Fluoro-Gold (FG) retrogradely labeled neurons in specific brain stem nuclei.

<p>The coronal brain sections demonstrated that no FG-positive cells were detected in the brainstems in the control group (Fig A-E, magnifications in A’-E’, P). In the high-dose ChABC-treated groups, FG-positive neurons were detected in the descending/motor related pathway in the medial longitudinal fasciculus (50 U: F, magnifications in F’; 100 U: K, magnifications in K’) and rubrospinal tract (olivary body, 50 U: H, magnifications in H’, H”; 100 U: M, magnifications in M’, M”), and in the ascending/sensory related pathway in the parvicellular reticular nucleus (50 U: G, G’, G”; 100 U: L, magnifications in L’, L”), reticular formation (50 U: I, magnifications in I’, I”; 100 U: N, magnifications in N’, N”), and cuneate and gracile nuclei (50 U: J, magnifications in J’; 100 U: O, magnifications in O’). Mean number of FG-positive neurons in the target regions of the brainstem (P) (n = 3 per group; *<i>p</i><0.05, **<i>p</i><0.01, ****<i>p</i><0.0001, two-way ANOVA, Tukey’s post hoc test). Linear regression analysis comparing the total number of FG-positive cells in the brainstem of the different treatment groups (Q). These reconnections of the descending and ascending pathways suggest that high-dose ChABC may partially promote functional recovery after spinal cord transection. Scale bars: A-J = 1000 μm; A’-J’ = 100 μm. mlf, medial longitudinal fasciculus; RST, rubrospinal tract; PCRt, parvicellular reticular nucleus; RF, reticular formation; Cu & Gr, cuneate and gracile nuclei, respectively. The boxed areas show the higher magnification images of a neuron with visible punctate FG staining (J’) and an artifact (E’).