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Experimental Study On The Effects Of Combination Of Different Intensity Exercise And Estrogen On Bone In Ovariectomized Rats

Posted on:2005-01-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:X S ZhangFull Text:PDF
GTID:1117360122493637Subject:Human Movement Science
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Experimental study on the effects of combination of different intensity exercise and estrogen on bone in ovariectomized ratsSpeciality: Sports Kinetics Tutor: Pro. Xu Haowen Postgraduate: Zhang XiaoshuangOsteoporosis is characterized by abnormally low bone mass and micro-architectural deterioration of bone tissue, leading to an increase in bone fragility and a consequent increase in fracture risk. The mechanism of the effect of exercise on bone is unclear. To evaluate the effect and mechanism of individual or combined different intensity treadmill exercise and estrogen on bone in ovareictomized rats, 80 female Sprague Dawly rats,3months of age, were either sham-operated (SHAM) or ovariectomized(OVX) and assigned as following ten groups. 4 groups of control: BASAL (baseline group), SHAM, OVX and OVX+ES (ovariectomy with estrogen administration), 3 groups of individual exercise of different intensity : 0VX+EX1, 0VX+EX2 and 0VX+EX3, 3 combined groups of estrogen and exercise:OVX+EXl+ES, OVX+EX2+ES, and OVX+EX3+ES. Exercise consisted of treadmill running for lh/day,5days/week,at the 5 degree elevation and the speed of 8m/min(low intensity exercise,EXl), 18m/min (moderate intensity exercise,EX2) and 28m/min (high intensity exercise, EX3) with the duratin of 8 weeks. Histomorphometric measurement on the concellous bone in proximal tibia metaphysis (PTM) and the 4th lumbar vetebral body(L4), bone mechanical properties in femoral neck (FN) and 2nd and 3rd lumbar vetebral body (L2,L3) and the serum levels of estradiol (E2) and calcium (Ca) and phosphate (P) were investigated.1. Effects of combination of different intensity exercise and estrogen on bone mass in ovariectomized rats.In this part, histomorphometric measurements were performed on the cancellous bone in proximal tibia metaphysis and 4th lumbar body (L4), while the body weight, food intake, femur length and the weight and volume of triceps surae were mesured. The results indicated as follows: (1) The body weight increased significantly (p<0.05) in ovariectomized rats because of increasing in food intake and this can be prevented (p<0.05) by estrogen administration but not the exercise (p>.05). (2)Ovariectomy led to cancellous bone loss significantly (p<0.05) in PTM and L4 by increasing bone formation and resorption due to estrogen-depleting, whereas it can be diminished by estrogen administration. (3)The effect of individual exercise on bone mass. Therewere site-specific differences on skeletal response to individual exercises. In PTM, which is the site imposed directly by mechanical load, the response of skeleton to exercise was related to exercises intensity and the action of EX1 and EX2 on bone mass was liner positive (p<0.01) (EX2 better than EX1) by decreasing bone resorption and increasing bone formation, but that of EX3 was not. In L4, the site imposed indirectly by mechanical load, the response of skeleton to exercises was the global increase in bone mass in all of the three individual exercise groups and a liner positive correlation(p<0.01) between exercise intensity and bone mass, suggesting that the higher the exercise intensity is, the more the bone mass is . (4) The effects of combination of exercise and estrogen on bone mass. In PTM, there was a much better collaborate reaction of skeleton on exercises in three combined groups than that in the groups of estrogen administration alone and exercise alone, and a positive liner correlation (p<0.01) between the exercise intensity and bone mass was obtained also. The level of bone mass in the combined groups is the same with the group of BASAL by inhibiting bone formation and bone resorption. In L4, there was no collaborate effect in combination groups even though it also has the better effect than OVX group. It was conclusion that the responses of skeleton to exercise depended on whether or not the bone was the site loaded directly and whether or not estrogen administration of ovariectomized rats were performed.2. Effects of combination of different intensity exercise and estrogen on the serum...
Keywords/Search Tags:Osteoporosis, Different intensity, Treadmill exercise, Bone, Bone histomorphometry, Bone mass, Bone biomechanical property, Estrogen, Calcium, Phosphate Tibia, Lumbar, Femur, Femoral neck
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