Cockroach Diuretic Hormones: Characterization of a Calcitonin-Like Peptide in Insects

Insect diuretic hormones are crucial for control of water balance. We isolated from the cockroach Diploptera punctata two diuretic hormones (DH), Dippu-DH31and Dippu-DH46, which increase cAMP production and fluid secretion in Malpighian tubules of several insect species. Dippu-DH31and -DH46contain 31 and 46 amino acids, respectively. Dippu-DH46belongs to the corticotropin-releasing factor (CRF)-like insect DH family, whereas Dippu-DH31has little sequence similarity to the CRF-like DH, but is similar to the calcitonin family. Dippu-DH46and -DH31have synergistic effects in D. punctata but have only additive effects in Locusta migratoria. Dippu-DH31represents a distinct type of insect DH with actions that differ from those of previously identified insect peptides with diuretic activity.