Effects of Alpinia oxyphylla fructus on learning-memory and expression of related signal proteins in hippo campus of brain aging mice

Objective To investigate the effects and mechanisms of Alpinia oxyphylla fructus (AOF) on learning and memory in D-galactose induced brain aging mice. Methods The brain aging model was induced by s. c D-galactose. Learning-memory ability was tested by passive avoidance test and Morris water maze test, and the expression of synapsin ( Syn), mitogen-activated protein kinase (MAPK) and protein kinase ( PKC ) in hippocampus were examined by Western blot. Results ① Passive avoidance test:the latency in brain aging group( ( 119.80 ±101.80)s) significantly decreased,and the number of errors (4.4 ± 1.3 ) significantly increased compared with the control group( latency: (279.30 ± 31.64) s; number of errors: ( 1. 8 ±0.9), P＜0. 01 ) ). The latency in low dose, middle dose and high dose AOF group( ( 170.25 ± 68.31 ) s, (226.31 ± 73.25 ) s, (263.20 ± 70.55 ) s) significantly increased, and the number of errors in middle dose and high dose AOF group ( ( 2.8 ± 1.2 ), ( 2.3 ±0. 9 ) ) significantly decreased compared with brain aging group (P ＜ 0. 05, P ＜ 0. 0 1 ). ② Morris water maze test:the escape latency in brain aging group was significantly longer, and the time spent in the original quadrant that previously contained the platform was significantly shorter compared with the control group (P＜0. 01 ). The escape latency in 3 AOF groups was significantly shorter (P＜ 0. 05 ), and the time spent in the original quadrant that previously contained the platform in middle and high dose AOF groups was significantly longer compared with brain aging group (P＜0. 05, P＜0. 01 ). ③ Western blot test:the expression of Syn,MAPK and PKC in hippocampus of brain aging group was significantly weakened than that of the control group. In contrast, the expression of Syn,MAPK, PKC were significantly enhanced in all AOF groups. Conclusion AOF could significantly improve the ability of learning and memory in brain aging mice. Its effects might be related to the increase of the expression of Syn, MAPK and PKC in hippocampus. Key words: Alpinia oxyphylla fructus; Brain aging; Synapsin; Mitngen-activated protein kinase; Protein kinase