Cyclic AMP modulates fast axonal transport in Aplysia bag cell neurons by increasing the probability of single organelle movement.

Stimulation of Aplysia bag cell neurons triggers elevation of cAMP and prolonged secretion of ELH neuropeptide. Using video-enhanced microscopy to track individual organelle movements in bag cell neurons, we find that organelle translocation consists of periods of movement interrupted by stationary episodes. cAMP elevation leads to a 2- to 3-fold enhancement of the average rate of organelle transport in both anterograde and retrograde directions.

Inhibition of peptide release from invertebrate neurons by the protein kinase inhibitor H-7.

The protein kinase inhibitor H-7 has been shown to prevent the potentiation of action potentials that normally accompanies an afterdischarge in the bag cell neurons of Aplysia. We have now shown that H-7 attenuates the release of ELH from these neurons during an afterdischarge without influencing the firing frequency or length of the afterdischarge.