Estrogen receptor alpha and beta are both involved in the cerebral VEGF/Akt/NO pathway and cerebral angiogenesis in female mice

Abstract

We have previously demonstrated that vascular endothelial growth factor (VEGF) is critical for cerebral angiogenesis in middle-aged female rats and may play a role in the fow-preserving neuron protective actions of estrogen through its antigenic and ant apoptotic properties. Here, we attempt to elucidate the effects of estrogen and the specifc estrogen receptor (ER) subtype in cerebral VEGF/Akt/NO pathways and cerebral angiogenesis using 15-week old female mice that are either wild-type (WT), lack estrogen receptor α (ERαKO) or β (ERβKO). Protein levels of VEGF and basic signaling molecules of VEGF angiogenic pathway in the frontal cortex were expressed as follows, as revealed by ELISA and immune blotting: a) VEGF; WT: ERαKO: ERβKO, 47 ±15: 27 ±5: 28 ± 5 pg/mg, respectively (P<0.01); b) KDR decreased about 40% in both ERαKO and ERβKO compared to WT; c) Akt was significantly down regulated in both ERαKO and ERβKO compared to WT; d) phosphorylated Akt (pAkt); WT: ERαKO: ERβKO, 0.6 ± 0.2: 0.3 ±0.01: 0.3 ±0.1 units/mg, respectively; e) phosphorylated ENOS significantly decreased about 45% in both ERαKO and ERβKO compared to WT. Cerebral capillary density decreased in both ERαKO and ERβKO compared to WT. Thus, it can be concluded that in female mice VEGF/Akt/ eNOS pathway plays an important role in cerebral angiogenesis and that both ER subtypes are involved in the regulation of VEGF and its signaling molecule expression in the frontal cortex.