Tong Luo Jiu Nao ameliorates Aβ(1–40)-induced cognitive impairment on adaptive behavior learning by modulating ERK/CaMKII/CREB signaling in the hippocampus

BACKGROUND: Tong Luo Jiu Nao (TLJN), a modern formula of Chinese medicine extracts on the basis of Traditional Chinese Medicine theory, has been used to treat dementia. The present study aimed to investigate its ameliorating effects on Aβ(1–40)-induced cognitive impairment in rats using a series of novel reward-directed instrumental learning (RDIL) tasks, and to determine its possible mechanism of action. METHODS: Rats were pretreated with TLJN extract (0.9 and 1.8 g/kg, p.o.) for 10 daysbefore surgery, and were trained to gain reward reinforcement by lever pressing at the meantime. Thereafter, rats received a bilateral microinjection of Aβ(1–40) in CA1 regions of the hippocampus. Cognitive performance was evaluated with the goal directed (higher response ratio) and habit (visual signal discrimination and extinction) learning tasks, as well as on the levels of biochemical parameters and molecules. RESULTS: Our findings first demonstrated that TLJN can improve Aβ(1–40)-induced amnesia in RDIL via enhancing the comprehension of action-outcome association and the utilization of cue information to guide behavior. Then, its ameliorating effects should attribute to the modulation of ERK/CaMKII/CREB signaling in the hippocampus. CONCLUSION: TLJN can markedly enhance cognitions of Aβ(1–40) microinjection animal model in adaptive behavioral tasks. It has the potential, possibly as complementary and alternative therapy, to prevent and/or delay the deterioration of cognitive impairment in AD.