Presence of Locusta diuretic hormone in endocrine cells of the ampullae of locust Malpighian tubules

摘要

This is an investigation of an endocrine celltype in the midgut of the migratory locust Locusta migratoria.This cell type is found in the posterior region of the midgut and is especially common in the ampullae through which Malpighian tubules drain into the gut atthe midgut-hindgut junction. Strong Locusta diuretic hormone-like immunoreactivity in these cells was colocalized with FMRFamide- and substance P-like immunoreactivities.At the ultrastructural level,immunoreactivityfor Locusta diuretic hormone was found in spherical granules (mean diameter of 450 nm), the contents of which showed variable electron density. Fractionation of a methanolic extract of the ampullae by reversed-phase high performance liquid chromatography revealed the presence of two peaks of Locusta diuretic hormone-likeimmunoreactive material, both of which stimulate cyclic AMP production by isolated Malpighian tubules. Themore hydrophobic material is most likely Locusta diuretic hormone, which has the same retention time when chromatographed under identical conditions.