Protective effect of melatonin on antioxidative system in experimental ischemia-reperfusion of rat small intestine.
OBJECTIVE
Effect of exogenously administered melatonin (N-acetyl 5-methoxytryptamine) on antioxidant systems in experimental Ischemia-Reperfusion (I-R) of rat gastrointestinal system (GIS) was examined.


METHODS
A total of 40 rats were divided into 4 groups: Group 1 (Sham), Group 2 (I-R), Group 3 (I-R + 10 mg/kg melatonin) and Group 4 (I-R + 20 mg/kg melatonin). Activity levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were determined in small intestines.


RESULTS
There was a significant (p<0.05) reduction in GSH-Px levels in Group 2 (64.16+/-7.02 U/mg protein) compared to Group 1 (80.15+/-9.32 U/mg protein). We observed a meaningful increase in GSH-Px levels in melatonin applied groups (Group 3: 75.94+/-9.83 U/mg protein, Group 4: 78.55+/-9.11 U/mg protein) compared to Group 2. Correspondingly, SOD activity levels were significantly reduced (p<0.001) in Group 2 (24.14+/-4.35 U/mg protein) compared to controls (52.91+/-6.13 U/mg protein). A stronger effect (p<0.001) of melatonin was observed on SOD levels compared to GSH-Px levels in both doses (Group 3: 38.96+/-6.39 U/mg protein, Group 4: 43.07+/-7.76 U/mg protein). Levels of selenium were reduced significantly in Group 2 (1.11+/-0.31 microg/g tissue) compared to Group 1 (2.01+/-0.19 microg/g tissue). Melatonin application in Group 3 (1.13+/-0.28 microg/g tissue) and Group 4 (1.89+/-0.48 microg/g tissue) caused an increase in selenium levels. There was a strong correlation between increases in selenium and GSH-Px levels in Group 4 (r:0.651 p<0.01).


CONCLUSIONS
Melatonin seems to exert its antioxidant effect in GIS tract by stimulating SOD and GSH-Px. Selenium also seems to have an antioxidant contribution on protecting rat gastrointestinal tract I-R injury.
Ustundag
B
B
Department of Biochemistry, College of Medicine, Firat (Euphrates) University, Elazig, 23119, Turkey. ustundagb@hotmail.com
Kazez
A
A
Demirbag
M
M
Canatan
H
H
Halifeoglu
I
I
Ozercan
I H
IH
D000818:Animals; D000975:Antioxidants / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D003300:Copper / Q000097:blood; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D006651:Histocytochemistry; D007421:Intestine, Small / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D008550:Melatonin / Q000378:metabolism / Q000494:pharmacology* / Q000627:therapeutic use; D051381:Rats; D015427:Reperfusion Injury / Q000188:drug therapy / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology*; D012643:Selenium / Q000032:analysis / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D015032:Zinc / Q000097:blood
D000975:Antioxidants; D003300:Copper; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D012643:Selenium; D015032:Zinc; D008550:Melatonin