How the Gonadal Axis Works

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What is the gonadal axis?

The gonadal axisΒ involvesΒ a complex interaction between theΒ hypothalamus, pituitary gland and theΒ gonads. This axis helps to regulate development, reproduction,Β ageing and many other key physiological processes.

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How the male gonadal axis works

1. The hypothalamus secretes GnRH.

2. GnRH travels down to the anterior pituitary gland and binds to receptors on theΒ gland.

3. This promotes the release of LH (luteinizing hormone) andΒ FSH (follicle-stimulating hormone).

4. LHΒ andΒ FSH travel in the bloodstream to the testicles.

5. LH stimulates Leydig cells in the testicles to produce testosterone (testosterone is required for spermatogenesis and many other important biological processes).

6. FSH stimulates Sertoli cells to produce androgen binding globulin (ABG) andΒ inhibin:

  • Androgen binding globulin is a protein that binds to testosterone and prevents it from leaving the seminiferous tubules
  • Inhibin helps support spermatogenesis and inhibits the production of FSH, LH and GnRH

7. Increased levels of testosteroneΒ andΒ inhibin have a negative feedback effect on the pituitaryΒ andΒ hypothalamus.

8. This results in decreased production of LH and FSH.

9. As a result, the production of testosteroneΒ andΒ inhibin is also decreased.

Gonadal axis
Male gonadal axis

How the female gonadal axis works

1. The hypothalamus secretes GnRH.

2. GnRH travels down to the anterior pituitary gland and binds to receptors on theΒ gland.

3. This promotes the release of LH (luteinizing hormone) andΒ FSH (follicle-stimulating hormone).

4. LH andΒ FSH travel in the bloodstream to the ovaries.

5. When LHΒ andΒ FSH bind to the ovaries they stimulate the production of oestrogenΒ andΒ inhibin:

  • Oestrogen helps to regulate the menstrual cycle and is an essential component in many other physiological processes
  • Inhibin causes inhibition of activin which is usually responsible for stimulating GnRH production

6. Increasing levels of oestrogenΒ andΒ inhibin have a negative feedback effect on the pituitaryΒ andΒ hypothalamus.

7. This leads to the decreased production of GnRH, LHΒ andΒ FSH.

8. This, in turn, results in decreased production of oestrogen and inhibin.

Gonadal axis females
Female gonadal axis

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