OBJECTIVETo explore the potential effect of Guizhi plus Gegen Decoction (GGD) in improving learning and memory of lipopolysaccharides (LPS) induced neuroinflammatory mice and its possible mechanisms.

METHODSTotally 63 male ICR mice were randomly divided into 5 groups, i.e., the normal control (n = 13), the model group (n = 13), the low dose GGD group (n = 10), the high dose GGD group (n = 14), and the positive control group (n = 13). Mice were intraperitoneally injected with LPS (0.33 mg/kg) to induce Alzheimer's disease (AD) model. Mice in the high and the low dose GGD groups were administered with 12 g/kg or 6 g/kg by gastrogavage for 4 successive weeks. Mice in the control group were intraperitoneally injected with minocycline (50 mg/kg) for 3 days. By the end of treatment LPS were injected 4 h before behavior test each day, and then behavior test was conducted in mice of each group. Effect of GGD on learning and memory of AD mice was observed by using open field test, novel object recognition task, and Morris water maze.

RESULTSOpen field test showed there was no statistical difference in the movement time and the movement distance among all groups (P > 0.05), suggesting that LPS and GGD had no effect on locomotor activities of mice. In novel object recognition test, AD mice spent significantly shorter time to explore novel object after they were induced by LPS (P < 0.05), while for AD mice in the low and high dose GGD groups, their capacities for exploration and memory were significantly improved (P < 0. 05, P < 0.01). Results of Morris water maze showed that AD mice exhibited increased escape latency (P < 0.05) and spent much less time in swimming across the original platform (both P < 0.05). However, AD mice in the low and high dose GGD groups had obvious shortened latency and increased time percentage for swimming (P < 0.05, P < 0.01).

CONCLUSIONGGD possessed certain improvement in learning and memory disorder of LPS induced AD mice.