Figure 1. Confocal imaging of mouse spinal cord samples and quantification method.

(A) A representative confocal image of a ventral horn spinal cord motor neuron showing GluR1 (red) and synaptophysin (green) staining. Only images of motor neurons located in the lower half of the ventral horn showing a clear nucleus and with a cell body diameter of 20–45µm were used for quantification. Synaptic localization of GluR1, GluR2, and CB1 was measured by the level of percentage of overlapping area with synaptophysin in the whole image field. The white arrows pointing to yellow puncta indicate the synaptic localization of GluR1.

(B) A “ring” of synaptophysin puncta staining surrounding the neuron soma, marked by the white dotted line, was used to define the plasma membrane. The average intensity of the fluorescent signal inside this demarcation was used to quantify total expression levels. Scale bar, 20µm.