Synaptic transmission elevates adenosine 3', 5'-monophosphate (cyclic AMP) in locust neurosecretory cells.

The release of adipokinetic hormones from the neurosecretory cells within the glandular lobe of the corpus cardiacum (CC) of locusts is under the synaptic control of axons within the nervi corporis cardiaca II (NCC II). This synapse has been shown to be aminergic with the transmitter tentatively identified as octopamine. We show here that stimulation of the presynaptic nerves in NCC II produces an increase in adenosine 3',5'-monophosphate (cyclic AMP) in the glandular lobe. Application of octopamine mimics the effect of nerve stimulation. These and other experiments lead us to believe the increase in cyclic AMP is coupled to the process of synaptic transmission, and that the increase occurs within the intrinsic neurosecretory cells of the glandular lobe.