Hormonal feedback

The body uses a variety of mechanisms to keep hormone levels tightly regulated. A critical mechanism is using feedback loops in which a hormone, such as estrogen, feeds back to control its own production. This can be either a positive or a negative feedback loop.

In a negative feedback loop, a stimulus, such as a hormone or a neurotransmitter, causes the release of a product, such as estrogen. When the product reaches a certain level in the bloodstream, it signals to the hypothalamus and anterior pituitary to stops further release of the stimulating hormone or neurotransmitter and thereby leads to reduced levels of the product. For example, testosterone, progesterone and estrogen impact the hypothalamus and anterior pituitary production of GnRH, FSH and LH, via negative feedback to reduce their own production.

The positive feedback loop is the opposite loop. A product signals to produce more of the stimulating hormone or neurotransmitter which causes a continuous increase of the product.

Some of the hormones that act in these ways are seen highlighted in orange in the figures below.

Female reproductive feedback loops:

Male reproductive feedback loops: