Figure 1.
The developmental upregulation of GlyR is not affected by a neonatal SCT. Dual or triple labeling of GlyRα1 with GlyT2 and gephyrin on fast blue (FB) retrogradely identified TS motoneurons. The experiments were performed on control rats at P1 (control-P1), P7 (control-P7), and 7 d after neonatal SCT (SCT-P7). Each panel corresponds to a single optical section. In each horizontal series, the antigens detected (and their color of detection) are indicated in the lower part of the left panels. In control-P1 (A1), the density of GlyRα1 reached 29.5 clusters per 100 μm on the cell bodies, 45 on the dendrites (Whiskers Box in D). At this stage, 60% of the clusters of GlyRα1 faced GlyT2-immunoreactive axon terminals on the cell bodies, 75.1% on the dendrites (A2, E), and >75% of the GlyRα1 clusters were colocalized with gephyrin on the cell bodies, 94.8% on the dendrites (A3, F). On motoneurons of control-P7 (B1), the rate of expression of the GlyRα1 significantly increased compared with control-P1 and their density reached 48.9 on the cell bodies, 62.9 on the dendrites (D; Kruskal–Wallis nonparametric test, P1 vs P7, *p < 0.05). At this stage, the association of GlyRα1 with GlyT2 reached 69.4% on the soma, 75.6% on the dendrites (B2, E), while the colocalization of GlyRα1 with gephyrin was almost total on both soma (91.8%) and dendrites (91.7%; B3, F). Seven days after neonatal SCT (SCT-P7), the density of GlyRα1-immunopositive clusters remained remarkably similar (C1) to those quantified on motoneurons of age matched-controls, on both cell bodies and dendrites (D; Control-P7 vs SCT-P7, p = 0.99 for both soma and dendrites). The neonatal SCT did not significantly affect the rate of association of GlyRα1 with GlyT2 on both cell bodies (68.1%) and dendrites (80.3%) compared with P7-control animals (C2, E; Control-P7 vs SCT-P7; p = 0.11 for soma and 0.8 for dendrites). Similarly, on SCT-P7 rats, the rate of colocalization of GlyRα1 with gephyrin (C3) did not significantly change compared with P7 animals on both soma (98.05%) and dendrites (91.04%; F; Control-P7 vs SCT-P7, p = 0.6 for soma and 0.88 for dendrites).