Example of typical location of α-motoneurons innervating LG muscle in L5 spinal segment.

<p>The spinal grey matter borderline is marked. Retrogradely labeled motoneurons (framed) are shown enlarged below. Motoneurons were labeled with True Blue fluorescence tracer injected into the LG muscle belly.</p

Identification of glutamatergic (VGLUT1; indigo) and cholinergic (VAChT; green) terminals abutting on LG α-motoneuron (α-MN) labeled by means of immunofluorescence (IF).

<p>LG MN perikaryon and proximal parts of dendrites were identified with True Blue (turquoise; A, C, E and G) and all synaptic terminals apposing LG α-MN were identified by synaptophysin IF (red). A-C present single optical section (0.21 μm thick); framed areas on C (merge of A-B) are shown with higher magnification in D to demonstrate contiguity of VAChT or VGLUT1 varicosities with the edge of the α-MN perikaryon. E-H are stacks of 20 optical sections of the same α-MN to show 3D reconstruction of the glutamatergic (indigo) and cholinergic (green) terminals among all synaptic terminals (synaptophysin) abutting on LG α- MN. G–merge of E and F. H—glutamatergic (magenta) and cholinergic (yellow) terminals shown to contact α-MN surface were accepted for quantification while the other (white) terminals, which did not fulfill these criteria, were not analyzed.</p

The direct M₁ responses and H₃-reflexes recorded in the rat soleus muscle during stimulation sessions of low-threshold proprioceptive fibers in the tibial nerve.

<p><b>A.</b> Examples of the raw data averaged after 7200 burst repetitions. Arrows indicate stimulus artifacts. <b>B</b>. The mean areas of the H₃-reflexes (blue line) and M₁-responses (green line) during consecutive days of stimulation in six rats. Four 3 min samples daily were taken for the analysis: at the beginning and at the end of the first and fourth stimulation sessions. The data are expressed as a percentage of M_max values for individual animals.</p

Electrical Stimulation of Low-Threshold Proprioceptive Fibers in the Adult Rat Increases Density of Glutamatergic and Cholinergic Terminals on Ankle Extensor α-Motoneurons - Fig 4

<p><b>Changes in the number (A) and in the aggregate volume (B) of VGLUT1 IF synaptic terminals contacting LG α-MNs after seven days of stimulation of Ia fibers in the tibial nerve.</b> Data are reported as mean +/- SEM. Both the number and aggregate volume of VGLUT1 terminals were increased on the stimulated comparing to sham-stimulated side (*p = 0.03 and *p< 0.05, respectively, <i>Wilcoxon</i> test).</p

The number of TB-identified LG α-MNs subjected to the analysis of VGLUT1- and VAChT IF synaptic terminals apposing their cell bodies.

<p>(N)—the number of animals per group. The numbers of analyzed synaptic terminals are shown in square brackets.</p