Figure 1. Five processes by which peptide can potentially modify LH secretion from gonadotropes, with selected examples of activities that are further discussed in the text. The action of the peptide is represented by the black arrows. A, Peptide is transported from the hypothalamus and directly acts on the gonadotrope, e.g., oxytocin (70 ). B, Interaction of peptide from the hypothalamus with GnRH, e.g., NPY (58 ). C, Peptide elicits release of another substance that acts on the gonadotrope and so produces a paracrine mechanism of action, e.g., PACAP stimulates IL-6 release from folliculo-stellate cells (303 ). D, Peptide is released from a cell within the pituitary, e.g., galanin from lactotropes (221 226 ). E, An autocrine process utilizing peptide synthesized within the gonadotrope, e.g., substance P (233 ).
Source: Endocr Rev 1999 Feb;20(1):46-67
Edited by Aldo Campana,