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Effect of methyl prednisolone on normobaric pulmonary oxygen toxicity in rats
Abstract:
Male albino rats were exposed to 81, 86, 90 or 99% oxygen until death. Rats were also administered methyl prednisolone (MP) 10-60 mg/kg/day intraperitoneally. MP-treated rats survived significantly less than controls: 53.5 +/- 4.7 vs. 65.2 +/- 8.2 h, p less than 0.001 in 99% O2, 74.4 +/- 9.4 vs. 120 +/- 39.8 h, p less than 0.02 in 86% O2 and 113.7 +/- 21.4 vs. 162 +/- 17.9 h, p less than 0.03 in 81% O2. Rats were exposed to 99% O2 for 10, 30 and 50 h and the activity of superoxide dismutase (SOD) and catalase in their lungs was monitored. MP-treated rats showed less increase in pulmonary SOD after 10 h (111 vs. 171%, p less than 0.03) but no effect on SOD activity thereafter. MP had no effect on the response of catalase to O2. No effect of MP on lung morphology could be found under the light microscope.
Insights
Methylprednisolone (MP) administration shortened survival times in rats exposed to hyperoxia. This corticosteroid treatment also altered pulmonary superoxide dismutase (SOD) activity, suggesting a complex role in oxygen toxicity.
Area of Science:
- Toxicology
- Pharmacology
- Pulmonary Medicine
Background:
- Hyperoxia, or exposure to high concentrations of oxygen, can lead to oxygen toxicity.
- Corticosteroids like methylprednisolone (MP) are used for their anti-inflammatory properties, but their effects on oxygen toxicity are not fully understood.
Purpose of the Study:
- To investigate the effect of methylprednisolone (MP) on survival and pulmonary antioxidant enzyme activity in rats exposed to hyperoxia.
Main Methods:
- Male albino rats were exposed to varying concentrations of oxygen (81-99%) until death.
- Rats received daily intraperitoneal injections of methylprednisolone (MP) at doses ranging from 10-60 mg/kg/day.
- Pulmonary superoxide dismutase (SOD) and catalase activity were measured after 10, 30, and 50 hours of exposure to 99% oxygen.
Main Results:
- MP treatment significantly reduced survival time in rats exposed to 81%, 86%, and 99% oxygen compared to controls.
- MP administration resulted in a diminished increase in pulmonary SOD activity after 10 hours of 99% oxygen exposure, but had no subsequent effect.
- MP did not affect pulmonary catalase activity or lung morphology under light microscopy.
Conclusions:
- Methylprednisolone (MP) exacerbates oxygen toxicity in rats, leading to decreased survival.
- MP alters the pulmonary antioxidant response, specifically affecting superoxide dismutase (SOD) activity early in hyperoxic exposure.