Estradiol induces galanin gene expression in the pituitary of the mouse inan estrogen receptor alpha-dependent manner

Estradiol imprinting plays an important role in the regulation of galanin ( GAL) gene expression in the rat. In the anterior pituitary gland, GAL gene expression is greatly induced by estrogen. The relative involvement that th e two estrogen receptor subtypes, alpha and beta, have in regulating this i nduction is not known. We have utilized ER-alpha-knock-out (ER-alpha-KO) mi ce to discriminate the roles of ER alpha and ER beta in the regulation of G AL gene expression in the anterior pituitary gland. Our goals were to measu re the effects of estradiol on GAL gene expression by solution hybridizatio n ribonuclease protection assay in wild-type mice and to determine the role s of ER-alpha and, indirectly, ER-beta by measuring the same response in th e ER-alpha-KO mice. Estradiol treatment for one week elevated GAL gene expr ession 30-40 fold in the wild-type mouse pituitary. Evaluation of estrogen effects on GAL gene expression in the anterior pituitary of ER-alpha-KO ani mals revealed that ER-alpha is essential, because no response to estrogen w as observed in these animals. Since ER-beta mRNA was identified in the ante rior pituitary by RT-PCR, but estrogen had no effects on GAL gene expressio n in the ER-alpha-KO mice, the beta subtype of ER does not appear to partic ipate in estrogen-evoked GAL gene expression in the mouse anterior pituitar y.