Effects of melatonin, vitamin E and octreotide on lipid peroxidation during ischemia-reperfusion in the guinea pig retina.
OBJECTIVE
The purpose of this study is to provide evidence that free radical damage is a component of retinal ischemia-reperfusion (I/R) injury, and to determine whether melatonin, vitamin E and octreotide can protect the retina from this injury.


METHODS
The right eyes of 50 male guinea pigs weighing 500-600 g were used. The animals were randomly assigned to group 1 (control), group 2 (I/R), group 3 (melatonin + I/R), group 4 (vitamin E + I/R) and group 5 (octreotide + I/R). Groups 3, 4 and 5 received four subcutaneous injections with a 6-h interval for a total daily dose of 10 mg/kg melatonin, 150 mg/kg vitamin E and 22 microg/kg octreotide. The first dose of each substance was administered 5 minutes before retinal ischemia, which was induced for 1.5 hours, followed by reperfusion for 24 hours. All three substances were repeated for 6, 12 and 18 hours during reperfusion. The animals were killed at 24 hours of reperfusion. Retinas were isolated and processed for the quantification of malondialdehyde (MDA).


RESULTS
The compounds had the following relationships: melatonin more than vitamin E more than octreotide in preventing retinal damage by ischemia-reperfusion. All three gave significantprotection against the formation of MDA (10.4+/-2.3, 12.4+/-2.4, 13.9+/-1.5 nmol/100 mg tissue wet weight, respectively) compared to the control (3.7+/-1.3 nmol/100 mg tissue wet weight) and I/R groups (22.7+/-6.2 nmol/100 mg tissue wet weight).


CONCLUSIONS
This study demonstrates the inhibitory effect of melatonin, vitamin E and octreotide on MDA levels during retinal ischemia-reperfusion injury.
Celebi
S
S
Department of Ophthalmology, School of Medicine, Firat University, Elazig, Turkey. scelebi_63@yahoo.com
Dilsiz
N
N
Yilmaz
T
T
Kükner
A Sahap
AS
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D006168:Guinea Pigs; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D015282:Octreotide / Q000494:pharmacology*; D015427:Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D012160:Retina / Q000187:drug effects* / Q000378:metabolism; D012164:Retinal Diseases / Q000378:metabolism / Q000517:prevention & control; D014810:Vitamin E / Q000494:pharmacology*
D000975:Antioxidants; D014810:Vitamin E; D008315:Malondialdehyde; D008550:Melatonin; D015282:Octreotide