PRESENCE OF LOCUSTA DIURETIC HORMONE IN ENDOCRINE-CELLS OF THE AMPULLAE OF LOCUST MALPIGHIAN TUBULES

This is an investigation of an endocrine cell type in the midgut of th e migratory locust Locusta migratoria. This cell type is found in the posterior region of the midgut and is especially common in the ampulla e through which Malpighian tubules drain into the gut at the midgut-hi ndgut junction. Strong Locusta diuretic hormone-like immunoreactivity in these cells was colocalized with FMRFamide- and substance P-like im munoreactivities. At the ultrastructural level, immunoreactivity for L ocusta diuretic hormone was found in spherical granules (mean diameter of 450 nm); the contents of which showed variable electron density. F ractionation of a methanolic extract of the ampullae by reversed-phase high performance liquid chromatography revealed the presence of two p eaks of Locusta diuretic hormone-like immunoreactive material, both of which stimulate cyclic AMP production by isolated Malpighian tubules. The more hydrophobic material is most likely Locusta diuretic hormone , which has the same retention time when chromatographed under identic al conditions.