Nitric oxide plays an important role in bone metabolism. However, the effects of different doses of L-arginine, nitric oxide substrate, on the healing of osteoporotic fractures remain unclear.OBJECTIVE:
To investigate the influence of different doses of L-arginine on the healing of osteoporotic fractures and blood biochemistry in rats.METHODS:
A total of 50 female Wistar rats, aged 6-month-old, were randomly divided into sham-surgery (n=10) and osteoporosis (bilateral ovariectomy, n=40). After osteoporosis model was established, left middle femoral fractures were made in all 50 rats, and the osteoporosis group was further divided into four groups, low, middle and high dose of L-arginine, and control groups. The L-arginine groups were intraperitoneally injected with 1, 3, and 5 mg/kg L-arginine at the second day following surgery, while the control and sham-surgery groups were injected with the same volume of normal saline. At 8 weeks, the lumbar and callus bone mineral density, serum nitric oxide, and nitric oxide synthase were detected. Meanwhile, the bone callus histological examination was conducted.RESULTS AND CONCLUSION:
During fracture healing, osteoporosis rats showed a low level of serum nitric oxide and nitric oxide synthase compared with normal fractured rats (P < 0.05). L-arginine can improve the concentration of serum nitric oxide and nitric oxide synthase in osteoporosis rats. Moreover, middle dose of L-arginine can increase the callus and lumbar spine bone mineral density of osteoporosis rats, so the number and continuity of bone trabecula were enhanced. These findings suggest that middle dose of L-arginine (3 mg/kg) can promote healing process of osteoporotic fractures and improve osteoporosis.