[Effects of Xiaotan Huayu Liqiao Formula on cognitive impairment in mice exposed to chronic intermittent hypoxia].

To investigate the improvement effects of Xiaotan Huayu Liqiao Formula on cognitive impairment in mice exposed to chronic intermittent hypoxia (CIH), and to explore the related mechanisms. Forty-eight male C57 BL/6 mice were randomly divided into four groups as Normoxia, CIH, Formula+CIH and Formula group. Mice were exposed to normoxia in the normoxia and formula group, or intermittent hypoxia in CIH or Formula+CIH group (in the chambers, mice were filled with 100% N to produce FiO of 9% for 1. 5 min. The FiO gradually returned to 21% over the remainder of each cycle. The exposure cycle was repeated every 3 min, 8 h/day for 35 days). Mice were treated with Xiaotan Huayu Liqiao Formula at the dose of 26. 8 g/kg by intragastric administration before CIH exposure. Meanwhile, mice in CIH and normoxia group were given the same volume of normal saline. When the experiment lasts for 26-35 d, Morris water maze was used to detect cognitive dysfunction in mice. At the end of 35 days, Y-maze was performed in each group. After anesthesia, hippocampus was isolated for morphological observation and Western blot ananlysis. Nissl staining and electron microscopy were adopted to assess the neuronal damage in hippocampus, and Western blot was used to detect the levels of PSD-95 and synapsin expression. Compared with normoxia group,the performance of CIH mice was significantly reduced in Morris water maze and Y-maze(＜0. 01,＜0. 01). Both the number of Nissl staining positive cells and the thickness of the postsynaptic density in hippocampus were significantly reduced. And, the levels of PSD-95 expression in hippocampus was also decreased in the CIH group(＜0. 01), however, no significant change of synapsin expression was observed. Compared to CIH group, administration of Xiaotan Huayu Liqiao Formula markedly improved performance of mice in Morris water maze and Y-maze (＜0. 01), increased Nissl staining positive cells and the thickness of the postsynaptic density and PSD-95 expression in hippocampus (＜0. 01). Xiaotan Huayu Liqiao Formula could alleviate the structural and functional impairment of the postsynaptic dense area, and improved CIH-induced cognitive dysfunction.