The preovulatory LH surge A case of a neuroendocrine switch.
The preovulatory surge in LH is a unique endocrine event that involves a switch from the negative feedback effect of estrogen to a positive feedback effect. This occurs at both the level of the brain and that of the pituitary gland. Within the brain the mechanism appears to involve disinhibition of negative inputs to GnRH neurons, as well as stimulation of positive inputs. The positive feedback effects on the brain and the pituitary appear to be coordinated so that the effect of estrogen involves a number of time-delayed mechanisms.
Clarke
I J
IJ
Prince Henry's Institute of Medical Research, Clayton, Victoria 3168, Australia.