Figure 2. AAV9-STAS Acts in Proprioceptive Neurons to Improve Sensory-Motor Neurotransmission in SMA Mice.

(A) Representative traces of extracellular recordings from L1 ventral root (VR) after L1 dorsal root (DR) supramaximal stimulation from SMA mice injected with AAV9-GFP, AAV9-STAS, or AAV9-SMN as well as uninjected WT mice at P11. Arrows indicate the maximum amplitude of the monosynaptic reflex. Arrowheads indicate the stimulus artifact. Scale bars: 0.5 mV and 10 ms.

(B) Quantification of spinal reflex amplitudes recorded from the same groups as in (A) at P11. Data represent means and SEM (n ≥ 4). Statistics were performed with one-way ANOVA with Tukey’s post hoc test. ***p < 0.001.

(C) CMAP recordings from the QL muscle after L1 ventral root stimulation in the same groups as in (A) at P11. Arrows indicate maximum amplitude. Arrowheads indicate the stimulus artifact. Scale bars: 0.5 mV and 5 ms.

(D) Quantification of M response amplitudes recorded from the QL muscle in the same groups as in (A) at P11. Data represent means and SEM (n ≥ 3). Statistics were performed with one-way ANOVA with Tukey’s post hoc test. **p < 0.01, ***p < 0.001; ns, not significant.

(E) Representative traces of the first (black) and fifth (red) ventral root (VR) responses recorded after stimulation of the homonymous L1 dorsal root (DR) at 10 Hz from WT and SMA mice as well as SMA mice with selective SMN restoration in either proprioceptive neurons (PV^CRE) or motor neurons (ChAT^CRE) at P11. Arrows indicate the maximum amplitude of the monosynaptic reflex. Arrowheads indicate the stimulus artifact. Scale bars: 0.2 mV and 5 ms.

(F) Quantification of amplitude changes in the monosynaptic reflex after 10-Hz stimulation from the same groups as in (E). Data represent means and SEM (n ≥ 5). Statistics were performed with two-way ANOVA with Tukey’s post hoc test, and significance relative to WT is shown. *p < 0.05, **p < 0.01, ***p < 0.001.

(G) Representative traces of the first (black) and fifth (red) VR responses recorded at P11 after stimulation of the homonymous L1 DR at 10 Hz from the same groups as in (A). Scale bars: 0.2 mV and 5 ms.

(H) Quantification of amplitude changes in the monosynaptic reflex after 10 Hz stimulation from the same groups as in (A). Data represent means and SEM (n ≥ 3). Statistics were performed with two-way ANOVA with Tukey’s post hoc test, and significance relative to WT is shown. ***p < 0.001.

See also Figure S2.