1.3.1. Feedback mechanism

Unit 1 - Fish seed resources and natural breeding of finfishes

1.3.1 Feedback mechanism
  • The level of gonadotropins (GtH) is regulated by a process called feedback mechanism.
  • It is believed that the release of GtH is adjusted through a system of negative feedback, in which centers in the pituitary/hypothalamus are responsive to the level of circulating gonadal steroids.
  • A rise in the level of sex steroids brings about a decrease in GtH secretion; with the result the steroid release again falls to the appropriate level.
  • A drop in the steroid level has the opposite effect (a decrease in the steroid level brings about an increase in the level of GtH).
  • In special cases, an antiestrogen or antiandrogen competes with endogenous gonadal steroids for binding sites in the P-H (pituitary-hypothalamus) axis so that GtH is released regardless of the level of steroids.
  • A negative feedback system becomes then a positive one and results in an artificially elevated level of gonadal steroids. So both the GtH and gonadal steroids continue to rise and the pathway becomes positive.

Last modified: Wednesday, 8 June 2011, 10:29 AM