Effects of curcumin on the expression of heat shock protein 70 in the hippocampus and spatial learning ability in APPswe/PS1Δ9 transgenic mice

Abstract

Objective To investigate the effect of curcumin on the expression of heat shock protein 70(HSP70) in the hippocampus and spatial learning ability in APPswe/PS1Δ9 transgenic mice, and provide a new theoretical basis for the treatment of Alzheimer’s disease (AD). Methods Mice were divided into wild-type (WT) group, APP/PS1 transgenic group, curcumin-treated group, quercetin combined with curcumin-treated group. The 5-month-old mice in curcumin-treated group received 150 mg·kg-1·d-1 curcumin by intraperitoneal injection for four consecutive weeks. In addition to curcumin, the mice in quercetin combined with curcumin-treated group also received quercetin 50 mg·kg-1·d-1 intraperitoneally for four consecutive weeks. The expression of HSP70 in the hippocampus of APP/PS1 mice was detected by Western blot. Learning and memory ability of APP/PS1 mice were measured by Morris water maze test. The latency of finding the platforms and the number of crossing the platforms were observed. Results The results of Western blot analyses showed that the expression of HSP70 in the hippocampus of APP/PS1 transgenic mice decreased significantly compared with that of WT mice (OD: APPswe/PS1Δ9: 0.31±0.14; WT: 1.14±0.51; P<0.01). The expression of HSP70 in curcumin-treated group significantly increased compared with that of APP/ PS1 transgenic group (OD: 0.91±0.20 in curcumin-treated group; P<0.05). The results of water maze test showed that compared with WT group, in APP/PS1 group, the latency of finding the platforms was significantly longer (APPswe/PS1Δ9: (82.3±6.8)s; WT: (19.5±4.4)s), and the number of crossing the platforms were significantly decreased (APPswe/PS1Δ9: (2.7±1.1); WT: (5.2±2.1)). In curcumin-treated group, the latency of finding the platform ((47.7±7.6)s) was significantly shorter and the number of crossing platform ((4.5±1.9)s) was more than those in APP/ PS1 group. However, in quercetin combined with curcumin-treated group, the latency of finding the platform was significantly longer ((69.7±9.1)s) and the number of crossing platform (3.2±1.6) was decreased compared with those in curcumin-treated group. Conclusion Curcumin can promote the expression of HSP70 in the hippocampus of APP/PS1 transgenic mice, thus improve spatial learning ability of APP/PS1 transgenic mice. These results provide evidences that curcumin may have potential therapeutic value for the treatment of AD. Key words: Curcumin; Heat shock protein 70; Alzheimer’s disease; Quercetin; APPswe/PS1Δ9 transgenic mice