PROFILE OF THE RESPONSIVENESS OF CORPORA ALLATA FROM VIRGIN FEMALE PERIPLANETA-AMERICANA TO AN ALLATOSTATIN FROM DIPLOPTERA-PUNCTATA

Radiochemical measurements of juvenile hormone III biosynthesis by isolated corpora allata from virgin adult female Periplaneta americana have been used to investigate the in vitro sensitivity and pharmacodynamic response of these endocrine glands to a synthetic preparation of an allatostatin from a distantly related cockroach species. The action of this peptide [allatostatin-1 = APSGAQRLYGFGL-amide] from Diploptera punctata towards suitably responsive corpora allata from P. americana was found to be rapid, reversible and dose-dependent. The neurohormone exerted its full effect within approx. 20 min from the start of an in vitro incubation and could be washed out in less than 1 h. The dose-dependency covered the limited range 10(-9)-10(-6) M with an ED50 of approx. 6.9 x 10(-8) M. A study of the inhibitory responses of corpora allata from virgin female P. americana of different ages revealed a clearly-defined developmental pattern of allatostatin sensitivity. It is suggested that the procedures for isolating similar such compounds from P. americana will have been simplified by this clear demonstration of both sensitive and insensitive periods of corpora allata responsiveness to what may be a closely related allatostatic peptide.