Insulin-like growth factor attenuates apoptosis and mucosal damage in hypoxia/reoxygenation-induced intestinal injury.
OBJECTIVE
Necrotizing enterocolitis (NEC) is a potentially lethal disease among premature infants. The aim of the present study was to investigate whether hypoxia-reoxygenation (H/R)-induced intestinal injury was due to increased apoptosis of the intestinal mucosa in young mice and whether pre-treatment of the animals with recombinant human insulin-like growth factor-I (IGF-I), a known anti-apoptotic factor, could protect the intestinal cells from H/R-induced apoptosis or intestinal injury.


METHODS
Young mice were divided into three groups: group 1 mice (H/R) were hypoxia-reoxygenation; group 2 mice (H/R + IGF-I) were treated with recombinant human IGF-I by intraperitoneal injection (1 mug/g b.w. once daily) for 7 days, and group 3 mice served as control. Hypoxia was induced by placing young mice in a Plexiglas chamber consisting of 10% oxygen for 60 min. After hypoxia, the young mice were reoxygenated for 10 min with 100% oxygen. Intestinal generation of substances reactive to thiobarbituric acid (TBARS) and active caspase-3 were measured in H/R-induced intestinal injury.


RESULTS
Increased numbers of apoptotic cells (apoptotic index) across the villi in young mice subjected to H/R were observed with the TUNEL reaction whereas few apoptotic cells existed in the control animals. In addition, H/R-induced intestinal damage in the H/R + IGF-I group was greatly attenuated, with necrosis limited partially to the mucosa. Tissue-active caspase-3 levels in the H/R group were found to be significantly higher when compared with that of the H/R + IGF-I group of mice and control. However, TBARS concentrations in the intestine were similar in H/R groups when compared to the intestine of control animals.


CONCLUSIONS
The present study suggests that both necrosis and apoptosis, via mechanisms occurring due to oxygen-derived free radicals and activation of caspase-3, play a role in the pathogenesis of H/R-induced bowel injury. We also show that IGF-I protect intestinal mucosa from necrosis and apoptosis from intestinal H/R injury.
Ozen
Samim
S
Department of Pediatrics, Ege University Medical School, Bornova, TR-35100 Izmir, Turkey.
Akisu
Mete
M
Baka
Meral
M
Yalaz
Mehmet
M
Sozmen
Eser Yildirim
EY
Berdeli
Afig
A
Kultursay
Nilgun
N
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000032:analysis; D004195:Disease Models, Animal; D020345:Enterocolitis, Necrotizing; D006801:Humans; D000860:Hypoxia / Q000150:complications*; D020287:In Situ Nick-End Labeling; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage*; D007410:Intestinal Diseases / Q000209:etiology* / Q000473:pathology; D007413:Intestinal Mucosa / Q000737:chemistry / Q000473:pathology*; D007422:Intestines / Q000737:chemistry / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D009336:Necrosis; D010100:Oxygen / Q000008:administration & dosage*; D011994:Recombinant Proteins / Q000008:administration & dosage; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis
D011994:Recombinant Proteins; D017392:Thiobarbituric Acid Reactive Substances; D007334:Insulin-Like Growth Factor I; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D010100:Oxygen