The influences of casein phosphopeptides on metabolism of ectopic bone induced by decalcified bone matrix implantation in rats.

The effect of casein phosphopeptides (CPP) on bone metabolism 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 subcutaneously implanted with 30 mg 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 cap phosphatase activity (an index of bone resorption) 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.(ABSTRACT TRUNCATED AT 250 WORDS)