– Progonadoliberin-2, also known as Progonadoliberin II and GNRH2, belongs to the gonadotropin-releasing hormone family. GNRH2 is specially expressed in midbrain, at significantly higher levels outside the brain (up to 30-fold). GNRH2 can be cleaved into two chains, gonadoliberin-2 and GnRH-associated peptide 2. gonadoliberin-2 regulates reproduction in females by stimulating the secretion of both luteinizing- and follicle-stimulating hormones. The proproteins produce three transcript variants, but produce the same peptide hormone.