Figure 1.

In sensory neurons from juvenile Aplysia, 5HT-induced activation of PKA and modulation of I_KS appears to be fully mature as indicated by the significant increase in excitability that is identical in magnitude to that observed in mature sensory neurons (A, see text). In addition, as in the adult CNS, 5HT is capable of producing significant increases above basal levels in adenylate cyclase activity in the pleural ganglia as early as stage 11. SCP (2 μm), a neuromodulatory peptide, which is known in adult Aplysia to activate PKA and modulate I_KS, is also capable of producing increases in excitability and increases in adenylate cyclase activity in juvenile neurons.