Relationships between lead-induced learning and memory impairments and gut microbiota disturbance in mice

Abstract

Objective: To explore the effect of lead exposure on the neurobehavior and gut microbiota community structure in mice. Methods: In August 2019, 64 C57BL/6 mice were randomly divided into 4 groups: control group (0 ppm) , low lead exposure group (20 mg/l) , medium lead exposure group (100 mg/l) and high lead exposure group (500 mg/l) . During the experiment, they were free to eat and drink. The drinking water of the lead exposure group was mixed with lead acetate, and sodium acetate was added in the control group. After 10 weeks of exposure, the Morris water maze was used to test the learning and memory ability of each group of mice, and then they were sacrificed for sampling. ICP-MS was used to detect lead content in whole blood and brain tissue. ELISA was used to determine the level of IL-1β in mouse serum. 16S rRNA sequencing was used to detect the structural diversity of the intestinal flora in feces, and then the correlation between the flora and behavior indicators was analyzed. Results: In the Morris water maze experiment, compared with the control group, there was no significant difference in the body weight and swimming speed of the mice in the lead exposure groups. The escape latency of the mice in the 100 mg/l and 500 mg/l dose groups was prolonged, and the number of platform crossings decreased (P<0.05) ; meanwhile, the staying time of the mice in the 500 mg/l Pb-treated group in the target quadrant was lower than that of the control group, and the difference was statistically significant (P<0.05) . Compared with the control group, the blood lead content of the mice in each lead exposure group was significantly increased, and the brain lead content of mice in the 500 mg/l dose group was significantly elevated (P<0.05) . The serum IL-1β levels of mice in each lead exposure group were higher than those of the control group (P<0.05) . At the phylum level, the relative abundance of the Proteobacteria phylum in all of Pb-treated groups was significantly increased (P<0.05) ; at the genus level, Allobaculum, Desulfovibrio, Lachnospiraceae_NK4A136_group, Turicibacter and Ureaplasma were significantly increased (P<0.05) . Among them. The relative abundance of Desuffaoibrio, Turici bacter, and Ureaplasma was negatively correlated with the residence time of mice in the quadrant of the platform (r=-0.32, -0.29, -0.44, P<0.05) . Conclusion: Lead exposure induced learning and memory impairments in mice, which may be related to the disturbance of the gut microbiota.