Silencing allatostatin expression using double-stranded RNA targeted to preproallatostatin mRNA in the German cockroach.

YXFGL-NH(2) family allatostatins (ASTs) were isolated from cockroach brain extracts based on their capacity to inhibit juvenile hormone (JH) biosynthesis in corpora allata (CA) incubated in vitro. Subsequently, the inhibitory activity of synthetic ASTs was demonstrated experimentally, although these peptides were shown to be active as JH inhibitors only in cockroaches, crickets, and termites. Here, we sought to examine whether ASTs are true physiological regulators of JH synthesis. To this end, we used RNA interference methodologies and the cockroach Blattella germanica as a model. Treatments with double-stranded RNA targeting the allatostatin gene in females of B. germanica produced a rapid and long-lasting reduction in mRNA and peptide levels in both brain and midgut during the reproductive cycle. Nevertheless, while brain AST levels were reduced approximately 70-80%, JH synthesis did not increase in any of the age groups tested.