Comparison of Protective Effects of L-Carnitine andAmifostine on Radiation-induced Toxicity to Growing Bone:Histopathology and Scintigraphy Findings

Purpose: The aim of the present study was to evaluate the radioprotective efficacy of L-carnitine (LC) ingrowing bones in comparison to amifostine. Materials and
Methods: Sixty two-week-old Wistar albino rats wererandomly assigned to six equal groups: Group 1, control (CONT); Group 2, irradiation alone (RT); Group 3,amifostine plus irradiation (AMI+RT); Group 4, L-carnitine plus irradiation (LC+RT); Group 5, amifostinealone (AMI); Group 6, L-carnitine alone (LC). The rats in the AMI+RT, LC+RT and RT groups were irradiatedindividually with a single dose of 20 Gy to the left femur. LC (300mg/kg) and amifostine (200mg/kg) wereapplied 30 min before irradiation. The animals were scanned for bone area, mineral content and bone mineraldensity (BMD) by DEXA and the 99mTc methylene diphosphonate uptake ratio (MUR) was calculated by bonescintigraphy. Histopathological analysis of bone and cartilage was also carried out after euthanasia.
Results:Pretreatment with LC or amifostine reduced the radiation-induced damage in growing bone (p=0.007 and p=0.04respectively) and in the epiphysial cartilage (p=0.002 and p=0.015 respectively). The protective effect of LC wassimilar to that of amifostine on both growing bone and on the epiphysial cartilage. The mean left-femur BMDvalues were significantly higher in the LC+RT (p=0.02) and AMI+RT (p=0.01) groups than in the RT group. butdid not differ with the two protective agents. Pretreatment with AMI (p=0.002) and LC (p=0.01) improved theMUR.
Conclusions: L-carnitine is equally as effective as amifostine at protecting growing bone against singledose irradiation damage.