Estrogen receptors and insulin-like growth factor-I receptors mediate estrogen-dependent synaptic plasticity.
Previous studies have shown that estradiol induces a transient disconnection of axo-somatic inhibitory synapses in the hypothalamic arcuate nucleus of adult ovariectomized rats. The synaptic disconnection is accompanied by an increase in the levels of insulin-like growth factor-I (IGF-I) in the arcuate nucleus, suggesting that IGF-I signaling may be involved in the estrogen-induced synaptic plasticity. The role of estrogen receptors and IGF-I receptors in the synaptic changes has been studied by assessing the number of axo-somatic synapses in ovariectomized rats treated with intracerebroventricular administration of the estrogen receptor antagonist ICI 182,780 and the IGF-I receptor antagonist JBI to ovariectomized rats. Estradiol administration resulted in a significant decrease in the number of axo-somatic synapses on arcuate neurons in control ovariectomized rats. Both the estrogen receptor antagonist and the IGF-I receptor antagonist blocked the estrogen-induced synaptic decrease. This finding suggest that estrogen-induced synaptic plasticity in the arcuate nucleus is dependent on the activation of both estrogen receptors and IGF-I receptors.
Cardona-Gómez
G P
GP
Instituto Cajal, CSIC, Madrid, Spain.
Trejo
J L
JL
Fernandez
A M
AM
Garcia-Segura
L M
LM
D000818:Animals; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000502:physiology*; D005260:Female; D000077267:Fulvestrant; D007260:Infusion Pumps; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D009473:Neuronal Plasticity / Q000502:physiology*; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar; D011960:Receptors, Estrogen / Q000502:physiology*; D017451:Receptors, Somatomedin / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D004965:Estrogen Antagonists; D004967:Estrogens; D011960:Receptors, Estrogen; D017451:Receptors, Somatomedin; D000077267:Fulvestrant; D004958:Estradiol; D007334:Insulin-Like Growth Factor I