Protective Effect of Corticosteroids on Radiation Pneumonitis in Mice

• Published in: Radiation research 1988-01, Vol.113 (1), p.112-119
• Main Authors: Gross, Nicholas J., Narine, K. Roy, Wade, Randy
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biological effects of radiation; Corticosteroids; Dose response relationship; Female; Fundamental and applied biological sciences. Psychology; Irradiation; Lung - radiation effects; Lungs; Methylprednisolone - therapeutic use; Mice; Mortality; Pneumonia; Pneumonia - etiology; Pneumonia - prevention & control; Radiation dosage; Radiation pneumonitis; Radiation-Protective Agents - therapeutic use; Radioprotection; Radiotherapy; Space life sciences; Steroids; Tissues, organs and organisms biophysics
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3577184

We explored the protective effect of corticosteroids on the mortality of mice that received thoracic irradiation. Methylprednisolone, 100 mg/kg/week, given from 11 weeks after γ irradiation of the thorax resulted in an increase in the LD50 (11-26 weeks) from 14.3 ± 0.3 (mean ± SE) Gy to 17.6 ± 0.4 Gy, P < 0.001, a protection factor of 1.2. Withdrawal of steroids at various times during the period of radiation pneumonitis resulted in accelerated mortality in the next 2-4 weeks, so that the cumulative mortality "caught up" with that of control animals by 4 weeks after steroid withdrawal. However, after the end of the usual period of pneumonitis withdrawal of steroids did not result in accelerated mortality, suggesting that the time when steroids are protective corresponds to the duration of pneumonitis. A smaller dose of steroids, 25 mg/kg/week, was found to be as protective as the larger dose used in the above experiments. The possibility that corticosteroids reduce mortality, even when given many weeks after radiation, may have important practical and theoretical implications.