Modulatory effects of biogenic amines on adipokinetic hormone secretion from locust corpora cardiaca in vitro.

The control of the release of adipokinetic hormones from neurosecretory cells within the glandular lobes of the corpus cardiacum involving axons running through the paired nervus corporis cardiaci II is unclear. Cyclic-AMP (cAMP) is clearly a second messenger. The effects of four biogenic amines (octopamine, dopamine, tyramine, and serotonin) on the release of adipokinetic hormone-I were investigated in vitro. None had an effect on its own; they all potentiated the hormone release induced by cAMP-activating agents. Dopamine and serotonin were only present in the neurohemal part of the corpus cardiacum. Octopamine and tyramine were not detectable in the corpus cardiacum.