COCKROACH ALLATOSTATIN-IMMUNOREACTIVE NEURONS AND EFFECTS OF COCKROACH ALLATOSTATIN IN EARWIGS

A monoclonal antibody to allatostatin I of the cockroach Diploptera pu nctata was used to demonstrate the presence of allatostatin-immunoreac tive cells and fiber tracts in the neuroendocrine system of the earwig Euborellia annulipes. The corpora cardiaca cells were not immunoreact ive, nor were the neurosecretory endings of fiber tracts from the brai n to the corpora cardiaca. No immunoreactive material was detected in the corpus allatum, although the corpus allatum contained neurosecreto ry endings, and some cells of the brain, including medial and lateral protocerebral cells, showed immunoreactivity. In addition, the recurre nt and esophageal nerves were allatostatin-positive. The last abdomina l ganglion contained immunoreactive somata, and immunoreactive axons o f the proctodeal nerve innervated the rectum, anterior intestine, and posterior midgut. We did not detect reactive endocrine cells in the mi dgut. Allatostatin I at concentrations of 10(-5) and 10(-7) M did not inhibit juvenile hormone biosynthesis by E. annulipes corpora allata i n vitro. This was true for glands of low activity from 2-day females a nd brooding females, as well as for relatively high activity glands fr om 10-day females. In contrast, 10-7 M allatostatin I significantly an d reversibly decreased hindgut motility. Motility was decreased in hin dguts of high endogenous motility from 2-day females and in those of r elatively low activity from brooding females. These results support th e notion that a primary function of allatostatin might be to reduce gu t motility. Arch. Insect Biochem. Physiol. 38:155-165, 1998. (C) 1998 Wiley-Liss, Inc.