Receptor for gonadotropin releasing hormone (GnRH) that mediates the action of GnRH to stimulate the secretion of the gonadotropic hormones luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This receptor mediates its action by association with G-proteins that activate a phosphatidylinositol-calcium second messenger system. Ligand interaction triggers steroidogenesis in spermatozoa and follicles. Appears to be involved in contraction of the radula retractor muscle. Widely expressed in peripheral nervous tissue, gonadal tissue and brain. In the brain, expression is high in the palliovisceral lobe and superior buccal lobe but low in the subvertical lobe, superior and inferior frontal lobe, posterior brachial lobe and pedal lobe. Expressed in stomach, rectum, aorta, heart, salivary gland, branchia, pancreas, radula retractor muscle, branchial vessel but not in white body, esophagus, liver and kidney. Belongs to the G-protein coupled receptor 1 family.