The Dose Makes the Poison - Studying Toxicity in MEMRI Applications

Barbara Gruenecker¹, Sebastian Frank Kaltwasser¹, Yorick H. Peterse¹, Philipp G. Saemann¹, Mathias Schmidt¹, Carsten T. Wotjak¹, Michael Czisch¹

Different fractionated manganese injections schemes for MEMRI applications have been applied to study their influence on the animals health and stress response and MRI signal intensity in the brain of the often used mouse strain C57BL/6N. 8 applications of 30 mg/kg MnCl2 injected at an interval of 24 hours (8x30/24) were found to produce least toxic side effects while simultaneously producing highest MRI intensity and contrast compared to 6 injections of 30 mg/kg (6x30/48) and 3 injections of 60 mg/kg applied injected with 48 hours intervals. This method may allow functional MRI in freely behaving animals exposed to prolonged paradigms.