The Influences of Casein Phosphopeptides on Metabolism of Ectopic Bone Induced by Decalcified Bone Matrix Implantation in Rats
1994 Volume 40 Issue 2 Pages 137-145
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1994 Volume 40 Issue 2 Pages 137-145
The effect of casein phosphopeptides (CPP) on bone me-tabolism was studied in the ectopic bone induced by the implantation of decalcified bone matrix in rats. Forty-two Wistar male rats of 7 weeks old were fed low calcium diets (0.39% of calcium) with or without supplying 0.50% of CPP, or a control diet (0.91% of calcium) without CPP supplementation. After a 1-week preliminary period, each rat was sub-cutaneously implanted with 30mg of demineralized bone matrix powder. Fourteen and 21 days after the implantation, the implants were harvested from 7 rats of each group. Calcium content in the graft was not significantly different among all groups on day 14. Subsequently, the content of calcium rapidly increased in the grafts irrespective of diets given. However, the graft of the CPP- group contained less calcium than the other groups and the calcium content was more in the control rats compared to the CPP+ animals on day 21. Alkaline phosphatase activity (an index of bone and cartilage calcification) was lower in the control group than in the CPP+ group on day 14. The enzyme activity subsequently decreased in the control group but the activity was not changed in the other groups. As a result, the activity of alkaline phosphatase was lower in the control animals than in the other rats on day 21. Tartrate-resistant acid phosphatase activity (an index of bone resorp-tion) was higher in the CPP- group compared to the control on day 14. On day 21, the activity was higher in the CPP- group compared to the others. Histological study indicated that the number of osteoclastic cells was larger in the CPP- rats than in the other animals on day 21. These results suggest that CPP supplementation mitigates the reduction of calcium content in bone of rats fed a low calcium diet and that this action of CPP is due to the suppression of bone resorption, which is involved in the reduction of osteoclast differentiation.
