How the Gonadal Axis Works

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What is the gonadal axis?

The gonadal axisย involvesย a complex interaction between theย hypothalamus, pituitary gland and theย gonads. This axis helps to regulate development, reproduction,ย 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 theย gland.

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

4. LHย andย 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) andย 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 testosteroneย andย inhibin have a negative feedback effect on the pituitaryย andย hypothalamus.

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

9. As a result, the production of testosteroneย andย 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 theย gland.

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

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

5. When LHย andย FSH bind to the ovaries they stimulate the production of oestrogenย andย 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 oestrogenย andย inhibin have a negative feedback effect on the pituitaryย andย hypothalamus.

7. This leads to the decreased production of GnRH, LHย andย FSH.

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

Gonadal axis females
Female gonadal axis

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