Abstract
Background: Oxidative stress may induce apoptosis and influence cell growth and development. NF-êB is a transcription factor probably playing a key role in these processes. How resuscitation with 100% O2 influences these processes are not known. We have established an in vivo model to study the inflammatory process after hypoxia and reoxygenation using transgenic mice that express luciferase under the control of transcription factor NF-êB, enabling real-time in vivo imaging of NF-êB activity in intact animals.
Objective: To study NF-êB in transgenic hypoxic mice reoxygenated using pure oxygen or room air.
Methods: Hypoxic, 4–7 weeks old transgenic NF-êB reporter mice were compared with a control mouse from the same cage, building couples where the two mice have the same parents, the same age, and are submitted to the same environment. All animal experiments were performed according to national guidelines for animal welfare. Hypoxia was induced by breathing 8, 6, 5, or 4% O2 in N2 for 2 hours. The animals were then randomly resuscitated with 21% or 100% O2 for 30 min. NF-êB activity was quantified by an imaging system delivered by Xenogen Corporation, counting the photons emitted from the animal in a complete dark environment. The value is proportional to the NF-êB activity. Luminescence was measured twice from the dorsal side of the head, first basal measurements two days prior to hypoxia, then three hours after reoxygenation.
Results: Hypoxia with 8% and 6% oxygen did not seem to affect the mice and 5% only slightly. However, in 4% oxygen all the mice were affected, acid base balance was gravely disturbed (n= 13), and the mortality was 20% (N= 62). An increase in luminescence was detected especially in the brain where the increase was significantly higher when 100% oxygen (n= 13) was used for reoxygenation compared with room air (n= 17) where no increase was detected (P= 0.03) See figure.
Conclusion: Two hours of hypoxia with 4% oxygen followed by reoxygenation with pure oxygen induced an increase in NF-êB activity measured in transgenic luciferase mice. No increase was detected in mice resuscitated with 21% O2.
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Dohlen, G., Carlsen, H., Blomhoff, R. et al. 74 NF-êB Activation in Transgenic Reporter Mice is Increased after Resuscitation with Pure Oxygen in Contrast to Room Air. Pediatr Res 56, 476 (2004). https://doi.org/10.1203/00006450-200409000-00097
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DOI: https://doi.org/10.1203/00006450-200409000-00097