Neuropeptide stimulator of juvenile hormone synthesis. Cardioregulatory neurohormone that increases heart beat rate in the adult but not in the larva. Inhibits active ion transport in the midgut of feeding fourth instar and day 2 fifth instar larva, but not in the midgut of pharate or wandering fifth instar larva. Additional isoforms seem to exist. Expressed extensively in the brain, frontal ganglion and terminal ganglion of the day 2 fifth instar larva (at protein level). Not expressed in the larval brain after day 4 of the fifth instar, or in the brain of the pupa or adult. Expression in the terminal ganglion is localized to cells in the posterior portion of the seventh neuromere of day 2 fifth instar larvae. In the pupa and adult expression is detected in the medial region of neuromere 6, the dorsal medial region of neuromere 7, and the posterior neuromere of the terminal ganglion (at protein level). In the frontal ganglion expression decreases in the wandering larvae and is present at low levels in during pupal ecdysis, but is not detected in the adult. Expressed in the subesophageal ganglion of day 2 fifth instar larva, but not at any time before or after day 2. Not expressed in the abdominal ganglia 1-6 of the day 2 fifth instar larva (at protein level). Expressed in the anterior neuromeres of the pterothoracic ganglion in pupa but not in adult (at protein level). Expressed in the unfused abdominal ganglia of day 10 pupae, and in pharate adult is expressed in median neurosecretory cells M1, M2 and M5, but not in median neurosecretory cells M3 and M4 (at protein level). Not expressed in the differentiated median neurosecretory cells M5 of the larva (at protein level). In the pharate adult brain isoform 3 is the predominant form, with lower levels of isoform 2 and very low levels of isoform 1 detected. In the pharate adult nerve cord isoform 3 is the predominant form, with lower levels of isoform 2 and no isoform 1 detected. In the pharate adult frontal ganglion isoform 3 is expressed, but not isoform 1 and isoform 2. Detected in the day 2 fifth-instar larva, wandering larva, pupa and adult. In the 5th instar larva isoform 1 is induced in the nerve cord by starvation, ingestion of the ecdysteroid agonist RH-5992 or parasitization with C.congregata.