Abstract: Objective Based on cyclic adenosine monophosphate（cAMP）/brain-derived neurotrophic factor（BDNF）/N-methyl-D-aspartic acid（N-methyl-D-aspartic acid,NMDA） pathway to explore the protective effect of ginkgolide B on neurological damage in rats exposed to arsenic. Methods Totally 40 SD rats were divided into normal control group,arsenic exposure group（15 mg/kg）,low and high dose of ginkgolide B group（200,400 mg/kg）. Rats in the arsenic exposure group,low-dose and high-dose ginkgolide B groups were given sodium arsenite by intragastric administration every day for 8 weeks. Ginkgolide B was gavaged,and the normal control group and the arsenic exposure group were given equal volumes of normal saline gavage. After the experiment,the Morris water maze was used to evaluate the spatial learning and memory ability of the rats,and the neurological severity score was used to evaluate the rats' neuropathy and the degree of functional damage.HE staining and Nissl staining was used for pathological observation in rat hippocampus DG area,CA3 area and CA1 area. Enzyme-linked immunosorbent assay was used for the determination of the neurocytokine acetylcholinesterase（AchE） in rat hippocampus,norepinephrine（NE） and monoamine oxidase（MAO） levels,as well as the level of apoptosis in rat hippocampal neurons,and real-time fluorescent reverse transcription and Western blot were used to determine the levels of cAMP,BDNF and NMDA in the hippocampus. Results Compared with the normal control group,the escape latency,neurobehavioral score,hippocampal AchE level,TUNEL positive cell number,times of passing the original platform position,and stay in the original platform quadrant in the arsenic exposure group and the ginkgolide B dose groups were increased. Time,hippocampal NE,MAO levels,cAMP（4.34±0.33 vs 1.86±0.15,1.58±0.13 vs 0.25±0.04）,BDNF（4.59±0.43 vs 1.03±0.20,1.38±0.15 vs 0.37±0.05）,NMDA（4.87 ±0.43 vs 1.03±0.11,1.68±0.18 vs 0.33±0.06） mRNA protein levels were all decreased,and the differences were statistically significant（all P<0.05）. Compared with the arsenic exposure group,the escape latency,neurobehavioral scores,hippocampal AchE levels,and TUNEL positive cells of rats were all decreased in the ginkgolide B dose group. The times of passing the original platform location,the time spent in the original platform quadrant,NE,MAO levels,cAMP（1.86±0.15 vs 2.46±0.19,3.54±0.23,0.25±0.04 vs 0.78±0.09,1.14±0.13）,BDNF（1.03±0.20 vs 2.34±0.25,3.61±0.29,0.37±0.05 vs 0.81±0.08,1.11±0.12）,NMDA（1.03±0.11 vs 2.22±0.25,3.68±0.38,0.33±0.06 vs 0.76±0.08,1.17±0.11） mRNA and protein levels were all increased;and the differences were statistically significant（all P<0.05）. In the normal control group,the neurons in DG,CA1,and CA3 areas of the hippocampus were arranged neatly and densely,and the cell shape was regular and complete. The cytoplasm contained abundant and dense Nissl bodies,and the expression of astrocytes was strong. Brownish-yellow,thick and long processes,few branches,large proportion of cells. Neurons in DG,CA1,and CA3 areas of the arsenic exposure group were loosely arranged,neurons were absent,irregular in shape,mostly triangular or polygonal,and nucleoli were not obvious,the Nissl bodies in the cytoplasm and the astrocytes were significantly reduced,the cell morphology was damaged,the radial nerve mutation was short,and the expression level was reduced. The neurons in the DG,CA1,and CA3 areas of the hippocampus in the ginkgolide B dose group had normal morphology and arranged Neatly,the expression and cell morphology of astrocytes were similar to those in the normal control group. Conclusion In the arsenic-exposed rat model of nerve injury,ginkgolide B has neuroprotective effects,and can significantly improve the learning,cognition,memory and nerve function of rats. The mechanism is related to the activation of hippocampal cAMP/BDNF/NMDA by ginkgolide B access related.

Key words: Cyclic adenosine monophosphate, Brain-derived neurotrophic factor, N-methyl-D-aspartic acid, Ginkgolide B, Arsenic, Neurological impairment