Factors affecting allatostatin release in a cockroach ( Diploptera punctata): Nerve section, juvenile hormone analog and ovary

Abstract

The effect of topical application of a juvenile hormone analog, 7S-hydroprene, on juvenile hormone synthesis and the release into the hemolymph of allatostatins (neuropeptides that inhibit juvenile hormone synthesis) was assayed in adult male Diploptera punctata in which nerves to the corpora allata were severed or left intact. Hormone production by corpora allata was measured in vitro radiochemically; allatostatins were quantified by radioimmunoassay. Corpora allata with nerves intact were strongly inhibited by 7S-hydroprene; those with severed nerves (denervated) were less inhibited. Hemolymph allatostatins were highly elevated (>3 nM) above normal (<0.04 nM) only in 7S-hydroprene treated animals with denervated corpora allata. This suggests that allatostatins are normally released at nerve terminals within the corpora allata and that following denervation of the corpora allata allatostatins are released into the hemolymph and inhibit juvenile hormone synthesis less effectively. When ovarioles were implanted into 7S-hydroprene treated males with denervated corpora allata, hemolymph allatostatins were markedly reduced; juvenile hormone synthesis was higher after implantation of vitellogenic ovarioles than when a previtellogenic ovary was implanted. Thus, juvenile hormone analog acts on the brain to release allatostatins and the ovary counteracts this action. These experiments indicate that both juvenile hormone and the ovary affect juvenile hormone synthesis through release of allatostatins.