The effect of L-carnitine in the prevention of ionizing radiation-induced cataracts: a rat model.

Background: The objective was to determine the antioxidant role of L-carnitine (LC) against ionizing radiation-induced cataracts in lens after total cranium irradiation of rats with a single dose of 5 Gy.

Methods: Sprague-Dawley rats were used in this experiment and were divided into three groups. Group 1 did not receive LC or irradiation (control group). Group 2 received a 5 Gy gamma irradiation as a single dose to the total cranium (RT group). Group 3 received total cranium irradiation plus 100 mg/kg body weight/day LC (RT+LC group). The rats were irradiated using a cobalt-60 teletherapy unit. At the end of the 10th day, the rats were sacrificed and their eyes were enucleated. The lenticular activity of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were measured. Furthermore, the lenticular content of an indicator of lipid peroxidation, malondialdehyde (MDA), was measured.

Results: Irradiation significantly increased the MDA level as an end product of lipid peroxidation. Irradiation also significantly decreased SOD activity and increased GSH-Px activity, indicating the generation of oxidative stress and an early protective response to oxidative damage. Irradiation with 5 Gy to the total cranium as a single fraction formed cataracts in the rat lenses. Cataract development was detectable in 9 rats in the RT group, and in only 4 rats in the RT+LC group 10 days after irradiation. LC administration plus irradiation significantly decreased the MDA level and increased the activity of SOD and GSH-Px enzymes, which might indicate the protection of the lenses from gamma radiation-induced cataracts.

Conclusions: L-carnitine may protect against the damage produced by gamma radiation by increasing the activity of the SOD enzyme and by scavenging free radicals generated by ionizing radiation. As a result of this process, MDA as an indicator of lipid peroxidation may decrease.