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Ontogeny of antioxidant enzymes in the fetal lamb lung
F J Walther1, A B Wade, D Warburton
1Cell Biology Group, Childrens Hospital Los Angeles, University of Southern California School of Medicine.
Insights
Fetal lamb lungs show a rapid increase in antioxidant enzymes, including superoxide dismutase, catalase, and glutathione peroxidase, during late gestation. This surge parallels the development of the surfactant phospholipid, disaturated phosphatidylcholine (DSPC).
Area of Science:
- Biochemistry
- Developmental Biology
- Pulmonary Medicine
Background:
- Pulmonary antioxidant enzyme ontogeny is documented in species with shorter gestation periods.
- Understanding these developmental processes in mammals with longer gestation is crucial for comparative physiology.
Purpose of the Study:
- To investigate the ontogeny of antioxidant enzymes and surfactant phospholipid disaturated phosphatidylcholine (DSPC) in fetal lamb lungs.
- To correlate the development of the antioxidant system with surfactant maturation during late gestation.
Main Methods:
- Lung tissue was collected from 36 fetal lambs between 121 and 145 days of gestation.
- Assays were performed for DSPC content and the activities of superoxide dismutase, catalase, and glutathione peroxidase.
- Enzyme activities and DSPC content were measured per milligram of DNA.
Main Results:
- Superoxide dismutase activity increased from 25 to 139 IU/mg DNA.
- Catalase activity rose from 164 to 483 IU/mg DNA.
- Glutathione peroxidase activity increased from 301 to 447 IU/mg DNA.
- DSPC content increased from 0.48 to 1.61 mg/mg DNA.
- A sharp rise in antioxidant enzyme activity was observed in parallel with DSPC development during the final 15-20% of gestation.
Conclusions:
- Antioxidant enzyme activity and DSPC content increase significantly during the late stages of fetal lamb lung development.
- These findings suggest a coordinated maturation of pulmonary defense mechanisms and the surfactant system before birth.
Abstract:
Pulmonary antioxidant enzyme ontogeny has been reported in species with a relatively short gestation such as hamsters, rats, rabbits, and guinea pigs. We examined the ontogeny of the antioxidant enzyme system together with the surfactant phospholipid disaturated phosphatidylcholine (DSPC) in fetal lamb lung (term is 148 days). Lung tissue from 36 fetuses with gestational ages ranging from 121 to 145 days were assayed for DSPC content and for the activities of three antioxidant enzymes: superoxide dismutase, catalase, and glutathione peroxidase. Between 121 and 145 days gestation superoxide dismutase activity increased from 25 +/- 4 to 139 +/- 18 IU/mg DNA, catalase activity from 164 +/- 23 to 483 +/- 48 IU/mg DNA, glutathione peroxidase activity from 301 +/- 33 to 447 +/- 53 IU/mg DNA, and DSPC content from 0.48 +/- 0.04 to 1.61 +/- 0.11 mg/mg DNA. During the final 15-20% of gestation in the fetal lamb antioxidant enzyme activity rises sharply in parallel with the development of the surfactant system.