Nephrotoxicity in mice after repeated imaging using 111In- labeled peptides

We determined the renal radiation dose of a series of111Inlabeled peptides using animal SPECT. Because the animals' health deteriorated, renal toxicity was assessed. Methods: Wild-type and megalin-deficient mice were imaged repeatedly at 3- to 6-wk intervals to quantify renal retention after injection of 40-50 MBq of111In- diethylenetriaminepentaacetic acid-labeled peptides (octreotide, exendin, octreotate, neurotensin, and minigastrin analogs), and the absorbed kidney radiation doses were estimated. Body weight, renal function parameters, and renal histology were determined at 16-20 wk after the first scan and compared with those in naive animals. Results: Because of high renal retention,111In-diethylenetriaminepentaacetic acid-exendin-4 scans resulted in a 70-Gy kidney radiation dose in wild-type mice. Megalin-deficient kidneys received 20-40 Gy. The other peptides resulted in much lower renal doses. Kidney function monitoring indicated renal damage in imaged animals. Conclusion: Micro-SPECT enables longitudinal studies in 1 animal. However, long-term nephrotoxic effects may be induced after high renal radiation doses, even with111In-labeled radiotracers. COPYRIGHT

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