Histaurelin acetate is a gonadotropin-releasing hormone (GnRH agonist), which is continuously administered at therapeutic doses and acts as a potent inhibitor of gonadotropin secretion. Subcutaneous histamine acetate can make it insensitive to the effects of gonadotropins, thereby reducing testosterone production. Administration of histamine acetate initially causes an increase in circulating luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels, resulting in a transient increase in sex hormones (testosterone and dihydrotestosterone in males). However, continued administration of histaurelin acetate leads to reversible downregulation of GnRH receptors in the pituitary gland and desensitization of pituitary sex hormones, resulting in a decrease in LH and FSH levels.