Comparison of the protective effects of melatonin and amifostine on radiation-induced epiphyseal injury.
OBJECTIVE
We compared the effects of amifostine and melatonin in preventing radiation-induced epiphyseal growth plate injury in rats.


METHODS
Four-week-old (65-85 g), growing male Sprague-Dawley rats were randomly assigned to receive radiation alone, at 25 Gy in three fractions (group R), or this dose of fractionated radiation proceeded by prophylactic amifostine 200 mg/kg i.p. (group A), melatonin 15 mg/kg i.p. (group M), or amifostine + melatonin (group AM). The right rear extremity of each animal was irradiated while the contralateral leg was shielded from radiation, as a control. Bone growth based on the length of the tibia, femur, and overall limb was calculated 6 weeks after the treatment.


RESULTS
In groups R, A, M, and AM, the mean growth loss (GL) for the overall limb was 56.9 +/- 8.1%, 46.8 +/- 7.7%, 36.6 +/- 4.3%, and 38.5 +/- 5.1%, respectively. The limb length discrepancies (LLD) in groups R, A, M, and AM were 13.8 +/- 1.4%, 10.5 +/- 0.3%, 7.4 +/- 0.7%, and 8.8 +/- 1.1%, respectively. Differences in LLD were significant between each treatment group and group R (range: p = 0.0001-0.001). Differences in either of mean GL and LLD were not significant between groups M and AM; however both of these groups had significantly less GL and LLD than group A.


CONCLUSIONS
We observed a superior radioprotective function of melatonin over amifostine in preventing radiation-induced epiphyseal growth plate injury, without any increase in radioprotective effect by adding amifostine to melatonin.
Topkan
Erkan
E
Baskent University Medical Faculty, Adana Medical and Research Center, Department of Radiation Oncology, Kisla Saglik Yerleskesi, Adana, Turkey. drerkantopkan@yahoo.com
Tufan
Hale
H
Yavuz
Ali Aydin
AA
Bacanli
Didem
D
Onal
Cem
C
Kosdak
Sebnem
S
Yavuz
Melek Nur
MN
D004999:Amifostine / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001846:Bone Development / Q000187:drug effects / Q000528:radiation effects; D019583:Dose Fractionation, Radiation; D005121:Extremities / Q000254:growth & development / Q000503:physiopathology / Q000528:radiation effects; D006132:Growth Plate / Q000187:drug effects* / Q000503:physiopathology / Q000528:radiation effects*; D008297:Male; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D011833:Radiation Injuries, Experimental / Q000188:drug therapy* / Q000517:prevention & control*; D011837:Radiation-Protective Agents / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000072042:Salter-Harris Fractures
D011837:Radiation-Protective Agents; D008550:Melatonin; D004999:Amifostine