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. Author manuscript; available in PMC: 2010 Sep 15.
Published in final edited form as: Toxicol Pathol. 2008 Dec;36(7S):7S–23S. doi: 10.1177/0192623308327412

FIGURE 1.

FIGURE 1

Regulation of hypothalamic GnRH system and pituitary gonadotropin synthesis and release. Kisspeptin, the ligand of the GPR54 receptor located on GnRH neurons, is a key regulator of GnRH production. Steroids, leptin, and Ghrelin are believed to modulate GnRH secretion via the kisspeptin/GPR54 system. GnRH I and II molecules are present in primates, and both molecules act via GnRH I receptors in gonadotropes. Synthesis and secretion of LH and FSH are locally modulated by a variety of paracrine factors.