Botulinum Neurotoxin Application to the Severed Femoral Nerve Modulates Spinal Synaptic Responses to Axotomy and Enhances Motor Recovery in Rats

Figure 2

Images of synaptic terminals and Iba1⁺ cells in the quadriceps motor nucleus. (a-b) A section containing back-labeled cell bodies of femoral motoneurons (a, arrows) is additionally stained for nuclei (a) and VGAT (b). The boundary of the quadriceps motor nucleus is indicated by a dotted line. Scale bar = 100 μm for (a-b). (c–e) VGAT⁺ and VGLUT 2⁺ axonal terminals (c, e) and VGLUT1⁺ varicosities (arrows, d). Scale bar = 10 μm for (c–e). (f) ChAT staining of two motoneuron cell bodies (MN) surrounded by cholinergic terminals (arrows). Counted were terminals around the MN soma with a visible nucleus (pale area in the center of the MN on the right hand side) which were in focus (thick arrows). Terminals out of focus or only partially seen in the focus plane (thin arrows) were not counted. No quantification was undertaken for the second MN profile (on the left hand side) since it had no visible nucleus. The arrowhead points to a ChAT⁺ cross-sectional profile of a dendrite close to the MN cell body. Such “perisomatic” dendritic profiles could be traced for long distances throughout the section thickness in contrast to the limited extent of the perisomatic terminals in the -axis. (g) Iba1⁺ cells (arrows) some of which surround a motoneuron cell body (MN). Scale bar indicates 25 μm and 50 μm for panels (f) and (g), respectively. (a–g) Shown are representative images from tissue sections after different treatments to illustrate the quality of each staining which was similar in all experimental groups and time points.

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