Estrogen induces estrogen receptor alpha-dependent cAMP response element-binding protein phosphorylation via mitogen activated protein kinase pathway in basal forebrain cholinergic neurons in vivo.
In addition to classical genomic mechanisms, estrogen also exerts nonclassical effects via a signal transduction system on neurons. To study whether estrogen has a nonclassical effect on basal forebrain cholinergic system, we measured the intensity of cAMP response element-binding protein (CREB) phosphorylation (pCREB) in cholinergic neurons after administration of 17beta-estradiol to ovariectomized (OVX) mice. A significant time-dependent increase in the number of pCREB-positive cholinergic cells was detected after estrogen administration in the medial septum-diagonal band (MS-DB) and the substantia innominata (SI). The increase was first observed 15 min after estrogen administration. The role of classical estrogen receptors (ERs) was evaluated using ER knock-out mice in vivo. The estrogen-induced CREB phosphorylation in cholinergic neurons was present in ERbeta knock-out mice but completely absent in ERalpha knock-out mice in MS-DB and SI. A series of in vitro studies demonstrated that estrogen acted directly on cholinergic neurons. Selective blockade of the mitogen activated protein kinase (MAPK) pathway in vivo completely prevented estrogen-induced CREB phosphorylation in cholinergic neurons in MS-DB and SI. In contrast, blockade of protein kinase A (PKA) was effective only in SI. Finally, studies in intact female mice revealed levels of CREB phosphorylation within cholinergic neurons that were similar to those of estrogen-treated OVX mice. These observations demonstrate an ERalpha-mediated nonclassical effect of estrogen on the cholinergic neurons and that these actions are present under physiological conditions. They also reveal the role of MAPK and PKA-MAPK pathway activation in nonclassical estrogen signaling in the basal forebrain cholinergic neurons in vivo.
Szego
Eva M
EM
Neurobiology Research Group, Hungarian Academy of Sciences, Eötvös Loránd University, H-1117 Budapest, Hungary.
Barabás
Klaudia
K
Balog
Júlia
J
Szilágyi
Nóra
N
Korach
Kenneth S
KS
Juhász
Gábor
G
Abrahám
István M
IM
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000172:deficiency / Q000187:drug effects / Q000502:physiology*; D004967:Estrogens / Q000097:blood; D005260:Female; D007546:Isoquinolines / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009474:Neurons / Q000502:physiology*; D010052:Ovariectomy; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010766:Phosphorylation; D013449:Sulfonamides / Q000494:pharmacology
D017362:Cyclic AMP Response Element-Binding Protein; D047628:Estrogen Receptor alpha; D004967:Estrogens; D007546:Isoquinolines; D010726:Phosphodiesterase Inhibitors; D013449:Sulfonamides; D004958:Estradiol; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide