Correlation between lipid-lowering and bone-protective effects of eicosapentaenoic acid in rats with steroid-induced bone loss

This study was conducted to investigate the correlation between lipid-lowering and bone-protective effects of eicosapentaenoic acid on steroid-induced bonechanges in rats. Twenty-one male 10-week-old Wistar rats were divided into 3 groups (n = 7 each) and treated with 0.9% NaCl SC (group 1) or methylprednisolone 7 mg/kg SC once a week (group 2) or methylprednisolone 7 mg/kg SC once a week + eicosapentaenoic acid 160 mg/kg, PO daily (group 3), for 6 weeks. At the end of the experiment, serum total cholesterol and triglycerides concentrations were determined using enzymatic colorimetric assays and bone histomorphometric analyses were performed on cancellousbone of femoral epiphysis and metaphysis using a photomicroscope and a digital camera. Histomorphometric parameters demonstrated a significant bone loss due to methylprednisolone administration, which was partly restored by eicosapentaenoic acid. A strong inverse correlation was observed between the serum total cholesterol concentration and epiphyseal trabecular width and metaphyseal trabecular osteoid width (R = -0.82, P = 0.04 and R = -0.86, P = 0.01, respectively). Serum triglycerides concentration was also strongly and inversely correlated with the above mentioned parameters (R = -0.88, P = 0.02 for epiphyseal trabecular width and R = -0.81, P = 0.02 for metaphyseal trabecular osteoid width). The correlation between the lipid-lowering and bone-protective effects of eicosapentaenoic acid may be helpful in the clarification of its effects on bone and lipid metabolism.