Multifactorial control of the release of hormones from the locust retrocerebral complex

The retrocerebral complex of locusts consists of the corpus cardiacum, the corpora allata, and the nerves that connect these glands with the central n ervous system. Both corpus cardiacum and corpora allata are neuroendocrine organs and consist of a glandular part, which synthesizes adipokinetic horm ones and juvenile hormone, respectively, and of a neurohemal part. The glan dular adipokinetic cells in the corpus cardiacum appear to be subjected to a multitude of regulatory stimulating, inhibiting, and modulating substance s. Neural influence comes from secretomotor cells in the lateral part of th e protocerebrum. Up to now, only peptidergic factors have been established to be present in the neural fibres that make synaptic contact with the adip okinetic cells. Humoral factors that act on the adipokinetic cells via the hemolymph are of peptidergic and aminergic nature. In addition, high concen trations of trehalose inhibit the release of adipokinetic hormones. Althoug h there is evidence that neurosecretory cells in the protocerebrum are invo lved in the control of JH biosynthesis, the nature of the factors involved remains to be resolved. (C) 1999 Wiley-Liss, Inc.