Effects of Zinc Deficiency on Diaphyseal Cortex of the Tibia in the Growing Rat : Combined with Activated Vitamin D_3

Forty 5-week-old Wistar strain male rats, corresponding to childhood in humans, were used to examine the effects of zinc and activated vitamin D_3 on bone formation by intramembranous ossification. 1. Body weight During the whole study the value in the control group was significantly different to that in the low-Zn and VD_3 group, and from the 1st week to the 3rd week the latter showed low (p<0.05) while at the 4th week the latter showed much lower (p<0.01). 2. X-ray findings Compared with the control group, the VD_3 group showed an increase in thickness of the tibial diaphyseal cortex. The low-Zn and VD_3 group showed no change in thickness of the tibial diaphyseal cortex. The high-Zn and VD_3 group showed an increase in width of diaphyseal cortex. 3. Bone mineral content 1) Interosseous marginal cortex There was a significant difference between the high-Zn and VD_3 group and the control group or the low-Zn and VD_3 group, and the former showed the high value (p<0.05). 2) Medial marginal cortex There was a significant difference between the VD_3 group and the control group or the low-Zn and the VD_3 group, and the former showed the high value (p<0.05). There was also a significant difference between the low-Zn and VD_3 group and the high-Zn and VD_3 group, and the latter showed the high value (p<0.01). 4. Hematological test There was no significant difference in electrolytic test, biochemical test or endocrine function test respectively between the control group and the VD_3 group. The value of Ca or P in the control group was significantly different to that in the high-Zn and VD_3 group, and the latter was low (p<0.05) while it was not significantly different to that in the low-Zn and VD_3 group. The value of C-PTH in the control group was significantly different to that in the high-Zn and VD_3 group, and the latter was high (p<0.05). The value of CT in the low-Zn and VD_3 group was significantly different to that in the high-Zn and VD_3 group, and the latter was low (p<0.05). The value of 1, 25(OH)_2D_3 in the control group was significantly different to that in the high-Zn and VD_3 group, and the latter was low (p<0.05). 5. Histopathological findings The VD_3 group, compared with the control group, showed an increase in the bone lacunae between the lateral and the medial basic lamellae, in the Haversian canals and bone lacunae present in Haversian lamellae, and in bone remodeling layer. The low-Zn and VD_3 group, compared with the control group, showed that the density and thickness of bone tissue were decreased, and small bone medullary cavities were obviously seen. The high-Zn and VD_3 group showed that bone tissue was dense and thick. In the interosseous marginal cortical bone, the newly formed trabeculae were obviously seen. The present study suggested that zinc supplementation combined with activated vitamin D_3 could enhance bone formation of the tibial diaphysis in the growing rats and in the conditions of zinc deficiency bone formation could be inhibited in spite of administration of activated vitamin D_3.