Gonadotropin-releasing hormone (GnRH) is a hypothalamic decapeptide that, following its release from axon terminals at the median eminence, stimulates the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) from the pituitary gland. GnRH can also reach the central nervous system (CNS), as GnRH neurones in the hypothalamus can have axons that extend into other regions of the CNS including the limbic system (Silverman et al., 1987). In addition, GnRH can cross the blood-brain barrier, from the median eminence, into the third ventricle cerebrospinal fluid, albeit with low efficiency (Caraty and Skinner, 2008). GnRH receptor expression has been demonstrated at sites within the CNS (Jennes et al., 1997, Albertson et al., 2009, Schang et al., 2011) and a range of peripheral tissues (Hapgood et al., 2005, Skinner et al., 2009). Thus, when GnRH analogs are used therapeutically in human and veterinary medicine, it is also important to consider the effects at these non-reproductive sites.