The radio-protective effects of n-acetylcysteine(nac)on the radiation-damaged bones

In this study, the radio-protective effects of N-Acetylcysteine (NAC) on the radiation-damaged bones were investigated comparatively with the amifostin. For this purpose some biomechanical parameters of bones such as the ultimate displacement, ultimate force, stiffness, work to failure, young?s modulus, toughness, ultimate stress, ultimate strain and some geometric parameters such as bone mineral density, bone mineral content and cortical area of bone were investigated.For this purpose, 32 rats were divided into Control (C, n=8), Radiation (R, n=8), Radiation+ NAC (R+NAC, 100 mg/kg, i.p, n=8), Radiation + Amifostine (R+WR, 200 mg/kg, i.p, n=8) groups and used. R, R+NAC and R+WR groups were exposed to a single dose of 50 Gy of left femur radiation by using a Cobalt-60 apparatus. At the end of a four-week of experiment, measurements were done on the left femur of each rat using biomechanical and densitometric methods. Bone mineral density was calculated by dual energy X-ray absorptiometry, while the cortical area of bone was measured by computed tomography. Bone Mineral Density (BMD, g/cm2) and Bone Mineral Content (BMC, g) was measured with Dual Energy X-Ray Absorpsiometry (DEXA). Ultimate displacement, ultimate force, stiffness, wor to failure in bone, strain, stress, young?s modulus, toughness were determined the biomechanical parameters with 3- point bending tests. The results were assessed with only side of variation analyze (ANOVA) and Kruskal-Wallis tests.In the measurements, BMD and BMC value of group R stowed adecrease accerding to C group. No any differences obtained between R+NAC and R+WR groups with C groups for these parameters. As a result of biomechanical analyses, the decreases in in displacement, ultimate force, stiffness, work to failure and strain parameters of the femurs in R group were found significant as compared to C group, while the changes in stress, young?s modulus and toughness values of R group were not statistically significant as compared to C group. A comparison of displacement, work to failure, strain and toughness values of R+NAC group with those of C group yielded no statistically different results. Breaking force and stress parameters of R+NAC group were statistically different from those of C group. The increases in stiffness and toughness values of R+NAC group were statistically different from those of R group. The difference resulting from a comparison of stiffness and stress parameters of R+WR group with those of C group was significant.When these results are considered, it might be stated that the protective effect of a low dose of NAC application on radiation-induced bone deterioration is similar to that of Amifostine.