Immunochemical identification and expression of allatostatins in the gut of Diploptera punctata

Abstract

Dip-allatostatins are a family of related neuropeptides in the cockroach Diploptera punctata that were identified originally on the basis of their ability to inhibit juvenile hormone biosynthesis by corpora allata. These peptides were subsequently also found to inhibit myogenic and proctolin-induced contractions of the cockroach hindgut. Dip-allatostatin immunoreactive material is distributed in several sites within the brain, subesophageal and ventral ganglia and in nerves to the antennal pulsatile organ and hindgut muscles. We have demonstrated here that Dip-allatostatin immunoreactivity is also found in the proctodeal innervation and endocrine cells of the midgut. The endocrine cells which are distributed unequally in different regions of the midgut are also sites of Dip-allatostatin mRNA synthesis. The quantity of Dip-allatostatin immunoreactive material within and released from the gut was assessed by ELISA and RIA. The changes in Dip-allatostatin content in midgut and hindgut extracts during the first 8 days of the reproductive cycle, paralleled, to some degree, the changes noted previously in brain. Our data suggest that the midgut may be another source from which Dip-allatostatins are released into the hemolymph and this release may be regulated, in part, by nutritional status.