Sequential functional testing of radiation-induced renal damage in the mouse

Area of Science:

• Radiation oncology
• Nephrology
• Animal models

Background:

• Kidney damage from radiation therapy is a significant clinical concern.
• Accurate, noninvasive methods are needed to assess radiation-induced renal impairment in preclinical studies.
• Understanding the dose-response relationship and recovery patterns is crucial for mitigating long-term effects.

Purpose of the Study:

• To develop and validate two nondestructive assays for measuring functional impairment in mouse kidneys following irradiation.
• To establish dose-response relationships and characterize the time course of renal damage and recovery.

Main Methods:

• Developed two noninvasive assays: measurement of daily urine output via urination frequency and assessment of glomerular filtration rate using 51Cr-EDTA excretion.
• Administered local irradiation to both kidneys of mice using 240-kV X rays.
• Monitored functional parameters sequentially over time post-irradiation.

Main Results:

• Urination frequency assay showed a dose-related increase in urine output starting at 17 weeks, with a threshold of 12 Gy by 22 weeks.
• Glomerular filtration rate measured by 51Cr-EDTA excretion provided precise dose-response data, with the blood sample method being more accurate.
• A dose-related latent period of approximately 17 weeks was observed, with partial recovery of kidney function noted between 25 and 38 weeks.

Conclusions:

• The developed urination frequency and 51Cr-EDTA excretion assays are effective, noninvasive tools for assessing radiation-induced renal damage in mice.
• These assays allow for sequential testing and have established a clear dose-related latent period and recovery pattern for kidney function after irradiation.
• The findings provide a foundation for further research into mitigating radiation nephropathy and optimizing radiotherapy protocols.