Caffeic acid phenethyl ester (CAPE) is one of the major components of honeybee propolis. It has been used in folk medicine for many years in Middle East countries. Melatonin and CAPE were found to be potent free radical scavengers and antioxidants.
Melatonin (100 µg/kg) or CAPE (10 µM/ml per kg per day) were administered daily for 60 days to the animals prior to their electromagnetic field exposure.
|Repetition frequency||217 Hz|
|Setup||A special exposure device with six-exposure antennas for insulated exposure was used. The exposure system for an animal consisted of a plastic tube cage (length 12 cm, diameter 5 cm) and a half wave dipole antenna. The head of the rat was positioned in close contact above the dipole antenna. The tube was ventilated from head to tail.|
Retinal levels of nitric oxide and malondialdehyde increased in the electromagnetic field exposed rats while both melatonin and CAPE caused a significant reduction in the levels of nitric oxide and malondialdehyde.
Likewise, retinal superoxide dismutase, glutathione peroxidase and catalase activities decreased in electromagnetic field exposed animals while melatonin and CAPE caused a significant increase in the activities of these antioxidant enzymes in the exposed animals to higher levels than those of control rats.
In conclusion, melatonin and CAPE reduce retinal oxidative stress after long-term exposure to 900 MHz emitting mobile phone. Nevertheless, there was no statistically significant difference between the efficacies of these two antioxidants against to electromagnetic field induced oxidative stress. The difference was in only glutathione peroxidase activity. Melatonin stimulated the retinal glutathione peroxidase activity more efficiently than CAPE did.