The hypothalamic–pituitary–testicular (HPT) axis represents the central regulatory system controlling male reproductive physiology. It coordinates hormonal signaling between the hypothalamus, anterior pituitary gland, and testes to maintain spermatogenesis and androgen production.
Gonadotropin-releasing hormone (GnRH) is secreted in a pulsatile fashion from the hypothalamus, stimulating the anterior pituitary to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH activates Leydig cells to produce testosterone, while FSH stimulates Sertoli cells to support spermatogenesis.
Testosterone exerts negative feedback on both hypothalamic and pituitary levels, ensuring hormonal balance. Disruption of the HPT axis may result from obesity, chronic illness, pituitary tumors, systemic inflammation, or aging.
Clinical evaluation includes serum testosterone, LH, FSH, prolactin, and sometimes pituitary imaging. Understanding this axis is fundamental for diagnosing hypogonadism and male erotic infertility.
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