Possible role of low level laser therapy on bone turnover in ovariectomized rats

The aim of this study was to assess the effect of low level laser therapy (LLLT) on bone turnover markers in ovariectomized rats.

Thirty adult female albino rats were divided into three groups; Group 1: 10 sham- operated control rats; Group 2: 10 bilaterally ovariectomized rats (OVX); Group 3: 10 OVX rats exposed to LLLT. LLLT was applied on the neck and shaft of femur, five times per week for 8 weeks. The dose applied on each point was 1000 Hertz, 5 Watts for 30 seconds with a total dose of 15 mJoule/cm². At the end of experiment, blood samples were collected and sera were separated for determination of serum calcium (Ca), inorganic phosphorus (Pi), osteocalcin and alkaline phosphatase (ALP). In addition, a 24 hour urine sample was also collected from each rat for the determination of urinary calcium, phosphorous and deoxypyridinoline (U-DPD)/creatinine.

Significant increase in serum Ca, Pi , ALP, osteocalcin and significant decrease in U-DPD/creatinine in LLLT exposed group was found as compared to the other two groups. Bone morphological findings revealed the increase in calcium deposition and alkaline phosphatase of femoral bones in LLLT exposed group as compared to sham-operated and OVX rats. The software image analysis showed increased osteoblast numbers, decreased osteoclast numbers and increased compact bone thickness in LLLT exposed group. Significant positive correlations was obtained between osteoblast numbers and serum Ca , Pi, ALP and osteocalcin in LLLT exposed group ,while a significant negative correlation was noticed with U-DPD.

The use of LLLT was found effective in enhancing bone formation and decreasing bone resorption in the osteoporotic OVX rats. Further studies are necessary to investigate the effect of different parameters of LLLT as wave length, duration and also numbers of sessions. The potential use of LLLT in postmenopausal women with osteoporosis is needed to be verified.