Comparison of protective effects of L-carnitine and amifostine 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) in growing bones in comparison to amifostine.

Materials And Methods: Sixty two-week-old Wistar albino rats were randomly 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, amifostine alone (AMI); Group 6, L-carnitine alone (LC). The rats in the AMI+ RT, LC+ RT and RT groups were irradiated individually with a single dose of 20 Gy to the left femur. LC (300 mg/kg) and amifostine (200 mg/kg) were applied 30 min before irradiation. The animals were scanned for bone area, mineral content and bone mineral density (BMD) by DEXA and the 99mTc methylene diphosphonate uptake ratio (MUR) was calculated by bone scintigraphy. 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= 0.04 respectively) and in the epiphysial cartilage (p= 0.002 and p= 0.015 respectively). The protective effect of LC was similar to that of amifostine on both growing bone and on the epiphysial cartilage. The mean left-femur BMD values were significantly higher in the LC+RT (p= 0.02) and AMI+RT (p= 0.01) groups than in the RT group. but did not differ with the two protective agents. Pretreatment with AMI (p= 0.002) and LC (p= 0.01) improved the MUR.

Conclusions: L-carnitine is equally as effective as amifostine at protecting growing bone against single dose irradiation damage.