May act as a neurotransmitter or neuromodulator. Allatostatins A1, A2 and A3 are expressed in brain, antennal lobes, optical lobes, gnathal ganglia, the retrocerebral complex and thoracic, abdominal and ventral ganglia. Allatostain A4 is expressed in brain (at protein level). Belongs to the allatostatin family.