Figure 4.
Effect of overexpression of ApC/EBP on long-term facilitation in the sensory-motor synapse. (A) Bar graph representing the effect of overexpression of ApC/EBP on long-term facilitation. Overexpression of ApC/EBP by injection of pNEXδ-ApC/EBPL into the sensory cell produced long-term facilitation when it was combined with the application of 10 μM 5-HT for 5 min (one pulse, 1 ×) that can induce only short-term facilitation. The height of each bar corresponds to the mean percentage of change ± SEM in EPSP amplitude tested 24 h after 5-HT (10 μM) treatment. Numbers in parentheses represent the number of the sensory-to-motor synaptic connections tested. Plus (+) symbol in GFP and C/EBP rows indicates the successful expression of the microinjected DNAs (pNEXδ-GFPS65TΔC9 and pNEXδ-ApC/EBPL) in the sensory cells as verified by GFP fluorescence, whereas minus (−) symbol indicates the failure of expression following the microinjection. In some experiments, the DNA construct(s) were not injected, indicated by the zero (0) symbol in the figure. 5-HT row indicates the number of 5-HT pulses treated in the cultures. A one-way analysis of variance and Duncan's multiple range test were used to determine the significance of the EPSP changes (F = 4.57, df = 5, P <0.002). (B) Examples of EPSPs recorded in motor neuron LFS after the stimulation of sensory neurons before (0 h) and 24 h after 5-HT treatment. The recording traces shown in the order of top to bottom in B are the representatives of the corresponding bars shown from left to right in A.