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Induction of antioxidant enzyme activity by hyperoxia (60 % O2) in the developing chick embryo
J C van Golde1, P J Borm, M C Wolfs
1Department of Neonatology, University Hospital, Maastricht University, Maastricht, The Netherlands. JVG@SKIN.AZM.NL
Insights
Premature birth exposes newborns to high oxygen levels when their antioxidant enzyme (AOE) system is immature. Chick embryos exposed to hyperoxia showed temporary AOE induction, varying by enzyme, organ, and exposure timing.
Area of Science:
- Developmental Biology
- Biochemistry
- Physiology
Background:
- Newborns, both human and animal, face high oxygen levels post-birth, contrasting with intrauterine conditions.
- This occurs when their antioxidant enzyme (AOE) system is underdeveloped, potentially leading to oxidative stress.
Purpose of the Study:
- To investigate the impact of hyperoxia on the AOE system in developing chick embryos.
- To determine how AOE activity changes in response to hyperoxia at different developmental stages and in various organs.
Main Methods:
- Chick embryos were exposed to 60% oxygen for 48 hours at different incubation days (10, 14, 18).
- Activities of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) were measured in brain, heart, liver, intestine, and lungs.
Main Results:
- Hyperoxia exposure increased SOD activity 2- to 10-fold in all organs except the brain.
- Catalase and GPx activities were induced only in embryos exposed on day 10, 48 hours post-initiation.
Conclusions:
- Hyperoxia can temporarily induce AOE activity in developing chick embryos.
- This induction is dependent on the specific AOE, the organ, the stage of incubation, and the timing of oxygen exposure.
Abstract:
1. At premature birth, man and animals are exposed to relatively high oxygen levels, compared with intra-uterine conditions, at a time when their antioxidant enzyme (AOE) system is still immature. Using the chick embryo as a study model, we investigated changes in the AOE system in response to hyperoxia applied at different time points during the incubation period. Relations between hyperoxia and AOE activity were studied in selected organs (brain, heart, liver, intestine and lungs) of developing chick embryos (during the second half of the incubation period). 2. Incubated White Leghorn eggs were divided into four groups: control (n = 100) and three test groups exposed for 48 h to 60 % O2 on day 10 (test group 1, n = 80), day 14 (test group 2, n = 60) and day 18 (test group 3, n = 30). Superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) enzyme activities were measured in homogenates of the brain, heart, liver, intestine and lungs. 3. Exposure to hyperoxia at different time points during incubation resulted in a 2- to 10-fold increase in SOD activity in all organs except the brain. Catalase and GPx enzyme activities were only induced in test group 1, 48 h after initiation of hyperoxia. 4. In the developing chick embryo, hyperoxia can produce a temporary induction of AOE activity, which is dependent on the AOE, organ, incubation time and time point of exposure.