Figure 2.
Splicing of K/L is influenced by activity. A, Overlaid traces to show examples of typical whole-cell voltage-clamp recordings (Vh = −60 mV) of action-potential-dependent synaptic currents from a WT aCC motoneuron in a wall-climbing third-instar larva. This activity represents the output of the locomotor central pattern generator (Baines, 2003). B, Feeding of GABA (1 mg/ml) to sda larvae is sufficient to dramatically reduce amplitudes of synaptic currents recorded in aCC (average values, 68.9 ± 5.4 vs 28.9 ± 3.5 pA/pF, WT vs GABA, p ≤ 0.01, n ≥ 8). C, Feeding WT larvae PTx is also sufficient to greatly increase their MRT to electroshock (27.9 ± 6.0 vs 154 ± 41 s). This is a measure of susceptibility to seizure (see Materials and Methods). In contrast, feeding GABA (1 mg/ml) to sda larvae is sufficient to rescue MRT (169.5 ± 16.9 vs 64.2 ± 15.5 s). Identical letters denote p ≤ 0.01, n ≥ 20. D, Analysis of splicing of DmNav in whole CNS shows that exposure of WT larvae to PTx is sufficient to saturate inclusion of exon L to 100% (p ≤ 0.01). In contrast, feeding of GABA to sda larvae is sufficient to rescue inclusion of exon K (i.e., a reduction in exon L to 92.6%, p ≤ 0.01).