A substance that keeps the testicles and ovaries from making sex hormones by blocking other hormones that are needed to make them. In men, luteinizing hormone-releasing hormone agonists cause the testicles to stop making testosterone. In women, they cause the ovaries to stop making estrogen and progesterone. Some luteinizing hormone-releasing hormone agonists are used to treat prostate cancer. Also called GnRH agonist, gonadotropin-releasing hormone agonist, and LH-RH agonist.