken as follows: 1) Bone mineral density (BMD) ; 2) their serum is taken to detect the level of E2. Ca. P. ALP; 3) the level of NO in serum; 4) the weights of dried right femur bone, its ash and the content of calcium in the ash; 5) the histomorphometry of bone tissue. Statistical data were described as mean + SEM. According to the statistical principles, data were compared with analysis of variance.Results:1) BMD:OVX group was significantly lower than SO group (P<0. 05) ; OVX+LNG group and OVX+MNG group were significantly higher than OVX group (P<0.05, P<0.01); no statistical...
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