NEUROPEPTIDE REGULATORS OF INSECT CORPORA ALLATA

Neuropeptides of the insect brain that regulate juvenile hormone synth esis by the corpora allata include allatotropins, stimulatory modulato rs, and allatostatins, inhibitory modulators. A radiochemical assay fo r juvenile hormone synthesis by corpora allata in vitro was utilized i n the high pressure liquid chromatographic isolation of brain neuropep tides leading to the determination of their primary structure. Identif ied are an allatotropin and an allatostatin from a Lepidopteran, Mandu ca sexta, and a family of five allatostatins from a Dictyopteran, Dipl optera punctata. These neuropeptides are all unique, effective at low concentration (10(-10) to 10(-8) M), act quickly (within hrs) and appe ar to be effective only within the same order of insects as that from which the peptides were isolated. The physiological state of the corpo ra allata conditions the effectiveness of the allatostatins of D. punc tata. These neuropeptide regulators of corpora allatal function may ha ve multiple regulatory roles. This is indicated for D. punctata allato statin I by specific receptors in brain and fat body as well as in cor pora allatal membrane preparations, and also by immunocytochemical loc alization of allatostatin I in medial nerve cells that terminate withi n the brain as well as in the lateral neurosecretory cells that termin ate on corpus allatum cells.