Identification of epidermal growth factor-secreting cells in the anterior pituitary of lactating female rats.

Epidermal growth factor (EGF) is synthesized and secreted by mammalian anterior pituitary cells. It stimulates GH and prolactin (PRL) secretion, but the cellular origin of EGF is relatively unexplored. The objective of this study was to characterize the cells that secrete EGF in the anterior pituitary of lactating rats. An EGF reverse haemolytic plaque assay (RHPA) was used to identify EGF-secreting cells and this RHPA was combined with immunofluorescence using antibodies to the six major adenohypophysial hormones (i.e. PRL, GH, LH, FSH, TSH and ACTH). Approximately 20% (20.33 +/- 2.96%) of the cells in the pituitary of lactating rats secrete EGF. The EGF-secreting cell population was composed of the following labelled cells: PRL (27%), GH (20%), LH (18%), FSH (14%), TSH (14%) and ACTH (5%). The present study showed that EGF is released by a subpopulation of anterior pituitary cells composed of all the classic hormone-containing cells.