Updated: 3/7/2018

Hypothalamic-Pituitary Axis (Male)

Topic
Review Topic
0
0
Videos
1
Overview
hypo pit axis
  • Overview
    • hypothalamic-pituitary axis controls 2 functions of testes
      • spermatogenesis
      • synthesis and secretion of male sex steroid hormones
        • testosterone
  • Hypothalamic-pituitary axis
    • hypothalamus
      • GnRH
        • aka gonadotropin-releasing hormone
        • pulsatile GnRH secretion via preoptic nucleus of hypothalamus
          • GnRH travels in hypothalamic-hypophyseal portal blood system
          • GnRH acts on gonadotrophs in anterior lobe of pituitary
            • GnRH → ↑ FSH and LH (pulsatile)
    • pituitary
      • LH
        • aka luteinizing horome
        • LH → (+) Leydig (interstitial) cells → ↑ testosterone
          • LH acts on Leydig cells
            • increases activity of cholesterol desmolase enzyme
              • increases synthesis and secretion of testosterone via cholesterol
                • testosterone has local (paracrine) and distal (endocrine) effects
                  • locally, testosterone acts on Sertoli cells
                    • reinforces pro-spermatogenesis action of Sertoli cells
      • FSH
        • aka follicle-stimulating hormone
        • FSH → (+) Sertoli (sustentacular ) cells → (+) spermatogenesis
          • FSH acts on Sertoli cells
            • increases synthesis and secretion of androgen-binding protein (ABP)
              • Sertoli cells secrete ABP into luminal space of seminiferous tubule, near developing spermatogonia
              • ABP binds testosterone and maintains high local testosterone levels
            • increases synthesis of growth factors and other products that supports developing spermatogonia and supports spermatogenesis
            • increases synthesis and secretion of inhibin
              • inhibin provides negative feedback of hypothalamic-pituitary axis
  • Negative feedback
    • testosterone (via Leydig cells)
      • testosterone acts on hypothalamus
        • inhibits GnRH secretion
      • testosterone acts on anterior lobe of pituitary
        • inhibits LH and FSH secretion
    • inhibin (via Sertoli cells)
      • inhibin acts on anterior lobe of pituitary
        • inhibits FSH secretion 
 

Please rate topic.

Average 4.3 of 4 Ratings

Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine

The complexity of this topic is appropriate for?
How important is this topic for board examinations?
How important is this topic for clinical practice?
VIDEOS (1)
Topic COMMENTS (4)
Private Note