Expression of estrogen receptor -α and -β immunoreactivity in the cultured neonatal suprachiasmatic nucleus: With special attention to GABAergic neurons

This study investigated the expression patterns of estrogen receptor -α (ERα) and -β (ERβ) in cultured cells of the suprachiasmatic nucleus (SCN) in neonatal rats by combined application of cell culture and double-label immunocytochemistry. The results revealed that the immunoreactivity for either ERα or ERβ (with predominance of ERβ) was localized in not only neurons but also astrocytes. The co-expression of both ERα and ERα in the same individual cell was also demonstrated by the double-label immunocytochemistry. The observations also provide a direct evidence for the differential expression of ER subtypes within GABAergic SCN neurons in vitro and suggest that estrogen's effect on the SCN may be mediated at least in part by its ER-containing GABAergic neurons.