Ultrashort feedback

Ultrashort feedback mechanisms are endocrine control loops where a hormone directly inhibits its own secretion via paracrine or autocrine effects.

Characteristically, regulation is maintained without the intermediate step of an additional hormone.

Examples

Examples are the Brokken-Wiersinga-Prummel loop (auto-inhibition of TSH secretion), ultrashort feedback mechanisms of LH and FSH secretion as well as autoregulation of hypothalamic hormone incretion, e.g. GnRH or Galanin.

Control of CRH from hypothalamus is an atypical form, where the ultrashort loop is a positive feedback mechanism. Therefore, CRH stimulates its own secretion in stress or allostatic load.

Ultrashort feedback loops have also been described in synaptic transmission and in the immune system.

See also

• Short Feedback
• Long Feedback
• Ultralong Feedback