[Effects of n-hexane on learning and memory and the expressions of nerve growth factor mRNA and nerve growth factor receptor mRNA of brain tissue in mice exposed to N-hexane].

Objective: To Effects of n-hexane on learning and memory and the expressions of nerve growth factor (NGF) mRNA and nerve growth factor receptor (NGFR) mRNA of brain tissue in mice exposed to N-hexane. Methods: 40 Kunming mice were randomly divided into low-dose group, meddle-dose group, high-dose dose group and control group, with 10 mice in each group. All the groups were orally exposed to n-hexane in different doses: low-dose group with 43.5 mg/kg, middle-dose group with 86.5 mg/kg and high-dose group with 173.0 mg/kg, 1 time per day for 20 d. After the poisoning, the Y-arm test and the expressions of NGF mRNA and NGFR mRNA and the concentrations of NGF and NGFR in the brain tissues of each group were measured. Results: In the first Y-arm test, there existed a significant difference in correct reaction rate generally in all groups (P<0.05), and correct reaction rate in the middle-dose group and the high-dose group were low significantly compared with that in the control group(P<0.05). In the second Y-arm test, there existed a significant differences in total electric shock time and correct reaction rate generally in all groups (P<0.01), and the total electric shock time prolonged significantly and the correct response rate decreased significantly in 3 dose groups compared with those of the control group(P<0.05). The expression levels of NGF mRNA in brain tissues of low, meddle and high dose-groups were 0.81±0.66, 0.67±0.37 and 0.69±0.26, and the expression levels of NGFR mRNA were 1.22±0.42, 1.98±0.84 and 2.01±2.01, respectively. Compared with the control group, the expressions of NGF mRNA in the 3 dose groups decreased significantly (P<0.05), and the expression of NGFR mRNA in middle-and high-dose groups increased significantly (P<0.05). The concentrations of NGF in brain tissues of low,meddle and high dose-groups were 39.97±7.24 ng/L, 39.26±7.88 ng/L,31.70±8.21 ng/L,and the concentrations of NGFR were 17.37±6.82 ng/L,21.37±7.16 ng/L, 22.46±7.70 ng/L, respectively. Compared with the control group, the concentrations of NGF in high-dose groups decreased significantly(P<0.05), and the concentrations of NGFR in middle-and high-dose groups increased significantly (P<0.05). Conclusion: N-hexane exposure can result in decrease of learning and memory in mice, which may be related to abnormal expression of NGF mRNA and NGFR mRNA in brain tissue.