A balanced diet is crucial for healthy development and prevention of musculoskeletal related diseases. Diets high in fat content are known to cause
obesity, diabetes and a number of other disease states. Our group and others have previously reported that activity of the
urea cycle
enzyme arginase is involved in diabetes-induced dysregulation of vascular function due to decreases in
nitric oxide formation. We hypothesized that diabetes may also elevate
arginase activity in bone and bone marrow, which could lead to bone-related complications. To test this we determined the effects of diabetes on expression and activity of
arginase, in bone and bone marrow stromal cells (BMSCs). We demonstrated that
arginase 1 is abundantly present in the bone and BMSCs. We also demonstrated that
arginase activity and expression in bone and bone marrow is up-regulated in models of diabetes induced by HFHS diet and
streptozotocin (STZ). HFHS diet down-regulated expression of healthy bone metabolism markers (BMP2, COL-1, ALP, and RUNX2) and reduced bone mineral density, bone volume and trabecular thickness. However, treatment with an
arginase inhibitor (ABH) prevented these bone-related complications of diabetes. In-vitro study of BMSCs showed that high
glucose treatment increased
arginase activity and decreased
nitric oxide production. These effects were reversed by treatment with an
arginase inhibitor (ABH). Our study provides evidence that deregulation of
l-arginine metabolism plays a vital role in HFHS diet-induced
diabetic complications and that these complications can be prevented by treatment with
arginase inhibitors. The modulation of
l-arginine metabolism in disease could offer a novel therapeutic approach for
osteoporosis and other musculoskeletal related diseases.