Age-dependent changes in MRI of motor brain stem nuclei in a mouse model of ALS.

Mice over-expressing the mutant human G93A-SOD1 are widely used as an animal model of amyotrophic lateral sclerosis (ALS). ALS is characterized by progressive degeneration of motor neurons in the motor cortex, brain stem and spinal cord. The underlying mechanisms for the selective death of motor neurons are still uncertain. To study factors that cause selective neuron degeneration or therapeutic approaches to delay the progression of the disease, a method is required to monitor the state of motor neurons under in-vivo conditions. Here, we demonstrate that in G93A-SOD1 mice the MRI signal intensities of nucleus V, VII, XII, and nucleus ambiguus show a time-dependent increase starting around day 90, parallel to first behavioral signs of a motoneuron disorder.