Secretion of gonadotropin-releasing hormone (GnRH) is the final common pathway for the neuroendocrine control of reproduction. The factors regulating GnRH release are poorly understood. Recently, it was discovered that the peptide orphanin FQ (OFQ), also known as nociceptin, is found in a high percentage of GnRH neurons (Foradori et al.,abstract SFN 2003) and that OFQ can reduce GnRH release in vitro (Dhandapani and Brann, 2002). This suggests that OFQ plays a previously undisclosed role in controlling GnRH activity and/or can be secreted from the hypothalamus to affect anterior pituitary function. Thus, to study the direct effects of OFQ on GnRH cells and to explore mechanisms for possible downstream neuroendocrine effects of OFQ we have begun to examine the distribution of the OFQ receptor, opioid receptor like-1 (ORL-1) in brain and pituitary and in a GnRH secreting cell line, GT1-7. GT1-7 cells have proven to be the cell line with characteristics most similar to endogenous GnRH neurons. Therefore, we w...