ER-α36, a novel variant of ER-α, is expressed in breast, uterus, digestive tract, respiratory tract etc. The aim of the present study was to investigate the distribution and expression of ER-α36 in the central nervous system (CNS). Here, we comparatively analyzed the expression pattern of ER-α36 in the hippocampus and cortex of neonatal (1-day-old) and adult (12-week-old) Sprague-Dawley (SD) rats by using immunohistochemistry/immunocytochemistry analysis and Western blot. The results showed that ER-α36 was expressed both in hippocampus and cortex of adult rats, but mainly distributed in pyramidal neurons. ER-α36 was mainly located on the cytomembrane of hippocampal and cortical neurons from neonatal rats. Compared with the cortical neurons, the hippocampal neurons showed lower ER-α36 protein expression in the neonatal rats, but exhibited higher level of ER-α36 in the adult rats. Furthermore, the adult rats showed higher levels of ER-α36 expression in both hippocampus and cortex compared with the neonatal rats. These results suggest that ER-α36 might be involved in the regulation of membrane-initiated estrogen signaling throughout the postnatal development of diverse brain regions, and thus will be a potential target for the treatment of degenerative diseases in nervous system.
Animals ; Cerebral Cortex ; metabolism ; Estrogen Receptor alpha ; metabolism ; Hippocampus ; metabolism ; Pyramidal Cells ; metabolism ; Rats ; Rats, Sprague-Dawley ; Signal Transduction

Caveolin-1 (Cav-1), as an important structural protein of caveolae, has been proven to be correlated with several signal transduction pathways. Recent studies have shown that Cav-1 may play a critical role in response to DNA damage in irradiated pancreatic cancer cells. However, it is not known whether down-regulation of Cav-1 is required to enhance the damage of other kinds of human cells exposed to X-radiation. In this study, the role of Cav-1 in Chang liver cell line (CHL) exposed to X-radiation was investigated. Cav-1 knockdown cell line (CHL-CAV7) was stably established by the siRNA plasmids transfection, and Cav-1 expression was suppressed by 60%, compared with that of control group (CHL-C) which was transfected with non-targeting plasmids. Cellular survival ability and the expressions of proteins related to DNA damage and repair were examined by colony formation assay and Western blot, respectively. Down-regulation of Cav-1 expression induced a significant decrease of the survival rate in CHL-CAV7 cells exposed to 8 and 10 Gy X-radiation. Compared with CHL-C cells, CHL-CAV7 cells showed increased γH2AX expression, as well as decreased p-ATM, DNA-dependent protein kinase, catalytic subunit (DNA-PKcs) and p53 protein expressions when treated with X-radiation. Meanwhile, the colocalization of Mdm2 and Cav-1 was decreased in CHL-CAV7 cells compared with that in CHL-C cells. These results suggest that the down-regulation of Cav-1 may aggravate DNA damage of CHL cells through reducing the interaction of Cav-1 and Mdm2, which results in the promotion of p53 degradation.