Antiosteoporotic effects of L-Arginine in ovariectomied rats

Objective

To investigate the antiosteoporotic effects of L-Arginine on ovariectomied rats.

Methods

Forty twelve-week-old female Sprague-Dawley rats were randomly divided into four groups of bilaterally ovariectomy and one group of Sham animals, with 8 animals in each group. Twelve additional weeks elapsed before initiation of the treatment with L-Arginine in order to induce significant bone loss in the ovariectomied animals. A 4-week daily treatment (5 days a week, Monday–Friday) at doses of 5 mg/kg/d, 10 mg/kg/d, 20 mg/kg/d of L-Arginine or vehicle only was administered by s.c. injection to the ovariectomied groups respectively. At the end of the treatment period, blood samples from all animals were collected for biochemical analysis. Micro-computerized tomography analysis, histopathological study and biomechanical test were performed on the femur of each animal.

Results

Serum alkaline phosphatase and osteocalcin were reduced in ovariectomied rats after the administration of different dosage of L-Arginine. L-Arginine of 10 mg/kg showed the most significant effect. Micro-computerized tomography 3-D images revealed that the increase of bone mass in 5 mg/kg and 10 mg/kg groups were significant greater than that in Sham group. The biomechanical parameters of femur were improved significantly in L-Arginine 10 mg/kg group when compared to untreated ovariectomied rats.

Conclusions

L-Arginine (10 mg/kg) contributes significantly to the treatment of the bone loss induced by ovariectomy on rats, demonstrated by increased bone mass, improved bone structure and recovery of bone biomechanical activity.