成長発育期ラットの運動負荷による骨組織への影響 : 脛骨骨幹皮質骨について

Abstract

For this study, male Wistar rats at the growth stage were given physical exercise and food of different calcium contents and intramembranous ossification of the cortex of diaphysis tibia was investigated. The results were as follows : I. Findings on bone density Standard diet with exercise group showed higher values (p<0.01) for intraosseous cortex and medial cortex than standard diet with no exercise groups. No significant differences were found among calcium-deficient groups. Comparison between any pair of standard diet with no exercise group and calcium-deficient group showed significant differences and standard diet with no exercise groups showed higher values (p<0.01). Significant differences were shown between intraosseous cortex and medial cortex intraosseous cortex showed higher values in all of the following groups : standard diet with no exercise group (p<0.01), calcium deficient diet with no exercise group (p<0.01), calcium deficient diet with one-exercise group (p<0.01), and calcium deficient diet with two-exercise group (p<0.05). II. Histopathologic findings As compared with standard diet with no exercise group, standard diet with 2-exercise group especially showed significantly bone remodeling layers, increase in bone quantity, cement lines, degree and thickness of calcification of inner and outer circumferential lamellae, and findings of displacement of bone lacuna with bone, and these expedited formation of bone matrix. Calcium deficient diet groups showed enlargment of marrow, bone resorption, decrease in Haversian system, undermineralized layers, decrease in Haversian lamellae, decrease in inner and outer circumferential lamellae, decrease in bone lacunae, and showed about the same findings as the exercise groups. III. Compression strength of bone Among the standard diet groups, the group with 2-exercise showed the highest compression strength (p<0.01). Among the calcium deficient diet groups, no differences were shown between any two groups. Between the standard diet group and calcium deficient group, significant differences were found in all and the standard diet group showed greater strength (p<0.01). On the basis of the foregoing findings, physical exercise given to rats at the growing stage expedites increase in bone quantity although it differes with the degress of mechanical load placed on the cortex of diaphysis of tibia, and has an effect of promoting formation of bone matrix. Importance of the correlation with calcium deficiency was suggested.