Environmental cues or the administration of luteinizing hormone-releasing hormone analogue (LHRHa) initiates the production of gonadotropin-releasing hormone (GnRH) in the brain. The influence of GnRH stimulates the pituitary to produce gonadotrophins. It is possible for the central dopaminergic system to block this pathway by reducing a dopamine antagonist such as pimozide. Gonadotrophins stimulate the testes to produce testosterone and the follicles to produce progesterone. Testosterone promotes the production of spermatozoa and reproductive behavior in males, and progesterone promotes the maturation of oocytes and ovulation.