Rehmannia glutinosa's water extracts enhence memory and spatial learning related with increasing EPO level in anemia rats

Abstract

The mechanism of extract from the root of Rehmannia glutinosa (RG), toward the efficacy to anaemia and memory was studied. Anaemia rats model was prepared by injection of CTX (cyclophosphamide) combined with blood extraction, and then administered orally the water extracts of RG (RGWE) for 10 days at the dose of 3, 6, 10 g/kg, respectively. In control group, water as vehicle was administered orally to the anaemic rats for 10 days. All rats were trained and tested in the Morris water maze to evaluate the memory effects. After the anti-anaemic effect of the RGWE was confirmed by detecting Hb and RBC, plasma EPO levels were examined by ELISA assay, and brain EPO and EPOR expression were observed in anaemic rats by immunocytochemistry and western blotting assays. Compared with vehicle group, the escape latencies were reduced obviously and the times of crossing platform were increased significantly in 6, 10 g/kg RGWE groups. Hb, RBC, serum EPO levels increased obviously in anaemia rats treatment with RGWE. Moreover, EPO and EPOR expression in the brain was also up regulated significantly. The numbers of EPO and EPOR positive cells in the RGWE treated rat brains were far higher than those in the vehicle group, especially in 6, 10 g/kg RGWE groups. These results were also observed in Western blotting analyses. RGWE was benefit for the memory and spatial learning in anaemia rats, which may be related with higher EPO and EPOR expression.