Bombyx mori prothoracicostatic peptide inhibits ecdysteroidogenesis in vivo

Bombyx prothoracicostatic peptide ( Bom ‐PTSP) is a brain neuropeptide that has recently been reported to have in vitro inhibitory activity to prothoracicotropic hormone (PTTH)‐stimulated ecdysteroid biosynthesis in the prothoracic gland of the silkworm, Bombyx mori . In the present report, Bom ‐PTSP has been shown to significantly decrease hemolymph ecdysteroid titer in the fifth instar larvae when Bom ‐PTSP was injected into the fifth instar day 8 silkworm larvae, resulting in significant delay in spinning behavior. This is the first evidence that Bom ‐PTSP inhibits in vivo ecdysteroidogenesis in the silkworm. Arch. Insect Biochem. Physiol. 56:155–161, 2004. © 2004 Wiley‐Liss, Inc.