The action characteristic of gonadotropin hormone-releasing hormone (GnRH), any of a family of decapeptide amide hormones that are released by the hypothalamus in response to neural and/or chemical stimuli. In at least mammals, upon receptor binding, GnRH causes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) by the anterior pituitary. [ http://www.ncbi.nlm.nih.gov/pubmed/11026571 http://en.wikipedia.org/wiki/Gonadotropin-releasing_hormone https://www.worldcat.org/search?q=bn%3A0198506732 ]