Control of gonadotropin feedback: the possible role of estrogen-induced hypothalamic synaptic plasticity.
The preovulatory gonadotropin surge is a critical event in reproduction. Although many explanations have been given for the inhibition--disinhibition cycle referred to as positive feedback, none are completely satisfactory. Recent evidence indicates that the preovulatory surge of gonadotropin is induced, in part, by the disengagement of inhibitory synaptic connections in the hypothalamic arcuate nucleus. This disinhibition of gonadotropin-releasing hormone secretion results in a massive release by the estrogen-sensitized pituitary gonadotrophs. Investigations are presently under way to determine whether other areas of the hypothalamus are involved in this estrogen-induced synaptic plasticity.
Horvath
T L
TL
Yale University School of Medicine, Department of Obstetrics and Gynecology, New Haven, CT, USA.
Garcia-Segura
L M
LM
Naftolin
F
F
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000033:anatomy & histology / Q000502:physiology*; D004967:Estrogens / Q000502:physiology*; D005246:Feedback; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006062:Gonadotropins / Q000502:physiology*; D006801:Humans; D008597:Menstrual Cycle / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D009435:Synaptic Transmission / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D004967:Estrogens; D006062:Gonadotropins; D007987:Gonadotropin-Releasing Hormone; D005680:gamma-Aminobutyric Acid