HPG axis, involving the hypothalamus, pituitary, and gonads, is key regulator of sexual development and reproduction through the gonadotropin-releasing hormone (GnRH). The hypothalamus releases GnRH into the median eminence, and GnRH is carried via the hypophyseal portal system to the anterior pituitary. GnRH binds to its receptor, which stimulates production and secretion of gonadotropins into the blood, including luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones bind to receptors in the gonads, stimulating the release of androgen and estrogen steroid hormones. Normally, these sex steroids then negatively feedback inhibit the axis by inhibiting the release of GnRH from the hypothalamus to maintain homeostasis