Figure 2. Presymptomatic changes of AMPA and CB1 receptors in ventral horn motor neurons of G93A mice.

(A) Staining for GluR1, GluR2 and CB1 (red) and co-staining for synaptophysin (green) in sections from 6 week old wild type littermate control and G93A mice. Synaptophysin puncta outline motor neuron cell bodies. Punctate GluR1, GluR2 and CB1 staining was observed in neuronal cytoplasm as well as in somatic and dendritic plasma membrane. Receptors were defined as localized to the plasma membrane by co-localization with synaptophysin. Examples of synaptically localized receptors that are apposition or co-localization with synaptophysin puncta are highlighted in the black and white panels to the right of the green and red panels. These black and white panels are derived from insets defined by the boxed area in the green and red panels and white marks areas of receptor and synaptophysin co-localization. Scale bars in green and red panels, 20µm. Width of black and white co-localization inset panels, 19µm.

(B) Levels of synaptic and total receptor expression in motor neurons of G93A mice. Values from G93A mice are represented as percentages of wild type values. Synaptic GluR1 increased significantly at this presymptomatic stage. Synaptic and total GluR2 both decreased significantly. Total CB1 receptor decreased significantly. *P<0.05, **P<0.01. Error bars represent SEM. Sample number (N= 37–57 neurons analyzed from G93A and control mice):