Neuronal BDNF Signaling Is Necessary for the Effects of Treadmill Exercise on Synaptic Stripping of Axotomized Motoneurons

Figure 1

Images containing motoneurons retrogradely labeled with the beta subunit of cholera toxin (CTB) (red) are shown from spinal cord sections from intact wild-type mice to illustrate the ways that measurements of synaptic coverage were made. In panel (a), immunoreactivity to vesicular glutamate transporter 1 (VGLUT1) is marked by cyan. In panel (b), immunoreactivity to glutamic acid decarboxylase (GAD67) is shown in green. Each image is from a single optical section of the cell made through the nucleus. In all of the cells studied, the perimeter of the cell was outlined to create a region of interest (ROI) and a profile plot (shown below each image) of the fluorescence intensity along the ROI, in the appropriate channel of the RGB image, was obtained using Image J. The locations of some, but not all, prominent VGLUT1 or GAD67 immunoreactive terminals in contact with the motoneuron soma are indicated by numbers in the micrographs and the labeled peaks on the associated profile plot. The dotted line across each profile plot represents the threshold used to define the amount of synaptic coverage in this cell. Portions of the profile plot above this line are considered regions of the cell surface that are contacted by structures immunoreactive for these synapse-associated proteins.

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