[Presence of substances immunoreactively related to enkephalin in an insect, Locusta migratoria]

Application of specific radioimmunoassays to various extracts of the locust showed that nervous tissues and specially the optic lobes contain enkephaline-like material. However these immunoreactive substances present an apparent higher molecular weight (700--1 000 dalton) than those of the controls, as tested by chromatography on Sephadex G 25.